WIP: Store descriptor in metadata so invite can be deleted.

Change location permission to uses-permission-sdk-23

See merge request briar/briar!1001

.gitlab-ci.yml

@@ -12,7 +12,7 @@ test:
 
   script:
     - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom test
+    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom test --continue
 
   after_script:
     # these file change every time but should not be cached

.idea/runConfigurations/All_in_briar_headless.xml

@@ -3,7 +3,7 @@
     <module name="briar-headless" />
     <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
     <option name="ALTERNATIVE_JRE_PATH" />
-    <option name="PACKAGE_NAME" value="" />
+    <option name="PACKAGE_NAME" value="org.briarproject.briar.headless" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />

bramble-android/build.gradle

@@ -1,3 +1,5 @@
+import com.android.build.gradle.tasks.MergeResources
+
 apply plugin: 'com.android.library'
 apply plugin: 'witness'
 apply from: 'witness.gradle'
@@ -9,8 +11,8 @@ android {
 	defaultConfig {
 		minSdkVersion 14
 		targetSdkVersion 26
-		versionCode 10103
-		versionName "1.1.3"
+		versionCode 10105
+		versionName "1.1.5"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
@@ -29,8 +31,9 @@ configurations {
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
 	tor 'org.briarproject:tor-android:0.3.4.8@zip'
+	tor 'org.briarproject:obfs4proxy-android:0.0.7@zip'
 
-	annotationProcessor 'com.google.dagger:dagger-compiler:2.0.2'
+	annotationProcessor 'com.google.dagger:dagger-compiler:2.19'
 
 	compileOnly 'javax.annotation:jsr250-api:1.0'
 
@@ -39,13 +42,29 @@ dependencies {
 	testImplementation "org.jmock:jmock:2.8.2"
 	testImplementation "org.jmock:jmock-junit4:2.8.2"
 	testImplementation "org.jmock:jmock-legacy:2.8.2"
-	testImplementation "org.hamcrest:hamcrest-library:1.3"
-	testImplementation "org.hamcrest:hamcrest-core:1.3"
 }
 
-project.afterEvaluate {
-	copy {
-		from configurations.tor.collect { zipTree(it) }
-		into 'src/main/res/raw'
+def torBinariesDir = 'src/main/res/raw'
+
+task cleanTorBinaries {
+	doLast {
+		delete fileTree(torBinariesDir) { include '*.zip' }
 	}
 }
+
+clean.dependsOn cleanTorBinaries
+
+task unpackTorBinaries {
+	doLast {
+		copy {
+			from configurations.tor.collect { zipTree(it) }
+			into torBinariesDir
+		}
+	}
+	dependsOn cleanTorBinaries
+}
+
+tasks.withType(MergeResources) {
+	inputs.dir torBinariesDir
+	dependsOn unpackTorBinaries
+}

bramble-android/src/main/java/org/briarproject/bramble/BrambleAndroidEagerSingletons.java

@@ -0,0 +1,11 @@
+package org.briarproject.bramble;
+
+import org.briarproject.bramble.battery.AndroidBatteryModule;
+import org.briarproject.bramble.network.AndroidNetworkModule;
+
+public interface BrambleAndroidEagerSingletons {
+
+	void inject(AndroidBatteryModule.EagerSingletons init);
+
+	void inject(AndroidNetworkModule.EagerSingletons init);
+}

bramble-android/src/main/java/org/briarproject/bramble/BrambleAndroidModule.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble;
 
+import org.briarproject.bramble.battery.AndroidBatteryModule;
 import org.briarproject.bramble.network.AndroidNetworkModule;
 import org.briarproject.bramble.plugin.tor.CircumventionModule;
 import org.briarproject.bramble.system.AndroidSystemModule;
@@ -7,10 +8,15 @@ import org.briarproject.bramble.system.AndroidSystemModule;
 import dagger.Module;
 
 @Module(includes = {
+		AndroidBatteryModule.class,
 		AndroidNetworkModule.class,
 		AndroidSystemModule.class,
 		CircumventionModule.class
 })
 public class BrambleAndroidModule {
 
+	public static void initEagerSingletons(BrambleAndroidEagerSingletons c) {
+		c.inject(new AndroidBatteryModule.EagerSingletons());
+		c.inject(new AndroidNetworkModule.EagerSingletons());
+	}
 }

bramble-android/src/main/java/org/briarproject/bramble/battery/AndroidBatteryManager.java

@@ -0,0 +1,84 @@
+package org.briarproject.bramble.battery;
+
+import android.app.Application;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+
+import org.briarproject.bramble.api.battery.BatteryManager;
+import org.briarproject.bramble.api.battery.event.BatteryEvent;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.lifecycle.Service;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import static android.content.Intent.ACTION_BATTERY_CHANGED;
+import static android.content.Intent.ACTION_POWER_CONNECTED;
+import static android.content.Intent.ACTION_POWER_DISCONNECTED;
+import static android.os.BatteryManager.BATTERY_STATUS_CHARGING;
+import static android.os.BatteryManager.BATTERY_STATUS_FULL;
+import static android.os.BatteryManager.EXTRA_STATUS;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Logger.getLogger;
+
+class AndroidBatteryManager implements BatteryManager, Service {
+
+	private static final Logger LOG =
+			getLogger(AndroidBatteryManager.class.getName());
+
+	private final Context appContext;
+	private final EventBus eventBus;
+	private final AtomicBoolean used = new AtomicBoolean(false);
+
+	private volatile BroadcastReceiver batteryReceiver = null;
+
+	@Inject
+	AndroidBatteryManager(Application app, EventBus eventBus) {
+		this.appContext = app.getApplicationContext();
+		this.eventBus = eventBus;
+	}
+
+	@Override
+	public boolean isCharging() {
+		// Get the sticky intent for ACTION_BATTERY_CHANGED
+		IntentFilter filter = new IntentFilter(ACTION_BATTERY_CHANGED);
+		Intent i = appContext.registerReceiver(null, filter);
+		if (i == null) return false;
+		int status = i.getIntExtra(EXTRA_STATUS, -1);
+		return status == BATTERY_STATUS_CHARGING ||
+				status == BATTERY_STATUS_FULL;
+	}
+
+	@Override
+	public void startService() {
+		if (used.getAndSet(true)) throw new IllegalStateException();
+		batteryReceiver = new BatteryReceiver();
+		IntentFilter filter = new IntentFilter();
+		filter.addAction(ACTION_POWER_CONNECTED);
+		filter.addAction(ACTION_POWER_DISCONNECTED);
+		appContext.registerReceiver(batteryReceiver, filter);
+	}
+
+	@Override
+	public void stopService() {
+		if (batteryReceiver != null)
+			appContext.unregisterReceiver(batteryReceiver);
+	}
+
+	private class BatteryReceiver extends BroadcastReceiver {
+
+		@Override
+		public void onReceive(Context ctx, Intent i) {
+			String action = i.getAction();
+			if (LOG.isLoggable(INFO)) LOG.info("Received broadcast " + action);
+			if (ACTION_POWER_CONNECTED.equals(action))
+				eventBus.broadcast(new BatteryEvent(true));
+			else if (ACTION_POWER_DISCONNECTED.equals(action))
+				eventBus.broadcast(new BatteryEvent(false));
+		}
+	}
+}

bramble-android/src/main/java/org/briarproject/bramble/battery/AndroidBatteryModule.java

@@ -0,0 +1,27 @@
+package org.briarproject.bramble.battery;
+
+import org.briarproject.bramble.api.battery.BatteryManager;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class AndroidBatteryModule {
+
+	public static class EagerSingletons {
+		@Inject
+		BatteryManager batteryManager;
+	}
+
+	@Provides
+	@Singleton
+	BatteryManager provideBatteryManager(LifecycleManager lifecycleManager,
+			AndroidBatteryManager batteryManager) {
+		lifecycleManager.registerService(batteryManager);
+		return batteryManager;
+	}
+}

bramble-android/src/main/java/org/briarproject/bramble/network/AndroidNetworkModule.java

@@ -3,6 +3,7 @@ package org.briarproject.bramble.network;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.network.NetworkManager;
 
+import javax.inject.Inject;
 import javax.inject.Singleton;
 
 import dagger.Module;
@@ -11,6 +12,11 @@ import dagger.Provides;
 @Module
 public class AndroidNetworkModule {
 
+	public static class EagerSingletons {
+		@Inject
+		NetworkManager networkManager;
+	}
+
 	@Provides
 	@Singleton
 	NetworkManager provideNetworkManager(LifecycleManager lifecycleManager,

bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/AndroidTorPlugin.java

@@ -6,6 +6,7 @@ import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.os.PowerManager;
 
+import org.briarproject.bramble.api.battery.BatteryManager;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
@@ -41,17 +42,18 @@ class AndroidTorPlugin extends TorPlugin {
 			Context appContext, NetworkManager networkManager,
 			LocationUtils locationUtils, SocketFactory torSocketFactory,
 			Clock clock, ResourceProvider resourceProvider,
-			CircumventionProvider circumventionProvider, Backoff backoff,
+			CircumventionProvider circumventionProvider,
+			BatteryManager batteryManager, Backoff backoff,
 			DuplexPluginCallback callback, String architecture, int maxLatency,
 			int maxIdleTime) {
 		super(ioExecutor, networkManager, locationUtils, torSocketFactory,
-				clock, resourceProvider, circumventionProvider, backoff,
-				callback, architecture, maxLatency, maxIdleTime,
+				clock, resourceProvider, circumventionProvider, batteryManager,
+				backoff, callback, architecture, maxLatency, maxIdleTime,
 				appContext.getDir("tor", MODE_PRIVATE));
 		this.appContext = appContext;
 		PowerManager pm = (PowerManager)
 				appContext.getSystemService(POWER_SERVICE);
-		assert pm != null;
+		if (pm == null) throw new AssertionError();
 		wakeLock = new RenewableWakeLock(pm, scheduler, PARTIAL_WAKE_LOCK,
 				WAKE_LOCK_TAG, 1, MINUTES);
 	}

bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/AndroidTorPluginFactory.java

@@ -3,6 +3,7 @@ package org.briarproject.bramble.plugin.tor;
 import android.content.Context;
 import android.os.Build;
 
+import org.briarproject.bramble.api.battery.BatteryManager;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -48,6 +49,7 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 	private final BackoffFactory backoffFactory;
 	private final ResourceProvider resourceProvider;
 	private final CircumventionProvider circumventionProvider;
+	private final BatteryManager batteryManager;
 	private final Clock clock;
 
 	public AndroidTorPluginFactory(Executor ioExecutor,
@@ -55,7 +57,8 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 			NetworkManager networkManager, LocationUtils locationUtils,
 			EventBus eventBus, SocketFactory torSocketFactory,
 			BackoffFactory backoffFactory, ResourceProvider resourceProvider,
-			CircumventionProvider circumventionProvider, Clock clock) {
+			CircumventionProvider circumventionProvider,
+			BatteryManager batteryManager, Clock clock) {
 		this.ioExecutor = ioExecutor;
 		this.scheduler = scheduler;
 		this.appContext = appContext;
@@ -66,6 +69,7 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 		this.backoffFactory = backoffFactory;
 		this.resourceProvider = resourceProvider;
 		this.circumventionProvider = circumventionProvider;
+		this.batteryManager = batteryManager;
 		this.clock = clock;
 	}
 
@@ -104,8 +108,8 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidTorPlugin plugin = new AndroidTorPlugin(ioExecutor, scheduler,
 				appContext, networkManager, locationUtils, torSocketFactory,
-				clock, resourceProvider, circumventionProvider, backoff,
-				callback, architecture, MAX_LATENCY, MAX_IDLE_TIME);
+				clock, resourceProvider, circumventionProvider, batteryManager,
+				backoff, callback, architecture, MAX_LATENCY, MAX_IDLE_TIME);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

bramble-android/src/main/java/org/briarproject/bramble/util/AndroidUtils.java

@@ -11,15 +11,12 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
-import java.util.logging.Logger;
 
 import static android.content.Context.MODE_PRIVATE;
+import static android.os.Build.VERSION.SDK_INT;
 
 public class AndroidUtils {
 
-	private static final Logger LOG =
-			Logger.getLogger(AndroidUtils.class.getName());
-
 	// Fake Bluetooth address returned by BluetoothAdapter on API 23 and later
 	private static final String FAKE_BLUETOOTH_ADDRESS = "02:00:00:00:00:00";
 
@@ -28,7 +25,7 @@ public class AndroidUtils {
 	@SuppressWarnings("deprecation")
 	public static Collection<String> getSupportedArchitectures() {
 		List<String> abis = new ArrayList<>();
-		if (Build.VERSION.SDK_INT >= 21) {
+		if (SDK_INT >= 21) {
 			abis.addAll(Arrays.asList(Build.SUPPORTED_ABIS));
 		} else {
 			abis.add(Build.CPU_ABI);

bramble-android/witness.gradle

@@ -31,16 +31,21 @@ dependencyVerification {
         'com.android.tools:sdklib:26.2.1:sdklib-26.2.1.jar:248df7ad5eac4aeb6f96c394c76760de4b7b89ac056e54d0c21a739368b91b45',
         'com.google.code.findbugs:jsr305:1.3.9:jsr305-1.3.9.jar:905721a0eea90a81534abb7ee6ef4ea2e5e645fa1def0a5cd88402df1b46c9ed',
         'com.google.code.gson:gson:2.8.0:gson-2.8.0.jar:c6221763bd79c4f1c3dc7f750b5f29a0bb38b367b81314c4f71896e340c40825',
-        'com.google.dagger:dagger-compiler:2.0.2:dagger-compiler-2.0.2.jar:b74bc9de063dd4c6400b232231f2ef5056145b8fbecbf5382012007dd1c071b3',
-        'com.google.dagger:dagger-producers:2.0-beta:dagger-producers-2.0-beta.jar:99ec15e8a0507ba569e7655bc1165ee5e5ca5aa914b3c8f7e2c2458f724edd6b',
-        'com.google.dagger:dagger:2.0.2:dagger-2.0.2.jar:84c0282ed8be73a29e0475d639da030b55dee72369e58dd35ae7d4fe6243dcf9',
+        'com.google.dagger:dagger-compiler:2.19:dagger-compiler-2.19.jar:27a4b202a2de908182edb261f8c0a264e08e5e4733d7514bc7fbf0d31da5c0fc',
+        'com.google.dagger:dagger-producers:2.19:dagger-producers-2.19.jar:a17663abe0fc38b676026950907d4c5f5e2bf338375415861eaff6e3bdb0b768',
+        'com.google.dagger:dagger-spi:2.19:dagger-spi-2.19.jar:e7a6379d82c841f6aac2866948ad1eed716528707814602842a8d844ce04e2e1',
+        'com.google.dagger:dagger:2.19:dagger-2.19.jar:514b6f1e0727c6572e1d65cb27e4ae668b7aeaeb93a29515182965265b609939',
         'com.google.errorprone:error_prone_annotations:2.0.18:error_prone_annotations-2.0.18.jar:cb4cfad870bf563a07199f3ebea5763f0dec440fcda0b318640b1feaa788656b',
-        'com.google.guava:guava:18.0:guava-18.0.jar:d664fbfc03d2e5ce9cab2a44fb01f1d0bf9dfebeccc1a473b1f9ea31f79f6f99',
+        'com.google.errorprone:error_prone_annotations:2.1.3:error_prone_annotations-2.1.3.jar:03d0329547c13da9e17c634d1049ea2ead093925e290567e1a364fd6b1fc7ff8',
+        'com.google.errorprone:javac-shaded:9-dev-r4023-3:javac-shaded-9-dev-r4023-3.jar:65bfccf60986c47fbc17c9ebab0be626afc41741e0a6ec7109e0768817a36f30',
+        'com.google.googlejavaformat:google-java-format:1.5:google-java-format-1.5.jar:aa19ad7850fb85178aa22f2fddb163b84d6ce4d0035872f30d4408195ca1144e',
         'com.google.guava:guava:23.0:guava-23.0.jar:7baa80df284117e5b945b19b98d367a85ea7b7801bd358ff657946c3bd1b6596',
+        'com.google.guava:guava:25.0-jre:guava-25.0-jre.jar:3fd4341776428c7e0e5c18a7c10de129475b69ab9d30aeafbb5c277bb6074fa9',
         'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:40ceb7157feb263949e0f503fe5f71689333a621021aa20ce0d0acee3badaa0f',
         'com.google.jimfs:jimfs:1.1:jimfs-1.1.jar:c4828e28d7c0a930af9387510b3bada7daa5c04d7c25a75c7b8b081f1c257ddd',
         'com.google.protobuf:protobuf-java:3.4.0:protobuf-java-3.4.0.jar:dce7e66b32456a1b1198da0caff3a8acb71548658391e798c79369241e6490a4',
         'com.googlecode.json-simple:json-simple:1.1:json-simple-1.1.jar:2d9484f4c649f708f47f9a479465fc729770ee65617dca3011836602264f6439',
+        'com.squareup:javapoet:1.11.1:javapoet-1.11.1.jar:9cbf2107be499ec6e95afd36b58e3ca122a24166cdd375732e51267d64058e90',
         'com.squareup:javawriter:2.5.0:javawriter-2.5.0.jar:fcfb09fb0ea0aa97d3cfe7ea792398081348e468f126b3603cb3803f240197f0',
         'com.sun.activation:javax.activation:1.2.0:javax.activation-1.2.0.jar:993302b16cd7056f21e779cc577d175a810bb4900ef73cd8fbf2b50f928ba9ce',
         'com.sun.istack:istack-commons-runtime:2.21:istack-commons-runtime-2.21.jar:c33e67a0807095f02a0e2da139412dd7c4f9cc1a4c054b3e434f96831ba950f4',
@@ -63,7 +68,9 @@ dependencyVerification {
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
         'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
+        'org.briarproject:obfs4proxy-android:0.0.7:obfs4proxy-android-0.0.7.zip:abdfb5d889d848de9bf214f9276abbf454808a505b870819eccc9a9e985bf617',
         'org.briarproject:tor-android:0.3.4.8:tor-android-0.3.4.8.zip:989a0352d9d8d8172cd6c2137654e165e5d2beb10ed1211bab3814e224ad1926',
+        'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.codehaus.groovy:groovy-all:2.4.12:groovy-all-2.4.12.jar:6a56af4bd48903d56bec62821876cadefafd007360cc6bd0d8f7aa8d72b38be4',
         'org.codehaus.mojo:animal-sniffer-annotations:1.14:animal-sniffer-annotations-1.14.jar:2068320bd6bad744c3673ab048f67e30bef8f518996fa380033556600669905d',
         'org.glassfish.jaxb:jaxb-core:2.2.11:jaxb-core-2.2.11.jar:37bcaee8ebb04362c8352a5bf6221b86967ecdab5164c696b10b9a2bb587b2aa',

bramble-api/build.gradle

@@ -7,15 +7,13 @@ apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 dependencies {
-	implementation "com.google.dagger:dagger:2.0.2"
+	implementation "com.google.dagger:dagger:2.19"
 	implementation 'com.google.code.findbugs:jsr305:3.0.2'
 
 	testImplementation 'junit:junit:4.12'
 	testImplementation "org.jmock:jmock:2.8.2"
 	testImplementation "org.jmock:jmock-junit4:2.8.2"
 	testImplementation "org.jmock:jmock-legacy:2.8.2"
-	testImplementation "org.hamcrest:hamcrest-library:1.3"
-	testImplementation "org.hamcrest:hamcrest-core:1.3"
 
 	signature 'org.codehaus.mojo.signature:java16:1.1@signature'
 }

bramble-api/src/main/java/org/briarproject/bramble/api/Pair.java

@@ -0,0 +1,26 @@
+package org.briarproject.bramble.api;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class Pair<A, B> {
+
+	private final A first;
+	private final B second;
+
+	public Pair(A first, B second) {
+		this.first = first;
+		this.second = second;
+	}
+
+	public A getFirst() {
+		return first;
+	}
+
+	public B getSecond() {
+		return second;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/battery/BatteryManager.java

@@ -0,0 +1,6 @@
+package org.briarproject.bramble.api.battery;
+
+public interface BatteryManager {
+
+	boolean isCharging();
+}

bramble-api/src/main/java/org/briarproject/bramble/api/battery/event/BatteryEvent.java

@@ -0,0 +1,19 @@
+package org.briarproject.bramble.api.battery.event;
+
+import org.briarproject.bramble.api.event.Event;
+
+/**
+ * An event that is broadcast when the device starts or stops charging.
+ */
+public class BatteryEvent extends Event {
+
+	private final boolean charging;
+
+	public BatteryEvent(boolean charging) {
+		this.charging = charging;
+	}
+
+	public boolean isCharging() {
+		return charging;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/client/BdfIncomingMessageHook.java

@@ -1,7 +1,6 @@
-package org.briarproject.briar.client;
+package org.briarproject.bramble.api.client;
 
 import org.briarproject.bramble.api.FormatException;
-import org.briarproject.bramble.api.client.ClientHelper;
 import org.briarproject.bramble.api.data.BdfDictionary;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.data.MetadataParser;
@@ -12,7 +11,7 @@ import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.InvalidMessageException;
 import org.briarproject.bramble.api.sync.Message;
-import org.briarproject.bramble.api.sync.ValidationManager.IncomingMessageHook;
+import org.briarproject.bramble.api.sync.validation.IncomingMessageHook;
 
 import javax.annotation.concurrent.Immutable;
 
@@ -62,5 +61,4 @@ public abstract class BdfIncomingMessageHook implements IncomingMessageHook {
 			throw new InvalidMessageException(e);
 		}
 	}
-
 }

bramble-api/src/main/java/org/briarproject/bramble/api/client/BdfMessageValidator.java

@@ -9,7 +9,7 @@ import org.briarproject.bramble.api.sync.Group;
 import org.briarproject.bramble.api.sync.InvalidMessageException;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageContext;
-import org.briarproject.bramble.api.sync.ValidationManager.MessageValidator;
+import org.briarproject.bramble.api.sync.validation.MessageValidator;
 import org.briarproject.bramble.api.system.Clock;
 
 import java.util.logging.Logger;

bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactManager.java

@@ -96,6 +96,12 @@ public interface ContactManager {
 	void setContactActive(Transaction txn, ContactId c, boolean active)
 			throws DbException;
 
+	/**
+	 * Sets an alias name for the contact or unsets it if alias is null.
+	 */
+	void setContactAlias(Transaction txn, ContactId c, @Nullable String alias)
+			throws DbException;
+
 	/**
 	 * Sets an alias name for the contact or unsets it if alias is null.
 	 */

bramble-api/src/main/java/org/briarproject/bramble/api/data/BdfStringUtils.java

@@ -0,0 +1,71 @@
+package org.briarproject.bramble.api.data;
+
+import org.briarproject.bramble.api.Bytes;
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import javax.annotation.Nullable;
+
+import static org.briarproject.bramble.api.data.BdfDictionary.NULL_VALUE;
+import static org.briarproject.bramble.util.StringUtils.toHexString;
+
+@NotNullByDefault
+public class BdfStringUtils {
+
+	public static String toString(@Nullable Object o) throws FormatException {
+		return toString(o, 0);
+	}
+
+	private static String toString(@Nullable Object o, int indent)
+			throws FormatException {
+		if (o == null || o == NULL_VALUE) return "null";
+		if (o instanceof Boolean) return o.toString();
+		if (o instanceof Number) return o.toString();
+		if (o instanceof String) return "\"" + o + "\"";
+		if (o instanceof Bytes)
+			return "x" + toHexString(((Bytes) o).getBytes());
+		if (o instanceof byte[])
+			return "x" + toHexString((byte[]) o);
+		if (o instanceof List) {
+			List<?> list = (List) o;
+			StringBuilder sb = new StringBuilder();
+			sb.append("[\n");
+			int i = 0, size = list.size();
+			for (Object e : list) {
+				indent(sb, indent + 1);
+				sb.append(toString(e, indent + 1));
+				if (i++ < size - 1) sb.append(',');
+				sb.append('\n');
+			}
+			indent(sb, indent);
+			sb.append(']');
+			return sb.toString();
+		}
+		if (o instanceof Map) {
+			Map<?, ?> map = (Map) o;
+			StringBuilder sb = new StringBuilder();
+			sb.append("{\n");
+			int i = 0, size = map.size();
+			for (Entry e : map.entrySet()) {
+				indent(sb, indent + 1);
+				sb.append(toString(e.getKey(), indent + 1));
+				sb.append(": ");
+				sb.append(toString(e.getValue(), indent + 1));
+				if (i++ < size - 1) sb.append(',');
+				sb.append('\n');
+			}
+			indent(sb, indent);
+			sb.append('}');
+			return sb.toString();
+		}
+		throw new FormatException();
+	}
+
+	private static void indent(StringBuilder sb, int indent) {
+		for (int i = 0; i < indent; i++) sb.append('\t');
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java

@@ -19,6 +19,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
+import org.briarproject.bramble.api.sync.validation.MessageState;
 import org.briarproject.bramble.api.transport.KeySet;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
@@ -28,8 +29,6 @@ import java.util.Map;
 
 import javax.annotation.Nullable;
 
-import static org.briarproject.bramble.api.sync.ValidationManager.State;
-
 /**
  * Encapsulates the database implementation and exposes high-level operations
  * to other components.
@@ -89,6 +88,14 @@ public interface DatabaseComponent {
 	<R, E extends Exception> R transactionWithResult(boolean readOnly,
 			DbCallable<R, E> task) throws DbException, E;
 
+	/**
+	 * Runs the given task within a transaction and returns the result of the
+	 * task, which may be null.
+	 */
+	@Nullable
+	<R, E extends Exception> R transactionWithNullableResult(boolean readOnly,
+			NullableDbCallable<R, E> task) throws DbException, E;
+
 	/**
 	 * Stores a contact associated with the given local and remote pseudonyms,
 	 * and returns an ID for the contact.
@@ -366,12 +373,12 @@ public interface DatabaseComponent {
 	/**
 	 * Returns the IDs and states of all dependencies of the given message.
 	 * For missing dependencies and dependencies in other groups, the state
-	 * {@link State UNKNOWN} is returned.
+	 * {@link MessageState UNKNOWN} is returned.
 	 * <p/>
 	 * Read-only.
 	 */
-	Map<MessageId, State> getMessageDependencies(Transaction txn, MessageId m)
-			throws DbException;
+	Map<MessageId, MessageState> getMessageDependencies(Transaction txn,
+			MessageId m) throws DbException;
 
 	/**
 	 * Returns the IDs and states of all dependents of the given message.
@@ -380,15 +387,16 @@ public interface DatabaseComponent {
 	 * <p/>
 	 * Read-only.
 	 */
-	Map<MessageId, State> getMessageDependents(Transaction txn, MessageId m)
-			throws DbException;
+	Map<MessageId, MessageState> getMessageDependents(Transaction txn,
+			MessageId m) throws DbException;
 
 	/**
 	 * Gets the validation and delivery state of the given message.
 	 * <p/>
 	 * Read-only.
 	 */
-	State getMessageState(Transaction txn, MessageId m) throws DbException;
+	MessageState getMessageState(Transaction txn, MessageId m)
+			throws DbException;
 
 	/**
 	 * Returns the status of the given delivered message with respect to the
@@ -535,7 +543,7 @@ public interface DatabaseComponent {
 	/**
 	 * Sets the validation and delivery state of the given message.
 	 */
-	void setMessageState(Transaction txn, MessageId m, State state)
+	void setMessageState(Transaction txn, MessageId m, MessageState state)
 			throws DbException;
 
 	/**

bramble-api/src/main/java/org/briarproject/bramble/api/db/DbCallable.java

@@ -1,5 +1,8 @@
 package org.briarproject.bramble.api.db;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
 public interface DbCallable<R, E extends Exception> {
 
 	R call(Transaction txn) throws DbException, E;

bramble-api/src/main/java/org/briarproject/bramble/api/db/DbRunnable.java

@@ -1,5 +1,8 @@
 package org.briarproject.bramble.api.db;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
 public interface DbRunnable<E extends Exception> {
 
 	void run(Transaction txn) throws DbException, E;

bramble-api/src/main/java/org/briarproject/bramble/api/db/NullableDbCallable.java

@@ -0,0 +1,12 @@
+package org.briarproject.bramble.api.db;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+
+@NotNullByDefault
+public interface NullableDbCallable<R, E extends Exception> {
+
+	@Nullable
+	R call(Transaction txn) throws DbException, E;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/identity/AuthorInfo.java

@@ -39,4 +39,18 @@ public class AuthorInfo {
 		return alias;
 	}
 
+	@Override
+	public int hashCode() {
+		int hashCode = status.ordinal();
+		if (alias != null) hashCode += alias.hashCode();
+		return hashCode;
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (!(o instanceof AuthorInfo)) return false;
+		AuthorInfo info = (AuthorInfo) o;
+		return status == info.status &&
+				(alias == null ? info.alias == null : alias.equals(info.alias));
+	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/nullsafety/NullSafety.java

@@ -0,0 +1,15 @@
+package org.briarproject.bramble.api.nullsafety;
+
+import javax.annotation.Nullable;
+
+@NotNullByDefault
+public class NullSafety {
+
+	/**
+	 * Stand-in for `Objects.requireNonNull()`.
+	 */
+	public static <T> T requireNonNull(@Nullable T t) {
+		if (t == null) throw new NullPointerException();
+		return t;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/sync/ValidationManager.java

@@ -1,87 +0,0 @@
-package org.briarproject.bramble.api.sync;
-
-import org.briarproject.bramble.api.crypto.SecretKey;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Metadata;
-import org.briarproject.bramble.api.db.Transaction;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-/**
- * Responsible for managing message validators and passing them messages to
- * validate.
- */
-@NotNullByDefault
-public interface ValidationManager {
-
-	enum State {
-
-		UNKNOWN(0), INVALID(1), PENDING(2), DELIVERED(3);
-
-		private final int value;
-
-		State(int value) {
-			this.value = value;
-		}
-
-		public int getValue() {
-			return value;
-		}
-
-		public static State fromValue(int value) {
-			for (State s : values()) if (s.value == value) return s;
-			throw new IllegalArgumentException();
-		}
-	}
-
-	/**
-	 * Registers the message validator for the given client. This method
-	 * should be called before
-	 * {@link LifecycleManager#startServices(SecretKey)}.
-	 */
-	void registerMessageValidator(ClientId c, int majorVersion,
-			MessageValidator v);
-
-	/**
-	 * Registers the incoming message hook for the given client. The hook will
-	 * be called once for each incoming message that passes validation. This
-	 * method should be called before
-	 * {@link LifecycleManager#startServices(SecretKey)}.
-	 */
-	void registerIncomingMessageHook(ClientId c, int majorVersion,
-			IncomingMessageHook hook);
-
-	interface MessageValidator {
-
-		/**
-		 * Validates the given message and returns its metadata and
-		 * dependencies.
-		 */
-		MessageContext validateMessage(Message m, Group g)
-				throws InvalidMessageException;
-	}
-
-	interface IncomingMessageHook {
-
-		/**
-		 * Called once for each incoming message that passes validation.
-		 *
-		 * @return whether or not this message should be shared
-		 * @throws DbException Should only be used for real database errors.
-		 * If this is thrown, delivery will be attempted again at next startup,
-		 * whereas if an InvalidMessageException is thrown,
-		 * the message will be permanently invalidated.
-		 * @throws InvalidMessageException for any non-database error
-		 * that occurs while handling remotely created data.
-		 * This includes errors that occur while handling locally created data
-		 * in a context controlled by remotely created data
-		 * (for example, parsing the metadata of a dependency
-		 * of an incoming message).
-		 * Throwing this will delete the incoming message and its metadata
-		 * marking it as invalid in the database.
-		 * Never rethrow DbException as InvalidMessageException!
-		 */
-		boolean incomingMessage(Transaction txn, Message m, Metadata meta)
-				throws DbException, InvalidMessageException;
-	}
-}

bramble-api/src/main/java/org/briarproject/bramble/api/sync/event/MessageStateChangedEvent.java

@@ -3,11 +3,10 @@ package org.briarproject.bramble.api.sync.event;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.sync.validation.MessageState;
 
 import javax.annotation.concurrent.Immutable;
 
-import static org.briarproject.bramble.api.sync.ValidationManager.State;
-
 /**
  * An event that is broadcast when a message state changed.
  */
@@ -17,10 +16,10 @@ public class MessageStateChangedEvent extends Event {
 
 	private final MessageId messageId;
 	private final boolean local;
-	private final State state;
+	private final MessageState state;
 
 	public MessageStateChangedEvent(MessageId messageId, boolean local,
-			State state) {
+			MessageState state) {
 		this.messageId = messageId;
 		this.local = local;
 		this.state = state;
@@ -34,7 +33,7 @@ public class MessageStateChangedEvent extends Event {
 		return local;
 	}
 
-	public State getState() {
+	public MessageState getState() {
 		return state;
 	}
 

bramble-api/src/main/java/org/briarproject/bramble/api/sync/validation/IncomingMessageHook.java

@@ -0,0 +1,31 @@
+package org.briarproject.bramble.api.sync.validation;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Metadata;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.sync.InvalidMessageException;
+import org.briarproject.bramble.api.sync.Message;
+
+public interface IncomingMessageHook {
+
+	/**
+	 * Called once for each incoming message that passes validation.
+	 *
+	 * @return whether or not this message should be shared
+	 * @throws DbException Should only be used for real database errors.
+	 * If this is thrown, delivery will be attempted again at next startup,
+	 * whereas if an InvalidMessageException is thrown,
+	 * the message will be permanently invalidated.
+	 * @throws InvalidMessageException for any non-database error
+	 * that occurs while handling remotely created data.
+	 * This includes errors that occur while handling locally created data
+	 * in a context controlled by remotely created data
+	 * (for example, parsing the metadata of a dependency
+	 * of an incoming message).
+	 * Throwing this will delete the incoming message and its metadata
+	 * marking it as invalid in the database.
+	 * Never rethrow DbException as InvalidMessageException!
+	 */
+	boolean incomingMessage(Transaction txn, Message m, Metadata meta)
+			throws DbException, InvalidMessageException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/sync/validation/MessageState.java

@@ -0,0 +1,21 @@
+package org.briarproject.bramble.api.sync.validation;
+
+public enum MessageState {
+
+	UNKNOWN(0), INVALID(1), PENDING(2), DELIVERED(3);
+
+	private final int value;
+
+	MessageState(int value) {
+		this.value = value;
+	}
+
+	public int getValue() {
+		return value;
+	}
+
+	public static MessageState fromValue(int value) {
+		for (MessageState s : values()) if (s.value == value) return s;
+		throw new IllegalArgumentException();
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/sync/validation/MessageValidator.java

@@ -0,0 +1,16 @@
+package org.briarproject.bramble.api.sync.validation;
+
+import org.briarproject.bramble.api.sync.Group;
+import org.briarproject.bramble.api.sync.InvalidMessageException;
+import org.briarproject.bramble.api.sync.Message;
+import org.briarproject.bramble.api.sync.MessageContext;
+
+public interface MessageValidator {
+
+	/**
+	 * Validates the given message and returns its metadata and
+	 * dependencies.
+	 */
+	MessageContext validateMessage(Message m, Group g)
+			throws InvalidMessageException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/sync/validation/ValidationManager.java

@@ -0,0 +1,31 @@
+package org.briarproject.bramble.api.sync.validation;
+
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.ClientId;
+
+/**
+ * Responsible for managing message validators and passing them messages to
+ * validate.
+ */
+@NotNullByDefault
+public interface ValidationManager {
+
+	/**
+	 * Registers the {@link MessageValidator} for the given client. This method
+	 * should be called before
+	 * {@link LifecycleManager#startServices(SecretKey)}.
+	 */
+	void registerMessageValidator(ClientId c, int majorVersion,
+			MessageValidator v);
+
+	/**
+	 * Registers the {@link IncomingMessageHook} for the given client. The hook
+	 * will be called once for each incoming message that passes validation.
+	 * This method should be called before
+	 * {@link LifecycleManager#startServices(SecretKey)}.
+	 */
+	void registerIncomingMessageHook(ClientId c, int majorVersion,
+			IncomingMessageHook hook);
+}

bramble-api/src/main/java/org/briarproject/bramble/util/StringUtils.java

@@ -47,7 +47,7 @@ public class StringUtils {
 		try {
 			return s.getBytes("UTF-8");
 		} catch (UnsupportedEncodingException e) {
-			throw new RuntimeException(e);
+			throw new AssertionError(e);
 		}
 	}
 
@@ -63,7 +63,7 @@ public class StringUtils {
 		try {
 			return decoder.decode(buffer).toString();
 		} catch (CharacterCodingException e) {
-			throw new RuntimeException(e);
+			throw new AssertionError(e);
 		}
 	}
 

bramble-api/src/test/java/org/briarproject/bramble/api/identity/AuthorInfoTest.java

@@ -0,0 +1,42 @@
+package org.briarproject.bramble.api.identity;
+
+import org.briarproject.bramble.test.BrambleTestCase;
+import org.junit.Test;
+
+import static org.briarproject.bramble.api.identity.AuthorInfo.Status.NONE;
+import static org.briarproject.bramble.api.identity.AuthorInfo.Status.VERIFIED;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+
+public class AuthorInfoTest extends BrambleTestCase {
+
+	@Test
+	public void testEquals() {
+		assertEquals(
+				new AuthorInfo(NONE),
+				new AuthorInfo(NONE, null)
+		);
+		assertEquals(
+				new AuthorInfo(NONE, "test"),
+				new AuthorInfo(NONE, "test")
+		);
+
+		assertNotEquals(
+				new AuthorInfo(NONE),
+				new AuthorInfo(VERIFIED)
+		);
+		assertNotEquals(
+				new AuthorInfo(NONE, "test"),
+				new AuthorInfo(NONE)
+		);
+		assertNotEquals(
+				new AuthorInfo(NONE),
+				new AuthorInfo(NONE, "test")
+		);
+		assertNotEquals(
+				new AuthorInfo(NONE, "a"),
+				new AuthorInfo(NONE, "b")
+		);
+	}
+
+}

bramble-api/witness.gradle

@@ -2,7 +2,7 @@ dependencyVerification {
     verify = [
         'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
         'com.google.code.findbugs:jsr305:3.0.2:jsr305-3.0.2.jar:766ad2a0783f2687962c8ad74ceecc38a28b9f72a2d085ee438b7813e928d0c7',
-        'com.google.dagger:dagger:2.0.2:dagger-2.0.2.jar:84c0282ed8be73a29e0475d639da030b55dee72369e58dd35ae7d4fe6243dcf9',
+        'com.google.dagger:dagger:2.19:dagger-2.19.jar:514b6f1e0727c6572e1d65cb27e4ae668b7aeaeb93a29515182965265b609939',
         'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
         'junit:junit:4.12:junit-4.12.jar:59721f0805e223d84b90677887d9ff567dc534d7c502ca903c0c2b17f05c116a',
         'org.apache.ant:ant-launcher:1.9.4:ant-launcher-1.9.4.jar:7bccea20b41801ca17bcbc909a78c835d0f443f12d639c77bd6ae3d05861608d',

bramble-core/build.gradle

@@ -3,10 +3,10 @@ sourceCompatibility = 1.8
 targetCompatibility = 1.8
 
 apply plugin: 'ru.vyarus.animalsniffer'
-apply plugin: 'net.ltgt.apt'
 apply plugin: 'idea'
 apply plugin: 'witness'
 apply from: 'witness.gradle'
+apply from: '../dagger.gradle'
 
 dependencies {
 	implementation project(path: ':bramble-api', configuration: 'default')
@@ -17,7 +17,7 @@ dependencies {
 	implementation 'org.whispersystems:curve25519-java:0.5.0'
 	implementation 'org.briarproject:jtorctl:0.3'
 
-	apt 'com.google.dagger:dagger-compiler:2.0.2'
+	annotationProcessor 'com.google.dagger:dagger-compiler:2.19'
 
 	testImplementation project(path: ':bramble-api', configuration: 'testOutput')
 	testImplementation 'org.hsqldb:hsqldb:2.3.5' // The last version that supports Java 1.6
@@ -25,10 +25,8 @@ dependencies {
 	testImplementation "org.jmock:jmock:2.8.2"
 	testImplementation "org.jmock:jmock-junit4:2.8.2"
 	testImplementation "org.jmock:jmock-legacy:2.8.2"
-	testImplementation "org.hamcrest:hamcrest-library:1.3"
-	testImplementation "org.hamcrest:hamcrest-core:1.3"
 
-	testApt 'com.google.dagger:dagger-compiler:2.0.2'
+	testAnnotationProcessor 'com.google.dagger:dagger-compiler:2.19'
 
 	signature 'org.codehaus.mojo.signature:java16:1.1@signature'
 }

bramble-core/src/main/java/org/briarproject/bramble/BrambleCoreEagerSingletons.java

@@ -8,7 +8,7 @@ import org.briarproject.bramble.lifecycle.LifecycleModule;
 import org.briarproject.bramble.plugin.PluginModule;
 import org.briarproject.bramble.properties.PropertiesModule;
 import org.briarproject.bramble.reporting.ReportingModule;
-import org.briarproject.bramble.sync.SyncModule;
+import org.briarproject.bramble.sync.validation.ValidationModule;
 import org.briarproject.bramble.system.SystemModule;
 import org.briarproject.bramble.transport.TransportModule;
 import org.briarproject.bramble.versioning.VersioningModule;
@@ -31,11 +31,11 @@ public interface BrambleCoreEagerSingletons {
 
 	void inject(ReportingModule.EagerSingletons init);
 
-	void inject(SyncModule.EagerSingletons init);
-
 	void inject(SystemModule.EagerSingletons init);
 
 	void inject(TransportModule.EagerSingletons init);
 
+	void inject(ValidationModule.EagerSingletons init);
+
 	void inject(VersioningModule.EagerSingletons init);
 }

bramble-core/src/main/java/org/briarproject/bramble/BrambleCoreModule.java

@@ -19,6 +19,7 @@ import org.briarproject.bramble.reporting.ReportingModule;
 import org.briarproject.bramble.settings.SettingsModule;
 import org.briarproject.bramble.socks.SocksModule;
 import org.briarproject.bramble.sync.SyncModule;
+import org.briarproject.bramble.sync.validation.ValidationModule;
 import org.briarproject.bramble.system.SystemModule;
 import org.briarproject.bramble.transport.TransportModule;
 import org.briarproject.bramble.versioning.VersioningModule;
@@ -47,6 +48,7 @@ import dagger.Module;
 		SyncModule.class,
 		SystemModule.class,
 		TransportModule.class,
+		ValidationModule.class,
 		VersioningModule.class
 })
 public class BrambleCoreModule {
@@ -60,9 +62,9 @@ public class BrambleCoreModule {
 		c.inject(new PluginModule.EagerSingletons());
 		c.inject(new PropertiesModule.EagerSingletons());
 		c.inject(new ReportingModule.EagerSingletons());
-		c.inject(new SyncModule.EagerSingletons());
 		c.inject(new SystemModule.EagerSingletons());
 		c.inject(new TransportModule.EagerSingletons());
+		c.inject(new ValidationModule.EagerSingletons());
 		c.inject(new VersioningModule.EagerSingletons());
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/battery/DefaultBatteryManagerModule.java

@@ -0,0 +1,19 @@
+package org.briarproject.bramble.battery;
+
+import org.briarproject.bramble.api.battery.BatteryManager;
+
+import dagger.Module;
+import dagger.Provides;
+
+/**
+ * Provides a default implementation of {@link BatteryManager} for systems
+ * without batteries.
+ */
+@Module
+public class DefaultBatteryManagerModule {
+
+	@Provides
+	BatteryManager provideBatteryManager() {
+		return () -> false;
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/client/ClientHelperImpl.java

@@ -82,13 +82,7 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public void addLocalMessage(Message m, BdfDictionary metadata,
 			boolean shared) throws DbException, FormatException {
-		Transaction txn = db.startTransaction(false);
-		try {
-			addLocalMessage(txn, m, metadata, shared);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
+		db.transaction(false, txn -> addLocalMessage(txn, m, metadata, shared));
 	}
 
 	@Override
@@ -113,15 +107,7 @@ class ClientHelperImpl implements ClientHelper {
 
 	@Override
 	public Message getMessage(MessageId m) throws DbException {
-		Message message;
-		Transaction txn = db.startTransaction(true);
-		try {
-			message = getMessage(txn, m);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return message;
+		return db.transactionWithResult(true, txn -> getMessage(txn, m));
 	}
 
 	@Override
@@ -132,15 +118,7 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public BdfList getMessageAsList(MessageId m) throws DbException,
 			FormatException {
-		BdfList list;
-		Transaction txn = db.startTransaction(true);
-		try {
-			list = getMessageAsList(txn, m);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return list;
+		return db.transactionWithResult(true, txn -> getMessageAsList(txn, m));
 	}
 
 	@Override
@@ -152,15 +130,8 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public BdfDictionary getGroupMetadataAsDictionary(GroupId g)
 			throws DbException, FormatException {
-		BdfDictionary dictionary;
-		Transaction txn = db.startTransaction(true);
-		try {
-			dictionary = getGroupMetadataAsDictionary(txn, g);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return dictionary;
+		return db.transactionWithResult(true, txn ->
+				getGroupMetadataAsDictionary(txn, g));
 	}
 
 	@Override
@@ -173,15 +144,8 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public BdfDictionary getMessageMetadataAsDictionary(MessageId m)
 			throws DbException, FormatException {
-		BdfDictionary dictionary;
-		Transaction txn = db.startTransaction(true);
-		try {
-			dictionary = getMessageMetadataAsDictionary(txn, m);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return dictionary;
+		return db.transactionWithResult(true, txn ->
+				getMessageMetadataAsDictionary(txn, m));
 	}
 
 	@Override
@@ -194,15 +158,8 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public Map<MessageId, BdfDictionary> getMessageMetadataAsDictionary(
 			GroupId g) throws DbException, FormatException {
-		Map<MessageId, BdfDictionary> map;
-		Transaction txn = db.startTransaction(true);
-		try {
-			map = getMessageMetadataAsDictionary(txn, g);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return map;
+		return db.transactionWithResult(true, txn ->
+				getMessageMetadataAsDictionary(txn, g));
 	}
 
 	@Override
@@ -219,15 +176,8 @@ class ClientHelperImpl implements ClientHelper {
 	public Map<MessageId, BdfDictionary> getMessageMetadataAsDictionary(
 			GroupId g, BdfDictionary query) throws DbException,
 			FormatException {
-		Map<MessageId, BdfDictionary> map;
-		Transaction txn = db.startTransaction(true);
-		try {
-			map = getMessageMetadataAsDictionary(txn, g, query);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return map;
+		return db.transactionWithResult(true, txn ->
+				getMessageMetadataAsDictionary(txn, g, query));
 	}
 
 	@Override
@@ -245,13 +195,7 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public void mergeGroupMetadata(GroupId g, BdfDictionary metadata)
 			throws DbException, FormatException {
-		Transaction txn = db.startTransaction(false);
-		try {
-			mergeGroupMetadata(txn, g, metadata);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
+		db.transaction(false, txn -> mergeGroupMetadata(txn, g, metadata));
 	}
 
 	@Override
@@ -263,13 +207,7 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public void mergeMessageMetadata(MessageId m, BdfDictionary metadata)
 			throws DbException, FormatException {
-		Transaction txn = db.startTransaction(false);
-		try {
-			mergeMessageMetadata(txn, m, metadata);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
+		db.transaction(false, txn -> mergeMessageMetadata(txn, m, metadata));
 	}
 
 	@Override

bramble-core/src/main/java/org/briarproject/bramble/contact/ContactExchangeTaskImpl.java

@@ -13,7 +13,6 @@ import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.db.ContactExistsException;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
@@ -158,7 +157,8 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 				streamWriterFactory.createContactExchangeStreamWriter(out,
 						alice ? aliceHeaderKey : bobHeaderKey);
 		RecordWriter recordWriter =
-				recordWriterFactory.createRecordWriter(streamWriter.getOutputStream());
+				recordWriterFactory
+						.createRecordWriter(streamWriter.getOutputStream());
 
 		// Derive the nonces to be signed
 		byte[] aliceNonce = crypto.mac(ALICE_NONCE_LABEL, masterSecret,
@@ -287,19 +287,14 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 	private ContactId addContact(Author remoteAuthor, long timestamp,
 			Map<TransportId, TransportProperties> remoteProperties)
 			throws DbException {
-		ContactId contactId;
-		Transaction txn = db.startTransaction(false);
-		try {
-			contactId = contactManager.addContact(txn, remoteAuthor,
+		return db.transactionWithResult(false, txn -> {
+			ContactId contactId = contactManager.addContact(txn, remoteAuthor,
 					localAuthor.getId(), masterSecret, timestamp, alice,
 					true, true);
 			transportPropertyManager.addRemoteProperties(txn, contactId,
 					remoteProperties);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return contactId;
+			return contactId;
+		});
 	}
 
 	private void tryToClose(DuplexTransportConnection conn) {

bramble-core/src/main/java/org/briarproject/bramble/contact/ContactManagerImpl.java

@@ -79,42 +79,21 @@ class ContactManagerImpl implements ContactManager {
 	public ContactId addContact(Author remote, AuthorId local, SecretKey master,
 			long timestamp, boolean alice, boolean verified, boolean active)
 			throws DbException {
-		ContactId c;
-		Transaction txn = db.startTransaction(false);
-		try {
-			c = addContact(txn, remote, local, master, timestamp, alice,
-					verified, active);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return c;
+		return db.transactionWithResult(false, txn ->
+				addContact(txn, remote, local, master, timestamp, alice,
+						verified, active));
 	}
 
 	@Override
 	public Contact getContact(ContactId c) throws DbException {
-		Contact contact;
-		Transaction txn = db.startTransaction(true);
-		try {
-			contact = db.getContact(txn, c);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return contact;
+		return db.transactionWithResult(true, txn -> db.getContact(txn, c));
 	}
 
 	@Override
 	public Contact getContact(AuthorId remoteAuthorId, AuthorId localAuthorId)
 			throws DbException {
-		Transaction txn = db.startTransaction(true);
-		try {
-			Contact c = getContact(txn, remoteAuthorId, localAuthorId);
-			db.commitTransaction(txn);
-			return c;
-		} finally {
-			db.endTransaction(txn);
-		}
+		return db.transactionWithResult(true, txn ->
+				getContact(txn, remoteAuthorId, localAuthorId));
 	}
 
 	@Override
@@ -132,14 +111,8 @@ class ContactManagerImpl implements ContactManager {
 
 	@Override
 	public Collection<Contact> getActiveContacts() throws DbException {
-		Collection<Contact> contacts;
-		Transaction txn = db.startTransaction(true);
-		try {
-			contacts = db.getContacts(txn);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
+		Collection<Contact> contacts =
+				db.transactionWithResult(true, db::getContacts);
 		List<Contact> active = new ArrayList<>(contacts.size());
 		for (Contact c : contacts) if (c.isActive()) active.add(c);
 		return active;
@@ -147,13 +120,7 @@ class ContactManagerImpl implements ContactManager {
 
 	@Override
 	public void removeContact(ContactId c) throws DbException {
-		Transaction txn = db.startTransaction(false);
-		try {
-			removeContact(txn, c);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
+		db.transaction(false, txn -> removeContact(txn, c));
 	}
 
 	@Override
@@ -163,14 +130,20 @@ class ContactManagerImpl implements ContactManager {
 	}
 
 	@Override
-	public void setContactAlias(ContactId c, @Nullable String alias)
-			throws DbException {
+	public void setContactAlias(Transaction txn, ContactId c,
+			@Nullable String alias) throws DbException {
 		if (alias != null) {
 			int aliasLength = toUtf8(alias).length;
 			if (aliasLength == 0 || aliasLength > MAX_AUTHOR_NAME_LENGTH)
 				throw new IllegalArgumentException();
 		}
-		db.transaction(false, txn -> db.setContactAlias(txn, c, alias));
+		db.setContactAlias(txn, c, alias);
+	}
+
+	@Override
+	public void setContactAlias(ContactId c, @Nullable String alias)
+			throws DbException {
+		db.transaction(false, txn -> setContactAlias(txn, c, alias));
 	}
 
 	@Override
@@ -182,15 +155,8 @@ class ContactManagerImpl implements ContactManager {
 	@Override
 	public boolean contactExists(AuthorId remoteAuthorId,
 			AuthorId localAuthorId) throws DbException {
-		boolean exists;
-		Transaction txn = db.startTransaction(true);
-		try {
-			exists = contactExists(txn, remoteAuthorId, localAuthorId);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return exists;
+		return db.transactionWithResult(true, txn ->
+				contactExists(txn, remoteAuthorId, localAuthorId));
 	}
 
 	@Override

bramble-core/src/main/java/org/briarproject/bramble/data/BdfReaderImpl.java

@@ -29,6 +29,7 @@ import static org.briarproject.bramble.data.Types.STRING_16;
 import static org.briarproject.bramble.data.Types.STRING_32;
 import static org.briarproject.bramble.data.Types.STRING_8;
 import static org.briarproject.bramble.data.Types.TRUE;
+import static org.briarproject.bramble.util.StringUtils.fromUtf8;
 
 @NotThreadSafe
 @NotNullByDefault
@@ -253,7 +254,7 @@ class BdfReaderImpl implements BdfReader {
 		if (length < 0 || length > maxBufferSize) throw new FormatException();
 		if (length == 0) return "";
 		readIntoBuffer(length);
-		return new String(buf, 0, length, "UTF-8");
+		return fromUtf8(buf, 0, length);
 	}
 
 	private int readStringLength() throws IOException {

bramble-core/src/main/java/org/briarproject/bramble/db/Database.java

@@ -22,7 +22,7 @@ import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
-import org.briarproject.bramble.api.sync.ValidationManager.State;
+import org.briarproject.bramble.api.sync.validation.MessageState;
 import org.briarproject.bramble.api.transport.KeySet;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
@@ -106,7 +106,7 @@ interface Database<T> {
 	 * @param sender the contact from whom the message was received, or null
 	 * if the message was created locally.
 	 */
-	void addMessage(T txn, Message m, State state, boolean shared,
+	void addMessage(T txn, Message m, MessageState state, boolean shared,
 			@Nullable ContactId sender) throws DbException;
 
 	/**
@@ -114,7 +114,7 @@ interface Database<T> {
 	 * in the given state.
 	 */
 	void addMessageDependency(T txn, Message dependent, MessageId dependency,
-			State dependentState) throws DbException;
+			MessageState dependentState) throws DbException;
 
 	/**
 	 * Records that a message has been offered by the given contact.
@@ -310,11 +310,11 @@ interface Database<T> {
 	/**
 	 * Returns the IDs and states of all dependencies of the given message.
 	 * For missing dependencies and dependencies in other groups, the state
-	 * {@link State UNKNOWN} is returned.
+	 * {@link MessageState UNKNOWN} is returned.
 	 * <p/>
 	 * Read-only.
 	 */
-	Map<MessageId, State> getMessageDependencies(T txn, MessageId m)
+	Map<MessageId, MessageState> getMessageDependencies(T txn, MessageId m)
 			throws DbException;
 
 	/**
@@ -324,7 +324,7 @@ interface Database<T> {
 	 * <p/>
 	 * Read-only.
 	 */
-	Map<MessageId, State> getMessageDependents(T txn, MessageId m)
+	Map<MessageId, MessageState> getMessageDependents(T txn, MessageId m)
 			throws DbException;
 
 	/**
@@ -383,7 +383,7 @@ interface Database<T> {
 	 * <p/>
 	 * Read-only.
 	 */
-	State getMessageState(T txn, MessageId m) throws DbException;
+	MessageState getMessageState(T txn, MessageId m) throws DbException;
 
 	/**
 	 * Returns the status of all delivered messages in the given group with
@@ -637,7 +637,8 @@ interface Database<T> {
 	/**
 	 * Sets the validation and delivery state of the given message.
 	 */
-	void setMessageState(T txn, MessageId m, State state) throws DbException;
+	void setMessageState(T txn, MessageId m, MessageState state)
+			throws DbException;
 
 	/**
 	 * Sets the reordering window for the given key set and transport in the

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseComponentImpl.java

@@ -19,6 +19,7 @@ import org.briarproject.bramble.api.db.NoSuchGroupException;
 import org.briarproject.bramble.api.db.NoSuchLocalAuthorException;
 import org.briarproject.bramble.api.db.NoSuchMessageException;
 import org.briarproject.bramble.api.db.NoSuchTransportException;
+import org.briarproject.bramble.api.db.NullableDbCallable;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
@@ -42,7 +43,6 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
-import org.briarproject.bramble.api.sync.ValidationManager.State;
 import org.briarproject.bramble.api.sync.event.GroupAddedEvent;
 import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
 import org.briarproject.bramble.api.sync.event.GroupVisibilityUpdatedEvent;
@@ -54,6 +54,7 @@ import org.briarproject.bramble.api.sync.event.MessageToAckEvent;
 import org.briarproject.bramble.api.sync.event.MessageToRequestEvent;
 import org.briarproject.bramble.api.sync.event.MessagesAckedEvent;
 import org.briarproject.bramble.api.sync.event.MessagesSentEvent;
+import org.briarproject.bramble.api.sync.validation.MessageState;
 import org.briarproject.bramble.api.transport.KeySet;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeys;
@@ -74,8 +75,8 @@ import javax.inject.Inject;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.DELIVERED;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.UNKNOWN;
+import static org.briarproject.bramble.api.sync.validation.MessageState.DELIVERED;
+import static org.briarproject.bramble.api.sync.validation.MessageState.UNKNOWN;
 import static org.briarproject.bramble.db.DatabaseConstants.MAX_OFFERED_MESSAGES;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -193,6 +194,20 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		}
 	}
 
+	@Override
+	public <R, E extends Exception> R transactionWithNullableResult(
+			boolean readOnly, NullableDbCallable<R, E> task)
+			throws DbException, E {
+		Transaction txn = startTransaction(readOnly);
+		try {
+			R result = task.call(txn);
+			commitTransaction(txn);
+			return result;
+		} finally {
+			endTransaction(txn);
+		}
+	}
+
 	private T unbox(Transaction transaction) {
 		if (transaction.isCommitted()) throw new IllegalStateException();
 		return txnClass.cast(transaction.unbox());
@@ -564,7 +579,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public State getMessageState(Transaction transaction, MessageId m)
+	public MessageState getMessageState(Transaction transaction, MessageId m)
 			throws DbException {
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, m))
@@ -604,8 +619,8 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public Map<MessageId, State> getMessageDependencies(Transaction transaction,
-			MessageId m) throws DbException {
+	public Map<MessageId, MessageState> getMessageDependencies(
+			Transaction transaction, MessageId m) throws DbException {
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, m))
 			throw new NoSuchMessageException();
@@ -613,8 +628,8 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public Map<MessageId, State> getMessageDependents(Transaction transaction,
-			MessageId m) throws DbException {
+	public Map<MessageId, MessageState> getMessageDependents(
+			Transaction transaction, MessageId m) throws DbException {
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, m))
 			throw new NoSuchMessageException();
@@ -861,7 +876,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 
 	@Override
 	public void setContactAlias(Transaction transaction, ContactId c,
-			String alias) throws DbException {
+			@Nullable String alias) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
@@ -903,7 +918,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 
 	@Override
 	public void setMessageState(Transaction transaction, MessageId m,
-			State state) throws DbException {
+			MessageState state) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, m))
@@ -920,10 +935,10 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, dependent.getId()))
 			throw new NoSuchMessageException();
-		State dependentState = db.getMessageState(txn, dependent.getId());
+		MessageState dependentState =
+				db.getMessageState(txn, dependent.getId());
 		for (MessageId dependency : dependencies) {
-			db.addMessageDependency(txn, dependent, dependency,
-					dependentState);
+			db.addMessageDependency(txn, dependent, dependency, dependentState);
 		}
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseTypes.java

@@ -3,7 +3,7 @@ package org.briarproject.bramble.db;
 class DatabaseTypes {
 
 	private final String hashType, secretType, binaryType;
-    private final String counterType, stringType;
+	private final String counterType, stringType;
 
 	public DatabaseTypes(String hashType, String secretType, String binaryType,
 			String counterType, String stringType) {
@@ -17,11 +17,11 @@ class DatabaseTypes {
 	/**
 	 * Replaces database type placeholders in a statement with the actual types.
 	 * These placeholders are currently supported:
-	 *	<li> _HASH
-	 *	<li> _SECRET
-	 *	<li> _BINARY
-	 *	<li> _COUNTER
-	 *	<li> _STRING
+	 * <li> _HASH
+	 * <li> _SECRET
+	 * <li> _BINARY
+	 * <li> _COUNTER
+	 * <li> _STRING
 	 */
 	String replaceTypes(String s) {
 		s = s.replaceAll("_HASH", hashType);

bramble-core/src/main/java/org/briarproject/bramble/db/JdbcDatabase.java

@@ -24,7 +24,7 @@ import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
-import org.briarproject.bramble.api.sync.ValidationManager.State;
+import org.briarproject.bramble.api.sync.validation.MessageState;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.transport.IncomingKeys;
 import org.briarproject.bramble.api.transport.KeySet;
@@ -64,9 +64,9 @@ import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
 import static org.briarproject.bramble.api.sync.Group.Visibility.VISIBLE;
 import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.DELIVERED;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.PENDING;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.UNKNOWN;
+import static org.briarproject.bramble.api.sync.validation.MessageState.DELIVERED;
+import static org.briarproject.bramble.api.sync.validation.MessageState.PENDING;
+import static org.briarproject.bramble.api.sync.validation.MessageState.UNKNOWN;
 import static org.briarproject.bramble.db.DatabaseConstants.DB_SETTINGS_NAMESPACE;
 import static org.briarproject.bramble.db.DatabaseConstants.LAST_COMPACTED_KEY;
 import static org.briarproject.bramble.db.DatabaseConstants.MAX_COMPACTION_INTERVAL_MS;
@@ -724,7 +724,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			while (rs.next()) {
 				MessageId id = new MessageId(rs.getBytes(1));
 				long timestamp = rs.getLong(2);
-				State state = State.fromValue(rs.getInt(3));
+				MessageState state = MessageState.fromValue(rs.getInt(3));
 				boolean messageShared = rs.getBoolean(4);
 				int length = rs.getInt(5);
 				boolean deleted = rs.getBoolean(6);
@@ -767,7 +767,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public void addMessage(Connection txn, Message m, State state,
+	public void addMessage(Connection txn, Message m, MessageState state,
 			boolean messageShared, @Nullable ContactId sender)
 			throws DbException {
 		PreparedStatement ps = null;
@@ -847,7 +847,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	private void addStatus(Connection txn, MessageId m, ContactId c, GroupId g,
-			long timestamp, int length, State state, boolean groupShared,
+			long timestamp, int length, MessageState state, boolean groupShared,
 			boolean messageShared, boolean deleted, boolean seen)
 			throws DbException {
 		PreparedStatement ps = null;
@@ -880,7 +880,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	@Override
 	public void addMessageDependency(Connection txn, Message dependent,
-			MessageId dependency, State dependentState) throws DbException {
+			MessageId dependency, MessageState dependentState)
+			throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
@@ -891,9 +892,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.setBytes(1, dependency.getBytes());
 			ps.setBytes(2, dependent.getGroupId().getBytes());
 			rs = ps.executeQuery();
-			State dependencyState = null;
+			MessageState dependencyState = null;
 			if (rs.next()) {
-				dependencyState = State.fromValue(rs.getInt(1));
+				dependencyState = MessageState.fromValue(rs.getInt(1));
 				if (rs.next()) throw new DbStateException();
 			}
 			rs.close();
@@ -1813,7 +1814,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public Map<MessageId, State> getMessageDependencies(Connection txn,
+	public Map<MessageId, MessageState> getMessageDependencies(Connection txn,
 			MessageId m) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
@@ -1824,10 +1825,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			rs = ps.executeQuery();
-			Map<MessageId, State> dependencies = new HashMap<>();
+			Map<MessageId, MessageState> dependencies = new HashMap<>();
 			while (rs.next()) {
 				MessageId dependency = new MessageId(rs.getBytes(1));
-				State state = State.fromValue(rs.getInt(2));
+				MessageState state = MessageState.fromValue(rs.getInt(2));
 				if (rs.wasNull())
 					state = UNKNOWN; // Missing or in a different group
 				dependencies.put(dependency, state);
@@ -1843,7 +1844,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public Map<MessageId, State> getMessageDependents(Connection txn,
+	public Map<MessageId, MessageState> getMessageDependents(Connection txn,
 			MessageId m) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
@@ -1857,10 +1858,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			rs = ps.executeQuery();
-			Map<MessageId, State> dependents = new HashMap<>();
+			Map<MessageId, MessageState> dependents = new HashMap<>();
 			while (rs.next()) {
 				MessageId dependent = new MessageId(rs.getBytes(1));
-				State state = State.fromValue(rs.getInt(2));
+				MessageState state = MessageState.fromValue(rs.getInt(2));
 				dependents.put(dependent, state);
 			}
 			rs.close();
@@ -1874,7 +1875,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public State getMessageState(Connection txn, MessageId m)
+	public MessageState getMessageState(Connection txn, MessageId m)
 			throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
@@ -1884,7 +1885,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.setBytes(1, m.getBytes());
 			rs = ps.executeQuery();
 			if (!rs.next()) throw new DbStateException();
-			State state = State.fromValue(rs.getInt(1));
+			MessageState state = MessageState.fromValue(rs.getInt(1));
 			if (rs.next()) throw new DbStateException();
 			rs.close();
 			ps.close();
@@ -2032,7 +2033,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	private Collection<MessageId> getMessagesInState(Connection txn,
-			State state) throws DbException {
+			MessageState state) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
@@ -2359,7 +2360,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			rs = ps.executeQuery();
 			if (!rs.next()) throw new DbStateException();
 			GroupId g = new GroupId(rs.getBytes(1));
-			State state = State.fromValue(rs.getInt(2));
+			MessageState state = MessageState.fromValue(rs.getInt(2));
 			rs.close();
 			ps.close();
 			// Insert any keys that don't already exist
@@ -2865,7 +2866,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public void setMessageState(Connection txn, MessageId m, State state)
+	public void setMessageState(Connection txn, MessageId m, MessageState state)
 			throws DbException {
 		PreparedStatement ps = null;
 		try {

bramble-core/src/main/java/org/briarproject/bramble/db/Migration40_41.java

@@ -39,7 +39,7 @@ class Migration40_41 implements Migration<Connection> {
 		try {
 			s = txn.createStatement();
 			s.execute("ALTER TABLE contacts"
-					+ dbTypes.replaceTypes(" ADD alias VARCHAR"));
+					+ dbTypes.replaceTypes(" ADD alias _STRING"));
 		} catch (SQLException e) {
 			tryToClose(s);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/identity/IdentityManagerImpl.java

@@ -67,27 +67,16 @@ class IdentityManagerImpl implements IdentityManager {
 			LOG.info("No local author to store");
 			return;
 		}
-		Transaction txn = db.startTransaction(false);
-		try {
-			db.addLocalAuthor(txn, cached);
-			db.commitTransaction(txn);
-			LOG.info("Local author stored");
-		} finally {
-			db.endTransaction(txn);
-		}
+		db.transaction(false, txn -> db.addLocalAuthor(txn, cached));
+		LOG.info("Local author stored");
 	}
 
 	@Override
 	public LocalAuthor getLocalAuthor() throws DbException {
 		if (cachedAuthor == null) {
-			Transaction txn = db.startTransaction(true);
-			try {
-				cachedAuthor = loadLocalAuthor(txn);
-				LOG.info("Local author loaded");
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
+			cachedAuthor =
+					db.transactionWithResult(true, this::loadLocalAuthor);
+			LOG.info("Local author loaded");
 		}
 		LocalAuthor cached = cachedAuthor;
 		if (cached == null) throw new AssertionError();

bramble-core/src/main/java/org/briarproject/bramble/lifecycle/LifecycleManagerImpl.java

@@ -6,7 +6,6 @@ import org.briarproject.bramble.api.db.DataTooOldException;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.MigrationListener;
-import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
@@ -115,20 +114,16 @@ class LifecycleManagerImpl implements LifecycleManager, MigrationListener {
 			dbLatch.countDown();
 			eventBus.broadcast(new LifecycleEvent(STARTING_SERVICES));
 
-			Transaction txn = db.startTransaction(false);
-			try {
+			db.transaction(false, txn -> {
 				for (Client c : clients) {
-					start = now();
+					long start1 = now();
 					c.createLocalState(txn);
 					if (LOG.isLoggable(FINE)) {
 						logDuration(LOG, "Starting client "
-								+ c.getClass().getSimpleName(), start);
+								+ c.getClass().getSimpleName(), start1);
 					}
 				}
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
+			});
 			for (Service s : services) {
 				start = now();
 				s.startService();

bramble-core/src/main/java/org/briarproject/bramble/plugin/tor/TorPlugin.java

@@ -4,6 +4,8 @@ import net.freehaven.tor.control.EventHandler;
 import net.freehaven.tor.control.TorControlConnection;
 
 import org.briarproject.bramble.PoliteExecutor;
+import org.briarproject.bramble.api.battery.BatteryManager;
+import org.briarproject.bramble.api.battery.event.BatteryEvent;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.event.Event;
@@ -96,13 +98,14 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private final LocationUtils locationUtils;
 	private final SocketFactory torSocketFactory;
 	private final Clock clock;
+	private final BatteryManager batteryManager;
 	private final Backoff backoff;
 	private final DuplexPluginCallback callback;
 	private final String architecture;
 	private final CircumventionProvider circumventionProvider;
 	private final ResourceProvider resourceProvider;
 	private final int maxLatency, maxIdleTime, socketTimeout;
-	private final File torDirectory, torFile, geoIpFile, configFile;
+	private final File torDirectory, torFile, geoIpFile, obfs4File, configFile;
 	private final File doneFile, cookieFile;
 	private final ConnectionStatus connectionStatus;
 	private final AtomicBoolean used = new AtomicBoolean(false);
@@ -121,7 +124,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	TorPlugin(Executor ioExecutor, NetworkManager networkManager,
 			LocationUtils locationUtils, SocketFactory torSocketFactory,
 			Clock clock, ResourceProvider resourceProvider,
-			CircumventionProvider circumventionProvider, Backoff backoff,
+			CircumventionProvider circumventionProvider,
+			BatteryManager batteryManager, Backoff backoff,
 			DuplexPluginCallback callback, String architecture, int maxLatency,
 			int maxIdleTime, File torDirectory) {
 		this.ioExecutor = ioExecutor;
@@ -131,6 +135,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		this.clock = clock;
 		this.resourceProvider = resourceProvider;
 		this.circumventionProvider = circumventionProvider;
+		this.batteryManager = batteryManager;
 		this.backoff = backoff;
 		this.callback = callback;
 		this.architecture = architecture;
@@ -142,6 +147,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		this.torDirectory = torDirectory;
 		torFile = new File(torDirectory, "tor");
 		geoIpFile = new File(torDirectory, "geoip");
+		obfs4File = new File(torDirectory, "obfs4proxy");
 		configFile = new File(torDirectory, "torrc");
 		doneFile = new File(torDirectory, "done");
 		cookieFile = new File(torDirectory, ".tor/control_auth_cookie");
@@ -260,7 +266,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			throw new PluginException(e);
 		}
 		// Check whether we're online
-		updateConnectionStatus(networkManager.getNetworkStatus());
+		updateConnectionStatus(networkManager.getNetworkStatus(),
+				batteryManager.isCharging());
 		// Bind a server socket to receive incoming hidden service connections
 		bind();
 	}
@@ -284,6 +291,12 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			in = getGeoIpInputStream();
 			out = new FileOutputStream(geoIpFile);
 			IoUtils.copyAndClose(in, out);
+			// Unzip the Obfs4 proxy to the filesystem
+			in = getObfs4InputStream();
+			out = new FileOutputStream(obfs4File);
+			IoUtils.copyAndClose(in, out);
+			// Make the Obfs4 proxy executable
+			if (!obfs4File.setExecutable(true, true)) throw new IOException();
 			// Copy the config file to the filesystem
 			in = getConfigInputStream();
 			out = new FileOutputStream(configFile);
@@ -314,6 +327,16 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		return zin;
 	}
 
+	private InputStream getObfs4InputStream() throws IOException {
+		if (LOG.isLoggable(INFO))
+			LOG.info("Installing obfs4proxy binary for " + architecture);
+		InputStream in = resourceProvider
+				.getResourceInputStream("obfs4proxy_" + architecture, ".zip");
+		ZipInputStream zin = new ZipInputStream(in);
+		if (zin.getNextEntry() == null) throw new IOException();
+		return zin;
+	}
+
 	private InputStream getConfigInputStream() {
 		return getClass().getClassLoader().getResourceAsStream("torrc");
 	}
@@ -472,6 +495,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		if (enable) {
 			Collection<String> conf = new ArrayList<>();
 			conf.add("UseBridges 1");
+			conf.add("ClientTransportPlugin obfs4 exec " +
+					obfs4File.getAbsolutePath());
 			conf.addAll(circumventionProvider.getBridges());
 			controlConnection.setConf(conf);
 		} else {
@@ -609,7 +634,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			LOG.info("OR connection " + status + " " + orName);
 		if (status.equals("CLOSED") || status.equals("FAILED")) {
 			// Check whether we've lost connectivity
-			updateConnectionStatus(networkManager.getNetworkStatus());
+			updateConnectionStatus(networkManager.getNetworkStatus(),
+					batteryManager.isCharging());
 		}
 	}
 
@@ -647,10 +673,15 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				// Works around a bug introduced in Tor 0.3.4.8. Could be
 				// replaced with callback.transportDisabled() when fixed.
 				disableNetwork();
-				updateConnectionStatus(networkManager.getNetworkStatus());
+				updateConnectionStatus(networkManager.getNetworkStatus(),
+						batteryManager.isCharging());
 			}
 		} else if (e instanceof NetworkStatusEvent) {
-			updateConnectionStatus(((NetworkStatusEvent) e).getStatus());
+			updateConnectionStatus(((NetworkStatusEvent) e).getStatus(),
+					batteryManager.isCharging());
+		} else if (e instanceof BatteryEvent) {
+			updateConnectionStatus(networkManager.getNetworkStatus(),
+					((BatteryEvent) e).isCharging());
 		}
 	}
 
@@ -664,7 +695,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		});
 	}
 
-	private void updateConnectionStatus(NetworkStatus status) {
+	private void updateConnectionStatus(NetworkStatus status,
+			boolean charging) {
 		connectionStatusExecutor.execute(() -> {
 			if (!running) return;
 			boolean online = status.isConnected();
@@ -682,6 +714,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				LOG.info("Online: " + online + ", wifi: " + wifi);
 				if ("".equals(country)) LOG.info("Country code unknown");
 				else LOG.info("Country code: " + country);
+				LOG.info("Charging: " + charging);
 			}
 
 			try {
@@ -705,12 +738,24 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 					enableBridges(false);
 					enableNetwork(true);
 				}
+				if (online && wifi && charging) {
+					LOG.info("Enabling connection padding");
+					enableConnectionPadding(true);
+				} else {
+					LOG.info("Disabling connection padding");
+					enableConnectionPadding(false);
+				}
 			} catch (IOException e) {
 				logException(LOG, WARNING, e);
 			}
 		});
 	}
 
+	private void enableConnectionPadding(boolean enable) throws IOException {
+		if (!running) return;
+		controlConnection.setConf("ConnectionPadding", enable ? "1" : "0");
+	}
+
 	// TODO remove when sufficient time has passed. Added 2018-08-15
 	private void migrateSettings() {
 		Settings sOld = callback.getSettings();

bramble-core/src/main/java/org/briarproject/bramble/properties/PropertiesModule.java

@@ -5,7 +5,7 @@ import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.data.MetadataEncoder;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
-import org.briarproject.bramble.api.sync.ValidationManager;
+import org.briarproject.bramble.api.sync.validation.ValidationManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 

bramble-core/src/main/java/org/briarproject/bramble/properties/TransportPropertyManagerImpl.java

@@ -24,7 +24,7 @@ import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.InvalidMessageException;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.sync.ValidationManager.IncomingMessageHook;
+import org.briarproject.bramble.api.sync.validation.IncomingMessageHook;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager.ClientVersioningHook;
@@ -142,15 +142,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	@Override
 	public Map<TransportId, TransportProperties> getLocalProperties()
 			throws DbException {
-		Map<TransportId, TransportProperties> local;
-		Transaction txn = db.startTransaction(true);
-		try {
-			local = getLocalProperties(txn);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return local;
+		return db.transactionWithResult(true, this::getLocalProperties);
 	}
 
 	@Override
@@ -176,9 +168,8 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	public TransportProperties getLocalProperties(TransportId t)
 			throws DbException {
 		try {
-			TransportProperties p = null;
-			Transaction txn = db.startTransaction(true);
-			try {
+			return db.transactionWithResult(true, txn -> {
+				TransportProperties p = null;
 				// Find the latest local update
 				LatestUpdate latest = findLatest(txn, localGroup.getId(), t,
 						true);
@@ -188,11 +179,8 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 							latest.messageId);
 					p = parseProperties(message);
 				}
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
-			return p == null ? new TransportProperties() : p;
+				return p == null ? new TransportProperties() : p;
+			});
 		} catch (FormatException e) {
 			throw new DbException(e);
 		}
@@ -201,16 +189,12 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	@Override
 	public Map<ContactId, TransportProperties> getRemoteProperties(
 			TransportId t) throws DbException {
-		Map<ContactId, TransportProperties> remote = new HashMap<>();
-		Transaction txn = db.startTransaction(true);
-		try {
+		return db.transactionWithResult(true, txn -> {
+			Map<ContactId, TransportProperties> remote = new HashMap<>();
 			for (Contact c : db.getContacts(txn))
 				remote.put(c.getId(), getRemoteProperties(txn, c, t));
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return remote;
+			return remote;
+		});
 	}
 
 	private TransportProperties getRemoteProperties(Transaction txn, Contact c,
@@ -234,23 +218,15 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 	@Override
 	public TransportProperties getRemoteProperties(ContactId c, TransportId t)
 			throws DbException {
-		TransportProperties p;
-		Transaction txn = db.startTransaction(true);
-		try {
-			p = getRemoteProperties(txn, db.getContact(txn, c), t);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return p;
+		return db.transactionWithResult(true, txn ->
+				getRemoteProperties(txn, db.getContact(txn, c), t));
 	}
 
 	@Override
 	public void mergeLocalProperties(TransportId t, TransportProperties p)
 			throws DbException {
 		try {
-			Transaction txn = db.startTransaction(false);
-			try {
+			db.transaction(false, txn -> {
 				// Merge the new properties with any existing properties
 				TransportProperties merged;
 				boolean changed;
@@ -287,10 +263,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 							db.removeMessage(txn, latest.messageId);
 					}
 				}
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
+			});
 		} catch (FormatException e) {
 			throw new DbException(e);
 		}

bramble-core/src/main/java/org/briarproject/bramble/settings/SettingsManagerImpl.java

@@ -23,15 +23,8 @@ class SettingsManagerImpl implements SettingsManager {
 
 	@Override
 	public Settings getSettings(String namespace) throws DbException {
-		Settings s;
-		Transaction txn = db.startTransaction(true);
-		try {
-			s = db.getSettings(txn, namespace);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return s;
+		return db.transactionWithResult(true, txn ->
+				db.getSettings(txn, namespace));
 	}
 
 	@Override
@@ -42,12 +35,6 @@ class SettingsManagerImpl implements SettingsManager {
 
 	@Override
 	public void mergeSettings(Settings s, String namespace) throws DbException {
-		Transaction txn = db.startTransaction(false);
-		try {
-			db.mergeSettings(txn, s, namespace);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
+		db.transaction(false, txn -> db.mergeSettings(txn, s, namespace));
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/sync/DuplexOutgoingSession.java

@@ -5,7 +5,6 @@ import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
@@ -230,14 +229,8 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (interrupted) return;
 			if (!generateAckQueued.getAndSet(false)) throw new AssertionError();
 			try {
-				Ack a;
-				Transaction txn = db.startTransaction(false);
-				try {
-					a = db.generateAck(txn, contactId, MAX_MESSAGE_IDS);
-					db.commitTransaction(txn);
-				} finally {
-					db.endTransaction(txn);
-				}
+				Ack a = db.transactionWithNullableResult(false, txn ->
+						db.generateAck(txn, contactId, MAX_MESSAGE_IDS));
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated ack: " + (a != null));
 				if (a != null) writerTasks.add(new WriteAck(a));
@@ -275,16 +268,15 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (!generateBatchQueued.getAndSet(false))
 				throw new AssertionError();
 			try {
-				Collection<Message> b;
-				Transaction txn = db.startTransaction(false);
-				try {
-					b = db.generateRequestedBatch(txn, contactId,
-							MAX_RECORD_PAYLOAD_BYTES, maxLatency);
-					setNextSendTime(db.getNextSendTime(txn, contactId));
-					db.commitTransaction(txn);
-				} finally {
-					db.endTransaction(txn);
-				}
+				Collection<Message> b =
+						db.transactionWithNullableResult(false, txn -> {
+							Collection<Message> batch =
+									db.generateRequestedBatch(txn, contactId,
+											MAX_RECORD_PAYLOAD_BYTES,
+											maxLatency);
+							setNextSendTime(db.getNextSendTime(txn, contactId));
+							return batch;
+						});
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated batch: " + (b != null));
 				if (b != null) writerTasks.add(new WriteBatch(b));
@@ -322,16 +314,12 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (!generateOfferQueued.getAndSet(false))
 				throw new AssertionError();
 			try {
-				Offer o;
-				Transaction txn = db.startTransaction(false);
-				try {
-					o = db.generateOffer(txn, contactId, MAX_MESSAGE_IDS,
-							maxLatency);
+				Offer o = db.transactionWithNullableResult(false, txn -> {
+					Offer offer = db.generateOffer(txn, contactId,
+							MAX_MESSAGE_IDS, maxLatency);
 					setNextSendTime(db.getNextSendTime(txn, contactId));
-					db.commitTransaction(txn);
-				} finally {
-					db.endTransaction(txn);
-				}
+					return offer;
+				});
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated offer: " + (o != null));
 				if (o != null) writerTasks.add(new WriteOffer(o));
@@ -369,14 +357,8 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (!generateRequestQueued.getAndSet(false))
 				throw new AssertionError();
 			try {
-				Request r;
-				Transaction txn = db.startTransaction(false);
-				try {
-					r = db.generateRequest(txn, contactId, MAX_MESSAGE_IDS);
-					db.commitTransaction(txn);
-				} finally {
-					db.endTransaction(txn);
-				}
+				Request r = db.transactionWithNullableResult(false, txn ->
+						db.generateRequest(txn, contactId, MAX_MESSAGE_IDS));
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated request: " + (r != null));
 				if (r != null) writerTasks.add(new WriteRequest(r));

bramble-core/src/main/java/org/briarproject/bramble/sync/IncomingSession.java

@@ -6,7 +6,6 @@ import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
@@ -120,13 +119,8 @@ class IncomingSession implements SyncSession, EventListener {
 		@Override
 		public void run() {
 			try {
-				Transaction txn = db.startTransaction(false);
-				try {
-					db.receiveAck(txn, contactId, ack);
-					db.commitTransaction(txn);
-				} finally {
-					db.endTransaction(txn);
-				}
+				db.transaction(false, txn ->
+						db.receiveAck(txn, contactId, ack));
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				interrupt();
@@ -146,13 +140,8 @@ class IncomingSession implements SyncSession, EventListener {
 		@Override
 		public void run() {
 			try {
-				Transaction txn = db.startTransaction(false);
-				try {
-					db.receiveMessage(txn, contactId, message);
-					db.commitTransaction(txn);
-				} finally {
-					db.endTransaction(txn);
-				}
+				db.transaction(false, txn ->
+						db.receiveMessage(txn, contactId, message));
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				interrupt();
@@ -172,13 +161,8 @@ class IncomingSession implements SyncSession, EventListener {
 		@Override
 		public void run() {
 			try {
-				Transaction txn = db.startTransaction(false);
-				try {
-					db.receiveOffer(txn, contactId, offer);
-					db.commitTransaction(txn);
-				} finally {
-					db.endTransaction(txn);
-				}
+				db.transaction(false, txn ->
+						db.receiveOffer(txn, contactId, offer));
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				interrupt();
@@ -198,13 +182,8 @@ class IncomingSession implements SyncSession, EventListener {
 		@Override
 		public void run() {
 			try {
-				Transaction txn = db.startTransaction(false);
-				try {
-					db.receiveRequest(txn, contactId, request);
-					db.commitTransaction(txn);
-				} finally {
-					db.endTransaction(txn);
-				}
+				db.transaction(false, txn ->
+						db.receiveRequest(txn, contactId, request));
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 				interrupt();

bramble-core/src/main/java/org/briarproject/bramble/sync/SimplexOutgoingSession.java

@@ -5,7 +5,6 @@ import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
@@ -47,7 +46,8 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 	private static final Logger LOG =
 			Logger.getLogger(SimplexOutgoingSession.class.getName());
 
-	private static final ThrowingRunnable<IOException> CLOSE = () -> {};
+	private static final ThrowingRunnable<IOException> CLOSE = () -> {
+	};
 
 	private final DatabaseComponent db;
 	private final Executor dbExecutor;
@@ -128,14 +128,8 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 		public void run() {
 			if (interrupted) return;
 			try {
-				Ack a;
-				Transaction txn = db.startTransaction(false);
-				try {
-					a = db.generateAck(txn, contactId, MAX_MESSAGE_IDS);
-					db.commitTransaction(txn);
-				} finally {
-					db.endTransaction(txn);
-				}
+				Ack a = db.transactionWithNullableResult(false, txn ->
+						db.generateAck(txn, contactId, MAX_MESSAGE_IDS));
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated ack: " + (a != null));
 				if (a == null) decrementOutstandingQueries();
@@ -172,15 +166,10 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 		public void run() {
 			if (interrupted) return;
 			try {
-				Collection<Message> b;
-				Transaction txn = db.startTransaction(false);
-				try {
-					b = db.generateBatch(txn, contactId,
-							MAX_RECORD_PAYLOAD_BYTES, maxLatency);
-					db.commitTransaction(txn);
-				} finally {
-					db.endTransaction(txn);
-				}
+				Collection<Message> b =
+						db.transactionWithNullableResult(false, txn ->
+								db.generateBatch(txn, contactId,
+										MAX_RECORD_PAYLOAD_BYTES, maxLatency));
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated batch: " + (b != null));
 				if (b == null) decrementOutstandingQueries();

bramble-core/src/main/java/org/briarproject/bramble/sync/SyncModule.java

@@ -1,23 +1,11 @@
 package org.briarproject.bramble.sync;
 
-import org.briarproject.bramble.PoliteExecutor;
-import org.briarproject.bramble.api.crypto.CryptoComponent;
-import org.briarproject.bramble.api.crypto.CryptoExecutor;
-import org.briarproject.bramble.api.db.DatabaseComponent;
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.sync.GroupFactory;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.SyncRecordReaderFactory;
 import org.briarproject.bramble.api.sync.SyncRecordWriterFactory;
 import org.briarproject.bramble.api.sync.SyncSessionFactory;
-import org.briarproject.bramble.api.sync.ValidationManager;
-import org.briarproject.bramble.api.system.Clock;
 
-import java.util.concurrent.Executor;
-
-import javax.inject.Inject;
 import javax.inject.Singleton;
 
 import dagger.Module;
@@ -26,29 +14,14 @@ import dagger.Provides;
 @Module
 public class SyncModule {
 
-	public static class EagerSingletons {
-		@Inject
-		ValidationManager validationManager;
-	}
-
-	/**
-	 * The maximum number of validation tasks to delegate to the crypto
-	 * executor concurrently.
-	 * <p>
-	 * The number of available processors can change during the lifetime of the
-	 * JVM, so this is just a reasonable guess.
-	 */
-	private static final int MAX_CONCURRENT_VALIDATION_TASKS =
-			Math.max(1, Runtime.getRuntime().availableProcessors() - 1);
-
 	@Provides
-	GroupFactory provideGroupFactory(CryptoComponent crypto) {
-		return new GroupFactoryImpl(crypto);
+	GroupFactory provideGroupFactory(GroupFactoryImpl groupFactory) {
+		return groupFactory;
 	}
 
 	@Provides
-	MessageFactory provideMessageFactory(CryptoComponent crypto) {
-		return new MessageFactoryImpl(crypto);
+	MessageFactory provideMessageFactory(MessageFactoryImpl messageFactory) {
+		return messageFactory;
 	}
 
 	@Provides
@@ -65,30 +38,8 @@ public class SyncModule {
 
 	@Provides
 	@Singleton
-	SyncSessionFactory provideSyncSessionFactory(DatabaseComponent db,
-			@DatabaseExecutor Executor dbExecutor, EventBus eventBus,
-			Clock clock, SyncRecordReaderFactory recordReaderFactory,
-			SyncRecordWriterFactory recordWriterFactory) {
-		return new SyncSessionFactoryImpl(db, dbExecutor, eventBus, clock,
-				recordReaderFactory, recordWriterFactory);
-	}
-
-	@Provides
-	@Singleton
-	ValidationManager provideValidationManager(
-			LifecycleManager lifecycleManager, EventBus eventBus,
-			ValidationManagerImpl validationManager) {
-		lifecycleManager.registerService(validationManager);
-		eventBus.addListener(validationManager);
-		return validationManager;
-	}
-
-	@Provides
-	@Singleton
-	@ValidationExecutor
-	Executor provideValidationExecutor(
-			@CryptoExecutor Executor cryptoExecutor) {
-		return new PoliteExecutor("ValidationExecutor", cryptoExecutor,
-				MAX_CONCURRENT_VALIDATION_TASKS);
+	SyncSessionFactory provideSyncSessionFactory(
+			SyncSessionFactoryImpl syncSessionFactory) {
+		return syncSessionFactory;
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/sync/validation/ValidationExecutor.java

@@ -1,4 +1,4 @@
-package org.briarproject.bramble.sync;
+package org.briarproject.bramble.sync.validation;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.Target;

bramble-core/src/main/java/org/briarproject/bramble/sync/validation/ValidationManagerImpl.java

@@ -1,5 +1,6 @@
-package org.briarproject.bramble.sync;
+package org.briarproject.bramble.sync.validation;
 
+import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
@@ -17,8 +18,11 @@ import org.briarproject.bramble.api.sync.InvalidMessageException;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageContext;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.sync.ValidationManager;
 import org.briarproject.bramble.api.sync.event.MessageAddedEvent;
+import org.briarproject.bramble.api.sync.validation.IncomingMessageHook;
+import org.briarproject.bramble.api.sync.validation.MessageState;
+import org.briarproject.bramble.api.sync.validation.MessageValidator;
+import org.briarproject.bramble.api.sync.validation.ValidationManager;
 import org.briarproject.bramble.api.versioning.ClientMajorVersion;
 
 import java.util.Collection;
@@ -36,9 +40,9 @@ import javax.inject.Inject;
 
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.DELIVERED;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.INVALID;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.PENDING;
+import static org.briarproject.bramble.api.sync.validation.MessageState.DELIVERED;
+import static org.briarproject.bramble.api.sync.validation.MessageState.INVALID;
+import static org.briarproject.bramble.api.sync.validation.MessageState.PENDING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @ThreadSafe
@@ -97,14 +101,8 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	@DatabaseExecutor
 	private void validateOutstandingMessages() {
 		try {
-			Queue<MessageId> unvalidated = new LinkedList<>();
-			Transaction txn = db.startTransaction(true);
-			try {
-				unvalidated.addAll(db.getMessagesToValidate(txn));
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
+			Queue<MessageId> unvalidated = new LinkedList<>(
+					db.transactionWithResult(true, db::getMessagesToValidate));
 			validateNextMessageAsync(unvalidated);
 		} catch (DbException e) {
 			logException(LOG, WARNING, e);
@@ -119,18 +117,14 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	@DatabaseExecutor
 	private void validateNextMessage(Queue<MessageId> unvalidated) {
 		try {
-			Message m;
-			Group g;
-			Transaction txn = db.startTransaction(true);
-			try {
+			Pair<Message, Group> mg = db.transactionWithResult(true, txn -> {
 				MessageId id = unvalidated.poll();
-				m = db.getMessage(txn, id);
-				g = db.getGroup(txn, m.getGroupId());
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
-			validateMessageAsync(m, g);
+				if (id == null) throw new AssertionError();
+				Message m = db.getMessage(txn, id);
+				Group g = db.getGroup(txn, m.getGroupId());
+				return new Pair<>(m, g);
+			});
+			validateMessageAsync(mg.getFirst(), mg.getSecond());
 			validateNextMessageAsync(unvalidated);
 		} catch (NoSuchMessageException e) {
 			LOG.info("Message removed before validation");
@@ -150,14 +144,8 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	@DatabaseExecutor
 	private void deliverOutstandingMessages() {
 		try {
-			Queue<MessageId> pending = new LinkedList<>();
-			Transaction txn = db.startTransaction(true);
-			try {
-				pending.addAll(db.getPendingMessages(txn));
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
+			Queue<MessageId> pending = new LinkedList<>(
+					db.transactionWithResult(true, db::getPendingMessages));
 			deliverNextPendingMessageAsync(pending);
 		} catch (DbException e) {
 			logException(LOG, WARNING, e);
@@ -172,24 +160,24 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	@DatabaseExecutor
 	private void deliverNextPendingMessage(Queue<MessageId> pending) {
 		try {
-			boolean anyInvalid = false, allDelivered = true;
-			Queue<MessageId> toShare = null;
-			Queue<MessageId> invalidate = null;
-			Transaction txn = db.startTransaction(false);
-			try {
+			Queue<MessageId> toShare = new LinkedList<>();
+			Queue<MessageId> invalidate = new LinkedList<>();
+			db.transaction(false, txn -> {
+				boolean anyInvalid = false, allDelivered = true;
 				MessageId id = pending.poll();
+				if (id == null) throw new AssertionError();
 				// Check if message is still pending
 				if (db.getMessageState(txn, id) == PENDING) {
 					// Check if dependencies are valid and delivered
-					Map<MessageId, State> states =
+					Map<MessageId, MessageState> states =
 							db.getMessageDependencies(txn, id);
-					for (Entry<MessageId, State> e : states.entrySet()) {
+					for (Entry<MessageId, MessageState> e : states.entrySet()) {
 						if (e.getValue() == INVALID) anyInvalid = true;
 						if (e.getValue() != DELIVERED) allDelivered = false;
 					}
 					if (anyInvalid) {
 						invalidateMessage(txn, id);
-						invalidate = getDependentsToInvalidate(txn, id);
+						addDependentsToInvalidate(txn, id, invalidate);
 					} else if (allDelivered) {
 						Message m = db.getMessage(txn, id);
 						Group g = db.getGroup(txn, m.getGroupId());
@@ -200,22 +188,19 @@ class ValidationManagerImpl implements ValidationManager, Service,
 						DeliveryResult result =
 								deliverMessage(txn, m, c, majorVersion, meta);
 						if (result.valid) {
-							pending.addAll(getPendingDependents(txn, id));
+							addPendingDependents(txn, id, pending);
 							if (result.share) {
 								db.setMessageShared(txn, id);
-								toShare = new LinkedList<>(states.keySet());
+								toShare.addAll(states.keySet());
 							}
 						} else {
-							invalidate = getDependentsToInvalidate(txn, id);
+							addDependentsToInvalidate(txn, id, invalidate);
 						}
 					}
 				}
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
-			if (invalidate != null) invalidateNextMessageAsync(invalidate);
-			if (toShare != null) shareNextMessageAsync(toShare);
+			});
+			if (!invalidate.isEmpty()) invalidateNextMessageAsync(invalidate);
+			if (!toShare.isEmpty()) shareNextMessageAsync(toShare);
 			deliverNextPendingMessageAsync(pending);
 		} catch (NoSuchMessageException e) {
 			LOG.info("Message removed before delivery");
@@ -264,20 +249,19 @@ class ValidationManagerImpl implements ValidationManager, Service,
 			MessageContext context) {
 		try {
 			MessageId id = m.getId();
-			boolean anyInvalid = false, allDelivered = true;
-			Queue<MessageId> invalidate = null;
-			Queue<MessageId> pending = null;
-			Queue<MessageId> toShare = null;
-			Transaction txn = db.startTransaction(false);
-			try {
+			Queue<MessageId> invalidate = new LinkedList<>();
+			Queue<MessageId> pending = new LinkedList<>();
+			Queue<MessageId> toShare = new LinkedList<>();
+			db.transaction(false, txn -> {
+				boolean anyInvalid = false, allDelivered = true;
 				// Check if message has any dependencies
 				Collection<MessageId> dependencies = context.getDependencies();
 				if (!dependencies.isEmpty()) {
 					db.addMessageDependencies(txn, m, dependencies);
 					// Check if dependencies are valid and delivered
-					Map<MessageId, State> states =
+					Map<MessageId, MessageState> states =
 							db.getMessageDependencies(txn, id);
-					for (Entry<MessageId, State> e : states.entrySet()) {
+					for (Entry<MessageId, MessageState> e : states.entrySet()) {
 						if (e.getValue() == INVALID) anyInvalid = true;
 						if (e.getValue() != DELIVERED) allDelivered = false;
 					}
@@ -285,7 +269,7 @@ class ValidationManagerImpl implements ValidationManager, Service,
 				if (anyInvalid) {
 					if (db.getMessageState(txn, id) != INVALID) {
 						invalidateMessage(txn, id);
-						invalidate = getDependentsToInvalidate(txn, id);
+						addDependentsToInvalidate(txn, id, invalidate);
 					}
 				} else {
 					Metadata meta = context.getMetadata();
@@ -294,25 +278,22 @@ class ValidationManagerImpl implements ValidationManager, Service,
 						DeliveryResult result =
 								deliverMessage(txn, m, c, majorVersion, meta);
 						if (result.valid) {
-							pending = getPendingDependents(txn, id);
+							addPendingDependents(txn, id, pending);
 							if (result.share) {
 								db.setMessageShared(txn, id);
-								toShare = new LinkedList<>(dependencies);
+								toShare.addAll(dependencies);
 							}
 						} else {
-							invalidate = getDependentsToInvalidate(txn, id);
+							addDependentsToInvalidate(txn, id, invalidate);
 						}
 					} else {
 						db.setMessageState(txn, id, PENDING);
 					}
 				}
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
-			if (invalidate != null) invalidateNextMessageAsync(invalidate);
-			if (pending != null) deliverNextPendingMessageAsync(pending);
-			if (toShare != null) shareNextMessageAsync(toShare);
+			});
+			if (!invalidate.isEmpty()) invalidateNextMessageAsync(invalidate);
+			if (!pending.isEmpty()) deliverNextPendingMessageAsync(pending);
+			if (!toShare.isEmpty()) shareNextMessageAsync(toShare);
 		} catch (NoSuchMessageException e) {
 			LOG.info("Message removed during validation");
 		} catch (NoSuchGroupException e) {
@@ -342,14 +323,12 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	}
 
 	@DatabaseExecutor
-	private Queue<MessageId> getPendingDependents(Transaction txn, MessageId m)
-			throws DbException {
-		Queue<MessageId> pending = new LinkedList<>();
-		Map<MessageId, State> states = db.getMessageDependents(txn, m);
-		for (Entry<MessageId, State> e : states.entrySet()) {
+	private void addPendingDependents(Transaction txn, MessageId m,
+			Queue<MessageId> pending) throws DbException {
+		Map<MessageId, MessageState> states = db.getMessageDependents(txn, m);
+		for (Entry<MessageId, MessageState> e : states.entrySet()) {
 			if (e.getValue() == PENDING) pending.add(e.getKey());
 		}
-		return pending;
 	}
 
 	private void shareOutstandingMessagesAsync() {
@@ -359,14 +338,8 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	@DatabaseExecutor
 	private void shareOutstandingMessages() {
 		try {
-			Queue<MessageId> toShare = new LinkedList<>();
-			Transaction txn = db.startTransaction(true);
-			try {
-				toShare.addAll(db.getMessagesToShare(txn));
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
+			Queue<MessageId> toShare = new LinkedList<>(
+					db.transactionWithResult(true, db::getMessagesToShare));
 			shareNextMessageAsync(toShare);
 		} catch (DbException e) {
 			logException(LOG, WARNING, e);
@@ -387,15 +360,12 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	@DatabaseExecutor
 	private void shareNextMessage(Queue<MessageId> toShare) {
 		try {
-			Transaction txn = db.startTransaction(false);
-			try {
+			db.transaction(false, txn -> {
 				MessageId id = toShare.poll();
+				if (id == null) throw new AssertionError();
 				db.setMessageShared(txn, id);
 				toShare.addAll(db.getMessageDependencies(txn, id).keySet());
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
+			});
 			shareNextMessageAsync(toShare);
 		} catch (NoSuchMessageException e) {
 			LOG.info("Message removed before sharing");
@@ -416,17 +386,14 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	@DatabaseExecutor
 	private void invalidateNextMessage(Queue<MessageId> invalidate) {
 		try {
-			Transaction txn = db.startTransaction(false);
-			try {
+			db.transaction(false, txn -> {
 				MessageId id = invalidate.poll();
+				if (id == null) throw new AssertionError();
 				if (db.getMessageState(txn, id) != INVALID) {
 					invalidateMessage(txn, id);
-					invalidate.addAll(getDependentsToInvalidate(txn, id));
+					addDependentsToInvalidate(txn, id, invalidate);
 				}
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
+			});
 			invalidateNextMessageAsync(invalidate);
 		} catch (NoSuchMessageException e) {
 			LOG.info("Message removed before invalidation");
@@ -445,14 +412,12 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	}
 
 	@DatabaseExecutor
-	private Queue<MessageId> getDependentsToInvalidate(Transaction txn,
-			MessageId m) throws DbException {
-		Queue<MessageId> invalidate = new LinkedList<>();
-		Map<MessageId, State> states = db.getMessageDependents(txn, m);
-		for (Entry<MessageId, State> e : states.entrySet()) {
+	private void addDependentsToInvalidate(Transaction txn,
+			MessageId m, Queue<MessageId> invalidate) throws DbException {
+		Map<MessageId, MessageState> states = db.getMessageDependents(txn, m);
+		for (Entry<MessageId, MessageState> e : states.entrySet()) {
 			if (e.getValue() != INVALID) invalidate.add(e.getKey());
 		}
-		return invalidate;
 	}
 
 	@Override
@@ -472,14 +437,8 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	@DatabaseExecutor
 	private void loadGroupAndValidate(Message m) {
 		try {
-			Group g;
-			Transaction txn = db.startTransaction(true);
-			try {
-				g = db.getGroup(txn, m.getGroupId());
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
+			Group g = db.transactionWithResult(true, txn ->
+					db.getGroup(txn, m.getGroupId()));
 			validateMessageAsync(m, g);
 		} catch (NoSuchGroupException e) {
 			LOG.info("Group removed before validation");

bramble-core/src/main/java/org/briarproject/bramble/sync/validation/ValidationModule.java

@@ -0,0 +1,53 @@
+package org.briarproject.bramble.sync.validation;
+
+import org.briarproject.bramble.PoliteExecutor;
+import org.briarproject.bramble.api.crypto.CryptoExecutor;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.sync.validation.ValidationManager;
+
+import java.util.concurrent.Executor;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class ValidationModule {
+
+	public static class EagerSingletons {
+		@Inject
+		ValidationManager validationManager;
+	}
+
+	/**
+	 * The maximum number of validation tasks to delegate to the crypto
+	 * executor concurrently.
+	 * <p>
+	 * The number of available processors can change during the lifetime of the
+	 * JVM, so this is just a reasonable guess.
+	 */
+	private static final int MAX_CONCURRENT_VALIDATION_TASKS =
+			Math.max(1, Runtime.getRuntime().availableProcessors() - 1);
+
+	@Provides
+	@Singleton
+	ValidationManager provideValidationManager(
+			LifecycleManager lifecycleManager, EventBus eventBus,
+			ValidationManagerImpl validationManager) {
+		lifecycleManager.registerService(validationManager);
+		eventBus.addListener(validationManager);
+		return validationManager;
+	}
+
+	@Provides
+	@Singleton
+	@ValidationExecutor
+	Executor provideValidationExecutor(
+			@CryptoExecutor Executor cryptoExecutor) {
+		return new PoliteExecutor("ValidationExecutor", cryptoExecutor,
+				MAX_CONCURRENT_VALIDATION_TASKS);
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/transport/KeyManagerImpl.java

@@ -72,8 +72,7 @@ class KeyManagerImpl implements KeyManager, Service, EventListener {
 		for (DuplexPluginFactory f : pluginConfig.getDuplexFactories())
 			transports.put(f.getId(), f.getMaxLatency());
 		try {
-			Transaction txn = db.startTransaction(false);
-			try {
+			db.transaction(false, txn -> {
 				for (Contact c : db.getContacts(txn))
 					if (c.isActive()) activeContacts.put(c.getId(), true);
 				for (Entry<TransportId, Integer> e : transports.entrySet())
@@ -85,10 +84,7 @@ class KeyManagerImpl implements KeyManager, Service, EventListener {
 					managers.put(e.getKey(), m);
 					m.start(txn);
 				}
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
+			});
 		} catch (DbException e) {
 			throw new ServiceException(e);
 		}
@@ -141,15 +137,8 @@ class KeyManagerImpl implements KeyManager, Service, EventListener {
 			if (LOG.isLoggable(INFO)) LOG.info("No key manager for " + t);
 			return null;
 		}
-		StreamContext ctx;
-		Transaction txn = db.startTransaction(false);
-		try {
-			ctx = m.getStreamContext(txn, c);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return ctx;
+		return db.transactionWithNullableResult(false, txn ->
+				m.getStreamContext(txn, c));
 	}
 
 	@Override
@@ -160,15 +149,8 @@ class KeyManagerImpl implements KeyManager, Service, EventListener {
 			if (LOG.isLoggable(INFO)) LOG.info("No key manager for " + t);
 			return null;
 		}
-		StreamContext ctx;
-		Transaction txn = db.startTransaction(false);
-		try {
-			ctx = m.getStreamContext(txn, tag);
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
-		}
-		return ctx;
+		return db.transactionWithNullableResult(false, txn ->
+				m.getStreamContext(txn, tag));
 	}
 
 	@Override

bramble-core/src/main/java/org/briarproject/bramble/transport/TransportKeyManagerImpl.java

@@ -162,13 +162,7 @@ class TransportKeyManagerImpl implements TransportKeyManager {
 	private void rotateKeys() {
 		dbExecutor.execute(() -> {
 			try {
-				Transaction txn = db.startTransaction(false);
-				try {
-					rotateKeys(txn);
-					db.commitTransaction(txn);
-				} finally {
-					db.endTransaction(txn);
-				}
+				db.transaction(false, this::rotateKeys);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 			}

bramble-core/src/main/java/org/briarproject/bramble/versioning/ClientVersioningManagerImpl.java

@@ -23,7 +23,7 @@ import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.InvalidMessageException;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.sync.ValidationManager.IncomingMessageHook;
+import org.briarproject.bramble.api.sync.validation.IncomingMessageHook;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.versioning.ClientMajorVersion;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
@@ -123,16 +123,12 @@ class ClientVersioningManagerImpl implements ClientVersioningManager, Client,
 		List<ClientVersion> versions = new ArrayList<>(clients);
 		Collections.sort(versions);
 		try {
-			Transaction txn = db.startTransaction(false);
-			try {
+			db.transaction(false, txn -> {
 				if (updateClientVersions(txn, versions)) {
 					for (Contact c : db.getContacts(txn))
 						clientVersionsUpdated(txn, c, versions);
 				}
-				db.commitTransaction(txn);
-			} finally {
-				db.endTransaction(txn);
-			}
+			});
 		} catch (DbException e) {
 			throw new ServiceException(e);
 		}

bramble-core/src/main/java/org/briarproject/bramble/versioning/VersioningModule.java

@@ -4,7 +4,7 @@ import org.briarproject.bramble.api.client.ClientHelper;
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.data.MetadataEncoder;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.sync.ValidationManager;
+import org.briarproject.bramble.api.sync.validation.ValidationManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 

bramble-core/src/main/resources/bridges

@@ -1,8 +1,4 @@
-Bridge 131.252.210.150:8081 0E858AC201BF0F3FA3C462F64844CBFFC7297A42
-Bridge 67.205.189.122:8443 12D64D5D44E20169585E7378580C0D33A872AD98
-Bridge 45.32.148.146:8443 0CE016FB2462D8BF179AE71F7D702D09DEAC3F1D
-Bridge 148.251.90.59:7510 019F727CA6DCA6CA5C90B55E477B7D87981E75BC
-Bridge 45.55.1.74:8443 6F18FEFBB0CAECD5ABA755312FCCB34FC11A7AB8
-Bridge 85.229.131.78:444 50E433CCC5FEC11CC34CB4D92033561E065EA106
-Bridge 178.62.62.193:8443 391B1F9B6A28A1C5FAE1872283985F975E5DB029
-Bridge 45.76.29.92:8443 ECF1DD51A46FDEF2C50CED992EEEAE8DED18DA0C
+Bridge obfs4 78.46.188.239:37356 5A2D2F4158D0453E00C7C176978D3F41D69C45DB cert=3c0SwxpOisbohNxEc4tb875RVW8eOu1opRTVXJhafaKA/PNNtI7ElQIVOVZg1AdL5bxGCw iat-mode=0
+Bridge obfs4 52.15.78.72:9443 02069A3C5362476936B62BA6F5ACC41ABD573A9B cert=ijYG/OKc7kqu2YzKNFfeXN7/BG2BOgfEP2KyYEiGDQthnHbsOiTWHeIG0WJVW+BckzDgKw iat-mode=0
+Bridge obfs4 13.58.29.242:9443 0C58939A77DA6B6B29D4B5236A75865659607AE0 cert=OylWIEHb/ezpq1zWxW0sgKRn+9ARH2eOcQOZ8/Gew+4l+oKOhQ2jUX/Y+FSl61JorXZUWA iat-mode=0
+Bridge obfs4 45.33.37.112:9443 60A609BB4ABE8D46E634AE81ED29ADAB7776B399 cert=t5v19WmNv5Sc2YPNr8RQids365W7MY8zJwQVkOxBjUMFomMWARDzsbYpcWLLcw0J9Gm+BQ iat-mode=0

bramble-core/src/test/java/org/briarproject/bramble/client/ClientHelperImplTest.java

@@ -22,6 +22,7 @@ import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.test.BrambleTestCase;
+import org.briarproject.bramble.test.DbExpectations;
 import org.briarproject.bramble.util.StringUtils;
 import org.jmock.Expectations;
 import org.jmock.Mockery;
@@ -85,14 +86,11 @@ public class ClientHelperImplTest extends BrambleTestCase {
 		boolean shared = new Random().nextBoolean();
 		Transaction txn = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			oneOf(metadataEncoder).encode(dictionary);
 			will(returnValue(metadata));
 			oneOf(db).addLocalMessage(txn, message, metadata, shared);
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		clientHelper.addLocalMessage(message, dictionary, shared);
@@ -116,13 +114,10 @@ public class ClientHelperImplTest extends BrambleTestCase {
 		Transaction txn = new Transaction(null, true);
 
 		expectToList(true);
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getMessage(txn, messageId);
 			will(returnValue(message));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		clientHelper.getMessageAsList(messageId);
@@ -133,15 +128,12 @@ public class ClientHelperImplTest extends BrambleTestCase {
 	public void testGetGroupMetadataAsDictionary() throws Exception {
 		Transaction txn = new Transaction(null, true);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getGroupMetadata(txn, groupId);
 			will(returnValue(metadata));
 			oneOf(metadataParser).parse(metadata);
 			will(returnValue(dictionary));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		assertEquals(dictionary,
@@ -153,15 +145,12 @@ public class ClientHelperImplTest extends BrambleTestCase {
 	public void testGetMessageMetadataAsDictionary() throws Exception {
 		Transaction txn = new Transaction(null, true);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getMessageMetadata(txn, messageId);
 			will(returnValue(metadata));
 			oneOf(metadataParser).parse(metadata);
 			will(returnValue(dictionary));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		assertEquals(dictionary,
@@ -175,15 +164,12 @@ public class ClientHelperImplTest extends BrambleTestCase {
 		map.put(messageId, dictionary);
 		Transaction txn = new Transaction(null, true);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getMessageMetadata(txn, groupId);
 			will(returnValue(Collections.singletonMap(messageId, metadata)));
 			oneOf(metadataParser).parse(metadata);
 			will(returnValue(dictionary));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		assertEquals(map, clientHelper.getMessageMetadataAsDictionary(groupId));
@@ -200,17 +186,14 @@ public class ClientHelperImplTest extends BrambleTestCase {
 		queryMetadata.put("query", getRandomBytes(42));
 		Transaction txn = new Transaction(null, true);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(metadataEncoder).encode(query);
 			will(returnValue(queryMetadata));
 			oneOf(db).getMessageMetadata(txn, groupId, queryMetadata);
 			will(returnValue(Collections.singletonMap(messageId, metadata)));
 			oneOf(metadataParser).parse(metadata);
 			will(returnValue(dictionary));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		assertEquals(map,
@@ -222,14 +205,11 @@ public class ClientHelperImplTest extends BrambleTestCase {
 	public void testMergeGroupMetadata() throws Exception {
 		Transaction txn = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			oneOf(metadataEncoder).encode(dictionary);
 			will(returnValue(metadata));
 			oneOf(db).mergeGroupMetadata(txn, groupId, metadata);
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		clientHelper.mergeGroupMetadata(groupId, dictionary);
@@ -240,14 +220,11 @@ public class ClientHelperImplTest extends BrambleTestCase {
 	public void testMergeMessageMetadata() throws Exception {
 		Transaction txn = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			oneOf(metadataEncoder).encode(dictionary);
 			will(returnValue(metadata));
 			oneOf(db).mergeMessageMetadata(txn, messageId, metadata);
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		clientHelper.mergeMessageMetadata(messageId, dictionary);

bramble-core/src/test/java/org/briarproject/bramble/contact/ContactManagerImplTest.java

@@ -69,17 +69,14 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 		boolean alice = new Random().nextBoolean();
 		Transaction txn = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(false), withDbCallable(txn));
 			oneOf(db).addContact(txn, remote, local, verified, active);
 			will(returnValue(contactId));
 			oneOf(keyManager).addContact(txn, contactId, master, timestamp,
 					alice, active);
 			oneOf(db).getContact(txn, contactId);
 			will(returnValue(contact));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		assertEquals(contactId, contactManager.addContact(remote, local,
@@ -89,13 +86,10 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 	@Test
 	public void testGetContact() throws Exception {
 		Transaction txn = new Transaction(null, true);
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getContact(txn, contactId);
 			will(returnValue(contact));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		assertEquals(contact, contactManager.getContact(contactId));
@@ -105,13 +99,10 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 	public void testGetContactByAuthor() throws Exception {
 		Transaction txn = new Transaction(null, true);
 		Collection<Contact> contacts = Collections.singleton(contact);
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getContactsByAuthorId(txn, remote.getId());
 			will(returnValue(contacts));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		assertEquals(contact, contactManager.getContact(remote.getId(), local));
@@ -120,12 +111,10 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 	@Test(expected = NoSuchContactException.class)
 	public void testGetContactByUnknownAuthor() throws Exception {
 		Transaction txn = new Transaction(null, true);
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getContactsByAuthorId(txn, remote.getId());
 			will(returnValue(emptyList()));
-			oneOf(db).endTransaction(txn);
 		}});
 
 		contactManager.getContact(remote.getId(), local);
@@ -135,31 +124,26 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 	public void testGetContactByUnknownLocalAuthor() throws Exception {
 		Transaction txn = new Transaction(null, true);
 		Collection<Contact> contacts = Collections.singleton(contact);
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getContactsByAuthorId(txn, remote.getId());
 			will(returnValue(contacts));
-			oneOf(db).endTransaction(txn);
 		}});
 
 		contactManager.getContact(remote.getId(), new AuthorId(getRandomId()));
 	}
 
 	@Test
-	public void testActiveContacts() throws Exception {
+	public void testGetActiveContacts() throws Exception {
 		Collection<Contact> activeContacts = Collections.singletonList(contact);
 		Collection<Contact> contacts = new ArrayList<>(activeContacts);
 		contacts.add(new Contact(new ContactId(3), remote, local, alias, true,
 				false));
 		Transaction txn = new Transaction(null, true);
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getContacts(txn);
 			will(returnValue(contacts));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		assertEquals(activeContacts, contactManager.getActiveContacts());
@@ -168,14 +152,11 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 	@Test
 	public void testRemoveContact() throws Exception {
 		Transaction txn = new Transaction(null, false);
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			oneOf(db).getContact(txn, contactId);
 			will(returnValue(contact));
 			oneOf(db).removeContact(txn, contactId);
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		contactManager.removeContact(contactId);
@@ -195,7 +176,7 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 	public void testSetContactAlias() throws Exception {
 		Transaction txn = new Transaction(null, false);
 		context.checking(new DbExpectations() {{
-			oneOf(db).transaction(with(equal(false)), withDbRunnable(txn));
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			oneOf(db).setContactAlias(txn, contactId, alias);
 		}});
 
@@ -204,35 +185,32 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 
 	@Test(expected = IllegalArgumentException.class)
 	public void testSetContactAliasTooLong() throws Exception {
-		contactManager.setContactAlias(contactId,
+		Transaction txn = new Transaction(null, false);
+		contactManager.setContactAlias(txn, contactId,
 				getRandomString(MAX_AUTHOR_NAME_LENGTH + 1));
 	}
 
 	@Test
 	public void testContactExists() throws Exception {
 		Transaction txn = new Transaction(null, true);
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).containsContact(txn, remote.getId(), local);
 			will(returnValue(true));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		assertTrue(contactManager.contactExists(remote.getId(), local));
 	}
 
 	@Test
-	public void testGetAuthorStatus() throws Exception {
+	public void testGetAuthorInfo() throws Exception {
 		Transaction txn = new Transaction(null, true);
 		Collection<Contact> contacts = singletonList(
 				new Contact(new ContactId(1), remote, localAuthor.getId(),
 						alias, false, true));
 
 		context.checking(new DbExpectations() {{
-			oneOf(db).transactionWithResult(with(equal(true)),
-					withDbCallable(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(identityManager).getLocalAuthor(txn);
 			will(returnValue(localAuthor));
 			oneOf(db).getContactsByAuthorId(txn, remote.getId());
@@ -245,7 +223,7 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 	}
 
 	@Test
-	public void testGetAuthorStatusTransaction() throws DbException {
+	public void testGetAuthorInfoTransaction() throws DbException {
 		Transaction txn = new Transaction(null, true);
 
 		// check unknown author
@@ -264,7 +242,7 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 		Collection<Contact> contacts = singletonList(
 				new Contact(new ContactId(1), remote, localAuthor.getId(),
 						alias, false, true));
-		checkAuthorStatusContext(txn, remote.getId(), contacts);
+		checkAuthorInfoContext(txn, remote.getId(), contacts);
 		authorInfo = contactManager.getAuthorInfo(txn, remote.getId());
 		assertEquals(UNVERIFIED, authorInfo.getStatus());
 		assertEquals(alias, contact.getAlias());
@@ -272,7 +250,7 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 		// check verified contact
 		contacts = singletonList(new Contact(new ContactId(1), remote,
 				localAuthor.getId(), alias, true, true));
-		checkAuthorStatusContext(txn, remote.getId(), contacts);
+		checkAuthorInfoContext(txn, remote.getId(), contacts);
 		authorInfo = contactManager.getAuthorInfo(txn, remote.getId());
 		assertEquals(VERIFIED, authorInfo.getStatus());
 		assertEquals(alias, contact.getAlias());
@@ -288,7 +266,7 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 		assertNull(authorInfo.getAlias());
 	}
 
-	private void checkAuthorStatusContext(Transaction txn, AuthorId authorId,
+	private void checkAuthorInfoContext(Transaction txn, AuthorId authorId,
 			Collection<Contact> contacts) throws DbException {
 		context.checking(new Expectations() {{
 			oneOf(identityManager).getLocalAuthor(txn);

bramble-core/src/test/java/org/briarproject/bramble/data/BdfReaderImplFuzzingTest.java

@@ -0,0 +1,41 @@
+package org.briarproject.bramble.data;
+
+import org.briarproject.bramble.test.BrambleTestCase;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.util.Random;
+
+import static org.briarproject.bramble.api.data.BdfReader.DEFAULT_MAX_BUFFER_SIZE;
+import static org.briarproject.bramble.api.data.BdfReader.DEFAULT_NESTED_LIMIT;
+import static org.briarproject.bramble.test.TestUtils.isOptionalTestEnabled;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeTrue;
+
+public class BdfReaderImplFuzzingTest extends BrambleTestCase {
+
+	@Before
+	public void setUp() {
+		assumeTrue(isOptionalTestEnabled(BdfReaderImplFuzzingTest.class));
+	}
+
+	@Test
+	public void testStringFuzzing() throws Exception {
+		Random random = new Random();
+		byte[] buf = new byte[22];
+		ByteArrayInputStream in = new ByteArrayInputStream(buf);
+		for (int i = 0; i < 100_000_000; i++) {
+			random.nextBytes(buf);
+			buf[0] = 0x41; // String with 1-byte length
+			buf[1] = 0x14; // Length 20 bytes
+			in.reset();
+			BdfReaderImpl r = new BdfReaderImpl(in, DEFAULT_NESTED_LIMIT,
+					DEFAULT_MAX_BUFFER_SIZE);
+			int length = r.readString().length();
+			assertTrue(length >= 0);
+			assertTrue(length <= 20);
+			assertTrue(r.eof());
+		}
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/db/DatabasePerformanceTest.java

@@ -11,7 +11,7 @@ import org.briarproject.bramble.api.sync.Group;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.sync.ValidationManager.State;
+import org.briarproject.bramble.api.sync.validation.MessageState;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.test.UTest;
 import org.junit.After;
@@ -33,7 +33,7 @@ import java.util.logging.Logger;
 
 import static java.util.logging.Level.OFF;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_IDS;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.DELIVERED;
+import static org.briarproject.bramble.api.sync.validation.MessageState.DELIVERED;
 import static org.briarproject.bramble.test.TestUtils.deleteTestDirectory;
 import static org.briarproject.bramble.test.TestUtils.getAuthor;
 import static org.briarproject.bramble.test.TestUtils.getGroup;
@@ -565,7 +565,8 @@ public abstract class DatabasePerformanceTest extends BrambleTestCase {
 				for (int k = 0; k < MESSAGES_PER_GROUP; k++) {
 					Message m = getMessage(g.getId());
 					messages.add(m);
-					State state = State.fromValue(random.nextInt(4));
+					MessageState state =
+							MessageState.fromValue(random.nextInt(4));
 					boolean shared = random.nextBoolean();
 					ContactId sender = random.nextBoolean() ? c : null;
 					db.addMessage(txn, m, state, shared, sender);

bramble-core/src/test/java/org/briarproject/bramble/db/JdbcDatabaseTest.java

@@ -18,7 +18,7 @@ import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
-import org.briarproject.bramble.api.sync.ValidationManager.State;
+import org.briarproject.bramble.api.sync.validation.MessageState;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.transport.IncomingKeys;
 import org.briarproject.bramble.api.transport.KeySet;
@@ -58,10 +58,10 @@ import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
 import static org.briarproject.bramble.api.sync.Group.Visibility.VISIBLE;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.DELIVERED;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.INVALID;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.PENDING;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.UNKNOWN;
+import static org.briarproject.bramble.api.sync.validation.MessageState.DELIVERED;
+import static org.briarproject.bramble.api.sync.validation.MessageState.INVALID;
+import static org.briarproject.bramble.api.sync.validation.MessageState.PENDING;
+import static org.briarproject.bramble.api.sync.validation.MessageState.UNKNOWN;
 import static org.briarproject.bramble.db.DatabaseConstants.DB_SETTINGS_NAMESPACE;
 import static org.briarproject.bramble.db.DatabaseConstants.LAST_COMPACTED_KEY;
 import static org.briarproject.bramble.db.DatabaseConstants.MAX_COMPACTION_INTERVAL_MS;
@@ -1309,7 +1309,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		db.addMessageDependency(txn, message1, messageId3, PENDING);
 		db.addMessageDependency(txn, message2, messageId4, INVALID);
 
-		Map<MessageId, State> dependencies;
+		Map<MessageId, MessageState> dependencies;
 
 		// Retrieve dependencies for root
 		dependencies = db.getMessageDependencies(txn, messageId);
@@ -1333,7 +1333,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		dependencies = db.getMessageDependencies(txn, messageId4);
 		assertEquals(0, dependencies.size());
 
-		Map<MessageId, State> dependents;
+		Map<MessageId, MessageState> dependents;
 
 		// Root message does not have dependents
 		dependents = db.getMessageDependents(txn, messageId);
@@ -1408,7 +1408,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		db.addMessageDependency(txn, message, messageId3, PENDING);
 
 		// Retrieve the dependencies for the root
-		Map<MessageId, State> dependencies;
+		Map<MessageId, MessageState> dependencies;
 		dependencies = db.getMessageDependencies(txn, messageId);
 
 		// The cross-group dependency should have state UNKNOWN
@@ -1421,7 +1421,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(DELIVERED, dependencies.get(messageId3));
 
 		// Retrieve the dependents for the message in the second group
-		Map<MessageId, State> dependents;
+		Map<MessageId, MessageState> dependents;
 		dependents = db.getMessageDependents(txn, messageId1);
 
 		// The cross-group dependent should be excluded

bramble-core/src/test/java/org/briarproject/bramble/identity/IdentityManagerImplTest.java

@@ -11,6 +11,7 @@ import org.briarproject.bramble.api.identity.AuthorFactory;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.briarproject.bramble.test.DbExpectations;
 import org.jmock.Expectations;
 import org.junit.Before;
 import org.junit.Test;
@@ -64,13 +65,10 @@ public class IdentityManagerImplTest extends BrambleMockTestCase {
 	}
 
 	@Test
-	public void testRegisterAndStoreLocalAuthor() throws DbException {
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+	public void testRegisterAndStoreLocalAuthor() throws Exception {
+		context.checking(new DbExpectations() {{
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			oneOf(db).addLocalAuthor(txn, localAuthor);
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		identityManager.registerLocalAuthor(localAuthor);
@@ -79,14 +77,11 @@ public class IdentityManagerImplTest extends BrambleMockTestCase {
 	}
 
 	@Test
-	public void testGetLocalAuthor() throws DbException {
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+	public void testGetLocalAuthor() throws Exception {
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getLocalAuthors(txn);
 			will(returnValue(localAuthors));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 		assertEquals(localAuthor, identityManager.getLocalAuthor());
 	}

bramble-core/src/test/java/org/briarproject/bramble/properties/TransportPropertyManagerImplTest.java

@@ -21,16 +21,18 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.briarproject.bramble.test.DbExpectations;
 import org.jmock.Expectations;
 import org.junit.Test;
 
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
+import static java.util.Arrays.asList;
 import static java.util.Collections.singletonList;
+import static java.util.Collections.singletonMap;
 import static org.briarproject.bramble.api.properties.TransportPropertyManager.CLIENT_ID;
 import static org.briarproject.bramble.api.properties.TransportPropertyManager.MAJOR_VERSION;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
@@ -351,14 +353,11 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 				new BdfEntry("local", true)
 		));
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					localGroup.getId());
 			will(returnValue(messageMetadata));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		TransportPropertyManagerImpl t = createInstance();
@@ -386,9 +385,8 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		));
 		BdfList fooUpdate = BdfList.of("foo", 1, fooPropertiesDict);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					localGroup.getId());
 			will(returnValue(messageMetadata));
@@ -397,8 +395,6 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).parseAndValidateTransportProperties(
 					fooPropertiesDict);
 			will(returnValue(fooProperties));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		TransportPropertyManagerImpl t = createInstance();
@@ -413,8 +409,7 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		Contact contact1 = getContact(false);
 		Contact contact2 = getContact(true);
 		Contact contact3 = getContact(true);
-		List<Contact> contacts =
-				Arrays.asList(contact1, contact2, contact3);
+		List<Contact> contacts = asList(contact1, contact2, contact3);
 		Group contactGroup2 = getGroup(CLIENT_ID, MAJOR_VERSION);
 		Group contactGroup3 = getGroup(CLIENT_ID, MAJOR_VERSION);
 		Map<MessageId, BdfDictionary> messageMetadata3 =
@@ -442,9 +437,8 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		));
 		BdfList fooUpdate = BdfList.of("foo", 1, fooPropertiesDict);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getContacts(txn);
 			will(returnValue(contacts));
 			// First contact: skipped because not active
@@ -467,8 +461,6 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).parseAndValidateTransportProperties(
 					fooPropertiesDict);
 			will(returnValue(fooProperties));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		TransportPropertyManagerImpl t = createInstance();
@@ -485,17 +477,16 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			throws Exception {
 		Transaction txn = new Transaction(null, false);
 		MessageId updateId = new MessageId(getRandomId());
-		Map<MessageId, BdfDictionary> messageMetadata =
-				Collections.singletonMap(updateId, BdfDictionary.of(
+		Map<MessageId, BdfDictionary> messageMetadata = singletonMap(updateId,
+				BdfDictionary.of(
 						new BdfEntry("transportId", "foo"),
 						new BdfEntry("version", 1),
 						new BdfEntry("local", true)
 				));
 		BdfList update = BdfList.of("foo", 1, fooPropertiesDict);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			// Merge the new properties with the existing properties
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					localGroup.getId());
@@ -506,8 +497,6 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 					fooPropertiesDict);
 			will(returnValue(fooProperties));
 			// Properties are unchanged so we're done
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		TransportPropertyManagerImpl t = createInstance();
@@ -520,9 +509,8 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		Contact contact = getContact(true);
 		Group contactGroup = getGroup(CLIENT_ID, MAJOR_VERSION);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			// There are no existing properties to merge with
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					localGroup.getId());
@@ -541,8 +529,6 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			will(returnValue(Collections.emptyMap()));
 			expectStoreMessage(txn, contactGroup.getId(), "foo",
 					fooPropertiesDict, 1, true, true);
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		TransportPropertyManagerImpl t = createInstance();
@@ -561,10 +547,10 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		);
 		MessageId localGroupUpdateId = new MessageId(getRandomId());
 		Map<MessageId, BdfDictionary> localGroupMessageMetadata =
-				Collections.singletonMap(localGroupUpdateId, oldMetadata);
+				singletonMap(localGroupUpdateId, oldMetadata);
 		MessageId contactGroupUpdateId = new MessageId(getRandomId());
 		Map<MessageId, BdfDictionary> contactGroupMessageMetadata =
-				Collections.singletonMap(contactGroupUpdateId, oldMetadata);
+				singletonMap(contactGroupUpdateId, oldMetadata);
 		TransportProperties oldProperties = new TransportProperties();
 		oldProperties.put("fooKey1", "oldFooValue1");
 		BdfDictionary oldPropertiesDict = BdfDictionary.of(
@@ -572,9 +558,8 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		);
 		BdfList oldUpdate = BdfList.of("foo", 1, oldPropertiesDict);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			// Merge the new properties with the existing properties
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					localGroup.getId());
@@ -602,8 +587,6 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 					fooPropertiesDict, 2, true, true);
 			// Delete the previous update
 			oneOf(db).removeMessage(txn, contactGroupUpdateId);
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		TransportPropertyManagerImpl t = createInstance();

bramble-core/src/test/java/org/briarproject/bramble/sync/SimplexOutgoingSessionTest.java

@@ -11,8 +11,8 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.SyncRecordWriter;
 import org.briarproject.bramble.api.transport.StreamWriter;
 import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.briarproject.bramble.test.DbExpectations;
 import org.briarproject.bramble.test.ImmediateExecutor;
-import org.jmock.Expectations;
 import org.junit.Test;
 
 import java.util.concurrent.Executor;
@@ -45,24 +45,20 @@ public class SimplexOutgoingSessionTest extends BrambleMockTestCase {
 		Transaction noAckTxn = new Transaction(null, false);
 		Transaction noMsgTxn = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Add listener
 			oneOf(eventBus).addListener(session);
 			// No acks to send
-			oneOf(db).startTransaction(false);
-			will(returnValue(noAckTxn));
+			oneOf(db).transactionWithNullableResult(with(false),
+					withNullableDbCallable(noAckTxn));
 			oneOf(db).generateAck(noAckTxn, contactId, MAX_MESSAGE_IDS);
 			will(returnValue(null));
-			oneOf(db).commitTransaction(noAckTxn);
-			oneOf(db).endTransaction(noAckTxn);
 			// No messages to send
-			oneOf(db).startTransaction(false);
-			will(returnValue(noMsgTxn));
+			oneOf(db).transactionWithNullableResult(with(false),
+					withNullableDbCallable(noMsgTxn));
 			oneOf(db).generateBatch(with(noMsgTxn), with(contactId),
 					with(any(int.class)), with(MAX_LATENCY));
 			will(returnValue(null));
-			oneOf(db).commitTransaction(noMsgTxn);
-			oneOf(db).endTransaction(noMsgTxn);
 			// Send the end of stream marker
 			oneOf(streamWriter).sendEndOfStream();
 			// Remove listener
@@ -83,41 +79,33 @@ public class SimplexOutgoingSessionTest extends BrambleMockTestCase {
 		Transaction msgTxn = new Transaction(null, false);
 		Transaction noMsgTxn = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Add listener
 			oneOf(eventBus).addListener(session);
 			// One ack to send
-			oneOf(db).startTransaction(false);
-			will(returnValue(ackTxn));
+			oneOf(db).transactionWithNullableResult(with(false),
+					withNullableDbCallable(ackTxn));
 			oneOf(db).generateAck(ackTxn, contactId, MAX_MESSAGE_IDS);
 			will(returnValue(ack));
-			oneOf(db).commitTransaction(ackTxn);
-			oneOf(db).endTransaction(ackTxn);
 			oneOf(recordWriter).writeAck(ack);
 			// One message to send
-			oneOf(db).startTransaction(false);
-			will(returnValue(msgTxn));
+			oneOf(db).transactionWithNullableResult(with(false),
+					withNullableDbCallable(msgTxn));
 			oneOf(db).generateBatch(with(msgTxn), with(contactId),
 					with(any(int.class)), with(MAX_LATENCY));
 			will(returnValue(singletonList(message)));
-			oneOf(db).commitTransaction(msgTxn);
-			oneOf(db).endTransaction(msgTxn);
 			oneOf(recordWriter).writeMessage(message);
 			// No more acks
-			oneOf(db).startTransaction(false);
-			will(returnValue(noAckTxn));
+			oneOf(db).transactionWithNullableResult(with(false),
+					withNullableDbCallable(noAckTxn));
 			oneOf(db).generateAck(noAckTxn, contactId, MAX_MESSAGE_IDS);
 			will(returnValue(null));
-			oneOf(db).commitTransaction(noAckTxn);
-			oneOf(db).endTransaction(noAckTxn);
 			// No more messages
-			oneOf(db).startTransaction(false);
-			will(returnValue(noMsgTxn));
+			oneOf(db).transactionWithNullableResult(with(false),
+					withNullableDbCallable(noMsgTxn));
 			oneOf(db).generateBatch(with(noMsgTxn), with(contactId),
 					with(any(int.class)), with(MAX_LATENCY));
 			will(returnValue(null));
-			oneOf(db).commitTransaction(noMsgTxn);
-			oneOf(db).endTransaction(noMsgTxn);
 			// Send the end of stream marker
 			oneOf(streamWriter).sendEndOfStream();
 			// Remove listener

bramble-core/src/test/java/org/briarproject/bramble/sync/SyncIntegrationTestComponent.java

@@ -2,6 +2,7 @@ package org.briarproject.bramble.sync;
 
 import org.briarproject.bramble.crypto.CryptoModule;
 import org.briarproject.bramble.record.RecordModule;
+import org.briarproject.bramble.sync.validation.ValidationModule;
 import org.briarproject.bramble.system.SystemModule;
 import org.briarproject.bramble.test.TestSecureRandomModule;
 import org.briarproject.bramble.transport.TransportModule;
@@ -17,6 +18,7 @@ import dagger.Component;
 		RecordModule.class,
 		SyncModule.class,
 		SystemModule.class,
+		ValidationModule.class,
 		TransportModule.class
 })
 interface SyncIntegrationTestComponent {

bramble-core/src/test/java/org/briarproject/bramble/sync/validation/ValidationManagerImplTest.java

@@ -1,4 +1,4 @@
-package org.briarproject.bramble.sync;
+package org.briarproject.bramble.sync.validation;
 
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.db.DatabaseComponent;
@@ -13,29 +13,29 @@ import org.briarproject.bramble.api.sync.InvalidMessageException;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageContext;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.sync.ValidationManager.IncomingMessageHook;
-import org.briarproject.bramble.api.sync.ValidationManager.MessageValidator;
-import org.briarproject.bramble.api.sync.ValidationManager.State;
 import org.briarproject.bramble.api.sync.event.MessageAddedEvent;
+import org.briarproject.bramble.api.sync.validation.IncomingMessageHook;
+import org.briarproject.bramble.api.sync.validation.MessageState;
+import org.briarproject.bramble.api.sync.validation.MessageValidator;
 import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.briarproject.bramble.test.DbExpectations;
 import org.briarproject.bramble.test.ImmediateExecutor;
-import org.jmock.Expectations;
 import org.junit.Before;
 import org.junit.Test;
 
-import java.util.Arrays;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.concurrent.Executor;
 
+import static java.util.Arrays.asList;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.emptyMap;
 import static java.util.Collections.singletonList;
 import static java.util.Collections.singletonMap;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.DELIVERED;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.INVALID;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.PENDING;
-import static org.briarproject.bramble.api.sync.ValidationManager.State.UNKNOWN;
+import static org.briarproject.bramble.api.sync.validation.MessageState.DELIVERED;
+import static org.briarproject.bramble.api.sync.validation.MessageState.INVALID;
+import static org.briarproject.bramble.api.sync.validation.MessageState.PENDING;
+import static org.briarproject.bramble.api.sync.validation.MessageState.UNKNOWN;
 import static org.briarproject.bramble.test.TestUtils.getClientId;
 import static org.briarproject.bramble.test.TestUtils.getGroup;
 import static org.briarproject.bramble.test.TestUtils.getMessage;
@@ -83,28 +83,19 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn1 = new Transaction(null, true);
 		Transaction txn2 = new Transaction(null, true);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// validateOutstandingMessages()
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getMessagesToValidate(txn);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 			// deliverOutstandingMessages()
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn1));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
 			oneOf(db).getPendingMessages(txn1);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 			// shareOutstandingMessages()
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn2));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn2));
 			oneOf(db).getMessagesToShare(txn2);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn2);
-			oneOf(db).endTransaction(txn2);
 		}});
 
 		vm.startService();
@@ -121,29 +112,22 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn5 = new Transaction(null, true);
 		Transaction txn6 = new Transaction(null, true);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Get messages to validate
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getMessagesToValidate(txn);
-			will(returnValue(Arrays.asList(messageId, messageId1)));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
+			will(returnValue(asList(messageId, messageId1)));
 			// Load the first raw message and group
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn1));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
 			oneOf(db).getMessage(txn1, messageId);
 			will(returnValue(message));
 			oneOf(db).getGroup(txn1, groupId);
 			will(returnValue(group));
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 			// Validate the first message: valid
 			oneOf(validator).validateMessage(message, group);
 			will(returnValue(validResult));
 			// Store the validation result for the first message
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn2));
+			oneOf(db).transaction(with(false), withDbRunnable(txn2));
 			oneOf(db).mergeMessageMetadata(txn2, messageId, metadata);
 			// Deliver the first message
 			oneOf(hook).incomingMessage(txn2, message, metadata);
@@ -152,23 +136,17 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get any pending dependents
 			oneOf(db).getMessageDependents(txn2, messageId);
 			will(returnValue(emptyMap()));
-			oneOf(db).commitTransaction(txn2);
-			oneOf(db).endTransaction(txn2);
 			// Load the second raw message and group
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn3));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn3));
 			oneOf(db).getMessage(txn3, messageId1);
 			will(returnValue(message1));
 			oneOf(db).getGroup(txn3, groupId);
 			will(returnValue(group));
-			oneOf(db).commitTransaction(txn3);
-			oneOf(db).endTransaction(txn3);
 			// Validate the second message: invalid
 			oneOf(validator).validateMessage(message1, group);
 			will(throwException(new InvalidMessageException()));
 			// Store the validation result for the second message
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn4));
+			oneOf(db).transaction(with(false), withDbRunnable(txn4));
 			oneOf(db).getMessageState(txn4, messageId1);
 			will(returnValue(UNKNOWN));
 			oneOf(db).setMessageState(txn4, messageId1, INVALID);
@@ -177,22 +155,14 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Recursively invalidate any dependents
 			oneOf(db).getMessageDependents(txn4, messageId1);
 			will(returnValue(emptyMap()));
-			oneOf(db).commitTransaction(txn4);
-			oneOf(db).endTransaction(txn4);
 			// Get pending messages to deliver
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn5));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn5));
 			oneOf(db).getPendingMessages(txn5);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn5);
-			oneOf(db).endTransaction(txn5);
 			// Get messages to share
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn6));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn6));
 			oneOf(db).getMessagesToShare(txn6);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn6);
-			oneOf(db).endTransaction(txn6);
 		}});
 
 		vm.startService();
@@ -206,24 +176,17 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn3 = new Transaction(null, false);
 		Transaction txn4 = new Transaction(null, true);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Get messages to validate
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getMessagesToValidate(txn);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 			// Get pending messages to deliver
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn1));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
 			oneOf(db).getPendingMessages(txn1);
 			will(returnValue(singletonList(messageId)));
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 			// Check whether the message is ready to deliver
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn2));
+			oneOf(db).transaction(with(false), withDbRunnable(txn2));
 			oneOf(db).getMessageState(txn2, messageId);
 			will(returnValue(PENDING));
 			oneOf(db).getMessageDependencies(txn2, messageId);
@@ -242,11 +205,8 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get any pending dependents
 			oneOf(db).getMessageDependents(txn2, messageId);
 			will(returnValue(singletonMap(messageId2, PENDING)));
-			oneOf(db).commitTransaction(txn2);
-			oneOf(db).endTransaction(txn2);
 			// Check whether the dependent is ready to deliver
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn3));
+			oneOf(db).transaction(with(false), withDbRunnable(txn3));
 			oneOf(db).getMessageState(txn3, messageId2);
 			will(returnValue(PENDING));
 			oneOf(db).getMessageDependencies(txn3, messageId2);
@@ -265,16 +225,11 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get any pending dependents
 			oneOf(db).getMessageDependents(txn3, messageId2);
 			will(returnValue(emptyMap()));
-			oneOf(db).commitTransaction(txn3);
-			oneOf(db).endTransaction(txn3);
 
 			// Get messages to share
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn4));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn4));
 			oneOf(db).getMessagesToShare(txn4);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn4);
-			oneOf(db).endTransaction(txn4);
 		}});
 
 		vm.startService();
@@ -288,45 +243,30 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn3 = new Transaction(null, false);
 		Transaction txn4 = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// No messages to validate
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getMessagesToValidate(txn);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 			// No pending messages to deliver
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn1));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
 			oneOf(db).getPendingMessages(txn1);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 
 			// Get messages to share
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn2));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn2));
 			oneOf(db).getMessagesToShare(txn2);
 			will(returnValue(singletonList(messageId)));
-			oneOf(db).commitTransaction(txn2);
-			oneOf(db).endTransaction(txn2);
 			// Share message and get dependencies
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn3));
+			oneOf(db).transaction(with(false), withDbRunnable(txn3));
 			oneOf(db).setMessageShared(txn3, messageId);
 			oneOf(db).getMessageDependencies(txn3, messageId);
 			will(returnValue(singletonMap(messageId2, DELIVERED)));
-			oneOf(db).commitTransaction(txn3);
-			oneOf(db).endTransaction(txn3);
 			// Share dependency
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn4));
+			oneOf(db).transaction(with(false), withDbRunnable(txn4));
 			oneOf(db).setMessageShared(txn4, messageId2);
 			oneOf(db).getMessageDependencies(txn4, messageId2);
 			will(returnValue(emptyMap()));
-			oneOf(db).commitTransaction(txn4);
-			oneOf(db).endTransaction(txn4);
 		}});
 
 		vm.startService();
@@ -338,20 +278,16 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn1 = new Transaction(null, false);
 		Transaction txn2 = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Load the group
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getGroup(txn, groupId);
 			will(returnValue(group));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 			// Validate the message: valid
 			oneOf(validator).validateMessage(message, group);
 			will(returnValue(validResultWithDependencies));
 			// Store the validation result
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn1));
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
 			oneOf(db).addMessageDependencies(txn1, message,
 					validResultWithDependencies.getDependencies());
 			oneOf(db).getMessageDependencies(txn1, messageId);
@@ -366,16 +302,11 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			will(returnValue(emptyMap()));
 			// Share message
 			oneOf(db).setMessageShared(txn1, messageId);
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 			// Share dependencies
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn2));
+			oneOf(db).transaction(with(false), withDbRunnable(txn2));
 			oneOf(db).setMessageShared(txn2, messageId1);
 			oneOf(db).getMessageDependencies(txn2, messageId1);
 			will(returnValue(emptyMap()));
-			oneOf(db).commitTransaction(txn2);
-			oneOf(db).endTransaction(txn2);
 		}});
 
 		vm.eventOccurred(new MessageAddedEvent(message, contactId));
@@ -391,36 +322,26 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn4 = new Transaction(null, true);
 		Transaction txn5 = new Transaction(null, true);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Get messages to validate
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getMessagesToValidate(txn);
-			will(returnValue(Arrays.asList(messageId, messageId1)));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
+			will(returnValue(asList(messageId, messageId1)));
 			// Load the first raw message - *gasp* it's gone!
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn1));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
 			oneOf(db).getMessage(txn1, messageId);
 			will(throwException(new NoSuchMessageException()));
-			never(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 			// Load the second raw message and group
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn2));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn2));
 			oneOf(db).getMessage(txn2, messageId1);
 			will(returnValue(message1));
 			oneOf(db).getGroup(txn2, groupId);
 			will(returnValue(group));
-			oneOf(db).commitTransaction(txn2);
-			oneOf(db).endTransaction(txn2);
 			// Validate the second message: invalid
 			oneOf(validator).validateMessage(message1, group);
 			will(throwException(new InvalidMessageException()));
 			// Invalidate the second message
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn3));
+			oneOf(db).transaction(with(false), withDbRunnable(txn3));
 			oneOf(db).getMessageState(txn3, messageId1);
 			will(returnValue(UNKNOWN));
 			oneOf(db).setMessageState(txn3, messageId1, INVALID);
@@ -429,22 +350,14 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Recursively invalidate dependents
 			oneOf(db).getMessageDependents(txn3, messageId1);
 			will(returnValue(emptyMap()));
-			oneOf(db).commitTransaction(txn3);
-			oneOf(db).endTransaction(txn3);
 			// Get pending messages to deliver
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn4));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn4));
 			oneOf(db).getPendingMessages(txn4);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn4);
-			oneOf(db).endTransaction(txn4);
 			// Get messages to share
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn5));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn5));
 			oneOf(db).getMessagesToShare(txn5);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn5);
-			oneOf(db).endTransaction(txn5);
 		}});
 
 		vm.startService();
@@ -460,39 +373,29 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn4 = new Transaction(null, true);
 		Transaction txn5 = new Transaction(null, true);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Get messages to validate
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getMessagesToValidate(txn);
-			will(returnValue(Arrays.asList(messageId, messageId1)));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
+			will(returnValue(asList(messageId, messageId1)));
 			// Load the first raw message
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn1));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
 			oneOf(db).getMessage(txn1, messageId);
 			will(returnValue(message));
 			// Load the group - *gasp* it's gone!
 			oneOf(db).getGroup(txn1, groupId);
 			will(throwException(new NoSuchGroupException()));
-			never(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 			// Load the second raw message and group
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn2));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn2));
 			oneOf(db).getMessage(txn2, messageId1);
 			will(returnValue(message1));
 			oneOf(db).getGroup(txn2, groupId);
 			will(returnValue(group));
-			oneOf(db).commitTransaction(txn2);
-			oneOf(db).endTransaction(txn2);
 			// Validate the second message: invalid
 			oneOf(validator).validateMessage(message1, group);
 			will(throwException(new InvalidMessageException()));
 			// Store the validation result for the second message
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn3));
+			oneOf(db).transaction(with(false), withDbRunnable(txn3));
 			oneOf(db).getMessageState(txn3, messageId1);
 			will(returnValue(UNKNOWN));
 			oneOf(db).setMessageState(txn3, messageId1, INVALID);
@@ -501,22 +404,14 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Recursively invalidate dependents
 			oneOf(db).getMessageDependents(txn3, messageId1);
 			will(returnValue(emptyMap()));
-			oneOf(db).commitTransaction(txn3);
-			oneOf(db).endTransaction(txn3);
 			// Get pending messages to deliver
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn4));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn4));
 			oneOf(db).getPendingMessages(txn4);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn4);
-			oneOf(db).endTransaction(txn4);
 			// Get messages to share
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn5));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn5));
 			oneOf(db).getMessagesToShare(txn5);
 			will(returnValue(emptyList()));
-			oneOf(db).commitTransaction(txn5);
-			oneOf(db).endTransaction(txn5);
 		}});
 
 		vm.startService();
@@ -527,20 +422,16 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn = new Transaction(null, true);
 		Transaction txn1 = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Load the group
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getGroup(txn, groupId);
 			will(returnValue(group));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 			// Validate the message: valid
 			oneOf(validator).validateMessage(message, group);
 			will(returnValue(validResult));
 			// Store the validation result
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn1));
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
 			oneOf(db).mergeMessageMetadata(txn1, messageId, metadata);
 			// Deliver the message
 			oneOf(hook).incomingMessage(txn1, message, metadata);
@@ -549,8 +440,6 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get any pending dependents
 			oneOf(db).getMessageDependents(txn1, messageId);
 			will(returnValue(emptyMap()));
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 		}});
 
 		vm.eventOccurred(new MessageAddedEvent(message, contactId));
@@ -567,28 +456,22 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn = new Transaction(null, true);
 		Transaction txn1 = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Load the group
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getGroup(txn, groupId);
 			will(returnValue(group));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 			// Validate the message: valid
 			oneOf(validator).validateMessage(message, group);
 			will(returnValue(validResultWithDependencies));
 			// Store the validation result
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn1));
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
 			oneOf(db).addMessageDependencies(txn1, message,
 					validResultWithDependencies.getDependencies());
 			oneOf(db).getMessageDependencies(txn1, messageId);
 			will(returnValue(singletonMap(messageId1, UNKNOWN)));
 			oneOf(db).mergeMessageMetadata(txn1, messageId, metadata);
 			oneOf(db).setMessageState(txn1, messageId, PENDING);
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 		}});
 
 		vm.eventOccurred(new MessageAddedEvent(message, contactId));
@@ -600,20 +483,16 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn = new Transaction(null, true);
 		Transaction txn1 = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Load the group
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getGroup(txn, groupId);
 			will(returnValue(group));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 			// Validate the message: valid
 			oneOf(validator).validateMessage(message, group);
 			will(returnValue(validResultWithDependencies));
 			// Store the validation result
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn1));
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
 			oneOf(db).addMessageDependencies(txn1, message,
 					validResultWithDependencies.getDependencies());
 			oneOf(db).getMessageDependencies(txn1, messageId);
@@ -626,8 +505,6 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get any pending dependents
 			oneOf(db).getMessageDependents(txn1, messageId);
 			will(returnValue(emptyMap()));
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 		}});
 
 		vm.eventOccurred(new MessageAddedEvent(message, contactId));
@@ -640,20 +517,16 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn1 = new Transaction(null, false);
 		Transaction txn2 = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Load the group
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getGroup(txn, groupId);
 			will(returnValue(group));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 			// Validate the message: valid
 			oneOf(validator).validateMessage(message, group);
 			will(returnValue(validResultWithDependencies));
 			// Store the validation result
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn1));
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
 			oneOf(db).addMessageDependencies(txn1, message,
 					validResultWithDependencies.getDependencies());
 			// Check for invalid dependencies
@@ -668,11 +541,8 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Recursively invalidate dependents
 			oneOf(db).getMessageDependents(txn1, messageId);
 			will(returnValue(singletonMap(messageId2, UNKNOWN)));
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 			// Invalidate dependent in a new transaction
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn2));
+			oneOf(db).transaction(with(false), withDbRunnable(txn2));
 			oneOf(db).getMessageState(txn2, messageId2);
 			will(returnValue(UNKNOWN));
 			oneOf(db).setMessageState(txn2, messageId2, INVALID);
@@ -680,8 +550,6 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			oneOf(db).deleteMessageMetadata(txn2, messageId2);
 			oneOf(db).getMessageDependents(txn2, messageId2);
 			will(returnValue(emptyMap()));
-			oneOf(db).commitTransaction(txn2);
-			oneOf(db).endTransaction(txn2);
 		}});
 
 		vm.eventOccurred(new MessageAddedEvent(message, contactId));
@@ -691,7 +559,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 	public void testRecursiveInvalidation() throws Exception {
 		MessageId messageId3 = new MessageId(getRandomId());
 		MessageId messageId4 = new MessageId(getRandomId());
-		Map<MessageId, State> twoDependents = new LinkedHashMap<>();
+		Map<MessageId, MessageState> twoDependents = new LinkedHashMap<>();
 		twoDependents.put(messageId1, PENDING);
 		twoDependents.put(messageId2, PENDING);
 		Transaction txn = new Transaction(null, true);
@@ -702,20 +570,16 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn5 = new Transaction(null, false);
 		Transaction txn6 = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Load the group
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getGroup(txn, groupId);
 			will(returnValue(group));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 			// Validate the message: invalid
 			oneOf(validator).validateMessage(message, group);
 			will(throwException(new InvalidMessageException()));
 			// Invalidate the message
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn1));
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
 			oneOf(db).getMessageState(txn1, messageId);
 			will(returnValue(UNKNOWN));
 			oneOf(db).setMessageState(txn1, messageId, INVALID);
@@ -724,11 +588,8 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// The message has two dependents: 1 and 2
 			oneOf(db).getMessageDependents(txn1, messageId);
 			will(returnValue(twoDependents));
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 			// Invalidate message 1
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn2));
+			oneOf(db).transaction(with(false), withDbRunnable(txn2));
 			oneOf(db).getMessageState(txn2, messageId1);
 			will(returnValue(PENDING));
 			oneOf(db).setMessageState(txn2, messageId1, INVALID);
@@ -737,11 +598,8 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Message 1 has one dependent: 3
 			oneOf(db).getMessageDependents(txn2, messageId1);
 			will(returnValue(singletonMap(messageId3, PENDING)));
-			oneOf(db).commitTransaction(txn2);
-			oneOf(db).endTransaction(txn2);
 			// Invalidate message 2
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn3));
+			oneOf(db).transaction(with(false), withDbRunnable(txn3));
 			oneOf(db).getMessageState(txn3, messageId2);
 			will(returnValue(PENDING));
 			oneOf(db).setMessageState(txn3, messageId2, INVALID);
@@ -750,11 +608,8 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Message 2 has one dependent: 3 (same dependent as 1)
 			oneOf(db).getMessageDependents(txn3, messageId2);
 			will(returnValue(singletonMap(messageId3, PENDING)));
-			oneOf(db).commitTransaction(txn3);
-			oneOf(db).endTransaction(txn3);
 			// Invalidate message 3 (via 1)
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn4));
+			oneOf(db).transaction(with(false), withDbRunnable(txn4));
 			oneOf(db).getMessageState(txn4, messageId3);
 			will(returnValue(PENDING));
 			oneOf(db).setMessageState(txn4, messageId3, INVALID);
@@ -763,18 +618,12 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Message 3 has one dependent: 4
 			oneOf(db).getMessageDependents(txn4, messageId3);
 			will(returnValue(singletonMap(messageId4, PENDING)));
-			oneOf(db).commitTransaction(txn4);
-			oneOf(db).endTransaction(txn4);
 			// Invalidate message 3 (again, via 2)
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn5));
+			oneOf(db).transaction(with(false), withDbRunnable(txn5));
 			oneOf(db).getMessageState(txn5, messageId3);
 			will(returnValue(INVALID)); // Already invalidated
-			oneOf(db).commitTransaction(txn5);
-			oneOf(db).endTransaction(txn5);
 			// Invalidate message 4 (via 1 and 3)
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn6));
+			oneOf(db).transaction(with(false), withDbRunnable(txn6));
 			oneOf(db).getMessageState(txn6, messageId4);
 			will(returnValue(PENDING));
 			oneOf(db).setMessageState(txn6, messageId4, INVALID);
@@ -783,8 +632,6 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Message 4 has no dependents
 			oneOf(db).getMessageDependents(txn6, messageId4);
 			will(returnValue(emptyMap()));
-			oneOf(db).commitTransaction(txn6);
-			oneOf(db).endTransaction(txn6);
 		}});
 
 		vm.eventOccurred(new MessageAddedEvent(message, contactId));
@@ -796,10 +643,10 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Message message4 = getMessage(groupId);
 		MessageId messageId3 = message3.getId();
 		MessageId messageId4 = message4.getId();
-		Map<MessageId, State> twoDependents = new LinkedHashMap<>();
+		Map<MessageId, MessageState> twoDependents = new LinkedHashMap<>();
 		twoDependents.put(messageId1, PENDING);
 		twoDependents.put(messageId2, PENDING);
-		Map<MessageId, State> twoDependencies = new LinkedHashMap<>();
+		Map<MessageId, MessageState> twoDependencies = new LinkedHashMap<>();
 		twoDependencies.put(messageId1, DELIVERED);
 		twoDependencies.put(messageId2, DELIVERED);
 		Transaction txn = new Transaction(null, true);
@@ -810,20 +657,16 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 		Transaction txn5 = new Transaction(null, false);
 		Transaction txn6 = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Load the group
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getGroup(txn, groupId);
 			will(returnValue(group));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 			// Validate the message: valid
 			oneOf(validator).validateMessage(message, group);
 			will(returnValue(validResult));
 			// Store the validation result
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn1));
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
 			oneOf(db).mergeMessageMetadata(txn1, messageId, metadata);
 			// Deliver the message
 			oneOf(hook).incomingMessage(txn1, message, metadata);
@@ -832,11 +675,8 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// The message has two pending dependents: 1 and 2
 			oneOf(db).getMessageDependents(txn1, messageId);
 			will(returnValue(twoDependents));
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 			// Check whether message 1 is ready to be delivered
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn2));
+			oneOf(db).transaction(with(false), withDbRunnable(txn2));
 			oneOf(db).getMessageState(txn2, messageId1);
 			will(returnValue(PENDING));
 			oneOf(db).getMessageDependencies(txn2, messageId1);
@@ -855,11 +695,8 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Message 1 has one pending dependent: 3
 			oneOf(db).getMessageDependents(txn2, messageId1);
 			will(returnValue(singletonMap(messageId3, PENDING)));
-			oneOf(db).commitTransaction(txn2);
-			oneOf(db).endTransaction(txn2);
 			// Check whether message 2 is ready to be delivered
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn3));
+			oneOf(db).transaction(with(false), withDbRunnable(txn3));
 			oneOf(db).getMessageState(txn3, messageId2);
 			will(returnValue(PENDING));
 			oneOf(db).getMessageDependencies(txn3, messageId2);
@@ -878,11 +715,8 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Message 2 has one pending dependent: 3 (same dependent as 1)
 			oneOf(db).getMessageDependents(txn3, messageId2);
 			will(returnValue(singletonMap(messageId3, PENDING)));
-			oneOf(db).commitTransaction(txn3);
-			oneOf(db).endTransaction(txn3);
 			// Check whether message 3 is ready to be delivered (via 1)
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn4));
+			oneOf(db).transaction(with(false), withDbRunnable(txn4));
 			oneOf(db).getMessageState(txn4, messageId3);
 			will(returnValue(PENDING));
 			oneOf(db).getMessageDependencies(txn4, messageId3);
@@ -900,18 +734,12 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Message 3 has one pending dependent: 4
 			oneOf(db).getMessageDependents(txn4, messageId3);
 			will(returnValue(singletonMap(messageId4, PENDING)));
-			oneOf(db).commitTransaction(txn4);
-			oneOf(db).endTransaction(txn4);
 			// Check whether message 3 is ready to be delivered (again, via 2)
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn5));
+			oneOf(db).transaction(with(false), withDbRunnable(txn5));
 			oneOf(db).getMessageState(txn5, messageId3);
 			will(returnValue(DELIVERED)); // Already delivered
-			oneOf(db).commitTransaction(txn5);
-			oneOf(db).endTransaction(txn5);
 			// Check whether message 4 is ready to be delivered (via 1 and 3)
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn6));
+			oneOf(db).transaction(with(false), withDbRunnable(txn6));
 			oneOf(db).getMessageState(txn6, messageId4);
 			will(returnValue(PENDING));
 			oneOf(db).getMessageDependencies(txn6, messageId4);
@@ -930,8 +758,6 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Message 4 has no pending dependents
 			oneOf(db).getMessageDependents(txn6, messageId4);
 			will(returnValue(emptyMap()));
-			oneOf(db).commitTransaction(txn6);
-			oneOf(db).endTransaction(txn6);
 		}});
 
 		vm.eventOccurred(new MessageAddedEvent(message, contactId));
@@ -939,27 +765,23 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 
 	@Test
 	public void testOnlyReadyPendingDependentsGetDelivered() throws Exception {
-		Map<MessageId, State> twoDependencies = new LinkedHashMap<>();
+		Map<MessageId, MessageState> twoDependencies = new LinkedHashMap<>();
 		twoDependencies.put(messageId, DELIVERED);
 		twoDependencies.put(messageId2, UNKNOWN);
 		Transaction txn = new Transaction(null, true);
 		Transaction txn1 = new Transaction(null, false);
 		Transaction txn2 = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Load the group
-			oneOf(db).startTransaction(true);
-			will(returnValue(txn));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
 			oneOf(db).getGroup(txn, groupId);
 			will(returnValue(group));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 			// Validate the message: valid
 			oneOf(validator).validateMessage(message, group);
 			will(returnValue(validResult));
 			// Store the validation result
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn1));
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
 			oneOf(db).mergeMessageMetadata(txn1, messageId, metadata);
 			// Deliver the message
 			oneOf(hook).incomingMessage(txn1, message, metadata);
@@ -968,17 +790,12 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get any pending dependents
 			oneOf(db).getMessageDependents(txn1, messageId);
 			will(returnValue(singletonMap(messageId1, PENDING)));
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 			// Check whether the pending dependent is ready to be delivered
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn2));
+			oneOf(db).transaction(with(false), withDbRunnable(txn2));
 			oneOf(db).getMessageState(txn2, messageId1);
 			will(returnValue(PENDING));
 			oneOf(db).getMessageDependencies(txn2, messageId1);
 			will(returnValue(twoDependencies));
-			oneOf(db).commitTransaction(txn2);
-			oneOf(db).endTransaction(txn2);
 		}});
 
 		vm.eventOccurred(new MessageAddedEvent(message, contactId));

bramble-core/src/test/java/org/briarproject/bramble/test/DbExpectations.java

@@ -2,6 +2,7 @@ package org.briarproject.bramble.test;
 
 import org.briarproject.bramble.api.db.DbCallable;
 import org.briarproject.bramble.api.db.DbRunnable;
+import org.briarproject.bramble.api.db.NullableDbCallable;
 import org.briarproject.bramble.api.db.Transaction;
 import org.jmock.Expectations;
 
@@ -21,4 +22,12 @@ public class DbExpectations extends Expectations {
 		return null;
 	}
 
+	protected <R, E extends Exception> NullableDbCallable<R, E> withNullableDbCallable(
+			Transaction txn) {
+		addParameterMatcher(any(NullableDbCallable.class));
+		currentBuilder().setAction(
+				new RunTransactionWithNullableResultAction(txn));
+		return null;
+	}
+
 }

bramble-core/src/test/java/org/briarproject/bramble/test/RunTransactionWithNullableResultAction.java

@@ -0,0 +1,28 @@
+package org.briarproject.bramble.test;
+
+import org.briarproject.bramble.api.db.NullableDbCallable;
+import org.briarproject.bramble.api.db.Transaction;
+import org.hamcrest.Description;
+import org.jmock.api.Action;
+import org.jmock.api.Invocation;
+
+public class RunTransactionWithNullableResultAction implements Action {
+
+	private final Transaction txn;
+
+	public RunTransactionWithNullableResultAction(Transaction txn) {
+		this.txn = txn;
+	}
+
+	@Override
+	public Object invoke(Invocation invocation) throws Throwable {
+		NullableDbCallable task =
+				(NullableDbCallable) invocation.getParameter(1);
+		return task.call(txn);
+	}
+
+	@Override
+	public void describeTo(Description description) {
+		description.appendText("runs a task inside a database transaction");
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/transport/KeyManagerImplTest.java

@@ -15,6 +15,7 @@ import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.StreamContext;
 import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.briarproject.bramble.test.DbExpectations;
 import org.jmock.Expectations;
 import org.jmock.lib.concurrent.DeterministicExecutor;
 import org.junit.Before;
@@ -35,6 +36,7 @@ import static org.briarproject.bramble.test.TestUtils.getSecretKey;
 import static org.briarproject.bramble.test.TestUtils.getTransportId;
 import static org.briarproject.bramble.util.StringUtils.getRandomString;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
 
 public class KeyManagerImplTest extends BrambleMockTestCase {
 
@@ -77,7 +79,7 @@ public class KeyManagerImplTest extends BrambleMockTestCase {
 				singletonList(pluginFactory);
 		int maxLatency = 1337;
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			oneOf(pluginConfig).getSimplexFactories();
 			will(returnValue(factories));
 			oneOf(pluginFactory).getId();
@@ -89,13 +91,10 @@ public class KeyManagerImplTest extends BrambleMockTestCase {
 					.createTransportKeyManager(transportId, maxLatency);
 			will(returnValue(transportKeyManager));
 			oneOf(pluginConfig).getDuplexFactories();
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			oneOf(db).getContacts(txn);
 			will(returnValue(contacts));
 			oneOf(transportKeyManager).start(txn);
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		keyManager.startService();
@@ -121,25 +120,21 @@ public class KeyManagerImplTest extends BrambleMockTestCase {
 
 	@Test
 	public void testGetStreamContextForInactiveContact() throws Exception {
-		assertEquals(null,
-				keyManager.getStreamContext(inactiveContactId, transportId));
+		assertNull(keyManager.getStreamContext(inactiveContactId, transportId));
 	}
 
 	@Test
 	public void testGetStreamContextForUnknownTransport() throws Exception {
-		assertEquals(null,
-				keyManager.getStreamContext(contactId, unknownTransportId));
+		assertNull(keyManager.getStreamContext(contactId, unknownTransportId));
 	}
 
 	@Test
 	public void testGetStreamContextForContact() throws Exception {
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithNullableResult(with(false),
+					withNullableDbCallable(txn));
 			oneOf(transportKeyManager).getStreamContext(txn, contactId);
 			will(returnValue(streamContext));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		assertEquals(streamContext,
@@ -149,19 +144,16 @@ public class KeyManagerImplTest extends BrambleMockTestCase {
 	@Test
 	public void testGetStreamContextForTagAndUnknownTransport()
 			throws Exception {
-		assertEquals(null,
-				keyManager.getStreamContext(unknownTransportId, tag));
+		assertNull(keyManager.getStreamContext(unknownTransportId, tag));
 	}
 
 	@Test
 	public void testGetStreamContextForTag() throws Exception {
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithNullableResult(with(false),
+					withNullableDbCallable(txn));
 			oneOf(transportKeyManager).getStreamContext(txn, tag);
 			will(returnValue(streamContext));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		assertEquals(streamContext,
@@ -178,7 +170,7 @@ public class KeyManagerImplTest extends BrambleMockTestCase {
 
 		keyManager.eventOccurred(event);
 		executor.runUntilIdle();
-		assertEquals(null, keyManager.getStreamContext(contactId, transportId));
+		assertNull(keyManager.getStreamContext(contactId, transportId));
 	}
 
 	@Test
@@ -186,13 +178,11 @@ public class KeyManagerImplTest extends BrambleMockTestCase {
 		ContactStatusChangedEvent event =
 				new ContactStatusChangedEvent(inactiveContactId, true);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithNullableResult(with(false),
+					withNullableDbCallable(txn));
 			oneOf(transportKeyManager).getStreamContext(txn, inactiveContactId);
 			will(returnValue(streamContext));
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		keyManager.eventOccurred(event);

bramble-core/src/test/java/org/briarproject/bramble/transport/TransportKeyManagerImplTest.java

@@ -14,6 +14,7 @@ import org.briarproject.bramble.api.transport.OutgoingKeys;
 import org.briarproject.bramble.api.transport.StreamContext;
 import org.briarproject.bramble.api.transport.TransportKeys;
 import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.briarproject.bramble.test.DbExpectations;
 import org.briarproject.bramble.test.RunAction;
 import org.briarproject.bramble.test.TestUtils;
 import org.hamcrest.Description;
@@ -318,7 +319,7 @@ public class TransportKeyManagerImplTest extends BrambleMockTestCase {
 		Transaction txn = new Transaction(null, false);
 		Transaction txn1 = new Transaction(null, false);
 
-		context.checking(new Expectations() {{
+		context.checking(new DbExpectations() {{
 			// Get the current time (the start of rotation period 1000)
 			oneOf(clock).currentTimeMillis();
 			will(returnValue(rotationPeriodLength * 1000));
@@ -342,8 +343,7 @@ public class TransportKeyManagerImplTest extends BrambleMockTestCase {
 			oneOf(dbExecutor).execute(with(any(Runnable.class)));
 			will(new RunAction());
 			// Start a transaction for key rotation
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn1));
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
 			// Get the current time (the start of rotation period 1001)
 			oneOf(clock).currentTimeMillis();
 			will(returnValue(rotationPeriodLength * 1001));
@@ -364,9 +364,6 @@ public class TransportKeyManagerImplTest extends BrambleMockTestCase {
 			// Schedule key rotation at the start of the next rotation period
 			oneOf(scheduler).schedule(with(any(Runnable.class)),
 					with(rotationPeriodLength), with(MILLISECONDS));
-			// Commit the key rotation transaction
-			oneOf(db).commitTransaction(txn1);
-			oneOf(db).endTransaction(txn1);
 		}});
 
 		TransportKeyManager transportKeyManager = new TransportKeyManagerImpl(
@@ -539,7 +536,7 @@ public class TransportKeyManagerImplTest extends BrambleMockTestCase {
 		}
 
 		@Override
-		public Object invoke(Invocation invocation) throws Throwable {
+		public Object invoke(Invocation invocation) {
 			byte[] tag = (byte[]) invocation.getParameter(0);
 			random.nextBytes(tag);
 			if (tags != null) tags.add(tag);

bramble-core/src/test/java/org/briarproject/bramble/versioning/ClientVersioningManagerImplTest.java

@@ -18,6 +18,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager.ClientVersioningHook;
 import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.briarproject.bramble.test.DbExpectations;
 import org.jmock.Expectations;
 import org.junit.Test;
 
@@ -63,7 +64,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 	private final long now = System.currentTimeMillis();
 	private final Transaction txn = new Transaction(null, false);
 
-	private ClientVersioningManagerImpl createInstance() throws Exception {
+	private ClientVersioningManagerImpl createInstance() {
 		context.checking(new Expectations() {{
 			oneOf(contactGroupFactory).createLocalGroup(CLIENT_ID,
 					MAJOR_VERSION);
@@ -162,9 +163,8 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 		BdfList localUpdateBody = BdfList.of(BdfList.of(
 				BdfList.of(clientId.getString(), 123, 234, false)), 1L);
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			// No client versions have been stored yet
 			oneOf(db).getMessageIds(txn, localGroup.getId());
 			will(returnValue(emptyList()));
@@ -190,8 +190,6 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getMessageAsList(txn, localUpdateId);
 			will(returnValue(localUpdateBody));
 			// Latest local update is up-to-date, no visibilities have changed
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		ClientVersioningManagerImpl c = createInstance();
@@ -206,17 +204,14 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 		BdfList localVersionsBody =
 				BdfList.of(BdfList.of(clientId.getString(), 123, 234));
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			// Load the old client versions
 			oneOf(db).getMessageIds(txn, localGroup.getId());
 			will(returnValue(singletonList(localVersionsId)));
 			oneOf(clientHelper).getMessageAsList(txn, localVersionsId);
 			will(returnValue(localVersionsBody));
 			// Client versions are up-to-date
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		ClientVersioningManagerImpl c = createInstance();
@@ -251,9 +246,8 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 				new BdfEntry(MSG_KEY_UPDATE_VERSION, 2L),
 				new BdfEntry(MSG_KEY_LOCAL, true));
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			// Load the old client versions
 			oneOf(db).getMessageIds(txn, localGroup.getId());
 			will(returnValue(singletonList(oldLocalVersionsId)));
@@ -295,8 +289,6 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).addLocalMessage(txn, newLocalUpdate,
 					newLocalUpdateMeta, true);
 			// No visibilities have changed
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		ClientVersioningManagerImpl c = createInstance();
@@ -350,9 +342,8 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 				new BdfEntry(MSG_KEY_UPDATE_VERSION, 2L),
 				new BdfEntry(MSG_KEY_LOCAL, true));
 
-		context.checking(new Expectations() {{
-			oneOf(db).startTransaction(false);
-			will(returnValue(txn));
+		context.checking(new DbExpectations() {{
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			// Load the old client versions
 			oneOf(db).getMessageIds(txn, localGroup.getId());
 			will(returnValue(singletonList(oldLocalVersionsId)));
@@ -397,8 +388,6 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					newLocalUpdateMeta, true);
 			// The client's visibility has changed
 			oneOf(hook).onClientVisibilityChanging(txn, contact, visibility);
-			oneOf(db).commitTransaction(txn);
-			oneOf(db).endTransaction(txn);
 		}});
 
 		ClientVersioningManagerImpl c = createInstance();

bramble-core/witness.gradle

@@ -1,12 +1,20 @@
 dependencyVerification {
     verify = [
         'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
-        'com.google.dagger:dagger-compiler:2.0.2:dagger-compiler-2.0.2.jar:b74bc9de063dd4c6400b232231f2ef5056145b8fbecbf5382012007dd1c071b3',
-        'com.google.dagger:dagger-producers:2.0-beta:dagger-producers-2.0-beta.jar:99ec15e8a0507ba569e7655bc1165ee5e5ca5aa914b3c8f7e2c2458f724edd6b',
-        'com.google.dagger:dagger:2.0.2:dagger-2.0.2.jar:84c0282ed8be73a29e0475d639da030b55dee72369e58dd35ae7d4fe6243dcf9',
-        'com.google.guava:guava:18.0:guava-18.0.jar:d664fbfc03d2e5ce9cab2a44fb01f1d0bf9dfebeccc1a473b1f9ea31f79f6f99',
+        'com.google.code.findbugs:jsr305:1.3.9:jsr305-1.3.9.jar:905721a0eea90a81534abb7ee6ef4ea2e5e645fa1def0a5cd88402df1b46c9ed',
+        'com.google.dagger:dagger-compiler:2.19:dagger-compiler-2.19.jar:27a4b202a2de908182edb261f8c0a264e08e5e4733d7514bc7fbf0d31da5c0fc',
+        'com.google.dagger:dagger-producers:2.19:dagger-producers-2.19.jar:a17663abe0fc38b676026950907d4c5f5e2bf338375415861eaff6e3bdb0b768',
+        'com.google.dagger:dagger-spi:2.19:dagger-spi-2.19.jar:e7a6379d82c841f6aac2866948ad1eed716528707814602842a8d844ce04e2e1',
+        'com.google.dagger:dagger:2.19:dagger-2.19.jar:514b6f1e0727c6572e1d65cb27e4ae668b7aeaeb93a29515182965265b609939',
+        'com.google.errorprone:error_prone_annotations:2.1.3:error_prone_annotations-2.1.3.jar:03d0329547c13da9e17c634d1049ea2ead093925e290567e1a364fd6b1fc7ff8',
+        'com.google.errorprone:javac-shaded:9-dev-r4023-3:javac-shaded-9-dev-r4023-3.jar:65bfccf60986c47fbc17c9ebab0be626afc41741e0a6ec7109e0768817a36f30',
+        'com.google.googlejavaformat:google-java-format:1.5:google-java-format-1.5.jar:aa19ad7850fb85178aa22f2fddb163b84d6ce4d0035872f30d4408195ca1144e',
+        'com.google.guava:guava:25.0-jre:guava-25.0-jre.jar:3fd4341776428c7e0e5c18a7c10de129475b69ab9d30aeafbb5c277bb6074fa9',
+        'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:40ceb7157feb263949e0f503fe5f71689333a621021aa20ce0d0acee3badaa0f',
         'com.h2database:h2:1.4.192:h2-1.4.192.jar:225b22e9857235c46c93861410b60b8c81c10dc8985f4faf188985ba5445126c',
         'com.madgag.spongycastle:core:1.58.0.0:core-1.58.0.0.jar:199617dd5698c5a9312b898c0a4cec7ce9dd8649d07f65d91629f58229d72728',
+        'com.squareup:javapoet:1.11.1:javapoet-1.11.1.jar:9cbf2107be499ec6e95afd36b58e3ca122a24166cdd375732e51267d64058e90',
+        'javax.annotation:jsr250-api:1.0:jsr250-api-1.0.jar:a1a922d0d9b6d183ed3800dfac01d1e1eb159f0e8c6f94736931c1def54a941f',
         'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
         'junit:junit:4.12:junit-4.12.jar:59721f0805e223d84b90677887d9ff567dc534d7c502ca903c0c2b17f05c116a',
         'net.i2p.crypto:eddsa:0.2.0:eddsa-0.2.0.jar:a7cb1b85c16e2f0730b9204106929a1d9aaae1df728adc7041a8b8b605692140',
@@ -15,7 +23,9 @@ dependencyVerification {
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.bitlet:weupnp:0.1.4:weupnp-0.1.4.jar:88df7e6504929d00bdb832863761385c68ab92af945b04f0770b126270a444fb',
         'org.briarproject:jtorctl:0.3:jtorctl-0.3.jar:f2939238a097898998432effe93b0334d97a787972ab3a91a8973a1d309fc864',
+        'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.codehaus.mojo.signature:java16:1.1:java16-1.1.signature:53799223a2c98dba2d0add810bed76315460df285c69e4f397ae6098f87dd619',
+        'org.codehaus.mojo:animal-sniffer-annotations:1.14:animal-sniffer-annotations-1.14.jar:2068320bd6bad744c3673ab048f67e30bef8f518996fa380033556600669905d',
         'org.codehaus.mojo:animal-sniffer-ant-tasks:1.16:animal-sniffer-ant-tasks-1.16.jar:890040976fbe2d584619a6a61b1fd2e925b3b5eb342a85eb2762c467c0d64e90',
         'org.codehaus.mojo:animal-sniffer:1.16:animal-sniffer-1.16.jar:72be8bcc226ba43b937c722a08a07852bfa1b11400089265d5df0ee7b38b1d52',
         'org.hamcrest:hamcrest-core:1.3:hamcrest-core-1.3.jar:66fdef91e9739348df7a096aa384a5685f4e875584cce89386a7a47251c4d8e9',

bramble-java/build.gradle

@@ -2,10 +2,10 @@ apply plugin: 'java-library'
 sourceCompatibility = 1.8
 targetCompatibility = 1.8
 
-apply plugin: 'net.ltgt.apt'
 apply plugin: 'idea'
 apply plugin: 'witness'
 apply from: 'witness.gradle'
+apply from: '../dagger.gradle'
 
 configurations {
 	tor
@@ -17,8 +17,9 @@ dependencies {
 	implementation 'net.java.dev.jna:jna:4.5.2'
 	implementation 'net.java.dev.jna:jna-platform:4.5.2'
 	tor 'org.briarproject:tor:0.3.4.8@zip'
+	tor 'org.briarproject:obfs4proxy:0.0.7@zip'
 
-	apt 'com.google.dagger:dagger-compiler:2.0.2'
+	annotationProcessor 'com.google.dagger:dagger-compiler:2.19'
 
 	testImplementation project(path: ':bramble-api', configuration: 'testOutput')
 	testImplementation project(path: ':bramble-core', configuration: 'testOutput')
@@ -26,19 +27,35 @@ dependencies {
 	testImplementation "org.jmock:jmock:2.8.2"
 	testImplementation "org.jmock:jmock-junit4:2.8.2"
 	testImplementation "org.jmock:jmock-legacy:2.8.2"
-	testImplementation "org.hamcrest:hamcrest-library:1.3"
-	testImplementation "org.hamcrest:hamcrest-core:1.3"
 
-	testApt 'com.google.dagger:dagger-compiler:2.0.2'
+	testAnnotationProcessor 'com.google.dagger:dagger-compiler:2.19'
 }
 
-project.afterEvaluate {
-	copy {
-		from configurations.tor.collect { zipTree(it) }
-		into 'src/main/resources'
+def torBinariesDir = 'src/main/resources'
+
+task cleanTorBinaries {
+	doLast {
+		delete fileTree(torBinariesDir) { include '*.zip' }
 	}
 }
 
+clean.dependsOn cleanTorBinaries
+
+task unpackTorBinaries {
+	doLast {
+		copy {
+			from configurations.tor.collect { zipTree(it) }
+			into torBinariesDir
+		}
+	}
+	dependsOn cleanTorBinaries
+}
+
+processResources {
+	inputs.dir torBinariesDir
+	dependsOn unpackTorBinaries
+}
+
 tasks.withType(Test) {
 	systemProperty 'java.library.path', 'libs'
 }

bramble-java/src/main/java/org/briarproject/bramble/network/JavaNetworkManager.java

@@ -1,10 +1,7 @@
 package org.briarproject.bramble.network;
 
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.lifecycle.Service;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.network.NetworkStatus;
-import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 
@@ -23,25 +20,13 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class JavaNetworkManager implements NetworkManager, Service {
+class JavaNetworkManager implements NetworkManager {
 
 	private static final Logger LOG =
 			Logger.getLogger(JavaNetworkManager.class.getName());
 
-	private final EventBus eventBus;
-
 	@Inject
-	JavaNetworkManager(EventBus eventBus) {
-		this.eventBus = eventBus;
-	}
-
-	@Override
-	public void startService() {
-		eventBus.broadcast(new NetworkStatusEvent(getNetworkStatus()));
-	}
-
-	@Override
-	public void stopService() {
+	JavaNetworkManager() {
 	}
 
 	@Override

bramble-java/src/main/java/org/briarproject/bramble/network/JavaNetworkModule.java

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.network;
 
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.network.NetworkManager;
 
 import javax.inject.Singleton;
@@ -13,9 +12,7 @@ public class JavaNetworkModule {
 
 	@Provides
 	@Singleton
-	NetworkManager provideNetworkManager(LifecycleManager lifecycleManager,
-			JavaNetworkManager networkManager) {
-		lifecycleManager.registerService(networkManager);
+	NetworkManager provideNetworkManager(JavaNetworkManager networkManager) {
 		return networkManager;
 	}
 }

bramble-java/src/main/java/org/briarproject/bramble/plugin/modem/ModemImpl.java

@@ -10,6 +10,10 @@ import org.briarproject.bramble.api.system.Clock;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.nio.ByteBuffer;
+import java.nio.charset.CharacterCodingException;
+import java.nio.charset.Charset;
+import java.nio.charset.CharsetDecoder;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.locks.Condition;
@@ -22,6 +26,7 @@ import javax.annotation.Nullable;
 import jssc.SerialPortEvent;
 import jssc.SerialPortEventListener;
 
+import static java.nio.charset.CodingErrorAction.IGNORE;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
@@ -35,6 +40,8 @@ class ModemImpl implements Modem, WriteHandler, SerialPortEventListener {
 
 	private static final Logger LOG =
 			Logger.getLogger(ModemImpl.class.getName());
+
+	private static final Charset US_ASCII = Charset.forName("US-ASCII");
 	private static final int MAX_LINE_LENGTH = 256;
 	private static final int[] BAUD_RATES = {
 		256000, 128000, 115200, 57600, 38400, 19200, 14400, 9600, 4800, 1200
@@ -106,7 +113,7 @@ class ModemImpl implements Modem, WriteHandler, SerialPortEventListener {
 				throw e;
 			}
 			// Wait for the event thread to receive "OK"
-			boolean success = false;
+			boolean success;
 			try {
 				lock.lock();
 				try {
@@ -353,8 +360,7 @@ class ModemImpl implements Modem, WriteHandler, SerialPortEventListener {
 		for (int i = 0; i < b.length; i++) {
 			line[lineLen] = b[i];
 			if (b[i] == '\n') {
-				// FIXME: Use CharsetDecoder to catch invalid ASCII
-				String s = new String(line, 0, lineLen, "US-ASCII").trim();
+				String s = toAscii(line, lineLen).trim();
 				lineLen = 0;
 				if (LOG.isLoggable(INFO)) LOG.info("Modem status: " + s);
 				if (s.startsWith("CONNECT")) {
@@ -436,7 +442,7 @@ class ModemImpl implements Modem, WriteHandler, SerialPortEventListener {
 				throw e;
 			}
 			// Wait for the event thread to receive "CONNECT"
-			boolean success = false;
+			boolean success;
 			try {
 				lock.lock();
 				try {
@@ -461,4 +467,16 @@ class ModemImpl implements Modem, WriteHandler, SerialPortEventListener {
 			stateChange.release();
 		}
 	}
+
+	private String toAscii(byte[] bytes, int len) {
+		CharsetDecoder decoder = US_ASCII.newDecoder();
+		decoder.onMalformedInput(IGNORE);
+		decoder.onUnmappableCharacter(IGNORE);
+		ByteBuffer buffer = ByteBuffer.wrap(bytes, 0, len);
+		try {
+			return decoder.decode(buffer).toString();
+		} catch (CharacterCodingException e) {
+			throw new AssertionError(e);
+		}
+	}
 }

bramble-java/src/main/java/org/briarproject/bramble/plugin/tor/LinuxTorPlugin.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.plugin.tor;
 
+import org.briarproject.bramble.api.battery.BatteryManager;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
@@ -23,12 +24,14 @@ class LinuxTorPlugin extends TorPlugin {
 	LinuxTorPlugin(Executor ioExecutor, NetworkManager networkManager,
 			LocationUtils locationUtils, SocketFactory torSocketFactory,
 			Clock clock, ResourceProvider resourceProvider,
-			CircumventionProvider circumventionProvider, Backoff backoff,
+			CircumventionProvider circumventionProvider,
+			BatteryManager batteryManager, Backoff backoff,
 			DuplexPluginCallback callback, String architecture, int maxLatency,
 			int maxIdleTime, File torDirectory) {
 		super(ioExecutor, networkManager, locationUtils, torSocketFactory,
-				clock, resourceProvider, circumventionProvider, backoff,
-				callback, architecture, maxLatency, maxIdleTime, torDirectory);
+				clock, resourceProvider, circumventionProvider, batteryManager,
+				backoff, callback, architecture, maxLatency, maxIdleTime,
+				torDirectory);
 	}
 
 	@Override

bramble-java/src/main/java/org/briarproject/bramble/plugin/tor/LinuxTorPluginFactory.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.plugin.tor;
 
+import org.briarproject.bramble.api.battery.BatteryManager;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -44,6 +45,7 @@ public class LinuxTorPluginFactory implements DuplexPluginFactory {
 	private final BackoffFactory backoffFactory;
 	private final ResourceProvider resourceProvider;
 	private final CircumventionProvider circumventionProvider;
+	private final BatteryManager batteryManager;
 	private final Clock clock;
 	private final File torDirectory;
 
@@ -51,8 +53,8 @@ public class LinuxTorPluginFactory implements DuplexPluginFactory {
 			NetworkManager networkManager, LocationUtils locationUtils,
 			EventBus eventBus, SocketFactory torSocketFactory,
 			BackoffFactory backoffFactory, ResourceProvider resourceProvider,
-			CircumventionProvider circumventionProvider, Clock clock,
-			File torDirectory) {
+			CircumventionProvider circumventionProvider,
+			BatteryManager batteryManager, Clock clock, File torDirectory) {
 		this.ioExecutor = ioExecutor;
 		this.networkManager = networkManager;
 		this.locationUtils = locationUtils;
@@ -61,6 +63,7 @@ public class LinuxTorPluginFactory implements DuplexPluginFactory {
 		this.backoffFactory = backoffFactory;
 		this.resourceProvider = resourceProvider;
 		this.circumventionProvider = circumventionProvider;
+		this.batteryManager = batteryManager;
 		this.clock = clock;
 		this.torDirectory = torDirectory;
 	}
@@ -92,11 +95,10 @@ public class LinuxTorPluginFactory implements DuplexPluginFactory {
 
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		LinuxTorPlugin plugin =
-				new LinuxTorPlugin(ioExecutor, networkManager, locationUtils,
-						torSocketFactory, clock, resourceProvider,
-						circumventionProvider, backoff, callback, architecture,
-						MAX_LATENCY, MAX_IDLE_TIME, torDirectory);
+		LinuxTorPlugin plugin = new LinuxTorPlugin(ioExecutor, networkManager,
+				locationUtils, torSocketFactory, clock, resourceProvider,
+				circumventionProvider, batteryManager, backoff, callback,
+				architecture, MAX_LATENCY, MAX_IDLE_TIME, torDirectory);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

bramble-java/src/test/java/org/briarproject/bramble/plugin/tor/BridgeTest.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.plugin.tor;
 
+import org.briarproject.bramble.api.battery.BatteryManager;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.plugin.BackoffFactory;
@@ -58,6 +59,8 @@ public class BridgeTest extends BrambleTestCase {
 	@Inject
 	CircumventionProvider circumventionProvider;
 	@Inject
+	BatteryManager batteryManager;
+	@Inject
 	EventBus eventBus;
 	@Inject
 	BackoffFactory backoffFactory;
@@ -107,7 +110,8 @@ public class BridgeTest extends BrambleTestCase {
 		};
 		factory = new LinuxTorPluginFactory(ioExecutor, networkManager,
 				locationUtils, eventBus, torSocketFactory, backoffFactory,
-				resourceProvider, bridgeProvider, clock, torDir);
+				resourceProvider, bridgeProvider, batteryManager, clock,
+				torDir);
 	}
 
 	@After

bramble-java/src/test/java/org/briarproject/bramble/test/BrambleJavaIntegrationTestComponent.java

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.test;
 
 import org.briarproject.bramble.BrambleJavaModule;
+import org.briarproject.bramble.battery.DefaultBatteryManagerModule;
 import org.briarproject.bramble.event.EventModule;
 import org.briarproject.bramble.plugin.PluginModule;
 import org.briarproject.bramble.plugin.tor.BridgeTest;
@@ -15,6 +16,7 @@ import dagger.Component;
 @Component(modules = {
 		BrambleJavaModule.class,
 		TestLifecycleModule.class,
+		DefaultBatteryManagerModule.class,
 		PluginModule.class,  // needed for BackoffFactory
 		EventModule.class,
 		SystemModule.class,

bramble-java/witness.gradle

@@ -1,10 +1,18 @@
 dependencyVerification {
     verify = [
         'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
-        'com.google.dagger:dagger-compiler:2.0.2:dagger-compiler-2.0.2.jar:b74bc9de063dd4c6400b232231f2ef5056145b8fbecbf5382012007dd1c071b3',
-        'com.google.dagger:dagger-producers:2.0-beta:dagger-producers-2.0-beta.jar:99ec15e8a0507ba569e7655bc1165ee5e5ca5aa914b3c8f7e2c2458f724edd6b',
-        'com.google.dagger:dagger:2.0.2:dagger-2.0.2.jar:84c0282ed8be73a29e0475d639da030b55dee72369e58dd35ae7d4fe6243dcf9',
-        'com.google.guava:guava:18.0:guava-18.0.jar:d664fbfc03d2e5ce9cab2a44fb01f1d0bf9dfebeccc1a473b1f9ea31f79f6f99',
+        'com.google.code.findbugs:jsr305:1.3.9:jsr305-1.3.9.jar:905721a0eea90a81534abb7ee6ef4ea2e5e645fa1def0a5cd88402df1b46c9ed',
+        'com.google.dagger:dagger-compiler:2.19:dagger-compiler-2.19.jar:27a4b202a2de908182edb261f8c0a264e08e5e4733d7514bc7fbf0d31da5c0fc',
+        'com.google.dagger:dagger-producers:2.19:dagger-producers-2.19.jar:a17663abe0fc38b676026950907d4c5f5e2bf338375415861eaff6e3bdb0b768',
+        'com.google.dagger:dagger-spi:2.19:dagger-spi-2.19.jar:e7a6379d82c841f6aac2866948ad1eed716528707814602842a8d844ce04e2e1',
+        'com.google.dagger:dagger:2.19:dagger-2.19.jar:514b6f1e0727c6572e1d65cb27e4ae668b7aeaeb93a29515182965265b609939',
+        'com.google.errorprone:error_prone_annotations:2.1.3:error_prone_annotations-2.1.3.jar:03d0329547c13da9e17c634d1049ea2ead093925e290567e1a364fd6b1fc7ff8',
+        'com.google.errorprone:javac-shaded:9-dev-r4023-3:javac-shaded-9-dev-r4023-3.jar:65bfccf60986c47fbc17c9ebab0be626afc41741e0a6ec7109e0768817a36f30',
+        'com.google.googlejavaformat:google-java-format:1.5:google-java-format-1.5.jar:aa19ad7850fb85178aa22f2fddb163b84d6ce4d0035872f30d4408195ca1144e',
+        'com.google.guava:guava:25.0-jre:guava-25.0-jre.jar:3fd4341776428c7e0e5c18a7c10de129475b69ab9d30aeafbb5c277bb6074fa9',
+        'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:40ceb7157feb263949e0f503fe5f71689333a621021aa20ce0d0acee3badaa0f',
+        'com.squareup:javapoet:1.11.1:javapoet-1.11.1.jar:9cbf2107be499ec6e95afd36b58e3ca122a24166cdd375732e51267d64058e90',
+        'javax.annotation:jsr250-api:1.0:jsr250-api-1.0.jar:a1a922d0d9b6d183ed3800dfac01d1e1eb159f0e8c6f94736931c1def54a941f',
         'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
         'junit:junit:4.12:junit-4.12.jar:59721f0805e223d84b90677887d9ff567dc534d7c502ca903c0c2b17f05c116a',
         'net.java.dev.jna:jna-platform:4.5.2:jna-platform-4.5.2.jar:f1d00c167d8921c6e23c626ef9f1c3ae0be473c95c68ffa012bc7ae55a87e2d6',
@@ -12,7 +20,10 @@ dependencyVerification {
         'org.apache.ant:ant-launcher:1.9.4:ant-launcher-1.9.4.jar:7bccea20b41801ca17bcbc909a78c835d0f443f12d639c77bd6ae3d05861608d',
         'org.apache.ant:ant:1.9.4:ant-1.9.4.jar:649ae0730251de07b8913f49286d46bba7b92d47c5f332610aa426c4f02161d8',
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
+        'org.briarproject:obfs4proxy:0.0.7:obfs4proxy-0.0.7.zip:5b2f693262ce43a7e130f7cc7d5d1617925330640a2eb6d71085e95df8ee0642',
         'org.briarproject:tor:0.3.4.8:tor-0.3.4.8.zip:bc0158c34002f471a4fe14a6a481816c918eb520a220bb027f64be902beb757f',
+        'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
+        'org.codehaus.mojo:animal-sniffer-annotations:1.14:animal-sniffer-annotations-1.14.jar:2068320bd6bad744c3673ab048f67e30bef8f518996fa380033556600669905d',
         'org.hamcrest:hamcrest-core:1.3:hamcrest-core-1.3.jar:66fdef91e9739348df7a096aa384a5685f4e875584cce89386a7a47251c4d8e9',
         'org.hamcrest:hamcrest-library:1.3:hamcrest-library-1.3.jar:711d64522f9ec410983bd310934296da134be4254a125080a0416ec178dfad1c',
         'org.jmock:jmock-junit4:2.8.2:jmock-junit4-2.8.2.jar:f7ee4df4f7bd7b7f1cafad3b99eb74d579f109d5992ff625347352edb55e674c',

briar-android/build.gradle

@@ -22,8 +22,8 @@ android {
 	defaultConfig {
 		minSdkVersion 15
 		targetSdkVersion 26
-		versionCode 10103
-		versionName "1.1.3"
+		versionCode 10105
+		versionName "1.1.5"
 		applicationId "org.briarproject.briar.android"
 		buildConfigField "String", "GitHash",
 				"\"${getStdout(['git', 'rev-parse', '--short=7', 'HEAD'], 'No commit hash')}\""
@@ -118,27 +118,25 @@ dependencies {
 	implementation 'uk.co.samuelwall:material-tap-target-prompt:2.12.4'
 	implementation 'com.vanniktech:emoji-google:0.5.1'
 
-	annotationProcessor 'com.google.dagger:dagger-compiler:2.0.2'
+	annotationProcessor 'com.google.dagger:dagger-compiler:2.19'
 
 	compileOnly 'javax.annotation:jsr250-api:1.0'
 
 	testImplementation project(path: ':bramble-api', configuration: 'testOutput')
 	testImplementation project(path: ':bramble-core', configuration: 'testOutput')
-	testImplementation 'org.robolectric:robolectric:3.8'
+	testImplementation 'org.robolectric:robolectric:4.0.1'
 	testImplementation 'org.robolectric:shadows-support-v4:3.3.2'
 	testImplementation 'org.mockito:mockito-core:2.13.0'
 	testImplementation 'junit:junit:4.12'
 	testImplementation "org.jmock:jmock:2.8.2"
 	testImplementation "org.jmock:jmock-junit4:2.8.2"
 	testImplementation "org.jmock:jmock-legacy:2.8.2"
-	testImplementation "org.hamcrest:hamcrest-library:1.3"
-	testImplementation "org.hamcrest:hamcrest-core:1.3"
 
 	def espressoVersion = '3.0.2'
 	androidTestImplementation "com.android.support.test.espresso:espresso-core:$espressoVersion"
 	androidTestImplementation "com.android.support.test.espresso:espresso-contrib:$espressoVersion"
 	androidTestImplementation "com.android.support.test.espresso:espresso-intents:$espressoVersion"
-	androidTestAnnotationProcessor "com.google.dagger:dagger-compiler:2.0.2"
+	androidTestAnnotationProcessor "com.google.dagger:dagger-compiler:2.19"
 	androidTestCompileOnly 'javax.annotation:jsr250-api:1.0'
 	androidTestImplementation 'junit:junit:4.12'
 	androidTestScreenshotImplementation "tools.fastlane:screengrab:1.2.0"

briar-android/src/androidTest/java/org/briarproject/briar/android/BriarTestComponentApplication.java

@@ -1,5 +1,6 @@
 package org.briarproject.briar.android;
 
+import org.briarproject.bramble.BrambleAndroidModule;
 import org.briarproject.bramble.BrambleCoreModule;
 import org.briarproject.briar.BriarCoreModule;
 
@@ -12,6 +13,7 @@ public class BriarTestComponentApplication extends BriarApplicationImpl {
 		// We need to load the eager singletons directly after making the
 		// dependency graphs
 		BrambleCoreModule.initEagerSingletons(component);
+		BrambleAndroidModule.initEagerSingletons(component);
 		BriarCoreModule.initEagerSingletons(component);
 		AndroidEagerSingletons.initEagerSingletons(component);
 		return component;

briar-android/src/main/AndroidManifest.xml

@@ -7,7 +7,6 @@
 	<uses-feature android:name="android.hardware.camera" android:required="false"/>
 	<uses-feature android:name="android.hardware.touchscreen" android:required="false" />
 
-	<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
 	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 	<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
 	<uses-permission android:name="android.permission.BLUETOOTH" />
@@ -18,6 +17,7 @@
 	<uses-permission android:name="android.permission.USE_FINGERPRINT"/>
 	<uses-permission android:name="android.permission.VIBRATE" />
 	<uses-permission android:name="android.permission.WAKE_LOCK" />
+	<uses-permission-sdk-23 android:name="android.permission.ACCESS_COARSE_LOCATION" />
 	<uses-permission-sdk-23 android:name="android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS"/>
 	<uses-permission-sdk-23 android:name="android.permission.USE_BIOMETRIC" />
 
@@ -102,7 +102,7 @@
 		</activity>
 
 		<activity
-			android:name="org.briarproject.briar.android.contact.ConversationActivity"
+			android:name="org.briarproject.briar.android.conversation.ConversationActivity"
 			android:label="@string/app_name"
 			android:theme="@style/BriarTheme.NoActionBar"
 			android:parentActivityName="org.briarproject.briar.android.navdrawer.NavDrawerActivity"
@@ -190,10 +190,10 @@
 		<activity
 			android:name="org.briarproject.briar.android.sharing.BlogInvitationActivity"
 			android:label="@string/blogs_sharing_invitations_title"
-			android:parentActivityName="org.briarproject.briar.android.contact.ConversationActivity">
+			android:parentActivityName="org.briarproject.briar.android.conversation.ConversationActivity">
 			<meta-data
 				android:name="android.support.PARENT_ACTIVITY"
-				android:value="org.briarproject.briar.android.contact.ConversationActivity"
+				android:value="org.briarproject.briar.android.conversation.ConversationActivity"
 				/>
 		</activity>
 
@@ -327,11 +327,11 @@
 		<activity
 			android:name="org.briarproject.briar.android.introduction.IntroductionActivity"
 			android:label="@string/introduction_activity_title"
-			android:parentActivityName="org.briarproject.briar.android.contact.ConversationActivity"
+			android:parentActivityName="org.briarproject.briar.android.conversation.ConversationActivity"
 			android:windowSoftInputMode="stateHidden|adjustResize">
 			<meta-data
 				android:name="android.support.PARENT_ACTIVITY"
-				android:value="org.briarproject.briar.android.contact.ConversationActivity"
+				android:value="org.briarproject.briar.android.conversation.ConversationActivity"
 				/>
 		</activity>
 

briar-android/src/main/java/org/briarproject/briar/android/AndroidComponent.java

@@ -1,5 +1,8 @@
 package org.briarproject.briar.android;
 
+import android.arch.lifecycle.ViewModelProvider;
+
+import org.briarproject.bramble.BrambleAndroidEagerSingletons;
 import org.briarproject.bramble.BrambleAndroidModule;
 import org.briarproject.bramble.BrambleCoreEagerSingletons;
 import org.briarproject.bramble.BrambleCoreModule;
@@ -26,7 +29,6 @@ import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.plugin.tor.CircumventionProvider;
 import org.briarproject.briar.BriarCoreEagerSingletons;
 import org.briarproject.briar.BriarCoreModule;
-import org.briarproject.briar.android.contact.ConversationViewModel;
 import org.briarproject.briar.android.login.SignInReminderReceiver;
 import org.briarproject.briar.android.reporting.BriarReportSender;
 import org.briarproject.briar.android.view.TextInputView;
@@ -38,11 +40,11 @@ import org.briarproject.briar.api.blog.BlogManager;
 import org.briarproject.briar.api.blog.BlogPostFactory;
 import org.briarproject.briar.api.blog.BlogSharingManager;
 import org.briarproject.briar.api.client.MessageTracker;
+import org.briarproject.briar.api.conversation.ConversationManager;
 import org.briarproject.briar.api.feed.FeedManager;
 import org.briarproject.briar.api.forum.ForumManager;
 import org.briarproject.briar.api.forum.ForumSharingManager;
 import org.briarproject.briar.api.introduction.IntroductionManager;
-import org.briarproject.briar.api.messaging.ConversationManager;
 import org.briarproject.briar.api.messaging.MessagingManager;
 import org.briarproject.briar.api.messaging.PrivateMessageFactory;
 import org.briarproject.briar.api.privategroup.GroupMessageFactory;
@@ -67,7 +69,8 @@ import dagger.Component;
 		AppModule.class
 })
 public interface AndroidComponent
-		extends BrambleCoreEagerSingletons, BriarCoreEagerSingletons {
+		extends BrambleCoreEagerSingletons, BrambleAndroidEagerSingletons,
+		BriarCoreEagerSingletons {
 
 	// Exposed objects
 	@CryptoExecutor
@@ -155,6 +158,8 @@ public interface AndroidComponent
 
 	CircumventionProvider circumventionProvider();
 
+	ViewModelProvider.Factory viewModelFactory();
+
 	void inject(SignInReminderReceiver briarService);
 
 	void inject(BriarService briarService);
@@ -165,8 +170,6 @@ public interface AndroidComponent
 
 	void inject(TextInputView textInputView);
 
-	void inject(ConversationViewModel conversationViewModel);
-
 	// Eager singleton load
 	void inject(AppModule.EagerSingletons init);
 }

briar-android/src/main/java/org/briarproject/briar/android/AndroidNotificationManagerImpl.java

@@ -31,7 +31,7 @@ import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.contact.ConversationActivity;
+import org.briarproject.briar.android.conversation.ConversationActivity;
 import org.briarproject.briar.android.forum.ForumActivity;
 import org.briarproject.briar.android.login.SignInReminderReceiver;
 import org.briarproject.briar.android.navdrawer.NavDrawerActivity;
@@ -40,9 +40,9 @@ import org.briarproject.briar.android.splash.SplashScreenActivity;
 import org.briarproject.briar.android.util.BriarNotificationBuilder;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.blog.event.BlogPostAddedEvent;
+import org.briarproject.briar.api.conversation.event.ConversationMessageReceivedEvent;
 import org.briarproject.briar.api.forum.event.ForumPostReceivedEvent;
 import org.briarproject.briar.api.introduction.event.IntroductionSucceededEvent;
-import org.briarproject.briar.api.messaging.event.PrivateMessageReceivedEvent;
 import org.briarproject.briar.api.privategroup.event.GroupMessageAddedEvent;
 
 import java.util.Set;
@@ -72,7 +72,7 @@ import static android.support.v4.app.NotificationCompat.PRIORITY_MIN;
 import static android.support.v4.app.NotificationCompat.VISIBILITY_SECRET;
 import static android.support.v4.content.ContextCompat.getColor;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.contact.ConversationActivity.CONTACT_ID;
+import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
 import static org.briarproject.briar.android.navdrawer.NavDrawerActivity.INTENT_BLOGS;
 import static org.briarproject.briar.android.navdrawer.NavDrawerActivity.INTENT_CONTACTS;
 import static org.briarproject.briar.android.navdrawer.NavDrawerActivity.INTENT_FORUMS;
@@ -219,8 +219,9 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 			SettingsUpdatedEvent s = (SettingsUpdatedEvent) e;
 			if (s.getNamespace().equals(SETTINGS_NAMESPACE))
 				settings = s.getSettings();
-		} else if (e instanceof PrivateMessageReceivedEvent) {
-			PrivateMessageReceivedEvent p = (PrivateMessageReceivedEvent) e;
+		} else if (e instanceof ConversationMessageReceivedEvent) {
+			ConversationMessageReceivedEvent p =
+					(ConversationMessageReceivedEvent) e;
 			showContactNotification(p.getContactId());
 		} else if (e instanceof GroupMessageAddedEvent) {
 			GroupMessageAddedEvent g = (GroupMessageAddedEvent) e;

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -7,6 +7,7 @@ import android.os.StrictMode;
 
 import com.vanniktech.emoji.RecentEmoji;
 
+import org.briarproject.bramble.api.battery.BatteryManager;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.db.DatabaseConfig;
@@ -32,6 +33,7 @@ import org.briarproject.bramble.plugin.tor.CircumventionProvider;
 import org.briarproject.bramble.util.AndroidUtils;
 import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.android.account.LockManagerImpl;
+import org.briarproject.briar.android.viewmodel.ViewModelModule;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.android.DozeWatchdog;
 import org.briarproject.briar.api.android.LockManager;
@@ -57,17 +59,21 @@ import static java.util.Collections.emptyList;
 import static org.briarproject.bramble.api.reporting.ReportingConstants.DEV_ONION_ADDRESS;
 import static org.briarproject.bramble.api.reporting.ReportingConstants.DEV_PUBLIC_KEY_HEX;
 
-@Module
+@Module(includes = ViewModelModule.class)
 public class AppModule {
 
 	static class EagerSingletons {
 		@Inject
 		AndroidNotificationManager androidNotificationManager;
 		@Inject
+		ScreenFilterMonitor screenFilterMonitor;
+		@Inject
 		NetworkUsageLogger networkUsageLogger;
 		@Inject
 		DozeWatchdog dozeWatchdog;
 		@Inject
+		LockManager lockManager;
+		@Inject
 		RecentEmoji recentEmoji;
 	}
 
@@ -103,7 +109,8 @@ public class AppModule {
 			Application app, NetworkManager networkManager,
 			LocationUtils locationUtils, EventBus eventBus,
 			ResourceProvider resourceProvider,
-			CircumventionProvider circumventionProvider, Clock clock) {
+			CircumventionProvider circumventionProvider,
+			BatteryManager batteryManager, Clock clock) {
 		Context appContext = app.getApplicationContext();
 		DuplexPluginFactory bluetooth =
 				new AndroidBluetoothPluginFactory(ioExecutor, androidExecutor,
@@ -111,7 +118,7 @@ public class AppModule {
 		DuplexPluginFactory tor = new AndroidTorPluginFactory(ioExecutor,
 				scheduler, appContext, networkManager, locationUtils, eventBus,
 				torSocketFactory, backoffFactory, resourceProvider,
-				circumventionProvider, clock);
+				circumventionProvider, batteryManager, clock);
 		DuplexPluginFactory lan = new AndroidLanTcpPluginFactory(ioExecutor,
 				eventBus, backoffFactory, appContext);
 		Collection<DuplexPluginFactory> duplex = asList(bluetooth, tor, lan);

briar-android/src/main/java/org/briarproject/briar/android/BriarApplicationImpl.java

@@ -15,6 +15,7 @@ import com.vanniktech.emoji.google.GoogleEmojiProvider;
 import org.acra.ACRA;
 import org.acra.ReportingInteractionMode;
 import org.acra.annotation.ReportsCrashes;
+import org.briarproject.bramble.BrambleAndroidModule;
 import org.briarproject.bramble.BrambleCoreModule;
 import org.briarproject.briar.BriarCoreModule;
 import org.briarproject.briar.R;
@@ -124,6 +125,7 @@ public class BriarApplicationImpl extends Application
 		// We need to load the eager singletons directly after making the
 		// dependency graphs
 		BrambleCoreModule.initEagerSingletons(androidComponent);
+		BrambleAndroidModule.initEagerSingletons(androidComponent);
 		BriarCoreModule.initEagerSingletons(androidComponent);
 		AndroidEagerSingletons.initEagerSingletons(androidComponent);
 		return androidComponent;

briar-android/src/main/java/org/briarproject/briar/android/RecentEmojiImpl.java

@@ -18,8 +18,7 @@ import org.briarproject.bramble.util.StringUtils;
 
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Iterator;
-import java.util.LinkedHashSet;
+import java.util.LinkedList;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
@@ -40,7 +39,7 @@ class RecentEmojiImpl implements RecentEmoji, Client {
 	private static final int EMOJI_LRU_SIZE = 50;
 
 	// UI thread
-	private final LinkedHashSet<Emoji> recentlyUsed = new LinkedHashSet<>();
+	private final LinkedList<Emoji> recentlyUsed = new LinkedList<>();
 
 	private final Executor dbExecutor;
 	private final AndroidExecutor androidExecutor;
@@ -62,13 +61,9 @@ class RecentEmojiImpl implements RecentEmoji, Client {
 	@Override
 	public void addEmoji(Emoji emoji) {
 		recentlyUsed.remove(emoji);
-		recentlyUsed.add(emoji);
+		recentlyUsed.add(0, emoji);
 
-		if (recentlyUsed.size() > EMOJI_LRU_SIZE) {
-			Iterator<Emoji> iterator = recentlyUsed.iterator();
-			iterator.next();
-			iterator.remove();
-		}
+		if (recentlyUsed.size() > EMOJI_LRU_SIZE) recentlyUsed.removeLast();
 	}
 
 	@Override