Poll Tor plugin infrequently once our HS is reachable.

.idea/codeStyles/Project.xml

@@ -1,5 +1,8 @@
 <component name="ProjectCodeStyleConfiguration">
   <code_scheme name="Project" version="173">
+    <AndroidXmlCodeStyleSettings>
+      <option name="ARRANGEMENT_SETTINGS_MIGRATED_TO_191" value="true" />
+    </AndroidXmlCodeStyleSettings>
     <JavaCodeStyleSettings>
       <option name="ANNOTATION_PARAMETER_WRAP" value="1" />
       <option name="IMPORT_LAYOUT_TABLE">
@@ -28,11 +31,6 @@
       <option name="JD_ALIGN_EXCEPTION_COMMENTS" value="false" />
     </JavaCodeStyleSettings>
     <JetCodeStyleSettings>
-      <option name="PACKAGES_TO_USE_STAR_IMPORTS">
-        <value />
-      </option>
-      <option name="NAME_COUNT_TO_USE_STAR_IMPORT" value="2147483647" />
-      <option name="NAME_COUNT_TO_USE_STAR_IMPORT_FOR_MEMBERS" value="2147483647" />
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
     </JetCodeStyleSettings>
     <XML>

TRANSLATION.md

@@ -1,9 +0,0 @@
-Translations for this project are managed through Transifex:
-
-https://transifex.com/otf/briar
-
-If you'd like to volunteer as a translator, please create a Transifex account and request to be
-added to the project's translation team. The Localization Lab has some instructions and advice for
-translators here:
-
-https://wiki.localizationlab.org/index.php/Briar

bramble-android/.gitignore

@@ -3,4 +3,3 @@ gen
 build
 .settings
 src/main/res/raw/*.zip
-src/main/jniLibs

bramble-android/build.gradle

@@ -5,14 +5,14 @@ apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 android {
-	compileSdkVersion rootProject.ext.compileSdkVersion
+	compileSdkVersion 29
-	buildToolsVersion rootProject.ext.buildToolsVersion
+	buildToolsVersion '29.0.2'
 
 	defaultConfig {
-		minSdkVersion rootProject.ext.minSdkVersion
+		minSdkVersion 16
-		targetSdkVersion rootProject.ext.targetSdkVersion
+		targetSdkVersion 28
-		versionCode rootProject.ext.versionCode
+		versionCode 10207
-		versionName rootProject.ext.versionName
+		versionName "1.2.7"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
@@ -53,12 +53,10 @@ dependencies {
 }
 
 def torBinariesDir = 'src/main/res/raw'
-def torLibsDir = 'src/main/jniLibs'
 
 task cleanTorBinaries {
 	doLast {
 		delete fileTree(torBinariesDir) { include '*.zip' }
-		delete fileTree(torLibsDir) { include '**/*.so' }
 	}
 }
 
@@ -69,36 +67,8 @@ task unpackTorBinaries {
 		copy {
 			from configurations.tor.collect { zipTree(it) }
 			into torBinariesDir
-			include 'geoip.zip'
+			// TODO: Remove after next Tor upgrade, which won't include non-PIE binaries
-		}
+			include 'geoip.zip', '*_pie.zip'
-		configurations.tor.each { outer ->
-			zipTree(outer).each { inner ->
-				if (inner.name.endsWith('_arm_pie.zip')) {
-					copy {
-						from zipTree(inner)
-						into torLibsDir
-						rename '(.*)', 'armeabi-v7a/lib$1.so'
-					}
-				} else if (inner.name.endsWith('_arm64_pie.zip')) {
-					copy {
-						from zipTree(inner)
-						into torLibsDir
-						rename '(.*)', 'arm64-v8a/lib$1.so'
-					}
-				} else if (inner.name.endsWith('_x86_pie.zip')) {
-					copy {
-						from zipTree(inner)
-						into torLibsDir
-						rename '(.*)', 'x86/lib$1.so'
-					}
-				} else if (inner.name.endsWith('_x86_64_pie.zip')) {
-					copy {
-						from zipTree(inner)
-						into torLibsDir
-						rename '(.*)', 'x86_64/lib$1.so'
-					}
-				}
-			}
 		}
 	}
 	dependsOn cleanTorBinaries
@@ -106,6 +76,5 @@ task unpackTorBinaries {
 
 tasks.withType(MergeResources) {
 	inputs.dir torBinariesDir
-	inputs.dir torLibsDir
 	dependsOn unpackTorBinaries
 }

bramble-android/src/main/AndroidManifest.xml

@@ -16,8 +16,6 @@
 		android:label="@string/app_name"
 		android:supportsRtl="true">
 
-		<receiver android:name=".system.AlarmReceiver" />
-
 	</application>
 
 </manifest>

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

@@ -6,8 +6,6 @@ import org.briarproject.bramble.plugin.tor.CircumventionModule;
 import org.briarproject.bramble.reporting.ReportingModule;
 import org.briarproject.bramble.socks.SocksModule;
 import org.briarproject.bramble.system.AndroidSystemModule;
-import org.briarproject.bramble.system.AndroidTaskSchedulerModule;
-import org.briarproject.bramble.system.AndroidWakefulIoExecutorModule;
 
 import dagger.Module;
 
@@ -15,8 +13,6 @@ import dagger.Module;
 		AndroidBatteryModule.class,
 		AndroidNetworkModule.class,
 		AndroidSystemModule.class,
-		AndroidTaskSchedulerModule.class,
-		AndroidWakefulIoExecutorModule.class,
 		CircumventionModule.class,
 		ReportingModule.class,
 		SocksModule.class

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

@@ -1,8 +0,0 @@
-package org.briarproject.bramble;
-
-import org.briarproject.bramble.api.system.AlarmListener;
-
-public interface BrambleAppComponent {
-
-	AlarmListener alarmListener();
-}

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

@@ -1,6 +0,0 @@
-package org.briarproject.bramble;
-
-public interface BrambleApplication {
-
-	BrambleAppComponent getBrambleAppComponent();
-}

bramble-android/src/main/java/org/briarproject/bramble/api/system/AlarmListener.java

@@ -1,11 +0,0 @@
-package org.briarproject.bramble.api.system;
-
-import android.content.Intent;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-@NotNullByDefault
-public interface AlarmListener {
-
-	void onAlarm(Intent intent);
-}

bramble-android/src/main/java/org/briarproject/bramble/api/system/AndroidWakeLock.java

@@ -1,19 +0,0 @@
-package org.briarproject.bramble.api.system;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-@NotNullByDefault
-public interface AndroidWakeLock {
-
-	/**
-	 * Acquires the wake lock. This has no effect if the wake lock has already
-	 * been acquired.
-	 */
-	void acquire();
-
-	/**
-	 * Releases the wake lock. This has no effect if the wake lock has already
-	 * been released.
-	 */
-	void release();
-}

bramble-android/src/main/java/org/briarproject/bramble/api/system/AndroidWakeLockManager.java

@@ -1,38 +0,0 @@
-package org.briarproject.bramble.api.system;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.util.concurrent.Executor;
-
-@NotNullByDefault
-public interface AndroidWakeLockManager {
-
-	/**
-	 * Creates a wake lock with the given tag. The tag is only used for
-	 * logging; the underlying OS wake lock will use its own tag.
-	 */
-	AndroidWakeLock createWakeLock(String tag);
-
-	/**
-	 * Runs the given task while holding a wake lock.
-	 */
-	void runWakefully(Runnable r, String tag);
-
-	/**
-	 * Submits the given task to the given executor while holding a wake lock.
-	 * The lock is released when the task completes, or if an exception is
-	 * thrown while submitting or running the task.
-	 */
-	void executeWakefully(Runnable r, Executor executor, String tag);
-
-	/**
-	 * Starts a dedicated thread to run the given task asynchronously. A wake
-	 * lock is acquired before starting the thread and released when the task
-	 * completes, or if an exception is thrown while starting the thread or
-	 * running the task.
-	 * <p>
-	 * This method should only be used for lifecycle management tasks that
-	 * can't be run on an executor.
-	 */
-	void executeWakefully(Runnable r, String tag);
-}

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

@@ -9,17 +9,16 @@ import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 
 import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.event.EventExecutor;
 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;
-import org.briarproject.bramble.api.system.TaskScheduler;
+import org.briarproject.bramble.api.system.Scheduler;
-import org.briarproject.bramble.api.system.TaskScheduler.Cancellable;
 
-import java.util.concurrent.Executor;
+import java.util.concurrent.Future;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
@@ -51,22 +50,20 @@ class AndroidNetworkManager implements NetworkManager, Service {
 	private static final String WIFI_AP_STATE_CHANGED_ACTION =
 			"android.net.wifi.WIFI_AP_STATE_CHANGED";
 
-	private final TaskScheduler scheduler;
+	private final ScheduledExecutorService scheduler;
 	private final EventBus eventBus;
-	private final Executor eventExecutor;
 	private final Context appContext;
-	private final AtomicReference<Cancellable> connectivityCheck =
+	private final AtomicReference<Future<?>> connectivityCheck =
 			new AtomicReference<>();
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
 	private volatile BroadcastReceiver networkStateReceiver = null;
 
 	@Inject
-	AndroidNetworkManager(TaskScheduler scheduler, EventBus eventBus,
+	AndroidNetworkManager(@Scheduler ScheduledExecutorService scheduler,
-			@EventExecutor Executor eventExecutor, Application app) {
+			EventBus eventBus, Application app) {
 		this.scheduler = scheduler;
 		this.eventBus = eventBus;
-		this.eventExecutor = eventExecutor;
 		this.appContext = app.getApplicationContext();
 	}
 
@@ -107,12 +104,11 @@ class AndroidNetworkManager implements NetworkManager, Service {
 	}
 
 	private void scheduleConnectionStatusUpdate(int delay, TimeUnit unit) {
-		Cancellable newConnectivityCheck =
+		Future<?> newConnectivityCheck =
-				scheduler.schedule(this::updateConnectionStatus, eventExecutor,
+				scheduler.schedule(this::updateConnectionStatus, delay, unit);
-						delay, unit);
+		Future<?> oldConnectivityCheck =
-		Cancellable oldConnectivityCheck =
 				connectivityCheck.getAndSet(newConnectivityCheck);
-		if (oldConnectivityCheck != null) oldConnectivityCheck.cancel();
+		if (oldConnectivityCheck != null) oldConnectivityCheck.cancel(false);
 	}
 
 	private class NetworkStateReceiver extends BroadcastReceiver {

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothConnectionFactory.java

@@ -1,36 +0,0 @@
-package org.briarproject.bramble.plugin.bluetooth;
-
-import android.bluetooth.BluetoothSocket;
-
-import org.briarproject.bramble.api.io.TimeoutMonitor;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
-import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-import org.briarproject.bramble.api.system.AndroidWakeLockManager;
-
-import java.io.IOException;
-
-@NotNullByDefault
-class AndroidBluetoothConnectionFactory
-		implements BluetoothConnectionFactory<BluetoothSocket> {
-
-	private final BluetoothConnectionLimiter connectionLimiter;
-	private final AndroidWakeLockManager wakeLockManager;
-	private final TimeoutMonitor timeoutMonitor;
-
-	AndroidBluetoothConnectionFactory(
-			BluetoothConnectionLimiter connectionLimiter,
-			AndroidWakeLockManager wakeLockManager,
-			TimeoutMonitor timeoutMonitor) {
-		this.connectionLimiter = connectionLimiter;
-		this.wakeLockManager = wakeLockManager;
-		this.timeoutMonitor = timeoutMonitor;
-	}
-
-	@Override
-	public DuplexTransportConnection wrapSocket(DuplexPlugin plugin,
-			BluetoothSocket s) throws IOException {
-		return new AndroidBluetoothTransportConnection(plugin,
-				connectionLimiter, wakeLockManager, timeoutMonitor, s);
-	}
-}

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPlugin.java

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.plugin.bluetooth;
 
-import android.app.Application;
 import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.BluetoothDevice;
 import android.bluetooth.BluetoothServerSocket;
@@ -10,9 +9,9 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.PluginException;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
@@ -31,6 +30,7 @@ import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
 import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
@@ -59,40 +59,35 @@ import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class AndroidBluetoothPlugin
+class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
-		extends BluetoothPlugin<BluetoothSocket, BluetoothServerSocket> {
 
 	private static final Logger LOG =
 			getLogger(AndroidBluetoothPlugin.class.getName());
 
 	private static final int MAX_DISCOVERY_MS = 10_000;
 
+	private final ScheduledExecutorService scheduler;
 	private final AndroidExecutor androidExecutor;
-	private final Application app;
+	private final Context appContext;
 	private final Clock clock;
 
+	private volatile boolean wasEnabledByUs = false;
 	private volatile BluetoothStateReceiver receiver = null;
 
 	// Non-null if the plugin started successfully
 	private volatile BluetoothAdapter adapter = null;
 
 	AndroidBluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
-			BluetoothConnectionFactory<BluetoothSocket> connectionFactory,
+			TimeoutMonitor timeoutMonitor, Executor ioExecutor,
-			Executor ioExecutor,
+			SecureRandom secureRandom, ScheduledExecutorService scheduler,
-			Executor wakefulIoExecutor,
+			AndroidExecutor androidExecutor, Context appContext, Clock clock,
-			SecureRandom secureRandom,
+			PluginCallback callback, int maxLatency, int maxIdleTime,
-			AndroidExecutor androidExecutor,
+			int pollingInterval) {
-			Application app,
+		super(connectionLimiter, timeoutMonitor, ioExecutor, secureRandom,
-			Clock clock,
+				callback, maxLatency, maxIdleTime, pollingInterval);
-			Backoff backoff,
+		this.scheduler = scheduler;
-			PluginCallback callback,
-			int maxLatency,
-			int maxIdleTime) {
-		super(connectionLimiter, connectionFactory, ioExecutor,
-				wakefulIoExecutor, secureRandom, backoff, callback,
-				maxLatency, maxIdleTime);
 		this.androidExecutor = androidExecutor;
-		this.app = app;
+		this.appContext = appContext;
 		this.clock = clock;
 	}
 
@@ -104,13 +99,13 @@ class AndroidBluetoothPlugin
 		filter.addAction(ACTION_STATE_CHANGED);
 		filter.addAction(ACTION_SCAN_MODE_CHANGED);
 		receiver = new BluetoothStateReceiver();
-		app.registerReceiver(receiver, filter);
+		appContext.registerReceiver(receiver, filter);
 	}
 
 	@Override
 	public void stop() {
 		super.stop();
-		if (receiver != null) app.unregisterReceiver(receiver);
+		if (receiver != null) appContext.unregisterReceiver(receiver);
 	}
 
 	@Override
@@ -132,11 +127,42 @@ class AndroidBluetoothPlugin
 		return adapter != null && adapter.isEnabled();
 	}
 
+	@Override
+	void enableAdapter() {
+		if (adapter != null && !adapter.isEnabled()) {
+			if (adapter.enable()) {
+				LOG.info("Enabling Bluetooth");
+				wasEnabledByUs = true;
+			} else {
+				LOG.info("Could not enable Bluetooth");
+			}
+		}
+	}
+
+	@Override
+	void disableAdapterIfEnabledByUs() {
+		if (isAdapterEnabled() && wasEnabledByUs) {
+			if (adapter.disable()) LOG.info("Disabling Bluetooth");
+			else LOG.info("Could not disable Bluetooth");
+			wasEnabledByUs = false;
+		}
+	}
+
+	@Override
+	void setEnabledByUs() {
+		wasEnabledByUs = true;
+	}
+
+	@Override
+	void onAdapterDisabled() {
+		super.onAdapterDisabled();
+		wasEnabledByUs = false;
+	}
+
 	@Override
 	@Nullable
 	String getBluetoothAddress() {
-		if (adapter == null) return null;
+		String address = AndroidUtils.getBluetoothAddress(appContext, adapter);
-		String address = AndroidUtils.getBluetoothAddress(app, adapter);
 		return address.isEmpty() ? null : address;
 	}
 
@@ -154,7 +180,13 @@ class AndroidBluetoothPlugin
 	@Override
 	DuplexTransportConnection acceptConnection(BluetoothServerSocket ss)
 			throws IOException {
-		return connectionFactory.wrapSocket(this, ss.accept());
+		return wrapSocket(ss.accept());
+	}
+
+	private DuplexTransportConnection wrapSocket(BluetoothSocket s)
+			throws IOException {
+		return new AndroidBluetoothTransportConnection(this, connectionLimiter,
+				timeoutMonitor, appContext, scheduler, s);
 	}
 
 	@Override
@@ -171,7 +203,7 @@ class AndroidBluetoothPlugin
 		try {
 			s = d.createInsecureRfcommSocketToServiceRecord(u);
 			s.connect();
-			return connectionFactory.wrapSocket(this, s);
+			return wrapSocket(s);
 		} catch (IOException e) {
 			IoUtils.tryToClose(s, LOG, WARNING);
 			throw e;
@@ -206,7 +238,7 @@ class AndroidBluetoothPlugin
 		filter.addAction(ACTION_DISCOVERY_STARTED);
 		filter.addAction(ACTION_DISCOVERY_FINISHED);
 		filter.addAction(ACTION_FOUND);
-		app.registerReceiver(receiver, filter);
+		appContext.registerReceiver(receiver, filter);
 		try {
 			if (adapter.startDiscovery()) {
 				long now = clock.currentTimeMillis();
@@ -243,7 +275,7 @@ class AndroidBluetoothPlugin
 		} finally {
 			LOG.info("Cancelling discovery");
 			adapter.cancelDiscovery();
-			app.unregisterReceiver(receiver);
+			appContext.unregisterReceiver(receiver);
 		}
 		// Shuffle the addresses so we don't always try the same one first
 		shuffle(addresses);

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPluginFactory.java

@@ -1,72 +1,57 @@
 package org.briarproject.bramble.plugin.bluetooth;
 
-import android.app.Application;
+import android.content.Context;
-import android.bluetooth.BluetoothSocket;
 
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.io.TimeoutMonitor;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.plugin.BackoffFactory;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.system.AndroidExecutor;
-import org.briarproject.bramble.api.system.AndroidWakeLockManager;
 import org.briarproject.bramble.api.system.Clock;
-import org.briarproject.bramble.api.system.WakefulIoExecutor;
 
 import java.security.SecureRandom;
 import java.util.concurrent.Executor;
+import java.util.concurrent.ScheduledExecutorService;
 
 import javax.annotation.concurrent.Immutable;
-import javax.inject.Inject;
 
+import static java.util.concurrent.TimeUnit.MINUTES;
+import static java.util.concurrent.TimeUnit.SECONDS;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
 
 @Immutable
 @NotNullByDefault
 public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 
-	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
+	private static final int MAX_LATENCY = (int) SECONDS.toMillis(30);
-	private static final int MAX_IDLE_TIME = 30 * 1000; // 30 seconds
+	private static final int MAX_IDLE_TIME = (int) SECONDS.toMillis(30);
-	private static final int MIN_POLLING_INTERVAL = 60 * 1000; // 1 minute
+	private static final int POLLING_INTERVAL = (int) MINUTES.toMillis(2);
-	private static final int MAX_POLLING_INTERVAL = 10 * 60 * 1000; // 10 mins
-	private static final double BACKOFF_BASE = 1.2;
 
-	private final Executor ioExecutor, wakefulIoExecutor;
+	private final Executor ioExecutor;
+	private final ScheduledExecutorService scheduler;
 	private final AndroidExecutor androidExecutor;
-	private final AndroidWakeLockManager wakeLockManager;
+	private final Context appContext;
-	private final Application app;
 	private final SecureRandom secureRandom;
 	private final EventBus eventBus;
 	private final Clock clock;
 	private final TimeoutMonitor timeoutMonitor;
-	private final BackoffFactory backoffFactory;
 
-	@Inject
+	public AndroidBluetoothPluginFactory(Executor ioExecutor,
-	public AndroidBluetoothPluginFactory(@IoExecutor Executor ioExecutor,
+			ScheduledExecutorService scheduler,
-			@WakefulIoExecutor Executor wakefulIoExecutor,
+			AndroidExecutor androidExecutor, Context appContext,
-			AndroidExecutor androidExecutor,
+			SecureRandom secureRandom, EventBus eventBus, Clock clock,
-			AndroidWakeLockManager wakeLockManager,
+			TimeoutMonitor timeoutMonitor) {
-			Application app,
-			SecureRandom secureRandom,
-			EventBus eventBus,
-			Clock clock,
-			TimeoutMonitor timeoutMonitor,
-			BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
-		this.wakefulIoExecutor = wakefulIoExecutor;
+		this.scheduler = scheduler;
 		this.androidExecutor = androidExecutor;
-		this.wakeLockManager = wakeLockManager;
+		this.appContext = appContext;
-		this.app = app;
 		this.secureRandom = secureRandom;
 		this.eventBus = eventBus;
 		this.clock = clock;
 		this.timeoutMonitor = timeoutMonitor;
-		this.backoffFactory = backoffFactory;
 	}
 
 	@Override
@@ -83,15 +68,10 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 	public DuplexPlugin createPlugin(PluginCallback callback) {
 		BluetoothConnectionLimiter connectionLimiter =
 				new BluetoothConnectionLimiterImpl(eventBus);
-		BluetoothConnectionFactory<BluetoothSocket> connectionFactory =
-				new AndroidBluetoothConnectionFactory(connectionLimiter,
-						wakeLockManager, timeoutMonitor);
-		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
-				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidBluetoothPlugin plugin = new AndroidBluetoothPlugin(
-				connectionLimiter, connectionFactory, ioExecutor,
+				connectionLimiter, timeoutMonitor, ioExecutor, secureRandom,
-				wakefulIoExecutor, secureRandom, androidExecutor, app,
+				scheduler, androidExecutor, appContext, clock, callback,
-				clock, backoff, callback, MAX_LATENCY, MAX_IDLE_TIME);
+				MAX_LATENCY, MAX_IDLE_TIME, POLLING_INTERVAL);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothTransportConnection.java

@@ -1,19 +1,26 @@
 package org.briarproject.bramble.plugin.bluetooth;
 
 import android.bluetooth.BluetoothSocket;
+import android.content.Context;
+import android.os.PowerManager;
 
 import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.duplex.AbstractDuplexTransportConnection;
-import org.briarproject.bramble.api.system.AndroidWakeLock;
+import org.briarproject.bramble.util.RenewableWakeLock;
-import org.briarproject.bramble.api.system.AndroidWakeLockManager;
 
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.util.concurrent.ScheduledExecutorService;
 
+import static android.content.Context.POWER_SERVICE;
+import static android.os.PowerManager.PARTIAL_WAKE_LOCK;
+import static java.util.concurrent.TimeUnit.MINUTES;
+import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_ADDRESS;
+import static org.briarproject.bramble.util.AndroidUtils.getWakeLockTag;
 import static org.briarproject.bramble.util.AndroidUtils.isValidBluetoothAddress;
 
 @NotNullByDefault
@@ -21,21 +28,25 @@ class AndroidBluetoothTransportConnection
 		extends AbstractDuplexTransportConnection {
 
 	private final BluetoothConnectionLimiter connectionLimiter;
+	private final RenewableWakeLock wakeLock;
 	private final BluetoothSocket socket;
 	private final InputStream in;
-	private final AndroidWakeLock wakeLock;
 
 	AndroidBluetoothTransportConnection(Plugin plugin,
 			BluetoothConnectionLimiter connectionLimiter,
-			AndroidWakeLockManager wakeLockManager,
+			TimeoutMonitor timeoutMonitor, Context appContext,
-			TimeoutMonitor timeoutMonitor,
+			ScheduledExecutorService scheduler, BluetoothSocket socket)
-			BluetoothSocket socket) throws IOException {
+			throws IOException {
 		super(plugin);
 		this.connectionLimiter = connectionLimiter;
 		this.socket = socket;
 		in = timeoutMonitor.createTimeoutInputStream(
 				socket.getInputStream(), plugin.getMaxIdleTime() * 2);
-		wakeLock = wakeLockManager.createWakeLock("BluetoothConnection");
+		PowerManager powerManager = (PowerManager)
+				requireNonNull(appContext.getSystemService(POWER_SERVICE));
+		String tag = getWakeLockTag(appContext);
+		wakeLock = new RenewableWakeLock(powerManager, scheduler,
+				PARTIAL_WAKE_LOCK, tag, 1, MINUTES);
 		wakeLock.acquire();
 		String address = socket.getRemoteDevice().getAddress();
 		if (isValidBluetoothAddress(address)) remote.put(PROP_ADDRESS, address);
@@ -55,7 +66,6 @@ class AndroidBluetoothTransportConnection
 	protected void closeConnection(boolean exception) throws IOException {
 		try {
 			socket.close();
-			in.close();
 		} finally {
 			wakeLock.release();
 			connectionLimiter.connectionClosed(this);

bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPlugin.java

@@ -1,7 +1,7 @@
 package org.briarproject.bramble.plugin.tcp;
 
 import android.annotation.TargetApi;
-import android.app.Application;
+import android.content.Context;
 import android.net.ConnectivityManager;
 import android.net.LinkAddress;
 import android.net.LinkProperties;
@@ -15,7 +15,6 @@ import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.settings.Settings;
 
@@ -42,7 +41,6 @@ import static java.util.Collections.list;
 import static java.util.Collections.singletonList;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.DEFAULT_PREF_PLUGIN_ENABLE;
 import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
 import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
@@ -62,22 +60,20 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 
 	private volatile SocketFactory socketFactory;
 
-	AndroidLanTcpPlugin(Executor ioExecutor,
+	AndroidLanTcpPlugin(Executor ioExecutor, Context appContext,
-			Executor wakefulIoExecutor,
+			PluginCallback callback, int maxLatency, int maxIdleTime,
-			Application app,
+			int pollingInterval, int connectionTimeout) {
-			Backoff backoff,
+		super(ioExecutor, callback, maxLatency, maxIdleTime, pollingInterval,
-			PluginCallback callback,
+				connectionTimeout);
-			int maxLatency,
-			int maxIdleTime,
-			int connectionTimeout) {
-		super(ioExecutor, wakefulIoExecutor, backoff, callback, maxLatency,
-				maxIdleTime, connectionTimeout);
 		// Don't execute more than one connection status check at a time
 		connectionStatusExecutor =
 				new PoliteExecutor("AndroidLanTcpPlugin", ioExecutor, 1);
-		connectivityManager = (ConnectivityManager)
+		ConnectivityManager connectivityManager = (ConnectivityManager)
-				requireNonNull(app.getSystemService(CONNECTIVITY_SERVICE));
+				appContext.getSystemService(CONNECTIVITY_SERVICE);
-		wifiManager = (WifiManager) app.getSystemService(WIFI_SERVICE);
+		if (connectivityManager == null) throw new AssertionError();
+		this.connectivityManager = connectivityManager;
+		wifiManager = (WifiManager) appContext.getApplicationContext()
+				.getSystemService(WIFI_SERVICE);
 		socketFactory = SocketFactory.getDefault();
 	}
 
@@ -277,11 +273,11 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 				// make outgoing connections on API 21+ if another network
 				// has internet access
 				socketFactory = SocketFactory.getDefault();
-				bind();
+				if (s == INACTIVE) bind();
 			} else {
 				LOG.info("Connected to wifi");
 				socketFactory = getSocketFactory();
-				bind();
+				if (s == INACTIVE) bind();
 			}
 		});
 	}

bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPluginFactory.java

@@ -1,52 +1,40 @@
 package org.briarproject.bramble.plugin.tcp;
 
-import android.app.Application;
+import android.content.Context;
 
 import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.plugin.BackoffFactory;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
-import org.briarproject.bramble.api.system.WakefulIoExecutor;
 
 import java.util.concurrent.Executor;
 
 import javax.annotation.concurrent.Immutable;
-import javax.inject.Inject;
 
+import static java.util.concurrent.TimeUnit.MINUTES;
+import static java.util.concurrent.TimeUnit.SECONDS;
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.ID;
 
 @Immutable
 @NotNullByDefault
 public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 
-	private static final int MAX_LATENCY = 30_000; // 30 seconds
+	private static final int MAX_LATENCY = (int) SECONDS.toMillis(30);
-	private static final int MAX_IDLE_TIME = 30_000; // 30 seconds
+	private static final int MAX_IDLE_TIME = (int) SECONDS.toMillis(30);
-	private static final int CONNECTION_TIMEOUT = 3_000; // 3 seconds
+	private static final int POLLING_INTERVAL = (int) MINUTES.toMillis(1);
-	private static final int MIN_POLLING_INTERVAL = 60_000; // 1 minute
+	private static final int CONNECTION_TIMEOUT = (int) SECONDS.toMillis(3);
-	private static final int MAX_POLLING_INTERVAL = 600_000; // 10 mins
-	private static final double BACKOFF_BASE = 1.2;
 
-	private final Executor ioExecutor, wakefulIoExecutor;
+	private final Executor ioExecutor;
 	private final EventBus eventBus;
-	private final BackoffFactory backoffFactory;
+	private final Context appContext;
-	private final Application app;
 
-	@Inject
+	public AndroidLanTcpPluginFactory(Executor ioExecutor, EventBus eventBus,
-	public AndroidLanTcpPluginFactory(@IoExecutor Executor ioExecutor,
+			Context appContext) {
-			@WakefulIoExecutor Executor wakefulIoExecutor,
-			EventBus eventBus,
-			BackoffFactory backoffFactory,
-			Application app) {
 		this.ioExecutor = ioExecutor;
-		this.wakefulIoExecutor = wakefulIoExecutor;
 		this.eventBus = eventBus;
-		this.backoffFactory = backoffFactory;
+		this.appContext = appContext;
-		this.app = app;
 	}
 
 	@Override
@@ -61,11 +49,9 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 
 	@Override
 	public DuplexPlugin createPlugin(PluginCallback callback) {
-		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
-				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidLanTcpPlugin plugin = new AndroidLanTcpPlugin(ioExecutor,
-				wakefulIoExecutor, app, backoff, callback,
+				appContext, callback, MAX_LATENCY, MAX_IDLE_TIME,
-				MAX_LATENCY, MAX_IDLE_TIME, CONNECTION_TIMEOUT);
+				POLLING_INTERVAL, CONNECTION_TIMEOUT);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -1,86 +1,61 @@
 package org.briarproject.bramble.plugin.tor;
 
-import android.app.Application;
+import android.content.Context;
 import android.content.pm.PackageInfo;
 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;
-import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.PluginCallback;
-import org.briarproject.bramble.api.system.AndroidWakeLock;
-import org.briarproject.bramble.api.system.AndroidWakeLockManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
-import org.briarproject.bramble.util.AndroidUtils;
+import org.briarproject.bramble.util.RenewableWakeLock;
 
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
 import java.io.IOException;
-import java.util.ArrayList;
-import java.util.List;
 import java.util.concurrent.Executor;
-import java.util.logging.Logger;
+import java.util.concurrent.ScheduledExecutorService;
-import java.util.zip.ZipEntry;
-import java.util.zip.ZipInputStream;
 
 import javax.net.SocketFactory;
 
-import static android.os.Build.VERSION.SDK_INT;
+import static android.content.Context.MODE_PRIVATE;
-import static java.util.Arrays.asList;
+import static android.content.Context.POWER_SERVICE;
-import static java.util.logging.Level.INFO;
+import static android.os.PowerManager.PARTIAL_WAKE_LOCK;
-import static java.util.logging.Logger.getLogger;
+import static java.util.concurrent.TimeUnit.MINUTES;
+import static org.briarproject.bramble.util.AndroidUtils.getWakeLockTag;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 class AndroidTorPlugin extends TorPlugin {
 
-	private static final List<String> LIBRARY_ARCHITECTURES =
+	private final Context appContext;
-			asList("armeabi-v7a", "arm64-v8a", "x86", "x86_64");
+	private final RenewableWakeLock wakeLock;
 
-	private static final String TOR_LIB_NAME = "libtor.so";
+	AndroidTorPlugin(Executor ioExecutor, ScheduledExecutorService scheduler,
-	private static final String OBFS4_LIB_NAME = "libobfs4proxy.so";
+			Context appContext, NetworkManager networkManager,
-
+			LocationUtils locationUtils, SocketFactory torSocketFactory,
-	private static final Logger LOG =
+			Clock clock, ResourceProvider resourceProvider,
-			getLogger(AndroidTorPlugin.class.getName());
-
-	private final Application app;
-	private final AndroidWakeLock wakeLock;
-	private final File torLib, obfs4Lib;
-
-	AndroidTorPlugin(Executor ioExecutor,
-			Executor wakefulIoExecutor,
-			Application app,
-			NetworkManager networkManager,
-			LocationUtils locationUtils,
-			SocketFactory torSocketFactory,
-			Clock clock,
-			ResourceProvider resourceProvider,
 			CircumventionProvider circumventionProvider,
 			BatteryManager batteryManager,
-			AndroidWakeLockManager wakeLockManager,
-			Backoff backoff,
 			TorRendezvousCrypto torRendezvousCrypto,
-			PluginCallback callback,
+			PluginCallback callback, String architecture, int maxLatency,
-			String architecture,
+			int maxIdleTime, int initialPollingInterval,
-			int maxLatency,
+			int stablePollingInterval) {
-			int maxIdleTime,
+		super(ioExecutor, networkManager, locationUtils, torSocketFactory,
-			File torDirectory) {
+				clock, resourceProvider, circumventionProvider, batteryManager,
-		super(ioExecutor, wakefulIoExecutor, networkManager, locationUtils,
-				torSocketFactory, clock, resourceProvider,
-				circumventionProvider, batteryManager, backoff,
 				torRendezvousCrypto, callback, architecture, maxLatency,
-				maxIdleTime, torDirectory);
+				maxIdleTime, initialPollingInterval, stablePollingInterval,
-		this.app = app;
+				appContext.getDir("tor", MODE_PRIVATE));
-		wakeLock = wakeLockManager.createWakeLock("TorPlugin");
+		this.appContext = appContext;
-		String nativeLibDir = app.getApplicationInfo().nativeLibraryDir;
+		PowerManager pm = (PowerManager)
-		torLib = new File(nativeLibDir, TOR_LIB_NAME);
+				appContext.getSystemService(POWER_SERVICE);
-		obfs4Lib = new File(nativeLibDir, OBFS4_LIB_NAME);
+		if (pm == null) throw new AssertionError();
+		wakeLock = new RenewableWakeLock(pm, scheduler, PARTIAL_WAKE_LOCK,
+				getWakeLockTag(appContext), 1, MINUTES);
 	}
 
 	@Override
@@ -91,8 +66,8 @@ class AndroidTorPlugin extends TorPlugin {
 	@Override
 	protected long getLastUpdateTime() {
 		try {
-			PackageManager pm = app.getPackageManager();
+			PackageManager pm = appContext.getPackageManager();
-			PackageInfo pi = pm.getPackageInfo(app.getPackageName(), 0);
+			PackageInfo pi = pm.getPackageInfo(appContext.getPackageName(), 0);
 			return pi.lastUpdateTime;
 		} catch (NameNotFoundException e) {
 			throw new AssertionError(e);
@@ -111,112 +86,4 @@ class AndroidTorPlugin extends TorPlugin {
 		super.stop();
 		wakeLock.release();
 	}
-
-	@Override
-	protected File getTorExecutableFile() {
-		return torLib.exists() ? torLib : super.getTorExecutableFile();
-	}
-
-	@Override
-	protected File getObfs4ExecutableFile() {
-		return obfs4Lib.exists() ? obfs4Lib : super.getObfs4ExecutableFile();
-	}
-
-	@Override
-	protected void installTorExecutable() throws IOException {
-		File extracted = super.getTorExecutableFile();
-		if (torLib.exists()) {
-			// If an older version left behind a Tor binary, delete it
-			if (extracted.exists()) {
-				if (extracted.delete()) LOG.info("Deleted Tor binary");
-				else LOG.info("Failed to delete Tor binary");
-			}
-		} else if (SDK_INT < 29) {
-			// The binary wasn't extracted at install time. Try to extract it
-			extractLibraryFromApk(TOR_LIB_NAME, extracted);
-		} else {
-			// No point extracting the binary, we won't be allowed to execute it
-			throw new FileNotFoundException(torLib.getAbsolutePath());
-		}
-	}
-
-	@Override
-	protected void installObfs4Executable() throws IOException {
-		File extracted = super.getObfs4ExecutableFile();
-		if (obfs4Lib.exists()) {
-			// If an older version left behind an obfs4 binary, delete it
-			if (extracted.exists()) {
-				if (extracted.delete()) LOG.info("Deleted obfs4 binary");
-				else LOG.info("Failed to delete obfs4 binary");
-			}
-		} else if (SDK_INT < 29) {
-			// The binary wasn't extracted at install time. Try to extract it
-			extractLibraryFromApk(OBFS4_LIB_NAME, extracted);
-		} else {
-			// No point extracting the binary, we won't be allowed to execute it
-			throw new FileNotFoundException(obfs4Lib.getAbsolutePath());
-		}
-	}
-
-	private void extractLibraryFromApk(String libName, File dest)
-			throws IOException {
-		File sourceDir = new File(app.getApplicationInfo().sourceDir);
-		if (sourceDir.isFile()) {
-			// Look for other APK files in the same directory, if we're allowed
-			File parent = sourceDir.getParentFile();
-			if (parent != null) sourceDir = parent;
-		}
-		List<String> libPaths = getSupportedLibraryPaths(libName);
-		for (File apk : findApkFiles(sourceDir)) {
-			ZipInputStream zin = new ZipInputStream(new FileInputStream(apk));
-			for (ZipEntry e = zin.getNextEntry(); e != null;
-					e = zin.getNextEntry()) {
-				if (libPaths.contains(e.getName())) {
-					if (LOG.isLoggable(INFO)) {
-						LOG.info("Extracting " + e.getName()
-								+ " from " + apk.getAbsolutePath());
-					}
-					extract(zin, dest); // Zip input stream will be closed
-					return;
-				}
-			}
-			zin.close();
-		}
-		throw new FileNotFoundException(libName);
-	}
-
-	/**
-	 * Returns all files with the extension .apk or .APK under the given root.
-	 */
-	private List<File> findApkFiles(File root) {
-		List<File> files = new ArrayList<>();
-		findApkFiles(root, files);
-		return files;
-	}
-
-	private void findApkFiles(File f, List<File> files) {
-		if (f.isFile() && f.getName().toLowerCase().endsWith(".apk")) {
-			files.add(f);
-		} else if (f.isDirectory()) {
-			File[] children = f.listFiles();
-			if (children != null) {
-				for (File child : children) findApkFiles(child, files);
-			}
-		}
-	}
-
-	/**
-	 * Returns the paths at which libraries with the given name would be found
-	 * inside an APK file, for all architectures supported by the device, in
-	 * order of preference.
-	 */
-	private List<String> getSupportedLibraryPaths(String libName) {
-		List<String> architectures = new ArrayList<>();
-		for (String abi : AndroidUtils.getSupportedArchitectures()) {
-			if (LIBRARY_ARCHITECTURES.contains(abi)) {
-				architectures.add("lib/" + abi + "/" + libName);
-			}
-		}
-		return architectures;
-	}
 }

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

@@ -1,91 +1,86 @@
 package org.briarproject.bramble.plugin.tor;
 
-import android.app.Application;
+import android.content.Context;
 
 import org.briarproject.bramble.api.battery.BatteryManager;
 import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.plugin.BackoffFactory;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TorConstants;
-import org.briarproject.bramble.api.plugin.TorDirectory;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
-import org.briarproject.bramble.api.system.AndroidWakeLockManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
-import org.briarproject.bramble.api.system.WakefulIoExecutor;
 import org.briarproject.bramble.util.AndroidUtils;
 
-import java.io.File;
 import java.util.concurrent.Executor;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.logging.Logger;
 
 import javax.annotation.concurrent.Immutable;
-import javax.inject.Inject;
 import javax.net.SocketFactory;
 
+import static java.util.concurrent.TimeUnit.MINUTES;
+import static java.util.concurrent.TimeUnit.SECONDS;
+import static java.util.logging.Logger.getLogger;
+
 @Immutable
 @NotNullByDefault
 public class AndroidTorPluginFactory implements DuplexPluginFactory {
 
 	private static final Logger LOG =
-			Logger.getLogger(AndroidTorPluginFactory.class.getName());
+			getLogger(AndroidTorPluginFactory.class.getName());
 
-	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
+	private static final int MAX_LATENCY = (int) SECONDS.toMillis(30);
-	private static final int MAX_IDLE_TIME = 30 * 1000; // 30 seconds
+	private static final int MAX_IDLE_TIME = (int) SECONDS.toMillis(30);
-	private static final int MIN_POLLING_INTERVAL = 60 * 1000; // 1 minute
-	private static final int MAX_POLLING_INTERVAL = 10 * 60 * 1000; // 10 mins
-	private static final double BACKOFF_BASE = 1.2;
 
-	private final Executor ioExecutor, wakefulIoExecutor;
+	/**
-	private final Application app;
+	 * How often to poll before our hidden service becomes reachable.
+	 */
+	private static final int INITIAL_POLLING_INTERVAL =
+			(int) MINUTES.toMillis(1);
+
+	/**
+	 * How often to poll when our hidden service is reachable. Our contacts
+	 * will poll when they come online, so our polling is just a fallback in
+	 * case of repeated connection failures.
+	 */
+	private static final int STABLE_POLLING_INTERVAL =
+			(int) MINUTES.toMillis(15);
+
+	private final Executor ioExecutor;
+	private final ScheduledExecutorService scheduler;
+	private final Context appContext;
 	private final NetworkManager networkManager;
 	private final LocationUtils locationUtils;
 	private final EventBus eventBus;
 	private final SocketFactory torSocketFactory;
-	private final BackoffFactory backoffFactory;
 	private final ResourceProvider resourceProvider;
 	private final CircumventionProvider circumventionProvider;
 	private final BatteryManager batteryManager;
-	private final AndroidWakeLockManager wakeLockManager;
 	private final Clock clock;
-	private final File torDirectory;
 
-	@Inject
+	public AndroidTorPluginFactory(Executor ioExecutor,
-	public AndroidTorPluginFactory(@IoExecutor Executor ioExecutor,
+			ScheduledExecutorService scheduler, Context appContext,
-			@WakefulIoExecutor Executor wakefulIoExecutor,
+			NetworkManager networkManager, LocationUtils locationUtils,
-			Application app,
+			EventBus eventBus, SocketFactory torSocketFactory,
-			NetworkManager networkManager,
-			LocationUtils locationUtils,
-			EventBus eventBus,
-			SocketFactory torSocketFactory,
-			BackoffFactory backoffFactory,
 			ResourceProvider resourceProvider,
 			CircumventionProvider circumventionProvider,
-			BatteryManager batteryManager,
+			BatteryManager batteryManager, Clock clock) {
-			AndroidWakeLockManager wakeLockManager,
-			Clock clock,
-			@TorDirectory File torDirectory) {
 		this.ioExecutor = ioExecutor;
-		this.wakefulIoExecutor = wakefulIoExecutor;
+		this.scheduler = scheduler;
-		this.app = app;
+		this.appContext = appContext;
 		this.networkManager = networkManager;
 		this.locationUtils = locationUtils;
 		this.eventBus = eventBus;
 		this.torSocketFactory = torSocketFactory;
-		this.backoffFactory = backoffFactory;
 		this.resourceProvider = resourceProvider;
 		this.circumventionProvider = circumventionProvider;
 		this.batteryManager = batteryManager;
-		this.wakeLockManager = wakeLockManager;
 		this.clock = clock;
-		this.torDirectory = torDirectory;
 	}
 
 	@Override
@@ -125,15 +120,13 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 		// Use position-independent executable
 		architecture += "_pie";
 
-		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
-				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		TorRendezvousCrypto torRendezvousCrypto = new TorRendezvousCryptoImpl();
-		AndroidTorPlugin plugin = new AndroidTorPlugin(ioExecutor,
+		AndroidTorPlugin plugin = new AndroidTorPlugin(ioExecutor, scheduler,
-				wakefulIoExecutor, app, networkManager, locationUtils,
+				appContext, networkManager, locationUtils, torSocketFactory,
-				torSocketFactory, clock, resourceProvider,
+				clock, resourceProvider, circumventionProvider, batteryManager,
-				circumventionProvider, batteryManager, wakeLockManager,
+				torRendezvousCrypto, callback, architecture, MAX_LATENCY,
-				backoff, torRendezvousCrypto, callback, architecture,
+				MAX_IDLE_TIME, INITIAL_POLLING_INTERVAL,
-				MAX_LATENCY, MAX_IDLE_TIME, torDirectory);
+				STABLE_POLLING_INTERVAL);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

bramble-android/src/main/java/org/briarproject/bramble/system/AlarmConstants.java

@@ -1,18 +0,0 @@
-package org.briarproject.bramble.system;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-@NotNullByDefault
-interface AlarmConstants {
-
-	/**
-	 * Request code for the broadcast intent attached to the periodic alarm.
-	 */
-	int REQUEST_ALARM = 1;
-
-	/**
-	 * Key for storing the process ID in the extras of the periodic alarm's
-	 * intent. This allows us to ignore alarms scheduled by dead processes.
-	 */
-	String EXTRA_PID = "org.briarproject.bramble.EXTRA_PID";
-}

bramble-android/src/main/java/org/briarproject/bramble/system/AlarmReceiver.java

@@ -1,17 +0,0 @@
-package org.briarproject.bramble.system;
-
-import android.content.BroadcastReceiver;
-import android.content.Context;
-import android.content.Intent;
-
-import org.briarproject.bramble.BrambleApplication;
-
-public class AlarmReceiver extends BroadcastReceiver {
-
-	@Override
-	public void onReceive(Context ctx, Intent intent) {
-		BrambleApplication app =
-				(BrambleApplication) ctx.getApplicationContext();
-		app.getBrambleAppComponent().alarmListener().onAlarm(intent);
-	}
-}

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidSystemModule.java

@@ -1,17 +1,12 @@
 package org.briarproject.bramble.system;
 
 import org.briarproject.bramble.api.event.EventExecutor;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.system.AndroidExecutor;
-import org.briarproject.bramble.api.system.AndroidWakeLockManager;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
 import org.briarproject.bramble.api.system.SecureRandomProvider;
 
 import java.util.concurrent.Executor;
-import java.util.concurrent.RejectedExecutionHandler;
-import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.ScheduledThreadPoolExecutor;
 
 import javax.inject.Singleton;
 
@@ -21,23 +16,6 @@ import dagger.Provides;
 @Module
 public class AndroidSystemModule {
 
-	private final ScheduledExecutorService scheduledExecutorService;
-
-	public AndroidSystemModule() {
-		// Discard tasks that are submitted during shutdown
-		RejectedExecutionHandler policy =
-				new ScheduledThreadPoolExecutor.DiscardPolicy();
-		scheduledExecutorService = new ScheduledThreadPoolExecutor(1, policy);
-	}
-
-	@Provides
-	@Singleton
-	ScheduledExecutorService provideScheduledExecutorService(
-			LifecycleManager lifecycleManager) {
-		lifecycleManager.registerForShutdown(scheduledExecutorService);
-		return scheduledExecutorService;
-	}
-
 	@Provides
 	@Singleton
 	SecureRandomProvider provideSecureRandomProvider(
@@ -69,11 +47,4 @@ public class AndroidSystemModule {
 	ResourceProvider provideResourceProvider(AndroidResourceProvider provider) {
 		return provider;
 	}
-
-	@Provides
-	@Singleton
-	AndroidWakeLockManager provideWakeLockManager(
-			AndroidWakeLockManagerImpl wakeLockManager) {
-		return wakeLockManager;
-	}
 }

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidTaskScheduler.java

@@ -1,242 +0,0 @@
-package org.briarproject.bramble.system;
-
-import android.annotation.TargetApi;
-import android.app.AlarmManager;
-import android.app.Application;
-import android.app.PendingIntent;
-import android.content.Intent;
-import android.os.Process;
-import android.os.SystemClock;
-
-import org.briarproject.bramble.api.lifecycle.Service;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.system.AlarmListener;
-import org.briarproject.bramble.api.system.AndroidWakeLockManager;
-import org.briarproject.bramble.api.system.TaskScheduler;
-import org.briarproject.bramble.api.system.Wakeful;
-
-import java.util.ArrayList;
-import java.util.List;
-import java.util.PriorityQueue;
-import java.util.Queue;
-import java.util.concurrent.Executor;
-import java.util.concurrent.Future;
-import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.logging.Logger;
-
-import javax.annotation.concurrent.GuardedBy;
-import javax.annotation.concurrent.ThreadSafe;
-
-import static android.app.AlarmManager.ELAPSED_REALTIME_WAKEUP;
-import static android.app.AlarmManager.INTERVAL_FIFTEEN_MINUTES;
-import static android.app.PendingIntent.FLAG_CANCEL_CURRENT;
-import static android.content.Context.ALARM_SERVICE;
-import static android.os.Build.VERSION.SDK_INT;
-import static java.util.Objects.requireNonNull;
-import static java.util.concurrent.TimeUnit.MILLISECONDS;
-import static java.util.logging.Level.INFO;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.system.AlarmConstants.EXTRA_PID;
-import static org.briarproject.bramble.system.AlarmConstants.REQUEST_ALARM;
-
-@ThreadSafe
-@NotNullByDefault
-class AndroidTaskScheduler implements TaskScheduler, Service, AlarmListener {
-
-	private static final Logger LOG =
-			getLogger(AndroidTaskScheduler.class.getName());
-
-	private static final long ALARM_MS = INTERVAL_FIFTEEN_MINUTES;
-
-	private final Application app;
-	private final AndroidWakeLockManager wakeLockManager;
-	private final ScheduledExecutorService scheduledExecutorService;
-	private final AlarmManager alarmManager;
-
-	private final Object lock = new Object();
-	@GuardedBy("lock")
-	private final Queue<ScheduledTask> tasks = new PriorityQueue<>();
-
-	AndroidTaskScheduler(Application app,
-			AndroidWakeLockManager wakeLockManager,
-			ScheduledExecutorService scheduledExecutorService) {
-		this.app = app;
-		this.wakeLockManager = wakeLockManager;
-		this.scheduledExecutorService = scheduledExecutorService;
-		alarmManager = (AlarmManager)
-				requireNonNull(app.getSystemService(ALARM_SERVICE));
-	}
-
-	@Override
-	public void startService() {
-		scheduleAlarm();
-	}
-
-	@Override
-	public void stopService() {
-		cancelAlarm();
-	}
-
-	@Override
-	public Cancellable schedule(Runnable task, Executor executor, long delay,
-			TimeUnit unit) {
-		AtomicBoolean cancelled = new AtomicBoolean(false);
-		return schedule(task, executor, delay, unit, cancelled);
-	}
-
-	@Override
-	public Cancellable scheduleWithFixedDelay(Runnable task, Executor executor,
-			long delay, long interval, TimeUnit unit) {
-		AtomicBoolean cancelled = new AtomicBoolean(false);
-		return scheduleWithFixedDelay(task, executor, delay, interval, unit,
-				cancelled);
-	}
-
-	@Override
-	public void onAlarm(Intent intent) {
-		wakeLockManager.runWakefully(() -> {
-			int extraPid = intent.getIntExtra(EXTRA_PID, -1);
-			int currentPid = Process.myPid();
-			if (extraPid == currentPid) {
-				LOG.info("Alarm");
-				rescheduleAlarm();
-				runDueTasks();
-			} else if (LOG.isLoggable(INFO)) {
-				LOG.info("Ignoring alarm with PID " + extraPid
-						+ ", current PID is " + currentPid);
-			}
-		}, "TaskAlarm");
-	}
-
-	private Cancellable schedule(Runnable task, Executor executor, long delay,
-			TimeUnit unit, AtomicBoolean cancelled) {
-		long now = SystemClock.elapsedRealtime();
-		long dueMillis = now + MILLISECONDS.convert(delay, unit);
-		Runnable wakeful = () ->
-				wakeLockManager.executeWakefully(task, executor, "TaskHandoff");
-		Future<?> check = scheduleCheckForDueTasks(delay, unit);
-		ScheduledTask s = new ScheduledTask(wakeful, dueMillis, check,
-				cancelled);
-		synchronized (lock) {
-			tasks.add(s);
-		}
-		return s;
-	}
-
-	private Cancellable scheduleWithFixedDelay(Runnable task, Executor executor,
-			long delay, long interval, TimeUnit unit, AtomicBoolean cancelled) {
-		// All executions of this periodic task share a cancelled flag
-		Runnable wrapped = () -> {
-			task.run();
-			scheduleWithFixedDelay(task, executor, interval, interval, unit,
-					cancelled);
-		};
-		return schedule(wrapped, executor, delay, unit, cancelled);
-	}
-
-	private Future<?> scheduleCheckForDueTasks(long delay, TimeUnit unit) {
-		Runnable wakeful = () -> wakeLockManager.runWakefully(
-				this::runDueTasks, "TaskScheduler");
-		return scheduledExecutorService.schedule(wakeful, delay, unit);
-	}
-
-	@Wakeful
-	private void runDueTasks() {
-		long now = SystemClock.elapsedRealtime();
-		List<ScheduledTask> due = new ArrayList<>();
-		synchronized (lock) {
-			while (true) {
-				ScheduledTask s = tasks.peek();
-				if (s == null || s.dueMillis > now) break;
-				due.add(tasks.remove());
-			}
-		}
-		if (LOG.isLoggable(INFO)) {
-			LOG.info("Running " + due.size() + " due tasks");
-		}
-		for (ScheduledTask s : due) {
-			if (LOG.isLoggable(INFO)) {
-				LOG.info("Task is " + (now - s.dueMillis) + " ms overdue");
-			}
-			s.run();
-		}
-	}
-
-	private void scheduleAlarm() {
-		if (SDK_INT >= 23) scheduleIdleAlarm();
-		else scheduleInexactRepeatingAlarm();
-	}
-
-	private void rescheduleAlarm() {
-		// If SDK_INT < 23 the alarm repeats automatically
-		if (SDK_INT >= 23) scheduleIdleAlarm();
-	}
-
-	private void cancelAlarm() {
-		alarmManager.cancel(getAlarmPendingIntent());
-	}
-
-	private void scheduleInexactRepeatingAlarm() {
-		alarmManager.setInexactRepeating(ELAPSED_REALTIME_WAKEUP,
-				SystemClock.elapsedRealtime() + ALARM_MS, ALARM_MS,
-				getAlarmPendingIntent());
-	}
-
-	@TargetApi(23)
-	private void scheduleIdleAlarm() {
-		alarmManager.setAndAllowWhileIdle(ELAPSED_REALTIME_WAKEUP,
-				SystemClock.elapsedRealtime() + ALARM_MS,
-				getAlarmPendingIntent());
-	}
-
-	private PendingIntent getAlarmPendingIntent() {
-		Intent i = new Intent(app, AlarmReceiver.class);
-		i.putExtra(EXTRA_PID, android.os.Process.myPid());
-		return PendingIntent.getBroadcast(app, REQUEST_ALARM, i,
-				FLAG_CANCEL_CURRENT);
-	}
-
-	private class ScheduledTask
-			implements Runnable, Cancellable, Comparable<ScheduledTask> {
-
-		private final Runnable task;
-		private final long dueMillis;
-		private final Future<?> check;
-		private final AtomicBoolean cancelled;
-
-		public ScheduledTask(Runnable task, long dueMillis,
-				Future<?> check, AtomicBoolean cancelled) {
-			this.task = task;
-			this.dueMillis = dueMillis;
-			this.check = check;
-			this.cancelled = cancelled;
-		}
-
-		@Override
-		public void run() {
-			if (!cancelled.get()) task.run();
-		}
-
-		@Override
-		public void cancel() {
-			// Cancel any future executions of this task
-			cancelled.set(true);
-			// Cancel the scheduled check for due tasks
-			check.cancel(false);
-			// Remove the task from the queue
-			synchronized (lock) {
-				tasks.remove(this);
-			}
-		}
-
-		@Override
-		public int compareTo(ScheduledTask s) {
-			//noinspection UseCompareMethod
-			if (dueMillis < s.dueMillis) return -1;
-			if (dueMillis > s.dueMillis) return 1;
-			return 0;
-		}
-	}
-}

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidTaskSchedulerModule.java

@@ -1,49 +0,0 @@
-package org.briarproject.bramble.system;
-
-import android.app.Application;
-
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.system.AlarmListener;
-import org.briarproject.bramble.api.system.AndroidWakeLockManager;
-import org.briarproject.bramble.api.system.TaskScheduler;
-
-import java.util.concurrent.ScheduledExecutorService;
-
-import javax.inject.Inject;
-import javax.inject.Singleton;
-
-import dagger.Module;
-import dagger.Provides;
-
-@Module
-public class AndroidTaskSchedulerModule {
-
-	public static class EagerSingletons {
-		@Inject
-		AndroidTaskScheduler scheduler;
-	}
-
-	@Provides
-	@Singleton
-	AndroidTaskScheduler provideAndroidTaskScheduler(
-			LifecycleManager lifecycleManager, Application app,
-			AndroidWakeLockManager wakeLockManager,
-			ScheduledExecutorService scheduledExecutorService) {
-		AndroidTaskScheduler scheduler = new AndroidTaskScheduler(app,
-				wakeLockManager, scheduledExecutorService);
-		lifecycleManager.registerService(scheduler);
-		return scheduler;
-	}
-
-	@Provides
-	@Singleton
-	AlarmListener provideAlarmListener(AndroidTaskScheduler scheduler) {
-		return scheduler;
-	}
-
-	@Provides
-	@Singleton
-	TaskScheduler provideTaskScheduler(AndroidTaskScheduler scheduler) {
-		return scheduler;
-	}
-}

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidWakeLockImpl.java

@@ -1,74 +0,0 @@
-package org.briarproject.bramble.system;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.system.AndroidWakeLock;
-
-import java.util.concurrent.atomic.AtomicInteger;
-import java.util.logging.Logger;
-
-import javax.annotation.concurrent.GuardedBy;
-import javax.annotation.concurrent.ThreadSafe;
-
-import static java.util.logging.Level.FINE;
-import static java.util.logging.Logger.getLogger;
-
-/**
- * A wrapper around a {@link SharedWakeLock} that provides the more convenient
- * semantics of {@link AndroidWakeLock} (i.e. calls to acquire() and release()
- * don't need to be balanced).
- */
-@ThreadSafe
-@NotNullByDefault
-class AndroidWakeLockImpl implements AndroidWakeLock {
-
-	private static final Logger LOG =
-			getLogger(AndroidWakeLockImpl.class.getName());
-
-	private static final AtomicInteger INSTANCE_ID = new AtomicInteger(0);
-
-	private final SharedWakeLock sharedWakeLock;
-	private final String tag;
-
-	private final Object lock = new Object();
-	@GuardedBy("lock")
-	private boolean held = false;
-
-	AndroidWakeLockImpl(SharedWakeLock sharedWakeLock, String tag) {
-		this.sharedWakeLock = sharedWakeLock;
-		this.tag = tag + "_" + INSTANCE_ID.getAndIncrement();
-	}
-
-	@Override
-	public void acquire() {
-		synchronized (lock) {
-			if (held) {
-				if (LOG.isLoggable(FINE)) {
-					LOG.fine(tag + " already acquired");
-				}
-			} else {
-				if (LOG.isLoggable(FINE)) {
-					LOG.fine(tag + " acquiring shared wake lock");
-				}
-				held = true;
-				sharedWakeLock.acquire();
-			}
-		}
-	}
-
-	@Override
-	public void release() {
-		synchronized (lock) {
-			if (held) {
-				if (LOG.isLoggable(FINE)) {
-					LOG.fine(tag + " releasing shared wake lock");
-				}
-				held = false;
-				sharedWakeLock.release();
-			} else {
-				if (LOG.isLoggable(FINE)) {
-					LOG.fine(tag + " already released");
-				}
-			}
-		}
-	}
-}

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidWakeLockManagerImpl.java

@@ -1,119 +0,0 @@
-package org.briarproject.bramble.system;
-
-import android.app.Application;
-import android.content.Context;
-import android.content.pm.PackageInfo;
-import android.content.pm.PackageManager;
-import android.os.PowerManager;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.system.AndroidWakeLock;
-import org.briarproject.bramble.api.system.AndroidWakeLockManager;
-
-import java.util.concurrent.Executor;
-import java.util.concurrent.ScheduledExecutorService;
-
-import javax.inject.Inject;
-
-import static android.content.Context.POWER_SERVICE;
-import static android.os.PowerManager.PARTIAL_WAKE_LOCK;
-import static java.util.concurrent.TimeUnit.MINUTES;
-import static java.util.concurrent.TimeUnit.SECONDS;
-import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
-
-@NotNullByDefault
-class AndroidWakeLockManagerImpl implements AndroidWakeLockManager {
-
-	/**
-	 * How often to replace the wake lock.
-	 */
-	private static final long LOCK_DURATION_MS = MINUTES.toMillis(1);
-
-	/**
-	 * Automatically release the lock this many milliseconds after it's due
-	 * to have been replaced and released.
-	 */
-	private static final long SAFETY_MARGIN_MS = SECONDS.toMillis(30);
-
-	private final SharedWakeLock sharedWakeLock;
-
-	@Inject
-	AndroidWakeLockManagerImpl(Application app,
-			ScheduledExecutorService scheduledExecutorService) {
-		PowerManager powerManager = (PowerManager)
-				requireNonNull(app.getSystemService(POWER_SERVICE));
-		String tag = getWakeLockTag(app);
-		sharedWakeLock = new RenewableWakeLock(powerManager,
-				scheduledExecutorService, PARTIAL_WAKE_LOCK, tag,
-				LOCK_DURATION_MS, SAFETY_MARGIN_MS);
-	}
-
-	@Override
-	public AndroidWakeLock createWakeLock(String tag) {
-		return new AndroidWakeLockImpl(sharedWakeLock, tag);
-	}
-
-	@Override
-	public void runWakefully(Runnable r, String tag) {
-		AndroidWakeLock wakeLock = createWakeLock(tag);
-		wakeLock.acquire();
-		try {
-			r.run();
-		} finally {
-			wakeLock.release();
-		}
-	}
-
-	@Override
-	public void executeWakefully(Runnable r, Executor executor, String tag) {
-		AndroidWakeLock wakeLock = createWakeLock(tag);
-		wakeLock.acquire();
-		try {
-			executor.execute(() -> {
-				try {
-					r.run();
-				} finally {
-					// Release the wake lock if the task throws an exception
-					wakeLock.release();
-				}
-			});
-		} catch (Exception e) {
-			// Release the wake lock if the executor throws an exception when
-			// we submit the task (in which case the release() call above won't
-			// happen)
-			wakeLock.release();
-			throw e;
-		}
-	}
-
-	@Override
-	public void executeWakefully(Runnable r, String tag) {
-		AndroidWakeLock wakeLock = createWakeLock(tag);
-		wakeLock.acquire();
-		try {
-			new Thread(() -> {
-				try {
-					r.run();
-				} finally {
-					wakeLock.release();
-				}
-			}).start();
-		} catch (Exception e) {
-			wakeLock.release();
-			throw e;
-		}
-	}
-
-	private String getWakeLockTag(Context ctx) {
-		PackageManager pm = ctx.getPackageManager();
-		for (PackageInfo info : pm.getInstalledPackages(0)) {
-			String name = info.packageName.toLowerCase();
-			if (name.startsWith("com.huawei.powergenie")) {
-				return "LocationManagerService";
-			} else if (name.startsWith("com.evenwell.powermonitor")) {
-				return "AudioIn";
-			}
-		}
-		return ctx.getPackageName();
-	}
-}

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidWakefulIoExecutorModule.java

@@ -1,23 +0,0 @@
-package org.briarproject.bramble.system;
-
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
-import org.briarproject.bramble.api.system.AndroidWakeLockManager;
-import org.briarproject.bramble.api.system.WakefulIoExecutor;
-
-import java.util.concurrent.Executor;
-
-import dagger.Module;
-import dagger.Provides;
-
-@Module
-public
-class AndroidWakefulIoExecutorModule {
-
-	@Provides
-	@WakefulIoExecutor
-	Executor provideWakefulIoExecutor(@IoExecutor Executor ioExecutor,
-			AndroidWakeLockManager wakeLockManager) {
-		return r -> wakeLockManager.executeWakefully(r, ioExecutor,
-				"WakefulIoExecutor");
-	}
-}

bramble-android/src/main/java/org/briarproject/bramble/system/RenewableWakeLock.java

@@ -1,130 +0,0 @@
-package org.briarproject.bramble.system;
-
-import android.os.PowerManager;
-import android.os.PowerManager.WakeLock;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.util.concurrent.Future;
-import java.util.concurrent.ScheduledExecutorService;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-import javax.annotation.concurrent.GuardedBy;
-import javax.annotation.concurrent.ThreadSafe;
-
-import static java.util.concurrent.TimeUnit.MILLISECONDS;
-import static java.util.logging.Level.FINE;
-import static java.util.logging.Level.INFO;
-import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
-
-@ThreadSafe
-@NotNullByDefault
-class RenewableWakeLock implements SharedWakeLock {
-
-	private static final Logger LOG =
-			getLogger(RenewableWakeLock.class.getName());
-
-	private final PowerManager powerManager;
-	private final ScheduledExecutorService scheduledExecutorService;
-	private final int levelAndFlags;
-	private final String tag;
-	private final long durationMs, safetyMarginMs;
-
-	private final Object lock = new Object();
-	@GuardedBy("lock")
-	@Nullable
-	private WakeLock wakeLock;
-	@GuardedBy("lock")
-	@Nullable
-	private Future<?> future;
-	@GuardedBy("lock")
-	private int refCount = 0;
-	@GuardedBy("lock")
-	private long acquired = 0;
-
-	RenewableWakeLock(PowerManager powerManager,
-			ScheduledExecutorService scheduledExecutorService,
-			int levelAndFlags,
-			String tag,
-			long durationMs,
-			long safetyMarginMs) {
-		this.powerManager = powerManager;
-		this.scheduledExecutorService = scheduledExecutorService;
-		this.levelAndFlags = levelAndFlags;
-		this.tag = tag;
-		this.durationMs = durationMs;
-		this.safetyMarginMs = safetyMarginMs;
-	}
-
-	@Override
-	public void acquire() {
-		synchronized (lock) {
-			refCount++;
-			if (refCount == 1) {
-				if (LOG.isLoggable(INFO)) {
-					LOG.info("Acquiring wake lock " + tag);
-				}
-				wakeLock = powerManager.newWakeLock(levelAndFlags, tag);
-				// We do our own reference counting so we can replace the lock
-				// TODO: Check whether using a ref-counted wake lock affects
-				//  power management apps
-				wakeLock.setReferenceCounted(false);
-				wakeLock.acquire(durationMs + safetyMarginMs);
-				future = scheduledExecutorService.schedule(this::renew,
-						durationMs, MILLISECONDS);
-				acquired = android.os.SystemClock.elapsedRealtime();
-			} else if (LOG.isLoggable(FINE)) {
-				LOG.fine("Wake lock " + tag + " has " + refCount + " holders");
-			}
-		}
-	}
-
-	private void renew() {
-		if (LOG.isLoggable(INFO)) LOG.info("Renewing wake lock " + tag);
-		synchronized (lock) {
-			if (wakeLock == null) {
-				LOG.info("Already released");
-				return;
-			}
-			if (LOG.isLoggable(FINE)) {
-				LOG.fine("Wake lock " + tag + " has " + refCount + " holders");
-			}
-			long now = android.os.SystemClock.elapsedRealtime();
-			long expiry = acquired + durationMs + safetyMarginMs;
-			if (now > expiry && LOG.isLoggable(WARNING)) {
-				LOG.warning("Wake lock expired " + (now - expiry) + " ms ago");
-			}
-			WakeLock oldWakeLock = wakeLock;
-			wakeLock = powerManager.newWakeLock(levelAndFlags, tag);
-			wakeLock.setReferenceCounted(false);
-			wakeLock.acquire(durationMs + safetyMarginMs);
-			oldWakeLock.release();
-			future = scheduledExecutorService.schedule(this::renew, durationMs,
-					MILLISECONDS);
-			acquired = now;
-		}
-	}
-
-	@Override
-	public void release() {
-		synchronized (lock) {
-			refCount--;
-			if (refCount == 0) {
-				if (LOG.isLoggable(INFO)) {
-					LOG.info("Releasing wake lock " + tag);
-				}
-				requireNonNull(future).cancel(false);
-				future = null;
-				requireNonNull(wakeLock).release();
-				wakeLock = null;
-				acquired = 0;
-			} else if (LOG.isLoggable(FINE)) {
-				LOG.fine("Wake lock " + tag + " has " + refCount + " holders");
-			}
-		}
-	}
-}
-

bramble-android/src/main/java/org/briarproject/bramble/system/SharedWakeLock.java

@@ -1,22 +0,0 @@
-package org.briarproject.bramble.system;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.system.AndroidWakeLock;
-
-@NotNullByDefault
-interface SharedWakeLock {
-
-	/**
-	 * Acquires the wake lock. This increments the wake lock's reference count,
-	 * so unlike {@link AndroidWakeLock#acquire()} every call to this method
-	 * must be followed by a balancing call to {@link #release()}.
-	 */
-	void acquire();
-
-	/**
-	 * Releases the wake lock. This decrements the wake lock's reference count,
-	 * so unlike {@link AndroidWakeLock#release()} every call to this method
-	 * must follow a balancing call to {@link #acquire()}.
-	 */
-	void release();
-}

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

@@ -3,6 +3,8 @@ package org.briarproject.bramble.util;
 import android.annotation.SuppressLint;
 import android.bluetooth.BluetoothAdapter;
 import android.content.Context;
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager;
 import android.os.Build;
 import android.provider.Settings;
 
@@ -117,4 +119,17 @@ public class AndroidUtils {
 		if (SDK_INT < 24) return new String[] {"image/jpeg", "image/png"};
 		else return new String[] {"image/jpeg", "image/png", "image/gif"};
 	}
+
+	public static String getWakeLockTag(Context ctx) {
+		PackageManager pm = ctx.getPackageManager();
+		for (PackageInfo info : pm.getInstalledPackages(0)) {
+			String name = info.packageName.toLowerCase();
+			if (name.startsWith("com.huawei.powergenie")) {
+				return "LocationManagerService";
+			} else if (name.startsWith("com.evenwell.powermonitor")) {
+				return "AudioIn";
+			}
+		}
+		return ctx.getPackageName();
+	}
 }

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

@@ -0,0 +1,100 @@
+package org.briarproject.bramble.util;
+
+import android.os.PowerManager;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
+
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.logging.Level.INFO;
+
+@ThreadSafe
+@NotNullByDefault
+public class RenewableWakeLock {
+
+	private static final Logger LOG =
+			Logger.getLogger(RenewableWakeLock.class.getName());
+
+	/**
+	 * Automatically release the lock this many milliseconds after it's due
+	 * to have been replaced and released.
+	 */
+	private static final int SAFETY_MARGIN_MS = 10_000;
+
+	private final PowerManager powerManager;
+	private final ScheduledExecutorService scheduler;
+	private final int levelAndFlags;
+	private final String tag;
+	private final long durationMs;
+	private final Runnable renewTask;
+
+	private final Object lock = new Object();
+	@Nullable
+	private PowerManager.WakeLock wakeLock; // Locking: lock
+	@Nullable
+	private ScheduledFuture future; // Locking: lock
+
+	public RenewableWakeLock(PowerManager powerManager,
+			ScheduledExecutorService scheduler, int levelAndFlags, String tag,
+			long duration, TimeUnit timeUnit) {
+		this.powerManager = powerManager;
+		this.scheduler = scheduler;
+		this.levelAndFlags = levelAndFlags;
+		this.tag = tag;
+		durationMs = MILLISECONDS.convert(duration, timeUnit);
+		renewTask = this::renew;
+	}
+
+	public void acquire() {
+		if (LOG.isLoggable(INFO)) LOG.info("Acquiring wake lock " + tag);
+		synchronized (lock) {
+			if (wakeLock != null) {
+				LOG.info("Already acquired");
+				return;
+			}
+			wakeLock = powerManager.newWakeLock(levelAndFlags, tag);
+			wakeLock.setReferenceCounted(false);
+			wakeLock.acquire(durationMs + SAFETY_MARGIN_MS);
+			future = scheduler.schedule(renewTask, durationMs, MILLISECONDS);
+		}
+	}
+
+	private void renew() {
+		if (LOG.isLoggable(INFO)) LOG.info("Renewing wake lock " + tag);
+		synchronized (lock) {
+			if (wakeLock == null) {
+				LOG.info("Already released");
+				return;
+			}
+			PowerManager.WakeLock oldWakeLock = wakeLock;
+			wakeLock = powerManager.newWakeLock(levelAndFlags, tag);
+			wakeLock.setReferenceCounted(false);
+			wakeLock.acquire(durationMs + SAFETY_MARGIN_MS);
+			oldWakeLock.release();
+			future = scheduler.schedule(renewTask, durationMs, MILLISECONDS);
+		}
+	}
+
+	public void release() {
+		if (LOG.isLoggable(INFO)) LOG.info("Releasing wake lock " + tag);
+		synchronized (lock) {
+			if (wakeLock == null) {
+				LOG.info("Already released");
+				return;
+			}
+			if (future == null) throw new AssertionError();
+			future.cancel(false);
+			future = null;
+			wakeLock.release();
+			wakeLock = null;
+		}
+	}
+}
+

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

@@ -1,25 +0,0 @@
-package org.briarproject.bramble.api;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.util.concurrent.atomic.AtomicReference;
-
-import javax.annotation.Nullable;
-
-/**
- * An item that can be consumed once.
- */
-@NotNullByDefault
-public class Consumable<T> {
-
-	private final AtomicReference<T> reference;
-
-	public Consumable(T item) {
-		reference = new AtomicReference<>(item);
-	}
-
-	@Nullable
-	public T consume() {
-		return reference.getAndSet(null);
-	}
-}

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

@@ -35,24 +35,24 @@ public interface ClientHelper {
 
 	Message createMessageForStoringMetadata(GroupId g);
 
-	Message getSmallMessage(MessageId m) throws DbException;
+	Message getMessage(MessageId m) throws DbException;
 
-	Message getSmallMessage(Transaction txn, MessageId m) throws DbException;
+	Message getMessage(Transaction txn, MessageId m) throws DbException;
 
-	BdfList getSmallMessageAsList(MessageId m)
+	BdfList getMessageAsList(MessageId m) throws DbException, FormatException;
-			throws DbException, FormatException;
 
-	BdfList getSmallMessageAsList(Transaction txn, MessageId m)
+	BdfList getMessageAsList(Transaction txn, MessageId m) throws DbException,
-			throws DbException, FormatException;
+			FormatException;
 
-	BdfDictionary getGroupMetadataAsDictionary(GroupId g)
+	BdfDictionary getGroupMetadataAsDictionary(GroupId g) throws DbException,
-			throws DbException, FormatException;
+			FormatException;
 
 	BdfDictionary getGroupMetadataAsDictionary(Transaction txn, GroupId g)
 			throws DbException, FormatException;
 
 	BdfDictionary getMessageMetadataAsDictionary(MessageId m)
-			throws DbException, FormatException;
+			throws DbException,
+			FormatException;
 
 	BdfDictionary getMessageMetadataAsDictionary(Transaction txn, MessageId m)
 			throws DbException, FormatException;
@@ -67,8 +67,8 @@ public interface ClientHelper {
 			BdfDictionary query) throws DbException, FormatException;
 
 	Map<MessageId, BdfDictionary> getMessageMetadataAsDictionary(
-			Transaction txn, GroupId g, BdfDictionary query)
+			Transaction txn, GroupId g, BdfDictionary query) throws DbException,
-			throws DbException, FormatException;
+			FormatException;
 
 	void mergeGroupMetadata(GroupId g, BdfDictionary metadata)
 			throws DbException, FormatException;

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

@@ -163,23 +163,27 @@ public interface DatabaseComponent extends TransactionManager {
 	 * less than or equal to the given length, for transmission over a
 	 * transport with the given maximum latency. Returns null if there are no
 	 * sendable messages that fit in the given length.
-	 *
-	 * @param small True if only single-block messages should be sent
 	 */
 	@Nullable
 	Collection<Message> generateBatch(Transaction txn, ContactId c,
-			int maxLength, int maxLatency, boolean small) throws DbException;
+			int maxLength, int maxLatency) throws DbException;
 
 	/**
 	 * Returns an offer for the given contact for transmission over a
 	 * transport with the given maximum latency, or null if there are no
 	 * messages to offer.
-	 *
-	 * @param small True if only single-block messages should be offered
 	 */
 	@Nullable
 	Offer generateOffer(Transaction txn, ContactId c, int maxMessages,
-			int maxLatency, boolean small) throws DbException;
+			int maxLatency) throws DbException;
+
+	/**
+	 * Returns a request for the given contact, or null if there are no
+	 * messages to request.
+	 */
+	@Nullable
+	Request generateRequest(Transaction txn, ContactId c, int maxMessages)
+			throws DbException;
 
 	/**
 	 * Returns a batch of messages for the given contact, with a total length
@@ -268,14 +272,13 @@ public interface DatabaseComponent extends TransactionManager {
 	Collection<Identity> getIdentities(Transaction txn) throws DbException;
 
 	/**
-	 * Returns the single-block message with the given ID.
+	 * Returns the message with the given ID.
 	 * <p/>
 	 * Read-only.
 	 *
 	 * @throws MessageDeletedException if the message has been deleted
-	 * @throws MessageTooLargeException if the message has more than one block
 	 */
-	Message getSmallMessage(Transaction txn, MessageId m) throws DbException;
+	Message getMessage(Transaction txn, MessageId m) throws DbException;
 
 	/**
 	 * Returns the IDs of all delivered messages in the given group.

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

@@ -1,8 +0,0 @@
-package org.briarproject.bramble.api.db;
-
-/**
- * Thrown when a multi-block message is requested from the database via a
- * method that is only suitable for requesting single-block messages.
- */
-public class MessageTooLargeException extends DbException {
-}

bramble-api/src/main/java/org/briarproject/bramble/api/io/TimeoutMonitor.java

@@ -7,10 +7,6 @@ public interface TimeoutMonitor {
 	/**
 	 * Returns an {@link InputStream} that wraps the given stream and allows
 	 * read timeouts to be detected.
-	 * <p>
-	 * The returned stream must be {@link InputStream#close() closed} when it's
-	 * no longer needed to ensure that resources held by the timeout monitor
-	 * are released.
 	 *
 	 * @param timeoutMs The read timeout in milliseconds. Timeouts will be
 	 * detected eventually but are not guaranteed to be detected immediately.

bramble-api/src/main/java/org/briarproject/bramble/api/lifecycle/LifecycleManager.java

@@ -5,7 +5,6 @@ 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.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.system.Wakeful;
 
 import java.util.concurrent.ExecutorService;
 
@@ -66,7 +65,6 @@ public interface LifecycleManager {
 	 * Opens the {@link DatabaseComponent} using the given key and starts any
 	 * registered {@link Service Services}.
 	 */
-	@Wakeful
 	StartResult startServices(SecretKey dbKey);
 
 	/**
@@ -74,7 +72,6 @@ public interface LifecycleManager {
 	 * registered {@link ExecutorService ExecutorServices}, and closes the
 	 * {@link DatabaseComponent}.
 	 */
-	@Wakeful
 	void stopServices();
 
 	/**
@@ -107,7 +104,6 @@ public interface LifecycleManager {
 		 *
 		 * @param txn A read-write transaction
 		 */
-		@Wakeful
 		void onDatabaseOpened(Transaction txn) throws DbException;
 	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/lifecycle/Service.java

@@ -1,20 +1,16 @@
 package org.briarproject.bramble.api.lifecycle;
 
-import org.briarproject.bramble.api.system.Wakeful;
-
 public interface Service {
 
 	/**
-	 * Starts the service. This method must not be called concurrently with
+	 * Starts the service.This method must not be called concurrently with
 	 * {@link #stopService()}.
 	 */
-	@Wakeful
 	void startService() throws ServiceException;
 
 	/**
 	 * Stops the service. This method must not be called concurrently with
 	 * {@link #startService()}.
 	 */
-	@Wakeful
 	void stopService() throws ServiceException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/Backoff.java

@@ -1,22 +0,0 @@
-package org.briarproject.bramble.api.plugin;
-
-/**
- * Calculates polling intervals for transport plugins that use backoff.
- */
-public interface Backoff {
-
-	/**
-	 * Returns the current polling interval.
-	 */
-	int getPollingInterval();
-
-	/**
-	 * Increments the backoff counter.
-	 */
-	void increment();
-
-	/**
-	 * Resets the backoff counter.
-	 */
-	void reset();
-}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/BackoffFactory.java

@@ -1,7 +0,0 @@
-package org.briarproject.bramble.api.plugin;
-
-public interface BackoffFactory {
-
-	Backoff createBackoff(int minInterval, int maxInterval,
-			double base);
-}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/BluetoothConstants.java

@@ -10,12 +10,6 @@ public interface BluetoothConstants {
 	String PROP_ADDRESS = "address";
 	String PROP_UUID = "uuid";
 
-	// Local settings (not shared with contacts)
+	// Default value for PREF_PLUGIN_ENABLE
-	String PREF_ADDRESS_IS_REFLECTED = "addressIsReflected";
-	String PREF_EVER_CONNECTED = "everConnected";
-
-	// Default values for local settings
 	boolean DEFAULT_PREF_PLUGIN_ENABLE = false;
-	boolean DEFAULT_PREF_ADDRESS_IS_REFLECTED = false;
-	boolean DEFAULT_PREF_EVER_CONNECTED = false;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/Plugin.java

@@ -4,7 +4,6 @@ import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.settings.SettingsManager;
-import org.briarproject.bramble.api.system.Wakeful;
 
 import java.util.Collection;
 
@@ -71,13 +70,11 @@ public interface Plugin {
 	/**
 	 * Starts the plugin.
 	 */
-	@Wakeful
 	void start() throws PluginException;
 
 	/**
 	 * Stops the plugin.
 	 */
-	@Wakeful
 	void stop() throws PluginException;
 
 	/**
@@ -109,7 +106,6 @@ public interface Plugin {
 	 * Attempts to create connections using the given transport properties,
 	 * passing any created connections to the corresponding handlers.
 	 */
-	@Wakeful
 	void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
 			properties);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/PluginCallback.java

@@ -8,8 +8,6 @@ import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.settings.Settings;
 
-import java.util.Collection;
-
 /**
  * An interface through which a transport plugin interacts with the rest of
  * the application.
@@ -27,11 +25,6 @@ public interface PluginCallback extends ConnectionHandler {
 	 */
 	TransportProperties getLocalProperties();
 
-	/**
-	 * Returns the plugin's remote transport properties.
-	 */
-	Collection<TransportProperties> getRemoteProperties();
-
 	/**
 	 * Merges the given settings with the plugin's settings
 	 */

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/duplex/DuplexPlugin.java

@@ -8,7 +8,6 @@ import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
 import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
-import org.briarproject.bramble.api.system.Wakeful;
 
 import javax.annotation.Nullable;
 
@@ -22,7 +21,6 @@ public interface DuplexPlugin extends Plugin {
 	 * Attempts to create and return a connection using the given transport
 	 * properties. Returns null if a connection cannot be created.
 	 */
-	@Wakeful
 	@Nullable
 	DuplexTransportConnection createConnection(TransportProperties p);
 

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/event/BluetoothEnabledEvent.java

@@ -0,0 +1,15 @@
+package org.briarproject.bramble.api.plugin.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that informs the Bluetooth plugin that we have enabled the
+ * Bluetooth adapter.
+ */
+@Immutable
+@NotNullByDefault
+public class BluetoothEnabledEvent extends Event {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/event/DisableBluetoothEvent.java

@@ -0,0 +1,15 @@
+package org.briarproject.bramble.api.plugin.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that asks the Bluetooth plugin to disable the Bluetooth adapter if
+ * we previously enabled it.
+ */
+@Immutable
+@NotNullByDefault
+public class DisableBluetoothEvent extends Event {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/event/EnableBluetoothEvent.java

@@ -0,0 +1,14 @@
+package org.briarproject.bramble.api.plugin.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that asks the Bluetooth plugin to enable the Bluetooth adapter.
+ */
+@Immutable
+@NotNullByDefault
+public class EnableBluetoothEvent extends Event {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/simplex/SimplexPlugin.java

@@ -5,7 +5,6 @@ import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
 import org.briarproject.bramble.api.properties.TransportProperties;
-import org.briarproject.bramble.api.system.Wakeful;
 
 import javax.annotation.Nullable;
 
@@ -19,7 +18,6 @@ public interface SimplexPlugin extends Plugin {
 	 * Attempts to create and return a reader for the given transport
 	 * properties. Returns null if a reader cannot be created.
 	 */
-	@Wakeful
 	@Nullable
 	TransportConnectionReader createReader(TransportProperties p);
 
@@ -27,7 +25,6 @@ public interface SimplexPlugin extends Plugin {
 	 * Attempts to create and return a writer for the given transport
 	 * properties. Returns null if a writer cannot be created.
 	 */
-	@Wakeful
 	@Nullable
 	TransportConnectionWriter createWriter(TransportProperties p);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/properties/TransportPropertyConstants.java

@@ -12,11 +12,6 @@ public interface TransportPropertyConstants {
 	 */
 	int MAX_PROPERTY_LENGTH = 100;
 
-	/**
-	 * Prefix for keys that represent reflected properties.
-	 */
-	String REFLECTED_PROPERTY_PREFIX = "u:";
-
 	/**
 	 * Message metadata key for the transport ID of a local or remote update,
 	 * as a BDF string.

bramble-api/src/main/java/org/briarproject/bramble/api/properties/event/RemoteTransportPropertiesUpdatedEvent.java

@@ -1,27 +0,0 @@
-package org.briarproject.bramble.api.properties.event;
-
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.TransportId;
-import org.briarproject.bramble.api.properties.TransportProperties;
-
-import javax.annotation.concurrent.Immutable;
-
-/**
- * An event that is broadcast when {@link TransportProperties} are received
- * from a contact.
- */
-@Immutable
-@NotNullByDefault
-public class RemoteTransportPropertiesUpdatedEvent extends Event {
-
-	private final TransportId transportId;
-
-	public RemoteTransportPropertiesUpdatedEvent(TransportId transportId) {
-		this.transportId = transportId;
-	}
-
-	public TransportId getTransportId() {
-		return transportId;
-	}
-}

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

@@ -29,15 +29,10 @@ public interface SyncConstants {
 	 */
 	int MESSAGE_HEADER_LENGTH = UniqueId.LENGTH + 8;
 
-	/**
-	 * The maximum length of a block in bytes.
-	 */
-	int MAX_BLOCK_LENGTH = 32 * 1024; // 32 KiB
-
 	/**
 	 * The maximum length of a message body in bytes.
 	 */
-	int MAX_MESSAGE_BODY_LENGTH = MAX_BLOCK_LENGTH;
+	int MAX_MESSAGE_BODY_LENGTH = 32 * 1024; // 32 KiB
 
 	/**
 	 * The maximum length of a message in bytes.

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

@@ -7,16 +7,16 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import javax.annotation.concurrent.Immutable;
 
 /**
- * An event that is broadcast when one or more messages are received from, or
+ * An event that is broadcast when a message is received from, or offered by, a
- * offered by, a contact and need to be acknowledged.
+ * contact and needs to be acknowledged.
  */
 @Immutable
 @NotNullByDefault
-public class MessagesToAckEvent extends Event {
+public class MessageToAckEvent extends Event {
 
 	private final ContactId contactId;
 
-	public MessagesToAckEvent(ContactId contactId) {
+	public MessageToAckEvent(ContactId contactId) {
 		this.contactId = contactId;
 	}
 

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

@@ -0,0 +1,26 @@
+package org.briarproject.bramble.api.sync.event;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a message is offered by a contact and needs
+ * to be requested.
+ */
+@Immutable
+@NotNullByDefault
+public class MessageToRequestEvent extends Event {
+
+	private final ContactId contactId;
+
+	public MessageToRequestEvent(ContactId contactId) {
+		this.contactId = contactId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

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

@@ -1,39 +0,0 @@
-package org.briarproject.bramble.api.sync.event;
-
-import org.briarproject.bramble.api.Consumable;
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageId;
-
-import java.util.Collection;
-
-import javax.annotation.Nullable;
-import javax.annotation.concurrent.Immutable;
-
-/**
- * An event that is broadcast when one or more messages are offered by a
- * contact and need to be requested.
- */
-@Immutable
-@NotNullByDefault
-public class MessagesToRequestEvent extends Event {
-
-	private final ContactId contactId;
-	private final Consumable<Collection<MessageId>> ids;
-
-	public MessagesToRequestEvent(ContactId contactId,
-			Collection<MessageId> ids) {
-		this.contactId = contactId;
-		this.ids = new Consumable<>(ids);
-	}
-
-	public ContactId getContactId() {
-		return contactId;
-	}
-
-	@Nullable
-	public Collection<MessageId> consumeIds() {
-		return ids.consume();
-	}
-}

bramble-api/src/main/java/org/briarproject/bramble/api/system/Scheduler.java

@@ -1,6 +1,5 @@
-package org.briarproject.bramble.api.plugin;
+package org.briarproject.bramble.api.system;
 
-import java.io.File;
 import java.lang.annotation.Retention;
 import java.lang.annotation.Target;
 
@@ -12,11 +11,15 @@ import static java.lang.annotation.ElementType.PARAMETER;
 import static java.lang.annotation.RetentionPolicy.RUNTIME;
 
 /**
- * Annotation for injecting the {@link File directory} where the Tor plugin
+ * Annotation for injecting a scheduled executor service
- * should store its state.
+ * that can be used to schedule the execution of tasks.
+ * <p>
+ * The service should <b>only</b> be used for running tasks on other executors
+ * at scheduled times.
+ * No significant work should be run by the service itself!
  */
 @Qualifier
 @Target({FIELD, METHOD, PARAMETER})
 @Retention(RUNTIME)
-public @interface TorDirectory {
+public @interface Scheduler {
-}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/system/TaskScheduler.java

@@ -1,43 +0,0 @@
-package org.briarproject.bramble.api.system;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-import java.util.concurrent.Executor;
-import java.util.concurrent.TimeUnit;
-
-/**
- * A service that can be used to schedule the execution of tasks.
- */
-@NotNullByDefault
-public interface TaskScheduler {
-
-	/**
-	 * Submits the given task to the given executor after the given delay.
-	 * <p>
-	 * If the platform supports wake locks, a wake lock will be held while
-	 * submitting and running the task.
-	 */
-	Cancellable schedule(Runnable task, Executor executor, long delay,
-			TimeUnit unit);
-
-	/**
-	 * Submits the given task to the given executor after the given delay,
-	 * and then repeatedly with the given interval between executions
-	 * (measured from the end of one execution to the beginning of the next).
-	 * <p>
-	 * If the platform supports wake locks, a wake lock will be held while
-	 * submitting and running the task.
-	 */
-	Cancellable scheduleWithFixedDelay(Runnable task, Executor executor,
-			long delay, long interval, TimeUnit unit);
-
-	interface Cancellable {
-
-		/**
-		 * Cancels the task if it has not already started running. If the task
-		 * is {@link #scheduleWithFixedDelay(Runnable, Executor, long, long, TimeUnit) periodic},
-		 * all future executions of the task are cancelled.
-		 */
-		void cancel();
-	}
-}

bramble-api/src/main/java/org/briarproject/bramble/api/system/Wakeful.java

@@ -1,19 +0,0 @@
-package org.briarproject.bramble.api.system;
-
-import java.lang.annotation.Retention;
-import java.lang.annotation.Target;
-
-import javax.inject.Qualifier;
-
-import static java.lang.annotation.ElementType.METHOD;
-import static java.lang.annotation.RetentionPolicy.RUNTIME;
-
-/**
- * Annotation for methods that must be called while holding a wake lock, if
- * the platform supports wake locks.
- */
-@Qualifier
-@Target(METHOD)
-@Retention(RUNTIME)
-public @interface Wakeful {
-}

bramble-api/src/main/java/org/briarproject/bramble/api/system/WakefulIoExecutor.java

@@ -1,26 +0,0 @@
-package org.briarproject.bramble.api.system;
-
-import java.lang.annotation.Retention;
-import java.lang.annotation.Target;
-
-import javax.inject.Qualifier;
-
-import static java.lang.annotation.ElementType.FIELD;
-import static java.lang.annotation.ElementType.METHOD;
-import static java.lang.annotation.ElementType.PARAMETER;
-import static java.lang.annotation.RetentionPolicy.RUNTIME;
-
-/**
- * Annotation for injecting the executor for long-running IO tasks that should
- * run without sleeping. Also used for annotating methods that should run on
- * this executor.
- * <p>
- * The contract of this executor is that tasks may be run concurrently, and
- * submitting a task will never block. Tasks must not run indefinitely. Tasks
- * submitted during shutdown are discarded.
- */
-@Qualifier
-@Target({FIELD, METHOD, PARAMETER})
-@Retention(RUNTIME)
-public @interface WakefulIoExecutor {
-}

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

@@ -9,6 +9,7 @@ import org.briarproject.bramble.plugin.PluginModule;
 import org.briarproject.bramble.properties.PropertiesModule;
 import org.briarproject.bramble.rendezvous.RendezvousModule;
 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;
 
@@ -30,6 +31,8 @@ public interface BrambleCoreEagerSingletons {
 
 	void inject(RendezvousModule.EagerSingletons init);
 
+	void inject(SystemModule.EagerSingletons init);
+
 	void inject(TransportModule.EagerSingletons init);
 
 	void inject(ValidationModule.EagerSingletons init);
@@ -47,6 +50,7 @@ public interface BrambleCoreEagerSingletons {
 			c.inject(new RendezvousModule.EagerSingletons());
 			c.inject(new PluginModule.EagerSingletons());
 			c.inject(new PropertiesModule.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/BrambleCoreModule.java

@@ -21,7 +21,7 @@ import org.briarproject.bramble.rendezvous.RendezvousModule;
 import org.briarproject.bramble.settings.SettingsModule;
 import org.briarproject.bramble.sync.SyncModule;
 import org.briarproject.bramble.sync.validation.ValidationModule;
-import org.briarproject.bramble.system.ClockModule;
+import org.briarproject.bramble.system.SystemModule;
 import org.briarproject.bramble.transport.TransportModule;
 import org.briarproject.bramble.versioning.VersioningModule;
 
@@ -29,7 +29,6 @@ import dagger.Module;
 
 @Module(includes = {
 		ClientModule.class,
-		ClockModule.class,
 		ConnectionModule.class,
 		ContactModule.class,
 		CryptoModule.class,
@@ -49,6 +48,7 @@ import dagger.Module;
 		RendezvousModule.class,
 		SettingsModule.class,
 		SyncModule.class,
+		SystemModule.class,
 		TransportModule.class,
 		ValidationModule.class,
 		VersioningModule.class

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

@@ -116,27 +116,25 @@ class ClientHelperImpl implements ClientHelper {
 	}
 
 	@Override
-	public Message getSmallMessage(MessageId m) throws DbException {
+	public Message getMessage(MessageId m) throws DbException {
-		return db.transactionWithResult(true, txn -> getSmallMessage(txn, m));
+		return db.transactionWithResult(true, txn -> getMessage(txn, m));
 	}
 
 	@Override
-	public Message getSmallMessage(Transaction txn, MessageId m)
+	public Message getMessage(Transaction txn, MessageId m) throws DbException {
-			throws DbException {
+		return db.getMessage(txn, m);
-		return db.getSmallMessage(txn, m);
 	}
 
 	@Override
-	public BdfList getSmallMessageAsList(MessageId m)
+	public BdfList getMessageAsList(MessageId m) throws DbException,
+			FormatException {
+		return db.transactionWithResult(true, txn -> getMessageAsList(txn, m));
+	}
+
+	@Override
+	public BdfList getMessageAsList(Transaction txn, MessageId m)
 			throws DbException, FormatException {
-		return db.transactionWithResult(true, txn ->
+		return toList(db.getMessage(txn, m).getBody());
-				getSmallMessageAsList(txn, m));
-	}
-
-	@Override
-	public BdfList getSmallMessageAsList(Transaction txn, MessageId m)
-			throws DbException, FormatException {
-		return toList(db.getSmallMessage(txn, m).getBody());
 	}
 
 	@Override

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

@@ -12,7 +12,6 @@ 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.MessageDeletedException;
-import org.briarproject.bramble.api.db.MessageTooLargeException;
 import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.identity.Author;
@@ -126,6 +125,11 @@ interface Database<T> {
 	void addMessageDependency(T txn, Message dependent, MessageId dependency,
 			MessageState dependentState) throws DbException;
 
+	/**
+	 * Records that a message has been offered by the given contact.
+	 */
+	void addOfferedMessage(T txn, ContactId c, MessageId m) throws DbException;
+
 	/**
 	 * Stores a pending contact.
 	 */
@@ -214,6 +218,13 @@ interface Database<T> {
 	boolean containsVisibleMessage(T txn, ContactId c, MessageId m)
 			throws DbException;
 
+	/**
+	 * Returns the number of messages offered by the given contact.
+	 * <p/>
+	 * Read-only.
+	 */
+	int countOfferedMessages(T txn, ContactId c) throws DbException;
+
 	/**
 	 * Deletes the message with the given ID. Unlike
 	 * {@link #removeMessage(Object, MessageId)}, the message ID and any other
@@ -321,14 +332,13 @@ interface Database<T> {
 	Collection<Identity> getIdentities(T txn) throws DbException;
 
 	/**
-	 * Returns the single-block message with the given ID.
+	 * Returns the message with the given ID.
 	 * <p/>
 	 * Read-only.
 	 *
 	 * @throws MessageDeletedException if the message has been deleted
-	 * @throws MessageTooLargeException if the message has more than one block
 	 */
-	Message getSmallMessage(T txn, MessageId m) throws DbException;
+	Message getMessage(T txn, MessageId m) throws DbException;
 
 	/**
 	 * Returns the IDs and states of all dependencies of the given message.
@@ -447,13 +457,13 @@ interface Database<T> {
 			int maxMessages, int maxLatency) throws DbException;
 
 	/**
-	 * Returns the IDs of some single-block messages that are eligible to be
+	 * Returns the IDs of some messages that are eligible to be requested from
-	 * offered to the given contact, up to the given number of messages.
+	 * the given contact, up to the given number of messages.
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<MessageId> getSmallMessagesToOffer(T txn, ContactId c,
+	Collection<MessageId> getMessagesToRequest(T txn, ContactId c,
-			int maxMessages, int maxLatency) throws DbException;
+			int maxMessages) throws DbException;
 
 	/**
 	 * Returns the IDs of some messages that are eligible to be sent to the
@@ -464,15 +474,6 @@ interface Database<T> {
 	Collection<MessageId> getMessagesToSend(T txn, ContactId c, int maxLength,
 			int maxLatency) throws DbException;
 
-	/**
-	 * Returns the IDs of some single-block messages that are eligible to be
-	 * sent to the given contact, up to the given total length.
-	 * <p/>
-	 * Read-only.
-	 */
-	Collection<MessageId> getSmallMessagesToSend(T txn, ContactId c,
-			int maxLength, int maxLatency) throws DbException;
-
 	/**
 	 * Returns the IDs of any messages that need to be validated.
 	 * <p/>
@@ -635,6 +636,13 @@ interface Database<T> {
 	 */
 	void removeMessage(T txn, MessageId m) throws DbException;
 
+	/**
+	 * Removes the given offered messages that were offered by the given
+	 * contact.
+	 */
+	void removeOfferedMessages(T txn, ContactId c,
+			Collection<MessageId> requested) throws DbException;
+
 	/**
 	 * Removes a pending contact (and all associated state) from the database.
 	 */

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

@@ -61,10 +61,10 @@ import org.briarproject.bramble.api.sync.event.MessageAddedEvent;
 import org.briarproject.bramble.api.sync.event.MessageRequestedEvent;
 import org.briarproject.bramble.api.sync.event.MessageSharedEvent;
 import org.briarproject.bramble.api.sync.event.MessageStateChangedEvent;
+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.event.MessagesToAckEvent;
-import org.briarproject.bramble.api.sync.event.MessagesToRequestEvent;
 import org.briarproject.bramble.api.sync.event.SyncVersionsUpdatedEvent;
 import org.briarproject.bramble.api.sync.validation.MessageState;
 import org.briarproject.bramble.api.transport.KeySetId;
@@ -91,6 +91,7 @@ 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.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;
 import static org.briarproject.bramble.util.LogUtils.now;
@@ -405,22 +406,19 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	@Nullable
 	@Override
 	public Collection<Message> generateBatch(Transaction transaction,
-			ContactId c, int maxLength, int maxLatency, boolean small)
+			ContactId c, int maxLength, int maxLatency) throws DbException {
-			throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
-		Collection<MessageId> ids;
+		Collection<MessageId> ids =
-		if (small)
+				db.getMessagesToSend(txn, c, maxLength, maxLatency);
-			ids = db.getSmallMessagesToSend(txn, c, maxLength, maxLatency);
-		else ids = db.getMessagesToSend(txn, c, maxLength, maxLatency);
-		if (ids.isEmpty()) return null;
 		List<Message> messages = new ArrayList<>(ids.size());
 		for (MessageId m : ids) {
-			messages.add(db.getSmallMessage(txn, m));
+			messages.add(db.getMessage(txn, m));
 			db.updateExpiryTimeAndEta(txn, c, m, maxLatency);
 		}
+		if (ids.isEmpty()) return null;
 		db.lowerRequestedFlag(txn, c, ids);
 		transaction.attach(new MessagesSentEvent(c, ids));
 		return messages;
@@ -429,21 +427,34 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	@Nullable
 	@Override
 	public Offer generateOffer(Transaction transaction, ContactId c,
-			int maxMessages, int maxLatency, boolean small) throws DbException {
+			int maxMessages, int maxLatency) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
-		Collection<MessageId> ids;
+		Collection<MessageId> ids =
-		if (small)
+				db.getMessagesToOffer(txn, c, maxMessages, maxLatency);
-			ids = db.getSmallMessagesToOffer(txn, c, maxMessages, maxLatency);
-		else ids = db.getMessagesToOffer(txn, c, maxMessages, maxLatency);
 		if (ids.isEmpty()) return null;
 		for (MessageId m : ids)
 			db.updateExpiryTimeAndEta(txn, c, m, maxLatency);
 		return new Offer(ids);
 	}
 
+	@Nullable
+	@Override
+	public Request generateRequest(Transaction transaction, ContactId c,
+			int maxMessages) throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		Collection<MessageId> ids = db.getMessagesToRequest(txn, c,
+				maxMessages);
+		if (ids.isEmpty()) return null;
+		db.removeOfferedMessages(txn, c, ids);
+		return new Request(ids);
+	}
+
 	@Nullable
 	@Override
 	public Collection<Message> generateRequestedBatch(Transaction transaction,
@@ -454,12 +465,12 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 			throw new NoSuchContactException();
 		Collection<MessageId> ids =
 				db.getRequestedMessagesToSend(txn, c, maxLength, maxLatency);
-		if (ids.isEmpty()) return null;
 		List<Message> messages = new ArrayList<>(ids.size());
 		for (MessageId m : ids) {
-			messages.add(db.getSmallMessage(txn, m));
+			messages.add(db.getMessage(txn, m));
 			db.updateExpiryTimeAndEta(txn, c, m, maxLatency);
 		}
+		if (ids.isEmpty()) return null;
 		db.lowerRequestedFlag(txn, c, ids);
 		transaction.attach(new MessagesSentEvent(c, ids));
 		return messages;
@@ -548,12 +559,12 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public Message getSmallMessage(Transaction transaction, MessageId m)
+	public Message getMessage(Transaction transaction, MessageId m)
 			throws DbException {
 		T txn = unbox(transaction);
 		if (!db.containsMessage(txn, m))
 			throw new NoSuchMessageException();
-		return db.getSmallMessage(txn, m);
+		return db.getMessage(txn, m);
 	}
 
 	@Override
@@ -808,7 +819,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 				db.addMessage(txn, m, UNKNOWN, false, false, c);
 				transaction.attach(new MessageAddedEvent(m, c));
 			}
-			transaction.attach(new MessagesToAckEvent(c));
+			transaction.attach(new MessageToAckEvent(c));
 		}
 	}
 
@@ -819,20 +830,21 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
-		boolean ack = false;
+		boolean ack = false, request = false;
-		List<MessageId> request = new ArrayList<>(o.getMessageIds().size());
+		int count = db.countOfferedMessages(txn, c);
 		for (MessageId m : o.getMessageIds()) {
 			if (db.containsVisibleMessage(txn, c, m)) {
 				db.raiseSeenFlag(txn, c, m);
 				db.raiseAckFlag(txn, c, m);
 				ack = true;
-			} else {
+			} else if (count < MAX_OFFERED_MESSAGES) {
-				request.add(m);
+				db.addOfferedMessage(txn, c, m);
+				request = true;
+				count++;
 			}
 		}
-		if (ack) transaction.attach(new MessagesToAckEvent(c));
+		if (ack) transaction.attach(new MessageToAckEvent(c));
-		if (!request.isEmpty())
+		if (request) transaction.attach(new MessageToRequestEvent(c));
-			transaction.attach(new MessagesToRequestEvent(c, request));
 	}
 
 	@Override

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

@@ -6,6 +6,13 @@ import static java.util.concurrent.TimeUnit.DAYS;
 
 interface DatabaseConstants {
 
+	/**
+	 * The maximum number of offered messages from each contact that will be
+	 * stored. If offers arrive more quickly than requests can be sent and this
+	 * limit is reached, additional offers will not be stored.
+	 */
+	int MAX_OFFERED_MESSAGES = 1000;
+
 	/**
 	 * The namespace of the {@link Settings} where the database schema version
 	 * is stored.

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

@@ -6,6 +6,7 @@ import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventExecutor;
 import org.briarproject.bramble.api.lifecycle.ShutdownManager;
+import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
 
 import java.sql.Connection;
@@ -21,8 +22,9 @@ public class DatabaseModule {
 
 	@Provides
 	@Singleton
-	Database<Connection> provideDatabase(DatabaseConfig config, Clock clock) {
+	Database<Connection> provideDatabase(DatabaseConfig config,
-		return new H2Database(config, clock);
+			MessageFactory messageFactory, Clock clock) {
+		return new H2Database(config, messageFactory, clock);
 	}
 
 	@Provides

bramble-core/src/main/java/org/briarproject/bramble/db/H2Database.java

@@ -6,6 +6,7 @@ import org.briarproject.bramble.api.db.DbClosedException;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.util.StringUtils;
 
@@ -50,8 +51,9 @@ class H2Database extends JdbcDatabase {
 	private volatile SecretKey key = null;
 
 	@Inject
-	H2Database(DatabaseConfig config, Clock clock) {
+	H2Database(DatabaseConfig config, MessageFactory messageFactory,
-		super(dbTypes, clock);
+			Clock clock) {
+		super(dbTypes, messageFactory, clock);
 		this.config = config;
 		File dir = config.getDatabaseDirectory();
 		String path = new File(dir, "db").getAbsolutePath();

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

@@ -6,6 +6,7 @@ import org.briarproject.bramble.api.db.DbClosedException;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.util.StringUtils;
 
@@ -50,8 +51,9 @@ class HyperSqlDatabase extends JdbcDatabase {
 	private volatile SecretKey key = null;
 
 	@Inject
-	HyperSqlDatabase(DatabaseConfig config, Clock clock) {
+	HyperSqlDatabase(DatabaseConfig config, MessageFactory messageFactory,
-		super(dbTypes, clock);
+			Clock clock) {
+		super(dbTypes, messageFactory, clock);
 		this.config = config;
 		File dir = config.getDatabaseDirectory();
 		String path = new File(dir, "db").getAbsolutePath();

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

@@ -16,7 +16,6 @@ import org.briarproject.bramble.api.db.DataTooOldException;
 import org.briarproject.bramble.api.db.DbClosedException;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.MessageDeletedException;
-import org.briarproject.bramble.api.db.MessageTooLargeException;
 import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.identity.Author;
@@ -31,6 +30,7 @@ import org.briarproject.bramble.api.sync.Group;
 import org.briarproject.bramble.api.sync.Group.Visibility;
 import org.briarproject.bramble.api.sync.GroupId;
 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.validation.MessageState;
@@ -76,7 +76,6 @@ import static org.briarproject.bramble.api.db.Metadata.REMOVE;
 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_BLOCK_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
 import static org.briarproject.bramble.api.sync.validation.MessageState.DELIVERED;
 import static org.briarproject.bramble.api.sync.validation.MessageState.PENDING;
@@ -99,7 +98,7 @@ import static org.briarproject.bramble.util.LogUtils.now;
 abstract class JdbcDatabase implements Database<Connection> {
 
 	// Package access for testing
-	static final int CODE_SCHEMA_VERSION = 49;
+	static final int CODE_SCHEMA_VERSION = 47;
 
 	// Time period offsets for incoming transport keys
 	private static final int OFFSET_PREV = -1;
@@ -181,9 +180,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " state INT NOT NULL,"
 					+ " shared BOOLEAN NOT NULL,"
 					+ " temporary BOOLEAN NOT NULL,"
-					+ " length INT NOT NULL," // Includes message header
+					+ " length INT NOT NULL,"
-					+ " deleted BOOLEAN NOT NULL,"
+					+ " raw BLOB," // Null if message has been deleted
-					+ " blockCount INT NOT NULL,"
 					+ " PRIMARY KEY (messageId),"
 					+ " FOREIGN KEY (groupId)"
 					+ " REFERENCES groups (groupId)"
@@ -220,15 +218,13 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " REFERENCES messages (messageId)"
 					+ " ON DELETE CASCADE)";
 
-	private static final String CREATE_BLOCKS =
+	private static final String CREATE_OFFERS =
-			"CREATE TABLE blocks"
+			"CREATE TABLE offers"
-					+ " (messageId _HASH NOT NULL,"
+					+ " (messageId _HASH NOT NULL," // Not a foreign key
-					+ " blockNumber INT NOT NULL,"
+					+ " contactId INT NOT NULL,"
-					+ " blockLength INT NOT NULL," // Excludes block header
+					+ " PRIMARY KEY (messageId, contactId),"
-					+ " data BLOB," // Null if message has been deleted
+					+ " FOREIGN KEY (contactId)"
-					+ " PRIMARY KEY (messageId, blockNumber),"
+					+ " REFERENCES contacts (contactId)"
-					+ " FOREIGN KEY (messageId)"
-					+ " REFERENCES messages (messageId)"
 					+ " ON DELETE CASCADE)";
 
 	private static final String CREATE_STATUSES =
@@ -343,6 +339,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	private static final Logger LOG =
 			getLogger(JdbcDatabase.class.getName());
 
+	private final MessageFactory messageFactory;
 	private final Clock clock;
 	private final DatabaseTypes dbTypes;
 
@@ -362,8 +359,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	protected abstract void compactAndClose() throws DbException;
 
-	JdbcDatabase(DatabaseTypes databaseTypes, Clock clock) {
+	JdbcDatabase(DatabaseTypes databaseTypes, MessageFactory messageFactory,
+			Clock clock) {
 		this.dbTypes = databaseTypes;
+		this.messageFactory = messageFactory;
 		this.clock = clock;
 	}
 
@@ -441,12 +440,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Migrating from schema " + start + " to " + end);
 				if (listener != null) listener.onDatabaseMigration();
-				long startTime = now();
 				// Apply the migration
 				m.migrate(txn);
 				// Store the new schema version
 				storeSchemaVersion(txn, end);
-				logDuration(LOG, "Migration", startTime);
 				dataSchemaVersion = end;
 			}
 		}
@@ -466,9 +463,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 				new Migration43_44(dbTypes),
 				new Migration44_45(),
 				new Migration45_46(),
-				new Migration46_47(dbTypes),
+				new Migration46_47(dbTypes)
-				new Migration47_48(dbTypes),
-				new Migration48_49()
 		);
 	}
 
@@ -513,7 +508,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_MESSAGES));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_MESSAGE_METADATA));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_MESSAGE_DEPENDENCIES));
-			s.executeUpdate(dbTypes.replaceTypes(CREATE_BLOCKS));
+			s.executeUpdate(dbTypes.replaceTypes(CREATE_OFFERS));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_STATUSES));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_TRANSPORTS));
 			s.executeUpdate(dbTypes.replaceTypes(CREATE_PENDING_CONTACTS));
@@ -731,7 +726,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		ResultSet rs = null;
 		try {
 			String sql = "SELECT messageId, timestamp, state, shared,"
-					+ " length, deleted"
+					+ " length, raw IS NULL"
 					+ " FROM messages"
 					+ " WHERE groupId = ?";
 			ps = txn.prepareStatement(sql);
@@ -744,8 +739,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 				boolean messageShared = rs.getBoolean(4);
 				int length = rs.getInt(5);
 				boolean deleted = rs.getBoolean(6);
+				boolean seen = removeOfferedMessage(txn, c, id);
 				addStatus(txn, id, c, g, timestamp, length, state, groupShared,
-						messageShared, deleted, false);
+						messageShared, deleted, seen);
 			}
 			rs.close();
 			ps.close();
@@ -792,8 +788,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		try {
 			String sql = "INSERT INTO messages (messageId, groupId, timestamp,"
-					+ " state, shared, temporary, length, deleted, blockCount)"
+					+ " state, shared, temporary, length, raw)"
-					+ " VALUES (?, ?, ?, ?, ?, ?, ?, FALSE, 1)";
+					+ " VALUES (?, ?, ?, ?, ?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getId().getBytes());
 			ps.setBytes(2, m.getGroupId().getBytes());
@@ -801,29 +797,21 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.setInt(4, state.getValue());
 			ps.setBoolean(5, shared);
 			ps.setBoolean(6, temporary);
-			ps.setInt(7, m.getRawLength());
+			byte[] raw = messageFactory.getRawMessage(m);
+			ps.setInt(7, raw.length);
+			ps.setBytes(8, raw);
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
-			sql = "INSERT INTO blocks (messageId, blockNumber, blockLength,"
-					+ " data)"
-					+ " VALUES (?, 0, ?, ?)";
-			ps = txn.prepareStatement(sql);
-			ps.setBytes(1, m.getId().getBytes());
-			ps.setInt(2, m.getBody().length);
-			ps.setBytes(3, m.getBody());
-			affected = ps.executeUpdate();
-			if (affected != 1) throw new DbStateException();
-			ps.close();
 			// Create a status row for each contact that can see the group
 			Map<ContactId, Boolean> visibility =
 					getGroupVisibility(txn, m.getGroupId());
 			for (Entry<ContactId, Boolean> e : visibility.entrySet()) {
 				ContactId c = e.getKey();
-				boolean seen = c.equals(sender);
+				boolean offered = removeOfferedMessage(txn, c, m.getId());
+				boolean seen = offered || c.equals(sender);
 				addStatus(txn, m.getId(), c, m.getGroupId(), m.getTimestamp(),
-						m.getRawLength(), state, e.getValue(), shared, false,
+						raw.length, state, e.getValue(), shared, false, seen);
-						seen);
 			}
 			// Update denormalised column in messageDependencies if dependency
 			// is in same group as dependent
@@ -842,6 +830,37 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public void addOfferedMessage(Connection txn, ContactId c, MessageId m)
+			throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT NULL FROM offers"
+					+ " WHERE messageId = ? AND contactId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			ps.setInt(2, c.getInt());
+			rs = ps.executeQuery();
+			boolean found = rs.next();
+			if (rs.next()) throw new DbStateException();
+			rs.close();
+			ps.close();
+			if (found) return;
+			sql = "INSERT INTO offers (messageId, contactId) VALUES (?, ?)";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			ps.setInt(2, c.getInt());
+			int affected = ps.executeUpdate();
+			if (affected != 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	private void addStatus(Connection txn, MessageId m, ContactId c, GroupId g,
 			long timestamp, int length, MessageState state, boolean groupShared,
 			boolean messageShared, boolean deleted, boolean seen)
@@ -1243,22 +1262,40 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public int countOfferedMessages(Connection txn, ContactId c)
+			throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT COUNT (messageId) FROM offers "
+					+ " WHERE contactId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			rs = ps.executeQuery();
+			if (!rs.next()) throw new DbException();
+			int count = rs.getInt(1);
+			if (rs.next()) throw new DbException();
+			rs.close();
+			ps.close();
+			return count;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void deleteMessage(Connection txn, MessageId m) throws DbException {
 		PreparedStatement ps = null;
 		try {
-			String sql = "UPDATE messages SET deleted = TRUE"
+			String sql = "UPDATE messages SET raw = NULL WHERE messageId = ?";
-					+ " WHERE messageId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			int affected = ps.executeUpdate();
-			if (affected < 0 || affected > 1) throw new DbStateException();
-			ps.close();
-			sql = "UPDATE blocks SET data = NULL WHERE messageId = ?";
-			ps = txn.prepareStatement(sql);
-			ps.setBytes(1, m.getBytes());
-			affected = ps.executeUpdate();
 			if (affected < 0) throw new DbStateException();
+			if (affected > 1) throw new DbStateException();
 			ps.close();
 			// Update denormalised column in statuses
 			sql = "UPDATE statuses SET deleted = TRUE WHERE messageId = ?";
@@ -1651,13 +1688,11 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public Message getSmallMessage(Connection txn, MessageId m)
+	public Message getMessage(Connection txn, MessageId m) throws DbException {
-			throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT groupId, timestamp, deleted, blockCount"
+			String sql = "SELECT groupId, timestamp, raw FROM messages"
-					+ " FROM messages"
 					+ " WHERE messageId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
@@ -1665,25 +1700,15 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (!rs.next()) throw new DbStateException();
 			GroupId g = new GroupId(rs.getBytes(1));
 			long timestamp = rs.getLong(2);
-			boolean deleted = rs.getBoolean(3);
+			byte[] raw = rs.getBytes(3);
-			int blockCount = rs.getInt(4);
 			if (rs.next()) throw new DbStateException();
 			rs.close();
 			ps.close();
-			if (deleted) throw new MessageDeletedException();
+			if (raw == null) throw new MessageDeletedException();
-			if (blockCount > 1) throw new MessageTooLargeException();
+			if (raw.length <= MESSAGE_HEADER_LENGTH) throw new AssertionError();
-			sql = "SELECT data FROM blocks"
+			byte[] body = new byte[raw.length - MESSAGE_HEADER_LENGTH];
-					+ " WHERE messageId = ? AND blockNumber = 0";
+			System.arraycopy(raw, MESSAGE_HEADER_LENGTH, body, 0, body.length);
-			ps = txn.prepareStatement(sql);
+			return new Message(m, g, timestamp, body);
-			ps.setBytes(1, m.getBytes());
-			rs = ps.executeQuery();
-			if (!rs.next()) throw new DbStateException();
-			byte[] data = rs.getBytes(1);
-			if (data == null) throw new DbStateException();
-			if (rs.next()) throw new DbStateException();
-			rs.close();
-			ps.close();
-			return new Message(m, g, timestamp, data);
 		} catch (SQLException e) {
 			tryToClose(rs, LOG, WARNING);
 			tryToClose(ps, LOG, WARNING);
@@ -2076,28 +2101,17 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public Collection<MessageId> getSmallMessagesToOffer(Connection txn,
+	public Collection<MessageId> getMessagesToRequest(Connection txn,
-			ContactId c, int maxMessages, int maxLatency) throws DbException {
+			ContactId c, int maxMessages) throws DbException {
-		long now = clock.currentTimeMillis();
-		long eta = now + maxLatency;
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT messageId FROM statuses"
+			String sql = "SELECT messageId FROM offers"
-					+ " WHERE contactId = ? AND state = ?"
+					+ " WHERE contactId = ?"
-					+ " AND length <= ?"
+					+ " LIMIT ?";
-					+ " AND groupShared = TRUE AND messageShared = TRUE"
-					+ " AND deleted = FALSE"
-					+ " AND seen = FALSE AND requested = FALSE"
-					+ " AND (expiry <= ? OR eta > ?)"
-					+ " ORDER BY timestamp LIMIT ?";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, c.getInt());
-			ps.setInt(2, DELIVERED.getValue());
+			ps.setInt(2, maxMessages);
-			ps.setInt(3, MESSAGE_HEADER_LENGTH + MAX_BLOCK_LENGTH);
-			ps.setLong(4, now);
-			ps.setLong(5, eta);
-			ps.setInt(6, maxMessages);
 			rs = ps.executeQuery();
 			List<MessageId> ids = new ArrayList<>();
 			while (rs.next()) ids.add(new MessageId(rs.getBytes(1)));
@@ -2150,47 +2164,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
-	@Override
-	public Collection<MessageId> getSmallMessagesToSend(Connection txn,
-			ContactId c, int maxLength, int maxLatency) throws DbException {
-		long now = clock.currentTimeMillis();
-		long eta = now + maxLatency;
-		PreparedStatement ps = null;
-		ResultSet rs = null;
-		try {
-			String sql = "SELECT length, messageId FROM statuses"
-					+ " WHERE contactId = ? AND state = ?"
-					+ " AND length <= ?"
-					+ " AND groupShared = TRUE AND messageShared = TRUE"
-					+ " AND deleted = FALSE"
-					+ " AND seen = FALSE"
-					+ " AND (expiry <= ? OR eta > ?)"
-					+ " ORDER BY timestamp";
-			ps = txn.prepareStatement(sql);
-			ps.setInt(1, c.getInt());
-			ps.setInt(2, DELIVERED.getValue());
-			ps.setInt(3, MESSAGE_HEADER_LENGTH + MAX_BLOCK_LENGTH);
-			ps.setLong(4, now);
-			ps.setLong(5, eta);
-			rs = ps.executeQuery();
-			List<MessageId> ids = new ArrayList<>();
-			int total = 0;
-			while (rs.next()) {
-				int length = rs.getInt(1);
-				if (total + length > maxLength) break;
-				ids.add(new MessageId(rs.getBytes(2)));
-				total += length;
-			}
-			rs.close();
-			ps.close();
-			return ids;
-		} catch (SQLException e) {
-			tryToClose(rs, LOG, WARNING);
-			tryToClose(ps, LOG, WARNING);
-			throw new DbException(e);
-		}
-	}
-
 	@Override
 	public Collection<MessageId> getMessagesToValidate(Connection txn)
 			throws DbException {
@@ -2209,7 +2182,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		ResultSet rs = null;
 		try {
 			String sql = "SELECT messageId FROM messages"
-					+ " WHERE state = ? AND deleted = FALSE";
+					+ " WHERE state = ? AND raw IS NOT NULL";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, state.getValue());
 			rs = ps.executeQuery();
@@ -2914,6 +2887,50 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	private boolean removeOfferedMessage(Connection txn, ContactId c,
+			MessageId m) throws DbException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "DELETE FROM offers"
+					+ " WHERE contactId = ? AND messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			ps.setBytes(2, m.getBytes());
+			int affected = ps.executeUpdate();
+			if (affected < 0 || affected > 1) throw new DbStateException();
+			ps.close();
+			return affected == 1;
+		} catch (SQLException e) {
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
+	@Override
+	public void removeOfferedMessages(Connection txn, ContactId c,
+			Collection<MessageId> requested) throws DbException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "DELETE FROM offers"
+					+ " WHERE contactId = ? AND messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			for (MessageId m : requested) {
+				ps.setBytes(2, m.getBytes());
+				ps.addBatch();
+			}
+			int[] batchAffected = ps.executeBatch();
+			if (batchAffected.length != requested.size())
+				throw new DbStateException();
+			for (int rows : batchAffected)
+				if (rows != 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void removePendingContact(Connection txn, PendingContactId p)
 			throws DbException {

bramble-core/src/main/java/org/briarproject/bramble/db/Migration38_39.java

@@ -37,7 +37,6 @@ class Migration38_39 implements Migration<Connection> {
 			s.execute("ALTER TABLE incomingKeys"
 					+ " ALTER COLUMN contactId"
 					+ " SET NOT NULL");
-			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration39_40.java

@@ -36,7 +36,6 @@ class Migration39_40 implements Migration<Connection> {
 			s.execute("ALTER TABLE statuses"
 					+ " ALTER COLUMN eta"
 					+ " SET NOT NULL");
-			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

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

@@ -38,7 +38,6 @@ class Migration40_41 implements Migration<Connection> {
 			s = txn.createStatement();
 			s.execute("ALTER TABLE contacts"
 					+ dbTypes.replaceTypes(" ADD alias _STRING"));
-			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration41_42.java

@@ -89,7 +89,6 @@ class Migration41_42 implements Migration<Connection> {
 					+ " FOREIGN KEY (keySetId)"
 					+ " REFERENCES outgoingHandshakeKeys (keySetId)"
 					+ " ON DELETE CASCADE)"));
-			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration42_43.java

@@ -44,7 +44,6 @@ class Migration42_43 implements Migration<Connection> {
 					+ " ADD COLUMN handshakePublicKey _BINARY"));
 			s.execute("ALTER TABLE contacts"
 					+ " DROP COLUMN active");
-			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration43_44.java

@@ -50,7 +50,6 @@ class Migration43_44 implements Migration<Connection> {
 					+ " ADD COLUMN rootKey _SECRET"));
 			s.execute("ALTER TABLE outgoingKeys"
 					+ " ADD COLUMN alice BOOLEAN");
-			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration44_45.java

@@ -31,7 +31,6 @@ class Migration44_45 implements Migration<Connection> {
 		try {
 			s = txn.createStatement();
 			s.execute("ALTER TABLE pendingContacts DROP COLUMN state");
-			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration45_46.java

@@ -32,7 +32,6 @@ class Migration45_46 implements Migration<Connection> {
 			s = txn.createStatement();
 			s.execute("ALTER TABLE messages"
 					+ " ADD COLUMN temporary BOOLEAN DEFAULT FALSE NOT NULL");
-			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration46_47.java

@@ -39,7 +39,6 @@ class Migration46_47 implements Migration<Connection> {
 			s.execute(dbTypes.replaceTypes("ALTER TABLE contacts"
 					+ " ADD COLUMN syncVersions"
 					+ " _BINARY DEFAULT '00' NOT NULL"));
-			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration47_48.java

@@ -1,95 +0,0 @@
-package org.briarproject.bramble.db;
-
-import org.briarproject.bramble.api.db.DbException;
-
-import java.sql.Connection;
-import java.sql.PreparedStatement;
-import java.sql.ResultSet;
-import java.sql.SQLException;
-import java.sql.Statement;
-import java.util.logging.Logger;
-
-import static java.lang.System.arraycopy;
-import static java.sql.Types.BINARY;
-import static java.util.logging.Level.INFO;
-import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
-import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
-
-class Migration47_48 implements Migration<Connection> {
-
-	private static final Logger LOG = getLogger(Migration47_48.class.getName());
-
-	private final DatabaseTypes dbTypes;
-
-	Migration47_48(DatabaseTypes dbTypes) {
-		this.dbTypes = dbTypes;
-	}
-
-	@Override
-	public int getStartVersion() {
-		return 47;
-	}
-
-	@Override
-	public int getEndVersion() {
-		return 48;
-	}
-
-	@Override
-	public void migrate(Connection txn) throws DbException {
-		Statement s = null;
-		ResultSet rs = null;
-		PreparedStatement ps = null;
-		try {
-			s = txn.createStatement();
-			s.execute("ALTER TABLE messages"
-					+ " ADD COLUMN deleted BOOLEAN DEFAULT FALSE NOT NULL");
-			s.execute("UPDATE messages SET deleted = TRUE WHERE raw IS NULL");
-			s.execute("ALTER TABLE messages"
-					+ " ADD COLUMN blockCount INT DEFAULT 1 NOT NULL");
-			s.execute(dbTypes.replaceTypes("CREATE TABLE blocks"
-					+ " (messageId _HASH NOT NULL,"
-					+ " blockNumber INT NOT NULL,"
-					+ " blockLength INT NOT NULL," // Excludes block header
-					+ " data BLOB," // Null if message has been deleted
-					+ " PRIMARY KEY (messageId, blockNumber),"
-					+ " FOREIGN KEY (messageId)"
-					+ " REFERENCES messages (messageId)"
-					+ " ON DELETE CASCADE)"));
-			rs = s.executeQuery("SELECT messageId, length, raw FROM messages");
-			ps = txn.prepareStatement("INSERT INTO blocks"
-					+ " (messageId, blockNumber, blockLength, data)"
-					+ " VALUES (?, 0, ?, ?)");
-			int migrated = 0;
-			while (rs.next()) {
-				byte[] id = rs.getBytes(1);
-				int length = rs.getInt(2);
-				byte[] raw = rs.getBytes(3);
-				ps.setBytes(1, id);
-				ps.setInt(2, length - MESSAGE_HEADER_LENGTH);
-				if (raw == null) {
-					ps.setNull(3, BINARY);
-				} else {
-					byte[] data = new byte[raw.length - MESSAGE_HEADER_LENGTH];
-					arraycopy(raw, MESSAGE_HEADER_LENGTH, data, 0, data.length);
-					ps.setBytes(3, data);
-				}
-				if (ps.executeUpdate() != 1) throw new DbStateException();
-				migrated++;
-			}
-			ps.close();
-			rs.close();
-			s.execute("ALTER TABLE messages DROP COLUMN raw");
-			s.close();
-			if (LOG.isLoggable(INFO))
-				LOG.info("Migrated " + migrated + " messages");
-		} catch (SQLException e) {
-			tryToClose(ps, LOG, WARNING);
-			tryToClose(rs, LOG, WARNING);
-			tryToClose(s, LOG, WARNING);
-			throw new DbException(e);
-		}
-	}
-}

bramble-core/src/main/java/org/briarproject/bramble/db/Migration48_49.java

@@ -1,40 +0,0 @@
-package org.briarproject.bramble.db;
-
-import org.briarproject.bramble.api.db.DbException;
-
-import java.sql.Connection;
-import java.sql.SQLException;
-import java.sql.Statement;
-import java.util.logging.Logger;
-
-import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
-
-class Migration48_49 implements Migration<Connection> {
-
-	private static final Logger LOG = getLogger(Migration48_49.class.getName());
-
-	@Override
-	public int getStartVersion() {
-		return 48;
-	}
-
-	@Override
-	public int getEndVersion() {
-		return 49;
-	}
-
-	@Override
-	public void migrate(Connection txn) throws DbException {
-		Statement s = null;
-		try {
-			s = txn.createStatement();
-			s.execute("DROP TABLE offers");
-			s.close();
-		} catch (SQLException e) {
-			tryToClose(s, LOG, WARNING);
-			throw new DbException(e);
-		}
-	}
-}

bramble-core/src/main/java/org/briarproject/bramble/io/TimeoutMonitorImpl.java

@@ -3,15 +3,15 @@ package org.briarproject.bramble.io;
 import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.system.Clock;
-import org.briarproject.bramble.api.system.TaskScheduler;
+import org.briarproject.bramble.api.system.Scheduler;
-import org.briarproject.bramble.api.system.TaskScheduler.Cancellable;
-import org.briarproject.bramble.api.system.Wakeful;
 
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.Executor;
+import java.util.concurrent.Future;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.logging.Logger;
 
 import javax.annotation.concurrent.GuardedBy;
@@ -30,7 +30,7 @@ class TimeoutMonitorImpl implements TimeoutMonitor {
 
 	private static final long CHECK_INTERVAL_MS = SECONDS.toMillis(10);
 
-	private final TaskScheduler scheduler;
+	private final ScheduledExecutorService scheduler;
 	private final Executor ioExecutor;
 	private final Clock clock;
 	private final Object lock = new Object();
@@ -38,10 +38,10 @@ class TimeoutMonitorImpl implements TimeoutMonitor {
 	private final List<TimeoutInputStream> streams = new ArrayList<>();
 
 	@GuardedBy("lock")
-	private Cancellable cancellable = null;
+	private Future<?> task = null;
 
 	@Inject
-	TimeoutMonitorImpl(TaskScheduler scheduler,
+	TimeoutMonitorImpl(@Scheduler ScheduledExecutorService scheduler,
 			@IoExecutor Executor ioExecutor, Clock clock) {
 		this.scheduler = scheduler;
 		this.ioExecutor = ioExecutor;
@@ -55,9 +55,8 @@ class TimeoutMonitorImpl implements TimeoutMonitor {
 				timeoutMs, this::removeStream);
 		synchronized (lock) {
 			if (streams.isEmpty()) {
-				cancellable = scheduler.scheduleWithFixedDelay(
+				task = scheduler.scheduleWithFixedDelay(this::checkTimeouts,
-						this::checkTimeouts, ioExecutor, CHECK_INTERVAL_MS,
+						CHECK_INTERVAL_MS, CHECK_INTERVAL_MS, MILLISECONDS);
-						CHECK_INTERVAL_MS, MILLISECONDS);
 			}
 			streams.add(stream);
 		}
@@ -65,35 +64,33 @@ class TimeoutMonitorImpl implements TimeoutMonitor {
 	}
 
 	private void removeStream(TimeoutInputStream stream) {
-		Cancellable toCancel = null;
+		Future<?> toCancel = null;
 		synchronized (lock) {
 			if (streams.remove(stream) && streams.isEmpty()) {
-				toCancel = cancellable;
+				toCancel = task;
-				cancellable = null;
+				task = null;
 			}
 		}
-		if (toCancel != null) {
+		if (toCancel != null) toCancel.cancel(false);
-			LOG.info("Cancelling timeout monitor task");
-			toCancel.cancel();
-		}
 	}
 
-	@IoExecutor
+	@Scheduler
-	@Wakeful
 	private void checkTimeouts() {
-		List<TimeoutInputStream> snapshot;
+		ioExecutor.execute(() -> {
-		synchronized (lock) {
+			List<TimeoutInputStream> snapshot;
-			snapshot = new ArrayList<>(streams);
+			synchronized (lock) {
-		}
+				snapshot = new ArrayList<>(streams);
-		for (TimeoutInputStream stream : snapshot) {
+			}
-			if (stream.hasTimedOut()) {
+			for (TimeoutInputStream stream : snapshot) {
-				LOG.info("Input stream has timed out");
+				if (stream.hasTimedOut()) {
-				try {
+					LOG.info("Input stream has timed out");
-					stream.close();
+					try {
-				} catch (IOException e) {
+						stream.close();
-					logException(LOG, INFO, e);
+					} catch (IOException e) {
+						logException(LOG, INFO, e);
+					}
 				}
 			}
-		}
+		});
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementConnector.java

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.keyagreement;
 
-import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.crypto.KeyAgreementCrypto;
 import org.briarproject.bramble.api.crypto.KeyPair;
 import org.briarproject.bramble.api.data.BdfList;
@@ -9,8 +8,6 @@ import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.keyagreement.Payload;
 import org.briarproject.bramble.api.keyagreement.TransportDescriptor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.BluetoothConstants;
-import org.briarproject.bramble.api.plugin.LanTcpConstants;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.PluginManager;
 import org.briarproject.bramble.api.plugin.TransportId;
@@ -22,9 +19,7 @@ import org.briarproject.bramble.api.record.RecordWriterFactory;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
 import java.util.concurrent.Callable;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.CountDownLatch;
@@ -33,10 +28,8 @@ import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 
-import static java.util.Arrays.asList;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.CONNECTION_TIMEOUT;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
@@ -48,10 +41,7 @@ class KeyAgreementConnector {
 	}
 
 	private static final Logger LOG =
-			getLogger(KeyAgreementConnector.class.getName());
+			Logger.getLogger(KeyAgreementConnector.class.getName());
-
-	private static final List<TransportId> PREFERRED_TRANSPORTS =
-			asList(BluetoothConstants.ID, LanTcpConstants.ID);
 
 	private final Callbacks callbacks;
 	private final KeyAgreementCrypto keyAgreementCrypto;
@@ -115,35 +105,24 @@ class KeyAgreementConnector {
 		this.alice = alice;
 		aliceLatch.countDown();
 
-		// Start connecting over supported transports in order of preference
+		// Start connecting over supported transports
 		if (LOG.isLoggable(INFO)) {
 			LOG.info("Starting outgoing BQP connections as "
 					+ (alice ? "Alice" : "Bob"));
 		}
-		Map<TransportId, TransportDescriptor> descriptors = new HashMap<>();
 		for (TransportDescriptor d : remotePayload.getTransportDescriptors()) {
-			descriptors.put(d.getId(), d);
+			Plugin p = pluginManager.getPlugin(d.getId());
-		}
+			if (p instanceof DuplexPlugin) {
-		List<Pair<DuplexPlugin, BdfList>> transports = new ArrayList<>();
-		for (TransportId id : PREFERRED_TRANSPORTS) {
-			TransportDescriptor d = descriptors.get(id);
-			Plugin p = pluginManager.getPlugin(id);
-			if (d != null && p instanceof DuplexPlugin) {
 				if (LOG.isLoggable(INFO))
-					LOG.info("Connecting via " + id);
+					LOG.info("Connecting via " + d.getId());
-				transports.add(new Pair<>((DuplexPlugin) p, d.getDescriptor()));
+				DuplexPlugin plugin = (DuplexPlugin) p;
+				byte[] commitment = remotePayload.getCommitment();
+				BdfList descriptor = d.getDescriptor();
+				connectionChooser.submit(new ReadableTask(
+						new ConnectorTask(plugin, commitment, descriptor)));
 			}
 		}
 
-		// TODO: If we don't have any transports in common with the peer,
-		//  warn the user and give up (#1224)
-
-		if (!transports.isEmpty()) {
-			byte[] commitment = remotePayload.getCommitment();
-			connectionChooser.submit(new ReadableTask(new ConnectorTask(
-					transports, commitment)));
-		}
-
 		// Get chosen connection
 		try {
 			KeyAgreementConnection chosen =
@@ -169,13 +148,15 @@ class KeyAgreementConnector {
 
 	private class ConnectorTask implements Callable<KeyAgreementConnection> {
 
-		private final List<Pair<DuplexPlugin, BdfList>> transports;
 		private final byte[] commitment;
+		private final BdfList descriptor;
+		private final DuplexPlugin plugin;
 
-		private ConnectorTask(List<Pair<DuplexPlugin, BdfList>> transports,
+		private ConnectorTask(DuplexPlugin plugin, byte[] commitment,
-				byte[] commitment) {
+				BdfList descriptor) {
-			this.transports = transports;
+			this.plugin = plugin;
 			this.commitment = commitment;
+			this.descriptor = descriptor;
 		}
 
 		@Nullable
@@ -183,18 +164,13 @@ class KeyAgreementConnector {
 		public KeyAgreementConnection call() throws Exception {
 			// Repeat attempts until we connect, get stopped, or get interrupted
 			while (!stopped) {
-				for (Pair<DuplexPlugin, BdfList> pair : transports) {
+				DuplexTransportConnection conn =
-					if (stopped) return null;
+						plugin.createKeyAgreementConnection(commitment,
-					DuplexPlugin plugin = pair.getFirst();
+								descriptor);
-					BdfList descriptor = pair.getSecond();
+				if (conn != null) {
-					DuplexTransportConnection conn =
+					if (LOG.isLoggable(INFO))
-							plugin.createKeyAgreementConnection(commitment,
+						LOG.info(plugin.getId() + ": Outgoing connection");
-									descriptor);
+					return new KeyAgreementConnection(conn, plugin.getId());
-					if (conn != null) {
-						if (LOG.isLoggable(INFO))
-							LOG.info(plugin.getId() + ": Outgoing connection");
-						return new KeyAgreementConnection(conn, plugin.getId());
-					}
 				}
 				// Wait 2s before retry (to circumvent transient failures)
 				Thread.sleep(2000);

bramble-core/src/main/java/org/briarproject/bramble/plugin/BackoffFactoryImpl.java

@@ -1,18 +0,0 @@
-package org.briarproject.bramble.plugin;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.plugin.BackoffFactory;
-
-import javax.annotation.concurrent.Immutable;
-
-@Immutable
-@NotNullByDefault
-class BackoffFactoryImpl implements BackoffFactory {
-
-	@Override
-	public Backoff createBackoff(int minInterval, int maxInterval,
-			double base) {
-		return new BackoffImpl(minInterval, maxInterval, base);
-	}
-}

bramble-core/src/main/java/org/briarproject/bramble/plugin/BackoffImpl.java

@@ -1,42 +0,0 @@
-package org.briarproject.bramble.plugin;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
-
-import java.util.concurrent.atomic.AtomicInteger;
-
-import javax.annotation.concurrent.ThreadSafe;
-
-@ThreadSafe
-@NotNullByDefault
-class BackoffImpl implements Backoff {
-
-	private final int minInterval, maxInterval;
-	private final double base;
-	private final AtomicInteger backoff;
-
-	BackoffImpl(int minInterval, int maxInterval, double base) {
-		this.minInterval = minInterval;
-		this.maxInterval = maxInterval;
-		this.base = base;
-		backoff = new AtomicInteger(0);
-	}
-
-	@Override
-	public int getPollingInterval() {
-		double multiplier = Math.pow(base, backoff.get());
-		// Large or infinite values will be rounded to Integer.MAX_VALUE
-		int interval = (int) (minInterval * multiplier);
-		return Math.min(interval, maxInterval);
-	}
-
-	@Override
-	public void increment() {
-		backoff.incrementAndGet();
-	}
-
-	@Override
-	public void reset() {
-		backoff.set(0);
-	}
-}

bramble-core/src/main/java/org/briarproject/bramble/plugin/PluginManagerImpl.java

@@ -1,7 +1,6 @@
 package org.briarproject.bramble.plugin;
 
 import org.briarproject.bramble.api.connection.ConnectionManager;
-import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
@@ -29,7 +28,6 @@ import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
 import org.briarproject.bramble.api.settings.Settings;
 import org.briarproject.bramble.api.settings.SettingsManager;
-import org.briarproject.bramble.api.system.WakefulIoExecutor;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -46,14 +44,12 @@ import java.util.logging.Logger;
 import javax.annotation.concurrent.ThreadSafe;
 import javax.inject.Inject;
 
-import static java.util.Collections.emptyList;
 import static java.util.logging.Level.FINE;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.plugin.Plugin.PREF_PLUGIN_ENABLE;
 import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
 import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -66,7 +62,7 @@ class PluginManagerImpl implements PluginManager, Service {
 	private static final Logger LOG =
 			getLogger(PluginManagerImpl.class.getName());
 
-	private final Executor ioExecutor, wakefulIoExecutor;
+	private final Executor ioExecutor;
 	private final EventBus eventBus;
 	private final PluginConfig pluginConfig;
 	private final ConnectionManager connectionManager;
@@ -79,15 +75,11 @@ class PluginManagerImpl implements PluginManager, Service {
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
 	@Inject
-	PluginManagerImpl(@IoExecutor Executor ioExecutor,
+	PluginManagerImpl(@IoExecutor Executor ioExecutor, EventBus eventBus,
-			@WakefulIoExecutor Executor wakefulIoExecutor,
+			PluginConfig pluginConfig, ConnectionManager connectionManager,
-			EventBus eventBus,
-			PluginConfig pluginConfig,
-			ConnectionManager connectionManager,
 			SettingsManager settingsManager,
 			TransportPropertyManager transportPropertyManager) {
 		this.ioExecutor = ioExecutor;
-		this.wakefulIoExecutor = wakefulIoExecutor;
 		this.eventBus = eventBus;
 		this.pluginConfig = pluginConfig;
 		this.connectionManager = connectionManager;
@@ -115,7 +107,7 @@ class PluginManagerImpl implements PluginManager, Service {
 				simplexPlugins.add(s);
 				CountDownLatch startLatch = new CountDownLatch(1);
 				startLatches.put(t, startLatch);
-				wakefulIoExecutor.execute(new PluginStarter(s, startLatch));
+				ioExecutor.execute(new PluginStarter(s, startLatch));
 			}
 		}
 		// Instantiate the duplex plugins and start them asynchronously
@@ -131,7 +123,7 @@ class PluginManagerImpl implements PluginManager, Service {
 				duplexPlugins.add(d);
 				CountDownLatch startLatch = new CountDownLatch(1);
 				startLatches.put(t, startLatch);
-				wakefulIoExecutor.execute(new PluginStarter(d, startLatch));
+				ioExecutor.execute(new PluginStarter(d, startLatch));
 			}
 		}
 	}
@@ -143,16 +135,12 @@ class PluginManagerImpl implements PluginManager, Service {
 		LOG.info("Stopping simplex plugins");
 		for (SimplexPlugin s : simplexPlugins) {
 			CountDownLatch startLatch = startLatches.get(s.getId());
-			// Don't need the wakeful executor here as we wait for the plugin
-			// to stop before returning
 			ioExecutor.execute(new PluginStopper(s, startLatch, stopLatch));
 		}
 		// Stop the duplex plugins
 		LOG.info("Stopping duplex plugins");
 		for (DuplexPlugin d : duplexPlugins) {
 			CountDownLatch startLatch = startLatches.get(d.getId());
-			// Don't need the wakeful executor here as we wait for the plugin
-			// to stop before returning
 			ioExecutor.execute(new PluginStopper(d, startLatch, stopLatch));
 		}
 		// Wait for all the plugins to stop
@@ -215,7 +203,7 @@ class PluginManagerImpl implements PluginManager, Service {
 		}
 	}
 
-	private static class PluginStarter implements Runnable {
+	private class PluginStarter implements Runnable {
 
 		private final Plugin plugin;
 		private final CountDownLatch startLatch;
@@ -245,7 +233,7 @@ class PluginManagerImpl implements PluginManager, Service {
 		}
 	}
 
-	private static class PluginStopper implements Runnable {
+	private class PluginStopper implements Runnable {
 
 		private final Plugin plugin;
 		private final CountDownLatch startLatch, stopLatch;
@@ -315,18 +303,6 @@ class PluginManagerImpl implements PluginManager, Service {
 			}
 		}
 
-		@Override
-		public Collection<TransportProperties> getRemoteProperties() {
-			try {
-				Map<ContactId, TransportProperties> remote =
-						transportPropertyManager.getRemoteProperties(id);
-				return remote.values();
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				return emptyList();
-			}
-		}
-
 		@Override
 		public void mergeSettings(Settings s) {
 			PluginManagerImpl.this.mergeSettings(s, id.getString());
@@ -355,10 +331,6 @@ class PluginManagerImpl implements PluginManager, Service {
 				} else if (oldState == ACTIVE) {
 					eventBus.broadcast(new TransportInactiveEvent(id));
 				}
-			} else if (newState == DISABLED) {
-				// Broadcast an event even though the state hasn't changed, as
-				// the reasons for the plugin being disabled may have changed
-				eventBus.broadcast(new TransportStateEvent(id, newState));
 			}
 		}
 

bramble-core/src/main/java/org/briarproject/bramble/plugin/PluginModule.java

@@ -2,7 +2,6 @@ package org.briarproject.bramble.plugin;
 
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.plugin.BackoffFactory;
 import org.briarproject.bramble.api.plugin.PluginConfig;
 import org.briarproject.bramble.api.plugin.PluginManager;
 
@@ -22,11 +21,6 @@ public class PluginModule {
 		Poller poller;
 	}
 
-	@Provides
-	BackoffFactory provideBackoffFactory() {
-		return new BackoffFactoryImpl();
-	}
-
 	@Provides
 	@Singleton
 	PluginManager providePluginManager(LifecycleManager lifecycleManager,

bramble-core/src/main/java/org/briarproject/bramble/plugin/PollerImpl.java

@@ -19,17 +19,13 @@ import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.plugin.event.ConnectionClosedEvent;
-import org.briarproject.bramble.api.plugin.event.ConnectionOpenedEvent;
 import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
 import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
 import org.briarproject.bramble.api.system.Clock;
-import org.briarproject.bramble.api.system.TaskScheduler;
+import org.briarproject.bramble.api.system.Scheduler;
-import org.briarproject.bramble.api.system.TaskScheduler.Cancellable;
-import org.briarproject.bramble.api.system.Wakeful;
-import org.briarproject.bramble.api.system.WakefulIoExecutor;
 
 import java.security.SecureRandom;
 import java.util.ArrayList;
@@ -38,6 +34,8 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.concurrent.Executor;
+import java.util.concurrent.Future;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.logging.Logger;
@@ -58,8 +56,8 @@ class PollerImpl implements Poller, EventListener {
 
 	private static final Logger LOG = getLogger(PollerImpl.class.getName());
 
-	private final Executor ioExecutor, wakefulIoExecutor;
+	private final Executor ioExecutor;
-	private final TaskScheduler scheduler;
+	private final ScheduledExecutorService scheduler;
 	private final ConnectionManager connectionManager;
 	private final ConnectionRegistry connectionRegistry;
 	private final PluginManager pluginManager;
@@ -72,16 +70,12 @@ class PollerImpl implements Poller, EventListener {
 
 	@Inject
 	PollerImpl(@IoExecutor Executor ioExecutor,
-			@WakefulIoExecutor Executor wakefulIoExecutor,
+			@Scheduler ScheduledExecutorService scheduler,
-			TaskScheduler scheduler,
 			ConnectionManager connectionManager,
-			ConnectionRegistry connectionRegistry,
+			ConnectionRegistry connectionRegistry, PluginManager pluginManager,
-			PluginManager pluginManager,
 			TransportPropertyManager transportPropertyManager,
-			SecureRandom random,
+			SecureRandom random, Clock clock) {
-			Clock clock) {
 		this.ioExecutor = ioExecutor;
-		this.wakefulIoExecutor = wakefulIoExecutor;
 		this.scheduler = scheduler;
 		this.connectionManager = connectionManager;
 		this.connectionRegistry = connectionRegistry;
@@ -101,16 +95,10 @@ class PollerImpl implements Poller, EventListener {
 			connectToContact(c.getContactId());
 		} else if (e instanceof ConnectionClosedEvent) {
 			ConnectionClosedEvent c = (ConnectionClosedEvent) e;
-			// Reschedule polling, the polling interval may have decreased
-			reschedule(c.getTransportId());
 			// If an outgoing connection failed, try to reconnect
 			if (!c.isIncoming() && c.isException()) {
 				connectToContact(c.getContactId(), c.getTransportId());
 			}
-		} else if (e instanceof ConnectionOpenedEvent) {
-			ConnectionOpenedEvent c = (ConnectionOpenedEvent) e;
-			// Reschedule polling, the polling interval may have decreased
-			reschedule(c.getTransportId());
 		} else if (e instanceof TransportActiveEvent) {
 			TransportActiveEvent t = (TransportActiveEvent) e;
 			// Poll the newly activated transport
@@ -138,7 +126,7 @@ class PollerImpl implements Poller, EventListener {
 	}
 
 	private void connectToContact(ContactId c, SimplexPlugin p) {
-		wakefulIoExecutor.execute(() -> {
+		ioExecutor.execute(() -> {
 			TransportId t = p.getId();
 			if (connectionRegistry.isConnected(c, t)) return;
 			try {
@@ -154,7 +142,7 @@ class PollerImpl implements Poller, EventListener {
 	}
 
 	private void connectToContact(ContactId c, DuplexPlugin p) {
-		wakefulIoExecutor.execute(() -> {
+		ioExecutor.execute(() -> {
 			TransportId t = p.getId();
 			if (connectionRegistry.isConnected(c, t)) return;
 			try {
@@ -169,12 +157,6 @@ class PollerImpl implements Poller, EventListener {
 		});
 	}
 
-	private void reschedule(TransportId t) {
-		Plugin p = pluginManager.getPlugin(t);
-		if (p != null && p.shouldPoll())
-			schedule(p, p.getPollingInterval(), false);
-	}
-
 	private void pollNow(TransportId t) {
 		Plugin p = pluginManager.getPlugin(t);
 		// Randomise next polling interval
@@ -191,11 +173,11 @@ class PollerImpl implements Poller, EventListener {
 			if (scheduled == null || due < scheduled.task.due) {
 				// If a later task exists, cancel it. If it's already started
 				// it will abort safely when it finds it's been replaced
-				if (scheduled != null) scheduled.cancellable.cancel();
+				if (scheduled != null) scheduled.future.cancel(false);
 				PollTask task = new PollTask(p, due, randomiseNext);
-				Cancellable cancellable = scheduler.schedule(task, ioExecutor,
+				Future future = scheduler.schedule(() ->
-						delay, MILLISECONDS);
+						ioExecutor.execute(task), delay, MILLISECONDS);
-				tasks.put(t, new ScheduledPollTask(task, cancellable));
+				tasks.put(t, new ScheduledPollTask(task, future));
 			}
 		} finally {
 			lock.unlock();
@@ -206,7 +188,7 @@ class PollerImpl implements Poller, EventListener {
 		lock.lock();
 		try {
 			ScheduledPollTask scheduled = tasks.remove(t);
-			if (scheduled != null) scheduled.cancellable.cancel();
+			if (scheduled != null) scheduled.future.cancel(false);
 		} finally {
 			lock.unlock();
 		}
@@ -237,11 +219,11 @@ class PollerImpl implements Poller, EventListener {
 	private class ScheduledPollTask {
 
 		private final PollTask task;
-		private final Cancellable cancellable;
+		private final Future future;
 
-		private ScheduledPollTask(PollTask task, Cancellable cancellable) {
+		private ScheduledPollTask(PollTask task, Future future) {
 			this.task = task;
-			this.cancellable = cancellable;
+			this.future = future;
 		}
 	}
 
@@ -259,7 +241,6 @@ class PollerImpl implements Poller, EventListener {
 
 		@Override
 		@IoExecutor
-		@Wakeful
 		public void run() {
 			lock.lock();
 			try {

bramble-core/src/main/java/org/briarproject/bramble/plugin/bluetooth/BluetoothConnectionFactory.java

@@ -1,14 +0,0 @@
-package org.briarproject.bramble.plugin.bluetooth;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
-import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-
-import java.io.IOException;
-
-@NotNullByDefault
-interface BluetoothConnectionFactory<S> {
-
-	DuplexTransportConnection wrapSocket(DuplexPlugin plugin, S socket)
-			throws IOException;
-}

bramble-core/src/main/java/org/briarproject/bramble/plugin/bluetooth/BluetoothPlugin.java

@@ -1,11 +1,11 @@
 package org.briarproject.bramble.plugin.bluetooth;
 
 import org.briarproject.bramble.api.FormatException;
-import org.briarproject.bramble.api.Multiset;
 import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementListeningEvent;
@@ -14,15 +14,16 @@ import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.ConnectionHandler;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.PluginException;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.plugin.event.BluetoothEnabledEvent;
+import org.briarproject.bramble.api.plugin.event.DisableBluetoothEvent;
+import org.briarproject.bramble.api.plugin.event.EnableBluetoothEvent;
 import org.briarproject.bramble.api.properties.TransportProperties;
-import org.briarproject.bramble.api.properties.event.RemoteTransportPropertiesUpdatedEvent;
 import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
 import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
 import org.briarproject.bramble.api.settings.Settings;
@@ -44,12 +45,8 @@ import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.TRANSPORT_ID_BLUETOOTH;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.DEFAULT_PREF_ADDRESS_IS_REFLECTED;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.DEFAULT_PREF_EVER_CONNECTED;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.DEFAULT_PREF_PLUGIN_ENABLE;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.PREF_ADDRESS_IS_REFLECTED;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.PREF_EVER_CONNECTED;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_ADDRESS;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_UUID;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.UUID_BYTES;
@@ -57,7 +54,6 @@ import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
 import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
 import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
 import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
-import static org.briarproject.bramble.api.properties.TransportPropertyConstants.REFLECTED_PROPERTY_PREFIX;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
@@ -66,21 +62,19 @@ import static org.briarproject.bramble.util.StringUtils.macToString;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
+abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 
 	private static final Logger LOG =
 			getLogger(BluetoothPlugin.class.getName());
 
 	final BluetoothConnectionLimiter connectionLimiter;
-	final BluetoothConnectionFactory<S> connectionFactory;
+	final TimeoutMonitor timeoutMonitor;
 
-	private final Executor ioExecutor, wakefulIoExecutor;
+	private final Executor ioExecutor;
 	private final SecureRandom secureRandom;
-	private final Backoff backoff;
 	private final PluginCallback callback;
-	private final int maxLatency, maxIdleTime;
+	private final int maxLatency, maxIdleTime, pollingInterval;
 	private final AtomicBoolean used = new AtomicBoolean(false);
-	private final AtomicBoolean everConnected = new AtomicBoolean(false);
 
 	protected final PluginState state = new PluginState();
 
@@ -90,6 +84,12 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 
 	abstract boolean isAdapterEnabled();
 
+	abstract void enableAdapter();
+
+	abstract void disableAdapterIfEnabledByUs();
+
+	abstract void setEnabledByUs();
+
 	/**
 	 * Returns the local Bluetooth address, or null if no valid address can
 	 * be found.
@@ -113,23 +113,17 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 	abstract DuplexTransportConnection discoverAndConnect(String uuid);
 
 	BluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
-			BluetoothConnectionFactory<S> connectionFactory,
+			TimeoutMonitor timeoutMonitor, Executor ioExecutor,
-			Executor ioExecutor,
+			SecureRandom secureRandom, PluginCallback callback, int maxLatency, int maxIdleTime,
-			Executor wakefulIoExecutor,
+			int pollingInterval) {
-			SecureRandom secureRandom,
-			Backoff backoff,
-			PluginCallback callback,
-			int maxLatency,
-			int maxIdleTime) {
 		this.connectionLimiter = connectionLimiter;
-		this.connectionFactory = connectionFactory;
+		this.timeoutMonitor = timeoutMonitor;
 		this.ioExecutor = ioExecutor;
-		this.wakefulIoExecutor = wakefulIoExecutor;
 		this.secureRandom = secureRandom;
-		this.backoff = backoff;
 		this.callback = callback;
 		this.maxLatency = maxLatency;
 		this.maxIdleTime = maxIdleTime;
+		this.pollingInterval = pollingInterval;
 	}
 
 	void onAdapterEnabled() {
@@ -171,8 +165,6 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 		Settings settings = callback.getSettings();
 		boolean enabledByUser = settings.getBoolean(PREF_PLUGIN_ENABLE,
 				DEFAULT_PREF_PLUGIN_ENABLE);
-		everConnected.set(settings.getBoolean(PREF_EVER_CONNECTED,
-				DEFAULT_PREF_EVER_CONNECTED));
 		state.setStarted(enabledByUser);
 		try {
 			initialiseAdapter();
@@ -180,7 +172,10 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 			throw new PluginException(e);
 		}
 		updateProperties();
-		if (enabledByUser && isAdapterEnabled()) bind();
+		if (enabledByUser) {
+			if (isAdapterEnabled()) bind();
+			else enableAdapter();
+		}
 	}
 
 	private void bind() {
@@ -199,7 +194,6 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 				tryToClose(ss);
 				return;
 			}
-			backoff.reset();
 			acceptContactConnections(ss);
 		});
 	}
@@ -208,68 +202,25 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 		TransportProperties p = callback.getLocalProperties();
 		String address = p.get(PROP_ADDRESS);
 		String uuid = p.get(PROP_UUID);
-		Settings s = callback.getSettings();
-		boolean isReflected = s.getBoolean(PREF_ADDRESS_IS_REFLECTED,
-				DEFAULT_PREF_ADDRESS_IS_REFLECTED);
 		boolean changed = false;
-		if (address == null || isReflected) {
+		if (address == null) {
 			address = getBluetoothAddress();
-			if (LOG.isLoggable(INFO)) {
+			if (LOG.isLoggable(INFO))
 				LOG.info("Local address " + scrubMacAddress(address));
-			}
+			if (!isNullOrEmpty(address)) {
-			if (address == null) {
+				p.put(PROP_ADDRESS, address);
-				if (everConnected.get()) {
-					address = getReflectedAddress();
-					if (LOG.isLoggable(INFO)) {
-						LOG.info("Reflected address " +
-								scrubMacAddress(address));
-					}
-					if (address != null) {
-						changed = true;
-						isReflected = true;
-					}
-				}
-			} else {
 				changed = true;
-				isReflected = false;
 			}
 		}
 		if (uuid == null) {
 			byte[] random = new byte[UUID_BYTES];
 			secureRandom.nextBytes(random);
 			uuid = UUID.nameUUIDFromBytes(random).toString();
+			p.put(PROP_UUID, uuid);
 			changed = true;
 		}
 		contactConnectionsUuid = uuid;
-		if (changed) {
+		if (changed) callback.mergeLocalProperties(p);
-			p = new TransportProperties();
-			// If we previously used a reflected address and there's no longer
-			// a reflected address with enough votes to be used, we'll continue
-			// to use the old reflected address until there's a new winner
-			if (address != null) p.put(PROP_ADDRESS, address);
-			p.put(PROP_UUID, uuid);
-			callback.mergeLocalProperties(p);
-			s = new Settings();
-			s.putBoolean(PREF_ADDRESS_IS_REFLECTED, isReflected);
-			callback.mergeSettings(s);
-		}
-	}
-
-	@Nullable
-	private String getReflectedAddress() {
-		// Count the number of votes for each reflected address
-		String key = REFLECTED_PROPERTY_PREFIX + PROP_ADDRESS;
-		Multiset<String> votes = new Multiset<>();
-		for (TransportProperties p : callback.getRemoteProperties()) {
-			String address = p.get(key);
-			if (address != null && isValidAddress(address)) votes.add(address);
-		}
-		// If an address gets more than half of the votes, accept it
-		int total = votes.getTotal();
-		for (String address : votes.keySet()) {
-			if (votes.getCount(address) * 2 > total) return address;
-		}
-		return null;
 	}
 
 	private void acceptContactConnections(SS ss) {
@@ -285,28 +236,15 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 			}
 			LOG.info("Connection received");
 			connectionLimiter.connectionOpened(conn);
-			backoff.reset();
-			setEverConnected();
 			callback.handleConnection(conn);
 		}
 	}
 
-	private void setEverConnected() {
-		if (!everConnected.getAndSet(true)) {
-			ioExecutor.execute(() -> {
-				Settings s = new Settings();
-				s.putBoolean(PREF_EVER_CONNECTED, true);
-				callback.mergeSettings(s);
-				// Contacts may already have sent a reflected address
-				updateProperties();
-			});
-		}
-	}
-
 	@Override
 	public void stop() {
 		SS ss = state.setStopped();
 		tryToClose(ss);
+		disableAdapterIfEnabledByUs();
 	}
 
 	@Override
@@ -326,14 +264,13 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 
 	@Override
 	public int getPollingInterval() {
-		return backoff.getPollingInterval();
+		return pollingInterval;
 	}
 
 	@Override
 	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
 			properties) {
 		if (getState() != ACTIVE) return;
-		backoff.increment();
 		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
 			connect(p.getFirst(), p.getSecond());
 		}
@@ -344,13 +281,9 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 		if (isNullOrEmpty(address)) return;
 		String uuid = p.get(PROP_UUID);
 		if (isNullOrEmpty(uuid)) return;
-		wakefulIoExecutor.execute(() -> {
+		ioExecutor.execute(() -> {
 			DuplexTransportConnection d = createConnection(p);
-			if (d != null) {
+			if (d != null) h.handleConnection(d);
-				backoff.reset();
-				setEverConnected();
-				h.handleConnection(d);
-			}
 		});
 	}
 
@@ -436,10 +369,8 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
 		DuplexTransportConnection conn;
 		if (descriptor.size() == 1) {
-			if (LOG.isLoggable(INFO)) {
+			if (LOG.isLoggable(INFO))
-				LOG.info("Discovering address for key agreement UUID " +
+				LOG.info("Discovering address for key agreement UUID " + uuid);
-						uuid);
-			}
 			conn = discoverAndConnect(uuid);
 		} else {
 			String address;
@@ -453,10 +384,7 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 				LOG.info("Connecting to key agreement UUID " + uuid);
 			conn = connect(address, uuid);
 		}
-		if (conn != null) {
+		if (conn != null) connectionLimiter.connectionOpened(conn);
-			connectionLimiter.connectionOpened(conn);
-			setEverConnected();
-		}
 		return conn;
 	}
 
@@ -479,7 +407,13 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 
 	@Override
 	public void eventOccurred(Event e) {
-		if (e instanceof SettingsUpdatedEvent) {
+		if (e instanceof EnableBluetoothEvent) {
+			ioExecutor.execute(this::enableAdapter);
+		} else if (e instanceof DisableBluetoothEvent) {
+			ioExecutor.execute(this::disableAdapterIfEnabledByUs);
+		} else if (e instanceof BluetoothEnabledEvent) {
+			setEnabledByUs();
+		} else if (e instanceof SettingsUpdatedEvent) {
 			SettingsUpdatedEvent s = (SettingsUpdatedEvent) e;
 			if (s.getNamespace().equals(ID.getString()))
 				ioExecutor.execute(() -> onSettingsUpdated(s.getSettings()));
@@ -487,12 +421,6 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 			ioExecutor.execute(connectionLimiter::keyAgreementStarted);
 		} else if (e instanceof KeyAgreementStoppedListeningEvent) {
 			ioExecutor.execute(connectionLimiter::keyAgreementEnded);
-		} else if (e instanceof RemoteTransportPropertiesUpdatedEvent) {
-			RemoteTransportPropertiesUpdatedEvent r =
-					(RemoteTransportPropertiesUpdatedEvent) e;
-			if (r.getTransportId().equals(ID)) {
-				ioExecutor.execute(this::updateProperties);
-			}
 		}
 	}
 
@@ -505,13 +433,11 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 		if (ss != null) {
 			LOG.info("Disabled by user, closing server socket");
 			tryToClose(ss);
+			disableAdapterIfEnabledByUs();
 		} else if (s == INACTIVE) {
-			if (isAdapterEnabled()) {
+			LOG.info("Enabled by user, opening server socket");
-				LOG.info("Enabled by user, opening server socket");
+			if (isAdapterEnabled()) bind();
-				bind();
+			else enableAdapter();
-			} else {
-				LOG.info("Enabled by user but adapter is disabled");
-			}
 		}
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/LanTcpPlugin.java

@@ -5,7 +5,6 @@ import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
@@ -88,15 +87,10 @@ class LanTcpPlugin extends TcpPlugin {
 		}
 	}
 
-	LanTcpPlugin(Executor ioExecutor,
+	LanTcpPlugin(Executor ioExecutor, PluginCallback callback, int maxLatency,
-			Executor wakefulIoExecutor,
+			int maxIdleTime, int pollingInterval, int connectionTimeout) {
-			Backoff backoff,
+		super(ioExecutor, callback, maxLatency, maxIdleTime, pollingInterval,
-			PluginCallback callback,
+				connectionTimeout);
-			int maxLatency,
-			int maxIdleTime,
-			int connectionTimeout) {
-		super(ioExecutor, wakefulIoExecutor, backoff, callback, maxLatency,
-				maxIdleTime, connectionTimeout);
 	}
 
 	@Override
@@ -354,7 +348,7 @@ class LanTcpPlugin extends TcpPlugin {
 				tryToClose(ss, LOG, WARNING);
 			}
 		}
-		if (ss == null || !ss.isBound()) {
+		if (ss == null) {
 			LOG.info("Could not bind server socket for key agreement");
 			return null;
 		}

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/LanTcpPluginFactory.java

@@ -1,47 +1,35 @@
 package org.briarproject.bramble.plugin.tcp;
 
 import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.plugin.BackoffFactory;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
-import org.briarproject.bramble.api.system.WakefulIoExecutor;
 
 import java.util.concurrent.Executor;
 
 import javax.annotation.concurrent.Immutable;
-import javax.inject.Inject;
 
+import static java.util.concurrent.TimeUnit.MINUTES;
+import static java.util.concurrent.TimeUnit.SECONDS;
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.ID;
 
 @Immutable
 @NotNullByDefault
 public class LanTcpPluginFactory implements DuplexPluginFactory {
 
-	private static final int MAX_LATENCY = 30_000; // 30 seconds
+	private static final int MAX_LATENCY = (int) SECONDS.toMillis(30);
-	private static final int MAX_IDLE_TIME = 30_000; // 30 seconds
+	private static final int MAX_IDLE_TIME = (int) SECONDS.toMillis(30);
-	private static final int CONNECTION_TIMEOUT = 3_000; // 3 seconds
+	private static final int POLLING_INTERVAL = (int) MINUTES.toMillis(1);
-	private static final int MIN_POLLING_INTERVAL = 60_000; // 1 minute
+	private static final int CONNECTION_TIMEOUT = (int) SECONDS.toMillis(3);
-	private static final int MAX_POLLING_INTERVAL = 600_000; // 10 mins
-	private static final double BACKOFF_BASE = 1.2;
 
-	private final Executor ioExecutor, wakefulIoExecutor;
+	private final Executor ioExecutor;
 	private final EventBus eventBus;
-	private final BackoffFactory backoffFactory;
 
-	@Inject
+	public LanTcpPluginFactory(Executor ioExecutor, EventBus eventBus) {
-	public LanTcpPluginFactory(@IoExecutor Executor ioExecutor,
-			@WakefulIoExecutor Executor wakefulIoExecutor,
-			EventBus eventBus,
-			BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
-		this.wakefulIoExecutor = wakefulIoExecutor;
 		this.eventBus = eventBus;
-		this.backoffFactory = backoffFactory;
 	}
 
 	@Override
@@ -56,10 +44,8 @@ public class LanTcpPluginFactory implements DuplexPluginFactory {
 
 	@Override
 	public DuplexPlugin createPlugin(PluginCallback callback) {
-		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
+		LanTcpPlugin plugin = new LanTcpPlugin(ioExecutor, callback,
-				MAX_POLLING_INTERVAL, BACKOFF_BASE);
+				MAX_LATENCY, MAX_IDLE_TIME, POLLING_INTERVAL,
-		LanTcpPlugin plugin = new LanTcpPlugin(ioExecutor, wakefulIoExecutor,
-				backoff, callback, MAX_LATENCY, MAX_IDLE_TIME,
 				CONNECTION_TIMEOUT);
 		eventBus.addListener(plugin);
 		return plugin;

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/TcpPlugin.java

@@ -10,7 +10,6 @@ import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.ConnectionHandler;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
@@ -66,10 +65,9 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 	private static final Pattern DOTTED_QUAD =
 			Pattern.compile("^\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}$");
 
-	protected final Executor ioExecutor, wakefulIoExecutor, bindExecutor;
+	protected final Executor ioExecutor, bindExecutor;
-	protected final Backoff backoff;
 	protected final PluginCallback callback;
-	protected final int maxLatency, maxIdleTime;
+	protected final int maxLatency, maxIdleTime, pollingInterval;
 	protected final int connectionTimeout, socketTimeout;
 	protected final AtomicBoolean used = new AtomicBoolean(false);
 	protected final PluginState state = new PluginState();
@@ -107,19 +105,13 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 	 */
 	protected abstract boolean isEnabledByDefault();
 
-	TcpPlugin(Executor ioExecutor,
+	TcpPlugin(Executor ioExecutor, PluginCallback callback, int maxLatency,
-			Executor wakefulIoExecutor,
+			int maxIdleTime, int pollingInterval, int connectionTimeout) {
-			Backoff backoff,
-			PluginCallback callback,
-			int maxLatency,
-			int maxIdleTime,
-			int connectionTimeout) {
 		this.ioExecutor = ioExecutor;
-		this.wakefulIoExecutor = wakefulIoExecutor;
-		this.backoff = backoff;
 		this.callback = callback;
 		this.maxLatency = maxLatency;
 		this.maxIdleTime = maxIdleTime;
+		this.pollingInterval = pollingInterval;
 		this.connectionTimeout = connectionTimeout;
 		if (maxIdleTime > Integer.MAX_VALUE / 2)
 			socketTimeout = Integer.MAX_VALUE;
@@ -149,21 +141,15 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 
 	protected void bind() {
 		bindExecutor.execute(() -> {
-			State s = getState();
+			if (getState() != INACTIVE) return;
-			if (s != ACTIVE && s != INACTIVE) return;
 			bind(true);
 			bind(false);
 		});
 	}
 
 	private void bind(boolean ipv4) {
-		ServerSocket old = state.getServerSocket(ipv4);
 		ServerSocket ss = null;
 		for (InetSocketAddress addr : getLocalSocketAddresses(ipv4)) {
-			if (old != null && addr.equals(old.getLocalSocketAddress())) {
-				LOG.info("Server socket already bound");
-				return;
-			}
 			try {
 				ss = new ServerSocket();
 				ss.bind(addr);
@@ -174,7 +160,7 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 				tryToClose(ss, LOG, WARNING);
 			}
 		}
-		if (ss == null || !ss.isBound()) {
+		if (ss == null) {
 			LOG.info("Could not bind server socket");
 			return;
 		}
@@ -183,7 +169,6 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 			tryToClose(ss, LOG, WARNING);
 			return;
 		}
-		backoff.reset();
 		InetSocketAddress local =
 				(InetSocketAddress) ss.getLocalSocketAddress();
 		setLocalSocketAddress(local, ipv4);
@@ -216,7 +201,6 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 				LOG.info("Connection from " +
 						scrubSocketAddress(s.getRemoteSocketAddress()));
 			}
-			backoff.reset();
 			callback.handleConnection(new TcpTransportConnection(this, s));
 		}
 	}
@@ -243,26 +227,22 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 
 	@Override
 	public int getPollingInterval() {
-		return backoff.getPollingInterval();
+		return pollingInterval;
 	}
 
 	@Override
 	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
 			properties) {
 		if (getState() != ACTIVE) return;
-		backoff.increment();
 		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
 			connect(p.getFirst(), p.getSecond());
 		}
 	}
 
 	private void connect(TransportProperties p, ConnectionHandler h) {
-		wakefulIoExecutor.execute(() -> {
+		ioExecutor.execute(() -> {
 			DuplexTransportConnection d = createConnection(p);
-			if (d != null) {
+			if (d != null) h.handleConnection(d);
-				backoff.reset();
-				h.handleConnection(d);
-			}
 		});
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/WanTcpPlugin.java

@@ -2,7 +2,6 @@ package org.briarproject.bramble.plugin.tcp;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.properties.TransportProperties;
@@ -30,16 +29,11 @@ class WanTcpPlugin extends TcpPlugin {
 
 	private volatile MappingResult mappingResult;
 
-	WanTcpPlugin(Executor ioExecutor,
+	WanTcpPlugin(Executor ioExecutor, PortMapper portMapper,
-			Executor wakefulIoExecutor,
+			PluginCallback callback, int maxLatency, int maxIdleTime,
-			Backoff backoff,
+			int pollingInterval, int connectionTimeout) {
-			PortMapper portMapper,
+		super(ioExecutor, callback, maxLatency, maxIdleTime, pollingInterval,
-			PluginCallback callback,
+				connectionTimeout);
-			int maxLatency,
-			int maxIdleTime,
-			int connectionTimeout) {
-		super(ioExecutor, wakefulIoExecutor, backoff, callback, maxLatency,
-				maxIdleTime, connectionTimeout);
 		this.portMapper = portMapper;
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/WanTcpPluginFactory.java

@@ -1,50 +1,38 @@
 package org.briarproject.bramble.plugin.tcp;
 
 import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.lifecycle.ShutdownManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.plugin.BackoffFactory;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
-import org.briarproject.bramble.api.system.WakefulIoExecutor;
 
 import java.util.concurrent.Executor;
 
 import javax.annotation.concurrent.Immutable;
-import javax.inject.Inject;
 
+import static java.util.concurrent.TimeUnit.MINUTES;
+import static java.util.concurrent.TimeUnit.SECONDS;
 import static org.briarproject.bramble.api.plugin.WanTcpConstants.ID;
 
 @Immutable
 @NotNullByDefault
 public class WanTcpPluginFactory implements DuplexPluginFactory {
 
-	private static final int MAX_LATENCY = 30_000; // 30 seconds
+	private static final int MAX_LATENCY = (int) SECONDS.toMillis(30);
-	private static final int MAX_IDLE_TIME = 30_000; // 30 seconds
+	private static final int MAX_IDLE_TIME = (int) SECONDS.toMillis(30);
-	private static final int CONNECTION_TIMEOUT = 30_000; // 30 seconds
+	private static final int POLLING_INTERVAL = (int) MINUTES.toMillis(1);
-	private static final int MIN_POLLING_INTERVAL = 60_000; // 1 minute
+	private static final int CONNECTION_TIMEOUT = (int) SECONDS.toMillis(30);
-	private static final int MAX_POLLING_INTERVAL = 600_000; // 10 mins
-	private static final double BACKOFF_BASE = 1.2;
 
-	private final Executor ioExecutor, wakefulIoExecutor;
+	private final Executor ioExecutor;
 	private final EventBus eventBus;
-	private final BackoffFactory backoffFactory;
 	private final ShutdownManager shutdownManager;
 
-	@Inject
+	public WanTcpPluginFactory(Executor ioExecutor, EventBus eventBus,
-	public WanTcpPluginFactory(@IoExecutor Executor ioExecutor,
-			@WakefulIoExecutor Executor wakefulIoExecutor,
-			EventBus eventBus,
-			BackoffFactory backoffFactory,
 			ShutdownManager shutdownManager) {
 		this.ioExecutor = ioExecutor;
-		this.wakefulIoExecutor = wakefulIoExecutor;
 		this.eventBus = eventBus;
-		this.backoffFactory = backoffFactory;
 		this.shutdownManager = shutdownManager;
 	}
 
@@ -60,12 +48,9 @@ public class WanTcpPluginFactory implements DuplexPluginFactory {
 
 	@Override
 	public DuplexPlugin createPlugin(PluginCallback callback) {
-		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
+		WanTcpPlugin plugin = new WanTcpPlugin(ioExecutor,
-				MAX_POLLING_INTERVAL, BACKOFF_BASE);
+				new PortMapperImpl(shutdownManager), callback, MAX_LATENCY,
-		PortMapper portMapper = new PortMapperImpl(shutdownManager);
+				MAX_IDLE_TIME, POLLING_INTERVAL, CONNECTION_TIMEOUT);
-		WanTcpPlugin plugin = new WanTcpPlugin(ioExecutor, wakefulIoExecutor,
-				backoff, portMapper, callback, MAX_LATENCY, MAX_IDLE_TIME,
-				CONNECTION_TIMEOUT);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -17,7 +17,6 @@ import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.ConnectionHandler;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.PluginException;
@@ -46,9 +45,11 @@ import java.net.ServerSocket;
 import java.net.Socket;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Scanner;
+import java.util.Set;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
@@ -109,30 +110,60 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	private static final Logger LOG = getLogger(TorPlugin.class.getName());
 
+	/**
+	 * Controller events we want to receive.
+	 */
 	private static final String[] EVENTS = {
 			"CIRC", "ORCONN", "HS_DESC", "NOTICE", "WARN", "ERR"
 	};
+
+	/**
+	 * Command-line argument to set our process as Tor's owning controller
+	 * so Tor exits when our process dies.
+	 */
 	private static final String OWNER = "__OwningControllerProcess";
+
+	/**
+	 * How long to wait for the authentication cookie file to be created.
+	 */
 	private static final int COOKIE_TIMEOUT_MS = 3000;
+
+	/**
+	 * How often to check whether the authentication cookie file has been
+	 * created.
+	 */
 	private static final int COOKIE_POLLING_INTERVAL_MS = 200;
+
+	/**
+	 * Regex for matching v2 hidden service names.
+	 */
 	private static final Pattern ONION_V2 = Pattern.compile("[a-z2-7]{16}");
+
+	/**
+	 * Regex for matching v3 hidden service names.
+	 */
 	private static final Pattern ONION_V3 = Pattern.compile("[a-z2-7]{56}");
 
-	private final Executor ioExecutor, wakefulIoExecutor;
+	/**
-	private final Executor connectionStatusExecutor;
+	 * How many copies of our descriptor must be uploaded before we consider
+	 * our hidden service to be reachable and switch to less frequent polling.
+	 */
+	private static final int MIN_DESCRIPTORS_UPLOADED = 5;
+
+	private final Executor ioExecutor, connectionStatusExecutor;
 	private final NetworkManager networkManager;
 	private final LocationUtils locationUtils;
 	private final SocketFactory torSocketFactory;
 	private final Clock clock;
 	private final BatteryManager batteryManager;
-	private final Backoff backoff;
 	private final TorRendezvousCrypto torRendezvousCrypto;
 	private final PluginCallback callback;
 	private final String architecture;
 	private final CircumventionProvider circumventionProvider;
 	private final ResourceProvider resourceProvider;
 	private final int maxLatency, maxIdleTime, socketTimeout;
-	private final File torDirectory, geoIpFile, configFile;
+	private final int initialPollingInterval, stablePollingInterval;
+	private final File torDirectory, torFile, geoIpFile, obfs4File, configFile;
 	private final File doneFile, cookieFile;
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
@@ -146,24 +177,16 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	protected abstract long getLastUpdateTime();
 
-	TorPlugin(Executor ioExecutor,
+	TorPlugin(Executor ioExecutor, NetworkManager networkManager,
-			Executor wakefulIoExecutor,
+			LocationUtils locationUtils, SocketFactory torSocketFactory,
-			NetworkManager networkManager,
+			Clock clock, ResourceProvider resourceProvider,
-			LocationUtils locationUtils,
-			SocketFactory torSocketFactory,
-			Clock clock,
-			ResourceProvider resourceProvider,
 			CircumventionProvider circumventionProvider,
 			BatteryManager batteryManager,
-			Backoff backoff,
 			TorRendezvousCrypto torRendezvousCrypto,
-			PluginCallback callback,
+			PluginCallback callback, String architecture, int maxLatency,
-			String architecture,
+			int maxIdleTime, int initialPollingInterval,
-			int maxLatency,
+			int stablePollingInterval, File torDirectory) {
-			int maxIdleTime,
-			File torDirectory) {
 		this.ioExecutor = ioExecutor;
-		this.wakefulIoExecutor = wakefulIoExecutor;
 		this.networkManager = networkManager;
 		this.locationUtils = locationUtils;
 		this.torSocketFactory = torSocketFactory;
@@ -171,7 +194,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		this.resourceProvider = resourceProvider;
 		this.circumventionProvider = circumventionProvider;
 		this.batteryManager = batteryManager;
-		this.backoff = backoff;
 		this.torRendezvousCrypto = torRendezvousCrypto;
 		this.callback = callback;
 		this.architecture = architecture;
@@ -180,8 +202,12 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		if (maxIdleTime > Integer.MAX_VALUE / 2)
 			socketTimeout = Integer.MAX_VALUE;
 		else socketTimeout = maxIdleTime * 2;
+		this.initialPollingInterval = initialPollingInterval;
+		this.stablePollingInterval = stablePollingInterval;
 		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");
@@ -190,14 +216,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				new PoliteExecutor("TorPlugin", ioExecutor, 1);
 	}
 
-	protected File getTorExecutableFile() {
-		return new File(torDirectory, "tor");
-	}
-
-	protected File getObfs4ExecutableFile() {
-		return new File(torDirectory, "obfs4proxy");
-	}
-
 	@Override
 	public TransportId getId() {
 		return TorConstants.ID;
@@ -230,7 +248,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			LOG.warning("Old auth cookie not deleted");
 		// Start a new Tor process
 		LOG.info("Starting Tor");
-		File torFile = getTorExecutableFile();
 		String torPath = torFile.getAbsolutePath();
 		String configPath = configFile.getAbsolutePath();
 		String pid = String.valueOf(getProcessId());
@@ -329,43 +346,44 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void installAssets() throws PluginException {
+		InputStream in = null;
+		OutputStream out = null;
 		try {
 			// The done file may already exist from a previous installation
 			//noinspection ResultOfMethodCallIgnored
 			doneFile.delete();
-			installTorExecutable();
+			// Unzip the Tor binary to the filesystem
-			installObfs4Executable();
+			in = getTorInputStream();
-			extract(getGeoIpInputStream(), geoIpFile);
+			out = new FileOutputStream(torFile);
-			extract(getConfigInputStream(), configFile);
+			copyAndClose(in, out);
+			// Make the Tor binary executable
+			if (!torFile.setExecutable(true, true)) throw new IOException();
+			// Unzip the GeoIP database to the filesystem
+			in = getGeoIpInputStream();
+			out = new FileOutputStream(geoIpFile);
+			copyAndClose(in, out);
+			// Unzip the Obfs4 proxy to the filesystem
+			in = getObfs4InputStream();
+			out = new FileOutputStream(obfs4File);
+			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);
+			copyAndClose(in, out);
 			if (!doneFile.createNewFile())
 				LOG.warning("Failed to create done file");
 		} catch (IOException e) {
+			tryToClose(in, LOG, WARNING);
+			tryToClose(out, LOG, WARNING);
 			throw new PluginException(e);
 		}
 	}
 
-	protected void extract(InputStream in, File dest) throws IOException {
+	private InputStream getTorInputStream() throws IOException {
-		OutputStream out = new FileOutputStream(dest);
-		copyAndClose(in, out);
-	}
-
-	protected void installTorExecutable() throws IOException {
 		if (LOG.isLoggable(INFO))
 			LOG.info("Installing Tor binary for " + architecture);
-		File torFile = getTorExecutableFile();
-		extract(getTorInputStream(), torFile);
-		if (!torFile.setExecutable(true, true)) throw new IOException();
-	}
-
-	protected void installObfs4Executable() throws IOException {
-		if (LOG.isLoggable(INFO))
-			LOG.info("Installing obfs4proxy binary for " + architecture);
-		File obfs4File = getObfs4ExecutableFile();
-		extract(getObfs4InputStream(), obfs4File);
-		if (!obfs4File.setExecutable(true, true)) throw new IOException();
-	}
-
-	private InputStream getTorInputStream() throws IOException {
 		InputStream in = resourceProvider
 				.getResourceInputStream("tor_" + architecture, ".zip");
 		ZipInputStream zin = new ZipInputStream(in);
@@ -382,6 +400,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	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);
@@ -448,7 +468,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			callback.mergeSettings(s);
 			// Create a hidden service if necessary
 			ioExecutor.execute(() -> publishHiddenService(localPort));
-			backoff.reset();
 			// Accept incoming hidden service connections from Tor
 			acceptContactConnections(ss);
 		});
@@ -466,7 +485,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		// in the migration period since first publishing it
 		if (!isNullOrEmpty(privKey2)) {
 			long now = clock.currentTimeMillis();
-			long then = v3Created == null ? now : Long.parseLong(v3Created);
+			long then = v3Created == null ? now : Long.valueOf(v3Created);
 			if (now - then >= V3_MIGRATION_PERIOD_MS) retireV2HiddenService();
 			else publishV2HiddenService(port, privKey2);
 		}
@@ -528,15 +547,15 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			LOG.warning("Tor did not return a private key");
 			return;
 		}
+		// Publish the hidden service's onion hostname in transport properties
 		String onion3 = response.get(HS_ADDRESS);
 		if (LOG.isLoggable(INFO)) {
 			LOG.info("V3 hidden service " + scrubOnion(onion3));
 		}
+		TransportProperties p = new TransportProperties();
+		p.put(PROP_ONION_V3, onion3);
+		callback.mergeLocalProperties(p);
 		if (privKey == null) {
-			// Publish the hidden service's onion hostname in transport props
-			TransportProperties p = new TransportProperties();
-			p.put(PROP_ONION_V3, onion3);
-			callback.mergeLocalProperties(p);
 			// Save the hidden service's private key for next time
 			Settings s = new Settings();
 			s.put(HS_PRIVATE_KEY_V3, response.get(HS_PRIVKEY));
@@ -558,7 +577,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				return;
 			}
 			LOG.info("Connection received");
-			backoff.reset();
 			callback.handleConnection(new TorTransportConnection(this, s));
 		}
 	}
@@ -573,7 +591,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		if (enable) {
 			Collection<String> conf = new ArrayList<>();
 			conf.add("UseBridges 1");
-			File obfs4File = getObfs4ExecutableFile();
 			if (needsMeek) {
 				conf.add("ClientTransportPlugin meek_lite exec " +
 						obfs4File.getAbsolutePath());
@@ -621,26 +638,28 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public int getPollingInterval() {
-		return backoff.getPollingInterval();
+		if (state.isDescriptorPublished()) {
+			LOG.info("Using stable polling interval");
+			return stablePollingInterval;
+		} else {
+			LOG.info("Using initial polling interval");
+			return initialPollingInterval;
+		}
 	}
 
 	@Override
 	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
 			properties) {
 		if (getState() != ACTIVE) return;
-		backoff.increment();
 		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
 			connect(p.getFirst(), p.getSecond());
 		}
 	}
 
 	private void connect(TransportProperties p, ConnectionHandler h) {
-		wakefulIoExecutor.execute(() -> {
+		ioExecutor.execute(() -> {
 			DuplexTransportConnection d = createConnection(p);
-			if (d != null) {
+			if (d != null) h.handleConnection(d);
-				backoff.reset();
-				h.handleConnection(d);
-			}
 		});
 	}
 
@@ -770,10 +789,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public void circuitStatus(String status, String id, String path) {
-		if (status.equals("BUILT") &&
+		if (status.equals("BUILT") && state.getAndSetCircuitBuilt()) {
-				state.getAndSetCircuitBuilt()) {
 			LOG.info("First circuit built");
-			backoff.reset();
 		}
 	}
 
@@ -783,8 +800,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public void orConnStatus(String status, String orName) {
-		if (LOG.isLoggable(INFO))
+		if (LOG.isLoggable(INFO)) LOG.info("OR connection " + status);
-			LOG.info("OR connection " + status + " " + orName);
+		state.setOrConnectionStatus(orName, status);
 		if (status.equals("CLOSED") || status.equals("FAILED")) {
 			// Check whether we've lost connectivity
 			updateConnectionStatus(networkManager.getNetworkStatus(),
@@ -805,20 +822,18 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		if (LOG.isLoggable(INFO)) LOG.info(severity + " " + msg);
 		if (severity.equals("NOTICE") && msg.startsWith("Bootstrapped 100%")) {
 			state.setBootstrapped();
-			backoff.reset();
 		}
 	}
 
 	@Override
 	public void unrecognized(String type, String msg) {
 		if (type.equals("HS_DESC") && msg.startsWith("UPLOADED")) {
-			if (LOG.isLoggable(INFO)) {
+			String[] words = msg.split(" ");
-				String[] words = msg.split(" ");
+			if (words.length > 1 && ONION_V3.matcher(words[1]).matches()) {
-				if (words.length > 1 && ONION_V3.matcher(words[1]).matches()) {
+				LOG.info("V3 descriptor uploaded");
-					LOG.info("V3 descriptor uploaded");
+				state.descriptorUploaded();
-				} else {
+			} else {
-					LOG.info("V2 descriptor uploaded");
+				LOG.info("V2 descriptor uploaded");
-				}
 			}
 		}
 	}
@@ -974,6 +989,12 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		@Nullable
 		private ServerSocket serverSocket = null;
 
+		@GuardedBy("this")
+		private final Set<String> orConnections = new HashSet<>();
+
+		@GuardedBy("this")
+		private int descriptorsUploaded = 0;
+
 		synchronized void setStarted() {
 			started = true;
 			callback.pluginStateChanged(getState());
@@ -1007,7 +1028,10 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		synchronized void enableNetwork(boolean enable) {
 			networkInitialised = true;
 			networkEnabled = enable;
-			if (!enable) circuitBuilt = false;
+			if (!enable) {
+				circuitBuilt = false;
+				descriptorsUploaded = 0;
+			}
 			callback.pluginStateChanged(getState());
 		}
 
@@ -1017,6 +1041,34 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			callback.pluginStateChanged(getState());
 		}
 
+		synchronized void setOrConnectionStatus(String orName, String status) {
+			if (status.equals("CONNECTED")) {
+				if (!orConnections.add(orName)) {
+					LOG.warning("Duplicate OR connection");
+				}
+			} else {
+				orConnections.remove(orName);
+				if (orConnections.isEmpty()) descriptorsUploaded = 0;
+			}
+			if (LOG.isLoggable(INFO)) {
+				LOG.info(orConnections.size() + " OR connections");
+			}
+			callback.pluginStateChanged(getState());
+		}
+
+		// Doesn't affect getState()
+		synchronized void descriptorUploaded() {
+			if (networkEnabled && !orConnections.isEmpty()) {
+				descriptorsUploaded++;
+			} else {
+				LOG.warning("Descriptor was uploaded with no OR connection");
+			}
+		}
+
+		synchronized boolean isDescriptorPublished() {
+			return descriptorsUploaded >= MIN_DESCRIPTORS_UPLOADED;
+		}
+
 		// Doesn't affect getState()
 		synchronized boolean setServerSocket(ServerSocket ss) {
 			if (stopped || serverSocket != null) return false;
@@ -1036,7 +1088,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			if (reasonsDisabled != 0) return DISABLED;
 			if (!networkInitialised) return ENABLING;
 			if (!networkEnabled) return INACTIVE;
-			return bootstrapped && circuitBuilt ? ACTIVE : ENABLING;
+			return bootstrapped && circuitBuilt && !orConnections.isEmpty()
+					? ACTIVE : ENABLING;
 		}
 
 		synchronized int getReasonsDisabled() {

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

@@ -18,7 +18,6 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
-import org.briarproject.bramble.api.properties.event.RemoteTransportPropertiesUpdatedEvent;
 import org.briarproject.bramble.api.sync.Group;
 import org.briarproject.bramble.api.sync.Group.Visibility;
 import org.briarproject.bramble.api.sync.GroupId;
@@ -43,7 +42,6 @@ import static org.briarproject.bramble.api.properties.TransportPropertyConstants
 import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MSG_KEY_LOCAL;
 import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MSG_KEY_TRANSPORT_ID;
 import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MSG_KEY_VERSION;
-import static org.briarproject.bramble.api.properties.TransportPropertyConstants.REFLECTED_PROPERTY_PREFIX;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 
 @Immutable
@@ -131,10 +129,8 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 					// We've already received a newer update - delete this one
 					db.deleteMessage(txn, m.getId());
 					db.deleteMessageMetadata(txn, m.getId());
-					return false;
 				}
 			}
-			txn.attach(new RemoteTransportPropertiesUpdatedEvent(t));
 		} catch (FormatException e) {
 			throw new InvalidMessageException(e);
 		}
@@ -157,27 +153,15 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 		if (props.isEmpty()) return;
 		try {
 			db.transaction(false, txn -> {
-				Contact contact = db.getContact(txn, c);
+				Group g = getContactGroup(db.getContact(txn, c));
-				Group g = getContactGroup(contact);
 				BdfDictionary meta = clientHelper.getGroupMetadataAsDictionary(
 						txn, g.getId());
 				BdfDictionary discovered =
 						meta.getOptionalDictionary(GROUP_KEY_DISCOVERED);
-				BdfDictionary merged;
+				if (discovered == null) discovered = new BdfDictionary();
-				boolean changed;
+				discovered.putAll(props);
-				if (discovered == null) {
+				meta.put(GROUP_KEY_DISCOVERED, discovered);
-					merged = new BdfDictionary(props);
+				clientHelper.mergeGroupMetadata(txn, g.getId(), meta);
-					changed = true;
-				} else {
-					merged = new BdfDictionary(discovered);
-					merged.putAll(props);
-					changed = !merged.equals(discovered);
-				}
-				if (changed) {
-					meta.put(GROUP_KEY_DISCOVERED, merged);
-					clientHelper.mergeGroupMetadata(txn, g.getId(), meta);
-					updateLocalProperties(txn, contact, t);
-				}
 			});
 		} catch (FormatException e) {
 			throw new DbException(e);
@@ -199,7 +183,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 			Map<TransportId, LatestUpdate> latest = findLatestLocal(txn);
 			// Retrieve and parse the latest local properties
 			for (Entry<TransportId, LatestUpdate> e : latest.entrySet()) {
-				BdfList message = clientHelper.getSmallMessageAsList(txn,
+				BdfList message = clientHelper.getMessageAsList(txn,
 						e.getValue().messageId);
 				local.put(e.getKey(), parseProperties(message));
 			}
@@ -220,7 +204,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 						true);
 				if (latest != null) {
 					// Retrieve and parse the latest local properties
-					BdfList message = clientHelper.getSmallMessageAsList(txn,
+					BdfList message = clientHelper.getMessageAsList(txn,
 							latest.messageId);
 					p = parseProperties(message);
 				}
@@ -242,24 +226,6 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 		});
 	}
 
-	private void updateLocalProperties(Transaction txn, Contact c,
-			TransportId t) throws DbException {
-		try {
-			TransportProperties local;
-			LatestUpdate latest = findLatest(txn, localGroup.getId(), t, true);
-			if (latest == null) {
-				local = new TransportProperties();
-			} else {
-				BdfList message = clientHelper.getSmallMessageAsList(txn,
-						latest.messageId);
-				local = parseProperties(message);
-			}
-			storeLocalProperties(txn, c, t, local);
-		} catch (FormatException e) {
-			throw new DbException(e);
-		}
-	}
-
 	private TransportProperties getRemoteProperties(Transaction txn, Contact c,
 			TransportId t) throws DbException {
 		Group g = getContactGroup(c);
@@ -271,8 +237,8 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 				remote = new TransportProperties();
 			} else {
 				// Retrieve and parse the latest remote properties
-				BdfList message = clientHelper.getSmallMessageAsList(txn,
+				BdfList message =
-						latest.messageId);
+						clientHelper.getMessageAsList(txn, latest.messageId);
 				remote = parseProperties(message);
 			}
 			// Merge in any discovered properties
@@ -315,7 +281,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 					}
 					changed = true;
 				} else {
-					BdfList message = clientHelper.getSmallMessageAsList(txn,
+					BdfList message = clientHelper.getMessageAsList(txn,
 							latest.messageId);
 					TransportProperties old = parseProperties(message);
 					merged = new TransportProperties(old);
@@ -332,10 +298,18 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 					storeMessage(txn, localGroup.getId(), t, merged, version,
 							true, false);
 					// Delete the previous update, if any
-					if (latest != null) db.removeMessage(txn, latest.messageId);
+					if (latest != null)
+						db.removeMessage(txn, latest.messageId);
 					// Store the merged properties in each contact's group
 					for (Contact c : db.getContacts(txn)) {
-						storeLocalProperties(txn, c, t, merged);
+						Group g = getContactGroup(c);
+						latest = findLatest(txn, g.getId(), t, true);
+						version = latest == null ? 1 : latest.version + 1;
+						storeMessage(txn, g.getId(), t, merged, version,
+								true, true);
+						// Delete the previous update, if any
+						if (latest != null)
+							db.removeMessage(txn, latest.messageId);
 					}
 				}
 			});
@@ -344,34 +318,6 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 		}
 	}
 
-	private void storeLocalProperties(Transaction txn, Contact c,
-			TransportId t, TransportProperties p)
-			throws DbException, FormatException {
-		Group g = getContactGroup(c);
-		LatestUpdate latest = findLatest(txn, g.getId(), t, true);
-		long version = latest == null ? 1 : latest.version + 1;
-		// Reflect any remote properties we've discovered
-		BdfDictionary meta = clientHelper.getGroupMetadataAsDictionary(txn,
-				g.getId());
-		BdfDictionary discovered =
-				meta.getOptionalDictionary(GROUP_KEY_DISCOVERED);
-		TransportProperties combined;
-		if (discovered == null) {
-			combined = p;
-		} else {
-			combined = new TransportProperties(p);
-			TransportProperties d = clientHelper
-					.parseAndValidateTransportProperties(discovered);
-			for (Entry<String, String> e : d.entrySet()) {
-				String key = REFLECTED_PROPERTY_PREFIX + e.getKey();
-				combined.put(key, e.getValue());
-			}
-		}
-		storeMessage(txn, g.getId(), t, combined, version, true, true);
-		// Delete the previous update, if any
-		if (latest != null) db.removeMessage(txn, latest.messageId);
-	}
-
 	private Group getContactGroup(Contact c) {
 		return contactGroupFactory.createContactGroup(CLIENT_ID,
 				MAJOR_VERSION, c);

bramble-core/src/main/java/org/briarproject/bramble/rendezvous/RendezvousPollerImpl.java

@@ -41,9 +41,7 @@ import org.briarproject.bramble.api.rendezvous.event.RendezvousConnectionClosedE
 import org.briarproject.bramble.api.rendezvous.event.RendezvousConnectionOpenedEvent;
 import org.briarproject.bramble.api.rendezvous.event.RendezvousPollEvent;
 import org.briarproject.bramble.api.system.Clock;
-import org.briarproject.bramble.api.system.TaskScheduler;
+import org.briarproject.bramble.api.system.Scheduler;
-import org.briarproject.bramble.api.system.TaskScheduler.Cancellable;
-import org.briarproject.bramble.api.system.Wakeful;
 
 import java.security.GeneralSecurityException;
 import java.util.ArrayList;
@@ -54,6 +52,7 @@ import java.util.Map;
 import java.util.Map.Entry;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Executor;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
 
@@ -69,7 +68,6 @@ import static org.briarproject.bramble.api.contact.PendingContactState.ADDING_CO
 import static org.briarproject.bramble.api.contact.PendingContactState.FAILED;
 import static org.briarproject.bramble.api.contact.PendingContactState.OFFLINE;
 import static org.briarproject.bramble.api.contact.PendingContactState.WAITING_FOR_CONNECTION;
-import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNull;
 import static org.briarproject.bramble.rendezvous.RendezvousConstants.POLLING_INTERVAL_MS;
 import static org.briarproject.bramble.rendezvous.RendezvousConstants.RENDEZVOUS_TIMEOUT_MS;
@@ -82,7 +80,7 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 	private static final Logger LOG =
 			getLogger(RendezvousPollerImpl.class.getName());
 
-	private final TaskScheduler scheduler;
+	private final ScheduledExecutorService scheduler;
 	private final DatabaseComponent db;
 	private final IdentityManager identityManager;
 	private final TransportCrypto transportCrypto;
@@ -104,12 +102,10 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 			new HashMap<>();
 	@Nullable
 	private KeyPair handshakeKeyPair = null;
-	@Nullable
-	private Cancellable pollTask = null;
 
 	@Inject
 	RendezvousPollerImpl(@IoExecutor Executor ioExecutor,
-			TaskScheduler scheduler,
+			@Scheduler ScheduledExecutorService scheduler,
 			DatabaseComponent db,
 			IdentityManager identityManager,
 			TransportCrypto transportCrypto,
@@ -148,6 +144,8 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 		} catch (DbException e) {
 			throw new ServiceException(e);
 		}
+		scheduler.scheduleAtFixedRate(this::poll, POLLING_INTERVAL_MS,
+				POLLING_INTERVAL_MS, MILLISECONDS);
 	}
 
 	@EventExecutor
@@ -188,12 +186,6 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 			}
 			if (cs.numEndpoints == 0) broadcastState(p.getId(), OFFLINE);
 			else broadcastState(p.getId(), WAITING_FOR_CONNECTION);
-			if (cryptoStates.size() == 1) {
-				LOG.info("Starting poller");
-				requireNull(pollTask);
-				pollTask = scheduler.scheduleWithFixedDelay(this::poll, worker,
-						POLLING_INTERVAL_MS, POLLING_INTERVAL_MS, MILLISECONDS);
-			}
 		} catch (DbException | GeneralSecurityException e) {
 			logException(LOG, WARNING, e);
 		}
@@ -213,12 +205,12 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 		return plugin.createRendezvousEndpoint(k, cs.alice, h);
 	}
 
-	// Worker
+	@Scheduler
-	@Wakeful
 	private void poll() {
-		LOG.info("Polling");
+		worker.execute(() -> {
-		removeExpiredPendingContacts();
+			removeExpiredPendingContacts();
-		for (PluginState ps : pluginStates.values()) poll(ps);
+			for (PluginState ps : pluginStates.values()) poll(ps);
+		});
 	}
 
 	// Worker
@@ -243,15 +235,9 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 			RendezvousEndpoint endpoint = ps.endpoints.remove(p);
 			if (endpoint != null) tryToClose(endpoint, LOG, INFO);
 		}
-		if (cryptoStates.isEmpty()) {
-			LOG.info("Stopping poller");
-			requireNonNull(pollTask).cancel();
-			pollTask = null;
-		}
 	}
 
 	// Worker
-	@Wakeful
 	private void poll(PluginState ps) {
 		if (ps.endpoints.isEmpty()) return;
 		TransportId t = ps.plugin.getId();

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

@@ -15,7 +15,6 @@ import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
 import org.briarproject.bramble.api.sync.Ack;
 import org.briarproject.bramble.api.sync.Message;
-import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Priority;
 import org.briarproject.bramble.api.sync.Request;
@@ -26,8 +25,8 @@ import org.briarproject.bramble.api.sync.event.CloseSyncConnectionsEvent;
 import org.briarproject.bramble.api.sync.event.GroupVisibilityUpdatedEvent;
 import org.briarproject.bramble.api.sync.event.MessageRequestedEvent;
 import org.briarproject.bramble.api.sync.event.MessageSharedEvent;
-import org.briarproject.bramble.api.sync.event.MessagesToAckEvent;
+import org.briarproject.bramble.api.sync.event.MessageToAckEvent;
-import org.briarproject.bramble.api.sync.event.MessagesToRequestEvent;
+import org.briarproject.bramble.api.sync.event.MessageToRequestEvent;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.transport.StreamWriter;
 
@@ -88,6 +87,8 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 	private final AtomicBoolean generateAckQueued = new AtomicBoolean(false);
 	private final AtomicBoolean generateBatchQueued = new AtomicBoolean(false);
 	private final AtomicBoolean generateOfferQueued = new AtomicBoolean(false);
+	private final AtomicBoolean generateRequestQueued =
+			new AtomicBoolean(false);
 	private final AtomicLong nextSendTime = new AtomicLong(Long.MAX_VALUE);
 
 	private volatile boolean interrupted = false;
@@ -124,6 +125,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			generateAck();
 			generateBatch();
 			generateOffer();
+			generateRequest();
 			long now = clock.currentTimeMillis();
 			long nextKeepalive = now + maxIdleTime;
 			boolean dataToFlush = true;
@@ -195,6 +197,11 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			dbExecutor.execute(new GenerateOffer());
 	}
 
+	private void generateRequest() {
+		if (generateRequestQueued.compareAndSet(false, true))
+			dbExecutor.execute(new GenerateRequest());
+	}
+
 	private void setNextSendTime(long time) {
 		long old = nextSendTime.getAndSet(time);
 		if (time < old) writerTasks.add(NEXT_SEND_TIME_DECREASED);
@@ -220,16 +227,12 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 		} else if (e instanceof MessageRequestedEvent) {
 			if (((MessageRequestedEvent) e).getContactId().equals(contactId))
 				generateBatch();
-		} else if (e instanceof MessagesToAckEvent) {
+		} else if (e instanceof MessageToAckEvent) {
-			if (((MessagesToAckEvent) e).getContactId().equals(contactId))
+			if (((MessageToAckEvent) e).getContactId().equals(contactId))
 				generateAck();
-		} else if (e instanceof MessagesToRequestEvent) {
+		} else if (e instanceof MessageToRequestEvent) {
-			MessagesToRequestEvent m = (MessagesToRequestEvent) e;
+			if (((MessageToRequestEvent) e).getContactId().equals(contactId))
-			if (m.getContactId().equals(contactId)) {
+				generateRequest();
-				Collection<MessageId> ids = m.consumeIds();
-				if (ids != null)
-					writerTasks.add(new WriteRequest(new Request(ids)));
-			}
 		} else if (e instanceof LifecycleEvent) {
 			LifecycleEvent l = (LifecycleEvent) e;
 			if (l.getLifecycleState() == STOPPING) interrupt();
@@ -337,7 +340,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			try {
 				Offer o = db.transactionWithNullableResult(false, txn -> {
 					Offer offer = db.generateOffer(txn, contactId,
-							MAX_MESSAGE_IDS, maxLatency, true);
+							MAX_MESSAGE_IDS, maxLatency);
 					setNextSendTime(db.getNextSendTime(txn, contactId));
 					return offer;
 				});
@@ -369,6 +372,27 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 		}
 	}
 
+	private class GenerateRequest implements Runnable {
+
+		@DatabaseExecutor
+		@Override
+		public void run() {
+			if (interrupted) return;
+			if (!generateRequestQueued.getAndSet(false))
+				throw new AssertionError();
+			try {
+				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));
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				interrupt();
+			}
+		}
+	}
+
 	private class WriteRequest implements ThrowingRunnable<IOException> {
 
 		private final Request request;
@@ -383,6 +407,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (interrupted) return;
 			recordWriter.writeRequest(request);
 			LOG.info("Sent request");
+			generateRequest();
 		}
 	}
 }

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

@@ -186,8 +186,7 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 				Collection<Message> b =
 						db.transactionWithNullableResult(false, txn ->
 								db.generateBatch(txn, contactId,
-										MAX_RECORD_PAYLOAD_BYTES, maxLatency,
+										MAX_RECORD_PAYLOAD_BYTES, maxLatency));
-										true));
 				if (LOG.isLoggable(INFO))
 					LOG.info("Generated batch: " + (b != null));
 				if (b == null) decrementOutstandingQueries();

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

@@ -120,7 +120,7 @@ class ValidationManagerImpl implements ValidationManager, Service,
 			Pair<Message, Group> mg = db.transactionWithResult(true, txn -> {
 				MessageId id = unvalidated.poll();
 				if (id == null) throw new AssertionError();
-				Message m = db.getSmallMessage(txn, id);
+				Message m = db.getMessage(txn, id);
 				Group g = db.getGroup(txn, m.getGroupId());
 				return new Pair<>(m, g);
 			});
@@ -179,7 +179,7 @@ class ValidationManagerImpl implements ValidationManager, Service,
 						invalidateMessage(txn, id);
 						addDependentsToInvalidate(txn, id, invalidate);
 					} else if (allDelivered) {
-						Message m = db.getSmallMessage(txn, id);
+						Message m = db.getMessage(txn, id);
 						Group g = db.getGroup(txn, m.getGroupId());
 						ClientId c = g.getClientId();
 						int majorVersion = g.getMajorVersion();