Add wakeful IO executor.

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

@@ -7,6 +7,7 @@ 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;
 
@@ -15,6 +16,7 @@ import dagger.Module;
 		AndroidNetworkModule.class,
 		AndroidSystemModule.class,
 		AndroidTaskSchedulerModule.class,
+		AndroidWakefulIoExecutorModule.class,
 		CircumventionModule.class,
 		ReportingModule.class,
 		SocksModule.class

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

@@ -0,0 +1,23 @@
+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-api/src/main/java/org/briarproject/bramble/api/system/WakefulIoExecutor.java

@@ -0,0 +1,26 @@
+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/system/DefaultWakefulIoExecutorModule.java

@@ -0,0 +1,23 @@
+package org.briarproject.bramble.system;
+
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.system.WakefulIoExecutor;
+
+import java.util.concurrent.Executor;
+
+import dagger.Module;
+import dagger.Provides;
+
+/**
+ * Provides a default implementation of {@link WakefulIoExecutor} for systems
+ * without wake locks.
+ */
+@Module
+public class DefaultWakefulIoExecutorModule {
+
+	@Provides
+	@WakefulIoExecutor
+	Executor provideWakefulIoExecutor(@IoExecutor Executor ioExecutor) {
+		return ioExecutor;
+	}
+}

briar-headless/src/main/java/org/briarproject/briar/headless/HeadlessModule.kt

@@ -26,6 +26,7 @@ import org.briarproject.bramble.plugin.tor.CircumventionProvider
 import org.briarproject.bramble.plugin.tor.UnixTorPluginFactory
 import org.briarproject.bramble.socks.SocksModule
 import org.briarproject.bramble.system.DefaultTaskSchedulerModule
+import org.briarproject.bramble.system.DefaultWakefulIoExecutorModule
 import org.briarproject.bramble.system.DesktopSecureRandomModule
 import org.briarproject.bramble.system.JavaSystemModule
 import org.briarproject.bramble.util.OsUtils.isLinux
@@ -48,6 +49,7 @@ import javax.net.SocketFactory
         DefaultBatteryManagerModule::class,
         DefaultEventExecutorModule::class,
         DefaultTaskSchedulerModule::class,
+        DefaultWakefulIoExecutorModule::class,
         DesktopSecureRandomModule::class,
         HeadlessBlogModule::class,
         HeadlessContactModule::class,

briar-headless/src/test/java/org/briarproject/briar/headless/HeadlessTestModule.kt

@@ -15,6 +15,7 @@ import org.briarproject.bramble.network.JavaNetworkModule
 import org.briarproject.bramble.plugin.tor.CircumventionModule
 import org.briarproject.bramble.socks.SocksModule
 import org.briarproject.bramble.system.DefaultTaskSchedulerModule
+import org.briarproject.bramble.system.DefaultWakefulIoExecutorModule
 import org.briarproject.bramble.system.JavaSystemModule
 import org.briarproject.bramble.test.TestSecureRandomModule
 import org.briarproject.briar.headless.blogs.HeadlessBlogModule
@@ -34,6 +35,7 @@ import javax.inject.Singleton
         CircumventionModule::class,
         DefaultEventExecutorModule::class,
         DefaultTaskSchedulerModule::class,
+        DefaultWakefulIoExecutorModule::class,
         SocksModule::class,
         TestSecureRandomModule::class,
         HeadlessBlogModule::class,