Remove unused parameter.

This should reduce the impact of connections that fail at the remote
end.

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

@@ -67,7 +67,7 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 	@Override
 	public DuplexPlugin createPlugin(PluginCallback callback) {
 		BluetoothConnectionLimiter connectionLimiter =
-				new BluetoothConnectionLimiterImpl(eventBus);
+				new BluetoothConnectionLimiterImpl(eventBus, clock);
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidBluetoothPlugin plugin = new AndroidBluetoothPlugin(

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

@@ -3,9 +3,16 @@ package org.briarproject.bramble.plugin.bluetooth;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 
+import static java.util.concurrent.TimeUnit.SECONDS;
+
 @NotNullByDefault
 interface BluetoothConnectionLimiter {
 
+	/**
+	 * How long a connection must remain open before it's considered stable.
+	 */
+	long STABILITY_PERIOD_MS = SECONDS.toMillis(90);
+
 	/**
 	 * Informs the limiter that key agreement has started.
 	 */

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

@@ -4,7 +4,9 @@ import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.sync.event.CloseSyncConnectionsEvent;
+import org.briarproject.bramble.api.system.Clock;
 
+import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.logging.Logger;
@@ -24,16 +26,19 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 			getLogger(BluetoothConnectionLimiterImpl.class.getName());
 
 	private final EventBus eventBus;
+	private final Clock clock;
 
 	private final Object lock = new Object();
 	@GuardedBy("lock")
-	private final List<DuplexTransportConnection> connections =
+	private final List<ConnectionRecord> connections = new LinkedList<>();
-			new LinkedList<>();
 	@GuardedBy("lock")
 	private boolean keyAgreementInProgress = false;
+	@GuardedBy("lock")
+	private int connectionLimit = 2;
 
-	BluetoothConnectionLimiterImpl(EventBus eventBus) {
+	BluetoothConnectionLimiterImpl(EventBus eventBus, Clock clock) {
 		this.eventBus = eventBus;
+		this.clock = clock;
 	}
 
 	@Override
@@ -59,9 +64,15 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 			if (keyAgreementInProgress) {
 				LOG.info("Can't open contact connection during key agreement");
 				return false;
-			} else {
+			}
+			long now = clock.currentTimeMillis();
+			countStableConnections(now);
+			if (connections.size() < connectionLimit) {
 				LOG.info("Can open contact connection");
 				return true;
+			} else {
+				LOG.info("Can't open contact connection due to limit");
+				return false;
 			}
 		}
 	}
@@ -69,7 +80,9 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 	@Override
 	public void connectionOpened(DuplexTransportConnection conn) {
 		synchronized (lock) {
-			connections.add(conn);
+			long now = clock.currentTimeMillis();
+			countStableConnections(now);
+			connections.add(new ConnectionRecord(conn, now));
 			if (LOG.isLoggable(INFO)) {
 				LOG.info("Connection opened, " + connections.size() + " open");
 			}
@@ -79,7 +92,14 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 	@Override
 	public void connectionClosed(DuplexTransportConnection conn) {
 		synchronized (lock) {
-			connections.remove(conn);
+			countStableConnections(clock.currentTimeMillis());
+			Iterator<ConnectionRecord> it = connections.iterator();
+			while (it.hasNext()) {
+				if (it.next().conn == conn) {
+					it.remove();
+					break;
+				}
+			}
 			if (LOG.isLoggable(INFO)) {
 				LOG.info("Connection closed, " + connections.size() + " open");
 			}
@@ -89,8 +109,36 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 	@Override
 	public void allConnectionsClosed() {
 		synchronized (lock) {
+			long now = clock.currentTimeMillis();
+			countStableConnections(now);
 			connections.clear();
 			LOG.info("All connections closed");
 		}
 	}
+
+	@GuardedBy("lock")
+	private void countStableConnections(long now) {
+		int stable = 0;
+		for (ConnectionRecord rec : connections) {
+			if (now - rec.timeOpened >= STABILITY_PERIOD_MS) stable++;
+		}
+		if (stable > connectionLimit) {
+			connectionLimit = stable;
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Raising connection limit to " + connectionLimit);
+			}
+		}
+	}
+
+	private static class ConnectionRecord {
+
+		private final DuplexTransportConnection conn;
+		private final long timeOpened;
+
+		private ConnectionRecord(DuplexTransportConnection conn,
+				long timeOpened) {
+			this.conn = conn;
+			this.timeOpened = timeOpened;
+		}
+	}
 }

bramble-java/src/main/java/org/briarproject/bramble/plugin/DesktopPluginModule.java

@@ -13,6 +13,7 @@ import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
 import org.briarproject.bramble.api.reliability.ReliabilityLayerFactory;
+import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.plugin.bluetooth.JavaBluetoothPluginFactory;
 import org.briarproject.bramble.plugin.modem.ModemPluginFactory;
 import org.briarproject.bramble.plugin.tcp.LanTcpPluginFactory;
@@ -39,10 +40,11 @@ public class DesktopPluginModule extends PluginModule {
 	PluginConfig getPluginConfig(@IoExecutor Executor ioExecutor,
 			SecureRandom random, BackoffFactory backoffFactory,
 			ReliabilityLayerFactory reliabilityFactory,
-			ShutdownManager shutdownManager, EventBus eventBus,
+			ShutdownManager shutdownManager, EventBus eventBus, Clock clock,
 			TimeoutMonitor timeoutMonitor) {
 		DuplexPluginFactory bluetooth = new JavaBluetoothPluginFactory(
-				ioExecutor, random, eventBus, timeoutMonitor, backoffFactory);
+				ioExecutor, random, eventBus, clock, timeoutMonitor,
+				backoffFactory);
 		DuplexPluginFactory modem = new ModemPluginFactory(ioExecutor,
 				reliabilityFactory);
 		DuplexPluginFactory lan = new LanTcpPluginFactory(ioExecutor,

bramble-java/src/main/java/org/briarproject/bramble/plugin/bluetooth/JavaBluetoothPluginFactory.java

@@ -9,6 +9,7 @@ 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.Clock;
 
 import java.security.SecureRandom;
 import java.util.concurrent.Executor;
@@ -30,15 +31,17 @@ public class JavaBluetoothPluginFactory implements DuplexPluginFactory {
 	private final Executor ioExecutor;
 	private final SecureRandom secureRandom;
 	private final EventBus eventBus;
+	private final Clock clock;
 	private final TimeoutMonitor timeoutMonitor;
 	private final BackoffFactory backoffFactory;
 
 	public JavaBluetoothPluginFactory(Executor ioExecutor,
-			SecureRandom secureRandom, EventBus eventBus,
+			SecureRandom secureRandom, EventBus eventBus, Clock clock,
 			TimeoutMonitor timeoutMonitor, BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
 		this.secureRandom = secureRandom;
 		this.eventBus = eventBus;
+		this.clock = clock;
 		this.timeoutMonitor = timeoutMonitor;
 		this.backoffFactory = backoffFactory;
 	}
@@ -56,7 +59,7 @@ public class JavaBluetoothPluginFactory implements DuplexPluginFactory {
 	@Override
 	public DuplexPlugin createPlugin(PluginCallback callback) {
 		BluetoothConnectionLimiter connectionLimiter =
-				new BluetoothConnectionLimiterImpl(eventBus);
+				new BluetoothConnectionLimiterImpl(eventBus, clock);
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		JavaBluetoothPlugin plugin = new JavaBluetoothPlugin(connectionLimiter,