Serialise concurrent calls to updateConnectionStatus().

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

@@ -16,6 +16,7 @@ import android.os.PowerManager;
 import net.freehaven.tor.control.EventHandler;
 import net.freehaven.tor.control.TorControlConnection;
 
+import org.briarproject.bramble.PoliteExecutor;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.event.Event;
@@ -63,8 +64,6 @@ import java.util.concurrent.Future;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
-import java.util.concurrent.locks.Lock;
-import java.util.concurrent.locks.ReentrantLock;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
 import java.util.zip.ZipInputStream;
@@ -111,7 +110,7 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private static final Logger LOG =
 			Logger.getLogger(TorPlugin.class.getName());
 
-	private final Executor ioExecutor;
+	private final Executor ioExecutor, connectionStatusExecutor;
 	private final ScheduledExecutorService scheduler;
 	private final Context appContext;
 	private final LocationUtils locationUtils;
@@ -125,7 +124,6 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private final File torDirectory, torFile, geoIpFile, configFile;
 	private final File doneFile, cookieFile;
 	private final PowerManager.WakeLock wakeLock;
-	private final Lock connectionStatusLock;
 	private final AtomicReference<Future<?>> connectivityCheck =
 			new AtomicReference<>();
 	private final AtomicBoolean used = new AtomicBoolean(false);
@@ -167,7 +165,9 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		// This tag will prevent Huawei's powermanager from killing us.
 		wakeLock = pm.newWakeLock(PARTIAL_WAKE_LOCK, "LocationManagerService");
 		wakeLock.setReferenceCounted(false);
-		connectionStatusLock = new ReentrantLock();
+		// Don't execute more than one connection status check at a time
+		connectionStatusExecutor = new PoliteExecutor("TorPlugin",
+				ioExecutor, 1);
 	}
 
 	@Override
@@ -697,54 +697,44 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void updateConnectionStatus() {
-		ioExecutor.execute(() -> {
+		connectionStatusExecutor.execute(() -> {
 			if (!running) return;
-			try {
-				connectionStatusLock.lock();
-				updateConnectionStatusLocked();
-			} finally {
-				connectionStatusLock.unlock();
-			}
-		});
-	}
+			Object o = appContext.getSystemService(CONNECTIVITY_SERVICE);
+			ConnectivityManager cm = (ConnectivityManager) o;
+			NetworkInfo net = cm.getActiveNetworkInfo();
+			boolean online = net != null && net.isConnected();
+			boolean wifi = online && net.getType() == TYPE_WIFI;
+			String country = locationUtils.getCurrentCountry();
+			boolean blocked = TorNetworkMetadata.isTorProbablyBlocked(
+					country);
+			Settings s = callback.getSettings();
+			int network = s.getInt(PREF_TOR_NETWORK, PREF_TOR_NETWORK_ALWAYS);
 
-	// Locking: connectionStatusLock
-	private void updateConnectionStatusLocked() {
-		Object o = appContext.getSystemService(CONNECTIVITY_SERVICE);
-		ConnectivityManager cm = (ConnectivityManager) o;
-		NetworkInfo net = cm.getActiveNetworkInfo();
-		boolean online = net != null && net.isConnected();
-		boolean wifi = online && net.getType() == TYPE_WIFI;
-		String country = locationUtils.getCurrentCountry();
-		boolean blocked = TorNetworkMetadata.isTorProbablyBlocked(
-				country);
-		Settings s = callback.getSettings();
-		int network = s.getInt(PREF_TOR_NETWORK, PREF_TOR_NETWORK_ALWAYS);
-
-		if (LOG.isLoggable(INFO)) {
-			LOG.info("Online: " + online + ", wifi: " + wifi);
-			if ("".equals(country)) LOG.info("Country code unknown");
-			else LOG.info("Country code: " + country);
-		}
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Online: " + online + ", wifi: " + wifi);
+				if ("".equals(country)) LOG.info("Country code unknown");
+				else LOG.info("Country code: " + country);
+			}
 
-		try {
-			if (!online) {
-				LOG.info("Disabling network, device is offline");
-				enableNetwork(false);
-			} else if (blocked) {
-				LOG.info("Disabling network, country is blocked");
-				enableNetwork(false);
-			} else if (network == PREF_TOR_NETWORK_NEVER
-					|| (network == PREF_TOR_NETWORK_WIFI && !wifi)) {
-				LOG.info("Disabling network due to data setting");
-				enableNetwork(false);
-			} else {
-				LOG.info("Enabling network");
-				enableNetwork(true);
+			try {
+				if (!online) {
+					LOG.info("Disabling network, device is offline");
+					enableNetwork(false);
+				} else if (blocked) {
+					LOG.info("Disabling network, country is blocked");
+					enableNetwork(false);
+				} else if (network == PREF_TOR_NETWORK_NEVER
+						|| (network == PREF_TOR_NETWORK_WIFI && !wifi)) {
+					LOG.info("Disabling network due to data setting");
+					enableNetwork(false);
+				} else {
+					LOG.info("Enabling network");
+					enableNetwork(true);
+				}
+			} catch (IOException e) {
+				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 			}
-		} catch (IOException e) {
-			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-		}
+		});
 	}
 
 	private void scheduleConnectionStatusUpdate() {