Listeners for subscription changes.

api/net/sf/briar/api/db/DatabaseComponent.java

@@ -48,11 +48,11 @@ public interface DatabaseComponent {
 	/** Waits for any open transactions to finish and closes the database. */
 	void close() throws DbException;
 
-	/** Adds a listener to be notified when new messages are available. */
+	/** Adds a listener to be notified when database events occur. */
-	void addListener(MessageListener m);
+	void addListener(DatabaseListener d);
 
 	/** Removes a listener. */
-	void removeListener(MessageListener m);
+	void removeListener(DatabaseListener d);
 
 	/**
 	 * Adds a new contact to the database with the given transport details and

api/net/sf/briar/api/db/DatabaseListener.java

@@ -0,0 +1,13 @@
+package net.sf.briar.api.db;
+
+/** An interface for receiving notifications when database events occur. */
+public interface DatabaseListener {
+
+	static enum Event {
+		MESSAGES_ADDED,
+		SUBSCRIPTIONS_UPDATED,
+		TRANSPORTS_UPDATED
+	};
+
+	void eventOccurred(Event e);
+}

api/net/sf/briar/api/db/MessageListener.java

@@ -1,10 +0,0 @@
-package net.sf.briar.api.db;
-
-/**
- * An interface for receiving notifications when the database may have new
- * messages available.
- */
-public interface MessageListener {
-
-	void messagesAdded();
-}

components/net/sf/briar/db/DatabaseComponentImpl.java

@@ -10,7 +10,7 @@ import net.sf.briar.api.ContactId;
 import net.sf.briar.api.Rating;
 import net.sf.briar.api.db.DatabaseComponent;
 import net.sf.briar.api.db.DbException;
-import net.sf.briar.api.db.MessageListener;
+import net.sf.briar.api.db.DatabaseListener;
 import net.sf.briar.api.db.Status;
 import net.sf.briar.api.protocol.AuthorId;
 import net.sf.briar.api.protocol.Message;
@@ -29,8 +29,8 @@ DatabaseCleaner.Callback {
 	protected final Database<Txn> db;
 	protected final DatabaseCleaner cleaner;
 
-	private final List<MessageListener> listeners =
+	private final List<DatabaseListener> listeners =
-		new ArrayList<MessageListener>(); // Locking: self
+		new ArrayList<DatabaseListener>(); // Locking: self
 	private final Object spaceLock = new Object();
 	private final Object writeLock = new Object();
 	private long bytesStoredSinceLastCheck = 0L; // Locking: spaceLock
@@ -47,15 +47,15 @@ DatabaseCleaner.Callback {
 		cleaner.startCleaning();
 	}
 
-	public void addListener(MessageListener m) {
+	public void addListener(DatabaseListener d) {
 		synchronized(listeners) {
-			listeners.add(m);
+			listeners.add(d);
 		}
 	}
 
-	public void removeListener(MessageListener m) {
+	public void removeListener(DatabaseListener d) {
 		synchronized(listeners) {
-			listeners.remove(m);
+			listeners.remove(d);
 		}
 	}
 
@@ -80,13 +80,13 @@ DatabaseCleaner.Callback {
 	}
 
 	/** Notifies all MessageListeners that new messages may be available. */
-	protected void callMessageListeners() {
+	protected void callListeners(DatabaseListener.Event e) {
 		synchronized(listeners) {
 			if(!listeners.isEmpty()) {
-				// Shuffle the listeners so we don't always send new messages
+				// Shuffle the listeners so we don't always send new packets
 				// to contacts in the same order
 				Collections.shuffle(listeners);
-				for(MessageListener m : listeners) m.messagesAdded();
+				for(DatabaseListener d : listeners) d.eventOccurred(e);
 			}
 		}
 	}

components/net/sf/briar/db/ReadWriteLockDatabaseComponent.java

@@ -12,6 +12,7 @@ import java.util.logging.Logger;
 
 import net.sf.briar.api.ContactId;
 import net.sf.briar.api.Rating;
+import net.sf.briar.api.db.DatabaseListener;
 import net.sf.briar.api.db.DbException;
 import net.sf.briar.api.db.NoSuchContactException;
 import net.sf.briar.api.protocol.Ack;
@@ -193,7 +194,7 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 			contactLock.readLock().unlock();
 		}
 		// Call the listeners outside the lock
-		if(added) callMessageListeners();
+		if(added) callListeners(DatabaseListener.Event.MESSAGES_ADDED);
 	}
 
 	public void findLostBatches(ContactId c) throws DbException {
@@ -742,7 +743,7 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 			contactLock.readLock().unlock();
 		}
 		// Call the listeners outside the lock
-		if(anyAdded) callMessageListeners();
+		if(anyAdded) callListeners(DatabaseListener.Event.MESSAGES_ADDED);
 	}
 
 	public void receiveOffer(ContactId c, Offer o, RequestWriter r)
@@ -931,11 +932,15 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 
 	public void subscribe(Group g) throws DbException {
 		if(LOG.isLoggable(Level.FINE)) LOG.fine("Subscribing to " + g);
+		boolean added = false;
 		subscriptionLock.writeLock().lock();
 		try {
 			Txn txn = db.startTransaction();
 			try {
-				db.addSubscription(txn, g);
+				if(!db.containsSubscription(txn, g.getId())) {
+					db.addSubscription(txn, g);
+					added = true;
+				}
 				db.commitTransaction(txn);
 			} catch(DbException e) {
 				db.abortTransaction(txn);
@@ -944,10 +949,13 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 		} finally {
 			subscriptionLock.writeLock().unlock();
 		}
+		// Call the listeners outside the lock
+		if(added) callListeners(DatabaseListener.Event.SUBSCRIPTIONS_UPDATED);
 	}
 
 	public void unsubscribe(GroupId g) throws DbException {
 		if(LOG.isLoggable(Level.FINE)) LOG.fine("Unsubscribing from " + g);
+		boolean removed = false;
 		contactLock.readLock().lock();
 		try {
 			messageLock.writeLock().lock();
@@ -958,7 +966,10 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 					try {
 						Txn txn = db.startTransaction();
 						try {
-							db.removeSubscription(txn, g);
+							if(db.containsSubscription(txn, g)) {
+								db.removeSubscription(txn, g);
+								removed = true;
+							}
 							db.commitTransaction(txn);
 						} catch(DbException e) {
 							db.abortTransaction(txn);
@@ -976,5 +987,7 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 		} finally {
 			contactLock.readLock().unlock();
 		}
+		// Call the listeners outside the lock
+		if(removed) callListeners(DatabaseListener.Event.SUBSCRIPTIONS_UPDATED);
 	}
 }

components/net/sf/briar/db/SynchronizedDatabaseComponent.java

@@ -11,6 +11,7 @@ import java.util.logging.Logger;
 
 import net.sf.briar.api.ContactId;
 import net.sf.briar.api.Rating;
+import net.sf.briar.api.db.DatabaseListener;
 import net.sf.briar.api.db.DbException;
 import net.sf.briar.api.db.NoSuchContactException;
 import net.sf.briar.api.protocol.Ack;
@@ -146,7 +147,7 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 			}
 		}
 		// Call the listeners outside the lock
-		if(added) callMessageListeners();
+		if(added) callListeners(DatabaseListener.Event.MESSAGES_ADDED);
 	}
 
 	public void findLostBatches(ContactId c) throws DbException {
@@ -550,7 +551,7 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 			}
 		}
 		// Call the listeners outside the lock
-		if(anyAdded) callMessageListeners();
+		if(anyAdded) callListeners(DatabaseListener.Event.MESSAGES_ADDED);
 	}
 
 	public void receiveOffer(ContactId c, Offer o, RequestWriter r)
@@ -691,27 +692,37 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 
 	public void subscribe(Group g) throws DbException {
 		if(LOG.isLoggable(Level.FINE)) LOG.fine("Subscribing to " + g);
+		boolean added = false;
 		synchronized(subscriptionLock) {
 			Txn txn = db.startTransaction();
 			try {
-				db.addSubscription(txn, g);
+				if(!db.containsSubscription(txn, g.getId())) {
+					db.addSubscription(txn, g);
+					added = true;
+				}
 				db.commitTransaction(txn);
 			} catch(DbException e) {
 				db.abortTransaction(txn);
 				throw e;
 			}
 		}
+		// Call the listeners outside the lock
+		if(added) callListeners(DatabaseListener.Event.SUBSCRIPTIONS_UPDATED);
 	}
 
 	public void unsubscribe(GroupId g) throws DbException {
 		if(LOG.isLoggable(Level.FINE)) LOG.fine("Unsubscribing from " + g);
+		boolean removed = false;
 		synchronized(contactLock) {
 			synchronized(messageLock) {
 				synchronized(messageStatusLock) {
 					synchronized(subscriptionLock) {
 						Txn txn = db.startTransaction();
 						try {
-							db.removeSubscription(txn, g);
+							if(db.containsSubscription(txn, g)) {
+								db.removeSubscription(txn, g);
+								removed = true;
+							}
 							db.commitTransaction(txn);
 						} catch(DbException e) {
 							db.abortTransaction(txn);
@@ -721,5 +732,7 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 				}
 			}
 		}
+		// Call the listeners outside the lock
+		if(removed) callListeners(DatabaseListener.Event.SUBSCRIPTIONS_UPDATED);
 	}
 }

test/net/sf/briar/db/DatabaseComponentTest.java

@@ -12,7 +12,7 @@ import net.sf.briar.api.ContactId;
 import net.sf.briar.api.Rating;
 import net.sf.briar.api.db.DatabaseComponent;
 import net.sf.briar.api.db.DbException;
-import net.sf.briar.api.db.MessageListener;
+import net.sf.briar.api.db.DatabaseListener;
 import net.sf.briar.api.db.NoSuchContactException;
 import net.sf.briar.api.db.Status;
 import net.sf.briar.api.protocol.Ack;
@@ -81,7 +81,7 @@ public abstract class DatabaseComponentTest extends TestCase {
 		final Database<Object> database = context.mock(Database.class);
 		final DatabaseCleaner cleaner = context.mock(DatabaseCleaner.class);
 		final Group group = context.mock(Group.class);
-		final MessageListener listener = context.mock(MessageListener.class);
+		final DatabaseListener listener = context.mock(DatabaseListener.class);
 		context.checking(new Expectations() {{
 			allowing(database).startTransaction();
 			will(returnValue(txn));
@@ -104,12 +104,22 @@ public abstract class DatabaseComponentTest extends TestCase {
 			oneOf(database).getTransports(txn, contactId);
 			will(returnValue(transports));
 			// subscribe(group)
+			oneOf(group).getId();
+			will(returnValue(groupId));
+			oneOf(database).containsSubscription(txn, groupId);
+			will(returnValue(false));
 			oneOf(database).addSubscription(txn, group);
+			oneOf(listener).eventOccurred(
+					DatabaseListener.Event.SUBSCRIPTIONS_UPDATED);
 			// getSubscriptions()
 			oneOf(database).getSubscriptions(txn);
 			will(returnValue(Collections.singletonList(groupId)));
 			// unsubscribe(groupId)
+			oneOf(database).containsSubscription(txn, groupId);
+			will(returnValue(true));
 			oneOf(database).removeSubscription(txn, groupId);
+			oneOf(listener).eventOccurred(
+					DatabaseListener.Event.SUBSCRIPTIONS_UPDATED);
 			// removeContact(contactId)
 			oneOf(database).removeContact(txn, contactId);
 			// close()
@@ -1035,7 +1045,7 @@ public abstract class DatabaseComponentTest extends TestCase {
 		@SuppressWarnings("unchecked")
 		final Database<Object> database = context.mock(Database.class);
 		final DatabaseCleaner cleaner = context.mock(DatabaseCleaner.class);
-		final MessageListener listener = context.mock(MessageListener.class);
+		final DatabaseListener listener = context.mock(DatabaseListener.class);
 		context.checking(new Expectations() {{
 			// addLocallyGeneratedMessage(message)
 			oneOf(database).startTransaction();
@@ -1054,7 +1064,8 @@ public abstract class DatabaseComponentTest extends TestCase {
 			oneOf(database).setSendability(txn, messageId, 0);
 			oneOf(database).commitTransaction(txn);
 			// The message was added, so the listener should be called
-			oneOf(listener).messagesAdded();
+			oneOf(listener).eventOccurred(
+					DatabaseListener.Event.MESSAGES_ADDED);
 		}});
 		DatabaseComponent db = createDatabaseComponent(database, cleaner);
 
@@ -1070,7 +1081,7 @@ public abstract class DatabaseComponentTest extends TestCase {
 		@SuppressWarnings("unchecked")
 		final Database<Object> database = context.mock(Database.class);
 		final DatabaseCleaner cleaner = context.mock(DatabaseCleaner.class);
-		final MessageListener listener = context.mock(MessageListener.class);
+		final DatabaseListener listener = context.mock(DatabaseListener.class);
 		context.checking(new Expectations() {{
 			// addLocallyGeneratedMessage(message)
 			oneOf(database).startTransaction();