Added support for registering listeners with the database that are

called when new messages are available, and a new method
hasSendableMessages(ContactId) that listeners can call to see whether
it's worth trying to create a batch.

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

@@ -48,6 +48,12 @@ 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. */
+	void addListener(MessageListener m);
+
+	/** Removes a listener. */
+	void removeListener(MessageListener m);
+
 	/**
 	 * Adds a new contact to the database with the given transport details and
 	 * returns an ID for the contact.
@@ -112,6 +118,9 @@ public interface DatabaseComponent {
 	/** Returns the contacts to which the given group is visible. */
 	Collection<ContactId> getVisibility(GroupId g) throws DbException;
 
+	/** Returns true if any messages are sendable to the given contact. */
+	boolean hasSendableMessages(ContactId c) throws DbException;
+
 	/** Processes an acknowledgement from the given contact. */
 	void receiveAck(ContactId c, Ack a) throws DbException;
 

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

@@ -0,0 +1,10 @@
+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/Database.java

@@ -109,28 +109,28 @@ interface Database<T> {
 	void addSubscription(T txn, Group g) throws DbException;
 
 	/**
-	 * Returns true iff the database contains the given contact.
+	 * Returns true if the database contains the given contact.
 	 * <p>
 	 * Locking: contacts read.
 	 */
 	boolean containsContact(T txn, ContactId c) throws DbException;
 
 	/**
-	 * Returns true iff the database contains the given message.
+	 * Returns true if the database contains the given message.
 	 * <p>
 	 * Locking: messages read.
 	 */
 	boolean containsMessage(T txn, MessageId m) throws DbException;
 
 	/**
-	 * Returns true iff the user is subscribed to the given group.
+	 * Returns true if the user is subscribed to the given group.
 	 * <p>
 	 * Locking: subscriptions read.
 	 */
 	boolean containsSubscription(T txn, GroupId g) throws DbException;
 
 	/**
-	 * Returns true iff the user is subscribed to the given group and the
+	 * Returns true if the user is subscribed to the given group and the
 	 * group is visible to the given contact.
 	 * <p>
 	 * Locking: contacts read, subscriptions read.
@@ -189,7 +189,8 @@ interface Database<T> {
 	 * if the message is not present in the database or is not sendable to the
 	 * given contact.
 	 * <p>
-	 * Locking: contacts read, messages read, messageStatuses read.
+	 * Locking: contacts read, messages read, messageStatuses read,
+	 * subscriptions read.
 	 */
 	byte[] getMessageIfSendable(T txn, ContactId c, MessageId m)
 	throws DbException;
@@ -246,7 +247,8 @@ interface Database<T> {
 	 * Returns the IDs of some messages that are eligible to be sent to the
 	 * given contact, with a total size less than or equal to the given size.
 	 * <p>
-	 * Locking: contacts read, messages read, messageStatuses read.
+	 * Locking: contacts read, messages read, messageStatuses read,
+	 * subscriptions read.
 	 */
 	Collection<MessageId> getSendableMessages(T txn, ContactId c, int size)
 	throws DbException;
@@ -293,6 +295,13 @@ interface Database<T> {
 	Collection<Group> getVisibleSubscriptions(T txn, ContactId c)
 	throws DbException;
 
+	/**
+	 * Returns true if any messages are sendable to the given contact.
+	 * <p>
+	 * Locking: contacts read, messages read, messageStatuses read.
+	 */
+	boolean hasSendableMessages(T txn, ContactId c) throws DbException;
+
 	/**
 	 * Removes an outstanding batch that has been acknowledged. Any messages in
 	 * the batch that are still considered outstanding (Status.SENT) with

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

@@ -25,7 +25,7 @@ interface DatabaseCleaner {
 		void checkFreeSpaceAndClean() throws DbException;
 
 		/**
-		 * Returns true iff the amount of free storage space available to the
+		 * Returns true if the amount of free storage space available to the
 		 * database should be checked.
 		 */
 		boolean shouldCheckFreeSpace();

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

@@ -1,5 +1,8 @@
 package net.sf.briar.db;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -7,6 +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.Status;
 import net.sf.briar.api.protocol.AuthorId;
 import net.sf.briar.api.protocol.Message;
@@ -25,6 +29,8 @@ DatabaseCleaner.Callback {
 	protected final Database<Txn> db;
 	protected final DatabaseCleaner cleaner;
 
+	private final List<MessageListener> listeners =
+		new ArrayList<MessageListener>(); // Locking: self
 	private final Object spaceLock = new Object();
 	private final Object writeLock = new Object();
 	private long bytesStoredSinceLastCheck = 0L; // Locking: spaceLock
@@ -41,6 +47,18 @@ DatabaseCleaner.Callback {
 		cleaner.startCleaning();
 	}
 
+	public void addListener(MessageListener m) {
+		synchronized(listeners) {
+			listeners.add(m);
+		}
+	}
+
+	public void removeListener(MessageListener m) {
+		synchronized(listeners) {
+			listeners.remove(m);
+		}
+	}
+
 	/**
 	 * Removes the oldest messages from the database, with a total size less
 	 * than or equal to the given size.
@@ -61,6 +79,18 @@ DatabaseCleaner.Callback {
 		return sendability;
 	}
 
+	/** Notifies all MessageListeners that new messages may be available. */
+	protected void callMessageListeners() {
+		synchronized(listeners) {
+			if(!listeners.isEmpty()) {
+				// Shuffle the listeners so we don't always send new messages
+				// to contacts in the same order
+				Collections.shuffle(listeners);
+				for(MessageListener m : listeners) m.messagesAdded();
+			}
+		}
+	}
+
 	public void checkFreeSpaceAndClean() throws DbException {
 		long freeSpace = db.getFreeSpace();
 		while(freeSpace < MIN_FREE_SPACE) {
@@ -85,7 +115,7 @@ DatabaseCleaner.Callback {
 	}
 
 	/**
-	 * Returns true iff the database contains the given contact.
+	 * Returns true if the database contains the given contact.
 	 * <p>
 	 * Locking: contacts read.
 	 */
@@ -121,7 +151,7 @@ DatabaseCleaner.Callback {
 			if(bytesStoredSinceLastCheck > MAX_BYTES_BETWEEN_SPACE_CHECKS) {
 				if(LOG.isLoggable(Level.FINE))
 					LOG.fine(bytesStoredSinceLastCheck
-						+ " bytes stored since last check");
+							+ " bytes stored since last check");
 				bytesStoredSinceLastCheck = 0L;
 				timeOfLastCheck = now;
 				return true;
@@ -234,7 +264,7 @@ DatabaseCleaner.Callback {
 		}
 		if(LOG.isLoggable(Level.FINE))
 			LOG.fine(direct + " messages affected directly, "
-				+ indirect + " indirectly");
+					+ indirect + " indirectly");
 	}
 
 	/**

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

@@ -1226,6 +1226,42 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	public boolean hasSendableMessages(Connection txn, ContactId c)
+	throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT messages.messageId FROM messages"
+				+ " JOIN contactSubscriptions"
+				+ " ON messages.groupId = contactSubscriptions.groupId"
+				+ " JOIN visibilities"
+				+ " ON messages.groupId = visibilities.groupId"
+				+ " JOIN statuses ON messages.messageId = statuses.messageId"
+				+ " WHERE contactSubscriptions.contactId = ?"
+				+ " AND visibilities.contactId = ?"
+				+ " AND statuses.contactId = ?"
+				+ " AND status = ? AND sendability > ZERO()"
+				+ " LIMIT ?";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			ps.setInt(2, c.getInt());
+			ps.setInt(3, c.getInt());
+			ps.setShort(4, (short) Status.NEW.ordinal());
+			ps.setInt(5, 1);
+			rs = ps.executeQuery();
+			boolean found = rs.next();
+			assert !rs.next();
+			rs.close();
+			ps.close();
+			return found;
+		} catch(SQLException e) {
+			tryToClose(rs);
+			tryToClose(ps);
+			tryToClose(txn);
+			throw new DbException(e);
+		}
+	}
+
 	public void removeAckedBatch(Connection txn, ContactId c, BatchId b)
 	throws DbException {
 		PreparedStatement ps = null;

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

@@ -151,6 +151,7 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 	}
 
 	public void addLocallyGeneratedMessage(Message m) throws DbException {
+		boolean added = false;
 		waitForPermissionToWrite();
 		contactLock.readLock().lock();
 		try {
@@ -165,7 +166,7 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 							// Don't store the message if the user has
 							// unsubscribed from the group
 							if(db.containsSubscription(txn, m.getGroup())) {
-								boolean added = storeMessage(txn, m, null);
+								added = storeMessage(txn, m, null);
 								if(!added) {
 									if(LOG.isLoggable(Level.FINE))
 										LOG.fine("Duplicate local message");
@@ -191,6 +192,8 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 		} finally {
 			contactLock.readLock().unlock();
 		}
+		// Call the listeners outside the lock
+		if(added) callMessageListeners();
 	}
 
 	public void findLostBatches(ContactId c) throws DbException {
@@ -293,26 +296,32 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 				int bytesSent = 0;
 				messageStatusLock.readLock().lock();
 				try {
-					Txn txn = db.startTransaction();
+					subscriptionLock.readLock().lock();
 					try {
-						int capacity = b.getCapacity();
-						Iterator<MessageId> it =
-							db.getSendableMessages(txn, c, capacity).iterator();
-						sent = new ArrayList<MessageId>();
-						while(it.hasNext()) {
-							MessageId m = it.next();
-							byte[] message = db.getMessage(txn, m);
-							if(!b.writeMessage(message)) break;
-							bytesSent += message.length;
-							sent.add(m);
+						Txn txn = db.startTransaction();
+						try {
+							int capacity = b.getCapacity();
+							Collection<MessageId> sendable =
+								db.getSendableMessages(txn, c, capacity);
+							Iterator<MessageId> it = sendable.iterator();
+							sent = new ArrayList<MessageId>();
+							while(it.hasNext()) {
+								MessageId m = it.next();
+								byte[] raw = db.getMessage(txn, m);
+								if(!b.writeMessage(raw)) break;
+								bytesSent += raw.length;
+								sent.add(m);
+							}
+							db.commitTransaction(txn);
+						} catch(DbException e) {
+							db.abortTransaction(txn);
+							throw e;
+						} catch(IOException e) {
+							db.abortTransaction(txn);
+							throw e;
 						}
-						db.commitTransaction(txn);
-					} catch(DbException e) {
-						db.abortTransaction(txn);
-						throw e;
-					} catch(IOException e) {
-						db.abortTransaction(txn);
-						throw e;
+					} finally {
+						subscriptionLock.readLock().unlock();
 					}
 				} finally {
 					messageStatusLock.readLock().unlock();
@@ -351,24 +360,29 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 				Collection<MessageId> sent;
 				messageStatusLock.readLock().lock();
 				try{
-					Txn txn = db.startTransaction();
+					subscriptionLock.readLock().lock();
 					try {
-						sent = new ArrayList<MessageId>();
-						int bytesSent = 0;
-						for(MessageId m : requested) {
-							byte[] message = db.getMessageIfSendable(txn, c, m);
-							if(message == null) continue;
-							if(!b.writeMessage(message)) break;
-							bytesSent += message.length;
-							sent.add(m);
+						Txn txn = db.startTransaction();
+						try {
+							sent = new ArrayList<MessageId>();
+							int bytesSent = 0;
+							for(MessageId m : requested) {
+								byte[] raw = db.getMessageIfSendable(txn, c, m);
+								if(raw == null) continue;
+								if(!b.writeMessage(raw)) break;
+								bytesSent += raw.length;
+								sent.add(m);
+							}
+							db.commitTransaction(txn);
+						} catch(DbException e) {
+							db.abortTransaction(txn);
+							throw e;
+						} catch(IOException e) {
+							db.abortTransaction(txn);
+							throw e;
 						}
-						db.commitTransaction(txn);
-					} catch(DbException e) {
-						db.abortTransaction(txn);
-						throw e;
-					} catch(IOException e) {
-						db.abortTransaction(txn);
-						throw e;
+					} finally {
+						subscriptionLock.readLock().unlock();
 					}
 				} finally {
 					messageStatusLock.readLock().unlock();
@@ -610,6 +624,39 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 		}
 	}
 
+	public boolean hasSendableMessages(ContactId c) throws DbException {
+		contactLock.readLock().lock();
+		try {
+			if(!containsContact(c)) throw new NoSuchContactException();
+			messageLock.readLock().lock();
+			try {
+				messageStatusLock.readLock().lock();
+				try {
+					subscriptionLock.readLock().lock();
+					try {
+						Txn txn = db.startTransaction();
+						try {
+							boolean has = db.hasSendableMessages(txn, c);
+							db.commitTransaction(txn);
+							return has;
+						} catch(DbException e) {
+							db.abortTransaction(txn);
+							throw e;
+						}
+					} finally {
+						subscriptionLock.readLock().unlock();
+					}
+				} finally {
+					messageStatusLock.readLock().unlock();
+				}
+			} finally {
+				messageLock.readLock().unlock();
+			}
+		} finally {
+			contactLock.readLock().unlock();
+		}
+	}
+
 	public void receiveAck(ContactId c, Ack a) throws DbException {
 		// Mark all messages in acked batches as seen
 		contactLock.readLock().lock();
@@ -644,6 +691,7 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 	}
 
 	public void receiveBatch(ContactId c, Batch b) throws DbException {
+		boolean anyAdded = false;
 		waitForPermissionToWrite();
 		contactLock.readLock().lock();
 		try {
@@ -661,7 +709,10 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 								received++;
 								GroupId g = m.getGroup();
 								if(db.containsVisibleSubscription(txn, g, c)) {
-									if(storeMessage(txn, m, c)) stored++;
+									if(storeMessage(txn, m, c)) {
+										anyAdded = true;
+										stored++;
+									}
 								}
 							}
 							if(LOG.isLoggable(Level.FINE))
@@ -685,6 +736,8 @@ class ReadWriteLockDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 		} finally {
 			contactLock.readLock().unlock();
 		}
+		// Call the listeners outside the lock
+		if(anyAdded) callMessageListeners();
 	}
 
 	public void receiveOffer(ContactId c, Offer o, RequestWriter r)

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

@@ -116,6 +116,7 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 	}
 
 	public void addLocallyGeneratedMessage(Message m) throws DbException {
+		boolean added = false;
 		waitForPermissionToWrite();
 		synchronized(contactLock) {
 			synchronized(messageLock) {
@@ -126,7 +127,7 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 							// Don't store the message if the user has
 							// unsubscribed from the group
 							if(db.containsSubscription(txn, m.getGroup())) {
-								boolean added = storeMessage(txn, m, null);
+								added = storeMessage(txn, m, null);
 								if(!added) {
 									if(LOG.isLoggable(Level.FINE))
 										LOG.fine("Duplicate local message");
@@ -144,6 +145,8 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 				}
 			}
 		}
+		// Call the listeners outside the lock
+		if(added) callMessageListeners();
 	}
 
 	public void findLostBatches(ContactId c) throws DbException {
@@ -217,31 +220,34 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 			if(!containsContact(c)) throw new NoSuchContactException();
 			synchronized(messageLock) {
 				synchronized(messageStatusLock) {
-					Txn txn = db.startTransaction();
-					try {
-						int capacity = b.getCapacity();
-						Iterator<MessageId> it =
-							db.getSendableMessages(txn, c, capacity).iterator();
-						Collection<MessageId> sent = new ArrayList<MessageId>();
-						int bytesSent = 0;
-						while(it.hasNext()) {
-							MessageId m = it.next();
-							byte[] message = db.getMessage(txn, m);
-							if(!b.writeMessage(message)) break;
-							bytesSent += message.length;
-							sent.add(m);
+					synchronized(subscriptionLock) {
+						Txn txn = db.startTransaction();
+						try {
+							int capacity = b.getCapacity();
+							Collection<MessageId> sendable =
+								db.getSendableMessages(txn, c, capacity);
+							Iterator<MessageId> it = sendable.iterator();
+							Collection<MessageId> sent =
+								new ArrayList<MessageId>();
+							int bytesSent = 0;
+							while(it.hasNext()) {
+								MessageId m = it.next();
+								byte[] raw = db.getMessage(txn, m);
+								if(!b.writeMessage(raw)) break;
+								bytesSent += raw.length;
+								sent.add(m);
+							}
+							BatchId id = b.finish();
+							if(!sent.isEmpty())
+								db.addOutstandingBatch(txn, c, id, sent);
+							db.commitTransaction(txn);
+						} catch(DbException e) {
+							db.abortTransaction(txn);
+							throw e;
+						} catch(IOException e) {
+							db.abortTransaction(txn);
+							throw e;
 						}
-						BatchId id = b.finish();
-						// Record the contents of the batch, unless it's empty
-						if(!sent.isEmpty())
-							db.addOutstandingBatch(txn, c, id, sent);
-						db.commitTransaction(txn);
-					} catch(DbException e) {
-						db.abortTransaction(txn);
-						throw e;
-					} catch(IOException e) {
-						db.abortTransaction(txn);
-						throw e;
 					}
 				}
 			}
@@ -254,29 +260,31 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 			if(!containsContact(c)) throw new NoSuchContactException();
 			synchronized(messageLock) {
 				synchronized(messageStatusLock) {
-					Txn txn = db.startTransaction();
-					try {
-						Collection<MessageId> sent = new ArrayList<MessageId>();
-						int bytesSent = 0;
-						for(MessageId m : requested) {
-							byte[] message = db.getMessageIfSendable(txn, c, m);
-							if(message == null) continue;
-							if(!b.writeMessage(message)) break;
-							bytesSent += message.length;
-							sent.add(m);
+					synchronized(subscriptionLock) {
+						Txn txn = db.startTransaction();
+						try {
+							Collection<MessageId> sent =
+								new ArrayList<MessageId>();
+							int bytesSent = 0;
+							for(MessageId m : requested) {
+								byte[] raw = db.getMessageIfSendable(txn, c, m);
+								if(raw == null) continue;
+								if(!b.writeMessage(raw)) break;
+								bytesSent += raw.length;
+								sent.add(m);
+							}
+							BatchId id = b.finish();
+							if(!sent.isEmpty())
+								db.addOutstandingBatch(txn, c, id, sent);
+							db.commitTransaction(txn);
+							return sent;
+						} catch(DbException e) {
+							db.abortTransaction(txn);
+							throw e;
+						} catch(IOException e) {
+							db.abortTransaction(txn);
+							throw e;
 						}
-						BatchId id = b.finish();
-						// Record the contents of the batch, unless it's empty
-						if(!sent.isEmpty())
-							db.addOutstandingBatch(txn, c, id, sent);
-						db.commitTransaction(txn);
-						return sent;
-					} catch(DbException e) {
-						db.abortTransaction(txn);
-						throw e;
-					} catch(IOException e) {
-						db.abortTransaction(txn);
-						throw e;
 					}
 				}
 			}
@@ -450,6 +458,27 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 		}
 	}
 
+	public boolean hasSendableMessages(ContactId c) throws DbException {
+		synchronized(contactLock) {
+			if(!containsContact(c)) throw new NoSuchContactException();
+			synchronized(messageLock) {
+				synchronized(messageStatusLock) {
+					synchronized(subscriptionLock) {
+						Txn txn = db.startTransaction();
+						try {
+							boolean has = db.hasSendableMessages(txn, c);
+							db.commitTransaction(txn);
+							return has;
+						} catch(DbException e) {
+							db.abortTransaction(txn);
+							throw e;
+						}
+					}
+				}
+			}
+		}
+	}
+
 	public void receiveAck(ContactId c, Ack a) throws DbException {
 		// Mark all messages in acked batches as seen
 		synchronized(contactLock) {
@@ -475,6 +504,7 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 	}
 
 	public void receiveBatch(ContactId c, Batch b) throws DbException {
+		boolean anyAdded = false;
 		waitForPermissionToWrite();
 		synchronized(contactLock) {
 			if(!containsContact(c)) throw new NoSuchContactException();
@@ -488,7 +518,10 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 								received++;
 								GroupId g = m.getGroup();
 								if(db.containsVisibleSubscription(txn, g, c)) {
-									if(storeMessage(txn, m, c)) stored++;
+									if(storeMessage(txn, m, c)) {
+										anyAdded = true;
+										stored++;
+									}
 								}
 							}
 							if(LOG.isLoggable(Level.FINE))
@@ -504,6 +537,8 @@ class SynchronizedDatabaseComponent<Txn> extends DatabaseComponentImpl<Txn> {
 				}
 			}
 		}
+		// Call the listeners outside the lock
+		if(anyAdded) callMessageListeners();
 	}
 
 	public void receiveOffer(ContactId c, Offer o, RequestWriter r)

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

@@ -12,6 +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.NoSuchContactException;
 import net.sf.briar.api.db.Status;
 import net.sf.briar.api.protocol.Ack;
@@ -80,6 +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);
 		context.checking(new Expectations() {{
 			allowing(database).startTransaction();
 			will(returnValue(txn));
@@ -117,6 +119,7 @@ public abstract class DatabaseComponentTest extends TestCase {
 		DatabaseComponent db = createDatabaseComponent(database, cleaner);
 
 		db.open(false);
+		db.addListener(listener);
 		assertEquals(Rating.UNRATED, db.getRating(authorId));
 		assertEquals(contactId, db.addContact(transports));
 		assertEquals(Collections.singletonList(contactId), db.getContacts());
@@ -125,6 +128,7 @@ public abstract class DatabaseComponentTest extends TestCase {
 		assertEquals(Collections.singletonList(groupId), db.getSubscriptions());
 		db.unsubscribe(groupId);
 		db.removeContact(contactId);
+		db.removeListener(listener);
 		db.close();
 
 		context.assertIsSatisfied();
@@ -388,7 +392,7 @@ public abstract class DatabaseComponentTest extends TestCase {
 	}
 
 	@Test
-	public void testAddingASendableMessageTriggersBackwardInclusion()
+	public void testAddingSendableMessageTriggersBackwardInclusion()
 	throws DbException {
 		Mockery context = new Mockery();
 		@SuppressWarnings("unchecked")
@@ -446,11 +450,11 @@ public abstract class DatabaseComponentTest extends TestCase {
 		final Transports transportsUpdate = context.mock(Transports.class);
 		context.checking(new Expectations() {{
 			// Check whether the contact is still in the DB - which it's not
-			exactly(11).of(database).startTransaction();
+			exactly(12).of(database).startTransaction();
 			will(returnValue(txn));
-			exactly(11).of(database).containsContact(txn, contactId);
+			exactly(12).of(database).containsContact(txn, contactId);
 			will(returnValue(false));
-			exactly(11).of(database).commitTransaction(txn);
+			exactly(12).of(database).commitTransaction(txn);
 		}});
 		DatabaseComponent db = createDatabaseComponent(database, cleaner);
 
@@ -485,6 +489,11 @@ public abstract class DatabaseComponentTest extends TestCase {
 			assertTrue(false);
 		} catch(NoSuchContactException expected) {}
 
+		try {
+			db.hasSendableMessages(contactId);
+			assertTrue(false);
+		} catch(NoSuchContactException expected) {}
+
 		try {
 			db.receiveAck(contactId, ack);
 			assertTrue(false);
@@ -1019,4 +1028,65 @@ public abstract class DatabaseComponentTest extends TestCase {
 
 		context.assertIsSatisfied();
 	}
+
+	@Test
+	public void testAddingMessageCallsListeners() throws Exception {
+		Mockery context = new Mockery();
+		@SuppressWarnings("unchecked")
+		final Database<Object> database = context.mock(Database.class);
+		final DatabaseCleaner cleaner = context.mock(DatabaseCleaner.class);
+		final MessageListener listener = context.mock(MessageListener.class);
+		context.checking(new Expectations() {{
+			// addLocallyGeneratedMessage(message)
+			oneOf(database).startTransaction();
+			will(returnValue(txn));
+			oneOf(database).containsSubscription(txn, groupId);
+			will(returnValue(true));
+			oneOf(database).addMessage(txn, message);
+			will(returnValue(true));
+			oneOf(database).getContacts(txn);
+			will(returnValue(Collections.singletonList(contactId)));
+			oneOf(database).setStatus(txn, contactId, messageId, Status.NEW);
+			oneOf(database).getRating(txn, authorId);
+			will(returnValue(Rating.UNRATED));
+			oneOf(database).getNumberOfSendableChildren(txn, messageId);
+			will(returnValue(0));
+			oneOf(database).setSendability(txn, messageId, 0);
+			oneOf(database).commitTransaction(txn);
+			// The message was added, so the listener should be called
+			oneOf(listener).messagesAdded();
+		}});
+		DatabaseComponent db = createDatabaseComponent(database, cleaner);
+
+		db.addListener(listener);
+		db.addLocallyGeneratedMessage(message);
+
+		context.assertIsSatisfied();
+	}
+
+	@Test
+	public void testDuplicateMessageDoesNotCallListeners() throws Exception {
+		Mockery context = new Mockery();
+		@SuppressWarnings("unchecked")
+		final Database<Object> database = context.mock(Database.class);
+		final DatabaseCleaner cleaner = context.mock(DatabaseCleaner.class);
+		final MessageListener listener = context.mock(MessageListener.class);
+		context.checking(new Expectations() {{
+			// addLocallyGeneratedMessage(message)
+			oneOf(database).startTransaction();
+			will(returnValue(txn));
+			oneOf(database).containsSubscription(txn, groupId);
+			will(returnValue(true));
+			oneOf(database).addMessage(txn, message);
+			will(returnValue(false));
+			oneOf(database).commitTransaction(txn);
+			// The message was not added, so the listener should not be called
+		}});
+		DatabaseComponent db = createDatabaseComponent(database, cleaner);
+
+		db.addListener(listener);
+		db.addLocallyGeneratedMessage(message);
+
+		context.assertIsSatisfied();
+	}
 }

test/net/sf/briar/db/H2DatabaseTest.java

@@ -210,12 +210,14 @@ public class H2DatabaseTest extends TestCase {
 
 		// The message should not be sendable
 		assertEquals(0, db.getSendability(txn, messageId));
+		assertFalse(db.hasSendableMessages(txn, contactId));
 		Iterator<MessageId> it =
 			db.getSendableMessages(txn, contactId, ONE_MEGABYTE).iterator();
 		assertFalse(it.hasNext());
 
 		// Changing the sendability to > 0 should make the message sendable
 		db.setSendability(txn, messageId, 1);
+		assertTrue(db.hasSendableMessages(txn, contactId));
 		it = db.getSendableMessages(txn, contactId, ONE_MEGABYTE).iterator();
 		assertTrue(it.hasNext());
 		assertEquals(messageId, it.next());
@@ -223,6 +225,7 @@ public class H2DatabaseTest extends TestCase {
 
 		// Changing the sendability to 0 should make the message unsendable
 		db.setSendability(txn, messageId, 0);
+		assertFalse(db.hasSendableMessages(txn, contactId));
 		it = db.getSendableMessages(txn, contactId, ONE_MEGABYTE).iterator();
 		assertFalse(it.hasNext());
 
@@ -244,12 +247,14 @@ public class H2DatabaseTest extends TestCase {
 		db.setSendability(txn, messageId, 1);
 
 		// The message has no status yet, so it should not be sendable
+		assertFalse(db.hasSendableMessages(txn, contactId));
 		Iterator<MessageId> it =
 			db.getSendableMessages(txn, contactId, ONE_MEGABYTE).iterator();
 		assertFalse(it.hasNext());
 
 		// Changing the status to Status.NEW should make the message sendable
 		db.setStatus(txn, contactId, messageId, Status.NEW);
+		assertTrue(db.hasSendableMessages(txn, contactId));
 		it = db.getSendableMessages(txn, contactId, ONE_MEGABYTE).iterator();
 		assertTrue(it.hasNext());
 		assertEquals(messageId, it.next());
@@ -257,6 +262,7 @@ public class H2DatabaseTest extends TestCase {
 
 		// Changing the status to SENT should make the message unsendable
 		db.setStatus(txn, contactId, messageId, Status.SENT);
+		assertFalse(db.hasSendableMessages(txn, contactId));
 		it = db.getSendableMessages(txn, contactId, ONE_MEGABYTE).iterator();
 		assertFalse(it.hasNext());
 
@@ -283,12 +289,14 @@ public class H2DatabaseTest extends TestCase {
 		db.setStatus(txn, contactId, messageId, Status.NEW);
 
 		// The contact is not subscribed, so the message should not be sendable
+		assertFalse(db.hasSendableMessages(txn, contactId));
 		Iterator<MessageId> it =
 			db.getSendableMessages(txn, contactId, ONE_MEGABYTE).iterator();
 		assertFalse(it.hasNext());
 
 		// The contact subscribing should make the message sendable
 		db.setSubscriptions(txn, contactId, Collections.singleton(group), 1);
+		assertTrue(db.hasSendableMessages(txn, contactId));
 		it = db.getSendableMessages(txn, contactId, ONE_MEGABYTE).iterator();
 		assertTrue(it.hasNext());
 		assertEquals(messageId, it.next());
@@ -296,6 +304,7 @@ public class H2DatabaseTest extends TestCase {
 
 		// The contact unsubscribing should make the message unsendable
 		db.setSubscriptions(txn, contactId, Collections.<Group>emptySet(), 2);
+		assertFalse(db.hasSendableMessages(txn, contactId));
 		it = db.getSendableMessages(txn, contactId, ONE_MEGABYTE).iterator();
 		assertFalse(it.hasNext());
 
@@ -317,12 +326,14 @@ public class H2DatabaseTest extends TestCase {
 		db.setSendability(txn, messageId, 1);
 		db.setStatus(txn, contactId, messageId, Status.NEW);
 
-		// The message is too large to send
+		// The message is sendable, but too large to send
+		assertTrue(db.hasSendableMessages(txn, contactId));
 		Iterator<MessageId> it =
 			db.getSendableMessages(txn, contactId, size - 1).iterator();
 		assertFalse(it.hasNext());
 
 		// The message is just the right size to send
+		assertTrue(db.hasSendableMessages(txn, contactId));
 		it = db.getSendableMessages(txn, contactId, size).iterator();
 		assertTrue(it.hasNext());
 		assertEquals(messageId, it.next());
@@ -347,12 +358,14 @@ public class H2DatabaseTest extends TestCase {
 
 		// The subscription is not visible to the contact, so the message
 		// should not be sendable
+		assertFalse(db.hasSendableMessages(txn, contactId));
 		Iterator<MessageId> it =
 			db.getSendableMessages(txn, contactId, ONE_MEGABYTE).iterator();
 		assertFalse(it.hasNext());
 
 		// Making the subscription visible should make the message sendable
 		db.setVisibility(txn, groupId, Collections.singleton(contactId));
+		assertTrue(db.hasSendableMessages(txn, contactId));
 		it = db.getSendableMessages(txn, contactId, ONE_MEGABYTE).iterator();
 		assertTrue(it.hasNext());
 		assertEquals(messageId, it.next());