Added a method for getting unread message counts for all groups.

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

@@ -406,6 +406,13 @@ interface Database<T> {
 	 */
 	long getTransportsSent(T txn, ContactId c) throws DbException;
 
+	/**
+	 * Returns the number of unread messages in each subscribed group.
+	 * <p>
+	 * Locking: message read, messageFlag read, subscription read.
+	 */
+	Map<GroupId, Integer> getUnreadMessageCounts(T txn) throws DbException;
+
 	/**
 	 * Returns the contacts to which the given group is visible.
 	 * <p>

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

@@ -885,6 +885,34 @@ DatabaseCleaner.Callback {
 		}
 	}
 
+	public Map<GroupId, Integer> getUnreadMessageCounts() throws DbException {
+		messageLock.readLock().lock();
+		try {
+			messageFlagLock.readLock().lock();
+			try {
+				subscriptionLock.readLock().lock();
+				try {
+					T txn = db.startTransaction();
+					try {
+						Map<GroupId, Integer> counts =
+							db.getUnreadMessageCounts(txn);
+						db.commitTransaction(txn);
+						return counts;
+					} catch(DbException e) {
+						db.abortTransaction(txn);
+						throw e;
+					}
+				} finally {
+					subscriptionLock.readLock().unlock();
+				}
+			} finally {
+				messageFlagLock.readLock().unlock();
+			}
+		} finally {
+			messageLock.readLock().unlock();
+		}
+	}
+
 	public Collection<ContactId> getVisibility(GroupId g) throws DbException {
 		contactLock.readLock().lock();
 		try {

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

@@ -1709,6 +1709,33 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	public Map<GroupId, Integer> getUnreadMessageCounts(Connection txn)
+	throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT groupId, COUNT(*)"
+				+ " FROM messages LEFT OUTER JOIN flags"
+				+ " ON messages.messageId = flags.messageId"
+				+ " WHERE (NOT read) OR (read IS NULL)"
+				+ " GROUP BY groupId";
+			ps = txn.prepareStatement(sql);
+			rs = ps.executeQuery();
+			Map<GroupId, Integer> counts = new HashMap<GroupId, Integer>();
+			while(rs.next()) {
+				GroupId g = new GroupId(rs.getBytes(1));
+				counts.put(g, rs.getInt(2));
+			}
+			rs.close();
+			ps.close();
+			return counts;
+		} catch(SQLException e) {
+			tryToClose(rs);
+			tryToClose(ps);
+			throw new DbException(e);
+		}
+	}
+
 	public Collection<ContactId> getVisibility(Connection txn, GroupId g)
 	throws DbException {
 		PreparedStatement ps = null;