Fixed threading issue when receiving unread messages

src/main/java/envoy/client/net/Client.java

@@ -51,16 +51,17 @@ public class Client implements Closeable {
 	 * will block for up to 5 seconds. If the handshake does exceed this time limit,
 	 * an exception is thrown.
 	 *
-	 * @param credentials the login credentials of the user
-	 * @param localDb     the local database used to persist the current
-	 *                    {@link IdGenerator}
-	 * @return a message cache containing all unread messages from the server that
-	 *         can be relayed after initialization
+	 * @param credentials          the login credentials of the user
+	 * @param localDb              the local database used to persist the current
+	 *                             {@link IdGenerator}
+	 * @param receivedMessageCache a message cache containing all unread messages
+	 *                             from the server that can be relayed after
+	 *                             initialization
 	 * @throws Exception if the online mode could not be entered or the request
 	 *                   failed for some other reason
 	 * @since Envoy v0.2-alpha
 	 */
-	public Cache<Message> onlineInit(LoginCredentials credentials, LocalDb localDb) throws Exception {
+	public void onlineInit(LoginCredentials credentials, LocalDb localDb, Cache<Message> receivedMessageCache) throws Exception {
 		// Establish TCP connection
 		logger.info(String.format("Attempting connection to server %s:%d...", config.getServer(), config.getPort()));
 		socket = new Socket(config.getServer(), config.getPort());
@@ -69,13 +70,10 @@ public class Client implements Closeable {
 		// Create message receiver
 		receiver = new Receiver(socket.getInputStream());
 
-		// Create cache for unread messages
-		final Cache<Message> cache = new Cache<>();
-
 		// Register user creation processor, contact list processor and message cache
 		receiver.registerProcessor(User.class, sender -> { logger.info("Acquired user object " + sender); this.sender = sender; });
 		receiver.registerProcessor(Contacts.class, contacts -> { logger.info("Acquired contacts object " + contacts); this.contacts = contacts; });
-		receiver.registerProcessor(Message.class, cache);
+		receiver.registerProcessor(Message.class, receivedMessageCache);
 
 		// Start receiver
 		new Thread(receiver).start();
@@ -104,7 +102,7 @@ public class Client implements Closeable {
 		receiver.registerProcessor(Message.class, receivedMessageProcessor);
 
 		// Relay cached unread messages
-		cache.setProcessor(receivedMessageProcessor);
+		receivedMessageCache.setProcessor(receivedMessageProcessor);
 
 		// Process message status changes
 		receiver.registerProcessor(MessageStatusChangeEvent.class, new MessageStatusChangeEventProcessor());
@@ -117,8 +115,6 @@ public class Client implements Closeable {
 
 		// Request a generator if none is present or the existing one is consumed
 		if (!localDb.hasIdGenerator() || !localDb.getIdGenerator().hasNext()) requestIdGenerator();
-
-		return cache;
 	}
 
 	/**