/**
* $RCSfile$
* $Revision$
* $Date$
*
* Copyright 2003-2007 Jive Software.
*
* All rights reserved. Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jivesoftware.smack;
import org.jivesoftware.smack.packet.Packet;
import java.io.IOException;
import java.io.Writer;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
/**
* Writes packets to a XMPP server. Packets are sent using a dedicated thread. Packet
* interceptors can be registered to dynamically modify packets before they're actually
* sent. Packet listeners can be registered to listen for all outgoing packets.
*
* @see Connection#addPacketInterceptor
* @see Connection#addPacketSendingListener
*
* @author Matt Tucker
*/
class PacketWriter {
private Thread writerThread;
private Thread keepAliveThread;
private Writer writer;
private XMPPConnection connection;
private final BlockingQueue<Packet> queue;
volatile boolean done;
/**
* Timestamp when the last stanza was sent to the server. This information is used
* by the keep alive process to only send heartbeats when the connection has been idle.
*/
private long lastActive = System.currentTimeMillis();
/**
* Creates a new packet writer with the specified connection.
*
* @param connection the connection.
*/
protected PacketWriter(XMPPConnection connection) {
this.queue = new ArrayBlockingQueue<Packet>(500, true);
this.connection = connection;
init();
}
/**
* Initializes the writer in order to be used. It is called at the first connection and also
* is invoked if the connection is disconnected by an error.
*/
protected void init() {
this.writer = connection.writer;
done = false;
writerThread = new Thread() {
public void run() {
writePackets(this);
}
};
writerThread.setName("Smack Packet Writer (" + connection.connectionCounterValue + ")");
writerThread.setDaemon(true);
}
/**
* Sends the specified packet to the server.
*
* @param packet the packet to send.
*/
public void sendPacket(Packet packet) {
if (!done) {
// Invoke interceptors for the new packet that is about to be sent. Interceptors
// may modify the content of the packet.
connection.firePacketInterceptors(packet);
try {
queue.put(packet);
}
catch (InterruptedException ie) {
ie.printStackTrace();
return;
}
synchronized (queue) {
queue.notifyAll();
}
// Process packet writer listeners. Note that we're using the sending
// thread so it's expected that listeners are fast.
connection.firePacketSendingListeners(packet);
}
}
/**
* Starts the packet writer thread and opens a connection to the server. The
* packet writer will continue writing packets until {@link #shutdown} or an
* error occurs.
*/
public void startup() {
writerThread.start();
}
/**
* Starts the keep alive process. A white space (aka heartbeat) is going to be
* sent to the server every 30 seconds (by default) since the last stanza was sent
* to the server.
*/
void startKeepAliveProcess() {
// Schedule a keep-alive task to run if the feature is enabled. will write
// out a space character each time it runs to keep the TCP/IP connection open.
int keepAliveInterval = SmackConfiguration.getKeepAliveInterval();
if (keepAliveInterval > 0) {
KeepAliveTask task = new KeepAliveTask(keepAliveInterval);
keepAliveThread = new Thread(task);
task.setThread(keepAliveThread);
keepAliveThread.setDaemon(true);
keepAliveThread.setName("Smack Keep Alive (" + connection.connectionCounterValue + ")");
keepAliveThread.start();
}
}
void setWriter(Writer writer) {
this.writer = writer;
}
/**
* Shuts down the packet writer. Once this method has been called, no further
* packets will be written to the server.
*/
public void shutdown() {
done = true;
synchronized (queue) {
queue.notifyAll();
}
// Interrupt the keep alive thread if one was created
if (keepAliveThread != null)
keepAliveThread.interrupt();
}
/**
* Cleans up all resources used by the packet writer.
*/
void cleanup() {
connection.interceptors.clear();
connection.sendListeners.clear();
}
/**
* Returns the next available packet from the queue for writing.
*
* @return the next packet for writing.
*/
private Packet nextPacket() {
Packet packet = null;
// Wait until there's a packet or we're done.
while (!done && (packet = queue.poll()) == null) {
try {
synchronized (queue) {
queue.wait();
}
}
catch (InterruptedException ie) {
// Do nothing
}
}
return packet;
}
private void writePackets(Thread thisThread) {
try {
// Open the stream.
openStream();
// Write out packets from the queue.
while (!done && (writerThread == thisThread)) {
Packet packet = nextPacket();
if (packet != null) {
synchronized (writer) {
writer.write(packet.toXML());
if (queue.isEmpty()) {
writer.flush();
// Keep track of the last time a stanza was sent to the server
lastActive = System.currentTimeMillis();
}
}
}
}
// Flush out the rest of the queue. If the queue is extremely large, it's possible
// we won't have time to entirely flush it before the socket is forced closed
// by the shutdown process.
try {
synchronized (writer) {
while (!queue.isEmpty()) {
Packet packet = queue.remove();
writer.write(packet.toXML());
}
writer.flush();
}
}
catch (Exception e) {
e.printStackTrace();
}
// Delete the queue contents (hopefully nothing is left).
queue.clear();
// Close the stream.
try {
writer.write("</stream:stream>");
writer.flush();
}
catch (Exception e) {
// Do nothing
}
finally {
try {
writer.close();
}
catch (Exception e) {
// Do nothing
}
}
}
catch (IOException ioe) {
// The exception can be ignored if the the connection is 'done'
// or if the it was caused because the socket got closed
if (!(done || connection.isSocketClosed())) {
done = true;
// packetReader could be set to null by an concurrent disconnect() call.
// Therefore Prevent NPE exceptions by checking packetReader.
if (connection.packetReader != null) {
connection.notifyConnectionError(ioe);
}
}
}
}
/**
* Sends to the server a new stream element. This operation may be requested several times
* so we need to encapsulate the logic in one place. This message will be sent while doing
* TLS, SASL and resource binding.
*
* @throws IOException If an error occurs while sending the stanza to the server.
*/
void openStream() throws IOException {
StringBuilder stream = new StringBuilder();
stream.append("<stream:stream");
stream.append(" to=\"").append(connection.getServiceName()).append("\"");
stream.append(" xmlns=\"jabber:client\"");
stream.append(" xmlns:stream=\"http://etherx.jabber.org/streams\"");
stream.append(" version=\"1.0\">");
writer.write(stream.toString());
writer.flush();
}
/**
* A TimerTask that keeps connections to the server alive by sending a space
* character on an interval.
*/
private class KeepAliveTask implements Runnable {
private int delay;
private Thread thread;
public KeepAliveTask(int delay) {
this.delay = delay;
}
protected void setThread(Thread thread) {
this.thread = thread;
}
public void run() {
try {
// Sleep a minimum of 15 seconds plus delay before sending first heartbeat. This will give time to
// properly finish TLS negotiation and then start sending heartbeats.
Thread.sleep(15000 + delay);
}
catch (InterruptedException ie) {
// Do nothing
}
while (!done && keepAliveThread == thread) {
synchronized (writer) {
// Send heartbeat if no packet has been sent to the server for a given time
if (System.currentTimeMillis() - lastActive >= delay) {
try {
writer.write(" ");
writer.flush();
}
catch (Exception e) {
// Do nothing
}
}
}
try {
// Sleep until we should write the next keep-alive.
Thread.sleep(delay);
}
catch (InterruptedException ie) {
// Do nothing
}
}
}
}
}