/**
* $RCSfile$
* $Revision: 4539 $
* $Date: 2006-07-18 10:47:38 +0400 (Tue, 18 Jul 2006) $
*
* Copyright 2003-2004 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.filter.PacketFilter;
import org.jivesoftware.smack.packet.Packet;
import java.io.IOException;
import java.io.Writer;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
/**
* 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.
*
* @author Matt Tucker
*/
class PacketWriter {
private Thread writerThread;
private Writer writer;
private XMPPConnection connection;
final private LinkedList<Packet> queue;
private boolean done = false;
final private List<ListenerWrapper> listeners = new ArrayList<ListenerWrapper>();
private boolean listenersDeleted = false;
/**
* 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();
/**
* List of PacketInterceptor that will be notified when a new packet is about to be
* sent to the server. These interceptors may modify the packet before it is being
* actually sent to the server.
*/
final private List interceptors = new ArrayList();
/**
* Flag that indicates if an interceptor was deleted. This is an optimization flag.
*/
private boolean interceptorDeleted = false;
/**
* Creates a new packet writer with the specified connection.
*
* @param connection the connection.
*/
protected PacketWriter(XMPPConnection connection) {
this.connection = connection;
this.writer = connection.writer;
this.queue = new LinkedList<Packet>();
writerThread = new Thread() {
public void run() {
writePackets();
}
};
writerThread.setName("Smack Packet Writer");
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.
processInterceptors(packet);
synchronized(queue) {
queue.addFirst(packet);
queue.notifyAll();
}
// Process packet writer listeners. Note that we're using the sending
// thread so it's expected that listeners are fast.
processListeners(packet);
}
}
/**
* Registers a packet listener with this writer. The listener will be
* notified immediately after every packet this writer sends. A packet filter
* determines which packets will be delivered to the listener. Note that the thread
* that writes packets will be used to invoke the listeners. Therefore, each
* packet listener should complete all operations quickly or use a different
* thread for processing.
*
* @param packetListener the packet listener to notify of sent packets.
* @param packetFilter the packet filter to use.
*/
public void addPacketListener(PacketListener packetListener, PacketFilter packetFilter) {
synchronized (listeners) {
listeners.add(new ListenerWrapper(packetListener, packetFilter));
}
}
/**
* Removes a packet listener.
*
* @param packetListener the packet listener to remove.
*/
public void removePacketListener(PacketListener packetListener) {
synchronized (listeners) {
for (int i=0; i<listeners.size(); i++) {
ListenerWrapper wrapper = listeners.get(i);
if (wrapper != null && wrapper.packetListener.equals(packetListener)) {
listeners.set(i, null);
// Set the flag to indicate that the listener list needs
// to be cleaned up.
listenersDeleted = true;
}
}
}
}
/**
* Returns the number of registered packet listeners.
*
* @return the count of packet listeners.
*/
public int getPacketListenerCount() {
synchronized (listeners) {
return listeners.size();
}
}
/**
* Registers a packet interceptor with this writer. The interceptor will be
* notified of every packet that this writer is about to send. Interceptors
* may modify the packet to be sent. A packet filter determines which packets
* will be delivered to the interceptor.
*
* @param packetInterceptor the packet interceptor to notify of packets about to be sent.
* @param packetFilter the packet filter to use.
*/
public void addPacketInterceptor(PacketInterceptor packetInterceptor, PacketFilter packetFilter) {
synchronized (interceptors) {
interceptors.add(new InterceptorWrapper(packetInterceptor, packetFilter));
}
}
/**
* Removes a packet interceptor.
*
* @param packetInterceptor the packet interceptor to remove.
*/
public void removePacketInterceptor(PacketInterceptor packetInterceptor) {
synchronized (interceptors) {
for (int i=0; i<interceptors.size(); i++) {
InterceptorWrapper wrapper = (InterceptorWrapper)interceptors.get(i);
if (wrapper != null && wrapper.packetInterceptor.equals(packetInterceptor)) {
interceptors.set(i, null);
// Set the flag to indicate that the interceptor list needs
// to be cleaned up.
interceptorDeleted = true;
}
}
}
}
/**
* 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) {
Thread keepAliveThread = new Thread(new KeepAliveTask(keepAliveInterval));
keepAliveThread.setDaemon(true);
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;
}
/**
* Returns the next available packet from the queue for writing.
*
* @return the next packet for writing.
*/
private Packet nextPacket() {
synchronized(queue) {
while (!done && queue.size() == 0) {
try {
queue.wait(2000);
}
catch (InterruptedException ie) {
// Do nothing
}
}
if (queue.size() > 0) {
return queue.removeLast();
}
else {
return null;
}
}
}
private void writePackets() {
try {
// Open the stream.
openStream();
// Write out packets from the queue.
while (!done) {
Packet packet = nextPacket();
if (packet != null) {
synchronized (writer) {
writer.write(packet.toXML());
writer.flush();
// Keep track of the last time a stanza was sent to the server
lastActive = System.currentTimeMillis();
}
}
}
// 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){
if (!done) {
done = true;
connection.packetReader.notifyConnectionError(ioe);
}
}
}
/**
* Process listeners.
*/
private void processListeners(Packet packet) {
// Clean up null entries in the listeners list if the flag is set. List
// removes are done seperately so that the main notification process doesn't
// need to synchronize on the list.
synchronized (listeners) {
if (listenersDeleted) {
for (int i=listeners.size()-1; i>=0; i--) {
if (listeners.get(i) == null) {
listeners.remove(i);
}
}
listenersDeleted = false;
}
}
// Notify the listeners of the new sent packet
int size = listeners.size();
for (int i=0; i<size; i++) {
ListenerWrapper listenerWrapper = listeners.get(i);
if (listenerWrapper != null) {
listenerWrapper.notifyListener(packet);
}
}
}
/**
* Process interceptors. Interceptors may modify the packet that is about to be sent.
* Since the thread that requested to send the packet will invoke all interceptors, it
* is important that interceptors perform their work as soon as possible so that the
* thread does not remain blocked for a long period.
*
* @param packet the packet that is going to be sent to the server
*/
private void processInterceptors(Packet packet) {
if (packet != null) {
// Clean up null entries in the interceptors list if the flag is set. List
// removes are done seperately so that the main notification process doesn't
// need to synchronize on the list.
synchronized (interceptors) {
if (interceptorDeleted) {
for (int i=interceptors.size()-1; i>=0; i--) {
if (interceptors.get(i) == null) {
interceptors.remove(i);
}
}
interceptorDeleted = false;
}
}
// Notify the interceptors of the new packet to be sent
int size = interceptors.size();
for (int i=0; i<size; i++) {
InterceptorWrapper interceptorWrapper = (InterceptorWrapper)interceptors.get(i);
if (interceptorWrapper != null) {
interceptorWrapper.notifyListener(packet);
}
}
}
}
/**
* 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.serviceName).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 wrapper class to associate a packet filter with a listener.
*/
private static class ListenerWrapper {
private PacketListener packetListener;
private PacketFilter packetFilter;
public ListenerWrapper(PacketListener packetListener,
PacketFilter packetFilter)
{
this.packetListener = packetListener;
this.packetFilter = packetFilter;
}
public boolean equals(Object object) {
if (object == null) {
return false;
}
if (object instanceof ListenerWrapper) {
return ((ListenerWrapper)object).packetListener.equals(this.packetListener);
}
else if (object instanceof PacketListener) {
return object.equals(this.packetListener);
}
return false;
}
public void notifyListener(Packet packet) {
if (packetFilter == null || packetFilter.accept(packet)) {
packetListener.processPacket(packet);
}
}
}
/**
* A wrapper class to associate a packet filter with an interceptor.
*/
private static class InterceptorWrapper {
private PacketInterceptor packetInterceptor;
private PacketFilter packetFilter;
public InterceptorWrapper(PacketInterceptor packetInterceptor, PacketFilter packetFilter)
{
this.packetInterceptor = packetInterceptor;
this.packetFilter = packetFilter;
}
public boolean equals(Object object) {
if (object == null) {
return false;
}
if (object instanceof InterceptorWrapper) {
return ((InterceptorWrapper) object).packetInterceptor
.equals(this.packetInterceptor);
}
else if (object instanceof PacketInterceptor) {
return object.equals(this.packetInterceptor);
}
return false;
}
public void notifyListener(Packet packet) {
if (packetFilter == null || packetFilter.accept(packet)) {
packetInterceptor.interceptPacket(packet);
}
}
}
/**
* 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;
public KeepAliveTask(int delay) {
this.delay = delay;
}
public void run() {
try {
// Sleep 15 seconds before sending first heartbeat. This will give time to
// properly finish TLS negotiation and then start sending heartbeats.
Thread.sleep(15000);
}
catch (InterruptedException ie) {
// Do nothing
}
while (!done) {
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
}
}
}
}
}