/**
* Copyright 2012-2013 Florian Schmaus
*
* 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.keepalive;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import org.jivesoftware.smack.Connection;
import org.jivesoftware.smack.ConnectionCreationListener;
import org.jivesoftware.smack.ConnectionListener;
import org.jivesoftware.smack.PacketCollector;
import org.jivesoftware.smack.PacketListener;
import org.jivesoftware.smack.SmackConfiguration;
import org.jivesoftware.smack.filter.PacketFilter;
import org.jivesoftware.smack.filter.PacketIDFilter;
import org.jivesoftware.smack.packet.Packet;
import org.jivesoftware.smack.ping.PingFailedListener;
import org.jivesoftware.smack.ping.packet.Ping;
/**
* Using an implementation of <a href="http://www.xmpp.org/extensions/xep-0199.html">XMPP Ping (XEP-0199)</a>. This
* class provides keepalive functionality with the server that will periodically "ping" the server to maintain and/or
* verify that the connection still exists.
* <p>
* The ping is done at the application level and is therefore protocol agnostic. It will thus work for both standard TCP
* connections as well as BOSH or any other transport protocol. It will also work regardless of whether the server
* supports the Ping extension, since an error response to the ping serves the same purpose as a pong.
*
* @author Florian Schmaus
*/
public class KeepAliveManager {
private static Map<Connection, KeepAliveManager> instances = new HashMap<Connection, KeepAliveManager>();
private static volatile ScheduledExecutorService periodicPingExecutorService;
static {
if (SmackConfiguration.getKeepAliveInterval() > 0) {
Connection.addConnectionCreationListener(new ConnectionCreationListener() {
public void connectionCreated(Connection connection) {
new KeepAliveManager(connection);
}
});
}
}
private Connection connection;
private long pingInterval = SmackConfiguration.getKeepAliveInterval();
private Set<PingFailedListener> pingFailedListeners = Collections.synchronizedSet(new HashSet<PingFailedListener>());
private volatile ScheduledFuture<?> periodicPingTask;
private volatile long lastSuccessfulContact = -1;
/**
* Retrieves a {@link KeepAliveManager} for the specified {@link Connection}, creating one if it doesn't already
* exist.
*
* @param connection
* The connection the manager is attached to.
* @return The new or existing manager.
*/
public synchronized static KeepAliveManager getInstanceFor(Connection connection) {
KeepAliveManager pingManager = instances.get(connection);
if (pingManager == null) {
pingManager = new KeepAliveManager(connection);
instances.put(connection, pingManager);
}
return pingManager;
}
/*
* Start the executor service if it hasn't been started yet.
*/
private synchronized static void enableExecutorService() {
if (periodicPingExecutorService == null) {
periodicPingExecutorService = new ScheduledThreadPoolExecutor(1, new ThreadFactory() {
@Override
public Thread newThread(Runnable runnable) {
Thread pingThread = new Thread(runnable, "Smack Keepalive");
pingThread.setDaemon(true);
return pingThread;
}
});
}
}
/*
* Stop the executor service if all monitored connections are disconnected.
*/
private synchronized static void handleDisconnect(Connection con) {
if (periodicPingExecutorService != null) {
instances.remove(con);
if (instances.isEmpty()) {
periodicPingExecutorService.shutdownNow();
periodicPingExecutorService = null;
}
}
}
private KeepAliveManager(Connection connection) {
this.connection = connection;
init();
handleConnect();
}
/*
* Call after every connection to add the packet listener.
*/
private void handleConnect() {
// Listen for all incoming packets and reset the scheduled ping whenever
// one arrives.
connection.addPacketListener(new PacketListener() {
@Override
public void processPacket(Packet packet) {
// reschedule the ping based on this last server contact
lastSuccessfulContact = System.currentTimeMillis();
schedulePingServerTask();
}
}, null);
}
private void init() {
connection.addConnectionListener(new ConnectionListener() {
@Override
public void connectionClosed() {
stopPingServerTask();
handleDisconnect(connection);
}
@Override
public void connectionClosedOnError(Exception arg0) {
stopPingServerTask();
handleDisconnect(connection);
}
@Override
public void reconnectionSuccessful() {
handleConnect();
schedulePingServerTask();
}
@Override
public void reconnectingIn(int seconds) {
}
@Override
public void reconnectionFailed(Exception e) {
}
});
instances.put(connection, this);
schedulePingServerTask();
}
/**
* Sets the ping interval.
*
* @param pingInterval
* The new ping time interval in milliseconds.
*/
public void setPingInterval(long newPingInterval) {
if (pingInterval == newPingInterval)
return;
// Enable the executor service
if (newPingInterval > 0)
enableExecutorService();
pingInterval = newPingInterval;
if (pingInterval < 0) {
stopPinging();
}
else {
schedulePingServerTask();
}
}
/**
* Stops pinging the server. This cannot stop a ping that has already started, but will prevent another from being triggered.
* <p>
* To restart, call {@link #setPingInterval(long)}.
*/
public void stopPinging() {
pingInterval = -1;
stopPingServerTask();
}
/**
* Gets the ping interval.
*
* @return The ping interval in milliseconds.
*/
public long getPingInterval() {
return pingInterval;
}
/**
* Add listener for notification when a server ping fails.
*
* <p>
* Please note that this doesn't necessarily mean that the connection is lost, a slow to respond server could also
* cause a failure due to taking too long to respond and thus causing a reply timeout.
*
* @param listener
* The listener to be called
*/
public void addPingFailedListener(PingFailedListener listener) {
pingFailedListeners.add(listener);
}
/**
* Remove the listener.
*
* @param listener
* The listener to be removed.
*/
public void removePingFailedListener(PingFailedListener listener) {
pingFailedListeners.remove(listener);
}
/**
* Returns the elapsed time (in milliseconds) since the last successful contact with the server
* (i.e. the last time any message was received).
* <p>
* <b>Note</b>: Result is -1 if no message has been received since manager was created and
* 0 if the elapsed time is negative due to a clock reset.
*
* @return Elapsed time since last message was received.
*/
public long getTimeSinceLastContact() {
if (lastSuccessfulContact == -1)
return lastSuccessfulContact;
long delta = System.currentTimeMillis() - lastSuccessfulContact;
return (delta < 0) ? 0 : delta;
}
/**
* Cancels any existing periodic ping task if there is one and schedules a new ping task if pingInterval is greater
* then zero.
*
* This is designed so only one executor is used for scheduling all pings on all connections. This results in only 1 thread used for pinging.
*/
private synchronized void schedulePingServerTask() {
enableExecutorService();
stopPingServerTask();
if (pingInterval > 0) {
periodicPingTask = periodicPingExecutorService.schedule(new Runnable() {
@Override
public void run() {
Ping ping = new Ping();
PacketFilter responseFilter = new PacketIDFilter(ping.getPacketID());
final PacketCollector response = pingFailedListeners.isEmpty() ? null : connection.createPacketCollector(responseFilter);
connection.sendPacket(ping);
if (response != null) {
// Schedule a collector for the ping reply, notify listeners if none is received.
periodicPingExecutorService.schedule(new Runnable() {
@Override
public void run() {
Packet result = response.nextResult(1);
// Stop queuing results
response.cancel();
// The actual result of the reply can be ignored since we only care if we actually got one.
if (result == null) {
for (PingFailedListener listener : pingFailedListeners) {
listener.pingFailed();
}
}
}
}, SmackConfiguration.getPacketReplyTimeout(), TimeUnit.MILLISECONDS);
}
}
}, getPingInterval(), TimeUnit.MILLISECONDS);
}
}
private void stopPingServerTask() {
if (periodicPingTask != null) {
periodicPingTask.cancel(true);
periodicPingTask = null;
}
}
}