001/**
002 *
003 * Copyright © 2014 Florian Schmaus
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.jivesoftware.smackx.ping.android;
019
020import java.util.HashSet;
021import java.util.Map;
022import java.util.Map.Entry;
023import java.util.Set;
024import java.util.WeakHashMap;
025import java.util.logging.Logger;
026
027import org.jivesoftware.smack.ConnectionCreationListener;
028import org.jivesoftware.smack.Manager;
029import org.jivesoftware.smack.XMPPConnection;
030import org.jivesoftware.smack.XMPPConnectionRegistry;
031import org.jivesoftware.smack.util.Async;
032import org.jivesoftware.smackx.ping.PingManager;
033
034import android.app.AlarmManager;
035import android.app.PendingIntent;
036import android.content.BroadcastReceiver;
037import android.content.Context;
038import android.content.Intent;
039import android.content.IntentFilter;
040import android.os.SystemClock;
041
042/**
043 * Send automatic server pings with the help of {@link AlarmManager}.
044 * <p>
045 * Smack's {@link PingManager} uses a <code>ScheduledThreadPoolExecutor</code> to schedule the
046 * automatic server pings, but on Android, those scheduled pings are not reliable. This is because
047 * the Android device may go into deep sleep where the system will not continue to run this causes
048 * <ul>
049 * <li>the system time to not move forward, which means that the time spent in deep sleep is not
050 * counted towards the scheduled delay time</li>
051 * <li>the scheduled Runnable is not run while the system is in deep sleep.</li>
052 * </ul>
053 * That is the reason Android comes with an API to schedule those tasks: AlarmManager. Which this
054 * class uses to determine every 30 minutes if a server ping is necessary. The interval of 30
055 * minutes is the ideal trade-off between reliability and low resource (battery) consumption.
056 * </p>
057 * <p>
058 * In order to use this class you need to call {@link #onCreate(Context)} <b>once</b>, for example
059 * in the <code>onCreate()</code> method of your Service holding the XMPPConnection. And to avoid
060 * leaking any resources, you should call {@link #onDestroy()} when you no longer need any of its
061 * functionality.
062 * </p>
063 */
064public class ServerPingWithAlarmManager extends Manager {
065
066        private static final Logger LOGGER = Logger.getLogger(ServerPingWithAlarmManager.class
067                        .getName());
068
069        private static final String PING_ALARM_ACTION = "org.igniterealtime.smackx.ping.ACTION";
070
071        private static final Map<XMPPConnection, ServerPingWithAlarmManager> INSTANCES = new WeakHashMap<XMPPConnection, ServerPingWithAlarmManager>();
072
073        static {
074                XMPPConnectionRegistry.addConnectionCreationListener(new ConnectionCreationListener() {
075                        @Override
076                        public void connectionCreated(XMPPConnection connection) {
077                                getInstanceFor(connection);
078                        }
079                });
080        }
081
082        public static synchronized ServerPingWithAlarmManager getInstanceFor(XMPPConnection connection) {
083                ServerPingWithAlarmManager serverPingWithAlarmManager = INSTANCES.get(connection);
084                if (serverPingWithAlarmManager == null) {
085                        serverPingWithAlarmManager = new ServerPingWithAlarmManager(connection);
086                        INSTANCES.put(connection, serverPingWithAlarmManager);
087                }
088                return serverPingWithAlarmManager;
089        }
090
091        private boolean mEnabled = true;
092
093        private ServerPingWithAlarmManager(XMPPConnection connection) {
094                super(connection);
095        }
096
097        /**
098         * If enabled, ServerPingWithAlarmManager will call
099         * {@link PingManager#pingServerIfNecessary()} for the connection of this
100         * instance every half hour.
101         * 
102         * @param enabled
103         */
104        public void setEnabled(boolean enabled) {
105                mEnabled = enabled;
106        }
107
108        public boolean isEnabled() {
109                return mEnabled;
110        }
111
112        private static final BroadcastReceiver ALARM_BROADCAST_RECEIVER = new BroadcastReceiver() {
113                @Override
114                public void onReceive(Context context, Intent intent) {
115                        LOGGER.fine("Ping Alarm broadcast received");
116                        Set<Entry<XMPPConnection, ServerPingWithAlarmManager>> managers;
117                        synchronized (ServerPingWithAlarmManager.class) {
118                                // Make a copy to avoid ConcurrentModificationException when
119                                // iterating directly over INSTANCES and the Set is modified
120                                // concurrently by creating a new ServerPingWithAlarmManager.
121                                managers = new HashSet<>(INSTANCES.entrySet());
122                        }
123                        for (Entry<XMPPConnection, ServerPingWithAlarmManager> entry : managers) {
124                                XMPPConnection connection = entry.getKey();
125                                if (entry.getValue().isEnabled()) {
126                                        LOGGER.fine("Calling pingServerIfNecessary for connection "
127                                                        + connection.getConnectionCounter());
128                                        final PingManager pingManager = PingManager.getInstanceFor(connection);
129                                        // Android BroadcastReceivers have a timeout of 60 seconds.
130                                        // The connections reply timeout may be higher, which causes
131                                        // timeouts of the broadcast receiver and a subsequent ANR
132                                        // of the App of the broadcast receiver. We therefore need
133                                        // to call pingServerIfNecessary() in a new thread to avoid
134                                        // this. It could happen that the device gets back to sleep
135                                        // until the Thread runs, but that's a risk we are willing
136                                        // to take into account as it's unlikely.
137                                        Async.go(new Runnable() {
138                                                @Override
139                                                public void run() {
140                                                        pingManager.pingServerIfNecessary();
141                                                }
142                                        }, "PingServerIfNecessary (" + connection.getConnectionCounter() + ')');
143                                } else {
144                                        LOGGER.fine("NOT calling pingServerIfNecessary (disabled) on connection "
145                                                        + connection.getConnectionCounter());
146                                }
147                        }
148                }
149        };
150
151        private static Context sContext;
152        private static PendingIntent sPendingIntent;
153        private static AlarmManager sAlarmManager;
154
155        /**
156         * Register a pending intent with the AlarmManager to be broadcasted every
157         * half hour and register the alarm broadcast receiver to receive this
158         * intent. The receiver will check all known questions if a ping is
159         * Necessary when invoked by the alarm intent.
160         * 
161         * @param context
162         */
163        public static void onCreate(Context context) {
164                sContext = context;
165                context.registerReceiver(ALARM_BROADCAST_RECEIVER, new IntentFilter(PING_ALARM_ACTION));
166                sAlarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
167                sPendingIntent = PendingIntent.getBroadcast(context, 0, new Intent(PING_ALARM_ACTION), 0);
168                sAlarmManager.setInexactRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP,
169                                SystemClock.elapsedRealtime() + AlarmManager.INTERVAL_HALF_HOUR,
170                                AlarmManager.INTERVAL_HALF_HOUR, sPendingIntent);
171        }
172
173        /**
174         * Unregister the alarm broadcast receiver and cancel the alarm. 
175         */
176        public static void onDestroy() {
177                sContext.unregisterReceiver(ALARM_BROADCAST_RECEIVER);
178                sAlarmManager.cancel(sPendingIntent);
179        }
180}