001/**
002 *
003 * Copyright © 2014-2017 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 * <p>
054 * That is the reason Android comes with an API to schedule those tasks: AlarmManager. Which this
055 * class uses to determine every 30 minutes if a server ping is necessary. The interval of 30
056 * minutes is the ideal trade-off between reliability and low resource (battery) consumption.
057 * </p>
058 * <p>
059 * In order to use this class you need to call {@link #onCreate(Context)} <b>once</b>, for example
060 * in the <code>onCreate()</code> method of your Service holding the XMPPConnection. And to avoid
061 * leaking any resources, you should call {@link #onDestroy()} when you no longer need any of its
062 * functionality.
063 * </p>
064 */
065public final class ServerPingWithAlarmManager extends Manager {
066
067    private static final Logger LOGGER = Logger.getLogger(ServerPingWithAlarmManager.class
068            .getName());
069
070    private static final String PING_ALARM_ACTION = "org.igniterealtime.smackx.ping.ACTION";
071
072    private static final Map<XMPPConnection, ServerPingWithAlarmManager> INSTANCES = new WeakHashMap<XMPPConnection, ServerPingWithAlarmManager>();
073
074    static {
075        XMPPConnectionRegistry.addConnectionCreationListener(new ConnectionCreationListener() {
076            @Override
077            public void connectionCreated(XMPPConnection connection) {
078                getInstanceFor(connection);
079            }
080        });
081    }
082
083    public static synchronized ServerPingWithAlarmManager getInstanceFor(XMPPConnection connection) {
084        ServerPingWithAlarmManager serverPingWithAlarmManager = INSTANCES.get(connection);
085        if (serverPingWithAlarmManager == null) {
086            serverPingWithAlarmManager = new ServerPingWithAlarmManager(connection);
087            INSTANCES.put(connection, serverPingWithAlarmManager);
088        }
089        return serverPingWithAlarmManager;
090    }
091
092    private boolean mEnabled = true;
093
094    private ServerPingWithAlarmManager(XMPPConnection connection) {
095        super(connection);
096    }
097
098    /**
099     * If enabled, ServerPingWithAlarmManager will call {@link PingManager#pingServerIfNecessary()}
100     * for the connection of this instance every half hour.
101     *
102     * @param enabled whether or not this manager is should be enabled or not.
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);
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 half hour and
157     * register the alarm broadcast receiver to receive this intent. The receiver will check all
158     * known questions if a ping is Necessary when invoked by the alarm intent.
159     *
160     * @param context an Android context.
161     */
162    public static void onCreate(Context context) {
163        sContext = context;
164        context.registerReceiver(ALARM_BROADCAST_RECEIVER, new IntentFilter(PING_ALARM_ACTION));
165        sAlarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
166        sPendingIntent = PendingIntent.getBroadcast(context, 0, new Intent(PING_ALARM_ACTION), 0);
167        sAlarmManager.setInexactRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP,
168                SystemClock.elapsedRealtime() + AlarmManager.INTERVAL_HALF_HOUR,
169                AlarmManager.INTERVAL_HALF_HOUR, sPendingIntent);
170    }
171
172    /**
173     * Unregister the alarm broadcast receiver and cancel the alarm.
174     */
175    public static void onDestroy() {
176        sContext.unregisterReceiver(ALARM_BROADCAST_RECEIVER);
177        sAlarmManager.cancel(sPendingIntent);
178    }
179}