001/**
002 *
003 * Copyright © 2014-2021 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.Set;
023import java.util.WeakHashMap;
024import java.util.logging.Logger;
025
026import org.jivesoftware.smack.ConnectionCreationListener;
027import org.jivesoftware.smack.Manager;
028import org.jivesoftware.smack.XMPPConnection;
029import org.jivesoftware.smack.XMPPConnectionRegistry;
030import org.jivesoftware.smack.util.Async;
031import org.jivesoftware.smackx.ping.PingManager;
032
033import android.app.AlarmManager;
034import android.app.PendingIntent;
035import android.content.BroadcastReceiver;
036import android.content.Context;
037import android.content.Intent;
038import android.content.IntentFilter;
039import android.os.SystemClock;
040
041/**
042 * Send automatic server pings with the help of {@link AlarmManager}.
043 * <p>
044 * Smack's {@link PingManager} uses a <code>ScheduledThreadPoolExecutor</code> to schedule the
045 * automatic server pings, but on Android, those scheduled pings are not reliable. This is because
046 * the Android device may go into deep sleep where the system will not continue to run this causes
047 * <ul>
048 * <li>the system time to not move forward, which means that the time spent in deep sleep is not
049 * counted towards the scheduled delay time</li>
050 * <li>the scheduled Runnable is not run while the system is in deep sleep.</li>
051 * </ul>
052 * <p>
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 final 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    /**
083     * Get the instance of this manager for the given connection.
084     *
085     * @param connection the connection.
086     * @return the instance of this manager for the given connection.
087     */
088    public static synchronized ServerPingWithAlarmManager getInstanceFor(XMPPConnection connection) {
089        ServerPingWithAlarmManager serverPingWithAlarmManager = INSTANCES.get(connection);
090        if (serverPingWithAlarmManager == null) {
091            serverPingWithAlarmManager = new ServerPingWithAlarmManager(connection);
092            INSTANCES.put(connection, serverPingWithAlarmManager);
093        }
094        return serverPingWithAlarmManager;
095    }
096
097    private boolean mEnabled = true;
098
099    private ServerPingWithAlarmManager(XMPPConnection connection) {
100        super(connection);
101    }
102
103    /**
104     * If enabled, ServerPingWithAlarmManager will call {@link PingManager#pingServerIfNecessary()}
105     * for the connection of this instance every half hour.
106     *
107     * @param enabled whether or not this manager is should be enabled or not.
108     */
109    public void setEnabled(boolean enabled) {
110        mEnabled = enabled;
111    }
112
113    /**
114     * Check if this manager is enabled.
115     *
116     * @return <code>true</code> if this manager is enabled, <code>false</code> otherwise.
117     */
118    public boolean isEnabled() {
119        return mEnabled;
120    }
121
122    private static final BroadcastReceiver ALARM_BROADCAST_RECEIVER = new BroadcastReceiver() {
123        @Override
124        public void onReceive(Context context, Intent intent) {
125            LOGGER.fine("Ping Alarm broadcast received");
126            Set<Map.Entry<XMPPConnection, ServerPingWithAlarmManager>> managers;
127            synchronized (ServerPingWithAlarmManager.class) {
128                // Make a copy to avoid ConcurrentModificationException when
129                // iterating directly over INSTANCES and the Set is modified
130                // concurrently by creating a new ServerPingWithAlarmManager.
131                managers = new HashSet<>(INSTANCES.entrySet());
132            }
133            for (Map.Entry<XMPPConnection, ServerPingWithAlarmManager> entry : managers) {
134                XMPPConnection connection = entry.getKey();
135                if (entry.getValue().isEnabled()) {
136                    LOGGER.fine("Calling pingServerIfNecessary for connection "
137                            + connection);
138                    final PingManager pingManager = PingManager.getInstanceFor(connection);
139                    // Android BroadcastReceivers have a timeout of 60 seconds.
140                    // The connections reply timeout may be higher, which causes
141                    // timeouts of the broadcast receiver and a subsequent ANR
142                    // of the App of the broadcast receiver. We therefore need
143                    // to call pingServerIfNecessary() in a new thread to avoid
144                    // this. It could happen that the device gets back to sleep
145                    // until the Thread runs, but that's a risk we are willing
146                    // to take into account as it's unlikely.
147                    Async.go(new Runnable() {
148                        @Override
149                        public void run() {
150                            pingManager.pingServerIfNecessary();
151                        }
152                    }, "PingServerIfNecessary (" + connection.getConnectionCounter() + ')');
153                } else {
154                    LOGGER.fine("NOT calling pingServerIfNecessary (disabled) on connection "
155                            + connection.getConnectionCounter());
156                }
157            }
158        }
159    };
160
161    private static Context sContext;
162    private static PendingIntent sPendingIntent;
163    private static AlarmManager sAlarmManager;
164
165    /**
166     * Register a pending intent with the AlarmManager to be broadcasted every half hour and
167     * register the alarm broadcast receiver to receive this intent. The receiver will check all
168     * known questions if a ping is Necessary when invoked by the alarm intent.
169     *
170     * @param context an Android context.
171     */
172    public static void onCreate(Context context) {
173        sContext = context;
174        context.registerReceiver(ALARM_BROADCAST_RECEIVER, new IntentFilter(PING_ALARM_ACTION));
175        sAlarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
176        sPendingIntent = PendingIntent.getBroadcast(context, 0, new Intent(PING_ALARM_ACTION), 0);
177        sAlarmManager.setInexactRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP,
178                SystemClock.elapsedRealtime() + AlarmManager.INTERVAL_HALF_HOUR,
179                AlarmManager.INTERVAL_HALF_HOUR, sPendingIntent);
180    }
181
182    /**
183     * Unregister the alarm broadcast receiver and cancel the alarm.
184     */
185    public static void onDestroy() {
186        sContext.unregisterReceiver(ALARM_BROADCAST_RECEIVER);
187        sAlarmManager.cancel(sPendingIntent);
188    }
189}