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      1 /**
      2  * Copyright 2012-2013 Florian Schmaus
      3  *
      4  * All rights reserved. Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *     http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package org.jivesoftware.smackx.ping;
     18 
     19 import java.lang.ref.WeakReference;
     20 import java.util.Set;
     21 
     22 import org.jivesoftware.smack.Connection;
     23 
     24 class ServerPingTask implements Runnable {
     25 
     26     // This has to be a weak reference because IIRC all threads are roots
     27     // for objects and we have a new thread here that should hold a strong
     28     // reference to connection so that it can be GCed.
     29     private WeakReference<Connection> weakConnection;
     30 
     31     private int delta = 1000; // 1 seconds
     32     private int tries = 3; // 3 tries
     33 
     34     protected ServerPingTask(Connection connection) {
     35         this.weakConnection = new WeakReference<Connection>(connection);
     36     }
     37 
     38     public void run() {
     39         Connection connection = weakConnection.get();
     40         if (connection == null) {
     41             // connection has been collected by GC
     42             // which means we can stop the thread by breaking the loop
     43             return;
     44         }
     45         if (connection.isAuthenticated()) {
     46             PingManager pingManager = PingManager.getInstanceFor(connection);
     47             boolean res = false;
     48 
     49             for (int i = 0; i < tries; i++) {
     50                 if (i != 0) {
     51                     try {
     52                         Thread.sleep(delta);
     53                     } catch (InterruptedException e) {
     54                         // We received an interrupt
     55                         // This only happens if we should stop pinging
     56                         return;
     57                     }
     58                 }
     59                 res = pingManager.pingMyServer();
     60                 // stop when we receive a pong back
     61                 if (res) {
     62                     pingManager.lastSuccessfulPingByTask = System.currentTimeMillis();
     63                     break;
     64                 }
     65             }
     66             if (!res) {
     67                 Set<PingFailedListener> pingFailedListeners = pingManager.getPingFailedListeners();
     68                 for (PingFailedListener l : pingFailedListeners) {
     69                     l.pingFailed();
     70                 }
     71             } else {
     72                 // Ping was successful, wind-up the periodic task again
     73                 pingManager.maybeSchedulePingServerTask();
     74             }
     75         }
     76     }
     77 }
     78