From 6cfdf2bc6ff9c3a7c0cf0ff6c7bb9507c77f95fc Mon Sep 17 00:00:00 2001
From: Florian Schmaus <flo@geekplace.eu>
Date: Wed, 15 Feb 2017 20:14:41 +0100
Subject: [PATCH] Use CopyOnWriteArraySet for pingFailedListeners

To prevent

java.util.ConcurrentModificationException
  at java.util.HashMap$HashIterator.nextEntry(HashMap.java:788)
  at java.util.HashMap$KeyIterator.next(HashMap.java:815)
  at org.jivesoftware.smackx.ping.PingManager.pingMyServer(PingManager.java:252)
  at org.kontalk.service.msgcenter.MessageCenterService$3.run(MessageCenterService.java:1114)
  at java.lang.Thread.run(Thread.java:818)

Thanks to Daniele Ricci for reporting this.
---
 .../java/org/jivesoftware/smackx/ping/PingManager.java    | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/smack-extensions/src/main/java/org/jivesoftware/smackx/ping/PingManager.java b/smack-extensions/src/main/java/org/jivesoftware/smackx/ping/PingManager.java
index 11f9dcd0f..39b77e81d 100644
--- a/smack-extensions/src/main/java/org/jivesoftware/smackx/ping/PingManager.java
+++ b/smack-extensions/src/main/java/org/jivesoftware/smackx/ping/PingManager.java
@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2012-2015 Florian Schmaus
+ * Copyright 2012-2017 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,11 +16,10 @@
  */
 package org.jivesoftware.smackx.ping;
 
-import java.util.Collections;
-import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.WeakHashMap;
+import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
@@ -105,8 +104,7 @@ public final class PingManager extends Manager {
         defaultPingInterval = interval;
     }
 
-    private final Set<PingFailedListener> pingFailedListeners = Collections
-                    .synchronizedSet(new HashSet<PingFailedListener>());
+    private final Set<PingFailedListener> pingFailedListeners = new CopyOnWriteArraySet<>();
 
     private final ScheduledExecutorService executorService;