Synchronise access to channelNameToChannelMap

src/main/java/com/pusher/client/channel/impl/ChannelManager.java

@@ -1,7 +1,7 @@
 package com.pusher.client.channel.impl;
 
-import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 import com.google.gson.Gson;
 import com.pusher.client.AuthorizationFailureException;
@@ -20,7 +20,8 @@
 public class ChannelManager implements ConnectionEventListener {
 
     private static final Gson GSON = new Gson();
-    private final Map<String, InternalChannel> channelNameToChannelMap = new HashMap<String, InternalChannel>();
+    private final Map<String, InternalChannel> channelNameToChannelMap = new ConcurrentHashMap<String, InternalChannel>();
+
     private final Factory factory;
     private InternalConnection connection;
 
@@ -70,8 +71,7 @@ public void setConnection(final InternalConnection connection) {
         connection.bind(ConnectionState.CONNECTED, this);
     }
 
-    public void subscribeTo(final InternalChannel channel, final ChannelEventListener listener,
-            final String... eventNames) {
+    public void subscribeTo(final InternalChannel channel, final ChannelEventListener listener, final String... eventNames) {
 
         validateArgumentsAndBindEvents(channel, listener, eventNames);
         channelNameToChannelMap.put(channel.getName(), channel);
@@ -88,7 +88,6 @@ public void unsubscribeFrom(final String channelName) {
         if (channel == null) {
             return;
         }
-
         if (connection.getState() == ConnectionState.CONNECTED) {
             sendUnsubscribeMessage(channel);
         }
@@ -116,8 +115,7 @@ public void onMessage(final String event, final String wholeMessage) {
     public void onConnectionStateChange(final ConnectionStateChange change) {
 
         if (change.getCurrentState() == ConnectionState.CONNECTED) {
-
-            for (final InternalChannel channel : channelNameToChannelMap.values()) {
+            for(final InternalChannel channel : channelNameToChannelMap.values()){
                 sendOrQueueSubscribeMessage(channel);
             }
         }
@@ -181,8 +179,7 @@ public void run() {
         }
     }
 
-    private void validateArgumentsAndBindEvents(final InternalChannel channel, final ChannelEventListener listener,
-            final String... eventNames) {
+    private void validateArgumentsAndBindEvents(final InternalChannel channel, final ChannelEventListener listener, final String... eventNames) {
 
         if (channel == null) {
             throw new IllegalArgumentException("Cannot subscribe to a null channel");

src/test/java/com/pusher/client/channel/impl/ChannelManagerTest.java

@@ -24,6 +24,7 @@
 import com.pusher.client.connection.ConnectionStateChange;
 import com.pusher.client.connection.impl.InternalConnection;
 import com.pusher.client.util.Factory;
+import java.util.concurrent.Executors;
 
 @RunWith(MockitoJUnitRunner.class)
 public class ChannelManagerTest {
@@ -325,7 +326,7 @@ public void testGetChannelFromString(){
 
     @Test
     public void testGetNonExistentChannelFromString(){
-       Channel channel = channelManager.getChannel("woot");
+        Channel channel = channelManager.getChannel("woot");
         assertNull(channel);
     }
 
@@ -369,4 +370,25 @@ public void testGetNonExistentPresenceChannel(){
         PresenceChannel channel = channelManager.getPresenceChannel("presence-yolo");
         assertNull(channel);
     }
+
+    @Test
+    public void testConcurrentModificationExceptionDoesNotHappenWhenConnectionIsEstablished() {
+        for(int i = 0; i<1000; i++) {
+            channelManager.subscribeTo(new ChannelImpl("channel" + i, factory), null);
+        }
+
+        Runnable removeChannels = new Runnable() {
+            @Override
+            public void run() {
+                System.out.println("Start unsubscribe");
+                for(int i=900; i<1000; i++){
+                    channelManager.unsubscribeFrom("channel"+i);
+                }
+                System.out.println("end unsubscribe");
+            }
+        };
+        Executors.newSingleThreadExecutor().submit(removeChannels);
+
+        channelManager.onConnectionStateChange(new ConnectionStateChange(ConnectionState.CONNECTING, ConnectionState.CONNECTED));
+    }
 }