Fix for ConcurrentModificationException

(cherry picked from commit 925fa70)

Author: vikinghawk

src/main/java/com/rabbitmq/client/impl/recovery/AutorecoveringChannel.java

@@ -18,6 +18,7 @@
 import com.rabbitmq.client.*;
 import com.rabbitmq.client.impl.AMQCommand;
 import com.rabbitmq.client.impl.recovery.Utils.IoTimeoutExceptionRunnable;
+import com.rabbitmq.utility.Utility;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -39,11 +40,11 @@ public class AutorecoveringChannel implements RecoverableChannel {
 
     private volatile RecoveryAwareChannelN delegate;
     private volatile AutorecoveringConnection connection;
-    private final List<ShutdownListener> shutdownHooks  = new CopyOnWriteArrayList<ShutdownListener>();
-    private final List<RecoveryListener> recoveryListeners = new CopyOnWriteArrayList<RecoveryListener>();
-    private final List<ReturnListener> returnListeners = new CopyOnWriteArrayList<ReturnListener>();
-    private final List<ConfirmListener> confirmListeners = new CopyOnWriteArrayList<ConfirmListener>();
-    private final Set<String> consumerTags = Collections.synchronizedSet(new HashSet<String>());
+    private final List<ShutdownListener> shutdownHooks  = new CopyOnWriteArrayList<>();
+    private final List<RecoveryListener> recoveryListeners = new CopyOnWriteArrayList<>();
+    private final List<ReturnListener> returnListeners = new CopyOnWriteArrayList<>();
+    private final List<ConfirmListener> confirmListeners = new CopyOnWriteArrayList<>();
+    private final Set<String> consumerTags = Collections.synchronizedSet(new HashSet<>());
     private int prefetchCountConsumer;
     private int prefetchCountGlobal;
     private boolean usesPublisherConfirms;
@@ -100,7 +101,7 @@ private void executeAndClean(IoTimeoutExceptionRunnable callback) throws IOExcep
         try {
             callback.run();
         } finally {
-            for (String consumerTag : consumerTags) {
+            for (String consumerTag : Utility.copy(consumerTags)) {
                 this.deleteRecordedConsumer(consumerTag);
             }
             this.connection.unregisterChannel(this);

src/main/java/com/rabbitmq/utility/Utility.java

@@ -20,8 +20,10 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 /**
  * Catch-all holder class for static helper methods.
@@ -91,6 +93,21 @@ public static String makeStackTrace(Throwable throwable) {
         return text;
     }
 
+    /**
+     * Synchronizes on the set and then returns a copy of the set that is safe to iterate over. Useful when wanting to do thread-safe iteration over
+     * a Set wrapped in {@link Collections#synchronizedSet(Set)}.
+     *
+     * @param set
+     *            The set, which may not be {@code null}
+     * @return LinkedHashSet copy of the list
+     */
+    public static <E> Set<E> copy(final Set<E> set) {
+        // No Sonar: this very list instance can be synchronized in other places of its owning class
+        synchronized (set) { //NOSONAR
+            return new LinkedHashSet<>(set);
+        }
+    }
+    
     /**
      * Synchronizes on the list and then returns a copy of the list that is safe to iterate over. Useful when wanting to do thread-safe iteration over
      * a List wrapped in {@link Collections#synchronizedList(List)}.
@@ -102,7 +119,7 @@ public static String makeStackTrace(Throwable throwable) {
     public static <E> List<E> copy(final List<E> list) {
         // No Sonar: this very list instance can be synchronized in other places of its owning class
         synchronized (list) { //NOSONAR
-            return new ArrayList<E>(list);
+            return new ArrayList<>(list);
         }
     }
 
@@ -117,7 +134,7 @@ public static <E> List<E> copy(final List<E> list) {
     public static <K, V> Map<K, V> copy(final Map<K, V> map) {
         // No Sonar: this very map instance can be synchronized in other places of its owning class
         synchronized (map) { //NOSONAR
-            return new LinkedHashMap<K, V>(map);
+            return new LinkedHashMap<>(map);
         }
     }
 }