QPID-2931: update MessageReference to stop nulling out the ServerMessage reference upon release for now, preventing NPE's experienced due to race conditions resulting in use of getMessage() after release.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk/qpid@1032291 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 7 insertions, 6 deletions

diff --git a/java/broker/src/main/java/org/apache/qpid/server/message/MessageReference.java b/java/broker/src/main/java/org/apache/qpid/server/message/MessageReference.java
index 055403ff08..399f8f9327 100644
--- a/java/broker/src/main/java/org/apache/qpid/server/message/MessageReference.java
+++ b/java/broker/src/main/java/org/apache/qpid/server/message/MessageReference.java
@@ -20,13 +20,12 @@
  */
 package org.apache.qpid.server.message;
 
-import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 public abstract class MessageReference<M extends ServerMessage>
 {
 
-    private static final AtomicReferenceFieldUpdater<MessageReference, ServerMessage> _messageUpdater =
-            AtomicReferenceFieldUpdater.newUpdater(MessageReference.class, ServerMessage.class,"_message");
+    private final AtomicBoolean _released = new AtomicBoolean(false);
 
     private volatile M _message;
 
@@ -47,10 +46,12 @@ public abstract class MessageReference<M extends ServerMessage>
 
     public void release()
     {
-        M message = (M) _messageUpdater.getAndSet(this,null);
-        if(message != null)
+        if(!_released.getAndSet(true))
         {
-            onRelease(message);
+            if(_message != null)
+            {
+                onRelease(_message);
+            }
         }
     }