From a420312a404483fd48488832975767d19a4fc5a9 Mon Sep 17 00:00:00 2001
From: James Strachan <jstrachan@apache.org>
Date: Thu, 24 Aug 2006 14:01:30 +0000
Subject: [PATCH] avoid the possibility that 2 threads could attempt to add a
 destination at the same time causing it to be created twice and avoid issues
 such as duplicate registration in JMX

git-svn-id: https://svn.apache.org/repos/asf/incubator/activemq/trunk@434397 13f79535-47bb-0310-9956-ffa450edef68
---
 .../broker/region/AbstractRegion.java         | 42 +++++++++++--------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/activemq-core/src/main/java/org/apache/activemq/broker/region/AbstractRegion.java b/activemq-core/src/main/java/org/apache/activemq/broker/region/AbstractRegion.java
index 7e517fb8c1..c0ae11478e 100755
--- a/activemq-core/src/main/java/org/apache/activemq/broker/region/AbstractRegion.java
+++ b/activemq-core/src/main/java/org/apache/activemq/broker/region/AbstractRegion.java
@@ -77,24 +77,32 @@ abstract public class AbstractRegion implements Region {
     
     public Destination addDestination(ConnectionContext context, ActiveMQDestination destination) throws Exception {
         log.debug("Adding destination: "+destination);
-        Destination dest = createDestination(context, destination);
         
-        // intercept if there is a valid interceptor defined
-        DestinationInterceptor destinationInterceptor = broker.getDestinationInterceptor();
-        if (destinationInterceptor != null) {
-            dest = destinationInterceptor.intercept(dest);
-        }
-        
-        dest.start();
-        synchronized(destinationsMutex){
-            destinations.put(destination,dest);
-            destinationMap.put(destination,dest);
-            
-            // Add all consumers that are interested in the destination. 
-            for (Iterator iter = subscriptions.values().iterator(); iter.hasNext();) {
-                Subscription sub = (Subscription) iter.next();
-                if( sub.matches(destination) ) {
-                    dest.addSubscription(context, sub);
+        synchronized (destinationsMutex) {
+            Destination dest = (Destination) destinations.get(destination);
+            if (dest != null) {
+                log.warn("Attempt to add destination which is already created: " + destination);
+            }
+            else {
+                dest = createDestination(context, destination);
+
+                // intercept if there is a valid interceptor defined
+                DestinationInterceptor destinationInterceptor = broker.getDestinationInterceptor();
+                if (destinationInterceptor != null) {
+                    dest = destinationInterceptor.intercept(dest);
+                }
+
+                dest.start();
+
+                destinations.put(destination, dest);
+                destinationMap.put(destination, dest);
+
+                // Add all consumers that are interested in the destination.
+                for (Iterator iter = subscriptions.values().iterator(); iter.hasNext();) {
+                    Subscription sub = (Subscription) iter.next();
+                    if (sub.matches(destination)) {
+                        dest.addSubscription(context, sub);
+                    }
                 }
             }
             return dest;