This commit is contained in:
Clebert Suconic 2019-12-04 20:25:41 -05:00
commit 6504f6fa8d
2 changed files with 93 additions and 8 deletions

View File

@ -23,15 +23,22 @@ public abstract class LazyCreateContext extends ReadOnlyContext {
@Override
public Object lookup(String name) throws NamingException {
try {
return super.lookup(name);
} catch (NameNotFoundException e) {
Object answer = createEntry(name);
if (answer == null) {
throw e;
/*
* The lookup and the internalBind should be performed atomically to avoid
* race conditions between multiple threads where the lookup fails for both
* threads initially then the internalBind fails for the second thread.
*/
synchronized (this) {
try {
return super.lookup(name);
} catch (NameNotFoundException e) {
Object answer = createEntry(name);
if (answer == null) {
throw e;
}
internalBind(name, answer);
return answer;
}
internalBind(name, answer);
return answer;
}
}

View File

@ -0,0 +1,78 @@
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.activemq.artemis.jndi;
import javax.naming.Context;
import javax.naming.InitialContext;
import java.util.Hashtable;
import java.util.UUID;
import org.junit.Assert;
import org.junit.Test;
import static org.apache.activemq.artemis.jndi.ActiveMQInitialContextFactory.DYNAMIC_QUEUE_CONTEXT;
public class JndiTest {
@Test
public void testMultiThreadedDynamicQueueLookup() throws Exception {
final int nThreads = 10;
LookerUpper[] lookerUppers = new LookerUpper[nThreads];
for (int j = 0; j < 100; j++) {
Hashtable<String, String> props = new Hashtable<>();
props.put(Context.INITIAL_CONTEXT_FACTORY, "org.apache.activemq.artemis.jndi.ActiveMQInitialContextFactory");
InitialContext context = new InitialContext(props);
String lookup = DYNAMIC_QUEUE_CONTEXT + "/" + UUID.randomUUID().toString();
for (int i = 0; i < nThreads; i++) {
lookerUppers[i] = new LookerUpper(context, lookup);
}
for (int i = 0; i < nThreads; i++) {
lookerUppers[i].start();
}
for (LookerUpper lookerUpper : lookerUppers) {
lookerUpper.join();
Assert.assertFalse(lookerUpper.failed);
}
context.close();
}
}
class LookerUpper extends Thread {
InitialContext context;
String lookup;
boolean failed = false;
LookerUpper(InitialContext context, String lookup) throws Exception {
this.context = context;
this.lookup = lookup;
}
@Override
public void run() {
try {
context.lookup(lookup);
} catch (Throwable e) {
failed = true;
}
}
}
}