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/*
* JBoss, Home of Professional Open Source
* Copyright 2015, Red Hat, Inc., and individual contributors as indicated
* by the @authors tag.
*
* Licensed 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.jboss.util.deadlock;
import java.util.HashMap;
import java.util.HashSet;
/**
* Created by IntelliJ IDEA.
* User: wburke
* Date: Aug 21, 2003
* Time: 2:10:46 PM
* To change this template use Options | File Templates.
*/
@SuppressWarnings("unchecked")
public class DeadlockDetector
{
// TODO Maybe this should be an MBean in the future
public static DeadlockDetector singleton = new DeadlockDetector();
// This following is for deadlock detection
protected HashMap waiting = new HashMap();
public void deadlockDetection(Object holder, Resource resource)
throws ApplicationDeadlockException
{
HashSet set = new HashSet();
set.add(holder);
Object checkHolder = resource.getResourceHolder();
synchronized (waiting)
{
addWaiting(holder, resource);
while (checkHolder != null)
{
Resource waitingFor = (Resource)waiting.get(checkHolder);
Object holding = null;
if (waitingFor != null)
{
holding = waitingFor.getResourceHolder();
}
if (holding != null)
{
if (set.contains(holding))
{
// removeWaiting should be cleaned up in acquire
String msg = "Application deadlock detected, resource="+resource
+", holder="+holder+", waitingResource="+waitingFor
+", waitingResourceHolder="+holding;
throw new ApplicationDeadlockException(msg, true);
}
set.add(holding);
}
checkHolder = holding;
}
}
}
/**
* Add a transaction waiting for a lock
* @param holder
* @param resource
*/
public void addWaiting(Object holder, Resource resource)
{
synchronized (waiting)
{
waiting.put(holder, resource);
}
}
/**
* Remove a transaction waiting for a lock
* @param holder
*/
public void removeWaiting(Object holder)
{
synchronized (waiting)
{
waiting.remove(holder);
}
}
}