/*
* 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.jackrabbit.core.util;
import static org.apache.jackrabbit.data.core.TransactionContext.isSameThreadId;
import org.apache.jackrabbit.data.core.TransactionContext;
import EDU.oswego.cs.dl.util.concurrent.ReentrantLock;
/**
* A reentrant lock for synchronization.
* Unlike a normal reentrant lock, this one allows the lock
* to be re-entered not just by a thread that's already holding the lock but
* by any thread within the same transaction.
*/
public class XAReentrantLock extends ReentrantLock {
/**
* The active lock holder of this {@link ReentrantLock}
*/
private Object activeId;
/**
* {@inheritDoc}
*/
@Override
public void acquire() throws InterruptedException {
if (Thread.interrupted()) {
throw new InterruptedException();
}
Object currentId = TransactionContext.getCurrentThreadId();
synchronized(this) {
if (currentId == activeId || (activeId != null && isSameThreadId(activeId, currentId))) {
++holds_;
} else {
try {
while (activeId != null) {
wait();
}
activeId = currentId;
holds_ = 1;
} catch (InterruptedException ex) {
notify();
throw ex;
}
}
}
}
/**
* {@inheritDoc}
*/
@Override
public synchronized void release() {
Object currentId = TransactionContext.getCurrentThreadId();
if (activeId != null && !isSameThreadId(activeId, currentId)) {
throw new Error("Illegal Lock usage");
}
if (--holds_ == 0) {
activeId = null;
notify();
}
}
}