org.apache.bookkeeper.mledger.util.CallbackMutex Maven / Gradle / Ivy
/**
* 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.bookkeeper.mledger.util;
import java.util.concurrent.Semaphore;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Mutex object that can be acquired from a thread and released from a different thread.
*
* This is meant to be acquired when calling an asynchronous method and released in its callback which is probably
* executed in a different thread.
*/
public class CallbackMutex {
private Semaphore semaphore = new Semaphore(1, true);
String owner;
String position;
public void lock() {
semaphore.acquireUninterruptibly();
if (log.isDebugEnabled()) {
owner = Thread.currentThread().getName();
position = Thread.currentThread().getStackTrace()[2].toString();
log.debug("<<< Lock {} acquired at {}", this.hashCode(), position);
}
}
public boolean tryLock() {
if (!semaphore.tryAcquire()) {
return false;
}
if (log.isDebugEnabled()) {
owner = Thread.currentThread().getName();
position = Thread.currentThread().getStackTrace()[2].toString();
log.debug("<<< Lock {} acquired at {}", this.hashCode(), position);
}
return true;
}
public void unlock() {
if (log.isDebugEnabled()) {
owner = null;
position = null;
log.debug(">>> Lock {} released token={} at {}", this.hashCode(),
Thread.currentThread().getStackTrace()[2]);
}
semaphore.release();
}
private static final Logger log = LoggerFactory.getLogger(CallbackMutex.class);
}