com.alibaba.rocketmq.client.impl.consumer.MessageQueueLock Maven / Gradle / Ivy
/**
* Copyright (C) 2010-2013 Alibaba Group Holding Limited
*
* 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 com.alibaba.rocketmq.client.impl.consumer;
import java.util.concurrent.ConcurrentHashMap;
import com.alibaba.rocketmq.common.message.MessageQueue;
/**
* Message lock,strictly ensure the single queue only one thread at a time consuming
*
* @author shijia.wxr
* @since 2013-6-25
*/
public class MessageQueueLock {
private ConcurrentHashMap mqLockTable =
new ConcurrentHashMap();
public Object fetchLockObject(final MessageQueue mq) {
Object objLock = this.mqLockTable.get(mq);
if (null == objLock) {
objLock = new Object();
Object prevLock = this.mqLockTable.putIfAbsent(mq, objLock);
if (prevLock != null) {
objLock = prevLock;
}
}
return objLock;
}
}