org.springframework.integration.cluster.redis.DistributedLockHandler.java Source code

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Here is the source code for org.springframework.integration.cluster.redis.DistributedLockHandler.java

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/*
 * Copyright 2002-2011 the original author or authors.
 *
 * 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.springframework.integration.cluster.redis;

import java.util.Date;
import java.util.concurrent.TimeUnit;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.dao.CannotAcquireLockException;
import org.springframework.dao.DataRetrievalFailureException;
import org.springframework.data.redis.core.StringRedisTemplate;

/**
 * @author Gary Russell
 *
 */
public class DistributedLockHandler {

    private final Log logger = LogFactory.getLog(this.getClass());

    private ThreadLocal<Date> acquiredThreadLocal = new ThreadLocal<Date>();

    private StringRedisTemplate lockTemplate;

    private int timeout;

    private boolean threadBound = true;

    /**
     * @param lockTemplate
     */
    public DistributedLockHandler(StringRedisTemplate lockTemplate, int timeout) {
        this.lockTemplate = lockTemplate;
        this.timeout = timeout;
    }

    public void acquireLock(String key, String owner) {
        int n = 0;
        while (this.lockTemplate.opsForValue().setIfAbsent(key + ".lock", getLockValue(owner)) == false) {
            if (++n > this.timeout / 100) {
                throw new CannotAcquireLockException("Failed to procure cluster lock for application " + key);
            }
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                throw new DataRetrievalFailureException("Interrupted while procuring lock", e);
            }
        }
        this.acquiredThreadLocal.set(new Date());
        if (logger.isDebugEnabled()) {
            logger.debug("Lock acquiredThreadLocal for " + key + " by " + owner);
        }
        this.lockTemplate.opsForValue().getOperations().expire(key + ".lock", timeout * 2, TimeUnit.MILLISECONDS);
    }

    /**
     * @param owner
     * @return
     */
    private String getLockValue(String owner) {
        if (threadBound) {
            return owner + ":" + Thread.currentThread().getId();
        } else {
            return owner;
        }
    }

    public void relinquishLock(String key, String owner) {
        String instanceInfo = this.lockTemplate.opsForValue().get(key + ".lock");
        if (!getLockValue(owner).equals(instanceInfo)) {
            logger.debug(owner + " cannot relinquish lock; owned by " + instanceInfo);
            return;
        }
        if (threadBound && System.currentTimeMillis() > this.acquiredThreadLocal.get().getTime() + this.timeout) {
            logger.error("Held lock for " + key + " too long - unsafe to relinquish - allowing expiration");
            return;
        }
        this.lockTemplate.opsForValue().getOperations().delete(key + ".lock");
        if (logger.isDebugEnabled()) {
            logger.debug("Lock relinquished for " + key);
        }
    }

    public boolean checkIOwnLock(String key) {
        if (System.currentTimeMillis() > this.acquiredThreadLocal.get().getTime() + this.timeout) {
            String message = "Held lock for " + key + " too long - unsafe to update protected key";
            logger.error(message);
            return false;
        }
        return true;
    }

    public boolean isLocked(String key) {
        boolean isLocked = this.lockTemplate.opsForValue().get(key + ".lock") != null;
        if (logger.isDebugEnabled()) {
            logger.debug(key + ".lock: locked=" + isLocked);
        }
        return isLocked;
    }

    /**
     * @return the threadBound
     */
    public boolean isThreadBound() {
        return threadBound;
    }

    /**
     * @param threadBound the threadBound to set
     */
    public void setThreadBound(boolean threadBound) {
        this.threadBound = threadBound;
    }
}