package com.java110.utils.lock;
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import com.java110.utils.cache.BaseCache;
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import redis.clients.jedis.Jedis;
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import java.util.Collections;
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import java.util.UUID;
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/**
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* 分布式事务锁
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* add by wuxw 2020-01-11
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*/
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public class DistributedLock extends BaseCache {
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private static final String LOCK_SUCCESS = "OK";
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private static final String SET_IF_NOT_EXIST = "NX";
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private static final String SET_WITH_EXPIRE_TIME = "PX";
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private static final int DEFAULT_EXPIRE_TIME = 1000;
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private static final Long RELEASE_SUCCESS = 1L;
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/**
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* 获取UUID
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*
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* @return
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*/
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public static String getLockUUID() {
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return UUID.randomUUID().toString();
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}
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/**
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* 等待获取锁
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*
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* @param lockKey 锁
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* @param requestId 请求标识
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* @return
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*/
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public static boolean waitGetDistributedLock(String lockKey, String requestId) {
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return waitGetDistributedLock(lockKey, requestId, DEFAULT_EXPIRE_TIME);
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}
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public static boolean waitGetDistributedLock(String lockKey, String requestId, int expireTime) {
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Jedis redis = null;
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try {
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redis = getJedis();
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while (true) {
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if (tryGetDistributedLock(redis, lockKey, requestId, expireTime)) {
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return true;
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}
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}
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} finally {
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if (redis != null) {
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redis.close();
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}
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}
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}
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/**
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* 尝试获取分布式锁
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*
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* @param lockKey 锁
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* @param requestId 请求标识
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* @param expireTime 超期时间
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* @return 是否获取成功
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*/
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private static boolean tryGetDistributedLock(Jedis redis, String lockKey, String requestId, int expireTime) {
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String result = redis.set(lockKey, requestId, SET_IF_NOT_EXIST, SET_WITH_EXPIRE_TIME, expireTime);
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if (LOCK_SUCCESS.equals(result)) {
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return true;
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}
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return false;
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}
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/**
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* 释放分布式锁
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*
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* @param lockKey 锁
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* @param requestId 请求标识
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* @return 是否释放成功
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*/
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public static boolean releaseDistributedLock(String lockKey, String requestId) {
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Jedis redis = null;
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try {
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redis = getJedis();
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String script = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return 0 end";
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Object result = redis.eval(script, Collections.singletonList(lockKey), Collections.singletonList(requestId));
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if (RELEASE_SUCCESS.equals(result)) {
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return true;
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}
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return false;
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} finally {
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if (redis != null) {
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redis.close();
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}
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}
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}
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}
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