Redis分布式锁

Foreward

正好有业务场景需要使用分布式锁,读到这篇文章,非常好,做下摘录.

• Redis 分布式锁的正确实现方式（ Java 版 ）

• Set Command

Code

• RedisKey设置

public class RedisKey {
    /**
     * 正则表达式.
     */
    public static final String REGEX = "\\{[a-zA-Z0-9]*\\}";
    /**
     * 全局独自执行任务.
     */
    public static final String EXEC_LOCK = "exec:lock";
    /**
     * 和锁配合使用,每个客户端一个标志.
     */
    private static final String OWNER_ID = UUID.randomUUID().toString();
    /**
     * 获取执行指定任务权限key.
     *
     * @return
     */
    public static String getExecLock(Object... objs) {
        return replaceKey(EXEC_LOCK, objs);
    }
    private static String replaceKey(String key, Object... objs) {
        for (Object obj : objs) {
            key = key.replaceFirst(REGEX, String.valueOf(obj));
        }
        return key;
    }
    public static String getOwnerId() {
        return OWNER_ID;
    }
}

• RedisService服务工具类

@Slf4j
public class RedisService {  
    /**
     * Only set the key if it does not already exist.
     */
    private static final String SET_IF_NOT_EXIST = "NX";
    /**
     * Set the specified expire time, in milliseconds.
     */
    private static final String SET_WITH_EXPIRE_MILL_TIME = "PX";
    /**
     * Set the specified expire time, in seconds.
     */
    private static final String SET_WITH_EXPIRE_SECOND_TIME = "EX";
    private static final String LOCK_SUCCESS = "OK";
    private static final Long RELEASE_SUCCESS = 1L;
    
    /**
     * 设置分布式锁.(过期时间毫秒)
     * @param lockKey    锁的名称.
     * @param requestId  持锁人ID.
     * @param expireTime 锁的超时时间.
     * @return 是否获取锁.
     */
    public synchronized boolean tryGetDistributeLock(String lockKey, String requestId, int expireTime) {
        log.debug("lock key: {}, ownerId: {}, expire time: {}", lockKey, requestId, expireTime);
        String result = jedis.set(lockKey, requestId, SET_IF_NOT_EXIST, SET_WITH_EXPIRE_MILL_TIME, expireTime);
        if (LOCK_SUCCESS.equals(result)) {
            return true;
        }
        return false;
    }

    /**
     * 释放分布式锁.
     *
     * @param lockKey   锁
     * @param requestId 请求标识
     * @return 是否释放成功.
     */
    public synchronized boolean releaseDistributedLock(String lockKey, String requestId) {
        log.debug("release lock key: {}, ownerId: {}, expire time: {}", lockKey, requestId);
        String script = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return 0 end";
        Object result = jedis.eval(script, Collections.singletonList(lockKey), Collections.singletonList(requestId));
        if (RELEASE_SUCCESS.equals(result)) {
            return true;
        }
        return false;
    }
}