分布式锁-redis

Posted 2020-11-22 wanhua.wu

 

@Autowired
    private RedisTemplate<String, Object> redisTemplate;


/**
     * 获取分布式锁 - 过期时间
     * @param key
     * @param expireTime 毫秒
     * @return
     */
    public Object getExpiredLock(String key, Long expireTime) {
        Long value = System.currentTimeMillis() + expireTime;
        return redisTemplate.execute((RedisCallback) connection -> {
            int count = 3;
            while (count > 0) {
                try {
                    JedisCommands commands = (JedisCommands) connection.getNativeConnection();
                    return commands.set(key, String.valueOf(value), "NX", "PX", expireTime);
                } catch (Exception e) {
                    logger.error("getExpiredLock exception key={}, count={}:", key, count, e);
                    count--;
                }
            }
            return null;
        });
    }


/**
     * 获取分布式锁 - 过期时间，value
     * @param key
     * @param expireTime
     * @return
     */
    public Object getExpiredLock(String key, Long expireTime, String value) {
        return redisTemplate.execute((RedisCallback) connection -> {
            int count = 3;
            while (count > 0) {
                try {
                    JedisCommands commands = (JedisCommands) connection.getNativeConnection();
                    return commands.set(key, value, "NX", "PX", expireTime);
                } catch (Exception e) {
                    logger.error("getExpiredLock exception key={}, count={}:", key, count, e);
                    count--;
                }
            }
            return null;
        });
    }

/**
     * 获取分布式锁value
     * @param key
     * @return
     */
    public Object getValue4ExpiredLock(String key) {
        return redisTemplate.execute((RedisCallback) connection -> {
            int count = 3;
            while (count > 0) {
                try {
                    JedisCommands commands = (JedisCommands) connection.getNativeConnection();
                    return commands.get(key);
                } catch (Exception e) {
                    logger.error("getExpiredLock exception key={}, count={}:", key, count, e);
                    count--;
                }
            }
            return null;
        });
    }


/**
     * 删除任务队列锁
     * @param lockKey
     */
    public void deleteLock(String lockKey) {
        int count = 3;
        while (count > 0) {
            try {
                if (redisTemplate.hasKey(lockKey) && Long.valueOf(""+getValue4ExpiredLock(lockKey)) > System.currentTimeMillis()) {
                    // 当前时间比该锁对应的value小，说明未过期，并占有该锁，可以直接删除
                    redisTemplate.delete(lockKey);
                    logger.info("删除list锁:{}", lockKey);
                } else {
                    logger.info("任务锁已过期, taskListLockKey={}", lockKey);
                }
                break;
            } catch (Exception e) {
                logger.error("deleteLock count={}", count, e);
                count--;
            }
        }

    }

　　

        // 获取分布式锁
        if (redisService.getExpiredLock(key, 5000L) == null) {
            return;
        }    


        // 删除分布式锁
         redisService.deleteLock(key);