Redis分布式锁实现实例
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2022-07-16 13:12:40
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今天面试官问Redis分布式锁实现代码简单步骤,其中有一点面试官坚持说set操作和超时设置必须是2行代码,我当时懵了一下,我只能说这违反了“原子”操作,以下是我的实现示例代码:
上锁:
释放锁:
spring boot之Redis分布式锁示例代码
上锁:
@Override public boolean lock(String lockKey, String requestId, Long expireTime) { Assert.isTrue(StringUtils.isNotBlank(lockKey), "lockKey不能为空"); Assert.isTrue(StringUtils.isNotBlank(requestId), "请求标识不能为空"); Object result = stringRedisTemplate.execute(new RedisCallback<Boolean>() { @Override public Boolean doInRedis(RedisConnection connection) throws DataAccessException { Expiration expiration = Expiration.milliseconds(null == expireTime ? 1000L * 60 : expireTime); byte[] key = lockKey.getBytes(Charset.forName("UTF-8")); byte[] value = requestId.getBytes(Charset.forName("UTF-8")); return connection.set(key, value, expiration, SetOption.SET_IF_ABSENT); } }); return (null == result) ? false : result.equals(true); }
释放锁:
@Override public boolean unlock(String lockKey, String requestId) { Assert.isTrue(StringUtils.isNotBlank(lockKey), "lockKey不能为空"); Assert.isTrue(StringUtils.isNotBlank(requestId), "请求标识不能为空"); String lua = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return 0 end"; Object result = stringRedisTemplate.execute(new RedisCallback<Boolean>() { @Override public Boolean doInRedis(RedisConnection connection) throws DataAccessException { byte[] script = lua.getBytes(Charset.forName("UTF-8")); byte[] key = lockKey.getBytes(Charset.forName("UTF-8")); byte[] value = requestId.getBytes(Charset.forName("UTF-8")); Long result = connection.eval(script, ReturnType.INTEGER, 1, key, value); return (null == result ? false : result.equals(1L)); } }); return (null == result) ? false : result.equals(true); /* 若redis是2.6.0以下版本,则不支持lua脚本,只能降级采用redisTemplate.delete解锁,但不能保证原子操作 */ }
spring boot之Redis分布式锁示例代码