一篇吃透Redis与Redisson分布式锁

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/**
* 原生分布式锁 开始
* 1、原子加锁 设置过期时间，防止宕机死锁
* 2、原子解锁：需要判断是不是自己的锁
*/
String uuid = CommonUtil.generateUUID();
String lockKey = "lock:coupon:"+couponId;
Boolean nativeLock=redisTemplate.opsForValue().setIfAbsent(lockKey,uuid,Duration.ofSeconds(30));
    if(nativeLock){
      //加锁成功
      log.info("加锁：{}",nativeLock);
      try {
           //执行业务  TODO
        }finally {
           String script = "if redis.call('get',KEYS[1]) == ARGV[1] then return redis.call('del',KEYS[1]) else return 0 end";
​
                Integer result = redisTemplate.execute(new DefaultRedisScript<>(script, Integer.class), Arrays.asList(lockKey), uuid);
                log.info("解锁：{}",result);
            }
​
        }else {
            //加锁失败，睡眠100毫秒，自旋重试
            try {
                TimeUnit.MILLISECONDS.sleep(100L);
            } catch (InterruptedException e) { }
            return addCoupon( couponId, couponCategory);
        }
        //原生分布式锁 结束

String lockKey = "lock:coupon:"+couponId+":"+loginUser.getId();
RLock rLock = redissonClient.getLock((lockKey));
//多个线程进入，会阻塞等待释放锁
rLock.lock();
log.info("领卷接口加锁成功：{}",Thread.currentThread().getId());
try{
    //业务逻辑
}finally {
    rLock.unlock();
    log.info("解锁成功");
}

Timeout task = commandExecutor.getConnectionManager().newTimeout(new TimerTask() {
    @Override
    public void run(Timeout timeout) throws Exception {
        
        RFuture<Boolean> future = renewExpirationAsync(threadId);
        
        future.addListener(new FutureListener<Boolean>() {
            @Override
            public void operationComplete(Future<Boolean> future) throws Exception {
                expirationRenewalMap.remove(getEntryName());
                if (!future.isSuccess()) {
                    log.error("Can't update lock " + getName() + " expiration", future.cause());
                    return;
                }
                
                if (future.getNow()) {
                    // reschedule itself
                    scheduleExpirationRenewal(threadId);
                }
            }
        });
    }
​
}, internalLockLeaseTime / 3, TimeUnit.MILLISECONDS);

protected RFuture<Boolean> renewExpirationAsync(long threadId) {
    return commandExecutor.evalWriteAsync(getName(), LongCodec.INSTANCE, RedisCommands.EVAL_BOOLEAN,
            "if (redis.call('hexists', KEYS[1], ARGV[2]) == 1) then " +
                "redis.call('pexpire', KEYS[1], ARGV[1]); " +
                "return 1; " +
            "end; " +
            "return 0;",
        Collections.<Object>singletonList(getName()), 
        internalLockLeaseTime, getLockName(threadId));
}

"if (redis.call('exists', KEYS[1]) == 0) then " +
    "redis.call('publish', KEYS[2], ARGV[1]); " +
    "return 1; " +
"end;" +
判断锁在不在，不在的话，说明执行完了，发布解锁消息
"if (redis.call('hexists', KEYS[1], ARGV[3]) == 0) then " +
                    "return nil;" +
                "end; " 
 锁在，要解锁，但是要判断是不是他的锁，参数3是uuid+threadId，这里也是我们原生分布式锁中finally中判断逻辑，防止误删
 (当然误删场景是在锁过期之后发生的，看门狗机制这里应该不会发生，但是不是只有看门狗机制的，有直接配置过期时间，不用看门狗机制
 下面会讲)
 "local counter = redis.call('hincrby', KEYS[1], ARGV[3], -1); " +
 "if (counter > 0) then " +
                    "redis.call('pexpire', KEYS[1], ARGV[2]); " +
                    "return 0; " +
                "else " +
                    "redis.call('del', KEYS[1]); " +
                    "redis.call('publish', KEYS[2], ARGV[1]); " +
                    "return 1; "+
                "end; " +
    //counter是什么。还记得加锁时候的hset吗，hash结构也有key value，key是uuid+threadId，vlaue我们设置为1了
    但是上面还有可重入锁的设计，1自增为2，那么解锁的时候，也要自增-1，hincry -1，等于0的时候，才算锁用完了，
    不等于0，直接return什么也不做，等待其他线程解锁，知道hash的value==0.才执行publish，发布消息到信道 

String lockKey = "lock:coupon:"+couponId+":"+loginUser.getId();
RLock rLock = redissonClient.getLock((lockKey));
//多个线程进入，会阻塞等待释放锁
rLock.lock();

@Override
public boolean tryLock(long waitTime, long leaseTime, TimeUnit unit)

//key1是短链码，ARGV[1]是accountNo,ARGV[2]是过期时间
String script = "if redis.call('EXISTS',KEYS[1])==0 then redis.call('set',KEYS[1],ARGV[1]); redis.call('expire',KEYS[1],ARGV[2]); return 1;" +
                " elseif redis.call('get',KEYS[1]) == ARGV[1] then return 2;" +
                " else return 0; end;";
​
Long result = redisTemplate.execute(new
                DefaultRedisScript<>(script, Long.class), Arrays.asList(code), accountNO,100);