【RedissonClient】tryLock() 为什么做到了服务崩溃，lock也不会一直被占有？

源码解释：

org.redisson.RedissonLock#tryAcquireOnceAsync

    private RFuture tryAcquireOnceAsync(long leaseTime, TimeUnit unit, final long threadId) {
        if (leaseTime != -1) {
            return tryLockInnerAsync(leaseTime, unit, threadId, RedisCommands.EVAL_NULL_BOOLEAN);
        }
        RFuture ttlRemainingFuture = tryLockInnerAsync(commandExecutor.getConnectionManager().getCfg().getLockWatchdogTimeout(), TimeUnit.MILLISECONDS, threadId, RedisCommands.EVAL_NULL_BOOLEAN);
        ttlRemainingFuture.addListener(new FutureListener() {
            @Override
            public void operationComplete(Future future) throws Exception {
                if (!future.isSuccess()) {
                    return;
                }

                Boolean ttlRemaining = future.getNow();
                // lock acquired  获取到lock后，方式刷新过期时间，unlock之前每次过期默认30秒
                if (ttlRemaining) {
                    scheduleExpirationRenewal(threadId);
                }
            }
        });
        return ttlRemainingFuture;
    }

重点就是上面那个注释：                // lock acquired  获取到lock后，方式刷新过期时间，unlock之前每10s设置一次过期（默认30秒）

其中的定时刷新器用到了：io.netty.util.HashedWheelTimer  我们后面分析，时间轮！！

 

具体10S间隔，30秒过期时间设置源码如下

    private void scheduleExpirationRenewal(final long threadId) {
        if (expirationRenewalMap.containsKey(getEntryName())) {
            return;
        }

        Timeout task = commandExecutor.getConnectionManager().newTimeout(new TimerTask() {
            @Override
            public void run(Timeout timeout) throws Exception {
                
                RFuture future = 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.