2. Redisson源码剖析-公平锁的可重入加锁的源码剖析

1. 公平锁加锁的源码在RedissonFairLock

KEYS = Arrays.<Object>asList(getName(), threadsQueueName, timeoutSetName)
KEYS[1] = getName() = 锁的名字，“anyLock”
KEYS[2] = threadsQueueName = redisson_lock_queue:{anyLock}，基于redis的数据结构实现的一个队列
KEYS[3] = timeoutSetName = redisson_lock_timeout:{anyLock}，基于redis的数据结构实现的一个Set数据集合，有序集合，可以自动按照你给每个数据指定的一个分数（score）来进行排序

ARGV =  internalLockLeaseTime, getLockName(threadId), currentTime + threadWaitTime, currentTime
ARGV[1] = 30000毫秒
ARGV[2] = UUID:threadId
ARGV[3] = 当前时间（10:00:00） + 5000毫秒 = 10:00:05
ARGV[4] = 当前时间（10:00:00）

代码片段一、

@Override
<T> RFuture<T> tryLockInnerAsync(long leaseTime, TimeUnit unit, long threadId, RedisStrictCommand<T> command) {
    internalLockLeaseTime = unit.toMillis(leaseTime);


    long currentTime = System.currentTimeMillis();
    if (command == RedisCommands.EVAL_NULL_BOOLEAN) {
        return commandExecutor.evalWriteAsync(getName(), LongCodec.INSTANCE, command,
                // remove stale threads
                "while true do "
                + "local firstThreadId2 = redis.call('lindex', KEYS[2], 0);"
                + "if firstThreadId2 == false then "
                    + "break;"
                + "end; "
                + "local timeout = tonumber(redis.call('zscore', KEYS[3], firstThreadId2));"
                + "if timeout <= tonumber(ARGV[3]) then "
                    + "redis.call('zrem', KEYS[3], firstThreadId2); "
                    + "redis.call('lpop', KEYS[2]); "
                + "else "
                    + "break;"
                + "end; "
              + "end;"
                + 
                
                "if (redis.call('exists', KEYS[1]) == 0) and ((redis.call('exists', KEYS[2]) == 0) "
                        + "or (redis.call('lindex', KEYS[2], 0) == ARGV[2])) then " +
                        "redis.call('lpop', KEYS[2]); " +
                        "redis.call('zrem', KEYS[3], ARGV[2]); " +
                        "redis.call('hset', KEYS[1], ARGV[2], 1); " +
                        "redis.call('pexpire', KEYS[1], ARGV[1]); " +
                        "return nil; " +
                    "end; " +
                    "if (redis.call('hexists', KEYS[1], ARGV[2]) == 1) then " +
                        "redis.call('hincrby', KEYS[1], ARGV[2], 1); " +
                        "redis.call('pexpire', KEYS[1], ARGV[1]); " +
                        "return nil; " +
                    "end; " +
                    "return 1;", 
                Arrays.<Object>asList(getName(), threadsQueueName, timeoutSetName), 
                internalLockLeaseTime, getLockName(threadId), currentTime);
    }
    
    if (command == RedisCommands.EVAL_LONG) {
        return commandExecutor.evalWriteAsync(getName(), LongCodec.INSTANCE, command,
                // remove stale threads
                // 1. 首先会进入到这里，lindex redisson_lock_queue:{anyLock} 0，获取队列中的第一个元素
                "while true do "
                + "local firstThreadId2 = redis.call('lindex', KEYS[2], 0);”
                + "if firstThreadId2 == false then "
                    + "break;"
                + "end; “
                // 判断他的timeout时间是否大于当前时间，假设当前时间为10：00：08，不成立，直接跳出死循环
                + "local timeout = tonumber(redis.call('zscore', KEYS[3], firstThreadId2));"
                + "if timeout <= tonumber(ARGV[4]) then "
                    + "redis.call('zrem', KEYS[3], firstThreadId2); "
                    + "redis.call('lpop', KEYS[2]); "
                + "else "
                    + "break;"
                + "end; "
              + "end;"
                    // 1. Exists anyLock,肯定是存在的，所以条件不成立
                  + "if (redis.call('exists', KEYS[1]) == 0) and ((redis.call('exists', KEYS[2]) == 0) "
                        + "or (redis.call('lindex', KEYS[2], 0) == ARGV[2])) then " +
                        "redis.call('lpop', KEYS[2]); " +
                        "redis.call('zrem', KEYS[3], ARGV[2]); " +
                        "redis.call('hset', KEYS[1], ARGV[2], 1); " +
                        "redis.call('pexpire', KEYS[1], ARGV[1]); " +
                        "return nil; " +
                    "end; “ +
                    // 1. Hexists anyLock UUID_01:thread_01 ,判断anyLock的hash中是否存在一个UUID_01:threadId_01的key，当前这个锁是否是客户端A加的锁，条件是成立的
                    "if (redis.call('hexists', KEYS[1], ARGV[2]) == 1) then “ +
                        // hincrby  anyLock UUID_01:threadId_01 累加1
                        "redis.call('hincrby', KEYS[1], ARGV[2], 1); “ +
                        // 更新anyLock的生存周期为30000毫秒
                        "redis.call('pexpire', KEYS[1], ARGV[1]); “ +
                        // 返回nil
                        "return nil; " +
                    "end; " +
                        
                    "local firstThreadId = redis.call('lindex', KEYS[2], 0); " +
                    "local ttl; " + 
                    "if firstThreadId ~= false and firstThreadId ~= ARGV[2] then " + 
                        "ttl = tonumber(redis.call('zscore', KEYS[3], firstThreadId)) - tonumber(ARGV[4]);" + 
                    "else "
                      + "ttl = redis.call('pttl', KEYS[1]);" + 
                    "end; " + 
                        
                    "local timeout = ttl + tonumber(ARGV[3]);" + 
                    "if redis.call('zadd', KEYS[3], timeout, ARGV[2]) == 1 then " +
                        "redis.call('rpush', KEYS[2], ARGV[2]);" +
                    "end; " +
                    "return ttl;", 
                    Arrays.<Object>asList(getName(), threadsQueueName, timeoutSetName), 
                                internalLockLeaseTime, getLockName(threadId), currentTime + threadWaitTime, currentTime);
    }
    
    throw new IllegalArgumentException();
}