MultiLock

MultiLock：将多个锁合并为一个大锁，对一个大锁进行统一的申请加锁以及释放锁，一次性锁定多个资源，再去处理一些事情，然后事后一次性释放所有的资源对应的锁。

代码示例：

Config config = new Config();
config.useClusterServers()
    .addNodeAddress("redis://192.168.31.114:7001")
    .addNodeAddress("redis://192.168.31.184:7002");

RedissonClient redisson = Redisson.create(config);

RLock lock1 = redisson.getLock("lock1");
RLock lock2 = redisson.getLock("lock2");
RLock lock3 = redisson.getLock("lock3");

RedissonMultiLock lock = new RedissonMultiLock(lock1, lock2, lock3);
// locks: lock1 lock2 lock3
lock.lock();
lock.unlock();

核心源码：

根据锁的个数，计算出基础的等待时间。

long baseWaitTime = locks.size() * 1500;

循环尝试获取锁，直到获取锁成功后返回。

while (true) {
    if (tryLock(waitTime, leaseTime, unit)) {
        return;
    }
}

调用RedissonLock的tryLock方法，尝试获取锁，如果获取锁成功，把锁添加到集合。

List<RLock> acquiredLocks = new ArrayList<RLock>(locks.size());
lockAcquired = lock.tryLock();
acquiredLocks.add(lock);

如果获取锁超时就会退出，重新再次死循环尝试获取锁。

if (locks.size() - acquiredLocks.size() == failedLocksLimit()) {
    break;
}

if (failedLocksLimit == 0) {
    unlockInner(acquiredLocks);
    if (waitTime == -1 && leaseTime == -1) {
        return false;
    }
    failedLocksLimit = failedLocksLimit();
    acquiredLocks.clear();
    // reset iterator
    while (iterator.hasPrevious()) {
        iterator.previous();
    }
} else {
    failedLocksLimit--;
}