redisson 基于 org.redisson:redisson-spring-data-27:3.27.2 版本
在 java 中，操作 redis 一般都会选择 redisson 框架, 我们需要了解常用功能的实现原理, 这次来介绍 RedissonMultiLock。
使用方式
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| @Test
void testMultiLock() {
RLock lock1 = redissonClient.getLock("lock1");
RLock lock2 = redissonClient.getLock("lock2");
RLock lock = redissonClient.getMultiLock(lock1, lock2);
try {
lock.lock();
ThreadUtil.sleep(30, TimeUnit.SECONDS);
System.out.println("xxx");
} finally {
lock.unlock();
}
}
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在实际使用过程中，可能一次性获取多个锁， 那么你应该使用 RedissonMultiLock 来简化你的操作。
lock
源码位置: org.redisson.RedissonMultiLock#tryLock
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| // lock 最终会调用 tryLock 方法
@Override
public boolean tryLock(long waitTime, long leaseTime, TimeUnit unit) throws InterruptedException {
...
int failedLocksLimit = failedLocksLimit();
List<RLock> acquiredLocks = new ArrayList<>(locks.size());
// 遍历获取每个锁
for (ListIterator<RLock> iterator = locks.listIterator(); iterator.hasNext();) {
RLock lock = iterator.next();
boolean lockAcquired;
try {
if (waitTime <= 0 && leaseTime <= 0) {
lockAcquired = lock.tryLock();
} else {
long awaitTime = Math.min(lockWaitTime, remainTime);
// 尝试获取锁
lockAcquired = lock.tryLock(awaitTime, newLeaseTime, TimeUnit.MILLISECONDS);
}
} catch (RedisResponseTimeoutException e) {
unlockInner(Arrays.asList(lock));
lockAcquired = false;
} catch (Exception e) {
lockAcquired = false;
}
if (lockAcquired) {
// 获取锁成功
acquiredLocks.add(lock);
} else {
// 判断容错次数, failedLocksLimit() 默认为 0
if (locks.size() - acquiredLocks.size() == failedLocksLimit()) {
break;
}
// 获取锁失败
if (failedLocksLimit == 0) {
// 释放之前的锁
unlockInner(acquiredLocks);
if (waitTime <= 0) {
return false;
}
failedLocksLimit = failedLocksLimit();
acquiredLocks.clear();
// reset iterator
while (iterator.hasPrevious()) {
iterator.previous();
}
} else {
failedLocksLimit--;
}
}
...
}
return true;
}
|
unlock
源码位置: org.redisson.RedissonMultiLock#unlock
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| @Override
public void unlock() {
// 遍历每个锁，然后解锁
locks.forEach(Lock::unlock);
}
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