Redisson分布式锁和同步器详解-官方原版

一、锁定

基于Redis的Java分布式可重入锁对象，并实现了锁接口。

如果获取锁的Redisson实例崩溃，则此类锁可能会在获取状态下永久挂起。为了避免这种Redisson维护锁看门狗，当锁持有者Redisson实例处于活动状态时，它会延长锁的到期时间。默认情况下，锁看门狗超时为30秒，可以通过Config.lockWatchdogTimeout设置进行更改。

可以定义锁获取期间的leaseTime参数。在指定的时间间隔后，锁定的锁将自动释放。

RLock对象的行为符合Java Lock规范。这意味着只有锁所有者线程才能解锁它，否则将引发IllegalMonitorStateException。否则，请考虑使用RSemaphore对象。

代码示例：

RLock lock = redisson.getLock("myLock");// traditional lock method
lock.lock();// or acquire lock and automatically unlock it after 10 seconds
lock.lock(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
boolean res = lock.tryLock(100, 10, TimeUnit.SECONDS);
if (res) {try {...} finally {lock.unlock();}
}

异步接口用法的代码示例：

RLock lock = redisson.getLock("myLock");RFuture<Void> lockFuture = lock.lockAsync();// or acquire lock and automatically unlock it after 10 seconds
RFuture<Void> lockFuture = lock.lockAsync(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
RFuture<Boolean> lockFuture = lock.tryLockAsync(100, 10, TimeUnit.SECONDS);lockFuture.whenComplete((res, exception) -> {// ...lock.unlockAsync();
});

反应式接口用法的代码示例：

RedissonReactiveClient redisson = redissonClient.reactive();
RLockReactive lock = redisson.getLock("myLock");Mono<Void> lockMono = lock.lock();// or acquire lock and automatically unlock it after 10 seconds
Mono<Void> lockMono = lock.lock(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
Mono<Boolean> lockMono = lock.tryLock(100, 10, TimeUnit.SECONDS);lockMono.doOnNext(res -> {// ...
})
.doFinally(lock.unlock())
.subscribe();

RxJava3 接口使用的代码示例：

RedissonRxClient redisson = redissonClient.rxJava();
RLockRx lock = redisson.getLock("myLock");Completable lockRes = lock.lock();// or acquire lock and automatically unlock it after 10 seconds
Completable lockRes = lock.lock(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
Single<Boolean> lockRes = lock.tryLock(100, 10, TimeUnit.SECONDS);lockRes.doOnSuccess(res -> {// ...
})
.doFinally(lock.unlock())
.subscribe();

二、公平锁定

基于Redis的分布式可重入公平Java锁对象实现了锁接口。

公平锁保证线程将按照请求的顺序获取它。所有等待的线程都将排队，如果某个线程已死亡，Redisson将等待其返回5秒。例如，如果5个线程由于某种原因而死亡，那么延迟将为25秒。

如果获取锁的Redisson实例崩溃，则此类锁可能会在获取状态下永久挂起。为了避免这种Redisson维护锁看门狗，当锁持有者Redisson实例处于活动状态时，它会延长锁的到期时间。默认情况下，锁看门狗超时为30秒，可以通过Config.lockWatchdogTimeout设置进行更改。

可以定义锁获取期间的leaseTime参数。在指定的时间间隔后，锁定的锁将自动释放。

RLock对象的行为符合Java Lock规范。这意味着只有锁所有者线程才能解锁它，否则将引发IllegalMonitorStateException。否则，请考虑使用RSemaphore对象。

代码示例：

RLock lock = redisson.getFairLock("myLock");// traditional lock method
lock.lock();// or acquire lock and automatically unlock it after 10 seconds
lock.lock(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
boolean res = lock.tryLock(100, 10, TimeUnit.SECONDS);
if (res) {try {...} finally {lock.unlock();}
}

异步接口用法的代码示例：

RLock lock = redisson.getFairLock("myLock");RFuture<Void> lockFuture = lock.lockAsync();// or acquire lock and automatically unlock it after 10 seconds
RFuture<Void> lockFuture = lock.lockAsync(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
RFuture<Boolean> lockFuture = lock.tryLockAsync(100, 10, TimeUnit.SECONDS);lockFuture.whenComplete((res, exception) -> {// ...lock.unlockAsync();
});

Reactive接口 用法的代码示例:

RedissonReactiveClient redisson = redissonClient.reactive();
RLockReactive lock = redisson.getFairLock("myLock");Mono<Void> lockMono = lock.lock();// or acquire lock and automatically unlock it after 10 seconds
Mono<Void> lockMono = lock.lock(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
Mono<Boolean> lockMono = lock.tryLock(100, 10, TimeUnit.SECONDS);lockMono.doOnNext(res -> {// ...
})
.doFinally(lock.unlock())
.subscribe();

RxJava3 接口使用的代码示例：

RedissonRxClient redisson = redissonClient.rxJava();
RLockRx lock = redisson.getFairLock("myLock");Completable lockRes = lock.lock();// or acquire lock and automatically unlock it after 10 seconds
Completable lockRes = lock.lock(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
Single<Boolean> lockRes = lock.tryLock(100, 10, TimeUnit.SECONDS);lockRes.doOnSuccess(res -> {// ...
})
.doFinally(lock.unlock())
.subscribe();

三、多重锁

基于Redis的分布式MultiLock对象允许将Lock对象分组，并将其作为单个锁处理。每个RLock对象可能属于不同的Redisson实例。

如果获取MultiLock的Redisson实例崩溃，那么这样的MultiLock可能会永远挂在获取状态。为了避免这种Redisson维护锁看门狗，当锁持有者Redisson实例处于活动状态时，它会延长锁的到期时间。默认情况下，锁看门狗超时为30秒，可以通过Config.lockWatchdogTimeout设置进行更改。

可以定义锁获取期间的leaseTime参数。在指定的时间间隔后，锁定的锁将自动释放。

MultiLock对象的行为符合Java Lock规范。这意味着只有锁所有者线程才能解锁它，否则将引发IllegalMonitorStateException。否则，请考虑使用RSemaphore对象。

代码示例：

RLock lock1 = redisson1.getLock("lock1");
RLock lock2 = redisson2.getLock("lock2");
RLock lock3 = redisson3.getLock("lock3");RLock multiLock = anyRedisson.getMultiLock(lock1, lock2, lock3);// traditional lock method
multiLock.lock();// or acquire lock and automatically unlock it after 10 seconds
multiLock.lock(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
boolean res = multiLock.tryLock(100, 10, TimeUnit.SECONDS);
if (res) {try {...} finally {multiLock.unlock();}
}

异步接口用法的代码示例：

RLock lock1 = redisson1.getLock("lock1");
RLock lock2 = redisson2.getLock("lock2");
RLock lock3 = redisson3.getLock("lock3");RLock multiLock = anyRedisson.getMultiLock(lock1, lock2, lock3);RFuture<Void> lockFuture = multiLock.lockAsync();// or acquire lock and automatically unlock it after 10 seconds
RFuture<Void> lockFuture = multiLock.lockAsync(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
RFuture<Boolean> lockFuture = multiLock.tryLockAsync(100, 10, TimeUnit.SECONDS);lockFuture.whenComplete((res, exception) -> {// ...multiLock.unlockAsync();
});

反应式接口用法的代码示例：

RedissonReactiveClient anyRedisson = redissonClient.reactive();RLockReactive lock1 = redisson1.getLock("lock1");
RLockReactive lock2 = redisson2.getLock("lock2");
RLockReactive lock3 = redisson3.getLock("lock3");RLockReactive multiLock = anyRedisson.getMultiLock(lock1, lock2, lock3);Mono<Void> lockMono = multiLock.lock();// or acquire lock and automatically unlock it after 10 seconds
Mono<Void> lockMono = multiLock.lock(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
Mono<Boolean> lockMono = multiLock.tryLock(100, 10, TimeUnit.SECONDS);lockMono.doOnNext(res -> {// ...
})
.doFinally(multiLock.unlock())
.subscribe();

RxJava3 接口使用的代码示例：

RedissonRxClient anyRedisson = redissonClient.rxJava();RLockRx lock1 = redisson1.getLock("lock1");
RLockRx lock2 = redisson2.getLock("lock2");
RLockRx lock3 = redisson3.getLock("lock3");RLockRx multiLock = anyRedisson.getMultiLock(lock1, lock2, lock3);Completable lockRes = multiLock.lock();// or acquire lock and automatically unlock it after 10 seconds
Completable lockRes = multiLock.lock(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
Single<Boolean> lockRes = multiLock.tryLock(100, 10, TimeUnit.SECONDS);lockRes.doOnSuccess(res -> {// ...
})
.doFinally(multiLock.unlock())
.subscribe();

四、读写锁定

基于Redis的Java分布式可重入读写锁对象实现了读写锁接口。读和写锁都实现RLock接口。

只允许有多个ReadLock所有者和一个WriteLock所有者。

如果获取锁的Redisson实例崩溃，则此类锁可能会在获取状态下永久挂起。为了避免这种Redisson维护锁看门狗，当锁持有者Redisson实例处于活动状态时，它会延长锁的到期时间。默认情况下，锁看门狗超时为30秒，可以通过Config.lockWatchdogTimeout设置进行更改。

此外，Redisson允许在获取锁期间指定leaseTime参数。在指定的时间间隔后，锁定的锁将自动释放。

RLock对象的行为符合Java Lock规范。这意味着只有锁所有者线程才能解锁它，否则将引发IllegalMonitorStateException。否则，请考虑使用RSemaphore对象。

代码示例：

RReadWriteLock rwlock = redisson.getReadWriteLock("myLock");RLock lock = rwlock.readLock();
// or
RLock lock = rwlock.writeLock();// traditional lock method
lock.lock();// or acquire lock and automatically unlock it after 10 seconds
lock.lock(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
boolean res = lock.tryLock(100, 10, TimeUnit.SECONDS);
if (res) {try {...} finally {lock.unlock();}
}

异步接口用法的代码示例：

RReadWriteLock rwlock = redisson.getReadWriteLock("myLock");RLock lock = rwlock.readLock();
// or
RLock lock = rwlock.writeLock();RFuture<Void> lockFuture = lock.lockAsync();// or acquire lock and automatically unlock it after 10 seconds
RFuture<Void> lockFuture = lock.lockAsync(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
RFuture<Boolean> lockFuture = lock.tryLockAsync(100, 10, TimeUnit.SECONDS);lockFuture.whenComplete((res, exception) -> {// ...lock.unlockAsync();
});

反应式接口用法的代码示例：

RedissonReactiveClient redisson = redissonClient.reactive();RReadWriteLockReactive rwlock = redisson.getReadWriteLock("myLock");RLockReactive lock = rwlock.readLock();
// or
RLockReactive lock = rwlock.writeLock();Mono<Void> lockMono = lock.lock();// or acquire lock and automatically unlock it after 10 seconds
Mono<Void> lockMono = lock.lock(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
Mono<Boolean> lockMono = lock.tryLock(100, 10, TimeUnit.SECONDS);lockMono.doOnNext(res -> {// ...
})
.doFinally(lock.unlock())
.subscribe();

RxJava3 接口使用的代码示例：

RedissonRxClient redisson = redissonClient.rxJava();RReadWriteLockRx rwlock = redisson.getReadWriteLock("myLock");RLockRx lock = rwlock.readLock();
// or
RLockRx lock = rwlock.writeLock();Completable lockRes = lock.lock();// or acquire lock and automatically unlock it after 10 seconds
Completable lockRes = lock.lock(10, TimeUnit.SECONDS);// or wait for lock aquisition up to 100 seconds 
// and automatically unlock it after 10 seconds
Single<Boolean> lockRes = lock.tryLock(100, 10, TimeUnit.SECONDS);lockRes.doOnSuccess(res -> {// ...
})
.doFinally(lock.unlock())
.subscribe();

五、信号量

基于Redis的分布式Java信号量对象，类似于信号量对象。

可以在使用前初始化，但这不是必需的，通过trySetPermissions（permissions）方法获得可用的许可量。

代码示例：

RSemaphore semaphore = redisson.getSemaphore("mySemaphore");// acquire single permit
semaphore.acquire();// or acquire 10 permits
semaphore.acquire(10);// or try to acquire permit
boolean res = semaphore.tryAcquire();// or try to acquire permit or wait up to 15 seconds
boolean res = semaphore.tryAcquire(15, TimeUnit.SECONDS);// or try to acquire 10 permit
boolean res = semaphore.tryAcquire(10);// or try to acquire 10 permits or wait up to 15 seconds
boolean res = semaphore.tryAcquire(10, 15, TimeUnit.SECONDS);
if (res) {try {...} finally {semaphore.release();}
}

异步接口用法的代码示例：

RSemaphore semaphore = redisson.getSemaphore("mySemaphore");// acquire single permit
RFuture<Void> acquireFuture = semaphore.acquireAsync();// or acquire 10 permits
RFuture<Void> acquireFuture = semaphore.acquireAsync(10);// or try to acquire permit
RFuture<Boolean> acquireFuture = semaphore.tryAcquireAsync();// or try to acquire permit or wait up to 15 seconds
RFuture<Boolean> acquireFuture = semaphore.tryAcquireAsync(15, TimeUnit.SECONDS);// or try to acquire 10 permit
RFuture<Boolean> acquireFuture = semaphore.tryAcquireAsync(10);// or try to acquire 10 permits or wait up to 15 seconds
RFuture<Boolean> acquireFuture = semaphore.tryAcquireAsync(10, 15, TimeUnit.SECONDS);acquireFuture.whenComplete((res, exception) -> {// ...semaphore.releaseAsync();
});

反应式接口用法的代码示例：

RedissonReactiveClient redisson = redissonClient.reactive();RSemaphoreReactive semaphore = redisson.getSemaphore("mySemaphore");// acquire single permit
Mono<Void> acquireMono = semaphore.acquire();// or acquire 10 permits
Mono<Void> acquireMono = semaphore.acquire(10);// or try to acquire permit
Mono<Boolean> acquireMono = semaphore.tryAcquire();// or try to acquire permit or wait up to 15 seconds
Mono<Boolean> acquireMono = semaphore.tryAcquire(15, TimeUnit.SECONDS);// or try to acquire 10 permit
Mono<Boolean> acquireMono = semaphore.tryAcquire(10);// or try to acquire 10 permits or wait up to 15 seconds
Mono<Boolean> acquireMono = semaphore.tryAcquire(10, 15, TimeUnit.SECONDS);acquireMono.doOnNext(res -> {// ...
})
.doFinally(semaphore.release())
.subscribe();

RxJava3 接口使用的代码示例：

RedissonRxClient redisson = redissonClient.rxJava();RSemaphoreRx semaphore = redisson.getSemaphore("mySemaphore");// acquire single permit
Completable acquireRx = semaphore.acquire();// or acquire 10 permits
Completable acquireRx = semaphore.acquire(10);// or try to acquire permit
Single<Boolean> acquireRx = semaphore.tryAcquire();// or try to acquire permit or wait up to 15 seconds
Single<Boolean> acquireRx = semaphore.tryAcquire(15, TimeUnit.SECONDS);// or try to acquire 10 permit
Single<Boolean> acquireRx = semaphore.tryAcquire(10);// or try to acquire 10 permits or wait up to 15 seconds
Single<Boolean> acquireRx = semaphore.tryAcquire(10, 15, TimeUnit.SECONDS);acquireRx.doOnSuccess(res -> {// ...
})
.doFinally(semaphore.release())
.subscribe();