org.redisson.api

Interface RSemaphoreAsync

All Superinterfaces:

RExpirableAsync, RObjectAsync

All Known Subinterfaces:

RSemaphore

All Known Implementing Classes:

RedissonQueueSemaphore, RedissonSemaphore

public interface RSemaphoreAsync
extends RExpirableAsync

Distributed and concurrent implementation of Semaphore.

Works in non-fair mode. Therefore order of acquiring is unpredictable.

Author:

Nikita Koksharov

Method Summary

Modifier and Type	Method and Description
RFuture<Void>	acquireAsync() Acquires a permit from this semaphore.
RFuture<Void>	acquireAsync(int permits) Acquires the given number of permits, if they are available, and returns immediately, reducing the number of available permits by the given amount.
RFuture<Void>	reducePermitsAsync(int permits) Shrinks the number of available permits by the indicated reduction.
RFuture<Void>	releaseAsync() Releases a permit, returning it to the semaphore.
RFuture<Void>	releaseAsync(int permits) Releases the given number of permits, returning them to the semaphore.
RFuture<Boolean>	tryAcquireAsync() Acquires a permit only if one is available at the time of invocation.
RFuture<Boolean>	tryAcquireAsync(int permits) Acquires the given number of permits only if all are available at the time of invocation.
RFuture<Boolean>	tryAcquireAsync(int permits, long waitTime, TimeUnit unit) Acquires the given number of permits only if all are available within the given waiting time.
RFuture<Boolean>	tryAcquireAsync(long waitTime, TimeUnit unit) Acquires a permit, if one is available and returns immediately, with the value true, reducing the number of available permits by one.
RFuture<Boolean>	trySetPermitsAsync(int permits) Sets number of permits.

Methods inherited from interface org.redisson.api.RExpirableAsync

clearExpireAsync, expireAsync, expireAtAsync, expireAtAsync, remainTimeToLiveAsync

Methods inherited from interface org.redisson.api.RObjectAsync

addListenerAsync, copyAsync, deleteAsync, dumpAsync, isExistsAsync, migrateAsync, moveAsync, removeListenerAsync, renameAsync, renamenxAsync, restoreAndReplaceAsync, restoreAndReplaceAsync, restoreAsync, restoreAsync, sizeInMemoryAsync, touchAsync, unlinkAsync

Method Detail

tryAcquireAsync

RFuture<Boolean> tryAcquireAsync()

Acquires a permit only if one is available at the time of invocation.

Acquires a permit, if one is available and returns immediately, with the value true, reducing the number of available permits by one.

If no permit is available then this method will return immediately with the value false.

Returns:

true if a permit was acquired and false otherwise

tryAcquireAsync

RFuture<Boolean> tryAcquireAsync(int permits)

Acquires the given number of permits only if all are available at the time of invocation.

Acquires a permits, if all are available and returns immediately, with the value true, reducing the number of available permits by given number of permitss.

If no permits are available then this method will return immediately with the value false.

Parameters:

permits - the number of permits to acquire

Returns:

true if a permit was acquired and false otherwise

acquireAsync

RFuture<Void> acquireAsync()

Acquires a permit from this semaphore.

Acquires a permit, if one is available and returns immediately, reducing the number of available permits by one.

Returns:

void

acquireAsync

RFuture<Void> acquireAsync(int permits)

Acquires the given number of permits, if they are available, and returns immediately, reducing the number of available permits by the given amount.

Parameters:

permits - the number of permits to acquire

Returns:

void

Throws:

IllegalArgumentException - if permits is negative

releaseAsync

RFuture<Void> releaseAsync()

Releases a permit, returning it to the semaphore.

Releases a permit, increasing the number of available permits by one. If any threads of Redisson client are trying to acquire a permit, then one is selected and given the permit that was just released.

There is no requirement that a thread that releases a permit must have acquired that permit by calling acquireAsync(). Correct usage of a semaphore is established by programming convention in the application.

Returns:

void

releaseAsync

RFuture<Void> releaseAsync(int permits)

Releases the given number of permits, returning them to the semaphore.

Releases the given number of permits, increasing the number of available permits by the given number of permits. If any threads of Redisson client are trying to acquire a permits, then next threads is selected and tries to acquire the permits that was just released.

There is no requirement that a thread that releases a permits must have acquired that permit by calling acquireAsync(). Correct usage of a semaphore is established by programming convention in the application.

Parameters:

permits - amount

Returns:

void

trySetPermitsAsync

RFuture<Boolean> trySetPermitsAsync(int permits)

Sets number of permits.

Parameters:

permits - - number of permits

Returns:

true if permits has been set successfully, otherwise false.

tryAcquireAsync

RFuture<Boolean> tryAcquireAsync(long waitTime,
                                 TimeUnit unit)

Acquires a permit, if one is available and returns immediately, with the value true, reducing the number of available permits by one.

If a permit is acquired then the value true is returned.

If the specified waiting time elapses then the value false is returned. If the time is less than or equal to zero, the method will not wait at all.

Parameters:

waitTime - the maximum time to wait for a permit

unit - the time unit of the timeout argument

Returns:

true if a permit was acquired and false if the waiting time elapsed before a permit was acquired

tryAcquireAsync

RFuture<Boolean> tryAcquireAsync(int permits,
                                 long waitTime,
                                 TimeUnit unit)

Acquires the given number of permits only if all are available within the given waiting time.

Acquires a permits, if all are available and returns immediately, with the value true, reducing the number of available permits by one.

If a permits is acquired then the value true is returned.

If the specified waiting time elapses then the value false is returned. If the time is less than or equal to zero, the method will not wait at all.

Parameters:

permits - amount

waitTime - the maximum time to wait for a available permits

unit - the time unit of the timeout argument

Returns:

true if a permit was acquired and false if the waiting time elapsed before a permit was acquired

reducePermitsAsync

RFuture<Void> reducePermitsAsync(int permits)

Shrinks the number of available permits by the indicated reduction. This method can be useful in subclasses that use semaphores to track resources that become unavailable. This method differs from acquireAsync() in that it does not block waiting for permits to become available.

Parameters:

permits - - reduction the number of permits to remove

Returns:

void

Throws:

IllegalArgumentException - if reduction is negative