org.redisson.api.RSemaphoreAsync Maven / Gradle / Ivy
/**
* Copyright (c) 2013-2019 Nikita Koksharov
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.redisson.api;
import java.util.concurrent.TimeUnit;
/**
* Distributed and concurrent implementation of {@link java.util.concurrent.Semaphore}.
*
* Works in non-fair mode. Therefore order of acquiring is unpredictable.
*
* @author Nikita Koksharov
*
*/
public interface RSemaphoreAsync extends RExpirableAsync {
/**
* 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 {@code true},
* reducing the number of available permits by one.
*
*
If no permit is available then this method will return
* immediately with the value {@code false}.
*
* @return {@code true} if a permit was acquired and {@code false}
* otherwise
*/
RFuture tryAcquireAsync();
/**
* 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 {@code 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 {@code false}.
*
* @param permits the number of permits to acquire
* @return {@code true} if a permit was acquired and {@code false}
* otherwise
*/
RFuture tryAcquireAsync(int permits);
/**
* Acquires a permit from this semaphore.
*
* Acquires a permit, if one is available and returns immediately,
* reducing the number of available permits by one.
*
* @return void
*
*/
RFuture acquireAsync();
/**
* Acquires the given number of permits, if they are available,
* and returns immediately, reducing the number of available permits
* by the given amount.
*
* @param permits the number of permits to acquire
* @throws IllegalArgumentException if {@code permits} is negative
* @return void
*/
RFuture acquireAsync(int permits);
/**
* 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 {@link #acquireAsync()}.
* Correct usage of a semaphore is established by programming convention
* in the application.
*
* @return void
*/
RFuture releaseAsync();
/**
* 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 {@link #acquireAsync()}.
* Correct usage of a semaphore is established by programming convention
* in the application.
*
* @param permits amount
* @return void
*/
RFuture releaseAsync(int permits);
/**
* Sets number of permits.
*
* @param permits - number of permits
* @return true if permits has been set successfully, otherwise false.
*/
RFuture trySetPermitsAsync(int permits);
/**
* Acquires a permit, if one is available and returns immediately,
* with the value {@code true},
* reducing the number of available permits by one.
*
*
If a permit is acquired then the value {@code true} is returned.
*
*
If the specified waiting time elapses then the value {@code false}
* is returned. If the time is less than or equal to zero, the method
* will not wait at all.
*
* @param waitTime the maximum time to wait for a permit
* @param unit the time unit of the {@code timeout} argument
* @return {@code true} if a permit was acquired and {@code false}
* if the waiting time elapsed before a permit was acquired
*/
RFuture tryAcquireAsync(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 {@code true},
* reducing the number of available permits by one.
*
*
If a permits is acquired then the value {@code true} is returned.
*
*
If the specified waiting time elapses then the value {@code false}
* is returned. If the time is less than or equal to zero, the method
* will not wait at all.
*
* @param permits amount
* @param waitTime the maximum time to wait for a available permits
* @param unit the time unit of the {@code timeout} argument
* @return {@code true} if a permit was acquired and {@code false}
* if the waiting time elapsed before a permit was acquired
*/
RFuture tryAcquireAsync(int permits, long waitTime, TimeUnit unit);
/**
* 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 {@link #acquireAsync()} in that it does not block
* waiting for permits to become available.
*
* @param permits - reduction the number of permits to remove
* @return void
* @throws IllegalArgumentException if {@code reduction} is negative
*/
RFuture reducePermitsAsync(int permits);
}