Package org.redisson.api

Interface RPermitExpirableSemaphoreAsync

All Superinterfaces:

RExpirableAsync, RObjectAsync

All Known Subinterfaces:

RPermitExpirableSemaphore

All Known Implementing Classes:

RedissonPermitExpirableSemaphore

public interface RPermitExpirableSemaphoreAsync
extends RExpirableAsync

Semaphore object with support of lease time parameter for each acquired permit.

Each permit identified by own id and could be released only using its id. Permit id is a 128-bits unique random identifier generated each time during acquiring.

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

Author:

Nikita Koksharov

Method Summary

Modifier and Type	Method	Description
RFuture<String>	acquireAsync()	Acquires a permit from this semaphore, blocking until one is available, or the thread is interrupted.
RFuture<String>	acquireAsync(long leaseTime, TimeUnit unit)	Acquires a permit with defined lease time from this semaphore, blocking until one is available, or the thread is interrupted.
RFuture<Void>	addPermitsAsync(int permits)	Increases or decreases the number of available permits by defined value.
RFuture<Integer>	availablePermitsAsync()	Returns the current number of available permits.
RFuture<Void>	releaseAsync(String permitId)	Releases a permit by its id, returning it to the semaphore.
RFuture<String>	tryAcquireAsync()	Acquires a permit only if one is available at the time of invocation.
RFuture<String>	tryAcquireAsync(long waitTime, long leaseTime, TimeUnit unit)	Acquires a permit with defined lease time from this semaphore, if one becomes available within the given waiting time and the current thread has not been interrupted.
RFuture<String>	tryAcquireAsync(long waitTime, TimeUnit unit)	Acquires a permit from this semaphore, if one becomes available within the given waiting time and the current thread has not been interrupted.
RFuture<Boolean>	tryReleaseAsync(String permitId)	Releases a permit by its id, returning it to the semaphore.
RFuture<Boolean>	trySetPermitsAsync(int permits)	Sets number of permits.
RFuture<Boolean>	updateLeaseTimeAsync(String permitId, long leaseTime, TimeUnit unit)	Overrides and updates lease time for defined permit id.

Methods inherited from interface org.redisson.api.RExpirableAsync

clearExpireAsync, expireAsync, expireAtAsync, expireAtAsync, remainTimeToLiveAsync

Methods inherited from interface org.redisson.api.RObjectAsync

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

Method Detail

acquireAsync

RFuture<String> acquireAsync()

Acquires a permit from this semaphore, blocking until one is available, or the thread is interrupted.

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

If no permit is available then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of two things happens:

• Some other thread invokes the releaseAsync(String) method for this semaphore and the current thread is next to be assigned a permit; or
• Some other thread interrupts the current thread.

Returns:

permit id

acquireAsync

RFuture<String> acquireAsync(long leaseTime,
                             TimeUnit unit)

Acquires a permit with defined lease time from this semaphore, blocking until one is available, or the thread is interrupted.

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

If no permit is available then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of two things happens:

• Some other thread invokes the releaseAsync(java.lang.String) method for this semaphore and the current thread is next to be assigned a permit; or
• Some other thread interrupts the current thread.

Parameters:

leaseTime - - permit lease time

unit - - time unit

Returns:

permit id

tryAcquireAsync

RFuture<String> 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 permit id, reducing the number of available permits by one.

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

Returns:

permit id if a permit was acquired and null otherwise

tryAcquireAsync

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

Acquires a permit from this semaphore, if one becomes available within the given waiting time and the current thread has not been interrupted.

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

If no permit is available then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of three things happens:

• Some other thread invokes the releaseAsync(String) method for this semaphore and the current thread is next to be assigned a permit; or
• Some other thread interrupts the current thread; or
• The specified waiting time elapses.

If a permit is acquired then the permit id is returned.

If the specified waiting time elapses then the value null 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:

permit id if a permit was acquired and null if the waiting time elapsed before a permit was acquired

tryAcquireAsync

RFuture<String> tryAcquireAsync(long waitTime,
                                long leaseTime,
                                TimeUnit unit)

Acquires a permit with defined lease time from this semaphore, if one becomes available within the given waiting time and the current thread has not been interrupted.

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

If no permit is available then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of three things happens:

• Some other thread invokes the releaseAsync(String) method for this semaphore and the current thread is next to be assigned a permit; or
• Some other thread interrupts the current thread; or
• The specified waiting time elapses.

If a permit is acquired then the permit id is returned.

If the specified waiting time elapses then the value null 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

leaseTime - permit lease time, use -1 to make it permanent

unit - the time unit of the timeout argument

Returns:

permit id if a permit was acquired and null if the waiting time elapsed before a permit was acquired

tryReleaseAsync

RFuture<Boolean> tryReleaseAsync(String permitId)

Releases a permit by its id, 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.

Parameters:

permitId - - permit id

Returns:

true if a permit has been released and false otherwise

releaseAsync

RFuture<Void> releaseAsync(String permitId)

Releases a permit by its id, 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.

Throws an exception if permit id doesn't exist or has already been release

Parameters:

permitId - - permit id

Returns:

void

availablePermitsAsync

RFuture<Integer> availablePermitsAsync()

Returns the current number of available permits.

Returns:

number of available permits

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.

addPermitsAsync

RFuture<Void> addPermitsAsync(int permits)

Increases or decreases the number of available permits by defined value.

Parameters:

permits - - number of permits to add/remove

Returns:

void

updateLeaseTimeAsync

RFuture<Boolean> updateLeaseTimeAsync(String permitId,
                                      long leaseTime,
                                      TimeUnit unit)

Overrides and updates lease time for defined permit id.

Parameters:

permitId - - permit id

leaseTime - - permit lease time, use -1 to make it permanent

unit - - the time unit of the timeout argument

Returns:

true if permits has been updated successfully, otherwise false.