Package org.redisson.api

Interface RPermitExpirableSemaphore

All Superinterfaces:

RExpirable, RExpirableAsync, RObject, RObjectAsync, RPermitExpirableSemaphoreAsync

All Known Implementing Classes:

RedissonPermitExpirableSemaphore

public interface RPermitExpirableSemaphore
extends RExpirable, RPermitExpirableSemaphoreAsync

Semaphore object with lease time parameter support 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
String	acquire()	Acquires a permit from this semaphore, blocking until one is available, or the thread is interrupted.
String	acquire(long leaseTime, TimeUnit unit)	Acquires a permit with defined lease time from this semaphore, blocking until one is available, or the thread is interrupted.
void	addPermits(int permits)	Increases or decreases the number of available permits by defined value.
int	availablePermits()	Returns the current number of available permits.
void	release(String permitId)	Releases a permit by its id, returning it to the semaphore.
String	tryAcquire()	Acquires a permit only if one is available at the time of invocation.
String	tryAcquire(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.
String	tryAcquire(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.
boolean	tryRelease(String permitId)	Releases a permit by its id, returning it to the semaphore.
boolean	trySetPermits(int permits)	Sets number of permits.
boolean	updateLeaseTime(String permitId, long leaseTime, TimeUnit unit)	Overrides and updates lease time for defined permit id.

Methods inherited from interface org.redisson.api.RExpirable

clearExpire, expire, expireAt, expireAt, remainTimeToLive

Methods inherited from interface org.redisson.api.RExpirableAsync

clearExpireAsync, expireAsync, expireAtAsync, expireAtAsync, remainTimeToLiveAsync

Methods inherited from interface org.redisson.api.RObject

copy, delete, dump, getCodec, getName, isExists, migrate, move, rename, renamenx, restore, restore, restoreAndReplace, restoreAndReplace, sizeInMemory, touch, unlink

Methods inherited from interface org.redisson.api.RObjectAsync

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

Methods inherited from interface org.redisson.api.RPermitExpirableSemaphoreAsync

acquireAsync, acquireAsync, addPermitsAsync, availablePermitsAsync, releaseAsync, tryAcquireAsync, tryAcquireAsync, tryAcquireAsync, tryReleaseAsync, trySetPermitsAsync, updateLeaseTimeAsync

Method Detail

acquire

String acquire()
        throws InterruptedException

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 release(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.

Returns:

permit id

Throws:

InterruptedException - if the current thread is interrupted

acquire

String acquire(long leaseTime,
               TimeUnit unit)
        throws InterruptedException

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 release(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

Throws:

InterruptedException - if the current thread is interrupted

tryAcquire

String tryAcquire()

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

tryAcquire

String tryAcquire(long waitTime,
                  TimeUnit unit)
           throws InterruptedException

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 release(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; 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

Throws:

InterruptedException - if the current thread is interrupted

tryAcquire

String tryAcquire(long waitTime,
                  long leaseTime,
                  TimeUnit unit)
           throws InterruptedException

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 release(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; 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

Throws:

InterruptedException - if the current thread is interrupted

tryRelease

boolean tryRelease(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 acquire(). 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

release

void release(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 acquire(). 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

availablePermits

int availablePermits()

Returns the current number of available permits.

Returns:

number of available permits

trySetPermits

boolean trySetPermits(int permits)

Sets number of permits.

Parameters:

permits - - number of permits

Returns:

true if permits has been set successfully, otherwise false.

addPermits

void addPermits(int permits)

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

Parameters:

permits - - number of permits to add/remove

updateLeaseTime

boolean updateLeaseTime(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.