Package org.redisson

Class RedissonSemaphore

java.lang.Object

org.redisson.RedissonObject

org.redisson.RedissonSemaphore

All Implemented Interfaces:

RExpirable, RExpirableAsync, RObject, RObjectAsync, RSemaphore, RSemaphoreAsync

Direct Known Subclasses:

RedissonQueueSemaphore

public class RedissonSemaphore
extends RedissonObject
implements RSemaphore

Distributed and concurrent implementation of Semaphore.

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

Author:

Nikita Koksharov

Field Summary

Fields inherited from class org.redisson.RedissonObject

codec

Constructor Summary

Constructors

Constructor	Description
RedissonSemaphore(CommandAsyncExecutor commandExecutor, String name, SemaphorePubSub semaphorePubSub)

Method Summary

Modifier and Type	Method	Description
void	acquire()	Acquires a permit from this semaphore, blocking until one is available, or the thread is interrupted.
void	acquire(int permits)	Acquires the given number of permits from this semaphore, blocking until all are available, or the thread is interrupted.
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.
int	availablePermits()	Returns the current number of available permits.
boolean	clearExpire()	Clear an expire timeout or expire date for object.
RFuture<Boolean>	clearExpireAsync()	Clear an expire timeout or expire date for object in async mode.
int	drainPermits()	Acquires and returns all permits that are immediately available.
boolean	expire(long timeToLive, TimeUnit timeUnit)	Set a timeout for object.
RFuture<Boolean>	expireAsync(long timeToLive, TimeUnit timeUnit)	Set a timeout for object in async mode.
boolean	expireAt(long timestamp)	Set an expire date for object.
boolean	expireAt(Date timestamp)	Set an expire date for object.
RFuture<Boolean>	expireAtAsync(long timestamp)	Set an expire date for object in async mode.
RFuture<Boolean>	expireAtAsync(Date timestamp)	Set an expire date for object in async mode.
static String	getChannelName(String name)
void	reducePermits(int permits)	Shrinks the number of available permits by the indicated reduction.
RFuture<Void>	reducePermitsAsync(int permits)	Shrinks the number of available permits by the indicated reduction.
void	release()	Releases a permit, returning it to the semaphore.
void	release(int permits)	Releases the given number of permits, returning them to the semaphore.
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.
long	remainTimeToLive()	Remaining time to live of Redisson object that has a timeout
RFuture<Long>	remainTimeToLiveAsync()	Remaining time to live of Redisson object that has a timeout
boolean	tryAcquire()	Acquires a permit only if one is available at the time of invocation.
boolean	tryAcquire(int permits)	Acquires the given number of permits only if all are available at the time of invocation.
boolean	tryAcquire(int permits, long waitTime, TimeUnit unit)	Acquires the given number of permits only if all are available within the given waiting time and the current thread has not been interrupted.
boolean	tryAcquire(long time, 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>	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.
boolean	trySetPermits(int permits)	Sets number of permits.
RFuture<Boolean>	trySetPermitsAsync(int permits)	Sets number of permits.

Methods inherited from class org.redisson.RedissonObject

await, copy, copyAsync, delete, deleteAsync, dump, dumpAsync, encode, encode, encode, encodeMapKey, encodeMapKeys, encodeMapValue, encodeMapValues, get, getCodec, getName, getName, isExists, isExistsAsync, migrate, migrateAsync, move, moveAsync, prefixName, rename, renameAsync, renamenx, renamenxAsync, restore, restore, restoreAndReplace, restoreAndReplace, restoreAndReplaceAsync, restoreAndReplaceAsync, restoreAsync, restoreAsync, suffixName, toSeconds, touch, touchAsync, unlink, unlinkAsync

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

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, touch, unlink

Methods inherited from interface org.redisson.api.RObjectAsync

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

Constructor Detail

RedissonSemaphore

public RedissonSemaphore(CommandAsyncExecutor commandExecutor,
                         String name,
                         SemaphorePubSub semaphorePubSub)

Method Detail

getChannelName

public static String getChannelName(String name)

acquire

public void acquire()
             throws InterruptedException

Description copied from interface: RSemaphore

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 immediately, 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 RSemaphore.release() method for this semaphore and the current thread is next to be assigned a permit; or
• Some other thread interrupts the current thread.

Specified by:

acquire in interface RSemaphore

Throws:

InterruptedException - if the current thread is interrupted

acquire

public void acquire(int permits)
             throws InterruptedException

Description copied from interface: RSemaphore

Acquires the given number of permits from this semaphore, blocking until all are available, or the thread is interrupted.

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

If insufficient permits are available then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of two things happens:

• Some other thread invokes one of the release methods for this semaphore, the current thread is next to be assigned permits and the number of available permits satisfies this request; or
• Some other thread interrupts the current thread.

Specified by:

acquire in interface RSemaphore

Parameters:

permits - the number of permits to acquire

Throws:

InterruptedException - if the current thread is interrupted

acquireAsync

public RFuture<Void> acquireAsync()

Description copied from interface: RSemaphoreAsync

Acquires a permit from this semaphore.

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

Specified by:

acquireAsync in interface RSemaphoreAsync

Returns:

void

acquireAsync

public RFuture<Void> acquireAsync(int permits)

Description copied from interface: RSemaphoreAsync

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

Specified by:

acquireAsync in interface RSemaphoreAsync

Parameters:

permits - the number of permits to acquire

Returns:

void

tryAcquire

public boolean tryAcquire()

Description copied from interface: RSemaphore

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.

Specified by:

tryAcquire in interface RSemaphore

Returns:

true if a permit was acquired and false otherwise

tryAcquire

public boolean tryAcquire(int permits)

Description copied from interface: RSemaphore

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 permits.

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

Specified by:

tryAcquire in interface RSemaphore

Parameters:

permits - the number of permits to acquire

Returns:

true if a permit was acquired and false otherwise

tryAcquireAsync

public RFuture<Boolean> tryAcquireAsync()

Description copied from interface: RSemaphoreAsync

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.

Specified by:

tryAcquireAsync in interface RSemaphoreAsync

Returns:

true if a permit was acquired and false otherwise

tryAcquireAsync

public RFuture<Boolean> tryAcquireAsync(int permits)

Description copied from interface: RSemaphoreAsync

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.

Specified by:

tryAcquireAsync in interface RSemaphoreAsync

Parameters:

permits - the number of permits to acquire

Returns:

true if a permit was acquired and false otherwise

tryAcquireAsync

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

Description copied from interface: RSemaphoreAsync

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.

Specified by:

tryAcquireAsync in interface RSemaphoreAsync

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

tryAcquire

public boolean tryAcquire(int permits,
                          long waitTime,
                          TimeUnit unit)
                   throws InterruptedException

Description copied from interface: RSemaphore

Acquires the given number of permits only if all are available within the given waiting time and the current thread has not been interrupted.

Acquires a permits, if all are available and returns immediately, with the value true, 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 RSemaphore.release() 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 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.

Specified by:

tryAcquire in interface RSemaphore

Parameters:

permits - amount

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

Throws:

InterruptedException - if the current thread is interrupted

tryAcquireAsync

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

Description copied from interface: RSemaphoreAsync

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.

Specified by:

tryAcquireAsync in interface RSemaphoreAsync

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

tryAcquire

public boolean tryAcquire(long time,
                          TimeUnit unit)
                   throws InterruptedException

Description copied from interface: RSemaphore

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 value true, 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 RSemaphore.release() 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 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.

Specified by:

tryAcquire in interface RSemaphore

Parameters:

time - 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

Throws:

InterruptedException - if the current thread is interrupted

release

public void release()

Description copied from interface: RSemaphore

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 RSemaphore.acquire(). Correct usage of a semaphore is established by programming convention in the application.

Specified by:

release in interface RSemaphore

release

public void release(int permits)

Description copied from interface: RSemaphore

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 RSemaphore.acquire(). Correct usage of a semaphore is established by programming convention in the application.

Specified by:

release in interface RSemaphore

Parameters:

permits - amount

releaseAsync

public RFuture<Void> releaseAsync()

Description copied from interface: RSemaphoreAsync

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 RSemaphoreAsync.acquireAsync(). Correct usage of a semaphore is established by programming convention in the application.

Specified by:

releaseAsync in interface RSemaphoreAsync

Returns:

void

releaseAsync

public RFuture<Void> releaseAsync(int permits)

Description copied from interface: RSemaphoreAsync

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 RSemaphoreAsync.acquireAsync(). Correct usage of a semaphore is established by programming convention in the application.

Specified by:

releaseAsync in interface RSemaphoreAsync

Parameters:

permits - amount

Returns:

void

drainPermits

public int drainPermits()

Description copied from interface: RSemaphore

Acquires and returns all permits that are immediately available.

Specified by:

drainPermits in interface RSemaphore

Returns:

the number of permits acquired

availablePermits

public int availablePermits()

Description copied from interface: RSemaphore

Returns the current number of available permits.

Specified by:

availablePermits in interface RSemaphore

Returns:

number of available permits

trySetPermits

public boolean trySetPermits(int permits)

Description copied from interface: RSemaphore

Sets number of permits.

Specified by:

trySetPermits in interface RSemaphore

Parameters:

permits - - number of permits

Returns:

true if permits has been set successfully, otherwise false.

trySetPermitsAsync

public RFuture<Boolean> trySetPermitsAsync(int permits)

Description copied from interface: RSemaphoreAsync

Sets number of permits.

Specified by:

trySetPermitsAsync in interface RSemaphoreAsync

Parameters:

permits - - number of permits

Returns:

true if permits has been set successfully, otherwise false.

reducePermits

public void reducePermits(int permits)

Description copied from interface: RSemaphore

Shrinks the number of available permits by the indicated reduction.

Specified by:

reducePermits in interface RSemaphore

Parameters:

permits - - reduction the number of permits to remove

reducePermitsAsync

public RFuture<Void> reducePermitsAsync(int permits)

Description copied from interface: RSemaphoreAsync

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 RSemaphoreAsync.acquireAsync() in that it does not block waiting for permits to become available.

Specified by:

reducePermitsAsync in interface RSemaphoreAsync

Parameters:

permits - - reduction the number of permits to remove

Returns:

void

expire

public boolean expire(long timeToLive,
                      TimeUnit timeUnit)

Description copied from interface: RExpirable

Set a timeout for object. After the timeout has expired, the key will automatically be deleted.

Specified by:

expire in interface RExpirable

Parameters:

timeToLive - - timeout before object will be deleted

timeUnit - - timeout time unit

Returns:

true if the timeout was set and false if not

expireAsync

public RFuture<Boolean> expireAsync(long timeToLive,
                                    TimeUnit timeUnit)

Description copied from interface: RExpirableAsync

Set a timeout for object in async mode. After the timeout has expired, the key will automatically be deleted.

Specified by:

expireAsync in interface RExpirableAsync

Parameters:

timeToLive - - timeout before object will be deleted

timeUnit - - timeout time unit

Returns:

true if the timeout was set and false if not

expireAt

public boolean expireAt(long timestamp)

Description copied from interface: RExpirable

Set an expire date for object. When expire date comes the key will automatically be deleted.

Specified by:

expireAt in interface RExpirable

Parameters:

timestamp - - expire date in milliseconds (Unix timestamp)

Returns:

true if the timeout was set and false if not

expireAtAsync

public RFuture<Boolean> expireAtAsync(long timestamp)

Description copied from interface: RExpirableAsync

Set an expire date for object in async mode. When expire date comes the key will automatically be deleted.

Specified by:

expireAtAsync in interface RExpirableAsync

Parameters:

timestamp - - expire date in milliseconds (Unix timestamp)

Returns:

true if the timeout was set and false if not

expireAt

public boolean expireAt(Date timestamp)

Description copied from interface: RExpirable

Set an expire date for object. When expire date comes the key will automatically be deleted.

Specified by:

expireAt in interface RExpirable

Parameters:

timestamp - - expire date

Returns:

true if the timeout was set and false if not

expireAtAsync

public RFuture<Boolean> expireAtAsync(Date timestamp)

Description copied from interface: RExpirableAsync

Set an expire date for object in async mode. When expire date comes the key will automatically be deleted.

Specified by:

expireAtAsync in interface RExpirableAsync

Parameters:

timestamp - - expire date

Returns:

true if the timeout was set and false if not

clearExpire

public boolean clearExpire()

Description copied from interface: RExpirable

Clear an expire timeout or expire date for object.

Specified by:

clearExpire in interface RExpirable

Returns:

true if timeout was removed false if object does not exist or does not have an associated timeout

clearExpireAsync

public RFuture<Boolean> clearExpireAsync()

Description copied from interface: RExpirableAsync

Clear an expire timeout or expire date for object in async mode. Object will not be deleted.

Specified by:

clearExpireAsync in interface RExpirableAsync

Returns:

true if the timeout was cleared and false if not

remainTimeToLive

public long remainTimeToLive()

Description copied from interface: RExpirable

Remaining time to live of Redisson object that has a timeout

Specified by:

remainTimeToLive in interface RExpirable

Returns:

time in milliseconds -2 if the key does not exist. -1 if the key exists but has no associated expire.

remainTimeToLiveAsync

public RFuture<Long> remainTimeToLiveAsync()

Description copied from interface: RExpirableAsync

Remaining time to live of Redisson object that has a timeout

Specified by:

remainTimeToLiveAsync in interface RExpirableAsync

Returns:

time in milliseconds -2 if the key does not exist. -1 if the key exists but has no associated expire.