org.redisson

Class RedissonSemaphore

java.lang.Object

org.redisson.RedissonSemaphore

All Implemented Interfaces:

RExpirable, RExpirableAsync, RObject, RObjectAsync, RSemaphore

public class RedissonSemaphore
extends Object
implements RSemaphore

Distributed and concurrent implementation of Semaphore.

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

Author:

Nikita Koksharov

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	RedissonSemaphore(CommandExecutor commandExecutor, String name, UUID id)

Method Summary

Methods

Modifier and Type	Method and 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.
int	availablePermits() Returns the current number of available permits.
boolean	clearExpire() Clear an expire timeout or expire date for object.
io.netty.util.concurrent.Future<Boolean>	clearExpireAsync() Clear an expire timeout or expire date for object in async mode.
boolean	delete() Deletes the object
io.netty.util.concurrent.Future<Boolean>	deleteAsync() Delete 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.
io.netty.util.concurrent.Future<Boolean>	expireAsync(long timeToLive, TimeUnit timeUnit) Set a timeout for object in async mode.
boolean	expireAt(Date timestamp) Set an expire date for object.
boolean	expireAt(long timestamp) Set an expire date for object.
io.netty.util.concurrent.Future<Boolean>	expireAtAsync(Date timestamp) Set an expire date for object in async mode.
io.netty.util.concurrent.Future<Boolean>	expireAtAsync(long timestamp) Set an expire date for object in async mode.
protected <V> V	get(io.netty.util.concurrent.Future<V> future)
String	getName() Returns name of object
boolean	isExists() Check object existence
io.netty.util.concurrent.Future<Boolean>	isExistsAsync() Check object existence in async mode.
void	migrate(String host, int port, int database) Transfer an object from source Redis instance to destination Redis instance
io.netty.util.concurrent.Future<Void>	migrateAsync(String host, int port, int database) Transfer an object from source Redis instance to destination Redis instance in async mode
boolean	move(int database) Move object to another database
io.netty.util.concurrent.Future<Boolean>	moveAsync(int database) Move object to another database in async mode
protected <V> io.netty.util.concurrent.Promise<V>	newPromise()
protected <V> io.netty.util.concurrent.Future<V>	newSucceededFuture(V result)
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.
long	remainTimeToLive() Remaining time to live of Redisson object that has a timeout
io.netty.util.concurrent.Future<Long>	remainTimeToLiveAsync() Get remaining time to live of object in seconds.
void	rename(String newName) Rename current object key to newName
io.netty.util.concurrent.Future<Void>	renameAsync(String newName) Rename current object key to newName in async mode
boolean	renamenx(String newName) Rename current object key to newName only if new key is not exists
io.netty.util.concurrent.Future<Boolean>	renamenxAsync(String newName) Rename current object key to newName in async mode only if new key is not exists
void	setPermits(int permits) Sets new number of permits.
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)
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.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.redisson.core.RExpirable

clearExpire, expire, expireAt, expireAt, remainTimeToLive

Methods inherited from interface org.redisson.core.RObject

delete, getName, isExists, migrate, move, rename, renamenx

Methods inherited from interface org.redisson.core.RExpirableAsync

clearExpireAsync, expireAsync, expireAtAsync, expireAtAsync, remainTimeToLiveAsync

Methods inherited from interface org.redisson.core.RObjectAsync

deleteAsync, isExistsAsync, migrateAsync, moveAsync, renameAsync, renamenxAsync

Constructor Detail

RedissonSemaphore

protected RedissonSemaphore(CommandExecutor commandExecutor,
                 String name,
                 UUID id)

Method Detail

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

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 permitss.

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

tryAcquire

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

Specified by:

tryAcquire in interface RSemaphore

Throws:

InterruptedException

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

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

setPermits

public void setPermits(int permits)

Description copied from interface: RSemaphore

Sets new number of permits.

Specified by:

setPermits in interface RSemaphore

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 io.netty.util.concurrent.Future<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 io.netty.util.concurrent.Future<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 seconds (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 io.netty.util.concurrent.Future<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 io.netty.util.concurrent.Future<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 io.netty.util.concurrent.Future<Long> remainTimeToLiveAsync()

Description copied from interface: RExpirableAsync

Get remaining time to live of object in seconds.

Specified by:

remainTimeToLiveAsync in interface RExpirableAsync

Returns:

-1 if object does not exist or time in seconds

get

protected <V> V get(io.netty.util.concurrent.Future<V> future)

newPromise

protected <V> io.netty.util.concurrent.Promise<V> newPromise()

newSucceededFuture

protected <V> io.netty.util.concurrent.Future<V> newSucceededFuture(V result)

getName

public String getName()

Description copied from interface: RObject

Returns name of object

Specified by:

getName in interface RObject

Returns:

name

rename

public void rename(String newName)

Description copied from interface: RObject

Rename current object key to newName

Specified by:

rename in interface RObject

renameAsync

public io.netty.util.concurrent.Future<Void> renameAsync(String newName)

Description copied from interface: RObjectAsync

Rename current object key to newName in async mode

Specified by:

renameAsync in interface RObjectAsync

Returns:

migrate

public void migrate(String host,
           int port,
           int database)

Description copied from interface: RObject

Transfer an object from source Redis instance to destination Redis instance

Specified by:

migrate in interface RObject

Parameters:

host - - destination host

port - - destination port

database - - destination database

migrateAsync

public io.netty.util.concurrent.Future<Void> migrateAsync(String host,
                                                 int port,
                                                 int database)

Description copied from interface: RObjectAsync

Transfer an object from source Redis instance to destination Redis instance in async mode

Specified by:

migrateAsync in interface RObjectAsync

Parameters:

host - - destination host

port - - destination port

database - - destination database

Returns:

move

public boolean move(int database)

Description copied from interface: RObject

Move object to another database

Specified by:

move in interface RObject

Returns:

true if key was moved else false

moveAsync

public io.netty.util.concurrent.Future<Boolean> moveAsync(int database)

Description copied from interface: RObjectAsync

Move object to another database in async mode

Specified by:

moveAsync in interface RObjectAsync

Returns:

true if key was moved false if not

renamenx

public boolean renamenx(String newName)

Description copied from interface: RObject

Rename current object key to newName only if new key is not exists

Specified by:

renamenx in interface RObject

Returns:

renamenxAsync

public io.netty.util.concurrent.Future<Boolean> renamenxAsync(String newName)

Description copied from interface: RObjectAsync

Rename current object key to newName in async mode only if new key is not exists

Specified by:

renamenxAsync in interface RObjectAsync

Returns:

delete

public boolean delete()

Description copied from interface: RObject

Deletes the object

Specified by:

delete in interface RObject

deleteAsync

public io.netty.util.concurrent.Future<Boolean> deleteAsync()

Description copied from interface: RObjectAsync

Delete object in async mode

Specified by:

deleteAsync in interface RObjectAsync

Returns:

true if object was deleted false if not

isExists

public boolean isExists()

Description copied from interface: RObject

Check object existence

Specified by:

isExists in interface RObject

Returns:

true if object exists and false otherwise

isExistsAsync

public io.netty.util.concurrent.Future<Boolean> isExistsAsync()

Description copied from interface: RObjectAsync

Check object existence in async mode.

Specified by:

isExistsAsync in interface RObjectAsync

Returns:

true if object exists and false otherwise