com.hazelcast.concurrent.semaphore

Class SemaphoreProxy

java.lang.Object

com.hazelcast.spi.AbstractDistributedObject<SemaphoreService>

com.hazelcast.concurrent.semaphore.SemaphoreProxy

All Implemented Interfaces:

DistributedObject, ISemaphore

public class SemaphoreProxy
extends AbstractDistributedObject<SemaphoreService>
implements ISemaphore

Field Summary

Fields inherited from class com.hazelcast.spi.AbstractDistributedObject

PARTITIONING_STRATEGY

Constructor Summary

Constructors

Constructor and Description
SemaphoreProxy(String name, SemaphoreService service, NodeEngine nodeEngine)

Method Summary

Methods

Modifier and Type	Method and Description
void	acquire() Acquires a permit if one is available, and returns immediately, reducing the number of available permits by one.
void	acquire(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 permits currently available in this semaphore.
int	drainPermits() Acquires and returns all permits that are immediately available.
String	getName() Returns the name of this ISemaphore instance.
String	getServiceName() Returns the service name for this object.
boolean	init(int permits) Try to initialize this ISemaphore instance with the given permit count
void	reducePermits(int reduction) Shrinks the number of available permits by the indicated reduction.
void	release() Releases a permit, increasing the number of available permits by one.
void	release(int permits) Releases the given number of permits, increasing the number of available permits by that amount.
String	toString()
boolean	tryAcquire() Acquires a permit, if one is available and returns immediately, with the value true, reducing the number of available permits by one.
boolean	tryAcquire(int permits) Acquires the given number of permits, if they are available, and returns immediately, with the value true, reducing the number of available permits by the given amount.
boolean	tryAcquire(int permits, long timeout, TimeUnit unit) Acquires the given number of permits if they are available and returns immediately with the value true, reducing the number of available permits by the given amount.
boolean	tryAcquire(long timeout, 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 com.hazelcast.spi.AbstractDistributedObject

destroy, equals, getNameAsPartitionAwareData, getNodeEngine, getOperationService, getPartitionId, getPartitionKey, getService, hashCode, invalidate, postDestroy, throwNotActiveException

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface com.hazelcast.core.DistributedObject

destroy, getPartitionKey

Constructor Detail

SemaphoreProxy

public SemaphoreProxy(String name,
              SemaphoreService service,
              NodeEngine nodeEngine)

Method Detail

getName

public String getName()

Description copied from interface: ISemaphore

Returns the name of this ISemaphore instance.

Specified by:

getName in interface DistributedObject

Specified by:

getName in interface ISemaphore

Returns:

name of this instance

init

public boolean init(int permits)

Description copied from interface: ISemaphore

Try to initialize this ISemaphore instance with the given permit count

Specified by:

init in interface ISemaphore

Parameters:

permits - the given permit count

Returns:

true if initialization success

acquire

public void acquire()
             throws InterruptedException

Description copied from interface: ISemaphore

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 three things happens:

• some other thread invokes one of the ISemaphore.release() methods for this semaphore and the current thread is next to be assigned a permit,
• this ISemaphore instance is destroyed, or
• some other thread interrupts the current thread.

If the current thread:

• has its interrupted status set on entry to this method; or
• is interrupted while waiting for a permit,

then InterruptedException is thrown and the current thread's interrupted status is cleared.

Specified by:

acquire in interface ISemaphore

Throws:

InterruptedException - if the current thread is interrupted

acquire

public void acquire(int permits)
             throws InterruptedException

Description copied from interface: ISemaphore

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 three 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,
• this ISemaphore instance is destroyed, or
• some other thread interrupts the current thread.

If the current thread:

• has its interrupted status set on entry to this method, or
• is interrupted while waiting for a permit,

then InterruptedException is thrown and the current thread's interrupted status is cleared.

Specified by:

acquire in interface ISemaphore

Parameters:

permits - the number of permits to acquire

Throws:

InterruptedException - if the current thread is interrupted

availablePermits

public int availablePermits()

Description copied from interface: ISemaphore

Returns the current number of permits currently available in this semaphore.

• This method is typically used for debugging and testing purposes.

Specified by:

availablePermits in interface ISemaphore

Returns:

the number of permits available in this semaphore

drainPermits

public int drainPermits()

Description copied from interface: ISemaphore

Acquires and returns all permits that are immediately available.

Specified by:

drainPermits in interface ISemaphore

Returns:

the number of permits drained

reducePermits

public void reducePermits(int reduction)

Description copied from interface: ISemaphore

Shrinks the number of available permits by the indicated reduction. This method differs from acquire in that it does not block waiting for permits to become available.

Specified by:

reducePermits in interface ISemaphore

Parameters:

reduction - the number of permits to remove

release

public void release()

Description copied from interface: ISemaphore

Releases a permit, increasing the number of available permits by one. If any threads in the cluster 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 one of the acquire methods. Correct usage of a semaphore is established by programming convention in the application.

Specified by:

release in interface ISemaphore

release

public void release(int permits)

Description copied from interface: ISemaphore

Releases the given number of permits, increasing the number of available permits by that amount.

There is no requirement that a thread that releases a permit must have acquired that permit by calling one of the acquire methods. Correct usage of a semaphore is established by programming convention in the application.

Specified by:

release in interface ISemaphore

Parameters:

permits - the number of permits to release

tryAcquire

public boolean tryAcquire()

Description copied from interface: ISemaphore

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 ISemaphore

Returns:

true if a permit was acquired and false otherwise

tryAcquire

public boolean tryAcquire(int permits)

Description copied from interface: ISemaphore

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

If insufficient permits are available then this method will return immediately with the value false and the number of available permits is unchanged.

Specified by:

tryAcquire in interface ISemaphore

Parameters:

permits - the number of permits to acquire

Returns:

true if the permits were acquired and false otherwise

tryAcquire

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

Description copied from interface: ISemaphore

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 ISemaphore.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.

If the current thread:

• has its interrupted status set on entry to this method; or
• is interrupted while waiting for a permit,

then InterruptedException is thrown and the current thread's interrupted status is cleared.

Specified by:

tryAcquire in interface ISemaphore

Parameters:

timeout - 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

tryAcquire

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

Description copied from interface: ISemaphore

Acquires the given number of permits if they are available and returns immediately with the value true, 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 three 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, or
• the specified waiting time elapses.

If the permits are acquired then true is returned.

If the specified waiting time elapses then false is returned. If the time is less than or equal to zero, the method will not wait at all.

If the current thread:

• has its interrupted status set on entry to this method, or
• is interrupted while waiting for a permit,

then InterruptedException is thrown and the current thread's interrupted status is cleared.

Specified by:

tryAcquire in interface ISemaphore

Parameters:

permits - the number of permits to acquire

timeout - the maximum time to wait for the permits

unit - the time unit of the timeout argument

Returns:

true if all permits were acquired, false if the waiting time elapsed before all permits could be acquired

Throws:

InterruptedException - if the current thread is interrupted

getServiceName

public String getServiceName()

Description copied from interface: DistributedObject

Returns the service name for this object.

Specified by:

getServiceName in interface DistributedObject

Specified by:

getServiceName in class AbstractDistributedObject<SemaphoreService>

Returns:

the service name for this object.

toString

public String toString()

Overrides:

toString in class AbstractDistributedObject<SemaphoreService>