org.apache.commons.pool.impl
Class SoftReferenceObjectPool

java.lang.Object
  org.apache.commons.pool.BaseObjectPool
      org.apache.commons.pool.impl.SoftReferenceObjectPool

All Implemented Interfaces:

ObjectPool

public class SoftReferenceObjectPool
extends BaseObjectPool
implements ObjectPool

A SoftReference based ObjectPool.

Since:

Pool 1.0

Version:

$Revision: 777748 $ $Date: 2009-05-22 20:00:44 -0400 (Fri, 22 May 2009) $

Author:

Rodney Waldhoff, Sandy McArthur

Constructor Summary

SoftReferenceObjectPool()
Create a SoftReferenceObjectPool without a factory.

SoftReferenceObjectPool(PoolableObjectFactory factory)
Create a SoftReferenceObjectPool with the specified factory.

SoftReferenceObjectPool(PoolableObjectFactory factory, int initSize)
Deprecated. because this is a SoftReference pool, prefilled idle obejects may be garbage collected before they are used. To be removed in Pool 3.0.

Method Summary

void	addObject() Create an object, and place it into the pool.
Object	borrowObject() Obtains an instance from the pool.
void	clear() Clears any objects sitting idle in the pool.
void	close() Close this pool.
int	getNumActive() Return the number of instances currently borrowed from this pool.
int	getNumIdle() Returns an approximation not less than the of the number of idle instances in the pool.
void	invalidateObject(Object obj) Invalidates an object from the pool.
void	returnObject(Object obj) Returns an instance to the pool.
void	setFactory(PoolableObjectFactory factory) Sets the factory this pool uses to create new instances.

Methods inherited from class org.apache.commons.pool.BaseObjectPool

assertOpen, isClosed

Methods inherited from class java.lang.Object

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

Constructor Detail

SoftReferenceObjectPool

public SoftReferenceObjectPool()

Create a SoftReferenceObjectPool without a factory. setFactory should be called before any attempts to use the pool are made. Generally speaking you should prefer the SoftReferenceObjectPool(PoolableObjectFactory) constructor.

See Also:

SoftReferenceObjectPool(PoolableObjectFactory)

SoftReferenceObjectPool

public SoftReferenceObjectPool(PoolableObjectFactory factory)

Create a SoftReferenceObjectPool with the specified factory.

Parameters:

factory - object factory to use.

SoftReferenceObjectPool

public SoftReferenceObjectPool(PoolableObjectFactory factory,
                               int initSize)
                        throws Exception,
                               IllegalArgumentException

Deprecated. because this is a SoftReference pool, prefilled idle obejects may be garbage collected before they are used. To be removed in Pool 3.0.

Create a SoftReferenceObjectPool with the specified factory and initial idle object count.

Parameters:

factory - object factory to use.

initSize - initial size to attempt to prefill the pool.

Throws:

Exception - when there is a problem prefilling the pool.

IllegalArgumentException - when factory is null.

Method Detail

borrowObject

public Object borrowObject()
                    throws Exception

Description copied from class: BaseObjectPool

Obtains an instance from the pool.

Specified by:

borrowObject in interface ObjectPool

Specified by:

borrowObject in class BaseObjectPool

Returns:

an instance from the pool

Throws:

Exception - if an instance cannot be obtained from the pool

returnObject

public void returnObject(Object obj)
                  throws Exception

Description copied from class: BaseObjectPool

Returns an instance to the pool.

Specified by:

returnObject in interface ObjectPool

Specified by:

returnObject in class BaseObjectPool

Parameters:

obj - instance to return to the pool

Throws:

Exception

invalidateObject

public void invalidateObject(Object obj)
                      throws Exception

Description copied from class: BaseObjectPool

Invalidates an object from the pool. By contract, obj must have been obtained using borrowObject or a related method as defined in an implementation or sub-interface.

This method should be used when an object that has been borrowed is determined (due to an exception or other problem) to be invalid.

Specified by:

invalidateObject in interface ObjectPool

Specified by:

invalidateObject in class BaseObjectPool

Parameters:

obj - a borrowed instance to be disposed.

Throws:

Exception

addObject

public void addObject()
               throws Exception

Create an object, and place it into the pool. addObject() is useful for "pre-loading" a pool with idle objects.

Specified by:

addObject in interface ObjectPool

Overrides:

addObject in class BaseObjectPool

Throws:

Exception - when PoolableObjectFactory.makeObject() fails.

IllegalStateException - after ObjectPool.close() has been called on this pool.

UnsupportedOperationException - when this pool cannot add new idle objects.

getNumIdle

public int getNumIdle()

Returns an approximation not less than the of the number of idle instances in the pool.

Specified by:

getNumIdle in interface ObjectPool

Overrides:

getNumIdle in class BaseObjectPool

Returns:

a negative value.

getNumActive

public int getNumActive()

Return the number of instances currently borrowed from this pool.

Specified by:

getNumActive in interface ObjectPool

Overrides:

getNumActive in class BaseObjectPool

Returns:

the number of instances currently borrowed from this pool

clear

public void clear()

Clears any objects sitting idle in the pool.

Specified by:

clear in interface ObjectPool

Overrides:

clear in class BaseObjectPool

close

public void close()
           throws Exception

Description copied from class: BaseObjectPool

Close this pool. This affects the behavior of isClosed and assertOpen.

Specified by:

close in interface ObjectPool

Overrides:

close in class BaseObjectPool

Throws:

Exception - deprecated: implementations should silently fail if not all resources can be freed.

setFactory

public void setFactory(PoolableObjectFactory factory)
                throws IllegalStateException

Sets the factory this pool uses to create new instances. Trying to change the factory while there are borrowed objects will throw an IllegalStateException.

Specified by:

setFactory in interface ObjectPool

Overrides:

setFactory in class BaseObjectPool

Parameters:

factory - the PoolableObjectFactory used to create new instances.

Throws:

IllegalStateException - when the factory cannot be set at this time