org.apache.commons.pool.impl
Class StackObjectPool

java.lang.Object
  |
  +--org.apache.commons.pool.BaseObjectPool
        |
        +--org.apache.commons.pool.impl.StackObjectPool

All Implemented Interfaces:

ObjectPool

public class StackObjectPool

extends BaseObjectPool

implements ObjectPool

A simple, Stack-based ObjectPool implementation.

Given a PoolableObjectFactory, this class will maintain a simple pool of instances. A finite number of "sleeping" or idle instances is enforced, but when the pool is empty, new instances are created to support the new load. Hence this class places no limit on the number of "active" instances created by the pool, but is quite useful for re-using Objects without introducing artificial limits.

Version:

$Revision: 1.5 $ $Date: 2002/05/01 06:02:34 $

Author:

Rodney Waldhoff

Constructor Summary

StackObjectPool()
Create a new pool using no factory.

StackObjectPool(int max)
Create a new pool using no factory.

StackObjectPool(int max, int init)
Create a new pool using no factory.

StackObjectPool(PoolableObjectFactory factory)
Create a new StackObjectPool using the specified factory to create new instances.

StackObjectPool(PoolableObjectFactory factory, int max)
Create a new SimpleObjectPool using the specified factory to create new instances, capping the number of "sleeping" instances to max

StackObjectPool(PoolableObjectFactory factory, int max, int init)
Create a new SimpleObjectPool using the specified factory to create new instances, capping the number of "sleeping" instances to max, and initially allocating a container capable of containing at least init instances.

Method Summary

Object	borrowObject() Obtain an instance from my pool.
void	clear() Clears any objects sitting idle in the pool, releasing any associated resources (optional operation).
void	close() Close this pool, and free any resources associated with it.
int	getNumActive() Return the number of instances currently borrowed from my pool (optional operation).
int	getNumIdle() Return the number of instances currently idle in my pool (optional operation).
void	returnObject(Object obj) Return an instance to my pool.
void	setFactory(PoolableObjectFactory factory) Sets the factory I use to create new instances (optional operation).

Methods inherited from class java.lang.Object

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

Constructor Detail

StackObjectPool

public StackObjectPool()

Create a new pool using no factory. Clients must first populate the pool using returnObject(java.lang.Object) before they can be borrowed.

StackObjectPool

public StackObjectPool(int max)

Create a new pool using no factory. Clients must first populate the pool using returnObject(java.lang.Object) before they can be borrowed.

StackObjectPool

public StackObjectPool(int max,
                       int init)

Create a new pool using no factory. Clients must first populate the pool using returnObject(java.lang.Object) before they can be borrowed.

StackObjectPool

public StackObjectPool(PoolableObjectFactory factory)

Create a new StackObjectPool using the specified factory to create new instances.

Parameters:

factory - the PoolableObjectFactory used to populate the pool

StackObjectPool

public StackObjectPool(PoolableObjectFactory factory,
                       int max)

Create a new SimpleObjectPool using the specified factory to create new instances, capping the number of "sleeping" instances to max

Parameters:

factory - the PoolableObjectFactory used to populate the pool

max - cap on the number of "sleeping" instances in the pool

StackObjectPool

public StackObjectPool(PoolableObjectFactory factory,
                       int max,
                       int init)

Create a new SimpleObjectPool using the specified factory to create new instances, capping the number of "sleeping" instances to max, and initially allocating a container capable of containing at least init instances.

Parameters:

factory - the PoolableObjectFactory used to populate the pool

max - cap on the number of "sleeping" instances in the pool

init - initial size of the pool (this specifies the size of the container, it does not cause the pool to be pre-populated.)

Method Detail

borrowObject

public Object borrowObject()
                    throws Exception

Description copied from interface: ObjectPool

Obtain an instance from my pool. By contract, clients MUST return the borrowed instance using returnObject or a related method as defined in an implementation or sub-interface.

The behaviour of this method when the pool has been exhausted is not specified (although it may be specified by implementations).

Specified by:

borrowObject in interface ObjectPool

Specified by:

borrowObject in class BaseObjectPool

Returns:

an instance from my pool.

Exception

clear

public void clear()

Description copied from interface: ObjectPool

Clears any objects sitting idle in the pool, releasing any associated resources (optional operation).

Specified by:

clear in interface ObjectPool

Overrides:

clear in class BaseObjectPool

close

public void close()
           throws Exception

Description copied from interface: ObjectPool

Close this pool, and free any resources associated with it.

Specified by:

close in interface ObjectPool

Overrides:

close in class BaseObjectPool

Exception

getNumActive

public int getNumActive()

Description copied from interface: ObjectPool

Return the number of instances currently borrowed from my pool (optional operation).

Specified by:

getNumActive in interface ObjectPool

Overrides:

getNumActive in class BaseObjectPool

Returns:

the number of instances currently borrowed in my pool

getNumIdle

public int getNumIdle()

Description copied from interface: ObjectPool

Return the number of instances currently idle in my pool (optional operation). This may be considered an approximation of the number of objects that can be borrowed without creating any new instances.

Specified by:

getNumIdle in interface ObjectPool

Overrides:

getNumIdle in class BaseObjectPool

Returns:

the number of instances currently idle in my pool

returnObject

public void returnObject(Object obj)
                  throws Exception

Description copied from interface: ObjectPool

Return an instance to my pool. By contract, obj MUST have been obtained using borrowObject or a related method as defined in an implementation or sub-interface.

Specified by:

returnObject in interface ObjectPool

Specified by:

returnObject in class BaseObjectPool

Parameters:

obj - a borrowed instance to be returned.

Exception

setFactory

public void setFactory(PoolableObjectFactory factory)
                throws IllegalStateException

Description copied from interface: ObjectPool

Sets the factory I use to create new instances (optional operation).

Specified by:

setFactory in interface ObjectPool

Overrides:

setFactory in class BaseObjectPool

Parameters:

factory - the PoolableObjectFactory I use to create new instances.

Throws:

IllegalStateException - when the factory cannot be set at this time