org.apache.commons.pool.impl
Class StackObjectPool

java.lang.Object
  extended by org.apache.commons.pool.BaseObjectPool
      extended by 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.

Since:
Pool 1.0
Version:
$Revision: 777748 $ $Date: 2009-05-22 20:00:44 -0400 (Fri, 22 May 2009) $
Author:
Rodney Waldhoff, Dirk Verbeeck, Sandy McArthur

Constructor Summary
StackObjectPool()
          Create a new pool using no factory.
StackObjectPool(int maxIdle)
          Create a new pool using no factory.
StackObjectPool(int maxIdle, int initIdleCapacity)
          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 maxIdle)
          Create a new SimpleObjectPool using the specified factory to create new instances, capping the number of "sleeping" instances to max.
StackObjectPool(PoolableObjectFactory factory, int maxIdle, int initIdleCapacity)
          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
 void addObject()
          Create an object, and place it into the pool.
 java.lang.Object borrowObject()
          Obtains an instance from the pool.
 void clear()
          Clears any objects sitting idle in the pool.
 void close()
          Close this pool, and free any resources associated with it.
 int getNumActive()
          Return the number of instances currently borrowed from this pool.
 int getNumIdle()
          Return the number of instances currently idle in this pool.
 void invalidateObject(java.lang.Object obj)
          Invalidates an object from the pool.
 void returnObject(java.lang.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 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 set the factory else this pool will not behave correctly. Clients may first populate the pool using returnObject(java.lang.Object) before they can be borrowed but this useage is discouraged.

See Also:
StackObjectPool(PoolableObjectFactory)

StackObjectPool

public StackObjectPool(int maxIdle)
Create a new pool using no factory. Clients must first set the factory else this pool will not behave correctly. Clients may first populate the pool using returnObject(java.lang.Object) before they can be borrowed but this useage is discouraged.

Parameters:
maxIdle - cap on the number of "sleeping" instances in the pool
See Also:
StackObjectPool(PoolableObjectFactory, int)

StackObjectPool

public StackObjectPool(int maxIdle,
                       int initIdleCapacity)
Create a new pool using no factory. Clients must first set the factory else this pool will not behave correctly. Clients may first populate the pool using returnObject(java.lang.Object) before they can be borrowed but this useage is discouraged.

Parameters:
maxIdle - cap on the number of "sleeping" instances in the pool
initIdleCapacity - initial size of the pool (this specifies the size of the container, it does not cause the pool to be pre-populated.)
See Also:
StackObjectPool(PoolableObjectFactory, int, int)

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 maxIdle)
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
maxIdle - cap on the number of "sleeping" instances in the pool

StackObjectPool

public StackObjectPool(PoolableObjectFactory factory,
                       int maxIdle,
                       int initIdleCapacity)
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
maxIdle - cap on the number of "sleeping" instances in the pool
initIdleCapacity - initial size of the pool (this specifies the size of the container, it does not cause the pool to be pre-populated.)
Method Detail

addObject

public void addObject()
               throws java.lang.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:
java.lang.Exception - when the _factory has a problem creating an object.

borrowObject

public java.lang.Object borrowObject()
                              throws java.lang.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:
java.lang.Exception - if an instance cannot be obtained from the 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 java.lang.Exception
Close this pool, and free any resources associated with it.

Calling addObject() or borrowObject() after invoking this method on a pool will cause them to throw an IllegalStateException.

Specified by:
close in interface ObjectPool
Overrides:
close in class BaseObjectPool
Throws:
java.lang.Exception - deprecated: implementations should silently fail if not all resources can be freed.

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

getNumIdle

public int getNumIdle()
Return the number of instances currently idle in this pool.

Specified by:
getNumIdle in interface ObjectPool
Overrides:
getNumIdle in class BaseObjectPool
Returns:
the number of instances currently idle in this pool

invalidateObject

public void invalidateObject(java.lang.Object obj)
                      throws java.lang.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:
java.lang.Exception

returnObject

public void returnObject(java.lang.Object obj)
                  throws java.lang.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:
java.lang.Exception

setFactory

public void setFactory(PoolableObjectFactory factory)
                throws java.lang.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:
java.lang.IllegalStateException - when the factory cannot be set at this time


Copyright © 2001-2003 Apache Software Foundation. Documenation generated November 9 2009.