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: 1.15 $ $Date: 2004/02/28 11:46:33 $

Field Summary
protected  org.apache.commons.pool.PoolableObjectFactory _factory
          My PoolableObjectFactory.
protected  int _maxSleeping
          The cap on the number of "sleeping" instances in the pool.
protected  int _numActive
          Number of object borrowed but not yet returned to the pool
protected  Stack _pool
          My pool.
protected static int DEFAULT_INIT_SLEEPING_CAPACITY
          The default initial size of the pool (this specifies the size of the container, it does not cause the pool to be pre-populated.)
protected static int DEFAULT_MAX_SLEEPING
          The default cap on the number of "sleeping" instances in the pool.
 
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(org.apache.commons.pool.PoolableObjectFactory factory)
          Create a new StackObjectPool using the specified factory to create new instances.
StackObjectPool(org.apache.commons.pool.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(org.apache.commons.pool.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.
 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 invalidateObject(Object obj)
          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.
 void returnObject(Object obj)
          Return an instance to my pool.
 void setFactory(org.apache.commons.pool.PoolableObjectFactory factory)
          Sets the factory I use to create new instances (optional operation).
 
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
 

Field Detail

DEFAULT_MAX_SLEEPING

protected static final int DEFAULT_MAX_SLEEPING
The default cap on the number of "sleeping" instances in the pool.

See Also:
Constant Field Values

DEFAULT_INIT_SLEEPING_CAPACITY

protected static final int DEFAULT_INIT_SLEEPING_CAPACITY
The default initial size of the pool (this specifies the size of the container, it does not cause the pool to be pre-populated.)

See Also:
Constant Field Values

_pool

protected Stack _pool
My pool.


_factory

protected org.apache.commons.pool.PoolableObjectFactory _factory
My PoolableObjectFactory.


_maxSleeping

protected int _maxSleeping
The cap on the number of "sleeping" instances in the pool.


_numActive

protected int _numActive
Number of object borrowed but not yet returned to the pool

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

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

StackObjectPool

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

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.)

StackObjectPool

public StackObjectPool(org.apache.commons.pool.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(org.apache.commons.pool.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(org.apache.commons.pool.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

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

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

invalidateObject

public void invalidateObject(Object obj)
                      throws Exception
Description copied from interface: ObjectPool
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. If the connection should be validated before or after borrowing, then the PoolableObjectFactory.validateObject(java.lang.Object) method should be used instead.

Specified by:
invalidateObject in interface ObjectPool
Specified by:
invalidateObject in class BaseObjectPool
Parameters:
obj - a borrowed instance to be returned.
Exception

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

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

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

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
Exception

setFactory

public void setFactory(org.apache.commons.pool.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


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