org.apache.commons.pool2

Class PoolUtils.ErodingObjectPool<T>

java.lang.Object

org.apache.commons.pool2.PoolUtils.ErodingObjectPool<T>

All Implemented Interfaces:

ObjectPool<T>

Enclosing class:

PoolUtils

private static class PoolUtils.ErodingObjectPool<T>
extends java.lang.Object
implements ObjectPool<T>

Decorates an object pool, adding "eroding" behavior. Based on the configured erosion factor, objects returning to the pool may be invalidated instead of being added to idle capacity.

Field Summary

Fields

Modifier and Type	Field and Description
private PoolUtils.ErodingFactor	factor Erosion factor
private ObjectPool<T>	pool Underlying object pool

Constructor Summary

Constructors

Constructor and Description
ErodingObjectPool(ObjectPool<T> pool, float factor) Create an ErodingObjectPool wrapping the given pool using the specified erosion factor.

Method Summary

Modifier and Type	Method and Description
void	addObject() Create an object using the factory or other implementation dependent mechanism, passivate it, and then place it in the idle object pool.
T	borrowObject() Obtains an instance from this 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 this pool.
int	getNumIdle() Return the number of instances currently idle in this pool.
void	invalidateObject(T obj) Invalidates an object from the pool.
void	returnObject(T obj) Returns obj to the pool, unless erosion is triggered, in which case obj is invalidated.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

pool

private final ObjectPool<T> pool

Underlying object pool

factor

private final PoolUtils.ErodingFactor factor

Erosion factor

Constructor Detail

ErodingObjectPool

public ErodingObjectPool(ObjectPool<T> pool,
                         float factor)

Create an ErodingObjectPool wrapping the given pool using the specified erosion factor.

Parameters:

pool - underlying pool

factor - erosion factor - determines the frequency of erosion events

See Also:

factor

Method Detail

borrowObject

public T borrowObject()
               throws java.lang.Exception,
                      java.util.NoSuchElementException,
                      java.lang.IllegalStateException

Obtains an instance from this pool.

Instances returned from this method will have been either newly created with PooledObjectFactory.makeObject() or will be a previously idle object and have been activated with PooledObjectFactory.activateObject(org.apache.commons.pool2.PooledObject<T>) and then validated with PooledObjectFactory.validateObject(org.apache.commons.pool2.PooledObject<T>).

By contract, clients must return the borrowed instance using ObjectPool.returnObject(T), ObjectPool.invalidateObject(T), 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 strictly specified (although it may be specified by implementations).

Specified by:

borrowObject in interface ObjectPool<T>

Returns:

an instance from this pool.

Throws:

java.lang.IllegalStateException - after close has been called on this pool.

java.lang.Exception - when PooledObjectFactory.makeObject() throws an exception.

java.util.NoSuchElementException - when the pool is exhausted and cannot or will not return another instance.

returnObject

public void returnObject(T obj)

Returns obj to the pool, unless erosion is triggered, in which case obj is invalidated. Erosion is triggered when there are idle instances in the pool and more than the erosion factor-determined time has elapsed since the last returnObject activation.

Specified by:

returnObject in interface ObjectPool<T>

Parameters:

obj - object to return or invalidate

See Also:

factor

invalidateObject

public void invalidateObject(T obj)

Invalidates an object from the pool.

By contract, obj must have been obtained using ObjectPool.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<T>

Parameters:

obj - a borrowed instance to be disposed.

addObject

public void addObject()
               throws java.lang.Exception,
                      java.lang.IllegalStateException,
                      java.lang.UnsupportedOperationException

Create an object using the factory or other implementation dependent mechanism, passivate it, and then place it in the idle object pool. addObject is useful for "pre-loading" a pool with idle objects. (Optional operation).

Specified by:

addObject in interface ObjectPool<T>

Throws:

java.lang.Exception - when PooledObjectFactory.makeObject() fails.

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

java.lang.UnsupportedOperationException - when this pool cannot add new idle objects.

getNumIdle

public int getNumIdle()

Return the number of instances currently idle in this pool. This may be considered an approximation of the number of objects that can be borrowed without creating any new instances. Returns a negative value if this information is not available.

Specified by:

getNumIdle in interface ObjectPool<T>

Returns:

the number of instances currently idle in this pool.

getNumActive

public int getNumActive()

Return the number of instances currently borrowed from this pool. Returns a negative value if this information is not available.

Specified by:

getNumActive in interface ObjectPool<T>

Returns:

the number of instances currently borrowed from this pool.

clear

public void clear()
           throws java.lang.Exception,
                  java.lang.UnsupportedOperationException

Clears any objects sitting idle in the pool, releasing any associated resources (optional operation). Idle objects cleared must be PooledObjectFactory.destroyObject(PooledObject).

Specified by:

clear in interface ObjectPool<T>

Throws:

java.lang.UnsupportedOperationException - if this implementation does not support the operation

java.lang.Exception - if the pool cannot be cleared

close

public void close()

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

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

Implementations should silently fail if not all resources can be freed.

Specified by:

close in interface ObjectPool<T>

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object