org.apache.commons.pool2

Class PoolUtils.ErodingKeyedObjectPool<K,V>

java.lang.Object

org.apache.commons.pool2.PoolUtils.ErodingKeyedObjectPool<K,V>

All Implemented Interfaces:

KeyedObjectPool<K,V>

Direct Known Subclasses:

PoolUtils.ErodingPerKeyKeyedObjectPool

Enclosing class:

PoolUtils

private static class PoolUtils.ErodingKeyedObjectPool<K,V>
extends java.lang.Object
implements KeyedObjectPool<K,V>

Decorates a keyed 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	erodingFactor Erosion factor
private KeyedObjectPool<K,V>	keyedPool Underlying pool

Constructor Summary

Constructors

Modifier	Constructor and Description
	ErodingKeyedObjectPool(KeyedObjectPool<K,V> keyedPool, float factor) Create an ErodingObjectPool wrapping the given pool using the specified erosion factor.
protected	ErodingKeyedObjectPool(KeyedObjectPool<K,V> keyedPool, PoolUtils.ErodingFactor erodingFactor) Create an ErodingObjectPool wrapping the given pool using the specified erosion factor.

Method Summary

Modifier and Type	Method and Description
void	addObject(K key) Create an object using the factory or other implementation dependent mechanism, passivate it, and then place it in the idle object pool.
V	borrowObject(K key) Obtains an instance from this pool for the specified key.
void	clear() Clears the pool, removing all pooled instances (optional operation).
void	clear(K key) Clears the specified pool, removing all pooled instances corresponding to the given key (optional operation).
void	close() Close this pool, and free any resources associated with it.
protected PoolUtils.ErodingFactor	getErodingFactor(K key) Returns the eroding factor for the given key
protected KeyedObjectPool<K,V>	getKeyedPool() Returns the underlying pool
int	getNumActive() Returns the total number of instances current borrowed from this pool but not yet returned.
int	getNumActive(K key) Returns the number of instances currently borrowed from but not yet returned to the pool corresponding to the given key.
int	getNumIdle() Returns the total number of instances currently idle in this pool.
int	getNumIdle(K key) Returns the number of instances corresponding to the given key currently idle in this pool.
void	invalidateObject(K key, V obj) Invalidates an object from the pool.
void	returnObject(K key, V 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

keyedPool

private final KeyedObjectPool<K,V> keyedPool

Underlying pool

erodingFactor

private final PoolUtils.ErodingFactor erodingFactor

Erosion factor

Constructor Detail

ErodingKeyedObjectPool

public ErodingKeyedObjectPool(KeyedObjectPool<K,V> keyedPool,
                              float factor)

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

Parameters:

keyedPool - underlying pool

factor - erosion factor - determines the frequency of erosion events

See Also:

erodingFactor

ErodingKeyedObjectPool

protected ErodingKeyedObjectPool(KeyedObjectPool<K,V> keyedPool,
                                 PoolUtils.ErodingFactor erodingFactor)

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

Parameters:

keyedPool - underlying pool - must not be null

erodingFactor - erosion factor - determines the frequency of erosion events

See Also:

#factor

Method Detail

borrowObject

public V borrowObject(K key)
               throws java.lang.Exception,
                      java.util.NoSuchElementException,
                      java.lang.IllegalStateException

Obtains an instance from this pool for the specified key.

Instances returned from this method will have been either newly created with makeObject or will be a previously idle object and have been activated with activateObject and then (optionally) validated with validateObject.

By contract, clients must return the borrowed object using returnObject, invalidateObject, or a related method as defined in an implementation or sub-interface, using a key that is equivalent to the one used to borrow the instance in the first place.

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 KeyedObjectPool<K,V>

Parameters:

key - the key used to obtain the object

Returns:

an instance from this pool.

Throws:

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

java.lang.Exception - when makeObject throws an exception

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

returnObject

public void returnObject(K key,
                         V obj)
                  throws java.lang.Exception

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 associated with the given key and more than the configured erosion factor time has elapsed since the last returnObject activation.

Specified by:

returnObject in interface KeyedObjectPool<K,V>

Parameters:

obj - object to return or invalidate

key - key

Throws:

java.lang.IllegalStateException - if an attempt is made to return an object to the pool that is in any state other than allocated (i.e. borrowed). Attempting to return an object more than once or attempting to return an object that was never borrowed from the pool will trigger this exception.

java.lang.Exception - if an instance cannot be returned to the pool

See Also:

erodingFactor

getErodingFactor

protected PoolUtils.ErodingFactor getErodingFactor(K key)

Returns the eroding factor for the given key

Parameters:

key - key

Returns:

eroding factor for the given keyed pool

invalidateObject

public void invalidateObject(K key,
                             V 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 using a key that is equivalent to the one used to borrow the Object in the first place.

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 KeyedObjectPool<K,V>

Parameters:

key - the key used to obtain the object

obj - a borrowed instance to be returned.

addObject

public void addObject(K key)
               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 KeyedObjectPool<K,V>

Parameters:

key - the key a new instance should be added to

Throws:

java.lang.Exception - when KeyedPooledObjectFactory.makeObject(K) fails.

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

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

getNumIdle

public int getNumIdle()

Returns the total number of instances currently idle in this pool. Returns a negative value if this information is not available.

Specified by:

getNumIdle in interface KeyedObjectPool<K,V>

Returns:

the total number of instances currently idle in this pool. =

getNumIdle

public int getNumIdle(K key)

Returns the number of instances corresponding to the given key currently idle in this pool. Returns a negative value if this information is not available.

Specified by:

getNumIdle in interface KeyedObjectPool<K,V>

Parameters:

key - the key to query

Returns:

the number of instances corresponding to the given key currently idle in this pool.

getNumActive

public int getNumActive()

Returns the total number of instances current borrowed from this pool but not yet returned. Returns a negative value if this information is not available.

Specified by:

getNumActive in interface KeyedObjectPool<K,V>

Returns:

the total number of instances current borrowed from this pool but not yet returned.

getNumActive

public int getNumActive(K key)

Returns the number of instances currently borrowed from but not yet returned to the pool corresponding to the given key. Returns a negative value if this information is not available.

Specified by:

getNumActive in interface KeyedObjectPool<K,V>

Parameters:

key - the key to query

Returns:

the number of instances currently borrowed from but not yet returned to the pool corresponding to the given key. =

clear

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

Clears the pool, removing all pooled instances (optional operation).

Specified by:

clear in interface KeyedObjectPool<K,V>

Throws:

java.lang.UnsupportedOperationException - when this implementation doesn't support the operation

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

clear

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

Clears the specified pool, removing all pooled instances corresponding to the given key (optional operation).

Specified by:

clear in interface KeyedObjectPool<K,V>

Parameters:

key - the key to clear

Throws:

java.lang.UnsupportedOperationException - when this implementation doesn't support the operation

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

close

public void close()

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.

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

Specified by:

close in interface KeyedObjectPool<K,V>

getKeyedPool

protected KeyedObjectPool<K,V> getKeyedPool()

Returns the underlying pool

Returns:

the keyed pool that this ErodingKeyedObjectPool wraps

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object