Apache Commons Pool 2.13.0 · org.apache.commons.pool2.KeyedPooledObjectFactory

An interface defining life-cycle methods for instances to be served by a KeyedObjectPool.

By contract, when an KeyedObjectPool delegates to a KeyedPooledObjectFactory,

makeObject is called whenever a new instance is needed.
activateObject is invoked on every instance that has been passivated before it is borrowed from the pool.
validateObject may be invoked on activated instances to make sure they can be borrowed from the pool. validateObject may also be used to test an instance being returned to the pool before it is passivated. It will only be invoked on an activated instance.
passivateObject is invoked on every instance when it is returned to the pool.
destroyObject is invoked on every instance when it is being "dropped" from the pool (whether due to the response from validateObject, or for reasons specific to the pool implementation.) There is no guarantee that the instance being destroyed will be considered active, passive or in a generally consistent state.

KeyedPooledObjectFactory must be thread-safe. The only promise an KeyedObjectPool makes is that the same instance of an object will not be passed to more than one method of a KeyedPooledObjectFactory at a time.

While clients of a KeyedObjectPool borrow and return instances of the underlying value type V, the factory methods act on instances of PooledObject<V>. These are the object wrappers that pools use to track and maintain state informations about the objects that they manage.

Method Summary

Modifier and Type	Method and Description
public void	activateObject(K the key used when selecting the object key, PooledObject<V> a `PooledObject` wrapping the instance to be activated p) Reinitializes an instance to be returned by the pool.
public void	destroyObject(K the key used when selecting the instance key, PooledObject<V> a `PooledObject` wrapping the instance to be destroyed p) Destroys an instance no longer needed by the pool.
public default void	destroyObject(final K the key used when selecting the instance key, final PooledObject<V> a `PooledObject` wrapping the instance to be destroyed p, final DestroyMode DestroyMode providing context to the factory destroyMode) Destroys an instance no longer needed by the pool, using the provided `DestroyMode`.
public PooledObject<V>	Returns: a `PooledObject` wrapping an instance that can be served by the pool. makeObject(K the key used when constructing the object key) Creates an instance that can be served by the pool and wrap it in a `PooledObject` to be managed by the pool.
public void	passivateObject(K the key used when selecting the object key, PooledObject<V> a `PooledObject` wrapping the instance to be passivated p) Uninitializes an instance to be returned to the idle object pool.
public boolean	Returns: `false` if `obj` is not valid and should be dropped from the pool, `true` otherwise. validateObject(K the key used when selecting the object key, PooledObject<V> a `PooledObject` wrapping the instance to be validated p) Ensures that the instance is safe to be returned by the pool.

Method Detail

activateObject back to summary

activateObject	back to summary
public void activateObject(K key, PooledObject<V> p) throws Exception Reinitializes an instance to be returned by the pool. Parameters key:K the key used when selecting the object p:PooledObject<V> a `PooledObject` wrapping the instance to be activated Exceptions Exception: if there is a problem activating `obj`, this exception may be swallowed by the pool. See Also `destroyObject`

public void activateObject(K key, PooledObject<V> p) throws Exception

Reinitializes an instance to be returned by the pool.

Parameters

key:K: the key used when selecting the object
p:PooledObject<V>: a PooledObject wrapping the instance to be activated

Exceptions

Exception:: if there is a problem activating obj, this exception may be swallowed by the pool.

See Also

destroyObject

destroyObject back to summary

destroyObject	back to summary
public void destroyObject(K key, PooledObject<V> p) throws Exception Destroys an instance no longer needed by the pool. It is important for implementations of this method to be aware that there is no guarantee about what state `obj` will be in and the implementation should be prepared to handle unexpected errors. Also, an implementation must take in to consideration that instances lost to the garbage collector may never be destroyed. Parameters key:K the key used when selecting the instance p:PooledObject<V> a `PooledObject` wrapping the instance to be destroyed Exceptions Exception: should be avoided as it may be swallowed by the pool implementation. See Also `validateObject`, `KeyedObjectPool#invalidateObject`

public void destroyObject(K key, PooledObject<V> p) throws Exception

Destroys an instance no longer needed by the pool.

It is important for implementations of this method to be aware that there is no guarantee about what state obj will be in and the implementation should be prepared to handle unexpected errors.

Also, an implementation must take in to consideration that instances lost to the garbage collector may never be destroyed.

Parameters

key:K: the key used when selecting the instance
p:PooledObject<V>: a PooledObject wrapping the instance to be destroyed

Exceptions

Exception:: should be avoided as it may be swallowed by the pool implementation.

destroyObject back to summary

destroyObject	back to summary
public default void destroyObject(final K key, final PooledObject<V> p, final DestroyMode destroyMode) throws Exception Destroys an instance no longer needed by the pool, using the provided `DestroyMode`. Parameters key:K the key used when selecting the instance p:PooledObject<V> a `PooledObject` wrapping the instance to be destroyed destroyMode:DestroyMode DestroyMode providing context to the factory Exceptions Exception: should be avoided as it may be swallowed by the pool implementation. Since 2.9.0 See Also `validateObject`, `KeyedObjectPool#invalidateObject`, `destroyObject(Object, PooledObject)`, `DestroyMode`

public default void destroyObject(final K key, final PooledObject<V> p, final DestroyMode destroyMode) throws Exception

Destroys an instance no longer needed by the pool, using the provided DestroyMode.

Parameters

key:K: the key used when selecting the instance
p:PooledObject<V>: a PooledObject wrapping the instance to be destroyed
destroyMode:DestroyMode: DestroyMode providing context to the factory

Exceptions

Exception:: should be avoided as it may be swallowed by the pool implementation.

Since

2.9.0

makeObject back to summary

makeObject	back to summary
public PooledObject<V> makeObject(K key) throws Exception Creates an instance that can be served by the pool and wrap it in a `PooledObject` to be managed by the pool. Parameters key:K the key used when constructing the object Returns:PooledObject<V> a `PooledObject` wrapping an instance that can be served by the pool. Exceptions Exception: if there is a problem creating a new instance, this will be propagated to the code requesting an object.

public PooledObject<V> makeObject(K key) throws Exception

Creates an instance that can be served by the pool and wrap it in a PooledObject to be managed by the pool.

Parameters

key:K: the key used when constructing the object

Returns:PooledObject<V>

a PooledObject wrapping an instance that can be served by the pool.

Exceptions

Exception:: if there is a problem creating a new instance, this will be propagated to the code requesting an object.

passivateObject back to summary

passivateObject	back to summary
public void passivateObject(K key, PooledObject<V> p) throws Exception Uninitializes an instance to be returned to the idle object pool. Parameters key:K the key used when selecting the object p:PooledObject<V> a `PooledObject` wrapping the instance to be passivated Exceptions Exception: if there is a problem passivating `obj`, this exception may be swallowed by the pool. See Also `destroyObject`

public void passivateObject(K key, PooledObject<V> p) throws Exception

Uninitializes an instance to be returned to the idle object pool.

Parameters

key:K: the key used when selecting the object
p:PooledObject<V>: a PooledObject wrapping the instance to be passivated

Exceptions

Exception:: if there is a problem passivating obj, this exception may be swallowed by the pool.

See Also

destroyObject

validateObject back to summary

validateObject	back to summary
public boolean validateObject(K key, PooledObject<V> p) Ensures that the instance is safe to be returned by the pool. Parameters key:K the key used when selecting the object p:PooledObject<V> a `PooledObject` wrapping the instance to be validated Returns:boolean `false` if `obj` is not valid and should be dropped from the pool, `true` otherwise.

public boolean validateObject(K key, PooledObject<V> p)

Ensures that the instance is safe to be returned by the pool.

Parameters

key:K: the key used when selecting the object
p:PooledObject<V>: a PooledObject wrapping the instance to be validated

Returns:boolean

false if obj is not valid and should be dropped from the pool, true otherwise.

public Interface KeyedPooledObjectFactory<K, V>

Method Summary

Method Detail