Package org.apache.tomcat.dbcp.pool2
Interface KeyedPooledObjectFactory<K,V>
- Type Parameters:
K- The type of keys managed by this factory.V- Type of element managed by this factory.
- All Known Implementing Classes:
PoolingConnection
public interface KeyedPooledObjectFactory<K,V>
An interface defining life-cycle methods for
instances to be served by a
KeyedObjectPool.
By contract, when an KeyedObjectPool
delegates to a KeyedPooledObjectFactory,
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makeObject(K)is called whenever a new instance is needed. -
activateObject(K, org.apache.tomcat.dbcp.pool2.PooledObject<V>)is invoked on every instance that has beenpassivatedbefore it isborrowedfrom the pool. -
validateObject(K, org.apache.tomcat.dbcp.pool2.PooledObject<V>)may be invoked onactivatedinstances to make sure they can beborrowedfrom the pool.validateObjectmay also be used to test an instance beingreturnedto the pool before it ispassivated. It will only be invoked on an activated instance. -
passivateObjectis invoked on every instance when it is returned to the pool. -
destroyObjectis invoked on every instance when it is being "dropped" from the pool (whether due to the response fromvalidateObject, 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.
- Since:
- 2.0
- See Also:
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Method Summary
Modifier and TypeMethodDescriptionvoidactivateObject(K key, PooledObject<V> p) Reinitializes an instance to be returned by the pool.voiddestroyObject(K key, PooledObject<V> p) Destroys an instance no longer needed by the pool.default voiddestroyObject(K key, PooledObject<V> p, DestroyMode destroyMode) Destroys an instance no longer needed by the pool, using the providedDestroyMode.makeObject(K key) Creates an instance that can be served by the pool and wrap it in aPooledObjectto be managed by the pool.voidpassivateObject(K key, PooledObject<V> p) Uninitializes an instance to be returned to the idle object pool.booleanvalidateObject(K key, PooledObject<V> p) Ensures that the instance is safe to be returned by the pool.
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Method Details
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activateObject
Reinitializes an instance to be returned by the pool.- Parameters:
key- the key used when selecting the objectp- aPooledObjectwrapping the instance to be activated- Throws:
Exception- if there is a problem activatingobj, this exception may be swallowed by the pool.- See Also:
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destroyObject
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
objwill 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- the key used when selecting the instancep- aPooledObjectwrapping the instance to be destroyed- Throws:
Exception- should be avoided as it may be swallowed by the pool implementation.- See Also:
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destroyObject
Destroys an instance no longer needed by the pool, using the providedDestroyMode.- Parameters:
key- the key used when selecting the instancep- aPooledObjectwrapping the instance to be destroyeddestroyMode- DestroyMode providing context to the factory- Throws:
Exception- should be avoided as it may be swallowed by the pool implementation.- Since:
- 2.9.0
- See Also:
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makeObject
Creates an instance that can be served by the pool and wrap it in aPooledObjectto be managed by the pool.- Parameters:
key- the key used when constructing the object- Returns:
- a
PooledObjectwrapping an instance that can be served by the pool. - Throws:
Exception- if there is a problem creating a new instance, this will be propagated to the code requesting an object.
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passivateObject
Uninitializes an instance to be returned to the idle object pool.- Parameters:
key- the key used when selecting the objectp- aPooledObjectwrapping the instance to be passivated- Throws:
Exception- if there is a problem passivatingobj, this exception may be swallowed by the pool.- See Also:
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validateObject
Ensures that the instance is safe to be returned by the pool.- Parameters:
key- the key used when selecting the objectp- aPooledObjectwrapping the instance to be validated- Returns:
falseifobjis not valid and should be dropped from the pool,trueotherwise.
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