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public interface PoolableObjectFactory
An interface defining life-cycle methods for
instances to be served by an ObjectPool
.
By contract, when an ObjectPool
delegates to a PoolableObjectFactory
,
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
is 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.
PoolableObjectFactory
must be thread-safe. The only promise
an ObjectPool
makes is that the same instance of an object will not
be passed to more than one method of a PoolableObjectFactory
at a time.
ObjectPool
Method Summary | |
---|---|
void |
activateObject(Object obj)
Reinitialize an instance to be returned by the pool. |
void |
destroyObject(Object obj)
Destroys an instance no longer needed by the pool. |
Object |
makeObject()
Creates an instance that can be served by the pool. |
void |
passivateObject(Object obj)
Uninitialize an instance to be returned to the idle object pool. |
boolean |
validateObject(Object obj)
Ensures that the instance is safe to be returned by the pool. |
Method Detail |
---|
Object makeObject() throws Exception
activated
. They will not be
activated before being served by the pool.
Exception
- if there is a problem creating a new instance,
this will be propagated to the code requesting an object.void destroyObject(Object obj) throws Exception
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.
obj
- the instance to be destroyed
Exception
- should be avoided as it may be swallowed by
the pool implementation.validateObject(java.lang.Object)
,
ObjectPool.invalidateObject(java.lang.Object)
boolean validateObject(Object obj)
false
if obj
should be destroyed.
obj
- the instance to be validated
false
if obj
is not valid and should
be dropped from the pool, true
otherwise.void activateObject(Object obj) throws Exception
obj
- the instance to be activated
Exception
- if there is a problem activating obj
,
this exception may be swallowed by the pool.destroyObject(java.lang.Object)
void passivateObject(Object obj) throws Exception
obj
- the instance to be passivated
Exception
- if there is a problem passivating obj
,
this exception may be swallowed by the pool.destroyObject(java.lang.Object)
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