com.ibm.websphere.asynchbeans.pool

Interface ObjectPool

All Known Subinterfaces:

CustomObjectPool

public interface ObjectPool

This is a pool of reusuable objects of the same type. All object pools implement this type, even custom object pools. An object pool can be obtained by calling the ObjectPoolManager.getPool method. This will reuse an existing pool if one already exists. Otherwise, a new pool is created. Object pools returned by getPool are shared in a JVM.

The ObjectPoolManager.createFastPool method also returns object pools. These are unsynchronized pools that offer a very high level of performance, but they are not thread safe.

Here is an example of usage for an object pool. First, get an ObjectPoolManager instance. See the ObjectPoolManager JavaDoc for an example. Then, request an object pool of the desired class. Use the object pool to manage instances of the class as follows.

 ObjectPoolManager opm = ...;
 ObjectPool vectorPool = opm.getPool(Vector.class);
 Vector pooledVector = null;
 try
 {
   pooledVector = (Vector)vectorPool.getObject();
    Now use the vector.
 }
 finally
 {
   if(pooledVector != null)
   {
     vectorPool.returnObject(pooledVector);
     pooledVector = null;
   }
 }

We recommend the use of a finally block to ensure objects obtained from a pool are returned. If an object is not returned then the memory used by the object can eventually be freed by Java garbage collection.

See Also:

ObjectPool

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.Object	getObject() This method obtains an object from the pool.
void	returnObject(java.lang.Object o) This should be used to return an object to the pool.

Method Detail

getObject

java.lang.Object getObject()

This method obtains an object from the pool. If the pool is empty then we create a new instance.

Returns:

An object of the type defined for the object pool.

returnObject

void returnObject(java.lang.Object o)

This should be used to return an object to the pool. Care needs to be taken to return objects of the correct type only.

Objects that are Collections are automatically cleared when returned to the pool. Collections can only be pooled by the ObjectPool if they support the optional clear method on the Collection interface.

Parameters:

o - The object to be returned to the pool. This must be the expected type.

Throws:

java.lang.UnsupportedOperationException - if the object being returned is a Collection that doesn't support the clear method.