org.sadun.util.pool
Class ObjectPool

java.lang.Object
  org.sadun.util.pool.ObjectPool

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

ObjectPool

public class ObjectPool

extends java.lang.Object

implements java.io.Serializable

An object pool, which holds n identical copies of an object and allows access and release of each of them.

An object can be created by providing its class - in which case the default constructor will be used to create the instances; or by providing the construction parameters as an object array.

Optionally, after creation, a Setup object can be used to differentiate or further set up the created object.

This version supports Enterprise Java Beans creation via a JNDI name and home interface

Version:

2.2

Author:

C. Sadun

See Also:

Serialized Form

Nested Class Summary

static class	ObjectPool.BaseFactory A base implementation of ExtendedObjectPool.Factory relying on reflection, holding a Class object, an optional parameter array and an optional Setup object.
static interface	ObjectPool.Factory If an object to be pooled can't be constructed directly by invoking a constructor, a Factory can be provided to do the construction job.
static class	ObjectPool.ObjectFactory An ExtendedObjectPool.Factory implementation which uses reflection to create instances of a certain class.
static class	ObjectPool.ObjectPoolException An exception thrown in case of pooling operation errors.
protected static class	ObjectPool.PooledObjectWrapper

Field Summary

protected java.util.Set	free
protected ObjectPool.PooledObjectWrapper[]	pool
protected java.util.Set	used

Constructor Summary

ObjectPool(int n, java.lang.Class cls)
Create a pool of n object of the given class using the default constructor.

ObjectPool(int n, java.lang.Class cls, java.lang.Object[] params)
Create a pool of n object of the given class using the given construction parameters.

ObjectPool(int n, java.lang.Class cls, java.lang.Object[] params, Setup ps)
Create a pool of n object of the given class using the given construction parameters.

ObjectPool(int n, ObjectPool.Factory factory)
Create a pool of n objects using the given factory

ObjectPool(int n, java.lang.String clsName)
Create a pool of n object of the given class (by name) using the default constructor.

ObjectPool(int n, java.lang.String clsName, java.lang.Object[] params)
Create a pool of n object of the given class (by name) using the given construction parameters.

ObjectPool(int n, java.lang.String clsName, java.lang.Object[] params, Setup ps)
Create a pool of n object of the given class (by name) using the given construction parameters.

Method Summary

java.lang.Object	acquire() Attempt to acquire an object.
java.lang.Object	acquire(boolean waitIfUnavailable) Attempt to acquire an object.
java.lang.Object	acquire(int i) Attempt to acquire the i-th object.
void	destroy(boolean waitForReleasedObjects) Destroys all the objects in the pool by invoking the Factory.destroy() method on the pool's object factory.
protected ObjectPool.Factory	getFactory() Returns the factory.
int	getFreeCount() Return the number of available objects in the pool
java.lang.Class	getObjectType() Return the object type pooled by this pool
int	getSize() Return the size of the pool
int	getUsedCount() Return the number of used objects in the pool
static ObjectPool	newPool(int poolSize, java.lang.String clsName) A convenience method to create a new pool of objects of a given class, by name, using their default constructor.
static ObjectPool	newPool(int poolSize, java.lang.String clsName, java.lang.Object[] params) A convenience method to create a new pool of objects of a given class, by name, using the given parameters.
void	release(int i) Releases the i-th object, notifying the waiting thread (if any) that one pooled object has become available.
void	release(java.lang.Object obj) Release an object, notifying waiting thread (if any) that one pooled object has become available.
void	release(java.lang.Object obj, boolean releaseWaitingCalls) Release an object.
java.lang.Object	renew(java.lang.Object obj) Renew one object in the pool.
protected void	setFactory(ObjectPool.Factory factory) Sets the factory.
java.lang.String	toString() Return a string description of the pool

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

free

protected java.util.Set free

used

protected java.util.Set used

pool

protected ObjectPool.PooledObjectWrapper[] pool

Constructor Detail

ObjectPool

public ObjectPool(int n,
                  ObjectPool.Factory factory)

Create a pool of n objects using the given factory

ObjectPool

public ObjectPool(int n,
                  java.lang.String clsName,
                  java.lang.Object[] params,
                  Setup ps)
           throws java.lang.ClassNotFoundException

Create a pool of n object of the given class (by name) using the given construction parameters.

If some post-construction setup is needed, it can be provided as an Setup object.

Parameters:

n - the size of the pool

clsName - the name of the class of the objects to pool

params - the construction parameters, or null

Throws:

java.lang.ClassNotFoundException - if the given class name cannot be resolved

ObjectPool

public ObjectPool(int n,
                  java.lang.String clsName,
                  java.lang.Object[] params)
           throws java.lang.ClassNotFoundException

Create a pool of n object of the given class (by name) using the given construction parameters.

Parameters:

n - the size of the pool

clsName - the name of the class of the objects to pool

params - the construction parameters, or null

Throws:

java.lang.ClassNotFoundException - if the given class name cannot be resolved

ObjectPool

public ObjectPool(int n,
                  java.lang.String clsName)
           throws java.lang.ClassNotFoundException

Create a pool of n object of the given class (by name) using the default constructor.

Parameters:

n - the size of the pool

clsName - the name of the class of the objects to pool

Throws:

java.lang.ClassNotFoundException - if the given class name cannot be resolved

ObjectPool

public ObjectPool(int n,
                  java.lang.Class cls,
                  java.lang.Object[] params,
                  Setup ps)

Create a pool of n object of the given class using the given construction parameters.

If some post-construction setup is needed, it can be provided as an Setup object.

Parameters:

n - the size of the pool

cls - the class of the objects to pool

params - the construction parameters, or null

ObjectPool

public ObjectPool(int n,
                  java.lang.Class cls,
                  java.lang.Object[] params)

Create a pool of n object of the given class using the given construction parameters.

Parameters:

n - the size of the pool

cls - the class of the objects to pool

params - the construction parameters, or null

ObjectPool

public ObjectPool(int n,
                  java.lang.Class cls)

Create a pool of n object of the given class using the default constructor.

Parameters:

n - the size of the pool

cls - the class of the objects to pool

Method Detail

getFreeCount

public int getFreeCount()

Return the number of available objects in the pool

Returns:

the number of available objects in the pool

getUsedCount

public int getUsedCount()

Return the number of used objects in the pool

Returns:

the number of used objects in the pool

getSize

public int getSize()

Return the size of the pool

Returns:

the size of the pool

acquire

public java.lang.Object acquire(boolean waitIfUnavailable)

Attempt to acquire an object.

Parameters:

waitIfUnavailable - if true, in case all the pooled objects are used, the call will block until an object is released. If false, in the same condition the method returns null.

Returns:

a pooled object

acquire

public java.lang.Object acquire()

Attempt to acquire an object.

If there aren't any objects available, this method blocks until one becomes available.

Returns:

a pooled object

acquire

public java.lang.Object acquire(int i)

Attempt to acquire the i-th object.

If the object is not available, this method blocks until the object becomes available.

Returns:

a pooled object

release

public void release(int i)

Releases the i-th object, notifying the waiting thread (if any) that one pooled object has become available.

release

public void release(java.lang.Object obj,
                    boolean releaseWaitingCalls)

Release an object.

Parameters:

releaseWaitingCalls - if true, the method notifies waiting objects that one pooled object has become available.

release

public void release(java.lang.Object obj)

Release an object, notifying waiting thread (if any) that one pooled object has become available.

renew

public java.lang.Object renew(java.lang.Object obj)

Renew one object in the pool.

A new instance is created substituting the passed object in the pool, and the new instance is returned. The object is released() but any thread waiting on that object shifts waiting for another object.

toString

public java.lang.String toString()

Return a string description of the pool

Returns:

a string description of the pool

newPool

public static ObjectPool newPool(int poolSize,
                                 java.lang.String clsName)
                          throws ObjectPool.ObjectPoolException

A convenience method to create a new pool of objects of a given class, by name, using their default constructor.

Parameters:

poolSize - the size of the pool

clsName - the name of the class of the pooled objects

Throws:

ObjectPool.ObjectPoolException - if the pool cannot be initialized

newPool

public static ObjectPool newPool(int poolSize,
                                 java.lang.String clsName,
                                 java.lang.Object[] params)
                          throws ObjectPool.ObjectPoolException

A convenience method to create a new pool of objects of a given class, by name, using the given parameters.

Parameters:

poolSize - the size of the pool

clsName - the name of the class of the pooled objects

params - the parameters used to initialize the objects of the pool

Throws:

ObjectPool.ObjectPoolException - if the pool cannot be initialized

getObjectType

public java.lang.Class getObjectType()

Return the object type pooled by this pool

getFactory

protected ObjectPool.Factory getFactory()

Returns the factory.

Returns:

Factory

setFactory

protected void setFactory(ObjectPool.Factory factory)

Sets the factory.

Parameters:

factory - The factory to set

destroy

public void destroy(boolean waitForReleasedObjects)

Destroys all the objects in the pool by invoking the Factory.destroy() method on the pool's object factory.

Parameters:

waitForReleasedObjects - waits until all the objects are released before destroying them