com.thoughtworks.proxy.toys.pool
Class Pool<T>

java.lang.Object
  com.thoughtworks.proxy.toys.pool.Pool<T>

All Implemented Interfaces:

Serializable

public class Pool<T>
extends Object
implements Serializable

A simple pool implementation that collects its unused components of a specific type automatically.

The pool will only manage instances that were explicitly passed into the pool before. For more sophisticated pooling strategies, derive from this class or wrap it.

The implementation will provide these instances wrapped by a proxy, that will return the instance automatically to the pool, if it falls out of scope and is collected by the garbage collector. Since the pool only returns instances wrapped by a proxy that implements the Poolable interface, this can be used to release the instance manually to the pool also. With an implementation of the Resetter interface each element's status can be reset or the element can be dropped from the pool at all, if it is exhausted.

A client can use the pool's monitor for an improved synchronization. Every time an object is returned to the pool, all waiting Threads of the monitor will be notified. This notification will happen independently of the result of the Resetter.reset(Object) method.

A Pool instance can be created as usual with a builder, but also using various constructors to support dependency injection.

Since:

0.2

Author:

Jörg Schaible, Paul Hammant

See Also:

com.thoughtworks.proxy.toys.pool, Serialized Form

Nested Class Summary

static class	Pool.PoolBuild<T>
protected static class	Pool.PoolingInvoker<T> The Invoker of the proxy.
static class	Pool.PoolModeOrBuild<T>
static class	Pool.PoolResettedBy<T>
static class	Pool.PoolWith<T>

Constructor Summary

Pool(Class<T> type)
Construct an Pool using the StandardProxyFactory for elements that do not have to be resetted.

Pool(Class<T> type, ProxyFactory proxyFactory)
Construct a populated Pool with a specific proxy factory for elements that do not have to be resetted.

Pool(Class<T> type, Resetter<? super T> resetter)
Construct an Pool using the StandardProxyFactory.

Pool(Class<T> type, Resetter<? super T> resetter, ProxyFactory proxyFactory)
Construct a populated Pool with a specific proxy factory.

Pool(Class<T> type, Resetter<? super T> resetter, ProxyFactory proxyFactory, SerializationMode mode)
Construct a populated Pool with a specific proxy factory and a serialization mode.

Method Summary

void	add(T... instances) Add an array of new instances as resources to the pool.
static <T> Pool.PoolResettedBy<T>	create(Class<T> type) Creates a factory for a pool instance which proxy the managed elements in the pool.
T	get() Get an instance from the pool.
int	getAvailable() Return the number of available instances of the pool.
void	release(T object) Release a pool instance manually.
int	size() Retrieve the number of instances managed by the pool.

Methods inherited from class java.lang.Object

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

Constructor Detail

Pool

public Pool(Class<T> type)

Construct an Pool using the StandardProxyFactory for elements that do not have to be resetted.

Parameters:

type - the type of the instances

Since:

1.0

Pool

public Pool(Class<T> type,
            Resetter<? super T> resetter)

Construct an Pool using the StandardProxyFactory.

Parameters:

type - the type of the instances

resetter - the resetter of the pooled elements

Since:

0.2

Pool

public Pool(Class<T> type,
            ProxyFactory proxyFactory)

Construct a populated Pool with a specific proxy factory for elements that do not have to be resetted.

Parameters:

type - the type of the instances

proxyFactory - the proxy factory to use

Since:

1.0

Pool

public Pool(Class<T> type,
            Resetter<? super T> resetter,
            ProxyFactory proxyFactory)

Construct a populated Pool with a specific proxy factory.

Parameters:

type - the type of the instances

resetter - the resetter of the pooled elements

proxyFactory - the proxy factory to use

Since:

0.2

Pool

public Pool(Class<T> type,
            Resetter<? super T> resetter,
            ProxyFactory proxyFactory,
            SerializationMode mode)

Construct a populated Pool with a specific proxy factory and a serialization mode. This mode specify the behavior in case of a serialization of the Pool:

• SerializationMode.STANDARD: the standard mode, i.e. all elements of the pool are also serialized and a NotSerializableException may thrown
• SerializationMode.NONE: no element of the pool is also serialized and it must be populated again after serialization
• SerializationMode.FORCE: all element of the pool are serialized, if possible. Otherwise the pool is empty after serialization and must be populated again.

Parameters:

type - the type of the instances

resetter - the resetter of the pooled elements

proxyFactory - the proxy factory to use

mode - the serialization mode.

Since:

1.0

Method Detail

create

public static <T> Pool.PoolResettedBy<T> create(Class<T> type)

Creates a factory for a pool instance which proxy the managed elements in the pool.

Parameters:

type - the type of the instances

Returns:

return the pool with parameters specified

Since:

1.0

add

public void add(T... instances)

Add an array of new instances as resources to the pool. The pool's monitor will be notified.

Parameters:

instances - the instances

Throws:

NullPointerException - if instance is null

Since:

0.2

get

public T get()

Get an instance from the pool. If no instance is immediately available, the method will check internally for returned objects from the garbage collector. This can be forced by calling System.gc() first.

Returns:

an available instance from the pool or null.

Since:

0.2

release

public void release(T object)

Release a pool instance manually.

Parameters:

object - the instance to release

Throws:

ClassCastException - if object was not Poolable.

IllegalArgumentException - if the object was not from this pool.

Since:

0.2

getAvailable

public int getAvailable()

Return the number of available instances of the pool. The method will also try to collect any pool instance that was freed by the garbage collector. This can be forced by calling System.gc() first. The pool's monitor will be notified, if any object was collected and the Resetter returned the object.

Returns:

the number of available instances.

Since:

0.2

size

public int size()

Retrieve the number of instances managed by the pool.

Returns:

the number of instances.

Since:

0.2