org.picocontainer.gems.adapters

Class ThreadLocalizing

java.lang.Object

org.picocontainer.behaviors.AbstractBehaviorFactory

org.picocontainer.gems.adapters.ThreadLocalizing

All Implemented Interfaces:

Serializable, BehaviorFactory, ComponentFactory

public final class ThreadLocalizing
extends AbstractBehaviorFactory

A ComponentFactory for components kept in ThreadLocal instances.

This factory has two operating modes. By default it ensures, that every thread uses its own component at any time. This mode (ENSURE_THREAD_LOCALITY) makes internal usage of a ThreadLocalized. If the application architecture ensures, that the thread that creates the component is always also the thread that is th only user, you can set the mode THREAD_ENSURES_LOCALITY. In this mode the factory uses a simple Cached that uses a ThreadLocalReference to cache the component.

See the use cases for the subtile difference:

THREAD_ENSURES_LOCALITY is applicable, if the pico container is requested for a thread local addComponent from the working thread e.g. in a web application for a request. In this environment it is ensured, that the request is processed from the same thread and the thread local component is reused, if a previous request was handled in the same thread. Note that thi scenario fails badly, if the thread local component is created because of another cached component indirectly by a dependecy. In this case the cached component already have an instance of the thread local component, that may have been created in another thread, since only the component adapter for the thread local component can ensure a unique component for each thread.

ENSURES_THREAD_LOCALITY solves this problem. In this case the returned component is just a proxy for the thread local component and this proxy ensures, that a new component is created for each thread. Even if another cached component has an indirect dependency on the thread local component, the proxy ensures unique instances. This is vital for a multithreaded application that uses EJBs.

Author:

Jörg Schaible

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	ENSURE_THREAD_LOCALITY ENSURE_THREAD_LOCALITY is the constant for created ComponentAdapter instances, that ensure unique instances of the component by delivering a proxy for the component.
static boolean	THREAD_ENSURES_LOCALITY THREAD_ENSURES_LOCALITY is the constant for created ComponentAdapter instances, that create for the current thread a new component.

Constructor Summary

Constructors

Modifier	Constructor and Description
	ThreadLocalizing() Constructs a wrapping ThreadLocalizing, that ensures the usage of the ThreadLocal.
	ThreadLocalizing(boolean ensure) Constructs a wrapping ThreadLocalizing.
protected	ThreadLocalizing(boolean ensure, ProxyFactory factory) Constructs a wrapping ThreadLocalizing.
	ThreadLocalizing(ProxyFactory proxyFactory) Constructs a wrapping ThreadLocalizing, that ensures the usage of the ThreadLocal.

Method Summary

Methods

Modifier and Type	Method and Description
ComponentAdapter	addComponentAdapter(ComponentMonitor componentMonitor, LifecycleStrategy lifecycleStrategy, Properties componentProperties, ComponentAdapter adapter)
ComponentAdapter	createComponentAdapter(ComponentMonitor componentMonitor, LifecycleStrategy lifecycleStrategy, Properties componentProperties, Object componentKey, Class componentImplementation, Parameter... parameters)

Methods inherited from class org.picocontainer.behaviors.AbstractBehaviorFactory

accept, arePropertiesPresent, getAndRemovePropertiesIfPresentByKey, mergeProperties, removePropertiesIfPresent, verify, wrap

Methods inherited from class java.lang.Object

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

Field Detail

ENSURE_THREAD_LOCALITY

public static final boolean ENSURE_THREAD_LOCALITY

ENSURE_THREAD_LOCALITY is the constant for created ComponentAdapter instances, that ensure unique instances of the component by delivering a proxy for the component.

See Also:

Constant Field Values

THREAD_ENSURES_LOCALITY

public static final boolean THREAD_ENSURES_LOCALITY

THREAD_ENSURES_LOCALITY is the constant for created ComponentAdapter instances, that create for the current thread a new component.

See Also:

Constant Field Values

Constructor Detail

ThreadLocalizing

public ThreadLocalizing()

Constructs a wrapping ThreadLocalizing, that ensures the usage of the ThreadLocal. The Proxy instances are generated by the JDK.

ThreadLocalizing

public ThreadLocalizing(ProxyFactory proxyFactory)

Constructs a wrapping ThreadLocalizing, that ensures the usage of the ThreadLocal.

Parameters:

proxyFactory - The ProxyFactory to use.

ThreadLocalizing

public ThreadLocalizing(boolean ensure)

Constructs a wrapping ThreadLocalizing.

Parameters:

ensure - ENSURE_THREAD_LOCALITY or THREAD_ENSURES_LOCALITY.

ThreadLocalizing

protected ThreadLocalizing(boolean ensure,
                ProxyFactory factory)

Constructs a wrapping ThreadLocalizing.

Parameters:

ensure - ENSURE_THREAD_LOCALITY or THREAD_ENSURES_LOCALITY.

factory - The ProxyFactory to use.

Method Detail

createComponentAdapter

public ComponentAdapter createComponentAdapter(ComponentMonitor componentMonitor,
                                      LifecycleStrategy lifecycleStrategy,
                                      Properties componentProperties,
                                      Object componentKey,
                                      Class componentImplementation,
                                      Parameter... parameters)
                                        throws PicoCompositionException

Specified by:

createComponentAdapter in interface ComponentFactory

Overrides:

createComponentAdapter in class AbstractBehaviorFactory

Throws:

PicoCompositionException

addComponentAdapter

public ComponentAdapter addComponentAdapter(ComponentMonitor componentMonitor,
                                   LifecycleStrategy lifecycleStrategy,
                                   Properties componentProperties,
                                   ComponentAdapter adapter)

Specified by:

addComponentAdapter in interface BehaviorFactory

Overrides:

addComponentAdapter in class AbstractBehaviorFactory