com.sun.hk2.component.EventPublishingInhabitant Maven / Gradle / Ivy
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package com.sun.hk2.component;
import java.util.Iterator;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.jvnet.hk2.component.Inhabitant;
import org.jvnet.hk2.component.InhabitantListener;
import org.jvnet.hk2.component.MultiMap;
/**
* An inhabitant that implements InhabitantEventPublisher, and maintains a list
* of listeners to notify for interesting changes of the underlying delegate.
*
* @author Jeff Trent
*
* @since 3.1
*/
public class EventPublishingInhabitant extends AbstractInhabitantImpl {
/**
* Real {@link Inhabitant} object.
*/
protected volatile Inhabitant real;
/**
* Those that will receive events
*/
private volatile CopyOnWriteArraySet listeners;
/* public */EventPublishingInhabitant() {
this.real = null;
}
/* public */EventPublishingInhabitant(Inhabitant delegate) {
this(delegate, null);
}
@SuppressWarnings("unchecked")
/* public */EventPublishingInhabitant(Inhabitant delegate, InhabitantListener listener) {
this.real = (Inhabitant) delegate;
if (null != listener) {
addInhabitantListener(listener);
}
}
@Override
public String toString() {
return getClass().getSimpleName() + "-" + System.identityHashCode(this) +
"(" + typeName() + ", active: " + real + ")";
}
@Override
public String typeName() {
return (null == real) ? null : real.typeName();
}
@Override
public MultiMap metadata() {
return (null == real) ? null : real.metadata();
}
@Override
public void release() {
final boolean wasActive = isInstantiated();
if (null != real) {
real.release();
}
if (wasActive && !isInstantiated()) {
notify(InhabitantListener.EventType.INHABITANT_RELEASED);
}
}
@Override
public boolean isInstantiated() {
return (null != real && real.isInstantiated());
}
@Override
public Class type() {
if (null == real) throw new IllegalStateException();
final boolean wasActive = real.isInstantiated();
Class t = real.type();
if (!wasActive && real.isInstantiated()) {
notify(InhabitantListener.EventType.INHABITANT_ACTIVATED);
}
return t;
}
@SuppressWarnings("unchecked")
@Override
public T get(Inhabitant onBehalfOf) {
if (null == real) {
fetch();
}
final boolean wasActive = real.isInstantiated();
T result = real.get(onBehalfOf);
Inhabitant real = this.real;
if (!wasActive && null != real && real.isInstantiated()) {
notify(InhabitantListener.EventType.INHABITANT_ACTIVATED);
}
return result;
}
protected void fetch() {
throw new IllegalStateException(); // responsibility on derived classes
}
//@Override // for EventPublishingInhabitant
public void addInhabitantListener(InhabitantListener listener) {
if (null == listener) {
throw new IllegalArgumentException();
}
if (null == listeners) {
synchronized (this) {
if (null == listeners) {
listeners = new CopyOnWriteArraySet();
}
}
}
listeners.add(listener);
}
public boolean removeInhabitantListener(InhabitantListener listener) {
return (null == listeners) ? false : listeners.remove(listener);
}
protected void notify(InhabitantListener.EventType eventType) {
if (null != listeners) {
Iterator iter = listeners.iterator();
while (iter.hasNext()) {
InhabitantListener listener = iter.next();
try {
boolean keepListening = listener.inhabitantChanged(eventType, this);
if (!keepListening) {
removeInhabitantListener(listener);
}
} catch (Exception e) {
// don't percolate the exception since it may negatively impact processing
Logger.getAnonymousLogger().log(Level.WARNING, "exception caught from listener", e);
}
}
}
}
}