org.jboss.weld.event.FastEvent Maven / Gradle / Ivy
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* Copyright 2013, Red Hat, Inc., and individual contributors
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.jboss.weld.event;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.util.Set;
import javax.enterprise.event.Event;
import javax.enterprise.inject.Instance;
import javax.enterprise.inject.spi.EventMetadata;
import javax.enterprise.inject.spi.InjectionPoint;
import javax.enterprise.inject.spi.ObserverMethod;
import javax.enterprise.util.TypeLiteral;
import org.jboss.weld.injection.attributes.WeldInjectionPointAttributes;
import org.jboss.weld.manager.BeanManagerImpl;
import com.google.common.collect.ImmutableSet;
/**
* An optimized internal facility for dispatching events.
*
*
* FastEvent eliminates most of the overhead associated with request dispatching by resolving observer methods upfront. It is therefore suitable for cases when
* certain event is dispatched repeatedly. A FastEvent instance should be created once for a given event type / qualifiers combination and then reused every
* time a given event is dispatched.
*
*
*
* FastEvent provides a subset of functionality provided by {@link Event} and these additional constraints apply to its usage:
*
*
*
* - Event type and qualifiers must be known at FastEvent construction time. The actual type of the event object passed to the {@link #fire(Object)} method is
* not considered for observer method resolution.
* - Events dispatched using FastEvent are always delivered immediately. If an observer method is transactional it will be notified immediately and not during
* the matching transaction phase.
* - FastEvent is not serializable
*
*
*
* These constraints should always be carefully considered when deciding whether to use FastEvent or not. FastEvent is an internal construct and should
* not be used by an application.
*
*
* @author Jozef Hartinger
*
* @param event type
*/
public class FastEvent {
@SuppressWarnings("serial")
private static final Type EVENT_METADATA_INSTANCE_TYPE = new TypeLiteral>() {
}.getType();
/**
* Determines whether any of the resolved observer methods is either extension-provided or contains an injection point with {@link EventMetadata} type.
*/
private static boolean isMetadataRequired(Set> resolvedObserverMethods) {
for (ObserverMethod observer : resolvedObserverMethods) {
if (observer instanceof ObserverMethodImpl) {
ObserverMethodImpl observerImpl = (ObserverMethodImpl) observer;
for (WeldInjectionPointAttributes ip : observerImpl.getInjectionPoints()) {
Type type = ip.getType();
if (EventMetadata.class.equals(type) || EVENT_METADATA_INSTANCE_TYPE.equals(type)) {
return true;
}
}
} else {
return true;
}
}
return false;
}
/**
* Same as {@link #of(Class, BeanManagerImpl, Annotation...)}, just the accessible lenient observer notifier is used for observer method resolution
*/
public static FastEvent of(Class type, BeanManagerImpl manager, Annotation... qualifiers) {
return of(type, manager, manager.getAccessibleLenientObserverNotifier(), qualifiers);
}
/**
* Constructs a new FastEvent instance
* @param type the event type
* @param manager the bean manager
* @param notifier the notifier to be used for observer method resolution
* @param qualifiers the event qualifiers
* @return
*/
public static FastEvent of(Class type, BeanManagerImpl manager, ObserverNotifier notifier, Annotation... qualifiers) {
Set> resolvedObserverMethods = notifier. resolveObserverMethods(notifier.buildEventResolvable(type, qualifiers));
if (isMetadataRequired(resolvedObserverMethods)) {
EventMetadata metadata = new EventMetadataImpl(type, qualifiers);
CurrentEventMetadata metadataService = manager.getServices().get(CurrentEventMetadata.class);
return new FastEventWithMetadataPropagation(resolvedObserverMethods, metadata, metadataService);
} else {
return new FastEvent(resolvedObserverMethods);
}
}
private final Set> resolvedObserverMethods;
private FastEvent(Set> resolvedObserverMethods) {
this.resolvedObserverMethods = resolvedObserverMethods;
}
public void fire(T event) {
for (ObserverMethod observer : resolvedObserverMethods) {
observer.notify(event);
}
}
private static class FastEventWithMetadataPropagation extends FastEvent {
private final EventMetadata metadata;
private final CurrentEventMetadata metadataService;
private FastEventWithMetadataPropagation(Set> resolvedObserverMethods, EventMetadata metadata,
CurrentEventMetadata metadataService) {
super(resolvedObserverMethods);
this.metadata = metadata;
this.metadataService = metadataService;
}
@Override
public void fire(T event) {
if (metadata != null) {
metadataService.push(metadata);
}
try {
super.fire(event);
} finally {
if (metadata != null) {
metadataService.pop();
}
}
}
}
private static class EventMetadataImpl implements EventMetadata {
private final Set qualifiers;
private final Type type;
private EventMetadataImpl(Type type, Annotation... qualifiers) {
this.type = type;
this.qualifiers = ImmutableSet.copyOf(qualifiers);
}
@Override
public Set getQualifiers() {
return qualifiers;
}
@Override
public InjectionPoint getInjectionPoint() {
return null;
}
@Override
public Type getType() {
return type;
}
}
}