org.glowroot.shaded.google.common.eventbus.AnnotatedSubscriberFinder Maven / Gradle / Ivy
The newest version!
/*
* Copyright (C) 2007 The Guava Authors
*
* 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.glowroot.shaded.google.common.eventbus;
import org.glowroot.shaded.google.common.base.Objects;
import org.glowroot.shaded.google.common.base.Throwables;
import org.glowroot.shaded.google.common.cache.CacheBuilder;
import org.glowroot.shaded.google.common.cache.CacheLoader;
import org.glowroot.shaded.google.common.cache.LoadingCache;
import org.glowroot.shaded.google.common.collect.HashMultimap;
import org.glowroot.shaded.google.common.collect.ImmutableList;
import org.glowroot.shaded.google.common.collect.Maps;
import org.glowroot.shaded.google.common.collect.Multimap;
import org.glowroot.shaded.google.common.reflect.TypeToken;
import org.glowroot.shaded.google.common.util.concurrent.UncheckedExecutionException;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.annotation.Nullable;
/**
* A {@link SubscriberFindingStrategy} for collecting all event subscriber methods that are marked
* with the {@link Subscribe} annotation.
*
* @author Cliff Biffle
* @author Louis Wasserman
*/
class AnnotatedSubscriberFinder implements SubscriberFindingStrategy {
/**
* A thread-safe cache that contains the mapping from each class to all methods in that class and
* all super-classes, that are annotated with {@code @Subscribe}. The cache is shared across all
* instances of this class; this greatly improves performance if multiple EventBus instances are
* created and objects of the same class are registered on all of them.
*/
private static final LoadingCache, ImmutableList> subscriberMethodsCache =
CacheBuilder.newBuilder()
.weakKeys()
.build(new CacheLoader, ImmutableList>() {
@Override
public ImmutableList load(Class concreteClass) throws Exception {
return getAnnotatedMethodsInternal(concreteClass);
}
});
/**
* {@inheritDoc}
*
* This implementation finds all methods marked with a {@link Subscribe} annotation.
*/
@Override
public Multimap, EventSubscriber> findAllSubscribers(Object listener) {
Multimap, EventSubscriber> methodsInListener = HashMultimap.create();
Class clazz = listener.getClass();
for (Method method : getAnnotatedMethods(clazz)) {
Class[] parameterTypes = method.getParameterTypes();
Class eventType = parameterTypes[0];
EventSubscriber subscriber = makeSubscriber(listener, method);
methodsInListener.put(eventType, subscriber);
}
return methodsInListener;
}
private static ImmutableList getAnnotatedMethods(Class clazz) {
try {
return subscriberMethodsCache.getUnchecked(clazz);
} catch (UncheckedExecutionException e) {
throw Throwables.propagate(e.getCause());
}
}
private static final class MethodIdentifier {
private final String name;
private final List> parameterTypes;
MethodIdentifier(Method method) {
this.name = method.getName();
this.parameterTypes = Arrays.asList(method.getParameterTypes());
}
@Override
public int hashCode() {
return Objects.hashCode(name, parameterTypes);
}
@Override
public boolean equals(@Nullable Object o) {
if (o instanceof MethodIdentifier) {
MethodIdentifier ident = (MethodIdentifier) o;
return name.equals(ident.name) && parameterTypes.equals(ident.parameterTypes);
}
return false;
}
}
private static ImmutableList getAnnotatedMethodsInternal(Class clazz) {
Set> supers = TypeToken.of(clazz).getTypes().rawTypes();
Map identifiers = Maps.newHashMap();
for (Class superClazz : supers) {
for (Method superClazzMethod : superClazz.getMethods()) {
if (superClazzMethod.isAnnotationPresent(Subscribe.class)
&& !superClazzMethod.isBridge()) {
Class[] parameterTypes = superClazzMethod.getParameterTypes();
if (parameterTypes.length != 1) {
throw new IllegalArgumentException("Method " + superClazzMethod
+ " has @Subscribe annotation, but requires " + parameterTypes.length
+ " arguments. Event subscriber methods must require a single argument.");
}
MethodIdentifier ident = new MethodIdentifier(superClazzMethod);
if (!identifiers.containsKey(ident)) {
identifiers.put(ident, superClazzMethod);
}
}
}
}
return ImmutableList.copyOf(identifiers.values());
}
/**
* Creates an {@code EventSubscriber} for subsequently calling {@code method} on
* {@code listener}.
* Selects an EventSubscriber implementation based on the annotations on
* {@code method}.
*
* @param listener object bearing the event subscriber method.
* @param method the event subscriber method to wrap in an EventSubscriber.
* @return an EventSubscriber that will call {@code method} on {@code listener}
* when invoked.
*/
private static EventSubscriber makeSubscriber(Object listener, Method method) {
EventSubscriber wrapper;
if (methodIsDeclaredThreadSafe(method)) {
wrapper = new EventSubscriber(listener, method);
} else {
wrapper = new SynchronizedEventSubscriber(listener, method);
}
return wrapper;
}
/**
* Checks whether {@code method} is thread-safe, as indicated by the
* {@link AllowConcurrentEvents} annotation.
*
* @param method subscriber method to check.
* @return {@code true} if {@code subscriber} is marked as thread-safe,
* {@code false} otherwise.
*/
private static boolean methodIsDeclaredThreadSafe(Method method) {
return method.getAnnotation(AllowConcurrentEvents.class) != null;
}
}