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Java example source code file (Dispatcher.java)
The Dispatcher.java Java example source code/* * Copyright (C) 2014 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 com.google.common.eventbus; import static com.google.common.base.Preconditions.checkNotNull; import com.google.common.collect.Queues; import java.util.Iterator; import java.util.Queue; import java.util.concurrent.ConcurrentLinkedQueue; /** * Handler for dispatching events to subscribers, providing different event ordering guarantees that * make sense for different situations. * * <p>Note: The dispatcher is orthogonal to the subscriber's {@code Executor}. The dispatcher * controls the order in which events are dispatched, while the executor controls how (i.e. on which * thread) the subscriber is actually called when an event is dispatched to it. * * @author Colin Decker */ abstract class Dispatcher { /** * Returns a dispatcher that queues events that are posted reentrantly on a thread that is already * dispatching an event, guaranteeing that all events posted on a single thread are dispatched to * all subscribers in the order they are posted. * * <p>When all subscribers are dispatched to using a direct executor (which dispatches on * the same thread that posts the event), this yields a breadth-first dispatch order on each * thread. That is, all subscribers to a single event A will be called before any subscribers to * any events B and C that are posted to the event bus by the subscribers to A. */ static Dispatcher perThreadDispatchQueue() { return new PerThreadQueuedDispatcher(); } /** * Returns a dispatcher that queues events that are posted in a single global queue. This behavior * matches the original behavior of AsyncEventBus exactly, but is otherwise not especially useful. * For async dispatch, an {@linkplain #immediate() immediate} dispatcher should generally be * preferable. */ static Dispatcher legacyAsync() { return new LegacyAsyncDispatcher(); } /** * Returns a dispatcher that dispatches events to subscribers immediately as they're posted * without using an intermediate queue to change the dispatch order. This is effectively a * depth-first dispatch order, vs. breadth-first when using a queue. */ static Dispatcher immediate() { return ImmediateDispatcher.INSTANCE; } /** * Dispatches the given {@code event} to the given {@code subscribers}. */ abstract void dispatch(Object event, Iterator<Subscriber> subscribers); /** * Implementation of a {@link #perThreadDispatchQueue()} dispatcher. */ private static final class PerThreadQueuedDispatcher extends Dispatcher { // This dispatcher matches the original dispatch behavior of EventBus. /** * Per-thread queue of events to dispatch. */ private final ThreadLocal<Queue Other Java examples (source code examples)Here is a short list of links related to this Java Dispatcher.java source code file: |
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