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Java example source code file (AsyncService.java)
The AsyncService.java Java example source code/** * Copyright (C) 2010 Google Inc. * * 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.inject.service; import com.google.common.base.Preconditions; import java.util.concurrent.Callable; import java.util.concurrent.ExecutorService; import java.util.concurrent.Future; import java.util.concurrent.FutureTask; /** * An asynchronous implementation of {@link com.google.inject.service.Service} * that provides convenience callbacks to create your own services. * * @author dhanji@gmail.com (Dhanji R. Prasanna) */ public abstract class AsyncService implements Service { private static final Runnable DO_NOTHING = new Runnable() { @Override public void run() {} }; private final ExecutorService executor; private volatile State state; public AsyncService(ExecutorService executor) { this.executor = executor; } public synchronized final Future<State> start() { Preconditions.checkState(state != State.STOPPED, "Cannot restart a service that has been stopped"); // Starts are idempotent. if (state == State.STARTED) { return new FutureTask<State>(DO_NOTHING, State.STARTED); } return executor.submit(new Callable<State>() { public State call() { onStart(); return state = State.STARTED; } }); } /** * Called back when this service must do its start work. Typically occurs * in a background thread. The result of this method is returned to the * original caller of {@link Service#start()} and can thus be used to * return a status message after start completes (or fails as the case * may be). */ protected abstract void onStart(); public synchronized final Future<State> stop() { Preconditions.checkState(state != null, "Must start this service before you stop it!"); // Likewise, stops are idempotent. if (state == State.STOPPED) { return new FutureTask<State>(DO_NOTHING, State.STOPPED); } return executor.submit(new Callable<State>() { public State call() { onStop(); return state = State.STOPPED; } }); } /** * Called back when this service must shutdown. Typically occurs * in a background thread. The result of this method is returned to the * original caller of {@link Service#stop()} and can thus be used to * return a status message after stop completes (or fails as the case * may be). */ protected abstract void onStop(); public final State state() { return state; } } Other Java examples (source code examples)Here is a short list of links related to this Java AsyncService.java source code file: |
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