001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel.util.concurrent;
018
019import java.util.List;
020import java.util.concurrent.AbstractExecutorService;
021import java.util.concurrent.TimeUnit;
022
023/**
024 * A synchronous {@link java.util.concurrent.ExecutorService} which always invokes
025 * the task in the caller thread (just a thread pool facade).
026 * <p/>
027 * There is no task queue, and no thread pool. The task will thus always be executed
028 * by the caller thread in a fully synchronous method invocation.
029 * <p/>
030 * This implementation is very simple and does not support waiting for tasks to complete during shutdown.
031 */
032public class SynchronousExecutorService extends AbstractExecutorService {
033
034    private volatile boolean shutdown;
035
036    public void shutdown() {
037        shutdown = true;
038    }
039
040    public List<Runnable> shutdownNow() {
041        // not implemented
042        return null;
043    }
044
045    public boolean isShutdown() {
046        return shutdown;
047    }
048
049    public boolean isTerminated() {
050        return shutdown;
051    }
052
053    public boolean awaitTermination(long time, TimeUnit unit) throws InterruptedException {
054        // not implemented
055        return true;
056    }
057
058    public void execute(Runnable runnable) {
059        // run the task synchronously
060        runnable.run();
061    }
062
063}