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     */
017    package org.apache.camel.util.concurrent;
018    
019    import java.util.List;
020    import java.util.concurrent.AbstractExecutorService;
021    import 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     *
032     * @version
033     */
034    public class SynchronousExecutorService extends AbstractExecutorService {
035    
036        private volatile boolean shutdown;
037    
038        public void shutdown() {
039            shutdown = true;
040        }
041    
042        public List<Runnable> shutdownNow() {
043            // not implemented
044            return null;
045        }
046    
047        public boolean isShutdown() {
048            return shutdown;
049        }
050    
051        public boolean isTerminated() {
052            return shutdown;
053        }
054    
055        public boolean awaitTermination(long time, TimeUnit unit) throws InterruptedException {
056            // not implemented
057            return true;
058        }
059    
060        public void execute(Runnable runnable) {
061            // run the task synchronously
062            runnable.run();
063        }
064    
065    }