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.activemq.thread;
018
019import org.apache.activemq.util.MDCHelper;
020import org.slf4j.MDC;
021
022import java.util.Map;
023import java.util.concurrent.Executor;
024
025/**
026 * 
027 */
028public class DeterministicTaskRunner implements TaskRunner {
029
030    private final Executor executor;
031    private final Task task;
032    private final Runnable runable;
033    private boolean shutdown;    
034    
035    /**Constructor
036     * @param executor
037     * @param task
038     */
039    public DeterministicTaskRunner(Executor executor, Task task) {
040        this.executor = executor;
041        this.task = task;
042        final Map context = MDCHelper.getCopyOfContextMap();
043        this.runable = new Runnable() {
044            public void run() {
045                Thread.currentThread();
046                if (context != null) {
047                    MDCHelper.setContextMap(context);
048                }
049                runTask();
050            }
051        };
052    }
053
054    /**
055     * We Expect MANY wakeup calls on the same TaskRunner - but each
056     * needs to run
057     */
058    public void wakeup() throws InterruptedException {
059        synchronized (runable) {
060
061            if (shutdown) {
062                return;
063            }
064            executor.execute(runable);
065
066        }
067    }
068
069    /**
070     * shut down the task
071     * 
072     * @throws InterruptedException
073     */
074    public void shutdown(long timeout) throws InterruptedException {
075        synchronized (runable) {
076            shutdown = true;
077        }
078    }
079
080    public void shutdown() throws InterruptedException {
081        shutdown(0);
082    }
083
084    final void runTask() {
085
086        synchronized (runable) {
087            if (shutdown) {
088                runable.notifyAll();
089                return;
090            }
091        }
092        task.iterate();
093    }
094}