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