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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.tuscany.sca.core.work.impl;
import java.util.Collection;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.ThreadFactory;
import org.apache.tuscany.sca.work.WorkSchedulerException;
/**
* A thread-pool based implementation for the JSR-237 work manager.
* <p/>
* <p/>
* This implementation supports only local work.
* <p/>
* TODO Elaborate the implementation. </p>
*
* @version $Rev$ $Date$
*/
public class ThreadPoolWorkManager {
// Map of work items currently handled by the work manager
private Map<WorkItem, WorkListener> workItems = new ConcurrentHashMap<WorkItem, WorkListener>();
// Thread-pool
protected ExecutorService executor;
/**
* Initializes the thread-pool.
*
* @param threadPoolSize Thread-pool size. If the size <1, then a cached pool is created
*/
public ThreadPoolWorkManager(int threadPoolSize) {
ThreadFactory factory = new ThreadFactory() {
public Thread newThread(Runnable r) {
Thread thread = new Thread(r);
thread.setDaemon(true);
return thread;
}
};
if (threadPoolSize <= 0) {
// Creates a new Executor, use a custom ThreadFactory that
// creates daemon threads.
executor = Executors.newCachedThreadPool(factory);
} else {
executor = Executors.newFixedThreadPool(threadPoolSize, factory);
}
}
/**
* Schedules a unit of work asynchronously.
*
* @param work Work that needs to be scheduled.
* @return Work Work item representing the asynchronous work
*/
public WorkItem schedule(Work work) throws IllegalArgumentException {
return schedule(work, null);
}
/**
* Schedules a unit of work asynchronously.
*
* @param work Work that needs to be scheduled.
* @param workListener Work listener for callbacks.
* @return Work Work item representing the asynchronous work
*/
public WorkItem schedule(Work work, WorkListener workListener) throws IllegalArgumentException {
WorkItem workItem = new WorkItem(UUID.randomUUID().toString(), work);
if (workListener != null) {
workItems.put(workItem, workListener);
}
workAccepted(workItem, work);
if (scheduleWork(work, workItem)) {
return workItem;
} else {
workItem.setStatus(WorkEvent.WORK_REJECTED);
if (workListener != null) {
workListener.workRejected(new WorkEvent(workItem));
}
throw new IllegalArgumentException("Unable to schedule work");
}
}
/**
* Wait for all the specified units of work to finish.
*
* @param works Units of the work that need to finish.
* @param timeout Timeout for waiting for the units of work to finish.
*/
public boolean waitForAll(Collection works, long timeout) {
throw new UnsupportedOperationException("waitForAll not supported");
}
/**
* Wait for any of the specified units of work to finish.
*
* @param works Units of the work that need to finish.
* @param timeout Timeout for waiting for the units of work to finish.
*/
public Collection waitForAny(Collection works, long timeout) {
throw new UnsupportedOperationException("waitForAny not supported");
}
/**
* Method provided for subclasses to indicate a work acceptance.
*
* @param workItem Work item representing the work that was accepted.
* @param work Work that was accepted.
*/
private void workAccepted(final WorkItem workItem, final Work work) {
WorkListener listener = workItems.get(workItem);
if (listener != null) {
workItem.setStatus(WorkEvent.WORK_ACCEPTED);
WorkEvent event = new WorkEvent(workItem);
listener.workAccepted(event);
}
}
/*
* Method to indicate a work start.
*/
private void workStarted(final WorkItem workItem, final Work work) {
WorkListener listener = workItems.get(workItem);
if (listener != null) {
workItem.setStatus(WorkEvent.WORK_STARTED);
WorkEvent event = new WorkEvent(workItem);
listener.workStarted(event);
}
}
/*
* Method to indicate a work completion.
*/
private void workCompleted(final WorkItem workItem, final Work work) {
workCompleted(workItem, work, null);
}
/*
* Method to indicate a work completion.
*/
private void workCompleted(final WorkItem workItem, final Work work, final WorkSchedulerException exception) {
WorkListener listener = workItems.get(workItem);
if (listener != null) {
workItem.setStatus(WorkEvent.WORK_COMPLETED);
workItem.setResult(work);
workItem.setException(exception);
WorkEvent event = new WorkEvent(workItem);
listener.workCompleted(event);
workItems.remove(workItem);
}
}
/*
* Schedules the work using the ThreadPool.
*/
private boolean scheduleWork(final Work work, final WorkItem workItem) {
try {
executor.execute(new DecoratingWork(workItem, work));
return true;
} catch (RejectedExecutionException ex) {
return false;
}
}
/*
* Class that decorates the original worker so that it can get callbacks when work is done.
*/
private final class DecoratingWork implements Runnable {
// Work item for this work.
private WorkItem workItem;
// The original work.
private Work decoratedWork;
/*
* Initializes the work item and underlying work.
*/
private DecoratingWork(final WorkItem workItem, final Work decoratedWork) {
this.workItem = workItem;
this.decoratedWork = decoratedWork;
}
/*
* Overrides the run method.
*/
public void run() {
workStarted(workItem, decoratedWork);
try {
decoratedWork.run();
workCompleted(workItem, decoratedWork);
} catch (Throwable th) {
workCompleted(workItem, decoratedWork, new WorkSchedulerException(th.getMessage(), th));
}
}
}
public void destroy() {
executor.shutdown();
}
public ExecutorService getExecutorService() {
return executor;
}
}
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