/**
* Copyright 2013 BlackLocus
*
* Licensed 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 com.blacklocus.qs.worker.util.task;
import com.blacklocus.misc.ExceptingRunnable;
import com.blacklocus.misc.InfiniteRunnable;
import com.blacklocus.qs.worker.QSTaskService;
import com.blacklocus.qs.worker.model.QSTaskModel;
import com.github.rholder.moar.concurrent.QueueingStrategy;
import java.util.Collection;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.SynchronousQueue;
/**
* @author Jason Dunkelberger (dirkraft)
*/
public class ThreadedFIFOQSTaskService implements QSTaskService {
private final QueueingStrategy<QSTaskModel> queueingStrategy;
// This fair=true is essentially what makes it round-robin.
private final SynchronousQueue<QSTaskModel> transferQueue = new SynchronousQueue<QSTaskModel>(true);
private final Map<QSTaskModel, QSTaskService> taskServices = new ConcurrentHashMap<QSTaskModel, QSTaskService>();
public ThreadedFIFOQSTaskService(final QueueingStrategy<QSTaskModel> queueingStrategy, Collection<QSTaskService> taskServices) {
this.queueingStrategy = queueingStrategy;
ExecutorService executorService = Executors.newCachedThreadPool();
for (final QSTaskService taskService : taskServices) {
executorService.submit(new InfiniteRunnable(new TaskTransferRunnable(taskService)));
}
}
@Override
public void putTask(QSTaskModel task) {
throw new RuntimeException("ThreadedFIFOQSTaskService is purposed for retrieving tasks and cannot " +
"determine which constituent Task Service should be used to place a new task.");
}
@Override
public QSTaskModel getAvailableTask() {
try {
return transferQueue.take();
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
@Override
public void resetTask(QSTaskModel task) {
taskServices.remove(task).resetTask(task);
}
@Override
public void closeTask(QSTaskModel task) {
taskServices.remove(task).closeTask(task);
}
class TaskTransferRunnable extends ExceptingRunnable {
final QSTaskService taskService;
TaskTransferRunnable(QSTaskService taskService) {
this.taskService = taskService;
}
@Override
protected void go() throws Exception {
// If the heap is filling up, this should block for a bit. queueStrategy.on*Remove called when
// task processing completes in the WorkerQueueItemHandler.
queueingStrategy.onBeforeAdd(null);
QSTaskModel task = taskService.getAvailableTask();
taskServices.put(task, taskService);
transferQueue.put(task);
queueingStrategy.onAfterAdd();
}
}
}