/**
*
* 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.airavata.workflow.engine.concurrent;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
* Used to run jobs that need to be started after a predicate is
*
* @author Chathura Herath
*/
public class PredicatedTaskRunner {
protected volatile ConcurrentLinkedQueue<PredicatedExecutable> jobQueue = new ConcurrentLinkedQueue<PredicatedExecutable>();
protected ExecutorService threadPool;
protected volatile boolean stop = false;
private static final Logger logger = LoggerFactory.getLogger(PredicatedTaskRunner.class);
public PredicatedTaskRunner(int numberOfThreads) {
this.threadPool = Executors.newFixedThreadPool(numberOfThreads);
addIdleTask();
startCheckThread();
}
private void addIdleTask() {
PredicatedExecutable sleepTask = new PredicatedExecutable() {
@Override
public void run() {
synchronized (jobQueue) {
if (jobQueue.size() == 1) {
try {
jobQueue.wait();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
} else if (allTasksAreWaiting(jobQueue)) {
try {
Thread.sleep(50);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
}
private boolean allTasksAreWaiting(
ConcurrentLinkedQueue<PredicatedExecutable> jobQueue) {
for (PredicatedExecutable predicatedExecutable : jobQueue) {
if (predicatedExecutable.isReady()) {
return false;
}
}
return true;
}
@Override
public boolean isReady() {
// TODO Auto-generated method stub
return true;
}
};
this.jobQueue.add(sleepTask);
}
private void startCheckThread() {
new Thread(new Runnable() {
@Override
public void run() {
while (!stop) {
try {
synchronized (jobQueue) {
while(jobQueue.size() == 0 || allTasksAreWaiting(jobQueue)){
jobQueue.wait(50);
}
}
PredicatedExecutable job = jobQueue.remove();
if (job.isReady()) {
// remove from front and execute and you are done
threadPool.execute(job);
} else {
// add to end if not ready to run
jobQueue.add(job);
}
} catch (Throwable e) {
// we go on no matter what
logger.error(e.getMessage(), e);
}
}
}
}).start();
}
private boolean allTasksAreWaiting(
ConcurrentLinkedQueue<PredicatedExecutable> jobQueue) {
for (PredicatedExecutable predicatedExecutable : jobQueue) {
if (predicatedExecutable.isReady()) {
return false;
}
}
return true;
}
public void scedule(PredicatedExecutable job) {
synchronized (jobQueue) {
this.jobQueue.add(job);
this.jobQueue.notifyAll();
}
}
public void shutDown() {
this.threadPool.shutdown();
this.stop = true;
}
}