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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
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******************************************************************************/
package org.apache.sling.scripting.sightly.js.impl.loop;
import java.util.LinkedList;
import java.util.Queue;
import org.apache.sling.scripting.sightly.SightlyException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Simulates an event loop for the Rhino JS engine.
*/
public class EventLoop {
private static final Logger log = LoggerFactory.getLogger(EventLoop.class);
private Queue<Task> taskQueue = new LinkedList<Task>();
private boolean isRunning;
/**
* Add a task to the queue. If the queue is empty, start running tasks. If it
* isn't empty, continue running the available tasks
* @param task the task to be added
*/
public void schedule(Task task) {
taskQueue.offer(task);
run();
}
private void run() {
if (isRunning) {
return;
}
isRunning = true;
try {
// Holds the first exception encountered. If there is such a first exception, it will be
// rethrown
Exception thrownException = null;
while (!taskQueue.isEmpty()) {
Task task = taskQueue.poll();
try {
task.run();
} catch (Exception e) {
if (thrownException == null) {
thrownException = e; //first exception
} else {
log.error("Additional error occurred while running JS script: ", e);
}
}
}
if (thrownException != null) {
throw new SightlyException(thrownException);
}
} finally {
isRunning = false;
}
}
}