org.openqa.selenium.server.SingleEntryAsyncQueue Maven / Gradle / Ivy
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// 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
//
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package org.openqa.selenium.server;
import static java.lang.System.currentTimeMillis;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import java.util.logging.Logger;
/**
*
* Holds the command to be next run in the browser
*
* This class uses reentrant locks in order to allow the same thread to populate the queue as is
* waiting for it, which is what currently happens on during browser startup.
*
* @author Jennifer Bevan
* @version $Revision: 734 $
*/
public class SingleEntryAsyncQueue {
public static final long MILLISECONDS = 1000L;
private static final Logger log = Logger.getLogger(SingleEntryAsyncQueue.class.getName());
private final AtomicReference poisonData;
private final long timeoutInSeconds;
private final ArrayBlockingQueue holder;
public SingleEntryAsyncQueue(long timeoutInSecs) {
timeoutInSeconds = timeoutInSecs;
holder = new ArrayBlockingQueue<>(1);
poisonData = new AtomicReference<>();
}
public long getTimeoutInSeconds() {
return timeoutInSeconds;
}
protected void setPoison(T poisonInstance) {
poisonData.set(poisonInstance);
}
protected boolean isPoison(T poisonSample) {
T poison = poisonData.get();
return null != poison && poison.equals(poisonSample);
}
protected T pollToGetContentUntilTimeout() {
T result = holder.poll(); // in case it's already there
if (null != result) {
log.fine("data was waiting: " + result);
return result;
}
if (timeoutInSeconds <= 0) {
return null;
}
long deadline = currentTimeMillis() + (timeoutInSeconds * MILLISECONDS);
for (long now = currentTimeMillis(); now < deadline; now = currentTimeMillis()) {
try {
log.fine("waiting for data for at most " + timeoutInSeconds + " more s");
result = holder.poll(deadline - now, TimeUnit.MILLISECONDS);
log.fine("data from polling: " + result);
return result;
} catch (InterruptedException ie) {
log.fine("was interrupted; resuming wait");
continue;
}
}
return null;
}
protected boolean putContent(T thing) {
final boolean result;
log.fine("putting command: " + thing);
result = holder.offer(thing);
log.fine("..command put?: " + result);
return result;
}
protected boolean isEmpty() {
return (0 == holder.size());
}
protected T peek() {
return holder.peek();
}
/**
* Clears the contents of the holder (if any) and also feeds 'poison' data a pending listener (if
* any);
*
* @return true if poison was set and sent to any listeners.
*/
protected boolean poisonPollers() {
if (null == poisonData.get()) {
holder.clear();
return false;
}
// offer poison content. If something is already there,
// then the next listener will already have something to get.
putContent(poisonData.get());
return true;
}
}