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/*******************************************************************************
* Copyright (c) quickfixengine.org All rights reserved.
*
* This file is part of the QuickFIX FIX Engine
*
* This file may be distributed under the terms of the quickfixengine.org
* license as defined by quickfixengine.org and appearing in the file
* LICENSE included in the packaging of this file.
*
* This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING
* THE WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE.
*
* See http://www.quickfixengine.org/LICENSE for licensing information.
*
* Contact [email protected] if any conditions of this licensing
* are not clear to you.
******************************************************************************/
package quickfix.mina;
import java.util.AbstractCollection;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;
import java.util.function.Consumer;
import java.util.function.Function;
/**
* A blocking queue wrapper implementing watermarks-based back pressure propagation
* from the queue sink to one or more logical sources.
*
* @param payload type
* @param logical source key type
*
* @author Vladimir Lysyy (mrbald@github)
*/
public class WatermarkTracker implements QueueTracker {
private final BlockingQueue queue;
private final long lowerWatermark;
private final long upperWatermark;
private final Consumer onLowerWatermarkCrossed;
private final Consumer onUpperWatermarkCrossed;
private final Function classifier;
private final Function trackerSupplier;
class StreamTracker {
private final S key;
long counter = 0;
private boolean suspended = false;
StreamTracker(S key) {
this.key = key;
}
synchronized void incoming(int n) {
if ((counter += n) >= upperWatermark && !suspended) {
suspended = true;
onUpperWatermarkCrossed.accept(key);
}
}
synchronized void outgoing(int n) {
if ((counter -= n) == lowerWatermark && suspended) {
suspended = false;
onLowerWatermarkCrossed.accept(key);
}
}
synchronized boolean isSuspended() {
return suspended;
}
}
static WatermarkTracker newMono(
BlockingQueue queue,
long lowerWatermark, long upperWatermark,
Runnable onLowerWatermarkCrossed, Runnable onUpperWatermarkCrossed) {
return new WatermarkTracker<>(queue, lowerWatermark, upperWatermark, onLowerWatermarkCrossed, onUpperWatermarkCrossed);
}
static WatermarkTracker newMulti(
BlockingQueue queue,
long lowerWatermark, long upperWatermark,
Function classifier,
Consumer onLowerWatermarkCrossed, Consumer onUpperWatermarkCrossed) {
return new WatermarkTracker<>(queue, lowerWatermark, upperWatermark, classifier, onLowerWatermarkCrossed, onUpperWatermarkCrossed);
}
private WatermarkTracker(
BlockingQueue queue,
long lowerWatermark, long upperWatermark,
Function classifier,
Consumer onLowerWatermarkCrossed, Consumer onUpperWatermarkCrossed) {
this.queue = queue;
this.lowerWatermark = lowerWatermark;
this.upperWatermark = upperWatermark;
this.classifier = classifier;
this.onLowerWatermarkCrossed = onLowerWatermarkCrossed;
this.onUpperWatermarkCrossed = onUpperWatermarkCrossed;
final Map trackerMap = new ConcurrentHashMap<>();
this.trackerSupplier = key -> trackerMap.computeIfAbsent(key, StreamTracker::new);
}
private WatermarkTracker(
BlockingQueue queue,
long lowerWatermark, long upperWatermark,
Runnable onLowerWatermarkCrossed, Runnable onUpperWatermarkCrossed) {
this.queue = queue;
this.lowerWatermark = lowerWatermark;
this.upperWatermark = upperWatermark;
this.classifier = x -> null;
this.onLowerWatermarkCrossed = x -> onLowerWatermarkCrossed.run();
this.onUpperWatermarkCrossed = x -> onUpperWatermarkCrossed.run();
final StreamTracker streamTracker = new StreamTracker(null);
this.trackerSupplier = key -> streamTracker;
}
@Override
public void put(E e) throws InterruptedException {
queue.put(e);
trackerForPayload(e).incoming(1);
}
@Override
public E poll(long timeout, TimeUnit unit) throws InterruptedException {
final E e = queue.poll(timeout, unit);
if (e != null) {
trackerForPayload(e).outgoing(1);
}
return e;
}
@Override
public int drainTo(Collection collection) {
return queue.drainTo(new AbstractCollection() {
@Override public Iterator iterator() { throw new UnsupportedOperationException(); }
@Override public int size() { throw new UnsupportedOperationException(); }
public boolean add(E e) {
final boolean added = collection.add(e);
if (added) {
trackerForPayload(e).outgoing(1);
}
return added;
}
});
}
public boolean isSuspended(S key) {
return trackerForStream(key).isSuspended();
}
public boolean isSuspended() {
return isSuspended(null);
}
StreamTracker trackerForPayload(E e) {
return trackerForStream(classifier.apply(e));
}
StreamTracker trackerForStream(S s) {
return trackerSupplier.apply(s);
}
}