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/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.action.support;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.common.util.concurrent.AtomicArray;
import org.elasticsearch.common.util.concurrent.CountDown;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
/**
* An action listener that delegates its results to another listener once
* it has received N results (either successes or failures). This allows synchronous
* tasks to be forked off in a loop with the same listener and respond to a
* higher level listener once all tasks responded.
*/
public final class GroupedActionListener extends ActionListener.Delegating> {
private final CountDown countDown;
private final AtomicInteger pos = new AtomicInteger();
private final AtomicArray results;
private final AtomicReference failure = new AtomicReference<>();
/**
* Creates a new listener
* @param delegate the delegate listener
* @param groupSize the group size
*/
public GroupedActionListener(ActionListener> delegate, int groupSize) {
super(delegate);
if (groupSize <= 0) {
assert false : "illegal group size [" + groupSize + "]";
throw new IllegalArgumentException("groupSize must be greater than 0 but was " + groupSize);
}
results = new AtomicArray<>(groupSize);
countDown = new CountDown(groupSize);
}
@Override
public void onResponse(T element) {
results.setOnce(pos.incrementAndGet() - 1, element);
if (countDown.countDown()) {
if (failure.get() != null) {
super.onFailure(failure.get());
} else {
List collect = this.results.asList();
delegate.onResponse(Collections.unmodifiableList(collect));
}
}
}
@Override
public void onFailure(Exception e) {
if (failure.compareAndSet(null, e) == false) {
failure.accumulateAndGet(e, (current, update) -> {
// we have to avoid self-suppression!
if (update != current) {
current.addSuppressed(update);
}
return current;
});
}
if (countDown.countDown()) {
super.onFailure(failure.get());
}
}
}