/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.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 it's results to another listener once
* it has received one or more failures or N results. 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<T> implements ActionListener<T> {
private final CountDown countDown;
private final AtomicInteger pos = new AtomicInteger();
private final AtomicArray<T> roles;
private final ActionListener<Collection<T>> delegate;
private final Collection<T> defaults;
private final AtomicReference<Exception> failure = new AtomicReference<>();
/**
* Creates a new listener
* @param delegate the delegate listener
* @param groupSize the group size
*/
public GroupedActionListener(ActionListener<Collection<T>> delegate, int groupSize,
Collection<T> defaults) {
roles = new AtomicArray<>(groupSize);
countDown = new CountDown(groupSize);
this.delegate = delegate;
this.defaults = defaults;
}
@Override
public void onResponse(T element) {
roles.set(pos.incrementAndGet() - 1, element);
if (countDown.countDown()) {
if (failure.get() != null) {
delegate.onFailure(failure.get());
} else {
List<T> collect = this.roles.asList();
collect.addAll(defaults);
delegate.onResponse(Collections.unmodifiableList(collect));
}
}
}
@Override
public void onFailure(Exception e) {
if (failure.compareAndSet(null, e) == false) {
failure.get().addSuppressed(e);
}
if (countDown.countDown()) {
delegate.onFailure(failure.get());
}
}
}