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Elasticsearch subproject :server
/*
* 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.transport;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.common.util.concurrent.ConcurrentCollections;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ConcurrentMap;
import java.util.function.BiConsumer;
/**
* Deduplicator for {@link TransportRequest}s that keeps track of {@link TransportRequest}s that should
* not be sent in parallel.
* @param Transport Request Class
*/
public final class TransportRequestDeduplicator {
private final ConcurrentMap requests = ConcurrentCollections.newConcurrentMap();
/**
* Ensures a given request not executed multiple times when another equal request is already in-flight.
* If the request is not yet known to the deduplicator it will invoke the passed callback with an {@link ActionListener}
* that must be completed by the caller when the request completes. Once that listener is completed the request will be removed from
* the deduplicator's internal state. If the request is already known to the deduplicator it will keep
* track of the given listener and invoke it when the listener passed to the callback on first invocation is completed.
* @param request Request to deduplicate
* @param listener Listener to invoke on request completion
* @param callback Callback to be invoked with request and completion listener the first time the request is added to the deduplicator
*/
public void executeOnce(T request, ActionListener listener, BiConsumer> callback) {
ActionListener completionListener = requests.computeIfAbsent(request, CompositeListener::new).addListener(listener);
if (completionListener != null) {
callback.accept(request, completionListener);
}
}
public int size() {
return requests.size();
}
private final class CompositeListener implements ActionListener {
private final List> listeners = new ArrayList<>();
private final T request;
private boolean isNotified;
private Exception failure;
CompositeListener(T request) {
this.request = request;
}
CompositeListener addListener(ActionListener listener) {
synchronized (this) {
if (this.isNotified == false) {
listeners.add(listener);
return listeners.size() == 1 ? this : null;
}
}
if (failure != null) {
listener.onFailure(failure);
} else {
listener.onResponse(null);
}
return null;
}
private void onCompleted(Exception failure) {
synchronized (this) {
this.failure = failure;
this.isNotified = true;
}
try {
if (failure == null) {
ActionListener.onResponse(listeners, null);
} else {
ActionListener.onFailure(listeners, failure);
}
} finally {
requests.remove(request);
}
}
@Override
public void onResponse(final Void aVoid) {
onCompleted(null);
}
@Override
public void onFailure(Exception failure) {
onCompleted(failure);
}
}
}