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* 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.client.Client;
import org.elasticsearch.client.transport.TransportClient;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.common.logging.ESLogger;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.util.concurrent.AbstractRunnable;
import org.elasticsearch.threadpool.ThreadPool;
import java.util.concurrent.Future;
/**
* An action listener that wraps another action listener and threading its execution.
*/
public final class ThreadedActionListener<Response> implements ActionListener<Response> {
/**
* Wrapper that can be used to automatically wrap a listener in a threaded listener if needed.
*/
public static class Wrapper {
private final ESLogger logger;
private final ThreadPool threadPool;
private final boolean threadedListener;
public Wrapper(ESLogger logger, Settings settings, ThreadPool threadPool) {
this.logger = logger;
this.threadPool = threadPool;
// Should the action listener be threaded or not by default. Action listeners are automatically threaded for client
// nodes and transport client in order to make sure client side code is not executed on IO threads.
this.threadedListener = DiscoveryNode.clientNode(settings) || TransportClient.CLIENT_TYPE.equals(settings.get(Client.CLIENT_TYPE_SETTING));
}
public <Response> ActionListener<Response> wrap(ActionListener<Response> listener) {
if (threadedListener == false) {
return listener;
}
// if its a future, the callback is very lightweight (flipping a bit) so no need to wrap it
if (listener instanceof Future) {
return listener;
}
// already threaded...
if (listener instanceof ThreadedActionListener) {
return listener;
}
return new ThreadedActionListener<>(logger, threadPool, ThreadPool.Names.LISTENER, listener);
}
}
private final ESLogger logger;
private final ThreadPool threadPool;
private final String executor;
private final ActionListener<Response> listener;
public ThreadedActionListener(ESLogger logger, ThreadPool threadPool, String executor, ActionListener<Response> listener) {
this.logger = logger;
this.threadPool = threadPool;
this.executor = executor;
this.listener = listener;
}
@Override
public void onResponse(final Response response) {
threadPool.executor(executor).execute(new AbstractRunnable() {
@Override
protected void doRun() throws Exception {
listener.onResponse(response);
}
@Override
public void onFailure(Throwable t) {
listener.onFailure(t);
}
});
}
@Override
public void onFailure(final Throwable e) {
threadPool.executor(executor).execute(new AbstractRunnable() {
@Override
protected void doRun() throws Exception {
listener.onFailure(e);
}
@Override
public void onFailure(Throwable t) {
logger.warn("failed to execute failure callback on [{}], failure [{}]", t, listener, e);
}
});
}
}