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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.apache.logging.log4j.Logger;
import org.elasticsearch.action.ActionFuture;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.ActionRequest;
import org.elasticsearch.action.ActionRequestValidationException;
import org.elasticsearch.action.ActionResponse;
import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
import org.elasticsearch.common.component.AbstractComponent;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.tasks.TaskListener;
import org.elasticsearch.tasks.TaskManager;
import org.elasticsearch.threadpool.ThreadPool;
import java.util.concurrent.atomic.AtomicInteger;
import static org.elasticsearch.action.support.PlainActionFuture.newFuture;
public abstract class TransportAction<Request extends ActionRequest, Response extends ActionResponse> extends AbstractComponent {
protected final ThreadPool threadPool;
protected final String actionName;
private final ActionFilter[] filters;
protected final IndexNameExpressionResolver indexNameExpressionResolver;
protected final TaskManager taskManager;
protected TransportAction(Settings settings, String actionName, ThreadPool threadPool, ActionFilters actionFilters,
IndexNameExpressionResolver indexNameExpressionResolver, TaskManager taskManager) {
super(settings);
this.threadPool = threadPool;
this.actionName = actionName;
this.filters = actionFilters.filters();
this.indexNameExpressionResolver = indexNameExpressionResolver;
this.taskManager = taskManager;
}
public final ActionFuture<Response> execute(Request request) {
PlainActionFuture<Response> future = newFuture();
execute(request, future);
return future;
}
/**
* Use this method when the transport action call should result in creation of a new task associated with the call.
*
* This is a typical behavior.
*/
public final Task execute(Request request, ActionListener<Response> listener) {
/*
* While this version of execute could delegate to the TaskListener
* version of execute that'd add yet another layer of wrapping on the
* listener and prevent us from using the listener bare if there isn't a
* task. That just seems like too many objects. Thus the two versions of
* this method.
*/
Task task = taskManager.register("transport", actionName, request);
if (task == null) {
execute(null, request, listener);
} else {
execute(task, request, new ActionListener<Response>() {
@Override
public void onResponse(Response response) {
taskManager.unregister(task);
listener.onResponse(response);
}
@Override
public void onFailure(Exception e) {
taskManager.unregister(task);
listener.onFailure(e);
}
});
}
return task;
}
/**
* Execute the transport action on the local node, returning the {@link Task} used to track its execution and accepting a
* {@link TaskListener} which listens for the completion of the action.
*/
public final Task execute(Request request, TaskListener<Response> listener) {
Task task = taskManager.register("transport", actionName, request);
execute(task, request, new ActionListener<Response>() {
@Override
public void onResponse(Response response) {
if (task != null) {
taskManager.unregister(task);
}
listener.onResponse(task, response);
}
@Override
public void onFailure(Exception e) {
if (task != null) {
taskManager.unregister(task);
}
listener.onFailure(task, e);
}
});
return task;
}
/**
* Use this method when the transport action should continue to run in the context of the current task
*/
public final void execute(Task task, Request request, ActionListener<Response> listener) {
ActionRequestValidationException validationException = request.validate();
if (validationException != null) {
listener.onFailure(validationException);
return;
}
if (task != null && request.getShouldStoreResult()) {
listener = new TaskResultStoringActionListener<>(taskManager, task, listener);
}
RequestFilterChain<Request, Response> requestFilterChain = new RequestFilterChain<>(this, logger);
requestFilterChain.proceed(task, actionName, request, listener);
}
protected void doExecute(Task task, Request request, ActionListener<Response> listener) {
doExecute(request, listener);
}
protected abstract void doExecute(Request request, ActionListener<Response> listener);
private static class RequestFilterChain<Request extends ActionRequest, Response extends ActionResponse>
implements ActionFilterChain<Request, Response> {
private final TransportAction<Request, Response> action;
private final AtomicInteger index = new AtomicInteger();
private final Logger logger;
private RequestFilterChain(TransportAction<Request, Response> action, Logger logger) {
this.action = action;
this.logger = logger;
}
@Override
public void proceed(Task task, String actionName, Request request, ActionListener<Response> listener) {
int i = index.getAndIncrement();
try {
if (i < this.action.filters.length) {
this.action.filters[i].apply(task, actionName, request, listener, this);
} else if (i == this.action.filters.length) {
this.action.doExecute(task, request, listener);
} else {
listener.onFailure(new IllegalStateException("proceed was called too many times"));
}
} catch(Exception e) {
logger.trace("Error during transport action execution.", e);
listener.onFailure(e);
}
}
}
/**
* Wrapper for an action listener that stores the result at the end of the execution
*/
private static class TaskResultStoringActionListener<Response extends ActionResponse> implements ActionListener<Response> {
private final ActionListener<Response> delegate;
private final Task task;
private final TaskManager taskManager;
private TaskResultStoringActionListener(TaskManager taskManager, Task task, ActionListener<Response> delegate) {
this.taskManager = taskManager;
this.task = task;
this.delegate = delegate;
}
@Override
public void onResponse(Response response) {
try {
taskManager.storeResult(task, response, delegate);
} catch (Exception e) {
delegate.onFailure(e);
}
}
@Override
public void onFailure(Exception e) {
try {
taskManager.storeResult(task, e, delegate);
} catch (Exception inner) {
inner.addSuppressed(e);
delegate.onFailure(inner);
}
}
}
}