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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.single.shard;
import org.apache.logging.log4j.message.ParameterizedMessage;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.ActionResponse;
import org.elasticsearch.action.NoShardAvailableActionException;
import org.elasticsearch.action.support.ActionFilters;
import org.elasticsearch.action.support.TransportAction;
import org.elasticsearch.action.support.TransportActions;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.block.ClusterBlockException;
import org.elasticsearch.cluster.block.ClusterBlockLevel;
import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.node.DiscoveryNodes;
import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.cluster.routing.ShardsIterator;
import org.elasticsearch.cluster.service.ClusterService;
import org.elasticsearch.common.Nullable;
import org.elasticsearch.common.logging.LoggerMessageFormat;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.index.shard.ShardId;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.transport.TransportChannel;
import org.elasticsearch.transport.TransportException;
import org.elasticsearch.transport.TransportRequestHandler;
import org.elasticsearch.transport.TransportResponseHandler;
import org.elasticsearch.transport.TransportService;
import java.io.IOException;
import java.util.function.Supplier;
import static org.elasticsearch.action.support.TransportActions.isShardNotAvailableException;
/**
* A base class for operations that need to perform a read operation on a single shard copy. If the operation fails,
* the read operation can be performed on other shard copies. Concrete implementations can provide their own list
* of candidate shards to try the read operation on.
*/
public abstract class TransportSingleShardAction<Request extends SingleShardRequest<Request>, Response extends ActionResponse> extends TransportAction<Request, Response> {
protected final ClusterService clusterService;
protected final TransportService transportService;
final String transportShardAction;
final String executor;
protected TransportSingleShardAction(Settings settings, String actionName, ThreadPool threadPool, ClusterService clusterService,
TransportService transportService, ActionFilters actionFilters, IndexNameExpressionResolver indexNameExpressionResolver,
Supplier<Request> request, String executor) {
super(settings, actionName, threadPool, actionFilters, indexNameExpressionResolver, transportService.getTaskManager());
this.clusterService = clusterService;
this.transportService = transportService;
this.transportShardAction = actionName + "[s]";
this.executor = executor;
if (!isSubAction()) {
transportService.registerRequestHandler(actionName, request, ThreadPool.Names.SAME, new TransportHandler());
}
transportService.registerRequestHandler(transportShardAction, request, executor, new ShardTransportHandler());
}
/**
* Tells whether the action is a main one or a subaction. Used to decide whether we need to register
* the main transport handler. In fact if the action is a subaction, its execute method
* will be called locally to its parent action.
*/
protected boolean isSubAction() {
return false;
}
@Override
protected void doExecute(Request request, ActionListener<Response> listener) {
new AsyncSingleAction(request, listener).start();
}
protected abstract Response shardOperation(Request request, ShardId shardId) throws IOException;
protected abstract Response newResponse();
protected abstract boolean resolveIndex(Request request);
protected ClusterBlockException checkGlobalBlock(ClusterState state) {
return state.blocks().globalBlockedException(ClusterBlockLevel.READ);
}
protected ClusterBlockException checkRequestBlock(ClusterState state, InternalRequest request) {
return state.blocks().indexBlockedException(ClusterBlockLevel.READ, request.concreteIndex());
}
protected void resolveRequest(ClusterState state, InternalRequest request) {
}
/**
* Returns the candidate shards to execute the operation on or <code>null</code> the execute
* the operation locally (the node that received the request)
*/
@Nullable
protected abstract ShardsIterator shards(ClusterState state, InternalRequest request);
class AsyncSingleAction {
private final ActionListener<Response> listener;
private final ShardsIterator shardIt;
private final InternalRequest internalRequest;
private final DiscoveryNodes nodes;
private volatile Exception lastFailure;
private AsyncSingleAction(Request request, ActionListener<Response> listener) {
this.listener = listener;
ClusterState clusterState = clusterService.state();
if (logger.isTraceEnabled()) {
logger.trace("executing [{}] based on cluster state version [{}]", request, clusterState.version());
}
nodes = clusterState.nodes();
ClusterBlockException blockException = checkGlobalBlock(clusterState);
if (blockException != null) {
throw blockException;
}
String concreteSingleIndex;
if (resolveIndex(request)) {
concreteSingleIndex = indexNameExpressionResolver.concreteSingleIndex(clusterState, request).getName();
} else {
concreteSingleIndex = request.index();
}
this.internalRequest = new InternalRequest(request, concreteSingleIndex);
resolveRequest(clusterState, internalRequest);
blockException = checkRequestBlock(clusterState, internalRequest);
if (blockException != null) {
throw blockException;
}
this.shardIt = shards(clusterState, internalRequest);
}
public void start() {
if (shardIt == null) {
// just execute it on the local node
transportService.sendRequest(clusterService.localNode(), transportShardAction, internalRequest.request(), new TransportResponseHandler<Response>() {
@Override
public Response newInstance() {
return newResponse();
}
@Override
public String executor() {
return ThreadPool.Names.SAME;
}
@Override
public void handleResponse(final Response response) {
listener.onResponse(response);
}
@Override
public void handleException(TransportException exp) {
listener.onFailure(exp);
}
});
} else {
perform(null);
}
}
private void onFailure(ShardRouting shardRouting, Exception e) {
if (logger.isTraceEnabled() && e != null) {
logger.trace(
(org.apache.logging.log4j.util.Supplier<?>)
() -> new ParameterizedMessage("{}: failed to execute [{}]", shardRouting, internalRequest.request()), e);
}
perform(e);
}
private void perform(@Nullable final Exception currentFailure) {
Exception lastFailure = this.lastFailure;
if (lastFailure == null || TransportActions.isReadOverrideException(currentFailure)) {
lastFailure = currentFailure;
this.lastFailure = currentFailure;
}
final ShardRouting shardRouting = shardIt.nextOrNull();
if (shardRouting == null) {
Exception failure = lastFailure;
if (failure == null || isShardNotAvailableException(failure)) {
failure = new NoShardAvailableActionException(null, LoggerMessageFormat.format("No shard available for [{}]", internalRequest.request()), failure);
} else {
if (logger.isDebugEnabled()) {
logger.debug(
(org.apache.logging.log4j.util.Supplier<?>)
() -> new ParameterizedMessage("{}: failed to execute [{}]", null, internalRequest.request()), failure);
}
}
listener.onFailure(failure);
return;
}
DiscoveryNode node = nodes.get(shardRouting.currentNodeId());
if (node == null) {
onFailure(shardRouting, new NoShardAvailableActionException(shardRouting.shardId()));
} else {
internalRequest.request().internalShardId = shardRouting.shardId();
if (logger.isTraceEnabled()) {
logger.trace(
"sending request [{}] to shard [{}] on node [{}]",
internalRequest.request(),
internalRequest.request().internalShardId,
node
);
}
transportService.sendRequest(node, transportShardAction, internalRequest.request(), new TransportResponseHandler<Response>() {
@Override
public Response newInstance() {
return newResponse();
}
@Override
public String executor() {
return ThreadPool.Names.SAME;
}
@Override
public void handleResponse(final Response response) {
listener.onResponse(response);
}
@Override
public void handleException(TransportException exp) {
onFailure(shardRouting, exp);
}
});
}
}
}
private class TransportHandler implements TransportRequestHandler<Request> {
@Override
public void messageReceived(Request request, final TransportChannel channel) throws Exception {
// if we have a local operation, execute it on a thread since we don't spawn
request.operationThreaded(true);
execute(request, new ActionListener<Response>() {
@Override
public void onResponse(Response result) {
try {
channel.sendResponse(result);
} catch (Exception e) {
onFailure(e);
}
}
@Override
public void onFailure(Exception e) {
try {
channel.sendResponse(e);
} catch (Exception e1) {
logger.warn("failed to send response for get", e1);
}
}
});
}
}
private class ShardTransportHandler implements TransportRequestHandler<Request> {
@Override
public void messageReceived(final Request request, final TransportChannel channel) throws Exception {
if (logger.isTraceEnabled()) {
logger.trace("executing [{}] on shard [{}]", request, request.internalShardId);
}
Response response = shardOperation(request, request.internalShardId);
channel.sendResponse(response);
}
}
/**
* Internal request class that gets built on each node. Holds the original request plus additional info.
*/
protected class InternalRequest {
final Request request;
final String concreteIndex;
InternalRequest(Request request, String concreteIndex) {
this.request = request;
this.concreteIndex = concreteIndex;
}
public Request request() {
return request;
}
public String concreteIndex() {
return concreteIndex;
}
}
}