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/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.action.explain;
import org.apache.lucene.search.Explanation;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.support.ActionFilters;
import org.elasticsearch.action.support.single.shard.TransportSingleShardAction;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
import org.elasticsearch.cluster.routing.ShardIterator;
import org.elasticsearch.cluster.service.ClusterService;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.io.stream.Writeable;
import org.elasticsearch.core.Releasables;
import org.elasticsearch.index.IndexService;
import org.elasticsearch.index.engine.Engine;
import org.elasticsearch.index.get.GetResult;
import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.index.query.Rewriteable;
import org.elasticsearch.index.shard.IndexShard;
import org.elasticsearch.index.shard.ShardId;
import org.elasticsearch.search.SearchService;
import org.elasticsearch.search.internal.AliasFilter;
import org.elasticsearch.search.internal.SearchContext;
import org.elasticsearch.search.internal.ShardSearchRequest;
import org.elasticsearch.search.rescore.RescoreContext;
import org.elasticsearch.search.rescore.Rescorer;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.transport.TransportService;
import java.io.IOException;
import java.util.Set;
import java.util.function.LongSupplier;
/**
* Explain transport action. Computes the explain on the targeted shard.
*/
// TODO: AggregatedDfs. Currently the idf can be different then when executing a normal search with explain.
public class TransportExplainAction extends TransportSingleShardAction {
private final SearchService searchService;
@Inject
public TransportExplainAction(
ThreadPool threadPool,
ClusterService clusterService,
TransportService transportService,
SearchService searchService,
ActionFilters actionFilters,
IndexNameExpressionResolver indexNameExpressionResolver
) {
super(
ExplainAction.NAME,
threadPool,
clusterService,
transportService,
actionFilters,
indexNameExpressionResolver,
ExplainRequest::new,
ThreadPool.Names.GET
);
this.searchService = searchService;
}
@Override
protected void doExecute(Task task, ExplainRequest request, ActionListener listener) {
request.nowInMillis = System.currentTimeMillis();
ActionListener rewriteListener = ActionListener.wrap(rewrittenQuery -> {
request.query(rewrittenQuery);
super.doExecute(task, request, listener);
}, listener::onFailure);
assert request.query() != null;
LongSupplier timeProvider = () -> request.nowInMillis;
Rewriteable.rewriteAndFetch(request.query(), searchService.getRewriteContext(timeProvider), rewriteListener);
}
@Override
protected boolean resolveIndex(ExplainRequest request) {
return true;
}
@Override
protected void resolveRequest(ClusterState state, InternalRequest request) {
final Set indicesAndAliases = indexNameExpressionResolver.resolveExpressions(state, request.request().index());
final AliasFilter aliasFilter = searchService.buildAliasFilter(state, request.concreteIndex(), indicesAndAliases);
request.request().filteringAlias(aliasFilter);
}
@Override
protected void asyncShardOperation(ExplainRequest request, ShardId shardId, ActionListener listener)
throws IOException {
IndexService indexService = searchService.getIndicesService().indexServiceSafe(shardId.getIndex());
IndexShard indexShard = indexService.getShard(shardId.id());
indexShard.awaitShardSearchActive(b -> {
try {
super.asyncShardOperation(request, shardId, listener);
} catch (Exception ex) {
listener.onFailure(ex);
}
});
}
@Override
protected ExplainResponse shardOperation(ExplainRequest request, ShardId shardId) throws IOException {
ShardSearchRequest shardSearchLocalRequest = new ShardSearchRequest(shardId, request.nowInMillis, request.filteringAlias());
SearchContext context = searchService.createSearchContext(shardSearchLocalRequest, SearchService.NO_TIMEOUT);
Engine.GetResult result = null;
try {
// No need to check the type, IndexShard#get does it for us
result = context.indexShard().get(new Engine.Get(false, false, request.id()));
if (result.exists() == false) {
return new ExplainResponse(shardId.getIndexName(), request.id(), false);
}
context.parsedQuery(context.getSearchExecutionContext().toQuery(request.query()));
context.preProcess();
int topLevelDocId = result.docIdAndVersion().docId + result.docIdAndVersion().docBase;
Explanation explanation = context.searcher().explain(context.rewrittenQuery(), topLevelDocId);
for (RescoreContext ctx : context.rescore()) {
Rescorer rescorer = ctx.rescorer();
explanation = rescorer.explain(topLevelDocId, context.searcher(), ctx, explanation);
}
if (request.storedFields() != null || (request.fetchSourceContext() != null && request.fetchSourceContext().fetchSource())) {
// Advantage is that we're not opening a second searcher to retrieve the _source. Also
// because we are working in the same searcher in engineGetResult we can be sure that a
// doc isn't deleted between the initial get and this call.
GetResult getResult = context.indexShard()
.getService()
.get(result, request.id(), request.storedFields(), request.fetchSourceContext());
return new ExplainResponse(shardId.getIndexName(), request.id(), true, explanation, getResult);
} else {
return new ExplainResponse(shardId.getIndexName(), request.id(), true, explanation);
}
} catch (IOException e) {
throw new ElasticsearchException("Could not explain", e);
} finally {
Releasables.close(result, context);
}
}
@Override
protected Writeable.Reader getResponseReader() {
return ExplainResponse::new;
}
@Override
protected ShardIterator shards(ClusterState state, InternalRequest request) {
return clusterService.operationRouting()
.getShards(
clusterService.state(),
request.concreteIndex(),
request.request().id(),
request.request().routing(),
request.request().preference()
);
}
@Override
protected String getExecutor(ExplainRequest request, ShardId shardId) {
IndexService indexService = searchService.getIndicesService().indexServiceSafe(shardId.getIndex());
return indexService.getIndexSettings().isSearchThrottled()
? ThreadPool.Names.SEARCH_THROTTLED
: super.getExecutor(request, shardId);
}
}