org.elasticsearch.search.fetch.explain.ExplainFetchSubPhase Maven / Gradle / Ivy

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/*
 * Licensed to Elastic Search and Shay Banon under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. Elastic Search 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.search.fetch.explain;

import com.google.common.collect.ImmutableMap;

import org.apache.lucene.search.Explanation;
import org.elasticsearch.ElasticSearchException;
import org.elasticsearch.search.SearchParseElement;
import org.elasticsearch.search.fetch.FetchPhaseExecutionException;
import org.elasticsearch.search.fetch.FetchSubPhase;
import org.elasticsearch.search.internal.InternalSearchHit;
import org.elasticsearch.search.internal.SearchContext;
import org.elasticsearch.search.rescore.RescoreSearchContext;
import org.elasticsearch.search.rescore.Rescorer;

import java.io.IOException;
import java.util.Map;

/**
 *
 */
public class ExplainFetchSubPhase implements FetchSubPhase {

    @Override
    public Map parseElements() {
        return ImmutableMap.of("explain", new ExplainParseElement());
    }

    @Override
    public boolean hitsExecutionNeeded(SearchContext context) {
        return false;
    }

    @Override
    public void hitsExecute(SearchContext context, InternalSearchHit[] hits) throws ElasticSearchException {
    }

    @Override
    public boolean hitExecutionNeeded(SearchContext context) {
        return context.explain();
    }

    @Override
    public void hitExecute(SearchContext context, HitContext hitContext) throws ElasticSearchException {
        try {
            final int topLevelDocId = hitContext.hit().docId();
            Explanation explanation;
            
            if (context.rescore() != null) {
                RescoreSearchContext ctx = context.rescore();
                Rescorer rescorer = ctx.rescorer();
                explanation = rescorer.explain(topLevelDocId, context, ctx);
            } else {
                explanation = context.searcher().explain(context.query(), topLevelDocId);
            }
            // we use the top level doc id, since we work with the top level searcher
            hitContext.hit().explanation(explanation);
        } catch (IOException e) {
            throw new FetchPhaseExecutionException(context, "Failed to explain doc [" + hitContext.hit().type() + "#" + hitContext.hit().id() + "]", e);
        }
    }
}