org.neo4j.kernel.api.impl.schema.sampler.NonUniqueLuceneIndexSampler.java Source code

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Here is the source code for org.neo4j.kernel.api.impl.schema.sampler.NonUniqueLuceneIndexSampler.java

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/*
 * Copyright (c) 2002-2016 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.kernel.api.impl.schema.sampler;

import org.apache.lucene.index.Fields;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.index.Terms;
import org.apache.lucene.index.TermsEnum;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.util.BytesRef;

import java.io.IOException;
import java.util.HashSet;
import java.util.Set;

import org.neo4j.helpers.TaskControl;
import org.neo4j.kernel.api.exceptions.index.IndexNotFoundKernelException;
import org.neo4j.kernel.api.impl.schema.LuceneDocumentStructure;
import org.neo4j.kernel.impl.api.index.sampling.IndexSamplingConfig;
import org.neo4j.kernel.impl.api.index.sampling.NonUniqueIndexSampler;
import org.neo4j.storageengine.api.schema.IndexSample;

/**
 * Sampler for non-unique Lucene schema index.
 * Internally uses terms and their document frequencies for sampling.
 */
public class NonUniqueLuceneIndexSampler extends LuceneIndexSampler {
    private final IndexSearcher indexSearcher;
    private final IndexSamplingConfig indexSamplingConfig;

    public NonUniqueLuceneIndexSampler(IndexSearcher indexSearcher, TaskControl taskControl,
            IndexSamplingConfig indexSamplingConfig) {
        super(taskControl);
        this.indexSearcher = indexSearcher;
        this.indexSamplingConfig = indexSamplingConfig;
    }

    @Override
    protected IndexSample performSampling() throws IndexNotFoundKernelException {
        NonUniqueIndexSampler sampler = new NonUniqueIndexSampler(indexSamplingConfig.sampleSizeLimit());
        IndexReader indexReader = indexSearcher.getIndexReader();
        for (LeafReaderContext readerContext : indexReader.leaves()) {
            try {
                Set<String> fieldNames = getFieldNamesToSample(readerContext);
                for (String fieldName : fieldNames) {
                    Terms terms = readerContext.reader().terms(fieldName);
                    if (terms != null) {
                        TermsEnum termsEnum = LuceneDocumentStructure.originalTerms(terms, fieldName);
                        BytesRef termsRef;
                        while ((termsRef = termsEnum.next()) != null) {
                            sampler.include(termsRef.utf8ToString(), termsEnum.docFreq());
                            checkCancellation();
                        }
                    }
                }
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }

        return sampler.result(indexReader.numDocs());
    }

    private static Set<String> getFieldNamesToSample(LeafReaderContext readerContext) throws IOException {
        Fields fields = readerContext.reader().fields();
        Set<String> fieldNames = new HashSet<>();
        for (String field : fields) {
            if (!LuceneDocumentStructure.NODE_ID_KEY.equals(field)) {
                fieldNames.add(field);
            }
        }
        return fieldNames;
    }
}