com.google.gerrit.server.documentation.QueryDocumentationExecutor.java Source code

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Here is the source code for com.google.gerrit.server.documentation.QueryDocumentationExecutor.java

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// Copyright (C) 2013 The Android Open Source Project
//
// Licensed 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 com.google.gerrit.server.documentation;

import com.google.common.collect.Lists;
import com.google.inject.Inject;
import com.google.inject.Singleton;

import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.queryparser.classic.ParseException;
import org.apache.lucene.queryparser.classic.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.IndexOutput;
import org.apache.lucene.store.RAMDirectory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

@Singleton
public class QueryDocumentationExecutor {
    private static final Logger log = LoggerFactory.getLogger(QueryDocumentationExecutor.class);

    private IndexSearcher searcher;
    private QueryParser parser;

    public static class DocResult {
        public String title;
        public String url;
        public String content;
    }

    @Inject
    public QueryDocumentationExecutor() {
        try {
            Directory dir = readIndexDirectory();
            if (dir == null) {
                searcher = null;
                parser = null;
                return;
            }
            IndexReader reader = DirectoryReader.open(dir);
            searcher = new IndexSearcher(reader);
            parser = new QueryParser(Constants.DOC_FIELD, new StandardAnalyzer());
        } catch (IOException e) {
            log.error("Cannot initialize documentation full text index", e);
            searcher = null;
            parser = null;
        }
    }

    public List<DocResult> doQuery(String q) throws DocQueryException {
        if (parser == null || searcher == null) {
            throw new DocQueryException("Documentation search not available");
        }
        try {
            Query query = parser.parse(q);
            // TODO(fishywang): Currently as we don't have much documentation, we just use MAX_VALUE here
            // and skipped paging. Maybe add paging later.
            TopDocs results = searcher.search(query, Integer.MAX_VALUE);
            ScoreDoc[] hits = results.scoreDocs;
            int totalHits = results.totalHits;

            List<DocResult> out = Lists.newArrayListWithCapacity(totalHits);
            for (int i = 0; i < totalHits; i++) {
                DocResult result = new DocResult();
                Document doc = searcher.doc(hits[i].doc);
                result.url = doc.get(Constants.URL_FIELD);
                result.title = doc.get(Constants.TITLE_FIELD);
                out.add(result);
            }
            return out;
        } catch (IOException | ParseException e) {
            throw new DocQueryException(e);
        }
    }

    protected Directory readIndexDirectory() throws IOException {
        Directory dir = new RAMDirectory();
        byte[] buffer = new byte[4096];
        InputStream index = getClass().getResourceAsStream(Constants.INDEX_ZIP);
        if (index == null) {
            log.warn("No index available");
            return null;
        }

        try (ZipInputStream zip = new ZipInputStream(index)) {
            ZipEntry entry;
            while ((entry = zip.getNextEntry()) != null) {
                try (IndexOutput out = dir.createOutput(entry.getName(), null)) {
                    int count;
                    while ((count = zip.read(buffer)) != -1) {
                        out.writeBytes(buffer, count);
                    }
                }
            }
        }
        // We must NOT call dir.close() here, as DirectoryReader.open() expects an opened directory.
        return dir;
    }

    @SuppressWarnings("serial")
    public static class DocQueryException extends Exception {
        DocQueryException() {
        }

        DocQueryException(String msg) {
            super(msg);
        }

        DocQueryException(String msg, Throwable e) {
            super(msg, e);
        }

        DocQueryException(Throwable e) {
            super(e);
        }
    }
}