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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.ImmutableMap;
import com.google.common.collect.Lists;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.Map;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
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.simple.SimpleQueryParser;
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;
@Singleton
public class QueryDocumentationExecutor {
private static final Logger log = LoggerFactory.getLogger(QueryDocumentationExecutor.class);
private static Map<String, Float> WEIGHTS =
ImmutableMap.of(
Constants.TITLE_FIELD, 2.0f,
Constants.DOC_FIELD, 1.0f);
private IndexSearcher searcher;
private SimpleQueryParser 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 SimpleQueryParser(new StandardAnalyzer(), WEIGHTS);
} 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 (!isAvailable()) {
throw new DocQueryException("Documentation search not available");
}
Query query = parser.parse(q);
try {
// 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 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;
}
public boolean isAvailable() {
return parser != null && searcher != null;
}
public static class DocQueryException extends Exception {
private static final long serialVersionUID = 1L;
DocQueryException() {}
DocQueryException(String msg) {
super(msg);
}
DocQueryException(String msg, Throwable e) {
super(msg, e);
}
DocQueryException(Throwable e) {
super(e);
}
}
}
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