1 files changed, 149 insertions, 0 deletions
diff --git a/java/com/google/gerrit/server/documentation/QueryDocumentationExecutor.java b/java/com/google/gerrit/server/documentation/QueryDocumentationExecutor.java
new file mode 100644
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+++ b/java/com/google/gerrit/server/documentation/QueryDocumentationExecutor.java
@@ -0,0 +1,149 @@
+// 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.flogger.FluentLogger;
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+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;
+
+@Singleton
+public class QueryDocumentationExecutor {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
+  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) {
+      logger.atSevere().withCause(e).log("Cannot initialize documentation full text index");
+      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;
+      long totalHits = results.totalHits;
+
+      List<DocResult> out = new ArrayList<>();
+      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) {
+      logger.atWarning().log("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);
+    }
+  }
+}