[GitHub] [pinot] richardstartin commented on a diff in pull request #8384: Implement Native Text Operator

[GitBox <gi...@apache.org>]

richardstartin commented on code in PR #8384:
URL: https://github.com/apache/pinot/pull/8384#discussion_r861243152


##########
pinot-segment-local/src/main/java/org/apache/pinot/segment/local/utils/nativefst/NativeTextIndexCreator.java:
##########
@@ -0,0 +1,171 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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.apache.pinot.segment.local.utils.nativefst;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+import org.apache.commons.io.FileUtils;
+import org.apache.lucene.analysis.Analyzer;
+import org.apache.lucene.analysis.TokenStream;
+import org.apache.lucene.analysis.standard.StandardAnalyzer;
+import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
+import org.apache.pinot.segment.local.segment.creator.impl.inv.BitmapInvertedIndexWriter;
+import org.apache.pinot.segment.local.segment.creator.impl.text.LuceneTextIndexCreator;
+import org.apache.pinot.segment.local.utils.nativefst.builder.FSTBuilder;
+import org.apache.pinot.segment.spi.V1Constants;
+import org.apache.pinot.segment.spi.index.creator.TextIndexCreator;
+import org.roaringbitmap.Container;
+import org.roaringbitmap.RoaringBitmap;
+import org.roaringbitmap.RoaringBitmapWriter;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+
+public class NativeTextIndexCreator implements TextIndexCreator {
+  static final String TEMP_DIR_SUFFIX = ".nativetext.idx.tmp";
+  static final String FST_FILE_NAME = "native.fst";
+  static final String INVERTED_INDEX_FILE_NAME = "inverted.index.buf";
+  public static final int HEADER_LENGTH = 24;
+
+  private String _columnName;
+  private FSTBuilder _fstBuilder;
+  private final File _indexFile;
+  private final File _tempDir;
+  private final File _fstIndexFile;
+  private final File _invertedIndexFile;
+  final Map<String, RoaringBitmapWriter<RoaringBitmap>> _postingListMap = new TreeMap<>();
+  final RoaringBitmapWriter.Wizard<Container, RoaringBitmap> _bitmapWriterWizard = RoaringBitmapWriter.writer();
+  private int _nextDocId = 0;
+  private int _fstDataSize;
+  private int _numBitMaps;
+
+  public NativeTextIndexCreator(String column, File indexDir)
+      throws IOException {
+    _columnName = column;
+    _fstBuilder = new FSTBuilder();
+    _indexFile = new File(indexDir, column + V1Constants.Indexes.NATIVE_TEXT_INDEX_FILE_EXTENSION);
+    _tempDir = new File(indexDir, column + TEMP_DIR_SUFFIX);
+    if (_tempDir.exists()) {
+      FileUtils.cleanDirectory(_tempDir);
+    } else {
+      FileUtils.forceMkdir(_tempDir);
+    }
+    _fstIndexFile = new File(_tempDir, FST_FILE_NAME);
+    _invertedIndexFile = new File(_tempDir, INVERTED_INDEX_FILE_NAME);
+  }
+
+  @Override
+  public void add(String document) {
+    List<String> tokens;
+    try {
+      tokens = analyze(document, new StandardAnalyzer(LuceneTextIndexCreator.ENGLISH_STOP_WORDS_SET));
+    } catch (IOException e) {
+      throw new RuntimeException(e.getMessage());
+    }
+
+    for (String token : tokens) {
+      addToPostingList(token);
+    }
+
+    _nextDocId++;
+  }
+
+  @Override
+  public void add(String[] documents, int length) {
+    throw new UnsupportedOperationException("Not supported yet");
+  }
+
+  @Override
+  public void seal()
+      throws IOException {
+    int dictId = 0;
+    int numPostingLists = _postingListMap.size();
+    try (BitmapInvertedIndexWriter invertedIndexWriter = new BitmapInvertedIndexWriter(_invertedIndexFile,
+        numPostingLists)) {
+
+      for (Map.Entry<String, RoaringBitmapWriter<RoaringBitmap>> entry : _postingListMap.entrySet()) {
+        byte[] byteArray = entry.getKey().getBytes(UTF_8);
+        _fstBuilder.add(byteArray, 0, byteArray.length, dictId++);
+        invertedIndexWriter.add(entry.getValue().get());
+      }
+    }
+
+    FST fst = _fstBuilder.complete();
+    _fstDataSize = fst.save(new FileOutputStream(_fstIndexFile));
+    generateIndexFile();
+  }
+
+  @Override
+  public void close()
+      throws IOException {
+    FileUtils.deleteDirectory(_tempDir);
+  }
+
+  public List<String> analyze(String text, Analyzer analyzer)
+      throws IOException {
+    List<String> result = new ArrayList<String>();
+    TokenStream tokenStream = analyzer.tokenStream(_columnName, text);
+    CharTermAttribute attr = tokenStream.addAttribute(CharTermAttribute.class);
+    tokenStream.reset();
+    while (tokenStream.incrementToken()) {
+      result.add(attr.toString());
+    }
+    return result;
+  }
+
+  /**
+   * Adds the given value to the posting list.
+   */
+  void addToPostingList(String value) {
+    RoaringBitmapWriter<RoaringBitmap> bitmapWriter = _postingListMap.get(value);
+    if (bitmapWriter == null) {
+      bitmapWriter = _bitmapWriterWizard.get();
+      _postingListMap.put(value, bitmapWriter);
+      _numBitMaps++;
+    }
+    bitmapWriter.add(_nextDocId);
+  }
+
+  private void generateIndexFile()
+      throws IOException {
+    ByteBuffer headerBuffer = ByteBuffer.allocate(HEADER_LENGTH);
+    long invertedIndexFileLength = _invertedIndexFile.length();
+    headerBuffer.putInt(FSTHeader.FST_MAGIC);
+    headerBuffer.putLong(invertedIndexFileLength);
+    headerBuffer.putLong(_fstDataSize);
+    headerBuffer.putInt(_numBitMaps);
+    headerBuffer.position(0);
+
+    try (FileChannel indexFileChannel = new RandomAccessFile(_indexFile, "rw").getChannel();
+        FileChannel invertedIndexFileChannel = new RandomAccessFile(_invertedIndexFile, "r").getChannel();
+        FileChannel fstFileChannel = new RandomAccessFile(_fstIndexFile, "rw").getChannel()) {
+      indexFileChannel.write(headerBuffer);
+      fstFileChannel.transferTo(0, _fstDataSize, indexFileChannel);
+      invertedIndexFileChannel.transferTo(0, invertedIndexFileLength, indexFileChannel);
+    }
+  }

Review Comment:
   You can use `MmapFileWriter` here, write the header in the lambda.



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