Java 类org.apache.lucene.index.FilterLeafReader 实例源码

/**
 * Tries to extract a segment reader from the given index reader.
 * If no SegmentReader can be extracted an {@link IllegalStateException} is thrown.
 */
protected static SegmentReader segmentReader(LeafReader reader) {
    if (reader instanceof SegmentReader) {
        return (SegmentReader) reader;
    } else if (reader instanceof FilterLeafReader) {
        final FilterLeafReader fReader = (FilterLeafReader) reader;
        return segmentReader(FilterLeafReader.unwrap(fReader));
    }
    // hard fail - we can't get a SegmentReader
    throw new IllegalStateException("Can not extract segment reader from given index reader [" + reader + "]");
}

public static ElasticsearchLeafReader getElasticsearchLeafReader(LeafReader reader) {
    if (reader instanceof FilterLeafReader) {
        if (reader instanceof ElasticsearchLeafReader) {
            return (ElasticsearchLeafReader) reader;
        } else {
            // We need to use FilterLeafReader#getDelegate and not FilterLeafReader#unwrap, because
            // If there are multiple levels of filtered leaf readers then with the unwrap() method it immediately
            // returns the most inner leaf reader and thus skipping of over any other filtered leaf reader that
            // may be instance of ElasticsearchLeafReader. This can cause us to miss the shardId.
            return getElasticsearchLeafReader(((FilterLeafReader) reader).getDelegate());
        }
    }
    return null;
}

/**
 * Tries to extract a segment reader from the given index reader.
 * If no SegmentReader can be extracted an {@link IllegalStateException} is thrown.
 */
protected static SegmentReader segmentReader(LeafReader reader) {
    if (reader instanceof SegmentReader) {
        return (SegmentReader) reader;
    } else if (reader instanceof FilterLeafReader) {
        final FilterLeafReader fReader = (FilterLeafReader) reader;
        return segmentReader(FilterLeafReader.unwrap(fReader));
    }
    // hard fail - we can't get a SegmentReader
    throw new IllegalStateException("Can not extract segment reader from given index reader [" + reader + "]");
}

/**
 * Expert: creates a searcher from the provided {@link IndexReader} using the provided {@link
 * SearcherFactory}. NOTE: this decRefs incoming reader on throwing an exception.
 */
@SuppressWarnings("resource")
public static IndexSearcher getSearcher(SearcherFactory searcherFactory, IndexReader reader)
    throws IOException {
  boolean success = false;
  final IndexSearcher searcher;
  try {
    searcher = searcherFactory.newSearcher(reader, null);
    // Modification for Gerrit: Allow searcherFactory to transitively wrap the
    // provided reader.
    IndexReader unwrapped = searcher.getIndexReader();
    while (true) {
      if (unwrapped == reader) {
        break;
      } else if (unwrapped instanceof FilterDirectoryReader) {
        unwrapped = ((FilterDirectoryReader) unwrapped).getDelegate();
      } else if (unwrapped instanceof FilterLeafReader) {
        unwrapped = ((FilterLeafReader) unwrapped).getDelegate();
      } else {
        break;
      }
    }

    if (unwrapped != reader) {
      throw new IllegalStateException(
          "SearcherFactory must wrap the provided reader (got "
              + searcher.getIndexReader()
              + " but expected "
              + reader
              + ")");
    }
    success = true;
  } finally {
    if (!success) {
      reader.decRef();
    }
  }
  return searcher;
}