content: /*
   * 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.arrow.adapter.orc;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.stream.Collectors;
  import org.apache.arrow.memory.ArrowBuf;
  import org.apache.arrow.memory.BufferAllocator;
  import org.apache.arrow.vector.ipc.ArrowReader;
  import org.apache.arrow.vector.ipc.ReadChannel;
  import org.apache.arrow.vector.ipc.message.ArrowFieldNode;
  import org.apache.arrow.vector.ipc.message.ArrowRecordBatch;
  import org.apache.arrow.vector.ipc.message.MessageChannelReader;
  import org.apache.arrow.vector.ipc.message.MessageResult;
  import org.apache.arrow.vector.ipc.message.MessageSerializer;
  import org.apache.arrow.vector.types.pojo.Schema;
  import org.apache.arrow.vector.util.ByteArrayReadableSeekableByteChannel;
  
  /** Orc stripe that load data into ArrowRecordBatch. */
  public class OrcStripeReader extends ArrowReader {
    /** reference to native stripe reader instance. */
    private final long nativeInstanceId;
  
    /**
     * Construct a new instance.
     *
     * @param nativeInstanceId nativeInstanceId of the stripe reader instance, obtained by calling
     *     nextStripeReader from OrcReaderJniWrapper
     * @param allocator memory allocator for accounting.
     */
    OrcStripeReader(long nativeInstanceId, BufferAllocator allocator) {
      super(allocator);
      this.nativeInstanceId = nativeInstanceId;
    }
  
    @Override
    public boolean loadNextBatch() throws IOException {
      OrcRecordBatch recordBatch = OrcStripeReaderJniWrapper.next(nativeInstanceId);
      if (recordBatch == null) {
        return false;
      }
  
      ArrayList<ArrowBuf> buffers = new ArrayList<>();
      for (OrcMemoryJniWrapper buffer : recordBatch.buffers) {
        buffers.add(
            new ArrowBuf(
                new OrcReferenceManager(buffer),
                null,
                (int) buffer.getSize(),
                buffer.getMemoryAddress()));
      }
  
      loadRecordBatch(
          new ArrowRecordBatch(
              recordBatch.length,
              recordBatch.nodes.stream()
                  .map(buf -> new ArrowFieldNode(buf.getLength(), buf.getNullCount()))
                  .collect(Collectors.toList()),
              buffers));
      return true;
    }
  
    @Override
    public long bytesRead() {
      return 0;
    }
  
    @Override
    protected void closeReadSource() throws IOException {
      OrcStripeReaderJniWrapper.close(nativeInstanceId);
    }
  
    @Override
    protected Schema readSchema() throws IOException {
      byte[] schemaBytes = OrcStripeReaderJniWrapper.getSchema(nativeInstanceId);
  
      try (MessageChannelReader schemaReader =
          new MessageChannelReader(
              new ReadChannel(new ByteArrayReadableSeekableByteChannel(schemaBytes)), allocator)) {
  
        MessageResult result = schemaReader.readNext();
        if (result == null) {
          throw new IOException("Unexpected end of input. Missing schema.");
        }
  
        return MessageSerializer.deserializeSchema(result.getMessage());
      }
    }
  }
  