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.flight.integration.tests;
  
  import java.util.Arrays;
  import org.apache.arrow.flight.CallStatus;
  import org.apache.arrow.flight.FlightDescriptor;
  import org.apache.arrow.flight.FlightStream;
  import org.apache.arrow.flight.NoOpFlightProducer;
  import org.apache.arrow.memory.BufferAllocator;
  import org.apache.arrow.vector.VectorLoader;
  import org.apache.arrow.vector.VectorSchemaRoot;
  import org.apache.arrow.vector.VectorUnloader;
  import org.apache.arrow.vector.ipc.message.ArrowRecordBatch;
  
  /** The server used for testing the Flight do_exchange method. */
  final class DoExchangeProducer extends NoOpFlightProducer {
    private final BufferAllocator allocator;
  
    DoExchangeProducer(BufferAllocator allocator) {
      this.allocator = allocator;
    }
  
    @Override
    public void doExchange(CallContext context, FlightStream reader, ServerStreamListener writer) {
      FlightDescriptor descriptor = reader.getDescriptor();
      if (descriptor.isCommand()) {
        if (Arrays.equals(DoExchangeEchoScenario.COMMAND, descriptor.getCommand())) {
          doEcho(reader, writer);
        }
      }
      throw CallStatus.UNIMPLEMENTED
          .withDescription("Unsupported descriptor: " + descriptor.toString())
          .toRuntimeException();
    }
  
    private void doEcho(FlightStream reader, ServerStreamListener writer) {
      VectorSchemaRoot root = null;
      VectorLoader loader = null;
      while (reader.next()) {
        if (reader.hasRoot()) {
          if (root == null) {
            root = VectorSchemaRoot.create(reader.getSchema(), allocator);
            loader = new VectorLoader(root);
            writer.start(root);
          }
          VectorUnloader unloader = new VectorUnloader(reader.getRoot());
          try (final ArrowRecordBatch arb = unloader.getRecordBatch()) {
            loader.load(arb);
          }
          if (reader.getLatestMetadata() != null) {
            reader.getLatestMetadata().getReferenceManager().retain();
            writer.putNext(reader.getLatestMetadata());
          } else {
            writer.putNext();
          }
        } else {
          // Pure metadata
          reader.getLatestMetadata().getReferenceManager().retain();
          writer.putMetadata(reader.getLatestMetadata());
        }
      }
      if (root != null) {
        root.close();
      }
      writer.completed();
    }
  }
  