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
   *
   *     https://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.avro.ipc;
  
  import java.util.List;
  import java.util.ArrayList;
  import java.io.IOException;
  import java.net.SocketAddress;
  import java.nio.Buffer;
  import java.nio.ByteBuffer;
  import java.nio.channels.DatagramChannel;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * A datagram-based {@link Transceiver} implementation. This uses a simple,
   * non-standard wire protocol and is not intended for production services.
   */
  public class DatagramTransceiver extends Transceiver {
    private static final Logger LOG = LoggerFactory.getLogger(DatagramTransceiver.class);
  
    private static final int MAX_SIZE = 16 * 1024;
  
    private DatagramChannel channel;
    private SocketAddress remote;
    private ByteBuffer buffer = ByteBuffer.allocate(MAX_SIZE);
  
    @Override
    public String getRemoteName() {
      return remote.toString();
    }
  
    public DatagramTransceiver(SocketAddress remote) throws IOException {
      this(DatagramChannel.open());
      this.remote = remote;
    }
  
    public DatagramTransceiver(DatagramChannel channel) {
      this.channel = channel;
    }
  
    @Override
    public synchronized List<ByteBuffer> readBuffers() throws IOException {
      ((Buffer) buffer).clear();
      remote = channel.receive(buffer);
      LOG.info("received from " + remote);
      ((Buffer) buffer).flip();
      List<ByteBuffer> buffers = new ArrayList<>();
      while (true) {
        int length = buffer.getInt();
        if (length == 0) { // end of buffers
          return buffers;
        }
        ByteBuffer chunk = buffer.slice(); // use data without copying
        ((Buffer) chunk).limit(length);
        ((Buffer) buffer).position(buffer.position() + length);
        buffers.add(chunk);
      }
    }
  
    @Override
    public synchronized void writeBuffers(List<ByteBuffer> buffers) throws IOException {
      ((Buffer) buffer).clear();
      for (ByteBuffer b : buffers) {
        buffer.putInt(b.remaining());
        buffer.put(b); // copy data. sigh.
      }
      buffer.putInt(0);
      ((Buffer) buffer).flip();
      channel.send(buffer, remote);
      LOG.info("sent to " + remote);
    }
  
  }
  