Package org.apache.flink.runtime.io.network.netty

Source Code of org.apache.flink.runtime.io.network.netty.OutboundEnvelopeEncoder

/*
* 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.flink.runtime.io.network.netty;

import org.apache.flink.runtime.io.network.Buffer;
import org.apache.flink.runtime.io.network.Envelope;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelOutboundHandlerAdapter;
import io.netty.channel.ChannelPromise;

@ChannelHandler.Sharable
public class OutboundEnvelopeEncoder extends ChannelOutboundHandlerAdapter {

  public static final int HEADER_SIZE = 48;

  public static final int MAGIC_NUMBER = 0xBADC0FFE;

  @Override
  public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
    Envelope env = (Envelope) msg;

    ByteBuf buf = ctx.alloc().directBuffer();

    encode(env, buf);

    if (buf.isReadable()) {
      ctx.write(buf, promise);
    }
    else {
      buf.release();
      ctx.write(Unpooled.EMPTY_BUFFER, promise);
    }
  }

  private void encode(Envelope env, ByteBuf out) {
    // --------------------------------------------------------------------
    // (1) header (48 bytes)
    // --------------------------------------------------------------------
    out.writeInt(MAGIC_NUMBER); // 4 bytes

    if (out.getInt(out.writerIndex() - 4) != MAGIC_NUMBER) {
      throw new RuntimeException();
    }

    out.writeInt(env.getSequenceNumber()); // 4 bytes
    env.getJobID().writeTo(out); // 16 bytes
    env.getSource().writeTo(out); // 16 bytes
    out.writeInt(env.getEventsSerialized() != null ? env.getEventsSerialized().remaining() : 0); // 4 bytes
    out.writeInt(env.getBuffer() != null ? env.getBuffer().size() : 0); // 4 bytes
    // --------------------------------------------------------------------
    // (2) events (var length)
    // --------------------------------------------------------------------
    if (env.getEventsSerialized() != null) {
      out.writeBytes(env.getEventsSerialized());
    }

    // --------------------------------------------------------------------
    // (3) buffer (var length)
    // --------------------------------------------------------------------
    if (env.getBuffer() != null) {
      Buffer envBuffer = env.getBuffer();
      out.writeBytes(envBuffer.getMemorySegment().wrap(0, envBuffer.size()));

      // Recycle the buffer from OUR buffer pool after everything has been
      // copied to Nettys buffer space.
      envBuffer.recycleBuffer();
    }
  }
}
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