content: /*
   * Copyright (c) 2013 - 2014, Allen A. George <allen dot george at gmail dot com>
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *     * Redistributions of source code must retain the above copyright
   *       notice, this list of conditions and the following disclaimer.
   *     * Redistributions in binary form must reproduce the above copyright
   *       notice, this list of conditions and the following disclaimer in the
   *       documentation and/or other materials provided with the distribution.
   *     * Neither the name of libraft nor the
   *       names of its contributors may be used to endorse or promote products
   *       derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
   * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package io.libraft.agent.rpc;
  
  import org.jboss.netty.handler.codec.frame.LengthFieldBasedFrameDecoder;
  import org.jboss.netty.handler.codec.frame.LengthFieldPrepender;
  
  /**
   * Provides {@link org.jboss.netty.channel.ChannelHandler} implementations
   * that convert {@code RaftNetworkClient} messages to/from length-field-prepended
   * packets suitable for network transmission.
   */
  abstract class Framers {
  
      private static final int MAX_FRAME_LENGTH = 10 * 1024 * 1024; // 10 MB
      private static final int LENGTH_FIELD_OFFSET = 0;
      private static final int LENGTH_FIELD_LENGTH = 2;
      private static final int LENGTH_ADJUSTMENT = 0; // length field does not include the length of the length field itself
  
      private Framers() { } // to prevent instantiation
  
      /**
       * Stateful {@link org.jboss.netty.channel.ChannelHandler} that converts
       * an incoming stream of bytes into a series of discrete packets.
       *
       * @see LengthFieldBasedFrameDecoder
       */
      static final class FrameDecoder extends LengthFieldBasedFrameDecoder {
  
          /**
           * Constructor.
           */
          FrameDecoder() {
              super(MAX_FRAME_LENGTH, LENGTH_FIELD_OFFSET, LENGTH_FIELD_LENGTH, LENGTH_ADJUSTMENT, LENGTH_FIELD_LENGTH);
          }
      }
  
      /**
       * Stateful {@link org.jboss.netty.channel.ChannelHandler} that
       * prepends outgoing packets with a length-field header.
       *
       * @see LengthFieldPrepender
       */
      static final class FrameEncoder extends LengthFieldPrepender {
  
          /**
           * Constructor.
           */
          FrameEncoder() {
              super(LENGTH_FIELD_LENGTH);
          }
      }
  }
  