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.cassandra.net;
  
  import java.nio.ByteBuffer;
  import java.nio.ByteOrder;
  import java.util.zip.CRC32;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.channel.ChannelHandler;
  
  import static org.apache.cassandra.utils.Crc.*;
  
  /**
   * Please see {@link FrameDecoderCrc} for description of the framing produced by this encoder.
   */
  @ChannelHandler.Sharable
  public class FrameEncoderCrc extends FrameEncoder
  {
      static final int HEADER_LENGTH = 6;
      private static final int TRAILER_LENGTH = 4;
      public static final int HEADER_AND_TRAILER_LENGTH = 10;
  
      public static final FrameEncoderCrc instance = new FrameEncoderCrc();
      static final PayloadAllocator allocator = (isSelfContained, capacity) ->
          new Payload(isSelfContained, capacity, HEADER_LENGTH, TRAILER_LENGTH);
  
      public PayloadAllocator allocator()
      {
          return allocator;
      }
  
      static void writeHeader(ByteBuffer frame, boolean isSelfContained, int dataLength)
      {
          int header3b = dataLength;
          if (isSelfContained)
              header3b |= 1 << 17;
          int crc = crc24(header3b, 3);
          put3b(frame, 0, header3b);
          put3b(frame, 3, crc);
      }
  
      private static void put3b(ByteBuffer frame, int index, int put3b)
      {
          frame.put(index    , (byte) put3b        );
          frame.put(index + 1, (byte)(put3b >>> 8) );
          frame.put(index + 2, (byte)(put3b >>> 16));
      }
  
      ByteBuf encode(boolean isSelfContained, ByteBuffer frame)
      {
          try
          {
              int frameLength = frame.remaining();
              int dataLength = frameLength - HEADER_AND_TRAILER_LENGTH;
              if (dataLength >= 1 << 17)
                  throw new IllegalArgumentException("Maximum payload size is 128KiB");
  
              writeHeader(frame, isSelfContained, dataLength);
  
              CRC32 crc = crc32();
              frame.position(HEADER_LENGTH);
              frame.limit(dataLength + HEADER_LENGTH);
              crc.update(frame);
  
              int frameCrc = (int) crc.getValue();
              if (frame.order() == ByteOrder.BIG_ENDIAN)
                  frameCrc = Integer.reverseBytes(frameCrc);
  
              frame.limit(frameLength);
              frame.putInt(frameLength - TRAILER_LENGTH, frameCrc);
              frame.position(0);
  
              return GlobalBufferPoolAllocator.wrap(frame);
          }
          catch (Throwable t)
          {
              bufferPool.put(frame);
              throw t;
          }
      }
  }
  