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.util.Collection;
  
  import net.nicoulaj.compilecommand.annotations.Inline;
  
  /**
   * An abstract frame decoder for frames utilising a fixed length header of 8 bytes or smaller.
   * Implements a generic frame decode method, that is backed by the four abstract methods
   * (three of which simply decode and verify the header as a long).
   *
   * Implementors are expected to declare their implementation methods final, and an outer decode
   * method implemented to invoke this class' {@link #decode}, so that it may be inlined with the
   * abstract method implementations then inlined into it.
   */
  abstract class FrameDecoderWith8bHeader extends FrameDecoder
  {
      FrameDecoderWith8bHeader(BufferPoolAllocator allocator)
      {
          super(allocator);
      }
  
      /**
       * Read a header that is 8 bytes or shorter, without modifying the buffer position.
       * If your header is longer than this, you will need to implement your own {@link #decode}
       */
      abstract long readHeader(ByteBuffer in, int begin);
      /**
       * Verify the header, and return an unrecoverable CorruptFrame if it is corrupted
       * @return null or CorruptFrame.unrecoverable
       */
      abstract CorruptFrame verifyHeader(long header);
  
      /**
       * Calculate the full frame length from info provided by the header, including the length of the header and any triler
       */
      abstract int frameLength(long header);
  
      /**
       * Extract a frame known to cover the given range.
       * If {@code transferOwnership}, the method is responsible for ensuring bytes.release() is invoked at some future point.
       */
      abstract Frame unpackFrame(ShareableBytes bytes, int begin, int end, long header);
  
      /**
       * Decode a number of frames using the above abstract method implementations.
       * It is expected for this method to be invoked by the implementing class' {@link #decode(Collection, ShareableBytes)}
       * so that this implementation will be inlined, and all of the abstract method implementations will also be inlined.
       */
      @Inline
      protected void decode(Collection<Frame> into, ShareableBytes newBytes, int headerLength)
      {
          ByteBuffer in = newBytes.get();
  
          try
          {
              if (stash != null)
              {
                  if (!copyToSize(in, stash, headerLength))
                      return;
  
                  long header = readHeader(stash, 0);
                  CorruptFrame c = verifyHeader(header);
                  if (c != null)
                  {
                      discard();
                      into.add(c);
                      return;
                  }
  
                  int frameLength = frameLength(header);
                  stash = ensureCapacity(stash, frameLength);
  
                  if (!copyToSize(in, stash, frameLength))
                      return;
  
                  stash.flip();
                  ShareableBytes stashed = ShareableBytes.wrap(stash);
                  stash = null;
  
                  try
                  {
                      into.add(unpackFrame(stashed, 0, frameLength, header));
                  }
                  finally
                  {
                      stashed.release();
                  }
              }
  
              int begin = in.position();
              int limit = in.limit();
              while (begin < limit)
              {
                  int remaining = limit - begin;
                  if (remaining < headerLength)
                  {
                      stash(newBytes, headerLength, begin, remaining);
                      return;
                  }
  
                  long header = readHeader(in, begin);
                  CorruptFrame c = verifyHeader(header);
                  if (c != null)
                  {
                      into.add(c);
                      return;
                  }
  
                  int frameLength = frameLength(header);
                  if (remaining < frameLength)
                  {
                      stash(newBytes, frameLength, begin, remaining);
                      return;
                  }
  
                  into.add(unpackFrame(newBytes, begin, begin + frameLength, header));
                  begin += frameLength;
              }
          }
          finally
          {
              newBytes.release();
          }
      }
  }
  