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.streaming.async;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.channels.ReadableByteChannel;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufAllocator;
  import net.jpountz.lz4.LZ4Compressor;
  import net.jpountz.lz4.LZ4SafeDecompressor;
  import org.apache.cassandra.io.util.DataInputPlus;
  import org.apache.cassandra.streaming.StreamingDataOutputPlus;
  
  import static org.apache.cassandra.net.MessagingService.current_version;
  
  /**
   * A serialiazer for stream compressed files (see package-level documentation). Much like a typical compressed
   * output stream, this class operates on buffers or chunks of the data at a a time. The format for each compressed
   * chunk is as follows:
   *
   * - int - compressed payload length
   * - int - uncompressed payload length
   * - bytes - compressed payload
   */
  public class StreamCompressionSerializer
  {
      private final ByteBufAllocator allocator;
  
      public StreamCompressionSerializer(ByteBufAllocator allocator)
      {
          this.allocator = allocator;
      }
  
      /**
       * Length of heaer data, which includes compressed length, uncompressed length.
       */
      private static final int HEADER_LENGTH = 8;
  
      public static StreamingDataOutputPlus.Write serialize(LZ4Compressor compressor, ByteBuffer in, int version)
      {
          assert version == current_version;
          return bufferSupplier -> {
              int uncompressedLength = in.remaining();
              int maxLength = compressor.maxCompressedLength(uncompressedLength);
              ByteBuffer out = bufferSupplier.get(maxLength);
              out.position(HEADER_LENGTH);
              compressor.compress(in, out);
              int compressedLength = out.position() - HEADER_LENGTH;
              out.putInt(0, compressedLength);
              out.putInt(4, uncompressedLength);
              out.flip();
          };
      }
  
      /**
       * @return A buffer with decompressed data.
       */
      public ByteBuf deserialize(LZ4SafeDecompressor decompressor, DataInputPlus in, int version) throws IOException
      {
          final int compressedLength = in.readInt();
          final int uncompressedLength = in.readInt();
  
          // there's no guarantee the next compressed block is contained within one buffer in the input,
          // so hence we need a 'staging' buffer to get all the bytes into one contiguous buffer for the decompressor
          ByteBuf compressed = null;
          ByteBuf uncompressed = null;
          try
          {
              final ByteBuffer compressedNioBuffer;
  
              // ReadableByteChannel allows us to keep the bytes off-heap because we pass a ByteBuffer to RBC.read(BB),
              // DataInputPlus.read() takes a byte array (thus, an on-heap array).
              if (in instanceof ReadableByteChannel)
              {
                  compressed = allocator.directBuffer(compressedLength);
                  compressedNioBuffer = compressed.nioBuffer(0, compressedLength);
                  int readLength = ((ReadableByteChannel) in).read(compressedNioBuffer);
                  assert readLength == compressedNioBuffer.position();
                  compressedNioBuffer.flip();
              }
              else
              {
                  byte[] compressedBytes = new byte[compressedLength];
                  in.readFully(compressedBytes);
                  compressedNioBuffer = ByteBuffer.wrap(compressedBytes);
              }
  
              uncompressed = allocator.directBuffer(uncompressedLength);
              ByteBuffer uncompressedNioBuffer = uncompressed.nioBuffer(0, uncompressedLength);
              decompressor.decompress(compressedNioBuffer, uncompressedNioBuffer);
              uncompressed.writerIndex(uncompressedLength);
              return uncompressed;
          }
          catch (Exception e)
          {
              if (uncompressed != null)
                  uncompressed.release();
  
              if (e instanceof IOException)
                  throw e;
              throw new IOException(e);
          }
          finally
          {
              if (compressed != null)
                  compressed.release();
          }
      }
  }
  