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.distributedlog.io;
  
  import static com.google.common.base.Preconditions.checkArgument;
  import static com.google.common.base.Preconditions.checkNotNull;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.CompositeByteBuf;
  import io.netty.buffer.PooledByteBufAllocator;
  
  /**
   * An identity compression codec implementation for {@link CompressionCodec}.
   */
  public class IdentityCompressionCodec implements CompressionCodec {
  
      public static IdentityCompressionCodec of() {
          return INSTANCE;
      }
  
      private static final IdentityCompressionCodec INSTANCE = new IdentityCompressionCodec();
  
      @Override
      public ByteBuf compress(ByteBuf uncompressed, int headerLen) {
          checkNotNull(uncompressed);
          checkArgument(uncompressed.readableBytes() >= 0);
          if (headerLen == 0) {
              return uncompressed.retain();
          } else {
              CompositeByteBuf composited = PooledByteBufAllocator.DEFAULT.compositeBuffer(2);
              composited.addComponent(PooledByteBufAllocator.DEFAULT.buffer(headerLen, headerLen));
              composited.addComponent(uncompressed.retain());
              return composited;
          }
      }
  
      @Override
      public ByteBuf decompress(ByteBuf compressed, int decompressedSize) {
          checkNotNull(compressed);
          checkArgument(compressed.readableBytes() >= 0);
          checkArgument(decompressedSize >= 0);
          return compressed.retain();
      }
  }
  