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.io.compress;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.util.Map;
  import java.util.Set;
  
  import com.google.common.collect.ImmutableMap;
  import com.google.common.collect.ImmutableSet;
  
  import org.apache.cassandra.utils.ByteBufferUtil;
  
  /**
   * Mock compressor used to test the effect of different output sizes in compression.
   * Writes only the size of the given buffer, and on decompression expands to sequence of that many 0s.
   */
  public class MockCompressor implements ICompressor
  {
      final int extra;
      final double ratio;
  
      public static Map<String, String> paramsFor(double ratio, int extra)
      {
          return ImmutableMap.of("extra", "" + extra, "ratio", "" + ratio);
      }
  
      public static MockCompressor create(Map<String, String> opts)
      {
          return new MockCompressor(Integer.parseInt(opts.get("extra")),
                                    Double.parseDouble(opts.get("ratio")));
      }
  
      private MockCompressor(int extra, double ratio)
      {
          this.extra = extra;
          this.ratio = ratio;
      }
  
      public int initialCompressedBufferLength(int chunkLength)
      {
          return (int) Math.ceil(chunkLength / ratio + extra);
      }
  
      public int uncompress(byte[] input, int inputOffset, int inputLength, byte[] output, int outputOffset)
      throws IOException
      {
          final ByteBuffer outputBuffer = ByteBuffer.wrap(output, outputOffset, output.length - outputOffset);
          uncompress(ByteBuffer.wrap(input, inputOffset, inputLength),
                     outputBuffer);
          return outputBuffer.position();
      }
  
      public void compress(ByteBuffer input, ByteBuffer output) throws IOException
      {
          int inputLength = input.remaining();
          int outputLength = initialCompressedBufferLength(inputLength);
          // assume the input is all zeros, write its length and pad until the required size
          output.putInt(inputLength);
          for (int i = 4; i < outputLength; ++i)
              output.put((byte) i);
          input.position(input.limit());
      }
  
      public void uncompress(ByteBuffer input, ByteBuffer output) throws IOException
      {
          int outputLength = input.getInt();
          ByteBufferUtil.writeZeroes(output, outputLength);
      }
  
      public BufferType preferredBufferType()
      {
          return BufferType.OFF_HEAP;
      }
  
      public boolean supports(BufferType bufferType)
      {
          return true;
      }
  
      public Set<String> supportedOptions()
      {
          return ImmutableSet.of("extra", "ratio");
      }
  
  }
  