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
   *
   *     https://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.avro.file;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.util.zip.Deflater;
  import java.util.zip.DeflaterOutputStream;
  import java.util.zip.Inflater;
  import java.util.zip.InflaterOutputStream;
  
  import org.apache.avro.util.NonCopyingByteArrayOutputStream;
  
  /**
   * Implements DEFLATE (RFC1951) compression and decompression.
   *
   * Note that there is a distinction between RFC1951 (deflate) and RFC1950
   * (zlib). zlib adds an extra 2-byte header at the front, and a 4-byte checksum
   * at the end. The code here, by passing "true" as the "nowrap" option to
   * {@link Inflater} and {@link Deflater}, is using RFC1951.
   */
  public class DeflateCodec extends Codec {
  
    private static final int DEFAULT_BUFFER_SIZE = 8192;
  
    static class Option extends CodecFactory {
      private final int compressionLevel;
  
      Option(int compressionLevel) {
        this.compressionLevel = compressionLevel;
      }
  
      @Override
      protected Codec createInstance() {
        return new DeflateCodec(compressionLevel);
      }
    }
  
    private Deflater deflater;
    private Inflater inflater;
    // currently only do 'nowrap' -- RFC 1951, not zlib
    private final boolean nowrap = true;
    private final int compressionLevel;
  
    public DeflateCodec(int compressionLevel) {
      this.compressionLevel = compressionLevel;
    }
  
    @Override
    public String getName() {
      return DataFileConstants.DEFLATE_CODEC;
    }
  
    @Override
    public ByteBuffer compress(ByteBuffer data) throws IOException {
      NonCopyingByteArrayOutputStream baos = new NonCopyingByteArrayOutputStream(DEFAULT_BUFFER_SIZE);
      try (OutputStream outputStream = new DeflaterOutputStream(baos, getDeflater())) {
        outputStream.write(data.array(), computeOffset(data), data.remaining());
      }
      return baos.asByteBuffer();
    }
  
    @Override
    public ByteBuffer decompress(ByteBuffer data) throws IOException {
      NonCopyingByteArrayOutputStream baos = new NonCopyingByteArrayOutputStream(DEFAULT_BUFFER_SIZE);
      try (OutputStream outputStream = new InflaterOutputStream(baos, getInflater())) {
        outputStream.write(data.array(), computeOffset(data), data.remaining());
      }
      return baos.asByteBuffer();
    }
  
    // get and initialize the inflater for use.
    private Inflater getInflater() {
      if (null == inflater) {
        inflater = new Inflater(nowrap);
      } else {
        inflater.reset();
      }
      return inflater;
    }
  
    // get and initialize the deflater for use.
    private Deflater getDeflater() {
      if (null == deflater) {
        deflater = new Deflater(compressionLevel, nowrap);
      } else {
        deflater.reset();
      }
      return deflater;
    }
  
    @Override
    public int hashCode() {
      return nowrap ? 0 : 1;
    }
  
    @Override
    public boolean equals(Object obj) {
      if (this == obj)
        return true;
      if (obj == null || obj.getClass() != getClass())
        return false;
      DeflateCodec other = (DeflateCodec) obj;
      return (this.nowrap == other.nowrap);
    }
  
    @Override
    public String toString() {
      return getName() + "-" + compressionLevel;
    }
  }
  