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.kafka.common.compress;
  
  import org.apache.kafka.common.KafkaException;
  import org.apache.kafka.common.record.CompressionType;
  import org.apache.kafka.common.utils.BufferSupplier;
  import org.apache.kafka.common.utils.ByteBufferInputStream;
  import org.apache.kafka.common.utils.ByteBufferOutputStream;
  import org.apache.kafka.common.utils.ChunkedBytesStream;
  
  import java.io.BufferedOutputStream;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.util.Objects;
  import java.util.zip.GZIPInputStream;
  
  import static org.apache.kafka.common.record.CompressionType.GZIP;
  
  public class GzipCompression implements Compression {
  
      private final int level;
  
      private GzipCompression(int level) {
          this.level = level;
      }
  
      @Override
      public CompressionType type() {
          return GZIP;
      }
  
      @Override
      public OutputStream wrapForOutput(ByteBufferOutputStream buffer, byte messageVersion) {
          try {
              // Set input buffer (uncompressed) to 16 KB (none by default) and output buffer (compressed) to
              // 8 KB (0.5 KB by default) to ensure reasonable performance in cases where the caller passes a small
              // number of bytes to write (potentially a single byte)
              return new BufferedOutputStream(new GzipOutputStream(buffer, 8 * 1024, level), 16 * 1024);
          } catch (Exception e) {
              throw new KafkaException(e);
          }
      }
  
      @Override
      public InputStream wrapForInput(ByteBuffer buffer, byte messageVersion, BufferSupplier decompressionBufferSupplier) {
          try {
              // Set input buffer (compressed) to 8 KB (GZIPInputStream uses 0.5 KB by default) to ensure reasonable
              // performance in cases where the caller reads a small number of bytes (potentially a single byte).
              //
              // Size of output buffer (uncompressed) is provided by decompressionOutputSize.
              //
              // ChunkedBytesStream is used to wrap the GZIPInputStream because the default implementation of
              // GZIPInputStream does not use an intermediate buffer for decompression in chunks.
              return new ChunkedBytesStream(new GZIPInputStream(new ByteBufferInputStream(buffer), 8 * 1024),
                                            decompressionBufferSupplier,
                                            decompressionOutputSize(),
                                            false);
          } catch (Exception e) {
              throw new KafkaException(e);
          }
      }
  
      @Override
      public int decompressionOutputSize() {
          // 16KB has been chosen based on legacy implementation introduced in https://github.com/apache/kafka/pull/6785
          return 16 * 1024;
      }
  
      @Override
      public boolean equals(Object o) {
          if (this == o) return true;
          if (o == null || getClass() != o.getClass()) return false;
          GzipCompression that = (GzipCompression) o;
          return level == that.level;
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(level);
      }
  
      public static class Builder implements Compression.Builder<GzipCompression> {
          private int level = GZIP.defaultLevel();
  
          public Builder level(int level) {
              if ((level < GZIP.minLevel() || GZIP.maxLevel() < level) && level != GZIP.defaultLevel()) {
                  throw new IllegalArgumentException("gzip doesn't support given compression level: " + level);
              }
  
              this.level = level;
              return this;
          }
  
          @Override
          public GzipCompression build() {
              return new GzipCompression(level);
          }
      }
  }
  