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.sstable.metadata;
  
  import java.io.IOException;
  
  import com.clearspring.analytics.stream.cardinality.HyperLogLogPlus;
  import com.clearspring.analytics.stream.cardinality.ICardinality;
  
  import org.apache.cassandra.db.TypeSizes;
  import org.apache.cassandra.io.sstable.format.Version;
  import org.apache.cassandra.io.util.DataInputPlus;
  import org.apache.cassandra.io.util.DataOutputPlus;
  import org.apache.cassandra.utils.ByteArrayUtil;
  import org.apache.cassandra.utils.ByteBufferUtil;
  
  /**
   * Compaction related SSTable metadata.
   *
   * Only loaded for <b>compacting</b> SSTables at the time of compaction.
   */
  public class CompactionMetadata extends MetadataComponent
  {
      public static final IMetadataComponentSerializer serializer = new CompactionMetadataSerializer();
  
      public final ICardinality cardinalityEstimator;
  
      public CompactionMetadata(ICardinality cardinalityEstimator)
      {
          this.cardinalityEstimator = cardinalityEstimator;
      }
  
      public MetadataType getType()
      {
          return MetadataType.COMPACTION;
      }
  
      @Override
      public boolean equals(Object o)
      {
          if (this == o)
              return true;
  
          if (o == null || getClass() != o.getClass())
              return false;
  
          // keeping equals and hashCode as all classes inheriting from MetadataComponent
          // implement them but we have really nothing to compare
          return true;
      }
  
      @Override
      public int hashCode()
      {
          // see comment in equals
          return 31;
      }
  
      public static class CompactionMetadataSerializer implements IMetadataComponentSerializer<CompactionMetadata>
      {
          public int serializedSize(Version version, CompactionMetadata component) throws IOException
          {
              int sz = 0;
              byte[] serializedCardinality = component.cardinalityEstimator.getBytes();
              return TypeSizes.sizeof(serializedCardinality.length) + serializedCardinality.length + sz;
          }
  
          public void serialize(Version version, CompactionMetadata component, DataOutputPlus out) throws IOException
          {
              ByteArrayUtil.writeWithLength(component.cardinalityEstimator.getBytes(), out);
          }
  
          public CompactionMetadata deserialize(Version version, DataInputPlus in) throws IOException
          {
              ICardinality cardinality = HyperLogLogPlus.Builder.build(ByteBufferUtil.readBytes(in, in.readInt()));
              return new CompactionMetadata(cardinality);
          }
      }
  }
  