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.db.aggregation;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  
  import org.apache.cassandra.db.Clustering;
  import org.apache.cassandra.db.ClusteringComparator;
  import org.apache.cassandra.db.TypeSizes;
  import org.apache.cassandra.io.util.DataInputPlus;
  import org.apache.cassandra.io.util.DataOutputPlus;
  import org.apache.cassandra.utils.ByteBufferUtil;
  
  /**
   * {@code GroupMaker} state.
   *
   * <p>The state contains the primary key of the last row that has been processed by the previous
   * {@code GroupMaker} used. It can be passed to a {@code GroupMaker} to allow to resuming the grouping.
   * </p>
   * <p>
   * {@code GroupingState} is only used for internal paging. When a new page is requested by a client the initial state
   * will always be empty.</p>
   * <p>
   * If the state has a partition key but no clustering, it means that the previous group ended at the end of the
   * previous partition. If the clustering is not null it means that we are in the middle of a group.
   * </p>
   */
  public final class GroupingState
  {
      public static final GroupingState.Serializer serializer = new Serializer();
  
      public static final GroupingState EMPTY_STATE = new GroupingState(null, null);
  
      /**
       * The last row partition key.
       */
      private final ByteBuffer partitionKey;
  
      /**
       * The last row clustering
       */
      final Clustering<?> clustering;
  
      public GroupingState(ByteBuffer partitionKey, Clustering<?> clustering)
      {
          this.partitionKey = partitionKey;
          this.clustering = clustering;
      }
  
      /**
       * Returns the last row partition key or <code>null</code> if no rows has been processed yet.
       * @return the last row partition key or <code>null</code> if no rows has been processed yet
       */
      public ByteBuffer partitionKey()
      {
          return partitionKey;
      }
  
      /**
       * Returns the last row clustering or <code>null</code> if either no rows has been processed yet or the last
       * row was a static row.
       * @return he last row clustering or <code>null</code> if either no rows has been processed yet or the last
       * row was a static row
       */
      public Clustering<?> clustering()
      {
          return clustering;
      }
  
      /**
       * Checks if the state contains a Clustering for the last row that has been processed.
       * @return <code>true</code> if the state contains a Clustering for the last row that has been processed,
       * <code>false</code> otherwise.
       */
      public boolean hasClustering()
      {
          return clustering != null;
      }
  
      public static class Serializer
      {
          public void serialize(GroupingState state, DataOutputPlus out, int version, ClusteringComparator comparator) throws IOException
          {
              boolean hasPartitionKey = state.partitionKey != null;
              out.writeBoolean(hasPartitionKey);
              if (hasPartitionKey)
              {
                  ByteBufferUtil.writeWithVIntLength(state.partitionKey, out);
                  boolean hasClustering = state.hasClustering();
                  out.writeBoolean(hasClustering);
                  if (hasClustering)
                      Clustering.serializer.serialize(state.clustering, out, version, comparator.subtypes());
              }
          }
  
          public GroupingState deserialize(DataInputPlus in, int version, ClusteringComparator comparator) throws IOException
          {
              if (!in.readBoolean())
                  return GroupingState.EMPTY_STATE;
  
              ByteBuffer partitionKey = ByteBufferUtil.readWithVIntLength(in);
              Clustering<byte[]> clustering = null;
              if (in.readBoolean())
                  clustering = Clustering.serializer.deserialize(in, version, comparator.subtypes());
  
              return new GroupingState(partitionKey, clustering);
          }
  
          public long serializedSize(GroupingState state, int version, ClusteringComparator comparator)
          {
              boolean hasPartitionKey = state.partitionKey != null;
              long size = TypeSizes.sizeof(hasPartitionKey);
              if (hasPartitionKey)
              {
                  size += ByteBufferUtil.serializedSizeWithVIntLength(state.partitionKey);
                  boolean hasClustering = state.hasClustering();
                  size += TypeSizes.sizeof(hasClustering);
                  if (hasClustering)
                  {
                      size += Clustering.serializer.serializedSize(state.clustering, version, comparator.subtypes());
                  }
              }
              return size;
          }
      }
  }
  