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.transform;
  
  import org.apache.cassandra.db.Clustering;
  import org.apache.cassandra.db.DeletionTime;
  import org.apache.cassandra.db.ReadExecutionController;
  import org.apache.cassandra.db.partitions.UnfilteredPartitionIterator;
  import org.apache.cassandra.db.rows.*;
  
  /**
   * A transformation that appends an RT bound marker to row iterators in case they don't have one.
   *
   * This used to happen, for example, in {@link org.apache.cassandra.db.ReadCommand#executeLocally(ReadExecutionController)}
   * if {@link org.apache.cassandra.db.filter.DataLimits} stopped the iterator on a live row that was enclosed in an
   * older RT.
   *
   * If we don't do this, and send a response without the closing bound, we can break read/short read protection read
   * isolation, and potentially cause data loss.
   *
   * See CASSANDRA-14515 for context.
   */
  public final class RTBoundCloser extends Transformation<UnfilteredRowIterator>
  {
      private RTBoundCloser()
      {
      }
  
      public static UnfilteredPartitionIterator close(UnfilteredPartitionIterator partitions)
      {
          return Transformation.apply(partitions, new RTBoundCloser());
      }
  
      public static UnfilteredRowIterator close(UnfilteredRowIterator partition)
      {
          RowsTransformation transformation = new RowsTransformation(partition);
          return Transformation.apply(MoreRows.extend(partition, transformation, partition.columns()), transformation);
      }
  
      @Override
      public UnfilteredRowIterator applyToPartition(UnfilteredRowIterator partition)
      {
          RowsTransformation transformation = new RowsTransformation(partition);
          return Transformation.apply(MoreRows.extend(partition, transformation, partition.columns()), transformation);
      }
  
      private final static class RowsTransformation extends Transformation implements MoreRows<UnfilteredRowIterator>
      {
          private final UnfilteredRowIterator partition;
  
          private Clustering<?> lastRowClustering;
          private DeletionTime openMarkerDeletionTime;
  
          private RowsTransformation(UnfilteredRowIterator partition)
          {
              this.partition = partition;
          }
  
          @Override
          public Row applyToRow(Row row)
          {
              lastRowClustering = row.clustering();
              return row;
          }
  
          @Override
          public RangeTombstoneMarker applyToMarker(RangeTombstoneMarker marker)
          {
              openMarkerDeletionTime =
                  marker.isOpen(partition.isReverseOrder()) ? marker.openDeletionTime(partition.isReverseOrder()) : null;
              lastRowClustering = null;
              return marker;
          }
  
          @Override
          public UnfilteredRowIterator moreContents()
          {
              // there is no open RT in the stream - nothing for us to do
              if (null == openMarkerDeletionTime)
                  return null;
  
              /*
               * there *is* an open RT in the stream, but there have been no rows after the opening bound - this must
               * never happen in scenarios where RTBoundCloser is meant to be used; the last encountered clustering
               * should be either a closing bound marker - if the iterator was exhausted fully - or a live row - if
               * DataLimits stopped it short in the middle of an RT.
               */
              if (null == lastRowClustering)
              {
                  String message = String.format("UnfilteredRowIterator for %s has an open RT bound as its last item", partition.metadata());
                  throw new IllegalStateException(message);
              }
  
              // create an artificial inclusive closing RT bound with bound matching last seen row's clustering
              RangeTombstoneBoundMarker closingBound =
                  RangeTombstoneBoundMarker.inclusiveClose(partition.isReverseOrder(), lastRowClustering, openMarkerDeletionTime);
  
              return UnfilteredRowIterators.singleton(closingBound,
                                                      partition.metadata(),
                                                      partition.partitionKey(),
                                                      partition.partitionLevelDeletion(),
                                                      partition.columns(),
                                                      partition.staticRow(),
                                                      partition.isReverseOrder(),
                                                      partition.stats());
          }
      }
  }
  