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.index.internal.composites;
  
  import java.nio.ByteBuffer;
  
  import org.apache.cassandra.db.*;
  import org.apache.cassandra.db.rows.CellPath;
  import org.apache.cassandra.db.rows.Row;
  import org.apache.cassandra.index.internal.CassandraIndex;
  import org.apache.cassandra.index.internal.IndexEntry;
  import org.apache.cassandra.schema.IndexMetadata;
  
  /**
   * Common superclass for indexes that capture collection keys, including
   * indexes on such keys themselves.
   *
   * A cell indexed by this index will have the general form:
   *   ck_0 ... ck_n c_name [col_elt] : v
   * where ck_i are the cluster keys, c_name the CQL3 column name, col_elt the
   * collection element that we want to index (which may or may not be there depending
   * on whether c_name is the collection we're indexing), and v the cell value.
   *
   * Such a cell is indexed if c_name is the indexed collection (in which case we are guaranteed to have
   * col_elt). The index entry can be viewed in the following way:
   *   - the row key is determined by subclasses of this type.
   *   - the cell name will be 'rk ck_0 ... ck_n' where rk is the row key of the initial cell.
   */
  public abstract class CollectionKeyIndexBase extends CassandraIndex
  {
      public CollectionKeyIndexBase(ColumnFamilyStore baseCfs, IndexMetadata indexDef)
      {
          super(baseCfs, indexDef);
      }
  
      public <T> CBuilder buildIndexClusteringPrefix(ByteBuffer partitionKey,
                                                     ClusteringPrefix<T> prefix,
                                                     CellPath path)
      {
          CBuilder builder = CBuilder.create(getIndexComparator());
          builder.add(partitionKey);
  
          // When indexing a static column, prefix will be empty but only the
          // partition key is needed at query time.
          for (int i = 0; i < prefix.size(); i++)
              builder.add(prefix.get(i), prefix.accessor());
  
          return builder;
      }
  
      public IndexEntry decodeEntry(DecoratedKey indexedValue,
                                    Row indexEntry)
      {
          Clustering<?> clustering = indexEntry.clustering();
  
          Clustering<?> indexedEntryClustering = null;
          if (getIndexedColumn().isStatic())
              indexedEntryClustering = Clustering.STATIC_CLUSTERING;
          else
          {
              int count = 1 + baseCfs.metadata().clusteringColumns().size();
              CBuilder builder = CBuilder.create(baseCfs.getComparator());
              for (int i = 0; i < count - 1; i++)
                  builder.add(clustering, i + 1);
              indexedEntryClustering = builder.build();
          }
  
          return new IndexEntry(indexedValue,
                                clustering,
                                indexEntry.primaryKeyLivenessInfo().timestamp(),
                                clustering.bufferAt(0),
                                indexedEntryClustering);
      }
  }
  