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 * Licensed to the Apache Software Foundation (ASF) under one
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 * 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.marshal.CompositeType;
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;

Index on a PARTITION_KEY column definition.
This suppose a composite row key:
  rk = rk_0 ... rk_n
The corresponding index entry will be:
  - index row key will be rk_i (where i == columnDef.componentIndex)
  - cell name will be: rk ck
    where rk is the fully partition key and ck the clustering keys of the
    original cell names (thus excluding the last column name as we want to refer to
    the whole CQL3 row, not just the cell itself)
Note that contrarily to other type of index, we repeat the indexed value in
the index cell name (we use the whole partition key). The reason is that we
want to order the index cell name by partitioner first, and skipping a part
of the row key would change the order.
/**
 * Index on a PARTITION_KEY column definition.
 *
 * This suppose a composite row key:
 *   rk = rk_0 ... rk_n
 *
 * The corresponding index entry will be:
 *   - index row key will be rk_i (where i == columnDef.componentIndex)
 *   - cell name will be: rk ck
 *     where rk is the fully partition key and ck the clustering keys of the
 *     original cell names (thus excluding the last column name as we want to refer to
 *     the whole CQL3 row, not just the cell itself)
 *
 * Note that contrarily to other type of index, we repeat the indexed value in
 * the index cell name (we use the whole partition key). The reason is that we
 * want to order the index cell name by partitioner first, and skipping a part
 * of the row key would change the order.
 */
public class PartitionKeyIndex extends CassandraIndex
{
    private final boolean enforceStrictLiveness;
    public PartitionKeyIndex(ColumnFamilyStore baseCfs, IndexMetadata indexDef)
    {
        super(baseCfs, indexDef);
        this.enforceStrictLiveness = baseCfs.metadata.enforceStrictLiveness();
    }

    public ByteBuffer getIndexedValue(ByteBuffer partitionKey,
                                      Clustering clustering,
                                      CellPath path,
                                      ByteBuffer cellValue)
    {
        CompositeType keyComparator = (CompositeType)baseCfs.metadata.getKeyValidator();
        ByteBuffer[] components = keyComparator.split(partitionKey);
        return components[indexedColumn.position()];
    }

    public CBuilder buildIndexClusteringPrefix(ByteBuffer partitionKey,
                                               ClusteringPrefix prefix,
                                               CellPath path)
    {
        CBuilder builder = CBuilder.create(getIndexComparator());
        builder.add(partitionKey);
        for (int i = 0; i < prefix.size(); i++)
            builder.add(prefix.get(i));
        return builder;
    }

    public IndexEntry decodeEntry(DecoratedKey indexedValue, Row indexEntry)
    {
        int ckCount = baseCfs.metadata.clusteringColumns().size();
        Clustering clustering = indexEntry.clustering();
        CBuilder builder = CBuilder.create(baseCfs.getComparator());
        for (int i = 0; i < ckCount; i++)
            builder.add(clustering.get(i + 1));

        return new IndexEntry(indexedValue,
                              clustering,
                              indexEntry.primaryKeyLivenessInfo().timestamp(),
                              clustering.get(0),
                              builder.build());
    }

    public boolean isStale(Row data, ByteBuffer indexValue, int nowInSec)
    {
        return !data.hasLiveData(nowInSec, enforceStrictLiveness);
    }
}