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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.

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/*
 * 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.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.
 */
public class PartitionKeyIndex extends CassandraIndex
{
    private final boolean enforceStrictLiveness;
    public PartitionKeyIndex(ColumnFamilyStore baseCfs, IndexMetadata indexDef)
    {
        super(baseCfs, indexDef);
        this.enforceStrictLiveness = baseCfs.metadata.get().enforceStrictLiveness();
    }

    public ByteBuffer getIndexedValue(ByteBuffer partitionKey,
                                      Clustering clustering,
                                      CellPath path,
                                      ByteBuffer cellValue)
    {
        CompositeType keyComparator = (CompositeType)baseCfs.metadata().partitionKeyType;
        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), prefix.accessor());
        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, i + 1);

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

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