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A fork of the Apache Cassandra Project ready to embed Elasticsearch.
/*
* 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.service.pager;
import java.nio.ByteBuffer;
import org.apache.cassandra.db.*;
import org.apache.cassandra.db.rows.*;
import org.apache.cassandra.db.filter.*;
import org.apache.cassandra.transport.ProtocolVersion;
/**
* Common interface to single partition queries (by slice and by name).
*
* For use by MultiPartitionPager.
*/
public class SinglePartitionPager extends AbstractQueryPager
{
private final SinglePartitionReadCommand command;
private volatile PagingState.RowMark lastReturned;
public SinglePartitionPager(SinglePartitionReadCommand command, PagingState state, ProtocolVersion protocolVersion)
{
super(command, protocolVersion);
this.command = command;
if (state != null)
{
lastReturned = state.rowMark;
restoreState(command.partitionKey(), state.remaining, state.remainingInPartition);
}
}
private SinglePartitionPager(SinglePartitionReadCommand command,
ProtocolVersion protocolVersion,
PagingState.RowMark rowMark,
int remaining,
int remainingInPartition)
{
super(command, protocolVersion);
this.command = command;
this.lastReturned = rowMark;
restoreState(command.partitionKey(), remaining, remainingInPartition);
}
@Override
public SinglePartitionPager withUpdatedLimit(DataLimits newLimits)
{
return new SinglePartitionPager(command.withUpdatedLimit(newLimits),
protocolVersion,
lastReturned,
maxRemaining(),
remainingInPartition());
}
public ByteBuffer key()
{
return command.partitionKey().getKey();
}
public DataLimits limits()
{
return command.limits();
}
public PagingState state()
{
return lastReturned == null
? null
: new PagingState(null, lastReturned, maxRemaining(), remainingInPartition());
}
protected ReadCommand nextPageReadCommand(int pageSize)
{
Clustering clustering = lastReturned == null ? null : lastReturned.clustering(command.metadata());
DataLimits limits = (lastReturned == null || command.isForThrift()) ? limits().forPaging(pageSize)
: limits().forPaging(pageSize, key(), remainingInPartition());
return command.forPaging(clustering, limits);
}
protected void recordLast(DecoratedKey key, Row last)
{
if (last != null && last.clustering() != Clustering.STATIC_CLUSTERING)
lastReturned = PagingState.RowMark.create(command.metadata(), last, protocolVersion);
}
protected boolean isPreviouslyReturnedPartition(DecoratedKey key)
{
return lastReturned != null;
}
}
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