/*
* Druid - a distributed column store.
* Copyright (C) 2012, 2013, 2014 Metamarkets Group Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package io.druid.query.aggregation.cardinality;
import io.druid.query.aggregation.BufferAggregator;
import io.druid.query.aggregation.hyperloglog.HyperLogLogCollector;
import io.druid.segment.DimensionSelector;
import java.nio.ByteBuffer;
import java.util.List;
public class CardinalityBufferAggregator implements BufferAggregator
{
private final List<DimensionSelector> selectorList;
private final boolean byRow;
private static final byte[] EMPTY_BYTES = HyperLogLogCollector.makeEmptyVersionedByteArray();
public CardinalityBufferAggregator(
List<DimensionSelector> selectorList,
boolean byRow
)
{
this.selectorList = selectorList;
this.byRow = byRow;
}
@Override
public void init(ByteBuffer buf, int position)
{
final ByteBuffer mutationBuffer = buf.duplicate();
mutationBuffer.position(position);
mutationBuffer.put(EMPTY_BYTES);
}
@Override
public void aggregate(ByteBuffer buf, int position)
{
final HyperLogLogCollector collector = HyperLogLogCollector.makeCollector(
(ByteBuffer) buf.duplicate().position(position).limit(
position
+ HyperLogLogCollector.getLatestNumBytesForDenseStorage()
)
);
if (byRow) {
CardinalityAggregator.hashRow(selectorList, collector);
} else {
CardinalityAggregator.hashValues(selectorList, collector);
}
}
@Override
public Object get(ByteBuffer buf, int position)
{
ByteBuffer dataCopyBuffer = ByteBuffer.allocate(HyperLogLogCollector.getLatestNumBytesForDenseStorage());
ByteBuffer mutationBuffer = buf.duplicate();
mutationBuffer.position(position);
mutationBuffer.get(dataCopyBuffer.array());
return HyperLogLogCollector.makeCollector(dataCopyBuffer);
}
@Override
public float getFloat(ByteBuffer buf, int position)
{
throw new UnsupportedOperationException("CardinalityBufferAggregator does not support getFloat()");
}
@Override
public long getLong(ByteBuffer buf, int position)
{
throw new UnsupportedOperationException("CardinalityBufferAggregator does not support getLong()");
}
@Override
public void close()
{
// no resources to cleanup
}
}