/*
* Druid - a distributed column store.
* Copyright (C) 2012, 2013 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;
import com.google.common.primitives.Floats;
import com.google.common.primitives.Longs;
import io.druid.segment.FloatColumnSelector;
import java.nio.ByteBuffer;
import java.util.Arrays;
public class HistogramBufferAggregator implements BufferAggregator
{
private final FloatColumnSelector selector;
private final float[] breaks;
private final int minOffset;
private final int maxOffset;
public HistogramBufferAggregator(FloatColumnSelector selector, float[] breaks)
{
this.selector = selector;
this.breaks = breaks;
this.minOffset = Longs.BYTES * (breaks.length + 1);
this.maxOffset = this.minOffset + Floats.BYTES;
}
@Override
public void init(ByteBuffer buf, int position)
{
ByteBuffer mutationBuffer = buf.duplicate();
mutationBuffer.position(position);
final long[] bins = new long[breaks.length + 1];
mutationBuffer.asLongBuffer().put(bins);
mutationBuffer.putFloat(position + minOffset, Float.MAX_VALUE);
mutationBuffer.putFloat(position + maxOffset, Float.MIN_VALUE);
}
@Override
public void aggregate(ByteBuffer buf, int position)
{
final float value = selector.get();
final int minPos = position + minOffset;
final int maxPos = position + maxOffset;
if(value < buf.getFloat(minPos)) buf.putFloat(minPos, value);
if(value > buf.getFloat(maxPos)) buf.putFloat(maxPos, value);
int index = Arrays.binarySearch(breaks, value);
index = (index >= 0) ? index : -(index + 1);
final int offset = position + (index * Longs.BYTES);
final long count = buf.getLong(offset);
buf.putLong(offset, count + 1);
}
@Override
public Object get(ByteBuffer buf, int position)
{
long[] bins = new long[breaks.length + 1];
ByteBuffer mutationBuffer = buf.duplicate();
mutationBuffer.position(position);
mutationBuffer.asLongBuffer().get(bins);
float min = mutationBuffer.getFloat(position + minOffset);
float max = mutationBuffer.getFloat(position + maxOffset);
return new Histogram(breaks, bins, min, max);
}
@Override
public float getFloat(ByteBuffer buf, int position)
{
throw new UnsupportedOperationException("HistogramBufferAggregator does not support getFloat()");
}
@Override
public long getLong(ByteBuffer buf, int position)
{
throw new UnsupportedOperationException("HistogramBufferAggregator does not support getLong()");
}
@Override
public void close()
{
// no resources to cleanup
}
}