io.druid.query.aggregation.HistogramBufferAggregator.java Source code

Introduction

Here is the source code for io.druid.query.aggregation.HistogramBufferAggregator.java

Source

/*
 * Druid - a distributed column store.
 * Copyright 2012 - 2015 Metamarkets Group Inc.
 *
 * Licensed 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 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
    }
}