/*
* 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 com.facebook.presto.operator.aggregation;
import com.facebook.presto.block.Block;
import com.facebook.presto.block.BlockBuilder;
import com.facebook.presto.block.BlockCursor;
import com.facebook.presto.operator.GroupByIdBlock;
import com.facebook.presto.util.array.ObjectBigArray;
import com.google.common.base.Optional;
import io.airlift.slice.Slice;
import static com.facebook.presto.tuple.TupleInfo.SINGLE_VARBINARY;
import static com.facebook.presto.tuple.TupleInfo.Type.VARIABLE_BINARY;
import static com.google.common.base.Preconditions.checkState;
public class VarBinaryMaxAggregation
extends SimpleAggregationFunction
{
public static final VarBinaryMaxAggregation VAR_BINARY_MAX = new VarBinaryMaxAggregation();
public VarBinaryMaxAggregation()
{
super(SINGLE_VARBINARY, SINGLE_VARBINARY, VARIABLE_BINARY);
}
@Override
protected GroupedAccumulator createGroupedAccumulator(Optional<Integer> maskChannel, int valueChannel)
{
// Min/max are not effected by distinct, so ignore it.
return new VarBinaryMaxGroupedAccumulator(valueChannel);
}
public static class VarBinaryMaxGroupedAccumulator
extends SimpleGroupedAccumulator
{
private final ObjectBigArray<Slice> maxValues;
private long sizeOfValues;
public VarBinaryMaxGroupedAccumulator(int valueChannel)
{
super(valueChannel, SINGLE_VARBINARY, SINGLE_VARBINARY, Optional.<Integer>absent());
this.maxValues = new ObjectBigArray<>();
}
@Override
public long getEstimatedSize()
{
return maxValues.sizeOf() + sizeOfValues;
}
@Override
protected void processInput(GroupByIdBlock groupIdsBlock, Block valuesBlock, Optional<Block> maskBlock)
{
maxValues.ensureCapacity(groupIdsBlock.getGroupCount());
BlockCursor values = valuesBlock.cursor();
for (int position = 0; position < groupIdsBlock.getPositionCount(); position++) {
checkState(values.advanceNextPosition());
// skip null values
if (!values.isNull()) {
long groupId = groupIdsBlock.getGroupId(position);
Slice value = values.getSlice();
Slice currentValue = maxValues.get(groupId);
if (currentValue == null || value.compareTo(currentValue) > 0) {
maxValues.set(groupId, value);
// update size
if (currentValue != null) {
sizeOfValues -= currentValue.length();
}
sizeOfValues += value.length();
}
}
}
checkState(!values.advanceNextPosition());
}
@Override
public void evaluateFinal(int groupId, BlockBuilder output)
{
Slice value = maxValues.get((long) groupId);
if (value == null) {
output.appendNull();
}
else {
output.append(value);
}
}
}
@Override
protected Accumulator createAccumulator(Optional<Integer> maskChannel, int valueChannel)
{
// Min/max are not effected by distinct, so ignore it.
return new VarBinaryMaxAccumulator(valueChannel);
}
public static class VarBinaryMaxAccumulator
extends SimpleAccumulator
{
private Slice max;
public VarBinaryMaxAccumulator(int valueChannel)
{
super(valueChannel, SINGLE_VARBINARY, SINGLE_VARBINARY, Optional.<Integer>absent());
}
@Override
protected void processInput(Block block, Optional<Block> maskBlock)
{
BlockCursor values = block.cursor();
for (int position = 0; position < block.getPositionCount(); position++) {
checkState(values.advanceNextPosition());
if (!values.isNull()) {
max = max(max, values.getSlice());
}
}
}
@Override
public void evaluateFinal(BlockBuilder out)
{
if (max != null) {
out.append(max);
}
else {
out.appendNull();
}
}
}
private static Slice max(Slice a, Slice b)
{
if (a == null) {
return b;
}
if (b == null) {
return a;
}
return a.compareTo(b) > 0 ? a : b;
}
}