DecimalAverageAggregation.java
/*
* 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.bytecode.DynamicClassLoader;
import com.facebook.presto.common.block.Block;
import com.facebook.presto.common.block.BlockBuilder;
import com.facebook.presto.common.type.DecimalType;
import com.facebook.presto.common.type.Decimals;
import com.facebook.presto.common.type.Type;
import com.facebook.presto.common.type.UnscaledDecimal128Arithmetic;
import com.facebook.presto.metadata.BoundVariables;
import com.facebook.presto.metadata.FunctionAndTypeManager;
import com.facebook.presto.metadata.SqlAggregationFunction;
import com.facebook.presto.operator.aggregation.state.LongDecimalWithOverflowAndLongState;
import com.facebook.presto.operator.aggregation.state.LongDecimalWithOverflowAndLongStateFactory;
import com.facebook.presto.operator.aggregation.state.LongDecimalWithOverflowAndLongStateSerializer;
import com.facebook.presto.spi.function.AccumulatorState;
import com.facebook.presto.spi.function.AccumulatorStateSerializer;
import com.facebook.presto.spi.function.aggregation.Accumulator;
import com.facebook.presto.spi.function.aggregation.AggregationMetadata;
import com.facebook.presto.spi.function.aggregation.AggregationMetadata.AccumulatorStateDescriptor;
import com.facebook.presto.spi.function.aggregation.GroupedAccumulator;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import io.airlift.slice.Slice;
import java.lang.invoke.MethodHandle;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.List;
import static com.facebook.presto.common.type.Decimals.MAX_PRECISION;
import static com.facebook.presto.common.type.Decimals.MAX_SHORT_PRECISION;
import static com.facebook.presto.common.type.Decimals.writeBigDecimal;
import static com.facebook.presto.common.type.Decimals.writeShortDecimal;
import static com.facebook.presto.common.type.TypeSignature.parseTypeSignature;
import static com.facebook.presto.common.type.UnscaledDecimal128Arithmetic.UNSCALED_DECIMAL_128_SLICE_LENGTH;
import static com.facebook.presto.common.type.UnscaledDecimal128Arithmetic.unscaledDecimal;
import static com.facebook.presto.metadata.SignatureBinder.applyBoundVariables;
import static com.facebook.presto.operator.aggregation.AggregationUtils.generateAggregationName;
import static com.facebook.presto.spi.function.aggregation.AggregationMetadata.ParameterMetadata;
import static com.facebook.presto.spi.function.aggregation.AggregationMetadata.ParameterMetadata.ParameterType.BLOCK_INDEX;
import static com.facebook.presto.spi.function.aggregation.AggregationMetadata.ParameterMetadata.ParameterType.BLOCK_INPUT_CHANNEL;
import static com.facebook.presto.spi.function.aggregation.AggregationMetadata.ParameterMetadata.ParameterType.STATE;
import static com.facebook.presto.util.Reflection.methodHandle;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static com.google.common.collect.Iterables.getOnlyElement;
import static java.math.BigDecimal.ROUND_HALF_UP;
public class DecimalAverageAggregation
extends SqlAggregationFunction
{
// Constant references for short/long decimal types for use in operations that only manipulate unscaled values
private static final DecimalType LONG_DECIMAL_TYPE = DecimalType.createDecimalType(MAX_PRECISION, 0);
private static final DecimalType SHORT_DECIMAL_TYPE = DecimalType.createDecimalType(MAX_SHORT_PRECISION, 0);
public static final DecimalAverageAggregation DECIMAL_AVERAGE_AGGREGATION = new DecimalAverageAggregation();
private static final String NAME = "avg";
private static final MethodHandle SHORT_DECIMAL_INPUT_FUNCTION = methodHandle(DecimalAverageAggregation.class, "inputShortDecimal", LongDecimalWithOverflowAndLongState.class, Block.class, int.class);
private static final MethodHandle LONG_DECIMAL_INPUT_FUNCTION = methodHandle(DecimalAverageAggregation.class, "inputLongDecimal", LongDecimalWithOverflowAndLongState.class, Block.class, int.class);
private static final MethodHandle SHORT_DECIMAL_OUTPUT_FUNCTION = methodHandle(DecimalAverageAggregation.class, "outputShortDecimal", DecimalType.class, LongDecimalWithOverflowAndLongState.class, BlockBuilder.class);
private static final MethodHandle LONG_DECIMAL_OUTPUT_FUNCTION = methodHandle(DecimalAverageAggregation.class, "outputLongDecimal", DecimalType.class, LongDecimalWithOverflowAndLongState.class, BlockBuilder.class);
private static final MethodHandle COMBINE_FUNCTION = methodHandle(DecimalAverageAggregation.class, "combine", LongDecimalWithOverflowAndLongState.class, LongDecimalWithOverflowAndLongState.class);
private static final BigInteger OVERFLOW_MULTIPLIER = new BigInteger("2").shiftLeft(UNSCALED_DECIMAL_128_SLICE_LENGTH * 8 - 2);
public DecimalAverageAggregation()
{
super(NAME,
ImmutableList.of(),
ImmutableList.of(),
parseTypeSignature("decimal(p,s)", ImmutableSet.of("p", "s")),
ImmutableList.of(parseTypeSignature("decimal(p,s)", ImmutableSet.of("p", "s"))));
}
@Override
public String getDescription()
{
return "Calculates the average value";
}
@Override
public BuiltInAggregationFunctionImplementation specialize(BoundVariables boundVariables, int arity, FunctionAndTypeManager functionAndTypeManager)
{
Type type = getOnlyElement(applyBoundVariables(functionAndTypeManager, getSignature().getArgumentTypes(), boundVariables));
return generateAggregation(type);
}
private static BuiltInAggregationFunctionImplementation generateAggregation(Type type)
{
checkArgument(type instanceof DecimalType, "type must be Decimal");
DynamicClassLoader classLoader = new DynamicClassLoader(DecimalAverageAggregation.class.getClassLoader());
List<Type> inputTypes = ImmutableList.of(type);
MethodHandle inputFunction;
MethodHandle outputFunction;
Class<? extends AccumulatorState> stateInterface = LongDecimalWithOverflowAndLongState.class;
AccumulatorStateSerializer<?> stateSerializer = new LongDecimalWithOverflowAndLongStateSerializer();
if (((DecimalType) type).isShort()) {
inputFunction = SHORT_DECIMAL_INPUT_FUNCTION;
outputFunction = SHORT_DECIMAL_OUTPUT_FUNCTION;
}
else {
inputFunction = LONG_DECIMAL_INPUT_FUNCTION;
outputFunction = LONG_DECIMAL_OUTPUT_FUNCTION;
}
outputFunction = outputFunction.bindTo(type);
AggregationMetadata metadata = new AggregationMetadata(
generateAggregationName(NAME, type.getTypeSignature(), inputTypes.stream().map(Type::getTypeSignature).collect(toImmutableList())),
createInputParameterMetadata(type),
inputFunction,
COMBINE_FUNCTION,
outputFunction,
ImmutableList.of(new AccumulatorStateDescriptor(
stateInterface,
stateSerializer,
new LongDecimalWithOverflowAndLongStateFactory())),
type);
Type intermediateType = stateSerializer.getSerializedType();
Class<? extends Accumulator> accumulatorClass = AccumulatorCompiler.generateAccumulatorClass(
Accumulator.class,
metadata,
classLoader);
Class<? extends GroupedAccumulator> groupedAccumulatorClass = AccumulatorCompiler.generateAccumulatorClass(
GroupedAccumulator.class,
metadata,
classLoader);
return new BuiltInAggregationFunctionImplementation(NAME, inputTypes, ImmutableList.of(intermediateType), type,
true, false, metadata, accumulatorClass, groupedAccumulatorClass);
}
private static List<ParameterMetadata> createInputParameterMetadata(Type type)
{
return ImmutableList.of(new ParameterMetadata(STATE), new ParameterMetadata(BLOCK_INPUT_CHANNEL, type), new ParameterMetadata(BLOCK_INDEX));
}
public static void inputShortDecimal(LongDecimalWithOverflowAndLongState state, Block block, int position)
{
state.incrementLong();
Slice currentSum = state.getLongDecimal();
if (currentSum == null) {
currentSum = unscaledDecimal();
state.setLongDecimal(currentSum);
}
state.addOverflow(UnscaledDecimal128Arithmetic.addWithOverflow(currentSum, unscaledDecimal(SHORT_DECIMAL_TYPE.getLong(block, position)), currentSum));
}
public static void inputLongDecimal(LongDecimalWithOverflowAndLongState state, Block block, int position)
{
state.incrementLong();
Slice currentSum = state.getLongDecimal();
if (currentSum == null) {
currentSum = unscaledDecimal();
state.setLongDecimal(currentSum);
}
state.addOverflow(UnscaledDecimal128Arithmetic.addWithOverflow(currentSum, LONG_DECIMAL_TYPE.getSlice(block, position), currentSum));
}
public static void combine(LongDecimalWithOverflowAndLongState state, LongDecimalWithOverflowAndLongState otherState)
{
state.addLong(otherState.getLong());
long overflowToAdd = otherState.getOverflow();
Slice currentState = state.getLongDecimal();
Slice otherDecimal = otherState.getLongDecimal();
if (currentState == null) {
state.setLongDecimal(otherDecimal);
}
else {
overflowToAdd += UnscaledDecimal128Arithmetic.addWithOverflow(currentState, otherDecimal, currentState);
}
state.addOverflow(overflowToAdd);
}
public static void outputShortDecimal(DecimalType type, LongDecimalWithOverflowAndLongState state, BlockBuilder out)
{
long count = state.getLong();
if (count == 0) {
out.appendNull();
}
else {
writeShortDecimal(out, average(count, state.getOverflow(), state.getLongDecimal(), type.getScale()).unscaledValue().longValueExact());
}
}
public static void outputLongDecimal(DecimalType type, LongDecimalWithOverflowAndLongState state, BlockBuilder out)
{
long count = state.getLong();
if (count == 0) {
out.appendNull();
}
else {
writeBigDecimal(type, out, average(count, state.getOverflow(), state.getLongDecimal(), type.getScale()));
}
}
@VisibleForTesting
public static BigDecimal average(LongDecimalWithOverflowAndLongState state, DecimalType type)
{
return average(state.getLong(), state.getOverflow(), state.getLongDecimal(), type.getScale());
}
private static BigDecimal average(long count, long overflow, Slice unscaledDecimal, int scale)
{
BigDecimal sum = new BigDecimal(Decimals.decodeUnscaledValue(unscaledDecimal), scale);
if (overflow != 0) {
sum = sum.add(new BigDecimal(OVERFLOW_MULTIPLIER.multiply(BigInteger.valueOf(overflow))));
}
return sum.divide(BigDecimal.valueOf(count), scale, ROUND_HALF_UP);
}
}