/*
* 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.metadata.BoundVariables;
import com.facebook.presto.metadata.FunctionRegistry;
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.block.Block;
import com.facebook.presto.spi.block.BlockBuilder;
import com.facebook.presto.spi.function.AccumulatorState;
import com.facebook.presto.spi.function.AccumulatorStateSerializer;
import com.facebook.presto.spi.type.DecimalType;
import com.facebook.presto.spi.type.Decimals;
import com.facebook.presto.spi.type.Type;
import com.facebook.presto.spi.type.TypeManager;
import com.facebook.presto.spi.type.UnscaledDecimal128Arithmetic;
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.metadata.SignatureBinder.applyBoundVariables;
import static com.facebook.presto.operator.aggregation.AggregationMetadata.ParameterMetadata;
import static com.facebook.presto.operator.aggregation.AggregationMetadata.ParameterMetadata.ParameterType.BLOCK_INDEX;
import static com.facebook.presto.operator.aggregation.AggregationMetadata.ParameterMetadata.ParameterType.BLOCK_INPUT_CHANNEL;
import static com.facebook.presto.operator.aggregation.AggregationMetadata.ParameterMetadata.ParameterType.STATE;
import static com.facebook.presto.operator.aggregation.AggregationUtils.generateAggregationName;
import static com.facebook.presto.spi.type.Decimals.writeBigDecimal;
import static com.facebook.presto.spi.type.Decimals.writeShortDecimal;
import static com.facebook.presto.spi.type.TypeSignature.parseTypeSignature;
import static com.facebook.presto.spi.type.UnscaledDecimal128Arithmetic.UNSCALED_DECIMAL_128_SLICE_LENGTH;
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
{
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", Type.class, LongDecimalWithOverflowAndLongState.class, Block.class, int.class);
private static final MethodHandle LONG_DECIMAL_INPUT_FUNCTION = methodHandle(DecimalAverageAggregation.class, "inputLongDecimal", Type.class, 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 TWO = new BigInteger("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 InternalAggregationFunction specialize(BoundVariables boundVariables, int arity, TypeManager typeManager, FunctionRegistry functionRegistry)
{
Type type = typeManager.getType(getOnlyElement(applyBoundVariables(getSignature().getArgumentTypes(), boundVariables)));
return generateAggregation(type);
}
private static InternalAggregationFunction 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;
}
inputFunction = inputFunction.bindTo(type);
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,
stateInterface,
stateSerializer,
new LongDecimalWithOverflowAndLongStateFactory(),
type);
Type intermediateType = stateSerializer.getSerializedType();
GenericAccumulatorFactoryBinder factory = AccumulatorCompiler.generateAccumulatorFactoryBinder(metadata, classLoader);
return new InternalAggregationFunction(NAME, inputTypes, intermediateType, type, true, factory);
}
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(Type type, LongDecimalWithOverflowAndLongState state, Block block, int position)
{
accumulateValueInState(UnscaledDecimal128Arithmetic.unscaledDecimal(type.getLong(block, position)), state);
}
public static void inputLongDecimal(Type type, LongDecimalWithOverflowAndLongState state, Block block, int position)
{
accumulateValueInState(type.getSlice(block, position), state);
}
private static void accumulateValueInState(Slice unscaledValue, LongDecimalWithOverflowAndLongState state)
{
accumulateAndUpdateOverflow(unscaledValue, state);
state.setLong(state.getLong() + 1);
}
private static void initializeIfNeeded(LongDecimalWithOverflowAndLongState state)
{
if (state.getLongDecimal() == null) {
state.setLongDecimal(UnscaledDecimal128Arithmetic.unscaledDecimal());
}
}
public static void combine(LongDecimalWithOverflowAndLongState state, LongDecimalWithOverflowAndLongState otherState)
{
state.setLong(state.getLong() + otherState.getLong());
state.setOverflow(state.getOverflow() + otherState.getOverflow());
if (state.getLongDecimal() == null) {
state.setLongDecimal(otherState.getLongDecimal());
}
else {
accumulateAndUpdateOverflow(otherState.getLongDecimal(), state);
}
}
public static void outputShortDecimal(DecimalType type, LongDecimalWithOverflowAndLongState state, BlockBuilder out)
{
if (state.getLong() == 0) {
out.appendNull();
}
else {
writeShortDecimal(out, average(state, type).unscaledValue().longValueExact());
}
}
public static void outputLongDecimal(DecimalType type, LongDecimalWithOverflowAndLongState state, BlockBuilder out)
{
if (state.getLong() == 0) {
out.appendNull();
}
else {
writeBigDecimal(type, out, average(state, type));
}
}
@VisibleForTesting
public static BigDecimal average(LongDecimalWithOverflowAndLongState state, DecimalType type)
{
BigDecimal sum = new BigDecimal(Decimals.decodeUnscaledValue(state.getLongDecimal()), type.getScale());
BigDecimal count = BigDecimal.valueOf(state.getLong());
if (state.getOverflow() != 0) {
BigInteger overflowMultiplier = TWO.shiftLeft(UNSCALED_DECIMAL_128_SLICE_LENGTH * 8 - 2);
BigInteger overflow = overflowMultiplier.multiply(BigInteger.valueOf(state.getOverflow()));
sum = sum.add(new BigDecimal(overflow));
}
return sum.divide(count, type.getScale(), ROUND_HALF_UP);
}
private static void accumulateAndUpdateOverflow(Slice unscaledValue, LongDecimalWithOverflowAndLongState state)
{
initializeIfNeeded(state);
Slice sum = state.getLongDecimal();
long overflow = UnscaledDecimal128Arithmetic.addWithOverflow(sum, unscaledValue, sum);
state.setOverflow(state.getOverflow() + overflow);
}
}