/*
* 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.operator.aggregation.state.HyperLogLogState;
import com.facebook.presto.operator.aggregation.state.StateCompiler;
import com.facebook.presto.spi.block.BlockBuilder;
import com.facebook.presto.spi.function.AccumulatorStateSerializer;
import com.facebook.presto.spi.function.AggregationFunction;
import com.facebook.presto.spi.function.AggregationState;
import com.facebook.presto.spi.function.CombineFunction;
import com.facebook.presto.spi.function.InputFunction;
import com.facebook.presto.spi.function.LiteralParameters;
import com.facebook.presto.spi.function.OutputFunction;
import com.facebook.presto.spi.function.SqlType;
import com.facebook.presto.spi.type.StandardTypes;
import io.airlift.slice.Slice;
import io.airlift.stats.cardinality.HyperLogLog;
@AggregationFunction("approx_set")
public final class ApproximateSetAggregation
{
private static final int NUMBER_OF_BUCKETS = 4096;
private static final AccumulatorStateSerializer<HyperLogLogState> SERIALIZER = StateCompiler.generateStateSerializer(HyperLogLogState.class);
private ApproximateSetAggregation() {}
public static HyperLogLog newHyperLogLog()
{
return HyperLogLog.newInstance(NUMBER_OF_BUCKETS);
}
@InputFunction
public static void input(@AggregationState HyperLogLogState state, @SqlType(StandardTypes.DOUBLE) double value)
{
HyperLogLog hll = getOrCreateHyperLogLog(state);
state.addMemoryUsage(-hll.estimatedInMemorySize());
hll.add(Double.doubleToLongBits(value));
state.addMemoryUsage(hll.estimatedInMemorySize());
}
@InputFunction
@LiteralParameters("x")
public static void input(@AggregationState HyperLogLogState state, @SqlType("varchar(x)") Slice value)
{
HyperLogLog hll = getOrCreateHyperLogLog(state);
state.addMemoryUsage(-hll.estimatedInMemorySize());
hll.add(value);
state.addMemoryUsage(hll.estimatedInMemorySize());
}
@InputFunction
public static void input(@AggregationState HyperLogLogState state, @SqlType(StandardTypes.BIGINT) long value)
{
HyperLogLog hll = getOrCreateHyperLogLog(state);
state.addMemoryUsage(-hll.estimatedInMemorySize());
hll.add(value);
state.addMemoryUsage(hll.estimatedInMemorySize());
}
private static HyperLogLog getOrCreateHyperLogLog(@AggregationState HyperLogLogState state)
{
HyperLogLog hll = state.getHyperLogLog();
if (hll == null) {
hll = newHyperLogLog();
state.setHyperLogLog(hll);
state.addMemoryUsage(hll.estimatedInMemorySize());
}
return hll;
}
@CombineFunction
public static void combineState(@AggregationState HyperLogLogState state, @AggregationState HyperLogLogState otherState)
{
HyperLogLog input = otherState.getHyperLogLog();
HyperLogLog previous = state.getHyperLogLog();
if (previous == null) {
state.setHyperLogLog(input);
state.addMemoryUsage(input.estimatedInMemorySize());
}
else {
state.addMemoryUsage(-previous.estimatedInMemorySize());
previous.mergeWith(input);
state.addMemoryUsage(previous.estimatedInMemorySize());
}
}
@OutputFunction(StandardTypes.HYPER_LOG_LOG)
public static void evaluateFinal(@AggregationState HyperLogLogState state, BlockBuilder out)
{
SERIALIZER.serialize(state, out);
}
}