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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.searchlib.aggregation;
import com.yahoo.searchlib.aggregation.hll.*;
import com.yahoo.searchlib.expression.IntegerResultNode;
import com.yahoo.searchlib.expression.ResultNode;
import com.yahoo.vespa.objects.Deserializer;
import com.yahoo.vespa.objects.ObjectVisitor;
import com.yahoo.vespa.objects.Serializer;
/**
* This is an aggregated result holding the number of unique documents matching a given expression.
*
* @author bjorncs
*/
public class ExpressionCountAggregationResult extends AggregationResult {
public static final int classId = registerClass(0x4000 + 88, ExpressionCountAggregationResult.class, ExpressionCountAggregationResult::new);
private static final int UNDEFINED = -1;
// The unique count estimator
private final UniqueCountEstimator<Sketch<?>> estimator;
// Sketch merger
private final SketchMerger sketchMerger = new SketchMerger();
// The sketch used as basis for the unique count calculation. The sketch is populated with data by the search nodes.
private Sketch<?> sketch;
// The estimated unique count. This value will not be serialized / deserialized.
private long estimatedUniqueCount = UNDEFINED;
/** Constructor used for deserialization. Will be instantiated with a default sketch. */
public ExpressionCountAggregationResult() {
this(new SparseSketch(), new HyperLogLogEstimator());
}
/**
* Constructs an instance with a given sketch, sketch merger and unique count estimator. For test purposes.
*
* @param initialSketch the HLL sketch
*/
public ExpressionCountAggregationResult(Sketch<?> initialSketch, UniqueCountEstimator<Sketch<?>> estimator) {
this.sketch = initialSketch;
this.estimator = estimator;
}
/**
* @return The unique count estimated by the HyperLogLog algorithm.
*/
public long getEstimatedUniqueCount() {
if (estimatedUniqueCount == UNDEFINED) {
updateEstimate();
}
return estimatedUniqueCount;
}
@Override
public ResultNode getRank() {
return new IntegerResultNode(getEstimatedUniqueCount());
}
@Override
protected void onMerge(AggregationResult result) {
ExpressionCountAggregationResult other = (ExpressionCountAggregationResult) result;
sketch = sketchMerger.merge(sketch, other.sketch);
// Any cached result should be invalidated.
estimatedUniqueCount = UNDEFINED;
}
public Sketch<?> getSketch() {
return sketch;
}
@Override
protected int onGetClassId() {
return classId;
}
@Override
protected void onSerialize(Serializer buf) {
super.onSerialize(buf);
sketch.serializeWithId(buf);
}
@Override
protected void onDeserialize(Deserializer buf) {
super.onDeserialize(buf);
sketch = (Sketch<?>) create(buf);
}
@Override
protected boolean equalsAggregation(AggregationResult obj) {
// obj is assumed to always be of correct type.
ExpressionCountAggregationResult other = (ExpressionCountAggregationResult) obj;
return sketch.equals(other.sketch);
}
private void updateEstimate() {
estimatedUniqueCount = estimator.estimateCount(sketch);
}
@Override
public void visitMembers(ObjectVisitor visitor) {
super.visitMembers(visitor);
visitor.visit("sketch", sketch);
}
@Override
public int hashCode() {
int result = super.hashCode();
result = 31 * result + sketch.hashCode();
return result;
}
}
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