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// Copyright 2020 Oath Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package ai.vespa.hosted.cd.metric;
import java.util.HashMap;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.StringJoiner;
import static java.util.Map.copyOf;
import static java.util.stream.Collectors.reducing;
import static java.util.stream.Collectors.toUnmodifiableMap;
/**
* A set of statistics for a metric, for points over a space with named dimensions of arbitrary type.
*
* @author jonmv
*/
public class Metric {
private final Map<Map<String, ?>, Statistic> statistics;
private Metric(Map<Map<String, ?>, Statistic> statistics) {
this.statistics = statistics;
}
/** Creates a new Metric with a copy of the given data. */
public static Metric of(Map<Map<String, ?>, Statistic> data) {
if (data.isEmpty())
throw new IllegalArgumentException("No data given.");
Map<Map<String, ?>, Statistic> copies = new HashMap<>();
Set<String> dimensions = data.keySet().iterator().next().keySet();
data.forEach((point, statistic) -> {
if ( ! point.keySet().equals(dimensions))
throw new IllegalArgumentException("Given data has inconsistent dimensions: '" + dimensions + "' vs '" + point.keySet() + "'.");
copies.put(copyOf(point), statistic);
});
return new Metric(copyOf(copies));
}
/** Returns a Metric view of the subset of points in the given hyperplane; its dimensions must be a subset of those of this Metric. */
public Metric at(Map<String, ?> hyperplane) {
return new Metric(statistics.keySet().stream()
.filter(point -> point.entrySet().containsAll(hyperplane.entrySet()))
.collect(toUnmodifiableMap(point -> point, statistics::get)));
}
/** Returns a version of this where statistics along the given hyperspace are aggregated. This does not preserve last, 95 and 99 percentile values. */
public Metric collapse(Set<String> hyperspace) {
return new Metric(statistics.keySet().stream()
.collect(toUnmodifiableMap(point -> point.keySet().stream()
.filter(dimension -> ! hyperspace.contains(dimension))
.collect(toUnmodifiableMap(dimension -> dimension, point::get)),
statistics::get,
Statistic::mergedWith)));
}
/** Returns a collapsed version of this, with all statistics aggregated. This does not preserve last, 95 and 99 percentile values. */
public Metric collapse() {
Map<String, ?> firstStatistic = statistics.keySet().iterator().next();
return firstStatistic == null ? this : collapse(firstStatistic.keySet());
}
/** If this Metric contains a single point, returns the Statistic of that point; otherwise, throws an exception. */
public Statistic statistic() {
if (statistics.size() == 1)
return statistics.values().iterator().next();
if (statistics.isEmpty())
throw new NoSuchElementException("This Metric has no data.");
throw new IllegalStateException("This Metric has more than one point of data.");
}
/** Returns the underlying, unmodifiable Map. */
public Map<Map<String, ?>, Statistic> asMap() {
return statistics;
}
@Override
public String toString() {
return new StringJoiner(", ", Metric.class.getSimpleName() + "[", "]")
.add("statistics=" + statistics)
.toString();
}
}
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