eu.xenit.alfred.telemetry.util.MeterRegistryUtil Maven / Gradle / Ivy

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package eu.xenit.alfred.telemetry.util;

import io.micrometer.core.instrument.Meter;
import io.micrometer.core.instrument.MeterRegistry;
import io.micrometer.core.instrument.Statistic;
import io.micrometer.core.instrument.Tag;
import io.micrometer.core.instrument.composite.CompositeMeterRegistry;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;
import java.util.function.BiFunction;

public class MeterRegistryUtil {

    public static Collection findFirstMatchingMeters(MeterRegistry registry, String name, Iterable tags) {
        if (registry instanceof CompositeMeterRegistry) {
            return findFirstMatchingMeters((CompositeMeterRegistry) registry, name, tags);
        }
        return registry.find(name).tags(tags).meters();
    }

    public static Map getSamples(Collection meters) {
        Map samples = new LinkedHashMap<>();
        meters.forEach((meter) -> mergeMeasurements(samples, meter));
        return samples;
    }

    public static Map> getAvailableTags(Collection meters) {
        Map> availableTags = new HashMap<>();
        meters.forEach((meter) -> mergeAvailableTags(availableTags, meter));
        return availableTags;
    }

    /* PRIVATE METHODS */

    private static Collection findFirstMatchingMeters(CompositeMeterRegistry composite, String name,
            Iterable tags) {
        return composite.getRegistries().stream().map((registry) -> findFirstMatchingMeters(registry, name, tags))
                .filter((matching) -> !matching.isEmpty()).findFirst().orElse(Collections.emptyList());
    }

    private static void mergeMeasurements(Map samples, Meter meter) {
        meter.measure().forEach((measurement) -> samples.merge(measurement.getStatistic(), measurement.getValue(),
                mergeFunction(measurement.getStatistic())));
    }

    private static BiFunction mergeFunction(Statistic statistic) {
        return Statistic.MAX.equals(statistic) ? Double::max : Double::sum;
    }

    private static void mergeAvailableTags(Map> availableTags, Meter meter) {
        meter.getId().getTags().forEach((tag) -> {
            Set value = Collections.singleton(tag.getValue());
            availableTags.merge(tag.getKey(), value, MeterRegistryUtil::merge);
        });
    }

    private static  Set merge(Set set1, Set set2) {
        Set result = new HashSet<>(set1.size() + set2.size());
        result.addAll(set1);
        result.addAll(set2);
        return result;
    }

}