Code/net/minecraft/util/profiling/jfr/stats/GcHeapStat.java

package net.minecraft.util.profiling.jfr.stats;

import java.time.Duration;
import java.time.Instant;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import jdk.jfr.consumer.RecordedEvent;

public record GcHeapStat(Instant timestamp, long heapUsed, GcHeapStat.Timing timing) {
    public static GcHeapStat from(RecordedEvent p_185698_) {
        return new GcHeapStat(
            p_185698_.getStartTime(),
            p_185698_.getLong("heapUsed"),
            p_185698_.getString("when").equalsIgnoreCase("before gc") ? GcHeapStat.Timing.BEFORE_GC : GcHeapStat.Timing.AFTER_GC
        );
    }

    public static GcHeapStat.Summary summary(Duration p_185691_, List<GcHeapStat> p_185692_, Duration p_185693_, int p_185694_) {
        return new GcHeapStat.Summary(p_185691_, p_185693_, p_185694_, calculateAllocationRatePerSecond(p_185692_));
    }

    private static double calculateAllocationRatePerSecond(List<GcHeapStat> p_185696_) {
        long i = 0L;
        Map<GcHeapStat.Timing, List<GcHeapStat>> map = p_185696_.stream().collect(Collectors.groupingBy(p_185689_ -> p_185689_.timing));
        List<GcHeapStat> list = map.get(GcHeapStat.Timing.BEFORE_GC);
        List<GcHeapStat> list1 = map.get(GcHeapStat.Timing.AFTER_GC);

        for (int j = 1; j < list.size(); j++) {
            GcHeapStat gcheapstat = list.get(j);
            GcHeapStat gcheapstat1 = list1.get(j - 1);
            i += gcheapstat.heapUsed - gcheapstat1.heapUsed;
        }

        Duration duration = Duration.between(p_185696_.get(1).timestamp, p_185696_.get(p_185696_.size() - 1).timestamp);
        return (double)i / duration.getSeconds();
    }

    public record Summary(Duration duration, Duration gcTotalDuration, int totalGCs, double allocationRateBytesPerSecond) {
        public float gcOverHead() {
            return (float)this.gcTotalDuration.toMillis() / (float)this.duration.toMillis();
        }
    }

    static enum Timing {
        BEFORE_GC,
        AFTER_GC;
    }
}