TestEnhancedSwitch.java

package jdk19;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;

import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.stream.IntStream;

public class TestEnhancedSwitch
{
    public sealed interface Fruit
    {
        record Apple() implements Fruit {}
        record Peach() implements Fruit {}
        record Pear() implements Fruit {}
        record Grapes() implements Fruit {}
        record Cherries() implements Fruit {}
    }

    public static void main(String[] args)
            throws RunnerException
    {
        Options opt = new OptionsBuilder()
                .include(TestEnhancedSwitch.class.getSimpleName())
                .threads(4)
                .forks(1)
                .jvmArgs("--enable-preview")
                .build();

        new Runner(opt).run();
    }

    @State(Scope.Benchmark)
    public static class Data
    {
        public final List<Fruit> fruits;
        public final Map<Class<?>, AtomicInteger> counts = new ConcurrentHashMap<>();

        public Data()
        {
            ThreadLocalRandom random = ThreadLocalRandom.current();
            int qty = random.nextInt(1000, 2000);
            Class<?>[] permittedSubclasses = Fruit.class.getPermittedSubclasses();
            fruits = IntStream.range(0, qty)
                    .mapToObj(__ -> {
                        Class<?> clazz = permittedSubclasses[random.nextInt(permittedSubclasses.length)];
                        counts.computeIfAbsent(clazz, dummy -> new AtomicInteger());
                        try {
                            return (Fruit) clazz.getConstructor().newInstance();
                        }
                        catch (Exception e) {
                            throw new RuntimeException(e);
                        }
                    })
                    .toList();
        }
    }

    @Benchmark
    public void testEnhancedSwitch(Data data)
    {
        for (Fruit fruit : data.fruits) {
            switch (fruit) {
                case Fruit.Apple __ -> data.counts.get(Fruit.Apple.class).incrementAndGet();
                case Fruit.Cherries __ -> data.counts.get(Fruit.Cherries.class).incrementAndGet();
                case Fruit.Grapes __ -> data.counts.get(Fruit.Grapes.class).incrementAndGet();
                case Fruit.Peach __ -> data.counts.get(Fruit.Peach.class).incrementAndGet();
                case Fruit.Pear __ -> data.counts.get(Fruit.Pear.class).incrementAndGet();
            }
        }
    }

    @Benchmark
    public void testManualSwitch(Data data)
    {
        for (Fruit fruit : data.fruits) {
            if (fruit.getClass().equals(Fruit.Apple.class)) {
                data.counts.get(Fruit.Apple.class).incrementAndGet();
            }
            else if (fruit.getClass().equals(Fruit.Cherries.class)) {
                data.counts.get(Fruit.Cherries.class).incrementAndGet();
            }
            else if (fruit.getClass().equals(Fruit.Grapes.class)) {
                data.counts.get(Fruit.Grapes.class).incrementAndGet();
            }
            else if (fruit.getClass().equals(Fruit.Peach.class)) {
                data.counts.get(Fruit.Peach.class).incrementAndGet();
            }
            else if (fruit.getClass().equals(Fruit.Pear.class)) {
                data.counts.get(Fruit.Pear.class).incrementAndGet();
            }
        }
    }
}

Benchmark                               Mode  Cnt      Score       Error  Units
TestEnhancedSwitch.testEnhancedSwitch  thrpt    5  30789.482 ± 17667.365  ops/s
TestEnhancedSwitch.testManualSwitch    thrpt    5  44651.612 ±  5135.641  ops/s

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