FlowComparison.java

package io.reactivex;

import java.util.concurrent.*;

import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.infra.Blackhole;

import io.reactivex.internal.util.Pow2;
import io.reactivex.schedulers.Schedulers;
import io.reactivex.subjects.PublishSubject;
import java8.util.concurrent.*;
import java8.util.concurrent.Flow.Subscription;

@BenchmarkMode(Mode.Throughput)
@Warmup(iterations = 5)
@Measurement(iterations = 5, time = 5, timeUnit = TimeUnit.SECONDS)
@OutputTimeUnit(TimeUnit.SECONDS)
@Fork(value = 1)
@State(Scope.Thread)
public class FlowComparison {
    @Param({ "1", "1000", "1000000" })
    public int times;
    
    Observable<Integer> rxRange;
    
    ExecutorService exec;

    int capacity;
    
    @Setup
    public void setup() {
        capacity = Math.max(Pow2.roundToPowerOfTwo(times), 256);

        rxRange = Observable.range(1, times).observeOn(Schedulers.single());
        
        exec = Executors.newSingleThreadExecutor();
    }
    
    
    @TearDown
    public void teardown() {
        exec.shutdownNow();
    }
    
    @Benchmark
    public void rxFirehose(Blackhole bh) throws Exception {
        int s = times;
        LatchedObserver<Integer> lo = new LatchedObserver<>(bh);

        PublishSubject<Integer> rxSubject = PublishSubject.create();
        rxSubject.observeOn(Schedulers.single(), false, capacity).subscribe(lo);
        
        for (int i = 0; i < s; i++) {
            rxSubject.onNext(i);
        }
        rxSubject.onComplete();
        
        lo.latch.await();
    }
    
    @Benchmark
    public void spFirehose(Blackhole bh) throws Exception {
        int s = times;
        FlowLatchedObserver<Integer> lo = new FlowLatchedObserver<>(bh);
        SubmissionPublisher<Integer> spReceive = new SubmissionPublisher<>(exec, capacity);
        spReceive.subscribe(lo);
        
        for (int i = 0; i < s; i++) {
            spReceive.submit(i);
        }
        spReceive.close();
        
        lo.latch.await();
    }
    
    @Benchmark
    public void rxRange(Blackhole bh) throws Exception {
        LatchedObserver<Integer> lo = new LatchedObserver<>(bh);

        rxRange.subscribe(lo);
        
        lo.latch.await();
    }
    
    @Benchmark
    public void spRange(Blackhole bh) throws Exception {
        int s = times;
        FlowLatchedObserver<Integer> lo = new FlowLatchedObserver<>(bh);
        SubmissionPublisher<Integer> spRange = new SubmissionPublisher<>(exec, Observable.bufferSize());
        spRange.subscribe(lo);
        
        for (int i = 0; i < s; i++) {
            spRange.submit(i);
        }
        spRange.close();
        
        lo.latch.await();
    }
    
    
    static final class FlowLatchedObserver<T> implements Flow.Subscriber<T> {

        public CountDownLatch latch = new CountDownLatch(1);
        private final Blackhole bh;

        public FlowLatchedObserver(Blackhole bh) {
            this.bh = bh;
        }

        @Override
        public void onComplete() {
            latch.countDown();
        }

        @Override
        public void onError(Throwable e) {
            latch.countDown();
        }

        @Override
        public void onNext(T t) {
            bh.consume(t);
        }

        @Override
        public void onSubscribe(Subscription subscription) {
            subscription.request(Long.MAX_VALUE);
        }
        
    }
}