DispatcherBenchmarks.kt

package kotlinx.coroutines.benchmarks
/*
 * Copyright 2016-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
 */

import kotlinx.coroutines.*
import kotlinx.coroutines.channels.*
import org.jetbrains.gradle.benchmarks.*
import kotlin.js.*
import kotlin.random.*

const val batchSize = 15

abstract class BenchmarkBase(private val dispatcher: CoroutineDispatcher) {
    private var data = 0.0

    @Setup
    fun setUp() {
        data = Random.nextDouble()
    }

    @Benchmark
    fun asyncAsPromise(): Promise<Double> {
        return GlobalScope.async(dispatcher) {
            data
        }.asPromise()
    }

    @Benchmark
    fun asyncYields(): Promise<Double> {
        return GlobalScope.async(dispatcher) {
            repeat(batchSize - 1) {
                yield()
            }

            data
        }.asPromise()
    }

    @Benchmark
    fun bridgeResolveBenchmark(): Promise<Double> {
        val channel = Channel<Unit>(batchSize + 1)
        require(channel.offer(Unit))
        return GlobalScope.async(dispatcher) {
            repeat(batchSize) {
                channel.receive()
                Promise.resolve(data).then {
                    require(channel.offer(Unit))
                }
            }

            data
        }.asPromise()
    }

    @Benchmark
    fun bridgeSetTimeoutBenchmark(): Promise<Double> {
        val channel = Channel<Unit>(batchSize + 1)
        require(channel.offer(Unit))
        return GlobalScope.async(dispatcher) {
            repeat(batchSize) {
                channel.receive()
                setTimeout({
                    require(channel.offer(Unit))

                }, 0)
            }

            data
        }.asPromise()
    }
}

@State(Scope.Benchmark)
class ResolveBenchmark : BenchmarkBase(ResolveDispatcher)

@State(Scope.Benchmark)
class SetTimeoutBenchmark : BenchmarkBase(SetTimeoutDispatcher)

@State(Scope.Benchmark)
class MessageQueueBenchmark : BenchmarkBase(Dispatchers.Default)

Dispatchers.kt

/*
 * Copyright 2016-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
 */

package kotlinx.coroutines.benchmarks

import kotlinx.coroutines.*
import kotlin.coroutines.*
import kotlin.js.*

public object ResolveDispatcher : CoroutineDispatcher() {
    override fun dispatch(context: CoroutineContext, block: Runnable) {
        Promise.resolve(Unit).then { block.run() }
    }
}

public object SetTimeoutDispatcher : CoroutineDispatcher() {
    override fun dispatch(context: CoroutineContext, block: Runnable) {
        setTimeout({
            block.run()
        }, 0)
    }
}

public external fun setTimeout(handler: dynamic, timeout: Int = definedExternally): Int