Kotlin协程的启动方式介绍

fun testGlobalScope() {
    GlobalScope.launch {
        println("Coroutinue started!")
        delay(1000L)
        println("Hello World!")
    }
    println("After launch!")
    Thread.sleep(2000L)
    println("Process end!")
}

@DelicateCoroutinesapi
public object GlobalScope : CoroutineScope {
    
    override val coroutineContext: CoroutineContext
        get() = EmptyCoroutineContext
}

public fun CoroutineScope.launch(
    context: CoroutineContext = EmptyCoroutineContext,
    start: CoroutineStart = CoroutineStart.DEFAULT,
    block: suspend CoroutineScope.() -> Unit
): Job {
    val newContext = newCoroutineContext(context)
    val coroutine = if (start.isLazy)
        LazyStandaloneCoroutine(newContext, block) else
        StandaloneCoroutine(newContext, active = true)
    coroutine.start(start, coroutine, block)
    return coroutine
}

fun testRunBlocking2() {
    runBlocking {
        println("Coroutinue started!")
        delay(1000L)
        println("Hello World!")
    }
    println("After Launch")
    Thread.sleep(2000L)
    println("Process end")
}

@Throws(InterruptedException::class)
public actual fun <T> runBlocking(context: CoroutineContext, block: suspend CoroutineScope.() -> T): T {
    contract {
        callsInPlace(block, InvocationKind.EXACTLY_ONCE)
    }
    val currentThread = Thread.currentThread()
    val contextInterceptor = context[ContinuationInterceptor]
    val eventLoop: EventLoop?
    val newContext: CoroutineContext
    if (contextInterceptor == null) {
        // create or use private event loop if no dispatcher is specified
        eventLoop = ThreadLocalEventLoop.eventLoop
        newContext = GlobalScope.newCoroutineContext(context + eventLoop)
    } else {
        // See if context's interceptor is an event loop that we shall use (to support TestContext)
        // or take an existing thread-local event loop if present to avoid blocking it (but don't create one)
        eventLoop = (contextInterceptor as? EventLoop)?.takeIf { it.shouldBeProcessedFromContext() }
            ?: ThreadLocalEventLoop.currentOrNull()
        newContext = GlobalScope.newCoroutineContext(context)
    }
    val coroutine = BlockinGCoroutine<T>(newContext, currentThread, eventLoop)
    coroutine.start(CoroutineStart.DEFAULT, coroutine, block)
    return coroutine.joinBlocking()
}

fun testRunBlocking() {
    val runBlockingResult = runBlocking {
        delay(500L)
        return@runBlocking "HaHa"
    }
    println("result:$runBlockingResult")
}
result:HaHa

fun testAsync() {
    runBlocking {
        val deferred = async {
            println("do async:${Thread.currentThread().name}")
            delay(1000L)
            return@async "do completed"
        }
        println("After async:${Thread.currentThread().name}")
        val result = deferred.await()
        println("Result is: $result")
    }
}
After async:main @coroutine#1
do async:main @coroutine#2
Result is: do completed

public fun <T> CoroutineScope.async(
    context: CoroutineContext = EmptyCoroutineContext,
    start: CoroutineStart = CoroutineStart.DEFAULT,
    block: suspend CoroutineScope.() -> T
): Deferred<T> {
    val newContext = newCoroutineContext(context)
    val coroutine = if (start.isLazy)
        LazyDeferredCoroutine(newContext, block) else
        DeferredCoroutine<T>(newContext, active = true)
    coroutine.start(start, coroutine, block)
    return coroutine
}