Kotlin协程launch原理详解

fun main() {
    val coroutineScope = CoroutineScope(Job())
    coroutineScope.launch {
        println("1969年 叶文洁进入红岸基地")
        println("1971年 红岸基地，叶文洁第一次向太阳发送信号，但未发现回波")
        delay(4000L)
        println("1975年 半人马座三星，三体世界得知地球存在")
    }
    Thread.sleep(5000L)
}

public final class LaunchTestKt {
    public static final void main() {
        Job unused = BuildersKt__Builders_commonKt.launch$default(CoroutineScopeKt.CoroutineScope(JobKt.Job$default((Job) null, 1, (Object) null)), (CoroutineContext) null, (CoroutineStart) null, new LaunchTestKt$main$1((Continuation<? super LaunchTestKt$main$1>) null), 3, (Object) null);
        Thread.sleep(5000);
    }
}
final class LaunchTestKt$main$1 extends SuspendLambda implements Function2<CoroutineScope, Continuation<? super Unit>, Object> {
    int label;
    LaunchTestKt$main$1(Continuation<? super LaunchTestKt$main$1> continuation) {
        super(2, continuation);
    }
    public final Continuation<Unit> create(Object obj, Continuation<?> continuation) {
        return new LaunchTestKt$main$1(continuation);
    }
    public final Object invoke(CoroutineScope coroutineScope, Continuation<? super Unit> continuation) {
        return ((LaunchTestKt$main$1) create(coroutineScope, continuation)).invokeSuspend(Unit.INSTANCE);
    }
    public final Object invokeSuspend(Object $result) {
        Object coroutine_suspended = IntrinsicsKt.getCOROUTINE_SUSPENDED();
        switch (this.label) {
            case 0:
                ResultKt.throwOnFailure($result);
                System.out.println("1969年 叶文洁进入红岸基地");
                System.out.println("1971年 红岸基地，叶文洁第一次向太阳发送信号，但未发现回波");
                this.label = 1;
                if (DelayKt.delay(4000, this) != coroutine_suspended) {
                    break;
                } else {
                    return coroutine_suspended;
                }
            case 1:
                ResultKt.throwOnFailure($result);
                break;
            default:
                throw new IllegalStateException("call to 'resume' before 'invoke' with coroutine");
        }
        System.out.println("1975年 半人马座三星，三体世界得知地球存在");
        return Unit.INSTANCE;
    }
}

public fun CoroutineScope.launch(
    context: CoroutineContext = EmptyCoroutineContext,
    start: CoroutineStart = CoroutineStart.DEFAULT,
    block: suspend CoroutineScope.() -> Unit
): Job {
    //代码1
    val newContext = newCoroutineContext(context)
    //代码2
    val coroutine = if (start.isLazy)
        LazyStandaloneCoroutine(newContext, block) else
        StandaloneCoroutine(newContext, active = true)
    //代码3
    coroutine.start(start, coroutine, block)
    return coroutine
}

private open class StandaloneCoroutine(
    parentContext: CoroutineContext,
    active: Boolean
) : AbstractCoroutine<Unit>(parentContext, initParentJob = true, active = active) {
    override fun handleJobException(exception: Throwable): Boolean {
        handleCoroutineException(context, exception)
        return true
    }
}
public abstract class AbstractCoroutine<in T>(
    parentContext: CoroutineContext,
    initParentJob: Boolean,
    active: Boolean
) : JobSupport(active), Job, Continuation<T>, CoroutineScope {
    public fun <R> start(start: CoroutineStart, receiver: R, block: suspend R.() -> T) {
        start(block, receiver, this)
    }
}

public enum class CoroutineStart {
    DEFAULT,
    LAZY,
    ATOMIC,
    UNDISPATCHED;
    public operator fun <R, T> invoke(block: suspend R.() -> T, receiver: R, completion: Continuation<T>): Unit =
        when (this) {
            DEFAULT -> block.startCoroutineCancellable(receiver, completion)
            ATOMIC -> block.startCoroutine(receiver, completion)
            UNDISPATCHED -> block.startCoroutineUndispatched(receiver, completion)
            LAZY -> Unit // will start lazily
        }
    public val isLazy: Boolean get() = this === LAZY
}

public fun <T> (suspend () -> T).startCoroutineCancellable(completion: Continuation<T>): Unit = runSafely(completion) {
    createCoroutineUnintercepted(completion).intercepted().resumeCancellableWith(Result.success(Unit))
}
public actual fun <T> (suspend () -> T).createCoroutineUnintercepted(
    completion: Continuation<T>
): Continuation<Unit> {
    val probeCompletion = probeCoroutineCreated(completion)
    return if (this is BaseContinuationImpl)
        //走这里
        create(probeCompletion)
    else
        createCoroutineFromSuspendFunction(probeCompletion) {
            (this as Function1<Continuation<T>, Any?>).invoke(it)
        }
}