I'm looking through through Kotlin Coroutines - Co...

# coroutines

[Alexandru Hadăr]

I'm looking through through Kotlin Coroutines - Continuation and something doesn't seem to make sense.
Let's say we have the function:

suspend fun printId() {
    val id = getId() // suspend fun getId(): String
    saveId(id) // private suspend fun saveId(id: String)
    println("Your id is: $id")
}

Roughly, translated by the compiler it would look like:

fun printId(continuation: Continuation<*>) {

    val result : Result<Any>? = continuation.result
    when (continuation.label) {
        0 -> {
            continuation.label = 1
            val res = getId(continuation)
            if (res == COROUTINE_SUSPENDED) {
                return COROUTINE_SUSPENDED
            }
            result = Result.success(res)
        }
        1 -> {
            ...
        }
    }
}

What I don't understand is when will result = Result.success(res) ever be called?

From what I can tell:
• label is already 1, so when the continuation's resumeWith inside getUserId will be called will go directly to 1
• otherwise, getId could only return COROUTINE_SUSPENDED , because will move the function to another thread;
Could it be when the we don't use a dispatcher inside getId, so everything is on the same thread? Any other cases?

[ephemient]

are you following https://github.com/JetBrains/kotlin/blob/master/compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/coroutines-codegen.md ?

[Alexandru Hadăr]

never knew of such file. Could be a great starting point.
Thank you!