Is there a way to "wake up" a coroutine that is cu...

# coroutines

[richodemus]

Is there a way to "wake up" a coroutine that is currently suspended due to having called delay
so like this:

launch {
   println("This is called right away")
   delay(1, YEARS)
   println("I want this to happen when a criteria is met")
}

if(criteria) {
  cancelDelay()
}

[marstran]

Instead of delaying, you should use an actor. You can send a message to it when you meet your criteria.

[richodemus]

This question is specific to delay or something that handles very similar

[richodemus]

I want to suspend my coroutine and unsuspend it on command

[Seri]

https://github.com/Kotlin/kotlinx.coroutines/blob/master/coroutines-guide.md#making-computation-code-cancellable

[marstran]

Yes, and that it exactly what an actor is useful for.

[Seri]

You can cancel the entire job, and catch the cancellation in a try/catch block

[marstran]

You can do this with an actor:

val ch = actor<Int> {
    println("This is called right away")

    // Suspends until there's a message on the channel
    val ping = channel.receive()

    println("I want this to happen when a criteria is met")
}

runBlocking {
    delay(1000)
    if (criteria) {
        ch.send(0)
    }
}

[bj0]

yea, if you want to delay until told to continue, a Channel fits best. An actor is one way to use a channel

[bj0]

if you only need to do it once, a CompletableDeferred is also an option

[gildor]

+1 to actor solution. But it’s not exactly what original code does: do something after delay. But you can easily implement this by running additional coroutine that trigger action with delay, like:

actor<Int> {
    println("This is called right away")
   launch(coroutineContext) {
       delay(1, YEARS)
       send(someActorData)
   }
  val ping = channel.receive()

    println("I want this to happen when a criteria is met")
}

[richodemus]

Thanks