I’m trying to understand

Continuation

in detail. Can someone recommend some good resources on the topic?

Hey guys, So I have a server class which contains a map of strings to bots, and theres this function in the server class called runBots() which run all the bots. This is what I have for a implementation:

fun runBots() = runBlocking {
        try {
            bots.forEach {
                val one = launch { it.value.setConnection(); }
                one.join()
                delay(3000L)
                if(it.value.running) {
                    it.value.Connect()
                }
            }
        } catch(e: Throwable) {
            bots.forEach { if(!it.value.running) it.value.Connect() }
        }
    }

"bots" here is the map of strings to bots. Each bot has a Connect() function(a async function) which runs the all the bot's main loop. The problem is that the bot doesnt run, after the server class calls it's runBots function.

Initialised
Connnected: true
Defined bot
Added bot
[main] Connecting....
[main] Sending nick...
Sending nick: NICK Kraken3635

[main] Sending user...
Sending user: USER Nani 0 * :Nani

[main] Connected!
[DefaultDispatcher-worker-1] I'm now in Connect!
[DefaultDispatcher-worker-1] Entering loop...

I like the convention about

CoroutineScope

extensions, but I think it should be also in docs

I don't see any safely issues with the first. But you cannot use first approach in some cases. For example you cannot use it for Android Fragments when Job can be recreated

I am getting <undefinedtype> from suspend block when I looked into the ByteCode Viewer. https://gist.github.com/iNoles/6df55f2244b02f781a480a5a2b978544

suspend fun addEvent(value: MsgType): Event {
    val eventChannel = Channel<Event>()
    var event: Event? = null

    log("joining", logMessages)
    if (value == MsgType.ping) {
        log("ping", logMessages)
        eventChannel.send(PingEvent(value) as Event)
    }
    else if (value == MsgType.join) {
        log("join", logMessages)
        eventChannel.send(JoinEvent(value) as Event)
    }
    else if (value == MsgType.normal) {
        log("normal", logMessages)
        eventChannel.send(NormalEvent(value) as Event)
    }
    else if (value == MsgType.privmsg) {
        log("privmsg", logMessages)
        eventChannel.send(PrivMsgEvent(value) as Event)
    }
    else if (value == MsgType.mode) {
        log("mode", logMessages)
        eventChannel.send(ModeEvent(value) as Event)
    }
    else if (value == MsgType.notice) {
        log("notice", logMessages)
        eventChannel.send(NoticeEvent(value) as Event)
    }
    else if (value == MsgType.special) {
        log("special", logMessages)
        eventChannel.send(SpecialEvent(value) as Event)
    }
    else if (value == MsgType.namelist) {
        log("namelist", logMessages)
        eventChannel.send(NameListEvent(value) as Event)
    }
    else if (value == MsgType.topic) {
        log("topic", logMessages)
        eventChannel.send(TopicEvent(value) as Event)
    }
    else if (value == MsgType.topic_whotime) {
        log("whotime", logMessages)
        eventChannel.send(TopicWhoTimeEvent(value) as Event)
    }
    else if (value == MsgType.quit) {
        log("quit", logMessages)
        eventChannel.send(QuitEvent(value) as Event)
    }
    else if (value == MsgType.who) {
        log("who", logMessages)
        eventChannel.send(WhoEvent(value) as Event)
    }
    else if (value == MsgType.end_of_who) {
        log("end of who", logMessages)
        eventChannel.send(EndOfWhoEvent(value) as Event)
    }

    log("receiving", logMessages)
    event = eventChannel.receive()

    log("received", logMessages)
    if(event == null)
        throw AghoraException("Error: In addEvent(value: MsgType): Event in " +
        " com.github.otakusenpai.aghora.irc: No implementation of MsgType ${value.toString()}")

    log("returning", logMessages)
    return event
}

Can anyone explain why this code isnt returning the value from the Channel ?

I was thinking to parse some pdf's and for each file to create a new coroutine, but after that I've stop

I will be very happy for some links, any links 🙂

Is there a standard way to skip a select clause for a closed channel?

onReceiveOrNull

doesn't really work if I have multiple channels and want the rest to continue if any of them close (as

select

is biased to the first).

Also wondering if there's new versions of examples here: https://github.com/Kotlin/kotlin-coroutines/tree/master/examples which seem to be 2 years old now?

Is there a way to say "give me the coroutine context if I am in a coroutine"? I basically want/need a way to detect if I am running in a coroutine and to grab the context, even in a non suspending method. It that possible?

What's the best way to track metrics of the rate at which items are flowing through channels? I could do it at each consumer/receiver but if you have more than one then you have to aggregate somehow

What about using

class MainPresenter : CoroutineScope by CoroutineScope(Dispatchers.Main)

to get rid of a bit of boilerplate, just missing an easy way to access its Job to cancel it on the end of its lifecycle...?

Is it possible to know how many messages are waiting for an actor to process?

So I'm fooling around with sleepsort to try how I can make channels and sequences interact:

suspend fun main(args: Array<String>) = runBlocking {

    val unsorted = generateSequence { Random.nextInt() }.take(200)
    val sortedChannel = Channel<Int>()
    val sorted = sequence { for (msg in sortedChannel) yield(msg) }
    unsorted.map { async { delay(it * 10L); sortedChannel.send(it) } }
    sorted.forEach(::println)
}

But I'm getting an error about restricted suspending functions where I'm iterating over the channel. Can anyone tell me what that's about?

Hey guys, I’m trying to understand `Job`’s

cancel

method. I’m working on creating a class that implements

CoroutineScope

and I’m following the example here https://github.com/Kotlin/kotlinx.coroutines/blob/master/core/kotlinx-coroutines-core/test/guide/example-context-10.kt. I would expect that

job.cancel()

would return true in this case since the invocation of cancel is what cancels the job, however, when I print the result of

job.cancel()

I get false.

fun destroy() {
     val temp = job.cancel()
     print(temp.toString()) //prints "false" even though I would expect it to print "true"
}

Am I misunderstanding cancel?

Once the 1.0 version of the coroutines library is released, would it be possible to include it as a dependency from play.kotlinlang.org? It would be really handy to be able to share code sketches to demonstrate coroutines usage.

hey, qq on exception handling. How do I make coroutine stop if a child coroutine throws an exception:

launch {
            launch {
                throw RuntimeException()
            }
            while (true) {
                println("123123")
            }
        }

I want parent launch to exit with an exception, but not sure how to

I just watched the coroutine talk about creating a service that takes in locations, fetches content for new locations, and then reuses contents if a location has already been fetched: Over there, it looks like if any content fetching fails, the entire service is cancelled. How do we make it so that failing a content fetch will only cancel requests based on that particular location? The docs look like any exception beyond

CancellationException

will cancel the parent no matter what, so do we have to wrap our code in a try catch? To be more specific, this is the problem I want to solve: I have a method that takes in an id and returns an auth object I have other methods that will take in an auth object and then output something else I want to create a running stream for the duration of my lifecycle that will take in ids and actions. If an auth does not exist (say in a map), I want to fetch it. Once an auth is fetched, I want to run any pending actions on that auth. If an auth is being fetched and another request is made requiring that auth, it should wait for the previous fetch rather than getting a new auth itself. This pattern is already shown in the talk using

Map<T, List<K>>

. If the auth fetch fails, I want to cancel any pending actions. If an action fails, or anything else outside of this scope, I want the

CoroutineScope

to stay alive, until it is cancelled by the lifecycle.

This message was deleted.

Is simply assuming its OK to dispatch things on the common pool an OK practice? What about the default executor?

the typical java answer would be to expose `ExecutorService`'s at API entry points, but that seems like a clooge, at so should I simply expose `CoroutineDispatcher`s in the same vein? Should I fetch them off the callers

scope

?

java.lang.IllegalStateException: Module with the Main dispatcher is missing. Add dependency providing the Main dispatcher

release builds only

Do you know where I could found a bigger version of the suspend logo? (for a presentation)

❓ What is supposed to happen if

async {}

block throws an exception, but the result is never used? I get different behaviour in playground and InteliJ https://pl.kotl.in/rkOAdiNiQ

suspend fun main() {
    coroutineScope {
        val x = async { null!! }
    }
    
    println("end")
}

Hey 🙂 Quick stupid question. When you’re in a coroutine and call a blocking java function (like a guava future’s get method) does it block the whole thread? I’d say yes but then how do you handle libraries that use that kind of future internally?

I had a similar question I’ve been meaning to ask - I’m working with a third party library that has a blocking call - it’s non-cpu intensive (just a really basic subscription) - but I am unsure of the best way to allow many of these subscriptions to run at the same time with co-routines

Thanks @louiscad, so would it be a good solution to wrap the calls in what @enleur suggested here -> https://kotlinlang.slack.com/archives/C1CFAFJSK/p1539784566000100?thread_ts=1539784399.000100&amp;cid=C1CFAFJSK ?

Does anyone have a link to the code from Roman's recent talk on coroutines?