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#multiplatform
Title
# multiplatform
j
John O'Reilly
08/12/2020, 6:08 PMI'm trying out the new 1.4 capability of being able to call
suspendthis is example of function I'm trying to call (currently called by Android client)
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suspend fun fetchNetworkList() : Map<String, List<Network>> {
val result = cityBikesApi.fetchNetworkList()
return result.networks.groupBy { it.location.country }
}(
cityBikesApi.fetchNetworkList()And up to now have been calling following from iOS
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fun fetchNetworkList(success: (Map<String, List<Network>>) -> Unit) {
ktorScope {
success(fetchNetworkList())
}
}ktorScopeGlobalScope.launch(Dispatchers.Main)runBlockingnative-mtif call suspend function directly from iOS I'm getting following errors
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<https://api.citybik.es/v2/networks/galway> failed with exception: kotlin.native.concurrent.InvalidMutabilityException: mutation attempt of frozen io.ktor.client.call.HttpClientCall@30bde68but if I add following
withContext Copy code
suspend fun fetchNetworkList() : Map<String, List<Network>> {
return withContext(Dispatchers.Main) {
val result = cityBikesApi.fetchNetworkList()
result.networks.groupBy { it.location.country }
}
}In either case I am calling the
suspendr
russhwolf
08/12/2020, 6:39 PMHmm. I should stop guessing it's the main-thread thing because I've been wrong every time
Not sure what else, though. Probably a ktor thing like Kevin was suggesting on Twitter but I don't have any better insight
j
John O'Reilly
08/12/2020, 6:40 PMYeah, the interworking of ktor and native-mt version of kotlinx coroutines is somewhat of an unknown right now....perhaps have been lucky that it's worked in so far as it has up to now
r
russhwolf
08/12/2020, 6:40 PMYou could try building a similar structure without native-mt coroutines and see if that still causes trouble
j
John O'Reilly
08/12/2020, 6:42 PMwhat's strange is that it works with that
withContext(Dispatchers.Main)k
Kris Wong
08/12/2020, 6:46 PMktor doesn't support native-mt. there are certain conditions under which it happens to work, but it's quite brittle.
it has to do with whether certain ktor internal state gets frozen or not by the runtime
j
John O'Reilly
08/12/2020, 6:49 PMyeah, I think I'm going to have to realistically wait until that's sorted before progressing any further with this
r
russhwolf
08/12/2020, 6:51 PMYeah I'm hoping we get news there on the ktor front soon but haven't seen/heard anything yet. If it's becoming an issue you might be better off returning to standard coroutines for the time being
We don't have all the KaMPKit dependencies ready for 1.4 yet, but once we do I'd like to try updating that project and see if we hit something similar.
j
John O'Reilly
08/12/2020, 6:52 PMCan probably do that in this particular repo but in others I'm using SQLDelight which I believe depends on use of
native-mtat least I think it does for flow support that was added a little while back
r
russhwolf
08/12/2020, 6:53 PMYes it does. If you don't include that module I think you'd be ok
k
Kris Wong
08/12/2020, 7:34 PMthis is a primary reason I dropped ktor
you can create your own HttpClient class (at least for Android and iOS) in a matter of an hour or two
vs. spending days trying to get ktor working
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k
kpgalligan
08/13/2020, 9:05 PMWe’re not using ktor on client work until that’s resolved. To be precise, you can use mt coroutines with ktor, as long as the Job that’s part of the scope you’re in doesn’t get frozen. Effectively that means you either have a separate ktor scope, or do something complicated like we did with KaMP Kit. Neither is fun. Star this issue: https://youtrack.jetbrains.com/issue/KTOR-499
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