Hi guys. I’m writing a multiplatform app with network calls and coroutines. I have basically two Co...

# multiplatform

[alexfacciorusso]

Hi guys. I’m writing a multiplatform app with network calls and coroutines.

I have basically two Coroutine Dispatchers, one for main and one for i/o operations. On Android, these are defined as Dispatchers.Main and Dispatchers.IO.

On iOS, though, I’ve implemented what I’ve seen on many projects/tutorials online: a custom dispatch_queue dispatcher that takes a native dispatch queue and calls a dispatch_async() on it.

The tutorials I’ve seen, though, they use the same dispatch queue for running every operation (the main dispatch queue). Indeed if I try to create a new dispatch queue for network (a new thread), it says it can’t run stuff in it because it can’t use a “non blocked or shared object” on a different thread.

Questions:
1. Is there a way to create two threads for two dispatchers and use them with coroutines in Kotlin MPP (I think not, since I’m seeing that there’s an issue filed for it);
2. How bad is running network and UI in the same thread but asyncronously?
3. Are there some limitations for this?

[kpgalligan]

1. No

[kpgalligan]

2. That’s what ktor does

[kpgalligan]

Network calls are async, and coroutine continues in main thread when async call completes

[alexfacciorusso]

Thank you very much, now I’m relieved about it 😅

[kpgalligan]

3. For async and continue? No real limitation, other than managing your own async. I have a pending blog post about this…

[kpgalligan]

I have a simple suspend function here https://github.com/touchlab/DroidconKotlin/blob/master/sessionize/lib/src/commonMain/kotlin/co/touchlab/sessionize/platform/Functions.kt#L13

[kpgalligan]

You call that from the main thread, give it a lambda (which will be frozen, so be careful), and it’ll suspend and run that in a background thread. When complete, it’ll continue in the main thread

[kpgalligan]

Have another threading mechanism here. Listens for db updates here https://github.com/touchlab/DroidconKotlin/blob/master/sessionize/lib/src/commonMain/kotlin/co/touchlab/sessionize/platform/Functions.kt#L13

[kpgalligan]

Pushes to main thread here https://github.com/touchlab/DroidconKotlin/blob/master/sessionize/lib/src/commonMain/kotlin/co/touchlab/sessionize/architecture/MainThreadPubSub.kt

[kpgalligan]

All of this goes away when multithreaded coroutines happen

[kpgalligan]

First 2 parts of threading series, while we’re talking about it https://medium.com/@kpgalligan/kotlin-native-stranger-threads-ep-1-1ccccdfe0c99

[alexfacciorusso]

That’s very nice, looking forward to reading the new article when you’ll finish it! 😁