Let's start a thread on how to use Ktor `HttpClient` in a `Worker` (background thread) on native :sl...

# ktor

[Marc Knaup]

Let's start a thread on how to use Ktor HttpClient in a Worker (background thread) on native 🙂

[Marc Knaup]

Workaround for https://github.com/JetBrains/kotlin-native/issues/3061
Use TransferMode.UNSAFE to move(!) the HttpClient instance to your Worker. Unless you create it directly within the worker in which case this is not necessary. In both cases it is stored in an @ThreadLocal variable.

worker.execute(TransferMode.UNSAFE, { HttpClient(Ios) }) { httpClient -> threadLocalHttpClient = httpClient }

[Marc Knaup]

Launch the coroutine for executing HttpClient calls inside your Worker.

GlobalScope.launch(Dispatchers.Unconfined) {
	// use HttpClient
}

[Marc Knaup]

Workaround for https://github.com/Kotlin/kotlinx-io/issues/53

body = TextContent(
	text = someJson,
	contentType = ContentType.Application.Json
)

->

body = ByteArrayContent(
	bytes = someJson.toUtf8(),
	contentType = ContentType.Application.Json
)

[Marc Knaup]

You cannot create a HttpClient instance on a non-main thread until this is fixed:
https://github.com/ktorio/ktor/issues/1183

There may be more of such issue though.

[Marc Knaup]

NSURLSession responds on the main thread and the coroutine continues on that thread due to Unconfined 😞

Is there a better way of getting the coroutine execution back into the Worker rather than using worker.execute(TransferMode.UNSAFE, …)?

[e5l]

It looks like that problem can be solved by moving constants(and it fixed in the ios support branch). The next big problem is unfrozen values in atomicfu primitives and it can't be solved on ktor side for now.