Disclaimer: not an expert
Question
I didn’t see any where the async is required to time out after a certain time
frame. I would think that we would want to specify both on the function
declaration side as a default and on the function call side as a customization.
That being said, the return time then becomes an optional given the timeout and
the calling code would need to unwrap.
func loadWebResource(_ path: String) async -> Resource
func decodeImage(_ r1: Resource, _ r2: Resource) async -> Image
func dewarpAndCleanupImage(_ i : Image) async -> Image
func processImageData1() async -> Image {
let dataResource = await loadWebResource("dataprofile.txt")
let imageResource = await loadWebResource("imagedata.dat")
let imageTmp = await decodeImage(dataResource, imageResource)
let imageResult = await dewarpAndCleanupImage(imageTmp)
return imageResult
}
So the prior code becomes…
func loadWebResource(_ path: String) async(timeout: 1000) -> Resource?
func decodeImage(_ r1: Resource, _ r2: Resource) async -> Image?
func dewarpAndCleanupImage(_ i : Image) async -> Image?
func processImageData1() async -> Image? {
let dataResource = guard let await loadWebResource("dataprofile.txt”) else
{ // handle timeout }
let imageResource = guard let await(timeout: 100)
loadWebResource("imagedata.dat”) else { // handle timeout }
let imageTmp = await decodeImage(dataResource, imageResource)
let imageResult = await dewarpAndCleanupImage(imageTmp)
return imageResult
}
Given this structure, the return type of all async’s would be optionals with
now 3 return types??
.continuation // suspends and picks back up
.value // these are the values we are looking for
.none // took too long, so you get nothing.
> On 2017-Aug -17 (34), at 18:24, Chris Lattner via swift-evolution
> <[email protected]> wrote:
>
> Hi all,
>
> As Ted mentioned in his email, it is great to finally kick off discussions
> for what concurrency should look like in Swift. This will surely be an epic
> multi-year journey, but it is more important to find the right design than to
> get there fast.
>
> I’ve been advocating for a specific model involving async/await and actors
> for many years now. Handwaving only goes so far, so some folks asked me to
> write them down to make the discussion more helpful and concrete. While I
> hope these ideas help push the discussion on concurrency forward, this isn’t
> in any way meant to cut off other directions: in fact I hope it helps give
> proponents of other designs a model to follow: a discussion giving extensive
> rationale, combined with the long term story arc to show that the features
> fit together.
>
> Anyway, here is the document, I hope it is useful, and I’d love to hear
> comments and suggestions for improvement:
> https://gist.github.com/lattner/31ed37682ef1576b16bca1432ea9f782
>
> -Chris
>
> _______________________________________________
> swift-evolution mailing list
> [email protected]
> https://lists.swift.org/mailman/listinfo/swift-evolution
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