fecth response callback called with 'cancelled' flag but not the 'finished' one

[guillaumeblanc]

Hi,

I modified sokol fetch unit tests to reproduce a functional behavior that doesn't match with documentation. When sfetch_cancel is called between sfetch_send and sfetch_dowork, then the response callback is called with cancelled flag but not finished. This behavior differs from documentation and makes fetch callback implementation less straightforward.

I couldn't find a fix yet. Maybe there's a better way to implement this test with the existing ones.

Side note: Thanks for the incredibly well thought, easy to use and yet very efficient sokol APIs.

Regards, Guillaume

[floooh]

Good catch! I actually need to debug a bit what happens in sfetch_dowork with such 'early-cancelled' request.

Normally this code should take care of the problem:

https://github.com/floooh/sokol/blob/d4ac122f36d7659a18b312fd4fa2317fb9e06a63/sokol_fetch.h#L2500-L2503

...but the response callback may already be called before that here (when no buffer is provided with the request):

https://github.com/floooh/sokol/blob/d4ac122f36d7659a18b312fd4fa2317fb9e06a63/sokol_fetch.h#L2475-L2477

I think such "early cancelled" requests should be dealt with already in the first loop (https://github.com/floooh/sokol/blob/d4ac122f36d7659a18b312fd4fa2317fb9e06a63/sokol_fetch.h#L2467-L2479), so that such requests are not even dispatched into the user_incoming ring buffer (instead call the response callback with finished+cancelled and free the item right away).

I'll try to look into it in the next few days.

[floooh]

I'm closing this PR in favour of https://github.com/floooh/sokol/pull/898 (besides fixing the issue I also replicated your test, and also added another test which checks behaviour when cancelling after the dispatch from outside the response callback).