[Date Prev][Date Next][Thread Prev][Thread Next]
[Date Index]
[Thread Index]
- Subject: Re: Forcing coroutine.resume to call the yielding function again
- From: Tim Hill <drtimhill@...>
- Date: Mon, 19 Aug 2019 23:58:48 -0700
> On Aug 19, 2019, at 7:07 AM, Andreas Falkenhahn <andreas@falkenhahn.com> wrote:
>
> I think it is possible, you just need the right trick ;) I've now come up with something that seems to do the job: The key to success was realizing that it is perfectly legal for Lua hooks to yield. Since Lua hooks can be called before every instruction I can just use this insight to yield before OP_CALL instead of during it.
>
No, Philippe is quite correct, there is no “trick” you can pull to work around this. To implement coroutines, Lua uses “long jumps” in C, and these implicitly demolish the C call stack. This means that lua_yield() NEVER RETURNS and any function that calls lua_yield() is abandoned (and any nested outer C functions as well). Whatever you do can not work around the fact that to yield a coroutine MUST demolish the C stack but the very way in which Lua intermixes the Lua and C stacks.
—Tim
