Re: Time consuming function

["Alex Davies" <alex.mania@...>]

Hey,

I don't have a need for coroutines (or at least, haven't thought of one 
yet), but may be able to help. Firstly:

> int w_cfunc_call(lua_State *pLuaState)
> {
>     enqueue_request(...);
>     lua_yield(pLuaState,1);
>     return 1;
> }

should be:

> int w_cfunc_call(lua_State *pLuaState)
> {
>     enqueue_request(...);
>     return lua_yield(pLuaState,1);
> }

(lua_yield returns -1, to indicate to the vm that it's yielding).

Secondly, somewhere in your code you've got a C call waiting to return. Eg, 
if you try and yield from inside an __index metamethod, you'll get the error 
your seeing. Reason being that the (c) gettable function is still waiting 
for your metamethod to finish. The most common cause of that I believe is a 
lua_pcall, which does not allow yielding. One solution to this is to install 
luajit (recommended anyway), which brings with it coco which allows yielding 
and resuming from anywhere, even mid function. It does that by allocating c 
stacks as required, something that is impossible in ansi c but works well in 
practice.

- Alex