Re: Time consuming function

[Eugen-Andrei Gavriloaie <shiretu@...>]

On Mar 31, 2008, at 2:27 PM, Alex Davies wrote:

> 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).
Well, still no joy... Same error:
`attempt to yield across metamethod/C-call boundary`

I sent previous mail thinking that I was making a mistake by returning  
1 instead of -1.
But unfortunately this is not the problem... I am missing something  
else.... :((((
I will try to experiment with the second solution: using luajit
> 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