Re: [Wxlua-users] Multiple Lua instances in multi-threading app

[John L. <jla...@gm...>]

On 8/9/06, he...@gm... <he...@gm...> wrote:
> Hello,
> I'd like to use wxLua in a multi-threading application, several threads should host their own Lua instance.
> The Lua instances should run independent from the others, not sharing anything.
> So I create a wxLuaState object for every thread and use RunFile to execute the script.

No problems, except that any GUI functions MUST be made from the main
thread. This is a limitation of wxWidgets due to the underlying gui
system which is true for pure C++ code as well..

> But: I also want to use own functions (published through RegisterFunction) and I can't manage to get them independent.
> I would have to declare them in a global scope (or as static member functions), both would lead to a common function
> implementation which is called from all threads. But I want to have them separate, to avoid any interference between the Lua threads.
>
> Can anybody give me a hint how to do this?

I think you're wondering how to have the underlying C function
independent for each thread since each
wxLuaState::RegisterFunction(...) call for a given lua state pushes
the function independently into the lua_State already.

Simple case: Just have multiple C functions if you'll only have a
small known number of them.

More complicated: I am not very well versed in C threading, but I
believe that you will have to have mutexes (and/or conditions?)  for
each wxLuaState you create (maybe a wxList mapping between the
lua_State of the wxLuaState and it's mutexes, keyed on the memory
location of the lua_State?), then look up from within the C function
which lua_State is "active" and do the mutex thing in there. In other
words lua doesn't know about the threading and the C functions handle
it all internally.

I hope this makes some sort of sense,
    John Labenski