RE: running LUA code step by step

["Curt Carpenter" <curtc@...>]

> I want Lua to be able to rune multiple chunks/states/threads/whatever,
but be interruptible (to give control back to the controlling thread).

My solution, which requires 4.1:

In Windows, we have the concept of fibers--user scheduled execution
contexts within a thread, each with their own stack. In my thread, I
have a primary fiber, and a bunch of worker fibers. Fibers are extremely
lightweight to switch, compared to threads, and you don't have to worry
about making stuff thread safe. The main loop on the primary fiber looks
like this:

1) Fire up new fibers (and call lua_newthread) for new objects which
need their own script execution/stack/lua_state
2) Keep a list of objects that are ready to execute. Loop over all
objects and switch to their fiber.
3) In each object, figure out when they want to yield, either by a
line/call hook, or by a call into a registered C function that indicates
they need to wait (like a call that blocks on something out of its
control).
4) When an object is ready to yield, switch back to the primary fiber.
5) Depending on your needs, have some plan to add objects back to the
ready list. If you want all objects to execute code on every cycle, then
maybe you don't need a ready list, but I use it to mark scripts that are
ready to continue after having some condition met that they are blocked
on.

Curt