Co routine local data / best practices

[Chris Gagnon <cgagnon@...>]

Since ref and the corresponding rawgeti are the fast methods for table access i use the following code to create myself a new co routine.

lua_getfield(MainState, LUA_GLOBALSINDEX, "ThreadTable");

lua_State *thread = lua_newthread(MainState);
int refID = luaL_ref(MainState, -2);
lua_pop(MainState,1);

So now the when i want to let GC clean up the coroutine i need to :

lua_getfield(MainState, LUA_GLOBALSINDEX, "ThreadTable");
luaL_unref(MainState, -1, refID );

The remaining piece is where do i get refID when i want to unref? or how do I store that refID with the co routine?
Here are some of the possibilities/issues i have run into.

• Environment table
  I have multiple co routines sharing an environment which dosn't allow me to uniquely store this value,
  without another table which is undesirable from a complexity/performance standpoint
  
• Stack
  Since the new stack is the only thing completely unshared when creating a co routine, I simply push the value onto the stack.
  This works like a charm until an error case, errors leave the stack in the layout of the function that ran into the problem.
  In this case i do not know how to recover the refID to properly clean up.

Thoughts about my specific issues?
Other suggestions/approaches that i haven't mentioned?

 Performance is a big concern to me with that in mind I'm curious how you guys would solve/layout something like this.

-Chris