Lua c-api: How to identify the coroutine/thread involved in a lua_pushcclosure callback?

Question

Is there a way to know which thread (coroutine) executing a Lua script is at the origin of a lua_pushcclosure call?

In order to manage some stuff relative to lua threads (delayed pause/resume, or private thread variables) I need to identify the thread involved in the callback. I know I can get the thread index when creating it by using lua_gettop, but I can't find a way to use it so it helps identifying the thread when a lua_pushcclosure call is issued from a Lua script.

My current system permits nested script calls, so a script can execute other scripts (each nested script call create a new thread with the same lua_state. Thus the lua_state used to get multiple thread entries in the stack.)

I'm using Lua 5.2

"lua_pushcclosure callback" lua_pushcclosure is not a callback. Are you talking about when you call that function? — Nicol Bolas
Yes I am talking about when the function is called from within the lua script. The function exposed through lua_pushcclosure can be called from different threads and I need to identify which one. — Valkea

Nicol Bolas Nicol Bolas · Accepted Answer · 2012-09-08T15:00:07

If you're in a C function that has been called from Lua, and you want to know what thread you're in... just call lua_pushthread(L).

Lua c-api: How to identify the coroutine/thread involved in a lua_pushcclosure callback?

1 Answers