Overhaul of thread handling to support blocking functions other than wait

luprex/eris-master/src/ldo.c

@@ -591,6 +591,9 @@ LUA_API int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k) {
   return 0;  /* return to 'luaD_hook' */
 }
 
+LUA_API int lua_isyieldable (lua_State *L) {
+  return (L->nny == 0);
+}
 
 int luaD_pcall (lua_State *L, Pfunc func, void *u,
                 ptrdiff_t old_top, ptrdiff_t ef) {

luprex/eris-master/src/lua.h

@@ -277,6 +277,7 @@ LUA_API int  (lua_yieldk) (lua_State *L, int nresults, int ctx,
 #define lua_yield(L,n)		lua_yieldk(L, (n), 0, NULL)
 LUA_API int  (lua_resume) (lua_State *L, lua_State *from, int narg);
 LUA_API int  (lua_status) (lua_State *L);
+LUA_API int  (lua_isyieldable) (lua_State *L);
 
 /*
 ** garbage-collection function and options