How to use lua_yield/lua_resume in C correctly?

[chuang <lichuang1982@...>]

I try to use  co-routines to simulate "pause" a script and wait until some processing is done before resuming,the C and Lua code is below, but it cannot work:

main.c:

#include <stdio.h>

#include "lua.h"

#include "lualib.h"

#include "lauxlib.h"

typedef int bool;

#define true 1

#define false 1

bool running = true;

int lua_finish(lua_State *L) {

  running = false;

  printf("lua_finish called\n");

  return 0;

}

int lua_sleep(lua_State *L) {

  printf("lua_sleep called\n");

  return lua_yield(L,0);

}

int main() {

  lua_State* L = lua_open();

  luaL_openlibs(L);

  lua_register(L, "sleep", lua_sleep);

  lua_register(L, "finish", lua_finish);

  lua_State* cL = lua_newthread(L);

  luaL_dofile(cL, "loop.lua");

  while (running) {

    int status;

    status = lua_resume(cL, 0);

    if (status == LUA_YIELD) {

      printf("loop yielding\n");

    } else {

      running=false; // you can't try to resume if it didn't yield

      if (status == LUA_ERRRUN && lua_isstring(cL, -1)) {

        printf("isstring: %s\n", lua_tostring(cL, -1));

        lua_pop(cL, -1);

        break;

      }

    }

  }

  lua_close(L);

  return 0;

}

loop.lua

print("loop.lua")

local i = 0

while true do

  print("lua_loop iteration")

  sleep()

  i = i + 1

  if i == 4 then

    break

  end

end

finish()

In Lua 5.1.4,when call lua_yield(),it thow "attempt to yield across metamethod/C-call boundary" error and return,so when call lua_resume in C it fails, how to fix it?