c - C 中的简单 lua_yield 无法从 Lua 正确恢复

Question

我刚刚开始使用 C 深入研究 lua 协程，我对我认为应该是我能想到的最简单的示例有疑问。

C:

#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>
#include <stdlib.h>

static int lua_test_yield(lua_State *L) {
        printf("1\n");
        lua_yield(L, 0);
        printf("2\n");
        lua_yield(L, 0);
        printf("3\n");
        lua_yield(L, 0);
        printf("4\n");
        lua_yield(L, 0);
        printf("5\n");
        lua_yield(L, 0);
        return 0;
}

static const struct luaL_Reg mylib[] = {
        {"test_yield", lua_test_yield},

        {NULL, NULL}
        };

// Used when the .so library is loaded from lua
int luaopen_mytest(lua_State *L) {
        luaL_newlib(L, mylib);
        return 1;
}

路亚

mytest = require 'mytest'

print("Loaded")
mytest_yeild = coroutine.create(function ()
        mytest.test_yield()
end)

for i=1,5 do
        print(coroutine.resume(mytest_yeild))
end 

结果:

$ lua test.lua 
Loaded
1
true
true
false   cannot resume dead coroutine
false   cannot resume dead coroutine
false   cannot resume dead coroutine

我觉得这很奇怪。为什么报两次成功的resume却什么都不打印，然后又报失败的resume？我在这里错过了什么？谢谢。

Answer 1

要在屈服后返回到 C 代码，您需要使用 lua_yieldk 并在单独的 C 函数中获取它，如下所示:

#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>
#include <stdlib.h>

static int lua_test_yield_6(lua_State *L, int status, lua_KContext ctx) {
        return 0;
}

static int lua_test_yield_5(lua_State *L, int status, lua_KContext ctx) {
        printf("5\n");
        return lua_yieldk(L, 0, 0, lua_test_yield_6);
}

static int lua_test_yield_4(lua_State *L, int status, lua_KContext ctx) {
        printf("4\n");
        return lua_yieldk(L, 0, 0, lua_test_yield_5);
}

static int lua_test_yield_3(lua_State *L, int status, lua_KContext ctx) {
        printf("3\n");
        return lua_yieldk(L, 0, 0, lua_test_yield_4);
}

static int lua_test_yield_2(lua_State *L, int status, lua_KContext ctx) {
        printf("2\n");
        return lua_yieldk(L, 0, 0, lua_test_yield_3);
}

static int lua_test_yield_1(lua_State *L) {
        printf("1\n");
        return lua_yieldk(L, 0, 0, lua_test_yield_2);
}

static const struct luaL_Reg mylib[] = {
        {"test_yield", lua_test_yield_1},

        {NULL, NULL}
        };

// Used when the .so library is loaded from lua
int luaopen_mytest(lua_State *L) {
        luaL_newlib(L, mylib);
        return 1;
}