Lua 协程

Question

我正在尝试了解如何使用协同程序来“暂停”脚本并等到某些处理完成后再恢复。

也许我以错误的方式看待协同例程。但我的尝试的结构类似于answer 中给出的示例。

loop.lua 中的循环永远不会达到第二次迭代，因此永远不会达到退出 C 代码中正在运行的循环所需的 i == 4 条件。如果我没有在loop.lua 中让步，那么此代码将按预期执行。

ma​​in.cpp

#include <lua/lua.hpp>

bool running = true;

int lua_finish(lua_State *) {
    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);

    luaL_dofile(L, "scripts/init.lua");

    lua_State* cL = lua_newthread(L);
    luaL_dofile(cL, "scripts/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
            // catch any errors below
            if (status == LUA_ERRRUN && lua_isstring(cL, -1)) {
                printf("isstring: %s\n", lua_tostring(cL, -1));
                lua_pop(cL, -1);
            }
        }
    }

    luaL_dofile(L, "scripts/end.lua");
    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()

编辑：添加了赏金，希望能在如何完成此任务方面获得一些帮助。

Answer 1

lua_resume 的返回代码 2 是 LUA_ERRRUN。检查 Lua 堆栈顶部的字符串以找到错误消息。

类似的模式对我有用，尽管我确实使用了coroutine.yield 而不是lua_yield，而且我使用的是 C 而不是 C++。我不明白为什么您的解决方案不起作用

在您的简历电话中，不清楚您是否过度简化了示例，但我会在您的 while 循环中进行以下更改：

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
  // catch any errors below
  if (status == LUA_ERRRUN && lua_isstring(cL, -1)) {
    printf("isstring: %s\n", lua_tostring(cL, -1));
    lua_pop(cL, -1);
  }
}

编辑 2：

对于调试，请在运行简历之前添加以下内容。你有一个字符串被推到堆栈的某个地方：

int status;
// add this debugging code
if (lua_isstring(cL, -1)) {
  printf("string on stack: %s\n", lua_tostring(cL, -1));
  exit(1);
}
status = lua_resume(cL,0);

编辑 3：

哦，天哪，我不敢相信我还没有看到这一点，当你要让步时，你不想运行luaL_dofile，因为据我所知，你不能直接生成 pcall ，这就是dofile中发生的事情（5.2会通过，但我认为你仍然需要lua_resume）。切换到这个：

luaL_loadfile(cL, "scripts/loop.lua");

Answer 2

上次我弄乱了 Lua 协程我以这样的代码结束

const char *program =
"function hello()\n"
"  io.write(\"Hello world 1!\")\n"
"  io.write(\"Hello world 2!\")\n"
"  io.write(\"Hello world 3!\")\n"
"end\n"
"function hate()\n"
"  io.write(\"Hate world 1!\")\n"
"  io.write(\"Hate world 2!\")\n"
"  io.write(\"Hate world 3!\")\n"
"end\n";

const char raw_program[] = 
"function hello()\n"
"  io.write(\"Hello World!\")\n"
"end\n"
"\n"
"cos = {}\n"
"\n"
"for i = 0, 1000, 1 do\n"
"  cos[i] = coroutine.create(hello)\n"
"end\n"
"\n"
"for i = 0, 1000, 1 do\n"
"  coroutine.resume(cos[i])\n"
"end";

int _tmain(int argc, _TCHAR* argv[])
{
    lua_State *L = lua_open();
    lua_State *Lt[1000];
    global_State *g = G(L);

    printf("Lua memory usage after open: %d\n", g->totalbytes);

    luaL_openlibs(L);

    printf("Lua memory usage after openlibs: %d\n", g->totalbytes);

    lua_checkstack(L, 2048);

    printf("Lua memory usage after checkstack: %d\n", g->totalbytes);

    //lua_load(L, my_lua_Reader, (void *)program, "code");
    luaL_loadbuffer(L, program, strlen(program), "line");

    printf("Lua memory usage after loadbuffer: %d\n", g->totalbytes);

    int error = lua_pcall(L, 0, 0, 0);
    if (error) {
        fprintf(stderr, "%s", lua_tostring(L, -1));
        lua_pop(L, 1);
    }

    printf("Lua memory usage after pcall: %d\n", g->totalbytes);

    for (int i = 0; i < 1000; i++) {
        Lt[i] = lua_newthread(L);
        lua_getglobal(Lt[i], i % 2 ? "hello" : "hate");
    }

    printf("Lua memory usage after creating 1000 threads: %d\n", g->totalbytes);

    for (int i = 0; i < 1000; i++) {
        lua_resume(Lt[i], 0);
    }

    printf("Lua memory usage after running 1000 threads: %d\n", g->totalbytes);

    lua_close(L);

    return 0;
}

您似乎无法将文件加载为协程？而是改用函数，而且应该选择到栈顶。

lua_getglobal(Lt[i], i % 2 ? "hello" : "hate");