Call c function from Lua-lanes

Question

I want to call c function from lua using lanes.

int initApp(lua_State *L) {
    lua_createtable(L, 0, 0);
    
    lua_pushcfunction(L, get_appinfo);
    lua_setfield(L, -2, "get_appinfo");
    
    lua_setglobal(L, "App");
    
    return 0;
}

local function thread1(n)
    return App.get_appinfo(n)
end

function startlanes()
    local lanes = require 'lanes'
    package.preload['App'] = function() return App end
    package.loaded['App'] = App
    local app = require 'App'
    print(app, app.get_appinfo) --table: 0x1234    function: 0x5678
    --(1)
    f = lanes.gen('*', {required = {'App'}}, thread1) --Lua Error: module 'App' not found: no field package.preload['App']...
    --(2)
    --f = lanes.gen('App', thread1) -- Bad library name: App
    a = f(1)
    sleep(1)
end

When I run variant (1), I get Lua Error: module 'App' not found: no field package.preload['App']...no file '/App.lua'.... When I run variant (2), I get Bad library name: App.

How to call App.get_appinfo() using lanes? I can move all App functions into package, but it must be loaded from memory, not filesystem. I embed all lua packages.

Egor Skriptunoff · Answer 1 · 2021-11-29T16:39:22.973

0

Expose your C function initApp to Lua, for example, as _G.init_App

    lua_pushcfunction(L, initApp);
    lua_setglobal(L, "init_App");

Pass it as a parameter when starting each lane
Inside a lane, invoke init_App (received as the second parameter) - it will create your library

local function thread1(n, init_App)
    init_App()  -- create global table App in the current lane
    return App.get_appinfo(n)
end

function startlanes()
    local lanes = require 'lanes'
    local f = lanes.gen('*', thread1)
    a = f(1, init_App)  -- pass your module loader as argument
    sleep(1)
end

edited Nov 29 '21 at 16:39

answered Nov 26 '21 at 18:45

Egor Skriptunoff

23,359
2
34
64

How init_App will look? How to define/declare my c function here? – vvkatwss vvkatwss Nov 29 '21 at 16:04
Answer updated. – Egor Skriptunoff Nov 29 '21 at 16:39
Error: lanes.lua:329: main: function 'init_App' not found in Lane #0x100862008 destination transfer database. – vvkatwss vvkatwss Dec 01 '21 at 06:39
1

It seems I fixed it. I must add param `on_state_create=init_App` to `lanes.configure`. Lanes run this function in each state. Exactly what I looking for. No need to pass it to `thread1`. – vvkatwss vvkatwss Dec 01 '21 at 08:19
Egor, did you mean it? You can update your answer and I accept it as solved. And remove `init_App` from `thread1`. – vvkatwss vvkatwss Dec 01 '21 at 08:27
`did you mean it?` - No. My idea was to pass it as input parameter. So, this is your own idea, and you should write your own answer :-) – Egor Skriptunoff Dec 01 '21 at 13:23

score 0 · Accepted Answer · answered Dec 02 '21 at 07:28

To call c function, I must pass a function for on_state_create to lanes.configure.

//c code
int init_App(lua_State *L) {
    lua_createtable(L, 0, 0);
    
    lua_pushcfunction(L, get_appinfo);
    lua_setfield(L, -2, "get_appinfo");
    
    lua_setglobal(L, "App");
    
    return 0;
}

int init(lua_State *L) {
    lua_pushcfunction(L, init_App);
    lua_setglobal(L, "init_App");
    luaL_dostring(L, "local lanes = require 'lanes'.configure{on_state_create=init_App}; local l = lanes.linda()");
    luaL_dostring(L, "startlanes()");
}

--lua code
local function thread1(n)
    return App.get_appinfo(n)
end

function startlanes()
    local lanes = require 'lanes'
    local f = lanes.gen('*', thread1)
    a = f(1)
    sleep(1)
    print(a[1])
end

Call c function from Lua-lanes

2 Answers2