Luvit (Lua + libUV + jIT = pure awesomesauce)

Luvit is an attempt to do something crazy by taking node.js' awesome architecture and dependencies and seeing how it fits in the Lua language.

This project is still under heavy development, but it's showing promise. In initial benchmarking with a hello world server, this is between 2 and 4 times faster than node.js. Version 0.5.0 is the latest release version.

Do you have a question/want to learn more? Make sure to check out the mailing list and drop by our IRC channel, #luvit on Freenode.

-- Load the http library
local HTTP = require("http")

-- Create a simple nodeJS style hello-world server
HTTP.createServer(function (req, res)
  local body = "Hello World\n"
  res:writeHead(200, {
    ["Content-Type"] = "text/plain",
    ["Content-Length"] = #body
  })
  res:finish(body)
end):listen(8080)

-- Give a friendly message
print("Server listening at http://localhost:8080/")

Building from git

Grab a copy of the source code:

git clone https://github.com/luvit/luvit.git --recursive

To use the gyp build system run:

cd luvit
git submodule update --init --recursive
./configure
make -C out
tools/build.py test
./out/Debug/luvit

To use the Makefile build system (for embedded systems without python) run:

cd luvit
make
make test
./build/luvit

Debugging

Luvit contains an extremely useful debug API. Lua contains a stack which is used to manipulate the virtual machine and return values to 'C'. It is often very useful to display this stack to aid in debugging. In fact, this API is accessible via C or from Lua.

Stackwalk

require('_debug').stackwalk(errorString)

Displays a backtrace of the current Lua state. Useful when an error happens and you want to get a call stack.

example output:

Lua stack backtrace: error
    in Lua code at luvit/tests/test-crypto.lua:69 fn()
    in Lua code at luvit/lib/luvit/module.lua:67 myloadfile()
    in Lua code at luvit/lib/luvit/luvit.lua:285 (null)()
    in native code
    in Lua code at luvit/lib/luvit/luvit.lua:185 (null)()
    in native code
    in Lua code at [string "    local path = require('uv_native').execpat..."]:1 (null)()

Stackdump

require('_debug').stackdump(string)

luv_lua_debug_stackdump(L, "a message");

Stackdump is extremly useful from within C modules.

Debugger

require('_debug').debugger()

Supports the following commands:

• quit
• exit
• break
• clear
• clearall
• trace
• bt

The debugger will execute any arbitrary Lua statement by default.

Embedding

A static library is generated when compiling Luvit. This allows for easy embedding into other projects. LuaJIT, libuv, and all other dependencies are included.

#include <string.h>
#include <stdlib.h>
#include <limits.h> /* PATH_MAX */

#include "lua.h"
#include "lualib.h"
#include "lauxlib.h"

#ifndef WIN32
#include <pthread.h>
#endif
#include "uv.h"

#include "luvit.h"
#include "luvit_init.h"
#include "luv.h"

int main(int argc, char *argv[])
{
  lua_State *L;
  uv_loop_t *loop;

  argv = uv_setup_args(argc, argv);

  L = luaL_newstate();
  if (L == NULL) {
    fprintf(stderr, "luaL_newstate has failed\n");
    return 1;
  }

  luaL_openlibs(L);

  loop = uv_default_loop();

#ifdef LUV_EXPORTS
  luvit__suck_in_symbols();
#endif

#ifdef USE_OPENSSL
  luvit_init_ssl();
#endif

  if (luvit_init(L, loop, argc, argv)) {
    fprintf(stderr, "luvit_init has failed\n");
    return 1;
  }

  ... Run a luvit file from memory or disk ...
  ...    or call uv_run ...

  lua_close(L);
  return 0;
}