Config Reader

A strongly typed, header only Lua-based config file reader for C++ 11. Supports runtime reloading of parameter values on config file save.

Example Usage

#include <csignal>
#include <iostream>

#include "config_reader/config_reader.h"

bool running = true;

void SigIntHandler(int signum) { running = false; }

int main() {
  signal(SIGINT, SigIntHandler);

  CONFIG_INT(test_int, "testInt");
  CONFIG_FLOAT(test_float, "tree.stree.number");
  CONFIG_STRING(test_string, "testString");
  config_reader::ConfigReader reader({"config.lua", "config2.lua"});
  while (running) {
    int local_int = CONFIG_test_int;
    std::cout << local_int << std::endl;
    if (local_int < 42) {
      std::cout << "It's less than 42!" << std::endl;
    }
    std::cout << CONFIG_test_float << std::endl;
    std::cout << CONFIG_test_string << std::endl;
  }
  return 0;
}

See examples/ for an interactive demo.

Dependencies

• Lua 5.1 Development Package
• C++ compiler with C++ 11 support (e.g. clang++)
• Eigen3

Ubuntu packages can be installed via InstallPackages.

Currently Supported C++ Types

• int
• unsigned int
• double
• float
• std::string
• bool
• Eigen::Vector2f
• Eigen::Vector3f
• vector<int>
• vector<unsigned int>
• vector<double>
• vector<float>
• vector<std::string>
• vector<bool>
• vector<Eigen::Vector2f>
• vector<Eigen::Vector3f>

Missing Variable Messages

By default this library only prints warning messages for missing requested variables if they are member variables of a top level variable. For example, consider the config file

foo = {
  bar = 0;
};

With the C++ bindings, attempting to load non existent top level variables, e.g. bar, or members of missing top level variables, e.g. bar.baz, will not print an error, but loading missing member variables such as foo.baz will print an error. This setting can be overridden by changing the compile time constant in lua_script.h.

Inotify Limits

The config reader library uses inotify file watches to automatically re-load configurations. It is common to have a low limit on the number of concurrent inotify watches. Under such circumstances, the config reader will fail to add watches with the following error:

ERROR: Couldn't add watch to the file: config.lua
Reason: No space left on device

The current limit can be viewed by running:

cat /proc/sys/fs/inotify/max_user_watches

The limit can be increased to its maximum by editing /etc/sysctl.conf and adding this line to the end of the file:

fs.inotify.max_user_watches=524288

The new value can then be loaded in by running sudo sysctl -p.
More details: https://github.com/guard/listen/wiki/Increasing-the-amount-of-inotify-watchers