libuEv | Simple event loop for Linux

• Introduction
• API
  • Create an Event Context
  • Register an Event Watcher
  • Start Event Loop
  • Summary
• Using -luev
• Joystick Example
• Build & Install
• Origin & References

“Event driven software improves concurrency” -- Dave Zarzycki, Apple

Introduction

libuEv is a simple event loop in the style of the more established libevent, libev and the venerable Xt(3) event loop. The u (micro) in the name refers to both the small feature set and the small size overhead impact of the library.

Experienced developers may appreciate that libuEv is built on top of modern Linux APIs: epoll, timerfd and signalfd.

Example

The library documentation is available as a separate document.

#include <stdio.h>
#include <uev/uev.h>

static void cb(uev_t *w, void *arg, int events)
{
	printf("Callback runs every other second.\n");
}

int main(void)
{
	uev_t timer;
	uev_ctx_t *ctx;

	uev_init(&ctx);
	uev_timer_init(&ctx, &timer, cb, NULL, 2 * 1000, 0);

	return uev_run(&ctx, 0);
}

Build & Install

libuEv use the GNU configure and build system. To try out the bundled examples, use the --enable-examples switch to the configure script. There is also a limited unit test suite that can be useful to learn how the library works.

./configure
make -j5
make test
sudo make install-strip
sudo ldconfig

The resulting .so file is ~14 kiB.

Origin & References

libuEv was originally based on LibUEvent by Flemming Madsen but has been completely rewritten to provide a cleaner API. It is now more similar to the famous libev by Mark Lehmann. Another small event library used for inspiration is the very small picoev by Oku Kazuho.

libuEv is developed and maintained by Joachim Nilsson. It is built for and developed on GNU/Linux systems, patches to support *BSD and its kqueue interface are most welcome.