libevent – an event notification library
The libevent
API provides a mechanism to execute a callback function when a specific event occurs on a file descriptor or after a timeout has been reached. Furthermore, libevent
also support callbacks due to signals or regular timeouts.
libevent
is meant to replace the event loop found in event driven network servers. An application just needs to call event_dispatch() and then add or remove events dynamically without having to change the event loop.
NOTE:
For event driven network servers, please refer to this article .
Currently, libevent
supports /dev/poll
, kqueue(2)
, event ports
, POSIX select(2), Windows select(), poll(2), and epoll(4)
. The internal event mechanism is completely independent of the exposed event API, and a simple update of libevent can provide new functionality without having to redesign the applications. As a result, libevent
allows for portable application development and provides the most scalable event notification mechanism available on an operating system.
NOTE:
obviously,the implementation of
libevent
is very good,which conforms to the idea of interface-oriented programming.
Libevent
can also be used for multi-threaded applications, either by isolating each event_base
so that only a single thread accesses it, or by locked access to a single shared event_base
. libevent
should compile on Linux, *BSD
, Mac OS X, Solaris, Windows, and more.
Libevent
additionally provides a sophisticated framework for buffered network IO, with support for sockets, filters, rate-limiting, SSL
, zero-copy file transmission, and IOCP
. Libevent
includes support for several useful protocols, including DNS
, HTTP, and a minimal RPC framework.
More information about event notification mechanisms for network servers can be found on Dan Kegel's "The C10K problem" web page.