libevent

This is a build2 package for the libevent C library. It 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 supports 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.

Currently, libevent supports /dev/poll, kqueue(2), event ports, POSIX select(2), Windows select(), poll(2), and epoll(4).

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.

Usage

To start using this library in your project, add the following depends value to your manifest, adjusting the version constraint as appropriate:

depends: libevent ^2.1.12

Then import the library in your buildfile:

import libs = libevent%lib{event_core}

If you need one or more of the optional libraries (discussed below), then you will need to use the dependency configuration mechanism to enable them. For example, if you wish to use both lib{event_core} and lib{event_extra} in your project, then you can add the following to your manifest:

depends:
\
libevent ^2.1.12
{
  require
  {
    config.libevent.extra = true
  }
}
\

And the following to your buildfile:

import libs = libevent%lib{event_core event_extra}

Importable targets

This package provides the following importable targets (see the upstream documentation for background):

lib{event_core}
lib{event_extra}
lib{event_openssl}
lib{event_pthreads}

All the libraries except lib{event_core} are optional, disabled by default, and can be enabled with the corresponding configuration variables (discussed below).

Configuration variables

This package provides the following configuration variables:

[bool] config.libevent.extra    ?= false
[bool] config.libevent.openssl  ?= false
[bool] config.libevent.pthreads ?= false

These variables can be used to enable the corresponding optional libraries (discussed above). Note that an attempt to enable the lib{event_pthreads} library on Windows has no effect.

Note also that the lib{event_core} library provides build2 metadata that describes the effective configuration:

lib{event_core}:
{
  libevent.extra    = $config.libevent.extra
  libevent.openssl  = $config.libevent.openssl
  libevent.pthreads = $config.libevent.pthreads
}