Network Programming
with AnyEvent
PtPW’08 - {mailto,xmpp}:melo@simplicidade.org

Contenders
• POE
• Event
• Danga::Socket
• AnyEvent

Overhead
10k servers, 20k sockets, 1% active
15,000
11,250
7,500
3,750
0
create request
EV Perl Event Glib POE

Overhead
10k servers, 20k sockets
300
225
150
75
0
create request
EV Perl Event

Overhead
8 servers, 16 sockets
300
225
150
75
0
create request
EV Perl Event Glib POE

Overhead
8 servers, 16 sockets
90.0
67.5
45.0
22.5
0
create request
EV Perl Event Glib

AnyEvent
• framework for event driven programming
• thin layer above several event loops
• EV, Event, Gtk, Tk, POE
• deals with IO handles (incl. unix domain
sockets), timers, signals, processes
• thousands of sockets with proper event
loop (EV)

Watchers and
Condvars
• AnyEvent has two basic concepts
• Watchers
• Condvars
• Watchers wait for externals events: socket
input, timer expiration, child process exits
• Condvars are a synchronization primitive

IO Watchers
• Covers file handles, sockets, unix domain
sockets
• Deals with buffered reads and writes
• Can also deal with “reading lines” or “block
of bytes”: callback only when we have
everything

Timers
• Execute callback sometime in the future
• Single shot timers only
• Common uses: timeouts

Condvars
• Provide syncronization inside your program
• A simple broadcast service
• Multiple interested parties
• Anybody can trigger it
• All the interested parties will be notified

Read a line
$| = 1; print \"enter your name> \";
my $name = <STDIN>;

Read a line, take II
use AnyEvent;
$| = 1; print \"enter your name> \";
my $name;
my $wait_for_input = AnyEvent->io (
fh => \\*STDIN,
poll => \"r\",
cb => sub {
$name = <STDIN>;
}
);

Demo
• A simple broadcast server
• Multiple clients
• Broadcasts lines sent by one client to all
the others
• Code http://github.com/melo/presentations/

Thanks!