This document discusses event driven programming with AnyEvent. It provides an overview of AnyEvent and its support for various event loops. It also demonstrates how to use AnyEvent for non-blocking I/O, such as reading log files, by setting up a condition variable and watcher. Key AnyEvent methods are listed for setting up I/O, timers, signals, child processes and more.

1. Bulgarian Perl Workshop 2010
Event driven programing with
AnyEvent
Marian Marinov
mm@yuhu.biz

2. Event Driven programing
● select() ..... and wait
● fork() ..... and wait
● poll/epoll – define..... call when ready
● fork() + wait(WNOHANG)

3. AnyEvent supports
● EV ● Irssi
● Event ● Qt
● Glib ● Tk
● Event::Lib ● Own pure perl loops
● IO::Async
● POE

4. Log analyzer
Blocking example:
open FD, '-|', 'tail -f messages';
while(<FD>) { xxxxx; }
close FD;

5. Log analyzer
Non-blocking example:
my $result_ready = AnyEvent->condvar;
my $w = AnyEvent­>io (
fh => $fh,
poll => 'r',
cb => sub { $result_ready­>send; }
);
$result_ready­>recv;

6. AnyEvent methods
● AnyEvent­>io (fh => $fh, poll => "r", cb => sub { ... });
● AnyEvent­>timer (after => $seconds, cb => sub { ... });
● AnyEvent­>timer (after => $seconds, interval =>
$seconds, cb => ...
● AnyEvent­>now; # prints current event loop time
● AnyEvent­>time; # think Time::HiRes::time or simply
CORE::time.

7. AnyEvent methods
● AnyEvent­>signal (signal => "TERM", cb => sub { ... });
● AnyEvent­>child (pid => $pid, cb => sub { ... });
● AnyEvent­>idle (cb => sub { ... });
● AnyEvent­>condvar; # condition state
● $condition­>send; # send signal to the receivers
● $condition­>recv; # continue from here

8. How it's done
● Setup a condition
● Write what you want to do (setup a watcher)
– setup a producer into the watcher
● Set a stop point (consumer)