Linux::FD::Timer - Timer filehandles for Linux

Author

       Leon Timmermans <leont@cpan.org>

Copyright And License

       This software is copyright (c) 2010 by Leon Timmermans.

       This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
       programming language system itself.

perl v5.40.1                                       2025-04-19                              Linux::FD::Timer(3pm)

Description

       This module creates and operates on a timer that delivers timer expiration notifications via a file
       descriptor. It provides an alternative to the use of Time::HiRes' setitimer or POSIX::RT::Timer, with the
       advantage that the file descriptor may easily be monitored by mechanisms such as select, poll, and epoll.

Methods

new($clockid)
This creates a new timer object, and returns a file handle that refers to that timer. The clockid
argument specifies the clock that is used to mark the progress of the timer, and must be either
'realtime' or 'monotonic'. "realtime" is a settable system-wide clock. "monotonic" is a non-settable
clock that is not affected by discontinuous changes in the system clock (e.g., manual changes to system
time). The current value of each of these clocks can be retrieved using POSIX::RT::Clock. @flags is an
optional list of flags, currently limited to 'non-blocking' (requires Linux 2.6.27).

get_timeout()
Get the timeout value. In list context, it also returns the interval value. Note that this value is
always relative to the current time.

set_timeout(value,$interval=0,$abs_time=0)
Set the timer and interval values. If $abstime is true, they are absolute values, otherwise they are
relative to the current time. Returns the old value like "get_time" does.

receive
If the timer has already expired one or more times since its settings were last modified using settime(),
or since the last successful wait, then receive returns an unsigned 64-bit integer containing the number
of expirations that have occurred. If not it either returns undef or it blocks (if the handle is
blocking).

clocks
This returns a list of all known clocks usable in a timerfd. Do note that some clocks may require
superuser privileges.

Name

       Linux::FD::Timer - Timer filehandles for Linux

Synopsis

        use Linux::FD::Timer;

        my $fh = Linux::FD::Timer->new('monotonic', @flags);
        $fh->set_timeout(10, 10);
        while (1) {
            #do something..
            $fh->wait; #until the 10 seconds have passed.
        }