NAME
Async::Event::Interval - Extremely simple timed asynchronous events
SYNOPSIS
A simple event. Multiple events can be simultaneously used. For an example using an event that can share data with the main application, examples of how to handle event crashes, and how to send parameters to your event callback, see "EXAMPLES".
use Async::Event::Interval;
my $event = Async::Event::Interval->new(
1.5,
\&callback
);
$event->start;
for (1..10){
print "$_: in main loop\n";
$event->stop if $_ == 3;
$event->start if $_ == 7;
if ($event->status){
print "event is running\n";
}
if ($event->status == -1){
print "event has crashed... restarting it\n";
$event->restart;
}
sleep 1;
}
sub callback {
print "timed event callback\n";
}DESCRIPTION
Very basic implementation of asynchronous events that are triggered by a timed interval. If no time is specified, we'll run the event only once.
Variables are not shared between the main application and the event. To do that, you'll need to use some form of memory sharing, such as IPC::Shareable. See "EXAMPLES" for an example. At this time, there is no real parameter passing or ability to return values. As I said... basic.
Each event is simply a separate forked process, which runs in a while loop.
METHODS
new($delay, $callback)
Returns a new Async::Event::Interval object. Does not create the event. Use start for that.
Parameters:
$delayMandatory: The interval on which to trigger your event callback, in seconds. Represent partial seconds as a floating point number. If zero is specified, we'll simply run the event once and stop.
$callbackMandatory: A reference to a subroutine that will be called every time the interval expires.
start
Starts the event timer. Each time the interval is reached, the event callback is executed.
stop
Stops the event from being executed.
restart
Alias for start(). Re-starts a stop()ped event.
status
Returns the event's process ID (true) if it is running, 0 (false) if it isn't, and -1 if the event has crashed.
waiting
Returns true if the event is dormant and is ready for a start() or restart command. Returns false if the event is already running.
EXAMPLES
Run Once
Send in an interval of zero (0) to have your event run a single time. Call start() repeatedly for numerous runs.
use Async::Event::Interval
my $event = Async::Event::Interval->new(0, sub {print "hey\n";});
$event->start;
# Do stuff, then run the event again if it's done its previous task
$event->start if $event->waiting;Event Parameters
You can send in a list of parameters to the event callback. Changing these within the main program will have no effect on the values sent into the event itself.
use Async::Event::Interval
my @params = qw(1 2 3);
my $event = Async::Event::Interval->new(
1,
\&callback,
@params
);
sub callback {
my ($one, $two, $three) = @_;
print "$one, $two, $three\n";
}Shared Data
A timed event where the event callback shares a hash reference with the main program.
use Async::Event::Interval;
use IPC::Shareable;
tie my $scalar, 'IPC::Shareable', undef;
$scalar = "hello";
my $event
= Async::Event::Interval->new(10, \&callback);
sub callback {
$scalar = "hello, world!";
}Event crash: Restart event
use warnings;
use strict;
use feature 'say';
use Async::Event::Interval;
my $event = Async::Event::Interval->new(
2,
sub {
kill 9, $$;
},
);
$event->start;
sleep 1; # do stuff
if ($event->status == -1){
say "event crashed, restarting";
$event->restart;
}Event crash: End program
use warnings;
use strict;
use feature 'say';
use Async::Event::Interval;
my $event = Async::Event::Interval->new(
2,
sub {
kill 9, $$;
},
);
$event->start;
sleep 1; # do stuff
if ($event->status == -1){
say "event crashed, can't continue...";
exit;
}AUTHOR
Steve Bertrand, <steveb at cpan.org>
LICENSE AND COPYRIGHT
Copyright 2021 Steve Bertrand.
This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.
See http://dev.perl.org/licenses/ for more information.