NAME¶
"IO::Async::Timer::Periodic" - event callback at regular intervals
SYNOPSIS¶
use IO::Async::Timer::Periodic;
use IO::Async::Loop;
my $loop = IO::Async::Loop->new;
my $timer = IO::Async::Timer::Periodic->new(
interval => 60,
on_tick => sub {
print "You've had a minute\n";
},
);
$timer->start;
$loop->add( $timer );
$loop->run;
DESCRIPTION¶
This subclass of IO::Async::Timer implements repeating events at regular clock
intervals. The timing may or may not be subject to how long it takes the
callback to execute. Iterations may be rescheduled runs at fixed regular
intervals beginning at the time the timer was started, or by a fixed delay
after the previous code has finished executing.
For a "Timer" object that only runs a callback once, after a given
delay, see instead IO::Async::Timer::Countdown. A Countdown timer can also be
used to create repeating events that fire at a fixed delay after the previous
event has finished processing. See als the examples in
"IO::Async::Timer::Countdown".
EVENTS¶
The following events are invoked, either using subclass methods or CODE
references in parameters:
on_tick¶
Invoked on each interval of the timer.
PARAMETERS¶
The following named parameters may be passed to "new" or
"configure":
- on_tick => CODE
- CODE reference for the "on_tick" event.
- interval => NUM
- The interval in seconds between invocations of the callback
or method. Cannot be changed if the timer is running.
- first_interval => NUM
- Optional. If defined, the interval in seconds after calling
the "start" method before the first invocation of the callback
or method. Thereafter, the regular "interval" will be used. If
not supplied, the first interval will be the same as the others.
Even if this value is zero, the first invocation will be made
asynchronously, by the containing "Loop" object, and not
synchronously by the "start" method itself.
- reschedule => STRING
- Optional. Must be one of "hard", "skip"
or "drift". Defines the algorithm used to reschedule the next
invocation.
"hard" schedules each iteration at the fixed interval from the
previous iteration's schedule time, ensuring a regular repeating event.
"skip" schedules similarly to "hard", but skips over
times that have already passed. This matters if the duration is
particularly short and there's a possibility that times may be missed, or
if the entire process is stopped and resumed by "SIGSTOP" or
similar.
"drift" schedules each iteration at the fixed interval from the
time that the previous iteration's event handler returns. This allows it
to slowly drift over time and become desynchronised with other events of
the same interval or multiples/fractions of it.
Once constructed, the timer object will need to be added to the "Loop"
before it will work. It will also need to be started by the "start"
method.
AUTHOR¶
Paul Evans <leonerd@leonerd.org.uk>