Help language development. Donate to The Perl Foundation

Scheduler::DelayBetween cpan:ATROXAPER last updated on 2021-01-22

NAME

Scheduler::DelayBetween - Standard Scheduler's cue sub with the possibility to set a delay between each code execution.

SYNOPSIS

use Scheduler::DelayBetween;

my $cancel = cue({ say 'boom'; sleep 3; }, :5in, :1delay-between);
sleep(5 + (3 + 1) * 13 + 0.7); # got 'boom' 14 times
$cancel.cancel;

DESCRIPTION

Sometimes you may need to execute some code several times with fixed delay between each execution. Standard Scheduler method cue does not provide such possibility. You can achieve it with this module.

It provides a single subroutine:

cue(&code, :$at, :$in, :$every, :$times = 0, :&stop, :&catch, :$delay-between, :$scheduler = $*SCHEDULER --> Cancellation)

Parameters meaning:

• &code - positional parameter - the code to run;
• :$at or :in - :$at can be an Instant before which the code won't be run. Alternatively,:$in is the number of seconds (possibly fractional) to wait before running the code. If :$at is in the past or :$in is negative, the delay is treated as zero. Implementations may equate to zero very small values (e.g., lower than 0.001s) of :$in or result of :$at - now;
• :$times - how many times the code has to be run. The parameter will be ignored if the value will be less than one. You can use this parameter together with :&stop, then the code will be run until at least one will stop it; :&stop - a check to decide should we continue to run the code. It will be called after each call of the code. Code running will stop if :&stop return True. You can use this parameter together with :$times, then the code will be run until at least one will stop it;
• :$scheduler - a scheduler to de used for scheduling the code running;
• :&catch - an exception handler, a sub with single positional parameter - exception occurred while the code running;
• :$delay-between - delay in seconds (possibly fractional), which must pass between each run of the code except before the first one. If the parameter is missed, then the cue call will be delegated to the cue method of :$scheduler. Implementations may equate to zero very small values (e.g., lower than 0.001s).
• :$every - will pass to the cue method of :$scheduler if you do not specify :$delay-between - you cannot use it together.

The subroutine will return a Cancellation object you can use to cancel the future code runs.

AUTHOR

Mikhail Khorkov [email protected]

Source can be located at: GitHub. Comments and Pull Requests are welcome.

COPYRIGHT AND LICENSE

Copyright 2021 Mikhail Khorkov

This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.