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https://github.com/jonathanstowe/chronic
Scheduling thingy for Raku
https://github.com/jonathanstowe/chronic
cron raku schedule
Last synced: 2 months ago
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Scheduling thingy for Raku
- Host: GitHub
- URL: https://github.com/jonathanstowe/chronic
- Owner: jonathanstowe
- License: artistic-2.0
- Created: 2015-11-30T23:09:22.000Z (about 9 years ago)
- Default Branch: master
- Last Pushed: 2024-03-03T09:11:45.000Z (10 months ago)
- Last Synced: 2024-03-03T10:26:54.315Z (10 months ago)
- Topics: cron, raku, schedule
- Language: Raku
- Homepage:
- Size: 47.9 KB
- Stars: 7
- Watchers: 2
- Forks: 4
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Changelog: Changes
Awesome Lists containing this project
README
# Chronic
Scheduling thingy for Raku
## Synopsis
```raku
# Static configuration;
use Chronic;
react {
# Every minute
whenever Chronic.every() -> $v {
say "One: $v";
}
# Every five minutes
whenever Chronic.every(minute => '*/5') -> $v {
say "Five: $v";
}
# At 21:31 every day
whenever Chronic.every(minute => 31, hour => 21) -> $v {
say "21:31 $v";
}
}
# Dynamic configuration
use Chronic;
my @events = (
{
schedule => {},
code => sub ($v) { say "One: $v" },
},
{
schedule => { minute => '*/2' },
code => sub ($v) { say "Two: $v" },
},
{
schedule => { minute => '*/5' },
code => sub ($v) { say "Five: $v" },
},
{
schedule => { minute => 31, hour => 21 },
code => sub ($v) { say "21:31 $v"; },
},
);
for @events -> $event {
Chronic.every(|$event).tap($event);
}
# This has the effect of waiting forever
Chronic.supply.wait;
```
## Description
This module provides a low-level scheduling mechanism, that be used to
create cron-like schedules, the specifications can be provided as cron
expression strings, lists of integer values or [Junctions](https://docs.raku.org/type/Junction) of values.
There is a class method ```every``` that takes a schedule specification
and returns a ```Supply``` that will emit a value (a ```DateTime```) on
the schedule specified. There is also a method ```at``` (also a class
method) that returns a Promise that will be kept at a specified point
in time (as opposed to ```Promise.in``` which will return a Promise that
will be kept after a specified number of seconds.)
This can be used to build custom scheduling services like ```cron```
with additional code to read the specification from a file and arrange
the execution of the required thing or it could be used in a larger
program that may require to execute some code asynchronously periodically.
There is a single base Supply that emits an event at a 1 second frequency
in order to preserve the accuracy of the timings (in testing it may drift
by up to 59 seconds on a long run due to system latency if it didn't match
the seconds too,) so this may be a problem on a heavily loaded single core
computer. The sub-minute granularity isn't provided for in the interface
as it is easily achieved anyway with a basic supply, it isn't supported by
a standard ```cron``` and I think most code that would want to be executed
with that frequency would be more highly optimised then this may allow.
## Installation
If you have a working Rakudo you can install directly with *zef*:
# From the source directory
zef install .
# Remote installation
zef install Chronic
## Support
Suggestions/patches are welcomed via github at https://github.com/jonathanstowe/Chronic
## Licence
This is free software.
Please see the [LICENCE](LICENCE) file in the distribution.
© Jonathan Stowe 2015, 2016, 2017, 2019, 2020