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https://github.com/spider-gazelle/tasker
Scheduled tasks for crystal lang
https://github.com/spider-gazelle/tasker
Last synced: about 2 months ago
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Scheduled tasks for crystal lang
- Host: GitHub
- URL: https://github.com/spider-gazelle/tasker
- Owner: spider-gazelle
- License: mit
- Created: 2018-07-16T23:43:58.000Z (almost 6 years ago)
- Default Branch: master
- Last Pushed: 2024-03-10T01:57:14.000Z (4 months ago)
- Last Synced: 2024-03-10T02:47:09.909Z (4 months ago)
- Language: Crystal
- Size: 56.6 KB
- Stars: 53
- Watchers: 4
- Forks: 6
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Lists
- awesome-crystal - tasker - A high precision scheduler including timezone aware cron jobs (Scheduling)
- awesome-crystal - tasker - A high precision scheduler including timezone aware cron jobs (Scheduling)
README
# Tasker
[](https://github.com/spider-gazelle/tasker/actions/workflows/CI.yml)
A high precision scheduler for crystal lang.
Allows you to schedule tasks to run in the future and obtain the results.
Usage
=====
At a time in the future
```crystal
Tasker.at(20.seconds.from_now) { perform_action }
# If you would like the value of that result
# returns value or raises error - a Future
Tasker.at(20.seconds.from_now) { perform_action }.get
```
After some period of time
```crystal
Tasker.in(20.seconds) { perform_action }
```
Repeating every time period
```crystal
task = Tasker.every(2.milliseconds) { perform_action }
# Canceling stops the schedule from running
task.cancel
# Resume can be used to restart a canceled schedule
task.resume
```
You can grab the values of repeating schedules too
```crystal
tick = 0
task = Tasker.every(2.milliseconds) { tick += 1; tick }
# Calling get will pause until after the next schedule has run
task.get == 1 # => true
task.get == 2 # => true
task.get == 3 # => true
# It also works as an enumerable
# NOTE:: this will only stop counting once the schedule is canceled
task.each do |count|
puts "The count is #{count}"
task.cancel if count > 5
end
```
Running a CRON job
```crystal
# Run a job at 7:30am every day
Tasker.cron("30 7 * * *") { perform_action }
# For running in a job in a particular time zone:
berlin = Time::Location.load("Europe/Berlin")
Tasker.cron("30 7 * * *", berlin) { perform_action }
# Also supports pause, resume and enumeration
```
Timeout an operation
NOTE:: technically the operation isn't cancelled on timeout as there is no fiber cancel in crystal yet / no way to unwind stack consistently
```crystal
# Run some code that is expected to complete within a certain time period
result = Tasker.timeout(10.seconds) { perform_action }
```
## Pipelines
a non-blocking, asynchronous pipeline where each step only processes the input if it's not already processing the previous input.
```crystal
pipeline = Tasker::Pipeline(Input, Output).new("name") do |input|
process(input) # => Output
end
pipeline.chain { |output_of_first_step|
next_step(output_of_first_step)
}.subscribe { |output|
# a subscribe step is always run, even if it's already running
publish output
}
```
The idea is to maximise throughput with minimal latency.
Make sure to use the `-Dpreview_mt` flag when building.