nim-schedules

A Nim scheduler library that lets you kick off jobs at regular intervals.

Features:

• Simple to use API for scheduling jobs.
• Support scheduling both async and sync procs.
• Lightweight and zero dependencies.

Getting Started

$ nimble install schedules

Usage

import schedules, times, asyncdispatch

schedules:
  every(seconds=10, id="tick"):
    echo("tick", now())

  every(seconds=10, id="atick", async=true):
    echo("tick", now())
    await sleepAsync(3000)

1. Schedule thread proc every 10 seconds.
2. Schedule async proc every 10 seconds.

Note:

• Don't forget adding --threads:on when compiling your application.
• The library schedules all jobs at a regular interval, but it'll be impacted by your system load.

Advance Usages

Throttling

By default, only one instance of the job is to be scheduled at the same time. If a job hasn't finished but the next run time has come, the next job will not be scheduled.

You can allow more instances by specifying throttle=. For example:

import schedules, times, asyncdispatch, os

schedules:
  every(seconds=1, id="tick", throttle=2):
    echo("tick", now())
    sleep(2000)

  every(seconds=1, id="async tick", async=true, throttle=2):
    echo("async tick", now())
    await sleepAsync(4000)

Customize Scheduler

Sometimes, you want to run the scheduler in parallel with other libraries. In this case, you can create your own scheduler by macro scheduler and start it later.

Below is an example of co-exist jester and nim-schedules in one process.

import times, asyncdispatch, schedules, jester

scheduler mySched:
  every(seconds=1, id="sync tick"):
    echo("sync tick, seconds=1 ", now())

router myRouter:
  get "/":
    resp "It's alive!"

proc main():
  # start schedules
  asyncCheck mySched.start()

  # start jester
  let port = paramStr(1).parseInt().Port
  let settings = newSettings(port=port)
  var jester = initJester(myrouter, settings=settings)

  # run
  jester.serve()

when isMainModule:
  main()

Set Start Time and End Time

You can limit the schedules running in a designated range of time by specifying startTime and endTime. For example,

import schedules, times, asyncdispatch, os

scheduler demoSetRange:
  every(
    seconds=1,
    id="tick",
    startTime=initDateTime(2019, 1, 1),
    endTime=now()+initDuration(seconds=10)
  ):
    echo("tick", now())

when isMainModule:
  waitFor demoSetRange.start()

ChangeLog

Released:

• v0.1.0, TBD.

TODO:

• Support macro cron().
• Support macro at().
• Support setting maxDue.

License

Nim-schedules is based on MIT license.