Run a python script or function only once in a given time frame.
If, for example, you have a script or service which might be called frequently, but you want to report errors only once daily to not annoy people too much, once_only is the library for you.
Suppose you want your script to complain, but not more than once a day.
once_only.daily is the tool you need:
import once_only
@once_only.daily
def complain():
print("This is not right!")
Now you can run complain as often as you want, from the same python
script or from others, it will only be run at
most once a day, so that at least 24 hours are between two complaints.
If you want to complain more or less often, there are other variants:
| object | time delta |
|---|---|
once_only.weekly |
1 week |
once_only.daily |
1 day |
once_only.hourly |
1 hour |
once_only.minutely |
1 minute |
once_only.Once() |
custom datetime.timedelta |
Instead of using a once_only.Once object as a decorator, you can also access
it directly via the check_ready() and
check_ready_trigger() functions:
import once_only
import datetime
once_every_two_hours = once_only.Once(datetime.timedelta(hours=2))
if once_every_two_hours.check_ready():
print("More than two hours have passed since last run!")
if not_a_dry_run and once_every_two_hours.check_ready_trigger():
print("Triggering timer and running!")
Note that all instances of once_only.Once with the same time delta share the
same timer, but those with different time deltas don't share the timer.
So, if you have never run anything before, this:
import once_only
import datetime
@once_only.minutely
def run_minutely():
print("minutely")
@once_only.hourly
def run_hourly():
print("hourly")
@once_only.Once(datetime.timedelta(minutes=60))
def run_every_60_minutes():
print("60 minutes")
run_minutely()
run_hourly()
run_every_60_minutes()
will print "minutely" and "hourly", but not "60 minutes" because
60 minutes is the same as one hour, so the 60 minutes timer will
already be triggered by run_hourly and run_every_60_minutes will not be
run.
Further documentation can be found at: https://once_only.readthedocs.io.
Copyright 2022, Potsdam-Institut für Klimafolgenforschung e.V.
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
https://www.apache.org/licenses/LICENSE-2.0
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