Calculate even intervals for scheduling with Process.send_after/3
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Calculate even intervals for Process.send_after/3. Sometimes we need to have periodic tasks to be executed exactly at certain intervals, for example running a task every 15 minutes.

  1. At the beginning of hour,
  2. 15th minute,
  3. 30th minute,
  4. 45th minute.

So instead of doing it manually, it is better if it is automated.


Available functions:

  • Every.minute/1
  • Every.minutes/2
  • Every.hour/1
  • Every.hours/2

All functions accept an optional relative_to (DateTime or NaiveDateTime) parameter which can be used to fake the current moment in time. If it is not provided, the current time will be used.

Every.minute/1, Every.hour/1 and only accept the optional relative_to parameter. They return the milliseconds left until the next minute/hour/day.

Every.minutes/2 and Every.hours/2 both accept an interval as first parameter and the optional relative_to as second parameter. They return the milliseconds until the the next interval.

Note: All functions return the difference in milliseconds!

How to use with periodic tasks

# Lets say we want to trigger our task every 5 minutes and current time is 12:02
# so next calls will be at 12:05, 12:10 ... 12:55 ...
Process.send_after(self(), :work, Every.minutes(5))

# If we want to trigger every minute
Process.send_after(self(), :work, Every.minute())

# If we want to trigger every hour
Process.send_after(self(), :work, Every.hour())

# If we want to trigger every 2 hours
Process.send_after(self(), :work, Every.hours(2))

# If we want to trigger every day
Process.send_after(self(), :work,


This library can be installed by adding every to the list of dependencies in your mix.exs:

def deps do
  [{:every, "~> 0.0.6"}]

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