Every

Calculate even intervals for Process.send_after/3. Sometimes we need to have periodic tasks to execute exactly at certain intervals, for example run task every 15 minutes within hour so we want to execute our task

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 automated.

Usage

Available methods

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

Every.minute/1 anf Every.hour/1 accepts optional parameter relative_to if provided then makes all calculation relative to given DateTime struct.

Every.minutes/2 anf Every.hour/2 both accept time interval as a first argument and optional parameter relative_to if provided then makes all calculation relative to given DateTime struct. First argument is literally to be read as Every N minutes/hours.

All methods return duration in seconds so it is your task to turn secons into milleseconds etc.

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 call will be at 12:05, 12:10 ... 12:55 ...
Process.send_after(self(), :work, Every.minutes(5) * 1000)

# If we want to trigger every minute
Process.send_after(self(), :work, Every.minute() * 1000)

# If we want to trigger every hour
Process.send_after(self(), :work, Every.hour() * 1000)

Installation

If available in Hex, the package can be installed by adding every to your list of dependencies in mix.exs:

def deps do
  [
    {:every, "~> 0.0.1"}
  ]
end

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/every.