mod_cron
Provides periodic events and scheduling of regular module specific jobs.
Current this module sends tick notifications at periodic intervals. These ticks can be observed to implement periodic tasks.
Other modules can schedule jobs which should be triggered at specific intervals
tick
For periodic tasks the system has various periodic tick events. They are named after their interval s for seconds, m for minutes, and h for hours.
- tick_1s
- tick_1m
- tick_10m
- tick_15m
- tick_30m
- tick_1h
- tick_2h
- tick_3h
- tick_4h
- tick_6h
- tick_12h
- tick_24h
Example
Check something every hour.
-include_lib("kernel/include/logger.hrl").
observe_tick_1h(tick_1h, Context) ->
?LOG_INFO("And another hour has passed..."),
do_something(Context).
The return value is ignored.
The tick observers are called one by one in a separate process. So a slow handler can delay the other handlers.
Schedule Module Specific Jobs
When you want to schedule regular jobs, when you want your module to perorm jobs at regular intervals it is possible to use mod_cron to schedule those jobs.
For example, if you want to send out an automated weekly reminder to your users you can do this by defining a module specific task in your module.
Example:
-mod_depends([cron]).
-mod_cron_jobs([
{{weekly, mon, {10, 0, 0}}, {?MODULE, send_weekly_reminders, []}}
]).
This definition will be read and will cause the function send_weekly_reminders to be called at monday’s on 10:00 UTC. The function will be called with a context of the site.
Example:
send_weekly_reminders(Context) ->
Events = get_this_weeks_events(Context),
send_email_reminders(Events, Context).
This function will then send out reminders of events taking place the coming week. Its definition will cause it to be called on monday moring 10:00 UTC. Note that the Context parameter will automatically be added to the function call.
The scheduling of events is done by erlcron. For online documentation on how to schedule jobs and their syntax definition, see: https://hexdocs.pm/erlcron/readme.html