I've set up a system where Measurement
s are run based on MeasurementSetting
s. Each setting defines a schedule using ice_cube
(and some other properties for measurements). I'm able to edit this schedule for each setting and then poll for the next occurrences with something like:
def next_occurrences
schedule.occurrences(Time.now + 1.day)
end
This gives me a set of timestamps when there should be a Measurement
.
Now, I also have Sidekiq installed, and I can successfully run a measurement at a specific time using a MeasurementWorker
. To do that, I just create an empty Measurement
record, associate it with its settings, and then perform_async
(or perform_at(...)
) this worker:
class MeasurementWorker
include Sidekiq::Worker
sidekiq_options retry: 1, backtrace: true
def perform(measurement_id)
Measurement.find(measurement_id).run
end
end
What's missing is that I somehow need to create the empty measurements based on a setting's schedule. But how do I do this?
Say I have the following data:
MeasurementSetting
with ID 1, with a daily schedule at 12:00 PMMeasurementSetting
with ID 2, with an hourly schedule at every full hour (12:00 AM, 01:00 AM, etc.)Now I need to:
Measurement
that uses setting 1, every day at 12:00Measurement
that uses setting 2, every full hourBut how?
Should I check, say every minute, whether there is a MeasurementSetting
that is defined to occur now, and then create the empty Measurement
records, then run them with the specific setting using Sidekiq?
Or should I generate the empty Measurement
records with their settings in advance, and schedule them this way?
What would be the simplest way to achieve this?
Here's how I successfully did it:
Update your model that should run on a scheduled basis with a field planned_start_time
. This will hold the time when it was planned to start at.
Use the whenever
Gem to run a class method every minute, e.g. Measurement.run_all_scheduled
In that method, go through each setting (i.e. where the schedule is), and check if it is occurring now:
setting = MeasurementSetting.find(1) # get some setting, choose whatever
schedule = setting.schedule
if not schedule.occurring_at? Time.now
# skip this measurement, since it's not planned to run now
If that's the case, then check if we can run the measurement by looking in the database if there isn't any previous measurement with the same planned start time. So first, we have to get the planned start time for the current schedule, e.g. when it's now 3:04 PM. the planned start timeĀ could have been 3:00 PM.
this_planned_start_time = schedule.previous_occurrence(Time.now).start_time
Then we check if the last measurement's start time (limit(1)
gets just the last one) is the same or not.
if Measurement.limit(1).last.planned_start_time != this_planned_start_time
# skip this one, since it was already run
If not, we can continue setting up a measurement.
measurement = Measurement.create measurement_setting: setting,
planed_start_time: this_planned_start_time
Then run it:
measurement.delay.run