Ruby : force rand frequency

Question

I have to run a piece of code at randomly chosen times but I have to run it about once a day for instance. The program is not running all time so I can't really force it to run every hour and do something like if rand(1..24) == 1

How can I manage to have this kind of frequency without running it all time ?

When my computer is on, I can either use `crontab` or `sleep` and let the program run in background. But I don't know what solution's actually the best. — Cydonia7, Dec 21 '11 at 12:59
Do you need it to run every day, at least once? Can it run more than one per day? — Jay Elston, Dec 22 '11 at 14:30

Niklas B. · Accepted Answer · 2011-12-21T13:35:18.503

1

The program somehow needs to take the passed time since the last run into consideration, so that it gets more likely that it executes the longer it has not executed. Example using sleep:

def diff_in_hours(time1, time2)
  ((time1 - time2) / 3600) 
end

start = Time.now
loop do
  hours_since_last_run = diff_in_hours(Time.now, start).to_i
  # execution gets more and more likely the longer the last
  # run is in the past
  execute if [0, nil].include? rand(0..(24 - hours_since_last_run))
  sleep(60*60) # sleep one hour
end

edited Dec 21 '11 at 13:35

answered Dec 21 '11 at 13:30

Niklas B.

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Really nice idea, I'll try something like this ;) – Cydonia7 Dec 21 '11 at 16:17

Ruby : force rand frequency

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