rufus-scheduler 2.0.12 released 2011-10-28 home comments

rufus-scheduler is a thread-based scheduler written in Ruby. It lets you write code like:

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require 'rufus-scheduler'

s = Rufus::Scheduler.start_new

s.every '10m' do
  puts 'open the window for the cat'
end

s.at '2012-01-01 12:00' do
  puts 'reminder: wife's birthday'
end

s.cron '0 22 * * 1-5' do
  puts 'activate the security system'
end

s.join # in case of stand-alone script...

The main addition brought by this release is the :mutex attribute when scheduling blocks of code. I was seeing people misusing :blocking => true to exclude block execution overlapping. It works but the scheduler is blocked as well, and crons might get skipped:

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s.every '10m', :blocking => true do
  puts 'doing this...'
  sleep 60 * 60 # 1 hour
  puts 'done.'
end

# if the scheduler is in the blocking task above, crons will get skipped...
s.at '2012-01-01 12:00' do
  puts 'do that.'
end

My advice was to use mutexes instead:

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$m = Mutex.new

s.every '10m' do
  $m.synchronize do
    puts 'doing this...'
    sleep 60 * 60 # 1 hour
    puts 'done.'
  end
end

# if the scheduler is in the blocking task above, crons will get skipped...
s.at '2012-01-01 12:00' do
  $m.synchronize do
    puts 'do that.'
  end
end

For those of you who use such mutexes and are OK with them wrapping the whole block, rufus-scheduler 2.0.12 introduces the :mutex attribute:

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s.every '10m', :mutex => 'my_mutex_name' do
  puts 'doing this...'
  sleep 60 * 60 # 1 hour
  puts 'done.'
end

# if the scheduler is in the blocking task above, crons will get skipped...
s.at '2012-01-01 12:00', :mutex => 'my_mutex_name'  do
  puts 'do that.'
end

Where rufus-scheduler receives a mutex name and manages it for you.

When one wants more control over the granularity, it’s OK to do:

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$m = Mutex.new

s.every '10m', :mutex => $m do
  puts 'doing this...'
  sleep 60 * 60 # 1 hour
  puts 'done.'
end

# if the scheduler is in the blocking task above, crons will get skipped...
s.at '2012-01-01 12:00' do
  puts 'do that'
  $m.synchronize do
    puts 'and that.'
  end
end

Remember that rufus-scheduler is not a cron replacement. Many thanks to all the people who complained or helped in the development of this piece of software over the years.

© 2011-2013 John Mettraux