psched

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psched is a Ruby gem for precise time-scheduling of recurring tasks. Whenever a simple sleep() call is not precise enough, and not even a timing thread can satisfy your demands, psched is to the rescue!

The precise timing is obtained through the use of OS semaphores and a Ruby block as an anonymous callback that is regularly called by proper Signal::trap(:ALRM) usage. For this reason, psched only works on UNIX-like OSs (tested on MacOS and Linux).

In particular, scheduling of OS alarms is performed by ualarm(3) and alarm(3) LIBC calls, imported in PSched module through the Ruby FFI gem.

The FFI gem is also used for importing the setpriority(3) LICB function call, that can be used for elevating (under proper user access, sudo) the process priority for further improvements in timing precision (through PSched::Operation::prioritize() call.

require 'psched'

# Uncomment if needed:
# PSched::Operation.prioritize

op = PSched::Operation.new(0.5)
op.start(10) do |i|
  puts "Ping #{i}"
end

Signal.trap("SIGINT") do
  print "Stopping recurring process..."
  op.stop
  puts "done!"
end

sleep(0.2) while op.active?  # waits for scheduling to complete

FFI gem and an OS supporting semaphores.

$ gem install psched

The gem is built using the ore gem

Copyright (c) 2017 Paolo Bosetti

See LICENSE.txt for details.