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Pure Ruby one-shot and periodic timers

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README.md

Timers

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Pure Ruby timer collections. Schedule several procs to fire after configurable delays or at periodic intervals.

This gem is especially useful when you are faced with an API that accepts a single timeout but you want to run multiple timers on top of it. An example of such a library is nio4r, a cross-platform Ruby library for using system calls like epoll and kqueue.

Usage

Create a new timer group with Timers.new:

require 'timers'

timers = Timers.new

Schedule a proc to run after 5 seconds with Timers#after:

five_second_timer = timers.after(5) { puts "Take five" }

The five_second_timer variable is now bound to a Timers::Timer object. To cancel a timer, use Timers::Timer#cancel

Once you've scheduled a timer, you can wait until the next timer fires with Timers#wait:

# Waits 5 seconds
timers.wait

# The script will now print "Take five"

You can schedule a block to run periodically with Timers#every:

every_five_seconds = timers.every(5) { puts "Another 5 seconds" }

loop { timers.wait }

If you'd like another method to do the waiting for you, e.g. Kernel.select, you can use Timers#wait_interval to obtain the amount of time to wait. When a timeout is encountered, you can fire all pending timers with Timers#fire:

loop do
  interval = timers.wait_interval
  ready_readers, ready_writers = select readers, writers, nil, interval

  if ready_readers || ready_writers
    # Handle IO
    ...
  else
    # Timeout!
    timers.fire
  end
end

You can also pause and continue individual timers, or all timers:

paused_timer = timers.every(5) { puts "I was paused" }

paused_timer.pause
10.times { timers.wait } # will not fire paused timer

paused_timer.continue
10.times { timers.wait } # will fire timer

timers.pause
10.times { timers.wait } # will not fire any timers

timers.continue
10.times { timers.wait } # will fire all timers

License

Copyright (c) 2014 Tony Arcieri. Distributed under the MIT License. See LICENSE for further details.

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