waitutil provides tools for waiting for various conditions to occur, with a configurable delay time, timeout, and logging.

GitHub: https://github.com/rubytools/waitutil

RubyGems: http://rubygems.org/gems/waitutil

Documentation: http://rubytools.github.io/waitutil/

Wait methods take a block that returns true or false.

wait_for_condition waits for a condition computed by the given function. It takes two optional parameters, :timeout_sec and :delay_sec, that control how long the function waits before raising a timeout exception, and how frequently it checks for the condition. The time the condition block takes to evaluate is subtracted from the sleep time between successive checks. The timeout is one minute by default, and the delay time is one second.

WaitUtil.wait_for_condition("my_event to happen") do
  check_if_my_event_happened
end

WaitUtil.wait_for_condition("my_event to happen", :timeout_sec => 30, :delay_sec => 0.5) do
  check_if_my_event_happened
end

WaitUtil.wait_for_condition('my event', :verbose => true) { sleep(1) }

Output:

I, [2014-02-16T00:34:31.511915 #15897]  INFO -- : Waiting for my event for up to 60 seconds
I, [2014-02-16T00:34:32.512223 #15897]  INFO -- : Success waiting for my event (1.000153273 seconds)

attempt = 1
WaitUtil.wait_for_condition('my event', :verbose => true, :timeout_sec => 3, :delay_sec => 1) do
  sleep(1)
  attempt += 1
  [false, "attempt #{attempt}"]  # the second element goes into the log message
end

Output:

I, [2014-02-16T00:46:53.647936 #17252]  INFO -- : Waiting for my event for up to 3 seconds
WaitUtil::TimeoutError: Timed out waiting for my event (3 seconds elapsed): attempt 3
        from /home/mbautin/.rvm/gems/ruby-2.1.0/gems/waitutil-0.1.0/lib/waitutil.rb:39:in `wait_for_condition'
        from (irb):9
        from /home/mbautin/.rvm/rubies/ruby-2.1.0/bin/irb:11:in `<main>'

Wait for a TCP server to be available using wait_for_service:

WaitUtil.wait_for_service('my service', 'example.com', 80)

Apache License, Version 2.0