Method: Wait#until

Defined in:
lib/wait.rb

#until(&block) ⇒ Object

Description

Wait#until executes a block until there’s a valid (by default, truthy) result. Useful for blocking script execution until:

  • an HTTP request was successful

  • a port has opened

  • a process has started

  • etc.

Examples

wait = Wait.new
# => #<Wait>
wait.until { Time.now.sec.even? }
# [Counter] attempt 1/5
# [Tester]  result: false
# [Rescuer] rescued: Wait::ResultInvalid
# [Raiser]  not raising: Wait::ResultInvalid
# [Delayer] delaying for 1s
# [Counter] attempt 2/5
# [Tester]  result: true
# => true

If you wish to handle an exception by attempting the block again, pass one or an array of exceptions with the :rescue option.

wait = Wait.new(:rescue => RuntimeError)
# => #<Wait>
wait.until do |attempt|
  case attempt
  when 1 then nil
  when 2 then raise RuntimeError
  when 3 then "foo"
  end
end
# [Counter] attempt 1/5
# [Tester]  result: nil
# [Rescuer] rescued: Wait::ResultInvalid
# [Raiser]  not raising: Wait::ResultInvalid
# [Delayer] delaying for 1s
# [Counter] attempt 2/5
# [Rescuer] rescued: RuntimeError
# [Raiser]  not raising: RuntimeError
# [Delayer] delaying for 1s
# [Counter] attempt 3/5
# [Tester]  result: "foo"
# => "foo"

Returns

The result of the block if valid (by default, truthy).

Raises

If no results are valid, the exception from the last attempt made.



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# File 'lib/wait.rb', line 124

def until(&block)
  # Reset the attempt counter.
  @counter.reset
  begin
    # Increment the attempt counter.
    @counter.increment
    # Wrap the given block in a timeout.
    result = Timeout.timeout(@timeout, TimeoutError) do
      # Execute the block and pass the attempt count (an +Integer+) to it.
      yield(@counter.attempt)
    end
    # Raise an exception unless the result is valid.
    @tester.valid?(result) ? result : raise(ResultInvalid)
  rescue TimeoutError, ResultInvalid, *@rescuer.exceptions => exception
    # Log the exception.
    @rescuer.log(exception)
    # Raise the exception if it ought to be.
    raise(exception) if @raiser.raise?(exception)
    # Raise the exception if this was the last attempt.
    raise(exception) if @counter.last_attempt?
    # Sleep before the next attempt.
    @delayer.sleep
    # Try the block again.
    retry
  end
end