Module: BubbleWrap::Reactor::Deferrable

Included in:
DefaultDeferrable
Defined in:
motion/reactor/deferrable.rb

Overview

Provides a mixin for deferrable jobs.

Instance Method Summary collapse

Instance Method Details

#callback(&blk) ⇒ Object

Specify a block to be executed if and when the Deferrable object receives a status of :succeeded. See set_deferred_status for more information. Calling this method on a Deferrable object whose status is not yet known will cause the callback block to be stored on an internal list. If you call this method on a Deferrable whose status is :succeeded, the block will be executed immediately, receiving the parameters given to the prior set_deferred_status call.



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# File 'motion/reactor/deferrable.rb', line 18

def callback(&blk)
  return unless blk
  @deferred_status ||= :unknown
  if @deferred_status == :succeeded
    blk.call(*@deferred_args)
  elsif @deferred_status != :failed
    @callbacks ||= []
    @callbacks.unshift blk
  end
end

#cancel_timeoutObject

Cancels an outstanding timeout if any. Undoes the action of timeout.



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# File 'motion/reactor/deferrable.rb', line 30

def cancel_timeout
  @deferred_timeout ||= nil
  if @deferred_timeout
    @deferred_timeout.cancel
    @deferred_timeout = nil
  end
end

#errback(&blk) ⇒ Object

Specify a block to be executed if and when the Deferrable object receives a status of :failed. See set_deferred_status for more information.



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# File 'motion/reactor/deferrable.rb', line 41

def errback(&blk)
  return unless blk
  @deferred_status ||= :unknown
  if @deferred_status == :failed
    blk.call(*@deferred_args)
  elsif @deferred_status != :succeeded
    @errbacks ||= []
    @errbacks.unshift blk 
  end
end

#fail(*args) ⇒ Object Also known as: set_deferred_failure

Sugar for set_deferred_status(:failed, …)



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# File 'motion/reactor/deferrable.rb', line 53

def fail(*args)
  set_deferred_status :failed, *args
end

#set_deferred_status(status, *args) ⇒ Object

Sets the “disposition” (status) of the Deferrable object. See also the large set of sugarings for this method. Note that if you call this method without arguments, no arguments will be passed to the callback/errback. If the user has coded these with arguments, then the user code will throw an argument exception. Implementors of deferrable classes must document the arguments they will supply to user callbacks. OBSERVE SOMETHING VERY SPECIAL here: you may call this method even on the INSIDE of a callback. This is very useful when a previously-registered callback wants to change the parameters that will be passed to subsequently-registered ones. You may give either :succeeded or :failed as the status argument. If you pass :succeeded, then all of the blocks passed to the object using the callback method (if any) will be executed BEFORE the set_deferred_status method returns. All of the blocks passed to the object using errback will be discarded. If you pass :failed, then all of the blocks passed to the object using the errback method (if any) will be executed BEFORE the set_deferred_status method returns. All of the blocks passed to the object using # callback will be discarded. If you pass any arguments to set_deferred_status in addition to the status argument, they will be passed as arguments to any callbacks or errbacks that are executed. It’s your responsibility to ensure that the argument lists specified in your callbacks and errbacks match the arguments given in calls to set_deferred_status, otherwise Ruby will raise an ArgumentError.



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# File 'motion/reactor/deferrable.rb', line 84

def set_deferred_status(status, *args)
  cancel_timeout
  @errbacks ||= nil
  @callbacks ||= nil
  @deferred_status = status
  @deferred_args = args
  case @deferred_status
  when :succeeded
    if @callbacks
      while cb = @callbacks.pop
        cb.call(*@deferred_args)
      end
    end
    @errbacks.clear if @errbacks
  when :failed
    if @errbacks
      while eb = @errbacks.pop
        eb.call(*@deferred_args)
      end
    end
    @callbacks.clear if @callbacks
  end
end

#succeed(*args) ⇒ Object Also known as: set_deferred_success

Sugar for set_deferred_status(:succeeded, …)



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# File 'motion/reactor/deferrable.rb', line 109

def succeed(*args)
  set_deferred_status :succeeded, *args
end

#timeout(seconds) ⇒ Object

Setting a timeout on a Deferrable causes it to go into the failed state after the Timeout expires (passing no arguments to the object’s errbacks). Setting the status at any time prior to a call to the expiration of the timeout will cause the timer to be cancelled.



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# File 'motion/reactor/deferrable.rb', line 118

def timeout(seconds)
  cancel_timeout
  me = self
  @deferred_timeout = Timer.new(seconds) {me.fail}
end