Class: Async::Condition

Inherits:
Object
  • Object
show all
Defined in:
lib/async/condition.rb

Overview

A synchronization primative, which allows fibers to wait until a particular condition is triggered. Signalling the condition directly resumes the waiting fibers and thus blocks the caller.

Direct Known Subclasses

Notification

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Condition

Returns a new instance of Condition.



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# File 'lib/async/condition.rb', line 28

def initialize
	@waiting = []
end

Instance Method Details

#empty? ⇒ Boolean

Is any fiber waiting on this notification?

Returns:

  • (Boolean) 


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# File 'lib/async/condition.rb', line 49

def empty?
	@waiting.empty?
end

#signal(value = nil) ⇒ void

This method returns an undefined value.

Signal to a given task that it should resume operations.

Parameters:

  • value (defaults to: nil) —

    The value to return to the waiting fibers.

See Also:



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# File 'lib/async/condition.rb', line 57

def signal(value = nil)
	waiting = @waiting
	@waiting = []
	
	waiting.each do |fiber|
		fiber.resume(value) if fiber.alive?
	end
	
	return nil
end

#wait ⇒ Object

Queue up the current fiber and wait on yielding the task.

Returns:

  • (Object) 


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# File 'lib/async/condition.rb', line 34

def wait
	fiber = Fiber.current
	@waiting << fiber
	
	Task.yield
	
	# It would be nice if there was a better construct for this. We only need to invoke #delete if the task was not resumed normally. This can only occur with `raise` and `throw`. But there is no easy way to detect this.
# ensure when not return or ensure when raise, throw
rescue Exception
	@waiting.delete(fiber)
	raise
end