Class: AWS::Flow::Core::Future

Inherits:
Object
  • Object
show all
Defined in:
lib/aws/flow/future.rb

Overview

A Future represents the result of an asynchronous computation. Methods are provided to check if the computation is complete(Future#set), to wait for its completion(Future#wait), and to retrieve the result of the computation(Future#get). The result can only be retrieved using method get when the computation has completed, blocking if necessary until it is ready. This is okay, however, because it will block that Fiber, and another Fiber will start executing

Instance Method Summary collapse

Instance Method Details

#get ⇒ Object

Blocks if Future is not set raises CancellationError when task is cancelled



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# File 'lib/aws/flow/future.rb', line 51

def get
  until @set
    @conditional ||= FiberConditionVariable.new
    @conditional.wait
  end
  @result
end

#is_flow_future? ⇒ Boolean

determines whether the object is a flow future. The contract is that flow futures must have a #get method.

Returns:

  • (Boolean) 


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# File 'lib/aws/flow/future.rb', line 45

def is_flow_future?
  true
end

#on_set(&block) ⇒ Object

Add a callback, block, which will fire when the future is set



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# File 'lib/aws/flow/future.rb', line 69

def on_set(&block)
  @listeners ||= []
  # TODO probably want to use lambda here
  @listeners << block
end

#set(result = nil) ⇒ Object

Sets the value of the future, and notifies all of the Fibers that tried to get when this future wasn’t ready.

Raises:



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# File 'lib/aws/flow/future.rb', line 34

def set(result=nil)
  raise AlreadySetException if @set
  @set = true
  @result = result
  @conditional.broadcast if @conditional
  @listeners.each { |b| b.call(self) } if @listeners
  self
end

#set? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/aws/flow/future.rb', line 59

def set?
  @set
end

#unset ⇒ Object 



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# File 'lib/aws/flow/future.rb', line 63

def unset
  @set = nil
  @result = nil
end