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



45
46
47
48
49
50
51
 
# File 'lib/aws/flow/future.rb', line 45

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

#on_set(&block) ⇒ Object

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



63
64
65
66
67
 
# File 'lib/aws/flow/future.rb', line 63

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:



34
35
36
37
38
39
40
41
 
# 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) 


53
54
55
 
# File 'lib/aws/flow/future.rb', line 53

def set?
  @set
end

#unset ⇒ Object 



57
58
59
60
 
# File 'lib/aws/flow/future.rb', line 57

def unset
  @set = nil
  @result = nil
end