Class: Async::Waiter

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

Overview

A composable synchronization primitive, which allows one task to wait for a number of other tasks to complete. It can be used in conjunction with Semaphore and/or Barrier.

Instance Method Summary collapse

Constructor Details

#initialize(parent: nil, finished: Async::Condition.new) ⇒ Waiter 



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# File 'lib/async/waiter.rb', line 9

def initialize(parent: nil, finished: Async::Condition.new)
  @finished = finished
  @done = []
  
  @parent = parent
end

Instance Method Details

#async(parent: (@parent or Task.current), &block) ⇒ Object

Execute a child task and add it to the waiter.



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# File 'lib/async/waiter.rb', line 18

def async(parent: (@parent or Task.current), &block)
  parent.async do |task|
    yield(task)
  ensure
    @done << task
    @finished.signal
  end
end

#first(count = nil) ⇒ Object

Wait for the first ‘count` tasks to complete.



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# File 'lib/async/waiter.rb', line 31

def first(count = nil)
  minimum = count || 1
  
  while @done.size < minimum
    @finished.wait
  end
  
  return @done.shift(*count)
end

#wait(count = nil) ⇒ Object

Wait for the first ‘count` tasks to complete.



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# File 'lib/async/waiter.rb', line 43

def wait(count = nil)
  if count
    first(count).map(&:wait)
  else
    first.wait
  end
end