Class: Async::Background::Runtime::Semaphore

Inherits:
Object
  • Object
show all
Defined in:
lib/async/background/runtime/semaphore.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(limit) ⇒ Semaphore

Returns a new instance of Semaphore.

Raises:

  • (ArgumentError) 


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# File 'lib/async/background/runtime/semaphore.rb', line 9

def initialize(limit)
  @limit = Integer(limit)
  raise ArgumentError, 'limit must be >= 1' unless @limit.positive?

  @available = @limit
  @waiting = WaitList.new
end

Instance Attribute Details

#limit ⇒ Object (readonly)

Returns the value of attribute limit.



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# File 'lib/async/background/runtime/semaphore.rb', line 7

def limit
  @limit
end

Instance Method Details

#acquire ⇒ Object 



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# File 'lib/async/background/runtime/semaphore.rb', line 20

def acquire
  wait
  return @available unless block_given?

  begin
    yield
  ensure
    release
  end
end

#available ⇒ Object 



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# File 'lib/async/background/runtime/semaphore.rb', line 17

def available = @available

#release ⇒ Object 



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# File 'lib/async/background/runtime/semaphore.rb', line 31

def release
  while (node = @waiting.shift)
    node.grant!
    return @available if node.resume
  end

  @available += 1
  @available
end

#waiting ⇒ Object 



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# File 'lib/async/background/runtime/semaphore.rb', line 18

def waiting = @waiting.size