Class: CountingSemaphore

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

Overview

semaphore.rb Counting semaphore implementation for Ruby 1.9.3 Version: 0.0.1 Author: Luis Doubrava, Rob van Aarle Based on semaphore.rb,v 1.2 2003/03/15 20:10:10 fukumoto Exp

Instance Method Summary collapse

Constructor Details

#initialize(initvalue = 0) ⇒ CountingSemaphore

Returns a new instance of CountingSemaphore.


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# File 'lib/semaphore.rb', line 10

def initialize(initvalue = 0)
  @counter = initvalue
  @waiting_thread = nil
  @counter_mutex = Mutex.new
  @queue_mutex = Mutex.new
end

Instance Method Details

#exclusive ⇒ Object Also known as: synchronize 


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# File 'lib/semaphore.rb', line 52

def exclusive
  wait
  yield
ensure
  signal
end

#signal ⇒ Object Also known as: up, V 


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# File 'lib/semaphore.rb', line 31

def signal
  @counter_mutex.synchronize do
    begin
      if (@counter += 1) <= 0
        if @waiting_thread
          @waiting_thread.wakeup
          @waiting_thread = nil
        end
      end
    rescue ThreadError
      retry
    end
    self
  end
end

#wait ⇒ Object Also known as: down, P 


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# File 'lib/semaphore.rb', line 17

def wait
  @queue_mutex.synchronize do
    stop_thread = false
    @counter_mutex.synchronize do
      if (@counter -= 1) < 0
        @waiting_thread = Thread.current
        stop_thread = true
      end
      self
    end
    Thread.stop if stop_thread
  end
end