Class: Barrier

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

Overview

A synchronization barrier enables multiple threads to wait until all threads have all reached a particular point of execution before any thread continues.

Instance Method Summary collapse

Constructor Details

#initialize(count) ⇒ Barrier

Initialize new barrier. The count argument specifies the number of threads that must call #wait before any of them successfully return from the call. The value specified by count must be greater than zero.

For example

b = Barrier.new(3)
3.times do
  Thread.new do
    print 1
    b.wait
    print 2
  end
end
sleep(1)
puts

produce

111222



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# File 'lib/barrier.rb', line 25

def initialize(count)
  @count_max = count
  @count = 1
  @mutex = Mutex.new
  @lock = ConditionVariable.new
end

Instance Method Details

#wait ⇒ Object

The #wait function shall synchronize participating threads at the barrier. The calling thread shall block until the required number of threads have called #wait specifying the barrier.



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# File 'lib/barrier.rb', line 35

def wait
  @mutex.synchronize do
    if @count < @count_max
      @count += 1
      @lock.wait(@mutex)
    else
      @count = 1
      @lock.broadcast
    end
  end
  nil
end