class ActiveSupport::Concurrency::Latch

def await
  @lock.synchronize do
    @cv.wait_while { @count > 0 }
  end
end

def initialize(count = 1)
  @count = count
  @lock = Monitor.new
  @cv = @lock.new_cond
end

def release
  @lock.synchronize do
    @count -= 1 if @count > 0
    @cv.broadcast if @count.zero?
  end
end