class RubyProf::Thread

def wait_time
  # wait_time, like self:time, is always method local

  # thus we need to sum over all methods and call infos

  self.methods.inject(0) do |sum, method_info|
    method_info.callers.each do |call_tree|
      sum += call_tree.wait_time
    end
    sum
  end
end