class Steep::ThreadWaiter

def initialize(objects)
  @objects = objects
  @queue = Thread::Queue.new()
  @waiter_threads = Set[].compare_by_identity
  objects.each do |object|
    thread = yield(object)
    waiter_thread = Thread.new(thread) do |thread|
      Thread.current.report_on_exception = false
      begin
        thread.join
      ensure
        queue << [object, thread]
      end
    end
    waiter_threads << waiter_thread
  end
end

def wait_one
  unless waiter_threads.empty?
    obj, th = queue.pop()
    waiter_threads.delete(th)
    obj
  end
end