Module: Kernel

Defined in:
lib/fiber_scheduler.rb

Instance Method Summary collapse

Instance Method Details

#FiberScheduler(blocking: false, waiting: true, &block) ⇒ Object 



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# File 'lib/fiber_scheduler.rb', line 12

def FiberScheduler(blocking: false, waiting: true, &block)
  if Fiber.scheduler.nil?
    scheduler = FiberScheduler.new
    Fiber.set_scheduler(scheduler)

    begin
      yield
      scheduler.close
    ensure
      Fiber.set_scheduler(nil)
    end

  else
    scheduler = Fiber.scheduler
    # Fiber.scheduler already set, just schedule a fiber.
    if scheduler.is_a?(FiberScheduler)
      # The default waiting is 'true' as that is the most intuitive behavior
      # for a nested FiberScheduler call.
      Fiber.schedule(blocking: blocking, waiting: waiting, &block)

      # Unknown fiber scheduler class; can't just pass options to
      # Fiber.schedule, handle each option separately.
    elsif blocking
      Fiber.new(blocking: true, &block).tap(&:resume)

    elsif waiting
      current = Fiber.current
      finished = false # prevents races
      Fiber.schedule do
        block.call
      ensure
        # Resume waiting parent fiber
        finished = true
        scheduler.unblock(nil, current)
      end

      if Fiber.blocking?
        # In a blocking fiber, which is potentially also a loopo fiber so
        # there's nothing we can transfer to. Run other fibers (or just
        # block) until waiting fiber finishes.
        until finished
          scheduler.run_once
        end
      else
        scheduler.block(nil, nil) unless finished
      end

    else
      Fiber.schedule(&block)
    end
  end
end