Module: Kernel

Defined in:
lib/fiber_scheduler.rb

Instance Method Summary collapse

Instance Method Details

#FiberScheduler(type = nil, &block) ⇒ Object 



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# File 'lib/fiber_scheduler.rb', line 13

def FiberScheduler(type = nil, &block)
  if Fiber.scheduler.nil?
    Fiber.set_scheduler(FiberScheduler.new)

    begin
      yield
    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(type, &block)

      # Unknown fiber scheduler class; can't just pass options to
      # Fiber.schedule, handle each option separately.
    else
      scheduler.singleton_class.prepend(FiberScheduler::Compatibility)

      case type
      when :blocking
        fiber = Fiber.new(blocking: true) do
          FiberScheduler::Compatibility.set_internal!
          yield
        end
        fiber.tap(&:resume)

      when :waiting
        parent = Fiber.current
        finished = false # prevents races
        blocking = false # prevents #unblock-ing a fiber that never blocked

        fiber = Fiber.schedule do
          FiberScheduler::Compatibility.set_internal!
          yield
        ensure
          finished = true
          scheduler.unblock(nil, parent) if blocking
        end

        if Fiber.blocking?
          # In a blocking fiber, which is potentially also a loop 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
        elsif !finished
          blocking = true
          scheduler.block(nil, nil)
        end

        fiber

      when :volatile
        scheduler.unblock(nil, Fiber.current)

        fiber = Fiber.new(blocking: false) do
          FiberScheduler::Compatibility.set_internal!
          yield
        rescue FiberScheduler::Compatibility::Close
          # Fiber scheduler is closing.
        ensure
          scheduler._volatile.delete(Fiber.current)
        end
        scheduler._volatile[fiber] = nil
        fiber.tap(&:transfer)

      when nil
        Fiber.schedule do
          FiberScheduler::Compatibility.set_internal!
          yield
        end

      else
        raise "Unknown type"
      end
    end
  end
end