Exemple #1
0
// WithProcessClosing returns a context.Context derived from ctx that
// is cancelled as p is Closing (after: <-p.Closing()). It is simply:
//
//   func WithProcessClosing(ctx context.Context, p goprocess.Process) context.Context {
//     ctx, cancel := context.WithCancel(ctx)
//     go func() {
//       <-p.Closing()
//       cancel()
//     }()
//     return ctx
//   }
//
func WithProcessClosing(ctx context.Context, p goprocess.Process) context.Context {
	ctx, cancel := context.WithCancel(ctx)
	go func() {
		<-p.Closing()
		cancel()
	}()
	return ctx
}
Exemple #2
0
// transport will grab message arrival times, wait until that time, and
// then write the message out when it is scheduled to arrive
func (s *stream) transport(proc process.Process) {
	bufsize := 256
	buf := new(bytes.Buffer)
	ticker := time.NewTicker(time.Millisecond * 4)

	// writeBuf writes the contents of buf through to the s.Writer.
	// done only when arrival time makes sense.
	drainBuf := func() {
		if buf.Len() > 0 {
			_, err := s.Writer.Write(buf.Bytes())
			if err != nil {
				return
			}
			buf.Reset()
		}
	}

	// deliverOrWait is a helper func that processes
	// an incoming packet. it waits until the arrival time,
	// and then writes things out.
	deliverOrWait := func(o *transportObject) {
		buffered := len(o.msg) + buf.Len()

		now := time.Now()
		if now.Before(o.arrivalTime) {
			if buffered < bufsize {
				buf.Write(o.msg)
				return
			}

			// we do not buffer + return here, instead hanging the
			// call (i.e. not accepting any more transportObjects)
			// so that we apply back-pressure to the sender.
			// this sleep should wake up same time as ticker.
			time.Sleep(o.arrivalTime.Sub(now))
		}

		// ok, we waited our due time. now rite the buf + msg.

		// drainBuf first, before we write this message.
		drainBuf()

		// write this message.
		_, err := s.Writer.Write(o.msg)
		if err != nil {
			log.Error("mock_stream", err)
		}
	}

	for {
		select {
		case <-proc.Closing():
			return // bail out of here.

		case o, ok := <-s.toDeliver:
			if !ok {
				return
			}
			deliverOrWait(o)

		case <-ticker.C: // ok, due to write it out.
			drainBuf()
		}
	}
}