Improved tracking algorithm for upload-port reconnection

The new algorithm takes into account the case where a single board may
expose multiple ports, in this case the selection will increase priority
to ports that:

  1. have the same HW id as the user specified port for upload
  2. have the same protocol as the user specified port for upload
  3. have the same address as the user specified port for upload

Author: cmaglie

Diff for: commands/upload/upload.go

@@ -556,7 +556,6 @@ func detectUploadPort(
 	}
 
 	// Pick the first port that is detected after the upload
-	desiredHwID := uploadPort.HardwareID
 	timeout := time.After(5 * time.Second)
 	if !waitForUploadPort {
 		timeout = time.After(time.Second)
@@ -582,20 +581,41 @@ func detectUploadPort(
 				log.WithField("event", ev).Trace("Ignored non-add event")
 				continue
 			}
+
+			portPriority := func(port *discovery.Port) int {
+				if port == nil {
+					return 0
+				}
+				prio := 0
+				if port.HardwareID == uploadPort.HardwareID {
+					prio += 1000
+				}
+				if port.Protocol == uploadPort.Protocol {
+					prio += 100
+				}
+				if port.Address == uploadPort.Address {
+					prio += 10
+				}
+				return prio
+			}
+			evPortPriority := portPriority(ev.Port)
+			candidatePriority := portPriority(candidate)
+			if evPortPriority <= candidatePriority {
+				log.WithField("event", ev).Tracef("New upload port candidate is worse than the current one (prio=%d)", evPortPriority)
+				continue
+			}
+			log.WithField("event", ev).Tracef("Found new upload port candidate (prio=%d)", evPortPriority)
 			candidate = ev.Port
-			log.WithField("event", ev).Trace("New upload port candidate")
 
-			// If the current candidate port does not have the desired HW-ID do
-			// not return it immediately.
-			if desiredHwID != "" && candidate.HardwareID != desiredHwID {
-				log.Trace("New candidate port did not match desired HW ID, keep watching...")
+			// If the current candidate have the desired HW-ID return it quickly.
+			if candidate.HardwareID == ev.Port.HardwareID {
+				timeout = time.After(time.Second)
+				log.Trace("New candidate port match the desired HW ID, timeout reduced to 1 second.")
 				continue
 			}
 
-			log.Trace("Found new upload port!")
-			return
 		case <-timeout:
-			log.Trace("Timeout waiting for candidate port")
+			log.WithField("selected_port", candidate).Trace("Timeout waiting for candidate port")
 			return
 		}
 	}