[monitor-assign] Unassign devices from a monitor before leaving

When a monitor leaves the system, it now first unassigns all devices it has,
then deregisters from the list and quits.

The previous behaviour, for which it would just deregister and quit, meant it
left outdated assignations in the database, that some other monitor would have
to clean.
Signed-off-by: Roger Pueyo Centelles <rpueyo@ac.upc.edu>

monitor-assign/monitor-assign.go

@@ -112,9 +112,29 @@ func main() {
 	signal.Notify(signalChan, os.Interrupt)
 	go func() {
 		for _ = range signalChan {
-			fmt.Println("\nReceived an interrupt, deregistering from the monitors list and quitting...")
 
+			if len(localAssign) > 0 {
+				if len(localAssign) > 1 {
+					fmt.Println("\nReceived an interrupt, unassigning", len(localAssign), "devices from this monitor before quitting...")
+				} else {
+					fmt.Println("\nReceived an interrupt, unassigning 1 device from this monitor before quitting...")
+				}
+				var unassigned = 0
+				for _, v := range localAssign {
+					if unassignMonitorFromDevice(ID, v.Device.ID) {
+						unassigned = unassigned + 1
+					}
+				}
+				if unassigned == 1 && len(localAssign) == 1 {
+					fmt.Println("1 device out of 1 successfully unassigned.")
+				} else {
+					fmt.Println(unassigned, "devices out of", len(localAssign), "successfully unassigned.")
+				}
+			}
+
+			fmt.Println("Deregistering from the monitors list...")
 			deregisterMonitorInAntidote(ID)
+
 			cleanupDone <- true
 		}
 	}()