Okay, here's an alternate method.

 When a user needs to save their note
  If the note is already saving
   Set note.saveAgain = true
  else
   Start the process of saving the note
 
 When the note has saved
  If note.saveAgain == true
   Set note.saveAgain = false
   Start the process of saving the note again

That doesn't require a queue. It also only saves the most up to date version.