[tor-bugs] #6234 [Stem]: stem.socket.ControlSocket.is_alive() should check if socket is open explicitly

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#6234: stem.socket.ControlSocket.is_alive() should check if socket is open
explicitly
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    Reporter:  gsathya  |       Owner:  atagar           
        Type:  defect   |      Status:  needs_information
    Priority:  normal   |   Milestone:                   
   Component:  Stem     |     Version:                   
  Resolution:           |    Keywords:                   
      Parent:           |      Points:                   
Actualpoints:           |  
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Comment(by atagar):

 That makes sense. The is_alive() method works as follows...
 - is_alive() simply provides the cached is_alive status (ie, what do we
 think we are?)
 - our is_alive flag toggles when connect() or close() is called
 - our close() is called when we attempt to read from our socket and it
 reports that the socket is closed

 So, when you call 'QUIT' the controller sends the message, receives an OK
 reply then returns to the caller. Meanwhile the reader loop pulls the
 socket again and (possibly delayed by tor or the os) sees that our socket
 is shut down and calls close() to clean up.

 Obviously to make the 'QUIT' case work we could simply call close()
 ourselves before returning. It would be a bug if our is_alive() state
 didn't change for a significant amount of time, but is_alive() just
 reflects 'do I seem to be alive at this instant'. We could acquire the
 read lock to narrow the gap, but that doesn't seem like a good idea and
 wouldn't completely eliminate this "'QUIT' -> is_alive() is false" gap.

 So in summary, I think that having our quit() method call close() is
 probably the best option. Let me know if you strongly disagree.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/6234#comment:10>
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