Re: [PATCH v2 12/17] python/machine: Handle QMP errors on close more meticulously

[Eric Blake]

On Wed, Sep 22, 2021 at 08:49:33PM -0400, John Snow wrote:
> To use the AQMP backend, Machine just needs to be a little more diligent
> about what happens when closing a QMP connection. The operation is no
> longer a freebie in the async world; it may return errors encountered in
> the async bottom half on incoming message receipt, etc.
> 
> (AQMP's disconnect, ultimately, serves as the quiescence point where all
> async contexts are gathered together, and any final errors reported at
> that point.)
> 
> Because async QMP continues to check for messages asynchronously, it's
> almost certainly likely that the loop will have exited due to EOF after
> issuing the last 'quit' command. That error will ultimately be bubbled
> up when attempting to close the QMP connection. The manager class here
> then is free to discard it -- if it was expected.
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> 
> ---
> 
> Yes, I regret that this class has become quite a dumping ground for
> complexity around the exit path. It's in need of a refactor to help
> separate out the exception handling and cleanup mechanisms from the
> VM-related stuff, but it's not a priority to do that just yet -- but
> it's on the list.
> 
> Signed-off-by: John Snow <jsnow@redhat.com>

This second S-o-b won't matter.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
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