[tahoe-lafs-trac-stream] [tahoe-lafs] #1670: KeyError in mutable read-modify-write

[tahoe-lafs]

#1670: KeyError in mutable read-modify-write
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     Reporter:  vikarti  |      Owner:  zooko
         Type:  defect   |     Status:  assigned
     Priority:  major    |  Milestone:  1.11.0
    Component:  code-    |    Version:  1.9.1
  mutable                |   Keywords:  mutable retrieve error tahoe-backup
   Resolution:           |  regression test-needed preservation
Launchpad Bug:           |
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Comment (by daira):

 Replying to [comment:9 kevan]:
 > It looks like the mutable filenode modification code in
 {{{MutableFileVersion}}} reacts to an {{{UncoordinatedWriteError}}} by
 performing a map update, then trying the operation again. That map update
 will update the {{{MutableFileVersion}}}'s internal servermap, but not its
 internal verinfo tuple. If the {{{UncoordinatedWriteError}}} is due to a
 concurrent update operation that updated all or most (enough for the
 version to be unrecoverable, anyway) of the shares associated with the
 {{{MutableFileVersion}}}'s version of the mutable file, then we would see
 the {{{KeyError}}} reported by vikarti and others.

 So, isn't the correct fix for this, without making any design changes,
 just for {{{Mutable FileVersion}}} to make sure that its verinfo type is
 also updated when it does a mapupdate in this case?

-- 
Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1670#comment:41>
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