[tahoe-dev] [tahoe-lafs] #1223: got 'WrongSegmentError' during repair

tahoe-lafs trac at tahoe-lafs.org
Mon Oct 18 19:13:40 UTC 2010

#1223: got 'WrongSegmentError' during repair
     Reporter:  francois       |       Owner:  somebody                     
         Type:  defect         |      Status:  new                          
     Priority:  major          |   Milestone:  1.8.1                        
    Component:  code-encoding  |     Version:  1.8.0                        
   Resolution:                 |    Keywords:  regression repair performance
Launchpad Bug:                 |  

Comment (by warner):

 this patch adds a test and fixes the issue. I'd like another pair of
 eyeballs on it, specifically because it changes the way that
 {{{read_encrypted}}} is called (segment-at-a-time instead of
 inputchunksize-at-a-time), and I'm concerned about inducing a fencepost
 error. But I think this new approach is a lot better: fewer reads, about
 the same memory footprint, remove some recursion. The only tiny drawback
 is that Uploadables (and other things that provide {{{read_encrypted()}}},
 like the Repairer, and the Offloaded uploadable) are now constrained to
 act more like regular disk files: if you do a {{{read_encrypted(123)}}},
 they are obligated to give you exactly 123 bytes, unless you're at EOF, in
 which case they can give you less than you asked for exactly once.
 Previously we weren't imposing this requirement, allowing Uploadables to
 return random amounts of data on each {{{read_encrypted()}}} call.

Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1223#comment:12>
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