[spambayes-dev] Help: bsddb._db.DBAccessError: (13, 'Permission denied -- put: attempt to modify a read-only tree') in<bound method HammieFilter.close ...

[David Abrahams]

on Sun Jul 29 2007, David Abrahams <dave-UB3wUj7V41K5azolltMz9laTQe2KTcn/-AT-public.gmane.org> wrote:

> on Thu Jul 26 2007, "Mark Hammond" <mhammond-bte8sPG7QFgW+bLBXbPJGg-AT-public.gmane.org> wrote:
>
>>> This bug appears to be back in some form:
>>> http://sourceforge.net/tracker/index.php?func=detail&aid=13876
>>> 99&group_id=61702&atid=498103
>>
>> Its hard to know if that fix was applied, as there is no attachement with
>> the patch.  Hopefully Tony will notice this thread and pipe up.
>>
>>> I was unable to reopen the tracker item.  Can someone help me to at
>>> least debug this problem?  When exceptions are swallowed like that
>>> without a backtrace, I don't know where to start.
>>
>> I'm guessing the vanishing backtrace is due to it being called by __del__.
>> It *looks* like it might be __del__ in sb_filter.py.  However, it looks a
>> little like your exception is slightly different than the backtrace in that
>> bug - the bug refers to an error adding tokens to the DB after training,
>> while your exception sounds more like an exception as the DB is closed.
>
> Yes, after hacking __del__ to dump a backtrace, I see:
>
> Traceback (most recent call last):
>   File "/usr/local/bin/sb_filter.py", line 185, in __del__
>     self.close()
>   File "/usr/local/bin/sb_filter.py", line 180, in close
>     self.h.close()
>   File "/usr/local/lib/python2.4/site-packages/spambayes/hammie.py", line 269, in close
>     self.store()
>   File "/usr/local/lib/python2.4/site-packages/spambayes/hammie.py", line 266, in store
>     self.bayes.store()
>   File "/usr/local/lib/python2.4/site-packages/spambayes/storage.py", line 266, in store
>     self._write_state_key()
>   File "/usr/local/lib/python2.4/site-packages/spambayes/storage.py", line 270, in _write_state_key
>     self.db[self.statekey] = (classifier.PICKLE_VERSION,
>   File "/usr/local/lib/python2.4/shelve.py", line 130, in __setitem__
>     self.dict[key] = f.getvalue()
>   File "/usr/local/lib/python2.4/site-packages/bsddb3/__init__.py", line 218, in __setitem__
>     self.db[key] = value
> DBAccessError: (13, 'Permission denied -- put: attempt to modify a read-only tree')
>
>
> My analysis is as follows: HammieFilter.close (in sb_filter.py) jumps through
> all sorts of hoops to remember the mode in which the DB was opened, and
> avoid calling store() if it was only opened for read.  
>
>     def close(self):
>         if self.h is not None:
>             if self.mode != 'r':
>                 self.h.store()
>             self.h.close()
>         self.h = None
>
> So it sorta looks like Tony's patch was applied.
>
> However, Hammie.close (in hammie.py) just barrels ahead and calls
> store() unconditionally...
>
> I'm not sure what the right fix here would be.  Keep HammieFilter from
> calling Hammie.close() when the DB was not opened for write?  Sink the
> close/store/mode-checking logic from HammieFilter into Hammie itself?
> Something else?

Okay, I submitted a simple patch.  I hope someone can look it over.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com

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