[elephant-devel] map-btree from-end arg not working?

[Robert L. Read]

Thanks for looking at that, Ian.

The extensive test suite which the original authors started and Ian and
I have improved gives us a lot of leverage here; if the change keeps us
green on all tests then we are probably safe.

On Sat, 2007-09-08 at 15:49 -0400, Ian Eslick wrote:
> Let me look at the history for that file.  I can't remember if I  
> fixed some of this on the working branch (darcs) or back during the  
> 0.9.0 release.  There are a bunch of subtle interactions that can  
> disturb each other, but that does look like a problem doesn't it?
> 
> Ian
> 
> 
> On Sep 8, 2007, at 3:28 PM, Chris Laux wrote:
> 
> > So I had a look at it myself and it turned out to be much easier  
> > than I
> > had expected, which is what kept me from trying in the first place.
> >
> > The following method in src/db-bdb/bdb-collections.lisp is the  
> > culprit:
> >
> > (defmethod cursor-prev ((cursor bdb-cursor))
> >   (if (cursor-initialized-p cursor)
> >       (let ((sc (get-con (cursor-btree cursor))))
> > 	(with-buffer-streams (key-buf value-buf)
> > 	  (multiple-value-bind (key val)
> > 	      (db-cursor-move-buffered (cursor-handle cursor)
> > 				       key-buf value-buf :prev t)
> > 	    (if (and key (= (buffer-read-oid key) (cursor-oid cursor)))
> > 		(values t (deserialize key sc)
> > 			(deserialize val sc))
> > 		(setf (cursor-initialized-p cursor) nil))))
> > 	(cursor-last cursor))))
> >
> > That "cursor-last" call at the end looks very suspicious, and indeed
> > removing it solves the problem. But I don't know where it belongs  
> > or if
> > it can be safely removed. Any ideas?
> >
> > Cheers,
> >
> > Chris Laux
> >
> >
> > Chris Laux wrote:
> >> Hi again,
> >>
> >> I seem to have stumbled across another bug: the from-end argument
> >> doesn't seem to be working, map-btree always calls with the same
> >> (presumably last) entry when it is set.
> >>
> >> (defun test-btree-from-end (btree from-end)
> >>   (let (acc
> >> 	(n 0))
> >>     (map-btree #'(lambda (k v)
> >> 		   (push (list k v) acc)
> >> 		   (when (= (incf n) 4)
> >> 		     (return-from test-btree-from-end acc)))
> >> 	       btree :from-end from-end)))
> >>
> >>> (test-btree-from-end ** nil)
> >> ((3398012969 #<MESSAGE oid:227324>) (3398012898 #<MESSAGE oid: 
> >> 226751>)
> >>  (3398012815 #<MESSAGE oid:226044>) (3398012772 #<MESSAGE oid: 
> >> 225621>))
> >>
> >>> (test-btree-from-end *** t)
> >> ((3398231130 #<MESSAGE oid:552110>) (3398231130 #<MESSAGE oid: 
> >> 552110>)
> >>  (3398231130 #<MESSAGE oid:552110>) (3398231130 #<MESSAGE oid: 
> >> 552110>))
> >>
> >> My setup is BerkeleyDB 4.5.20 with Elephant 0.9.0 with SBCL 1.0.4 on
> >> Linux/x86-64.
> >>
> >> Thanks,
> >>
> >> Chris Laux
> >>
> > _______________________________________________
> > elephant-devel site list
> > elephant-devel at common-lisp.net
> > http://common-lisp.net/mailman/listinfo/elephant-devel
> 
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