[rucksack-devel] Re: Error when deleting indexed objects

[Brad Beveridge]

On 20/01/2008, Brad Beveridge <brad.beveridge at gmail.com> wrote:
> I've run into an error when deleting classes that have slots that are
> indexed by string.  The problem only occurs when you close & reopen
> the Rucksack before deleting, which makes me suspect it is something
> to do with the proxying.  I've tried to debug this, but I'm so far not
> getting much traction :)
> I'm going to keep looking at it, in the meantime here is a repro testcase.
>
> Cheers,
> Brad
>
> (with-rucksack (rs *test-suite* :if-exists :supersede)
>   ; Works
>   (with-transaction ()
>     (defclass broken ()
>       ((string-key :initarg :data :accessor string-key
>                    :index :string-index))
>       (:index t)
>       (:metaclass persistent-class))
>     (make-instance 'broken :data "foo1")
>     (make-instance 'broken :data "foo2")
>     (rucksack-map-class rs 'broken
>                        (lambda (obj)
>                          (format t "Found ~A~%" (string-key obj))))
>     (rucksack-map-slot rs 'broken 'string-key
>                        (lambda (obj)
>                          (rucksack::rucksack-delete-object rs obj))
>                        :equal "foo1")
>     (rucksack-map-class rs 'broken
>                        (lambda (obj)
>                          (format t "Found ~A~%" (string-key obj))))
>   ))
>
> (progn
>   ; Broken
>   (with-rucksack (rs *test-suite* :if-exists :supersede)
>     (with-transaction ()
>       (defclass broken ()
>         ((string-key :initarg :data :accessor string-key
>                      :index :string-index))
>         (:index t)
>         (:metaclass persistent-class))
>       (make-instance 'broken :data "foo1")
>       (make-instance 'broken :data "foo2")
>       (rucksack-map-class rs 'broken
>                           (lambda (obj)
>                             (format t "Found ~A~%" (string-key obj))))
>       ))
>
>   (with-rucksack (rs *test-suite*)
>     (with-transaction ()
>
>       (rucksack-map-slot rs 'broken 'string-key
>                          (lambda (obj)
>                            (rucksack::rucksack-delete-object rs obj))
>                          :equal "foo1")
>       (rucksack-map-class rs 'broken
>                           (lambda (obj)
>                             (format t "Found ~A~%" (string-key obj))))
>       )))
>
I've made some progress.  The problem is due to KEY-POSITION using
P-EQL when trying to find the position of a key in the index.  It
really should be more like
(defun key-position (btree key node)
  (p-position key (btree-node-index node)
              :key #'binding-key
	      :test (btree-key= btree)
              :end (btree-node-index-count node)))

However, that doesn't work either because the largest key in the index
will have a key of KEY-IRRELEVENT - clearly a special case.

Am I making sense here?  I guess the correct place to handle the
special case is in BTREE-KEY=

Cheers
Brad