[elephant-devel] Class indexes dropped after database restart?

[Red Daly]

This bug is easy to reproduce with the latest version of elephant.
Here is some code I used to reproduce the bug:

(require :elephant)

(defpackage :ele-bug
    (:use :ele :cl))

(in-package :ele-bug)

(defclass a ()
  ((x :initarg :x :index t :initform 0 :accessor x))
  (:metaclass ele:persistent-metaclass))

(defun create-instances (n &optional (class 'a))
  (dotimes (i n)
    (make-instance class :x i)))

(defun stats ()
  (dolist (class-sym '(a b))
    (format t "~A: ~A instances; ~A with value 10~%"
	    class-sym
	    (length (get-instances-by-class class-sym))
	    (length (get-instances-by-value class-sym 'x 10)))))

(defun open-close-test ()
  (declare (optimize (debug 3)))
  (macrolet ((is (form)
	       `(assert ,form)))
    (flet ((open-it ()
	     (ele:open-store '(:bdb "db2/")))
	   (test-class-indexes (n-class n-10)
	     (is (= n-class (length (get-instances-by-class 'a))))
	     (is (= n-10    (length (get-instances-by-value 'a 'x 10))))))
      (with-open-store ('(:bdb "db2/"))
	(create-instances 100 'a)
	(test-class-indexes 100 1))
      (with-open-store ('(:bdb "db2/"))
	(test-class-indexes 100 1)))))

(open-close-test)

I was able to fix the problem with a minor patch, but I doubt the
correctness of my solution.  Here is the diff:

diff -rN old-elephant-1.0/src/elephant/controller.lisp
new-elephant-1.0/src/elephant/controller.lisp
711c711,712
<                       :key-form 'schema-classname-keyform))
---
>                       :key-form 'schema-classname-keyform
>                       :populate t))
716c717,718
<                       :key-form 'instance-cidx-keyform))))
---
>                       :key-form 'instance-cidx-keyform
>                       :populate t))))


I essentially just added a :populate t argument to the open-controller
method.  This seems to indicate that the 'BY-NAME secondary indices
that map a class indices to OIDs, and class names to class indices, do
not persist.  Is this expected behavior?  I'm not familiar enough with
the internals to tell.

Thanks,
Red





On Wed, Sep 23, 2009 at 3:27 PM, Red Daly <reddaly at gmail.com> wrote:
> This is the 1.0 repository.  I will see if I can reproduce the problem in a
> test case.
> Red
>
>
>
>
> On Sep 23, 2009, at 9:50 AM, Ian Eslick <eslick at media.mit.edu> wrote:
>
> Which darcs repository?  There is the old 0.91 release and the new
> elephant-1.0 branch...
> Ian
> On Sep 22, 2009, at 8:41 PM, Red Daly wrote:
>
> I should also note that I am using the version of elephant from darcs.  And
> I discovered that when the program went down it was due to a segfault (I
> believe in emacs).  However, all instances had been created under many
> different transactions that did not abort.
>
> Here is some more fiddling around:
>
> CL-USER> (lisp-implementation-version)
> "1.0.29.54.rc1"
> BOOKS> (ele::get-db-schemas *ele-db* 'material)
> NIL
> BOOKS> (ele::controller-instance-class-index *ele-db*)
> #<BDB-BTREE-INDEX
> oid:13701>
> BOOKS> (ele:map-btree #'(lambda (key
> val)
>                           (format t "~S => ~S~%" key
> val))
>                       (ele::controller-instance-class-index *ele-db*))
> 307 =>
> 307
> NIL
>
>
> Red
>
> On Tue, Sep 22, 2009 at 8:08 PM, Red Daly <reddaly at gmail.com> wrote:
>>
>> I noticed there was a disparity between get-instances-by-class and
>> map-inverted-index.  I will let the code speak for itself:
>>
>> BOOKS> (length (ele:map-inverted-index #'(lambda (isbn obj) obj) 'material
>> 'isbn :collect
>> t))
>>
>> 1945
>> BOOKS> (length (ele:get-instances-by-class 'material))
>> 0
>> BOOKS> (defparameter f (make-instance 'material :title "Fake Book"))
>>
>> F
>> BOOKS> (length (ele:get-instances-by-class 'material))
>>
>> 1
>> BOOKS> (length (ele:map-inverted-index #'(lambda (isbn obj) obj) 'material
>> 'isbn :collect
>> t))
>> 1946
>>
>> There is a similar problem with the university class.
>>
>> BOOKS> (length (ele:get-instances-by-class 'university))
>> 0
>> BOOKS> *stanford-university*
>> #<UNIVERSITY
>> oid:204>
>> BOOKS> (official-name *stanford-university*)
>> "Stanford University"
>>
>> All of the instances in the database were created in a prior session.
>> Then I shut down the DB and restarted Lisp.  Now MAP-CLASS and
>> GET-INSTANCES-BY-CLASS return nil for all classes.  It seems like new
>> instances get added to the "class index," but older instances are not
>> found.  However, these classes persist in the inverted slot indexes.  Can
>> anybody diagnose what's going on?
>>
>> here are the definitions of the classes:
>>
>> (defclass department ()
>>   ((university :initarg :university :initform nil :accessor
>> department-university
>>                :index t)
>>    (official-name :initarg :official-name :initform nil :accessor
>> official-name)
>>    (common-name :initarg :common-name :initform nil :accessor common-name)
>>    (abbreviation :initarg :abbreviation :initform nil :accessor
>> abbreviation
>>                  :index t))
>>   (:metaclass ele:persistent-metaclass)
>>   (:documentation "A department has a bunch of course listings."))
>>
>> (defclass material ()
>>   ((title :initarg :title :initform nil :accessor material-title
>>           :index t)
>>    (authors :initarg :authors :initform nil :accessor material-authors) ;;
>> a list of
>> authors
>>    (edition :initarg :edition :initform nil :accessor material-edition)
>>    (isbn :initarg :isbn :initform nil :accessor material-isbn
>>          :index t)
>>    (asin :initarg :asin :initform nil :accessor material-asin
>>          :index t
>>          :documentation "An Amazon.com identifier that uniquely identifies
>> the material")
>>    (image-uri :initarg :image-uri :initform nil :accessor
>> material-image-uri))
>>   (:metaclass ele:persistent-metaclass))
>>
>> Thanks,
>> Red
>>
>
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