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guile/test-suite/tests/guardians.test

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;;;; guardians.test --- test suite for Guile Guardians -*- scheme -*-
;;;; Jim Blandy <jimb@red-bean.com> --- July 1999
;;;;
;;;; Copyright (C) 1999, 2001 Free Software Foundation, Inc.
;;;;
;;;; This program is free software; you can redistribute it and/or modify
;;;; it under the terms of the GNU General Public License as published by
;;;; the Free Software Foundation; either version 2, or (at your option)
;;;; any later version.
;;;;
;;;; This program is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;;; GNU General Public License for more details.
;;;;
;;;; You should have received a copy of the GNU General Public License
;;;; along with this software; see the file COPYING. If not, write to
;;;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
;;;; Boston, MA 02111-1307 USA
;;; These tests make some questionable assumptions.
;;; - They assume that a GC will find all dead objects, so they
;;; will become flaky if we have a generational GC.
;;; - They assume that objects won't be saved by the guardian until
;;; they explicitly invoke GC --- in other words, they assume that GC
;;; won't happen too often.
(use-modules (ice-9 documentation)
(ice-9 weak-vector))
;;;
;;; miscellaneous
;;;
(define (documented? object)
(not (not (object-documentation object))))
(gc)
;;; Who guards the guardian?
(gc)
(define g2 (make-guardian))
(g2 (list 'g2-garbage))
(define g3 (make-guardian))
(g3 (list 'g3-garbage))
(g3 g2)
(pass-if "g2-garbage not collected yet" (equal? (g2) #f))
(pass-if "g3-garbage not collected yet" (equal? (g3) #f))
(set! g2 #f)
(gc)
(let ((seen-g3-garbage #f)
(seen-g2 #f)
(seen-something-else #f))
(let loop ()
(let ((saved (g3)))
(if saved
(begin
(cond
((equal? saved '(g3-garbage)) (set! seen-g3-garbage #t))
((procedure? saved) (set! seen-g2 saved))
(else (set! seen-something-else #t)))
(loop)))))
(pass-if "g3-garbage saved" seen-g3-garbage)
(pass-if "g2-saved" (procedure? seen-g2))
(pass-if "nothing else saved" (not seen-something-else))
(pass-if "g2-garbage saved" (and (procedure? seen-g2)
(equal? (seen-g2) '(g2-garbage)))))
(with-test-prefix "standard guardian functionality"
(with-test-prefix "make-guardian"
(pass-if "documented?"
(documented? make-guardian))
(pass-if "returns procedure"
(procedure? (make-guardian)))
(pass-if "returns new procedure each time"
(not (equal? (make-guardian) (make-guardian)))))
(with-test-prefix "empty guardian"
(pass-if "returns #f"
(eq? ((make-guardian)) #f))
(pass-if "returns always #f"
(let ((g (make-guardian)))
(and (eq? (g) #f)
(begin (gc) (eq? (g) #f))
(begin (gc) (eq? (g) #f))))))
(with-test-prefix "guarding independent objects"
(pass-if "guarding immediate"
(let ((g (make-guardian)))
(g #f)
(and (eq? (g) #f)
(begin (gc) (eq? (g) #f))
(begin (gc) (eq? (g) #f)))))
(pass-if "guarding non-immediate"
(let ((g (make-guardian)))
(gc)
(g (cons #f #f))
(if (not (eq? (g) #f))
(throw 'unresolved)
(begin
(gc)
(if (not (equal? (g) (cons #f #f)))
(throw 'unresolved)
(eq? (g) #f))))))
(pass-if "guarding two non-immediates"
(let ((g (make-guardian)))
(gc)
(g (cons #f #f))
(g (cons #t #t))
(if (not (eq? (g) #f))
(throw 'unresolved)
(begin
(gc)
(let ((l (list (g) (g))))
(if (not (or (equal? l (list (cons #f #f) (cons #t #t)))
(equal? l (list (cons #t #t) (cons #f #f)))))
(throw 'unresolved)
(eq? (g) #f)))))))
(pass-if "re-guarding non-immediates"
(let ((g (make-guardian)))
(gc)
(g (cons #f #f))
(if (not (eq? (g) #f))
(throw 'unresolved)
(begin
(gc)
(let ((p (g)))
(if (not (equal? p (cons #f #f)))
(throw 'unresolved)
(begin
(g p)
(set! p #f)
(gc)
(if (not (equal? (g) (cons #f #f)))
(throw 'unresolved)
(eq? (g) #f)))))))))
(pass-if "guarding living non-immediate"
(let ((g (make-guardian))
(p (cons #f #f)))
(g p)
(if (not (eq? (g) #f))
(throw 'fail)
(begin
(gc)
(not (eq? (g) p)))))))
(with-test-prefix "guarding weakly referenced objects"
(pass-if "guarded weak vector element gets returned from guardian"
(let ((g (make-guardian))
(v (weak-vector #f)))
(gc)
(let ((p (cons #f #f)))
(g p)
(vector-set! v 0 p))
(if (not (eq? (g) #f))
(throw 'unresolved)
(begin
(gc)
(if (not (equal? (g) (cons #f #f)))
(throw 'unresolved)
(eq? (g) #f))))))
(pass-if "guarded element of weak vector gets removed from weak vector"
;; How should this be handled? Should weak objects be removed from
;; their containers before they become zombies? Let's take a look at
;; the possible scenarios: a) Weak objects that are also guarded are
;; not removed from their containers as long as they are guarded.
;; However, they still can become zombies. The consequence is, that the
;; object can be retrieved from its container, thus being alive, while
;; on the other hand it can at the same time be retrieved from a
;; guardian. This is unfortunate, since when retrieving an object from
;; a guardian one would not expect any other reference to the object.
;; b) Weak objects are removed from their containers if they are not
;; referenced any more or if the only references are from guardians.
;; That means that it is guaranteed that there are no other references
;; to an object that is retrieved from a guardian. However, this means
;; that there is no chance to update containers like weak hash tables
;; using the information that one of their contained objects will be
;; removed. It may be however, that this is not necessary anyway.
(let ((g (make-guardian))
(v (weak-vector #f)))
(gc)
(let ((p (cons #f #f)))
(g p)
(vector-set! v 0 p))
(if (not (equal? (vector-ref v 0) (cons #f #f)))
(throw 'unresolved)
(begin
(gc)
(if (equal? (vector-ref v 0) (cons #f #f))
(throw 'unresolved)
#t))))))
(with-test-prefix "guarding weak containers"
(pass-if "element of guarded weak vector gets collected"
(let ((g (make-guardian))
(v (weak-vector (cons #f #f))))
(g v)
(gc)
(if (equal? (vector-ref v 0) (cons #f #f))
(throw 'unresolved)
#t))))
(with-test-prefix "guarding guardians"
#t))
(with-test-prefix "guile guardian functionality"
(with-test-prefix "guarding dependent objects"
(pass-if "guarding vector and element"
(let ((g (make-guardian)))
(gc)
(let ((p (cons #f #f)))
(g p)
(g (vector p)))
(if (not (eq? (g) #f))
(throw 'unresolved)
(begin
(gc)
(if (not (equal? (g) (vector (cons #f #f))))
(throw 'unresolved)
(if (not (eq? (g) #f))
(throw 'unresolved)
(begin
(gc)
(if (not (equal? (g) (cons #f #f)))
(throw 'unresolved)
(eq? (g) #f)))))))))
)
(with-test-prefix "guarding objects more than once"
#t)
(with-test-prefix "guarding cyclic dependencies"
#t)
)