guile/test-suite/tests/gc.test

;;;; gc.test --- test guile's garbage collection    -*- scheme -*-
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(use-modules (ice-9 documentation))


;;;
;;; miscellaneous
;;;


(define (documented? object)
  (not (not (object-documentation object))))

;; In guile 1.6.4 this test bombed, due to the record in h being collected
;; by the gc, but not removed from h, leaving "x" as a freed cell.
;; The usual correct result here is for x to be #f, but there's always a
;; chance gc will mark something used when it isn't, so we allow x to be a
;; record too.
(pass-if "weak-values versus records"
  (let ((rec-type (make-record-type "foo" '()))
	(h        (make-weak-value-hash-table 61)))
    (hash-set! h "foo" ((record-constructor rec-type)))
    (gc)
    (let ((x (hash-ref h "foo")))
      (or (not x)
	  ((record-predicate rec-type) x)))))

;;;
;;; 
;;;

(with-test-prefix "gc"

  (pass-if "after-gc-hook gets called"
    (let* ((foo #f)
	   (thunk (lambda () (set! foo #t))))
      (add-hook! after-gc-hook thunk)
      (gc)
      (remove-hook! after-gc-hook thunk)
      foo)))

(with-test-prefix "scm_must_realloc"

  (define (malloced-steady thunk)
    (define old-malloced -1)
    (define new-malloced -1)

    (let more ((attempt 0))
      (if (> attempt 30)
	  (begin
	    (format #t "bytes-malloced kept changing: ~a ~a\n"
		    old-malloced new-malloced)
	    #f)
	  (begin
	    (set! old-malloced new-malloced)

	    (gc)
	    (thunk)
	    (thunk)
	    (thunk)
	    (gc)
	    (gc)
	    (set! new-malloced (assoc-ref (gc-stats) 'bytes-malloced))

	    (if (= old-malloced new-malloced)
		#t
		(more (1+ attempt)))))))

  ;; In guile 1.6.7 and earlier, scm_must_realloc didn't adjust
  ;; scm_mallocated when reducing the size of a block, so when high zeros on
  ;; a bignum were trimmed by scm_i_adjbig the mallocated count ended up too
  ;; high after gc.
  ;;
  (with-test-prefix "bignum string->number trim"
    (do ((i 64 (1+ i)))
	((> i 80))
      (pass-if i
	(malloced-steady
	 (lambda ()
	   (string->number (string-append "1" (make-string i #\0)) 16)))))))