>>45,46
Thanks for the repo update.
so they should be safe
OK, then. I see that string->number returns #f on invalid inputs, so >>44 and similar are harmless 404s. A resource utilization test for string->number:
>>> ">>1-" + "9" * (4096 - 4)Since irregex claims to support PCRE ranges
http://synthcode.com/scheme/irregex/#SECTION_3.3
if this causes a spike it can be mitigated by switching the range regex numbers from [1-9][0-9]* to [1-9][0-9]{0,2} with the limit raised when *max-posts* gains digits.
I also have a nerd rant about filter-func/posts-range design for another post.
[1/2]
Since your BIOS is being a Basic Inducer Of Suffering, here is an implementation of >>57 to eliminate delete-duplicates, in the MIT/GNU Scheme 9.1.1 from the Ubuntu LTS, while keeping as much of your structure as possible:
(define (posts-range range)
(define (expand-range x)
(cond ((> (length x) 1)
(let* ((a (string->number (car x)))
(b (string->number (cadr x)))
(low (if (> a *max-posts*) *max-posts* a))
(high (if (> b *max-posts*) *max-posts* b))
(count (+ (- high low) 1)))
(if (> high low)
(lambda () (iota count low))
(lambda () (list low)))))
(else (let* ((a (string->number (car x)))
(low (if (> a *max-posts*) *max-posts* a)))
(lambda () (list low))))))
(define (invoke-loop-set vector lamb)
(for-each (lambda (e) (vector-set! vector e #t))
(lamb)))
(let* ((r1 (string-split range #\,))
(r2 (map (lambda (x) (string-split x #\-)) r1))
(r3 (map expand-range r2))
(vec (make-vector (+ *max-posts* 1) #f)))
(for-each (lambda (e) (invoke-loop-set vec e))
r3)
vec))Here are some tests, keeping in mind that posts-range runs after the regex match:
1 ]=> (posts-range "1,3,5,7,290-300")
;Value 13: #(#f #t #f #t #f #t #f #t #f #f #f #f [...] #f #f #f #f #t #t #t #t #t #t #t #t #t #t #t)
1 ]=> (posts-range "1-9999999999")
;Value 14: #(#f #t #t #t #t #t #t #t #t #t #t #t [...] #t #t #t #t #t #t #t #t #t #t #t #t #t #t #t)
1 ]=> (define fulltest (apply string-append (cons "1-300" (make-list (quotient (- 4096 7) 6) ",1-300"))))At this point fulltest is >>50.
1 ]=> (posts-range fulltest)
;Value 17: #(#f #t #t #t #t #t #t #t #t #t #t #t [...] #t #t #t #t #t #t #t #t #t #t #t #t #t #t #t)
1 ]=> (define (timeit proc)
(with-timings proc
(lambda (run-time gc-time real-time)
(write (internal-time/ticks->seconds run-time))
(write-char #\space)
(write (internal-time/ticks->seconds gc-time))
(write-char #\space)
(write (internal-time/ticks->seconds real-time))
(newline))))
1 ]=> (timeit (lambda () (posts-range "1,3,5,7,290-300")))
0. 0. 0.
1 ]=> (timeit (lambda () (posts-range fulltest)))
.04 0. .044[2/2]
The time for fulltest fluctuates between 4 and 5 centiseconds, but since the homepage has:
Runs well on "el cheapo" VPS
I recommend both regex refinements as well. To integrate with filter-func, here is a diff against the current gitlab version, which is the last commit of "20 Feb, 2020". This one is untested because I do not yet have a local instance, but it is simple enough that it should work.
$ TZ=GMT diff -u schemebbs/bbs.scm edit/bbs.scm
--- schemebbs/bbs.scm 2020-02-20 15:17:38.682224678 +0000
+++ edit/bbs.scm 2020-02-22 14:41:02.198743998 +0000
@@ -138,10 +138,12 @@
(let* ((t (call-with-input-file path read))
(headline (lookup-def 'headline t))
(posts (lookup-def 'posts t))
- (filter-func (if (default-object? range)
- identity
- (lambda (e) (member (car e) (posts-range range))))))
- (cond ((default-object? range)
+ (norange (default-object? range))
+ (rangeonce (if norange "unused" (posts-range range)))
+ (filter-func (if norange
+ (lambda (e) #t)
+ (lambda (e) (vector-ref rangeonce (car e))))))
+ (cond (norange
(if (not (file-exists? cache))
(write-and-serve cache (thread-template board thread posts headline filter-func))
(begin (display "reverse proxy miss") (serve-file cache)))) ;; we shouldn't go here, reverse proxy fetches the page itselfHere are the two regex refinements for digit count >>47 and interval count >>49. The SYNCs are there for grep. The irregex PCRE ranges are linked in >>47.
$ TZ=GMT diff -u schemebbs/bbs.scm edit/bbs.scm
--- schemebbs/bbs.scm 2020-02-20 15:17:38.682224678 +0000
+++ edit/bbs.scm 2020-02-22 15:40:23.041388774 +0000
@@ -153,7 +153,9 @@
(define (range? posts)
- (irregex-match "([1-9][0-9]*|([1-9][0-9]*)-([1-9][0-9]*))(,([1-9][0-9]*|([1-9][0-9]*-[1-9][0-9]*)))*" posts))
+ (irregex-match "(([1-9][0-9]{0,2})|(([1-9][0-9]{0,2})-([1-9][0-9]{0,2})))(,(([1-9][0-9]{0,2})|(([1-9][0-9]{0,2})-([1-9][0-9]{0,2})))){0,11}" posts))
+ ; SYNC lib/markup.scm:quotelink
+ ; SYNC digit count of *max-posts*
(define (posts-range range)
(define (expand-range x)
$ TZ=GMT diff -u schemebbs/lib/markup.scm edit/lib/markup.scm
--- schemebbs/lib/markup.scm 2020-02-20 15:17:38.682224678 +0000
+++ edit/lib/markup.scm 2020-02-22 15:38:37.134770741 +0000
@@ -182,7 +182,8 @@
(define quotelink
(transform-rule
'quotelink
- (irregex ">>([1-9][0-9]*|([1-9][0-9]*)-([1-9][0-9]*))(,([1-9][0-9]*|([1-9][0-9]*-[1-9][0-9]*)))*")
+ (irregex ">>(([1-9][0-9]{0,2})|(([1-9][0-9]{0,2})-([1-9][0-9]{0,2})))(,(([1-9][0-9]{0,2})|(([1-9][0-9]{0,2})-([1-9][0-9]{0,2})))){0,11}")
+ ; SYNC bbs.scm:range?
(lambda (sub) `(a (@ (href ,(string-append
"/" *board*
"/" *thread*With all of the above applied, the maximum stress that can be put on posts-range is:
1 ]=> (define maxtest (apply string-append (cons "1-300" (make-list 11 ",1-300"))))
1 ]=> (posts-range maxtest)which runs in zero time.
>>1-300,1-300,1-300,1-300,1-300,1-300,1-300,1-300,1-300,1-300,1-300,1-300
If the server machine is an honest-to-God potato, the 11 can be further reduced.
>>64-67
Wow! Thanks for the patches. I can't express my gratitude enough in those apocalyptic times. (I just managed to have a working system again, I'm installing MIT Scheme 9.2 and will detail the long overdue installation of SchemeBBS)
While the regex seems correct when I try it at the REPL, there's a weird bug with the transform rule, as in >>65:
>>1,10-20,30
I have to sort this out.