From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Lars Ingebrigtsen Newsgroups: gmane.emacs.bugs Subject: bug#22763: 25.1.50; Feature Request -- A faster method to obtain line number at position. Date: Sun, 07 Feb 2021 19:07:08 +0100 Message-ID: <8735y721mb.fsf@gnus.org> References: <83y4aclofm.fsf@gnu.org> <878s7z532u.fsf@gnus.org> <87y2fz3lpe.fsf@gnus.org> <87h7mn22ls.fsf@gnus.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="34002"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) Cc: 22763@debbugs.gnu.org, Keith David Bershatsky To: Stefan Monnier Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Sun Feb 07 19:08:11 2021 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1l8oTi-0008jD-Lx for geb-bug-gnu-emacs@m.gmane-mx.org; Sun, 07 Feb 2021 19:08:10 +0100 Original-Received: from localhost ([::1]:50752 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l8oTh-0008Ib-Of for geb-bug-gnu-emacs@m.gmane-mx.org; 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Original-Received: from cm-84.212.202.86.getinternet.no ([84.212.202.86] helo=xo) by quimby.gnus.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1l8oSk-0003FU-Fz; Sun, 07 Feb 2021 19:07:13 +0100 Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwBAMAAAClLOS0AAAABGdBTUEAALGPC/xhBQAAACBj SFJNAAB6JgAAgIQAAPoAAACA6AAAdTAAAOpgAAA6mAAAF3CculE8AAAAD1BMVEUkGRdVIxxoSSek Rh7////0Jn+1AAAAAWJLR0QEj2jZUQAAAAd0SU1FB+UCBQsDEP2ML4UAAAGqSURBVDjLjVOBjcMw CIR0AcALGLJAHe+/2x+4SfrSV1+kuNRnDBxnoo+myuQqrKZ9I+YOv4DwDd9gD3hdNcK89wphEsIp FqHOLJp/6X9j25zc/0AKiC+uQPLN3DMpknMW/yqXgs0DXUQ3lLoxFjurqjOKKoVRdvBXmb6wu2t+ 31TVG7jc2nwDhq4wfPx8p2kMLGITDe7z2pV1A7c5n/SYU+5rsee2zzmH7HOorPSoYp52wEW+E5iD saGxzwDYsuKkCIDKpmLhHHOYPi8AkUZmmzUAxEcCWgR4RhvpfmRJjUZOhmo67MLCyIykDx2OoeUU uPoQ9JA9boFAX904JxzT90yCwEd0quugSyYLHXMWYLMvzpMXMlSgOwuASNqqSxSOss2tiBjtZAzU OkQNS2A/Lo41HwEmxJxhDZ2eI8QQOSnIpeGhxAncJtoe2o9TAzeQsWt0UgAYyVFK/VyKwDnsjCI6 D4K7FyApdtyi9c6yFl2Cg5f0AuN6jJe4as45OD1VqUtoda/Kegt1mhdX8hrxLWldrpSA26VzJv2l +tt9U/aHh8IlDCq1/GM/Y+AwNiS2qcAAAAAldEVYdGRhdGU6Y3JlYXRlADIwMjEtMDItMDVUMTE6 MDM6MTUrMDA6MDAgZXUcAAAAJXRFWHRkYXRlOm1vZGlmeQAyMDIxLTAyLTA1VDExOjAzOjE1KzAw OjAwUTjNoAAAAABJRU5ErkJggg== X-Now-Playing: Mia Doi Todd & Company's _Music for A Midsummer Night's Dream_: "Great Love Theme in Flute" In-Reply-To: <87h7mn22ls.fsf@gnus.org> (Lars Ingebrigtsen's message of "Sun, 07 Feb 2021 18:45:51 +0100") X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:199528 Archived-At: Lars Ingebrigtsen writes: > Stefan Monnier writes: > >> Why is it faster? >> >> Is it still always =CE=98(N) just with a smaller constant (if so, what m= akes >> the constant smaller), or does it benefit from some kind of caching >> (which I fail to see in the code) such that it's O(N) sometimes but much >> faster other times (and if so, what are the cases that are sped up)? > > There's no caching. I guess find_newline is just slow compared to > display_count_lines? (How many of these functions do we have in the C > layer, anyway?) Oh, I see that find_newline has a lot of caching going on, and the logic isn't... quite... obvious. I guess it's possible there may be cases where the new implementation is slower, then? I'm not sure how to measure that, though -- it takes 10x more time to call the old `line-number-at-pos' ten times, so if the function is supposed to cache something, it's not doing that. --=20 (domestic pets only, the antidote for overdose, milk.) bloggy blog: http://lars.ingebrigtsen.no