From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.1 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 4AE7120133 for ; Thu, 2 Mar 2017 09:00:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754314AbdCBJAV (ORCPT ); Thu, 2 Mar 2017 04:00:21 -0500 Received: from cloud.peff.net ([104.130.231.41]:37081 "EHLO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754216AbdCBJAC (ORCPT ); Thu, 2 Mar 2017 04:00:02 -0500 Received: (qmail 24561 invoked by uid 109); 2 Mar 2017 08:53:15 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.84) with SMTP; Thu, 02 Mar 2017 08:53:15 +0000 Received: (qmail 15509 invoked by uid 111); 2 Mar 2017 08:53:22 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.84) with SMTP; Thu, 02 Mar 2017 03:53:22 -0500 Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Thu, 02 Mar 2017 03:53:13 -0500 Date: Thu, 2 Mar 2017 03:53:13 -0500 From: Jeff King To: Junio C Hamano Cc: tboegi@web.de, git@vger.kernel.org, mac@mcrowe.com Subject: Re: [PATCH v1 1/1] git diff --quiet exits with 1 on clean tree with CRLF conversions Message-ID: <20170302085313.r6dox4wa2kqnp7ao@sigill.intra.peff.net> References: <20170301170444.14274-1-tboegi@web.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Wed, Mar 01, 2017 at 01:54:26PM -0800, Junio C Hamano wrote: > -- >8 -- > Subject: [PATCH] diff: do not short-cut CHECK_SIZE_ONLY check in diff_populate_filespec() Thanks, this is well-explained, and the new comments in the code really help. I wondered if we should be checking would_convert_to_git() in reuse_worktree_file(), but we already do. It's just that we may still end up in this code-path when we're _actually_ diffing the working tree file, not just trying to optimize. > diff --git a/diff.c b/diff.c > index 8c78fce49d..dc51dceb44 100644 > --- a/diff.c > +++ b/diff.c > @@ -2792,8 +2792,25 @@ int diff_populate_filespec(struct diff_filespec *s, unsigned int flags) > s->should_free = 1; > return 0; > } > - if (size_only) > + > + /* > + * Even if the caller would be happy with getting > + * only the size, we cannot return early at this > + * point if the path requires us to run the content > + * conversion. > + */ > + if (!would_convert_to_git(s->path) && size_only) > return 0; The would_convert_to_git() function is a little expensive (it may have to do an attribute lookup). It may be worth swapping the two halves of the conditional here to get the short-circuit. It may not matter much in practice, though, because in the !size_only case we'd make the same query lower a few lines later (and in theory expensive bits of the attr lookup are cached). > + > + /* > + * Note: this check uses xsize_t(st.st_size) that may > + * not be the true size of the blob after it goes > + * through convert_to_git(). This may not strictly be > + * correct, but the whole point of big_file_threashold s/threashold/threshold/ > + * and is_binary check being that we want to avoid > + * opening the file and inspecting the contents, this > + * is probably fine. > + */ > if ((flags & CHECK_BINARY) && > s->size > big_file_threshold && s->is_binary == -1) { > s->is_binary = 1; I'm trying to think how this "not strictly correct" could bite us. For line-ending conversion, I'd say that the before/after are going to be approximately the same size. But what about something like LFS? If I have a 600MB file that convert_to_git() filters into a short LFS pointer, I think this changes the behavior. Before, we would diff the pointer file, but now we'll get "binary file changed". I wonder if we should take the opposite approach, and ignore big_file_threshold for converted files. One assumes that such gigantic files are binary, and therefore do not have line endings to convert. And any filtering has a reasonable chance of condensing them to something much smaller. I dunno. I'm sure somebody has some horrific 500MB-filtering example that can prove me wrong. -Peff