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From: Junio C Hamano <gitster@pobox•com>
To: "Ezekiel Newren via GitGitGadget" <gitgitgadget@gmail•com>
Cc: git@vger•kernel.org,  Elijah Newren <newren@gmail•com>,
	 Ezekiel Newren <ezekielnewren@gmail•com>
Subject: Re: [PATCH 6/7] xdiff: conditionally use Rust's implementation of xxhash
Date: Fri, 18 Jul 2025 12:00:36 -0700	[thread overview]
Message-ID: <xmqqzfd12ujv.fsf@gitster.g> (raw)
In-Reply-To: <5a959c9bdad79cf972b95dcf4324135dd7c94dac.1752784344.git.gitgitgadget@gmail.com> (Ezekiel Newren via GitGitGadget's message of "Thu, 17 Jul 2025 20:32:23 +0000")

"Ezekiel Newren via GitGitGadget" <gitgitgadget@gmail•com> writes:

> +extern u64 xxh3_64(u8 const* ptr, usize size);
> +
> +
>  static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_t const *xpp,
>  			   xdlclassifier_t *cf, xdfile_t *xdf) {
>  	unsigned long *ha;
> @@ -175,14 +178,26 @@ static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_
>  
>  	xdl_parse_lines(mf, narec, xdf);
>  
> +	if ((xpp->flags & XDF_WHITESPACE_FLAGS) == 0) {
> +		for (usize i = 0; i < (usize) xdf->nrec; i++) {
> +			xrecord_t *rec = xdf->recs[i];
> +			rec->ha = xxh3_64(rec->ptr, rec->size);
> +		}
> +	} else {
> +		for (usize i = 0; i < (usize) xdf->nrec; i++) {
> +			xrecord_t *rec = xdf->recs[i];
> +			char const* dump = (char const*) rec->ptr;
> +			rec->ha = xdl_hash_record(&dump, (char const*) (rec->ptr + rec->size), xpp->flags);
> +		}
> +	}

As a technology demonstration and proof of concept patch, this is
very nice, but to be upstreamed for real, we'd want a variant of
xxhash that can work with the contents with whitespace squashed to
be usable with various whitespace ignoring modes of operation.  When
that happens, and when the result turns out to be more performant,
we can lose the xdl_hash_record() and require only the xxhash, which
would be great.

And that variant of xxhash that understands whitespace squashing can
of course be written in Rust as a part of this effort when the
series loses its RFC status.  At the same time, those who want to
use our xdiff code in third-party software (like libgit2 and vim)
may want to reimplement it in C in their copy.

Thanks.


  parent reply	other threads:[~2025-07-18 19:00 UTC|newest]

Thread overview: 204+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-17 20:32 [PATCH 0/7] RFC: Accelerate xdiff and begin its rustification Ezekiel Newren via GitGitGadget
2025-07-17 20:32 ` [PATCH 1/7] xdiff: introduce rust Ezekiel Newren via GitGitGadget
2025-07-17 21:30   ` brian m. carlson
2025-07-17 21:54     ` Junio C Hamano
2025-07-17 22:39     ` Taylor Blau
2025-07-18 23:15     ` Ezekiel Newren
2025-07-23 21:57       ` brian m. carlson
2025-07-23 22:26         ` Junio C Hamano
2025-07-28 19:11         ` Ezekiel Newren
2025-07-31 22:37           ` brian m. carlson
2025-07-22 22:02     ` Mike Hommey
2025-07-22 23:52       ` brian m. carlson
2025-07-17 22:38   ` Taylor Blau
2025-07-17 20:32 ` [PATCH 2/7] xdiff/xprepare: remove superfluous forward declarations Ezekiel Newren via GitGitGadget
2025-07-17 22:41   ` Taylor Blau
2025-07-17 20:32 ` [PATCH 3/7] xdiff: delete unnecessary fields from xrecord_t and xdfile_t Ezekiel Newren via GitGitGadget
2025-07-17 20:32 ` [PATCH 4/7] xdiff: make fields of xrecord_t Rust friendly Ezekiel Newren via GitGitGadget
2025-07-17 22:46   ` Taylor Blau
2025-07-17 23:13     ` brian m. carlson
2025-07-17 23:37       ` Elijah Newren
2025-07-18  0:23         ` Taylor Blau
2025-07-18  0:21       ` Taylor Blau
2025-07-18 13:35   ` Phillip Wood
2025-07-28 19:34     ` Ezekiel Newren
2025-07-28 19:52       ` Phillip Wood
2025-07-28 20:14         ` Ezekiel Newren
2025-07-31 14:20           ` Phillip Wood
2025-07-31 20:58             ` Ezekiel Newren
2025-08-01  9:14               ` Phillip Wood
2025-07-28 20:53         ` Junio C Hamano
2025-07-28 20:00       ` Collin Funk
2025-07-20  1:39   ` Johannes Schindelin
2025-07-17 20:32 ` [PATCH 5/7] xdiff: separate parsing lines from hashing them Ezekiel Newren via GitGitGadget
2025-07-17 22:59   ` Taylor Blau
2025-07-18 13:34   ` Phillip Wood
2025-07-17 20:32 ` [PATCH 6/7] xdiff: conditionally use Rust's implementation of xxhash Ezekiel Newren via GitGitGadget
2025-07-17 23:29   ` Taylor Blau
2025-07-18 19:00   ` Junio C Hamano [this message]
2025-07-31 21:13     ` Ezekiel Newren
2025-08-02  7:53       ` Matthias Aßhauer
2025-07-19 21:53   ` Johannes Schindelin
2025-07-20 10:14     ` Phillip Wood
2025-09-23  9:57       ` gitoxide-compatible licensing of Git's Rust code, was " Johannes Schindelin
2025-09-23 17:48         ` Jeff King
2025-09-24 13:48           ` Phillip Wood
2025-09-25  2:25             ` Jeff King
2025-09-25  5:42               ` Patrick Steinhardt
2025-09-26 10:06               ` Phillip Wood
2025-10-03  3:18                 ` Jeff King
2025-10-03  9:51                   ` Phillip Wood
2025-10-07  9:11                     ` Patrick Steinhardt
2025-11-17 13:37                     ` Johannes Schindelin
2025-10-05  5:32       ` Yee Cheng Chin
2025-07-17 20:32 ` [PATCH 7/7] github_workflows: install rust Ezekiel Newren via GitGitGadget
2025-07-17 21:23   ` brian m. carlson
2025-07-18 23:01     ` Ezekiel Newren
2025-07-25 23:56       ` Ben Knoble
2025-07-19 21:54   ` Johannes Schindelin
2025-07-17 21:51 ` [PATCH 0/7] RFC: Accelerate xdiff and begin its rustification brian m. carlson
2025-07-17 22:25   ` Taylor Blau
2025-07-18  0:29     ` brian m. carlson
2025-07-22 12:21       ` Patrick Steinhardt
2025-07-22 15:56         ` Junio C Hamano
2025-07-22 16:03     ` Sam James
2025-07-22 21:37       ` Elijah Newren
2025-07-22 21:55         ` Sam James
2025-07-22 22:08           ` Collin Funk
2025-07-18  9:23 ` Christian Brabandt
2025-07-18 16:26   ` Junio C Hamano
2025-07-19  0:32     ` Elijah Newren
2025-07-18 13:34 ` Phillip Wood
2025-07-18 21:25   ` Eli Schwartz
2025-07-19  0:48     ` Haelwenn (lanodan) Monnier
2025-07-22 12:21       ` Patrick Steinhardt
2025-07-22 14:24     ` Patrick Steinhardt
2025-07-22 15:14       ` Eli Schwartz
2025-07-22 15:56       ` Sam James
2025-07-23  4:32         ` Patrick Steinhardt
2025-07-24  9:01           ` Pierre-Emmanuel Patry
2025-07-24 10:00             ` Patrick Steinhardt
2025-07-28  9:06               ` Pierre-Emmanuel Patry
2025-07-18 14:38 ` Junio C Hamano
2025-07-18 21:56   ` Ezekiel Newren
2025-07-21 10:14   ` Phillip Wood
2025-07-21 18:33     ` Junio C Hamano
2025-07-19 21:53 ` Johannes Schindelin
2025-07-20  8:45   ` Matthias Aßhauer
2025-08-15  1:22 ` [PATCH v2 00/17] " Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 01/17] doc: add a policy for using Rust brian m. carlson via GitGitGadget
2025-08-15 17:03     ` Matthias Aßhauer
2025-08-15 21:31       ` Junio C Hamano
2025-08-16  8:06         ` Matthias Aßhauer
2025-08-19  2:06       ` Ezekiel Newren
2025-08-15  1:22   ` [PATCH v2 02/17] xdiff: introduce rust Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 03/17] xdiff/xprepare: remove superfluous forward declarations Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 04/17] xdiff: delete unnecessary fields from xrecord_t and xdfile_t Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 05/17] xdiff: make fields of xrecord_t Rust friendly Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 06/17] xdiff: separate parsing lines from hashing them Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 07/17] xdiff: conditionally use Rust's implementation of xxhash Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 08/17] github workflows: install rust Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 09/17] Do support Windows again after requiring Rust Johannes Schindelin via GitGitGadget
2025-08-15 17:12     ` Matthias Aßhauer
2025-08-15 21:48       ` Junio C Hamano
2025-08-15 22:11         ` Johannes Schindelin
2025-08-15 23:37           ` Junio C Hamano
2025-08-15 23:37         ` Junio C Hamano
2025-08-16  8:53         ` Matthias Aßhauer
2025-08-17 15:57           ` Junio C Hamano
2025-08-19  2:22       ` Ezekiel Newren
2025-08-15  1:22   ` [PATCH v2 10/17] win+Meson: allow for xdiff to be compiled with MSVC Johannes Schindelin via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 11/17] win+Meson: do allow linking with the Rust-built xdiff Johannes Schindelin via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 12/17] github workflows: define rust versions and targets in the same place Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 13/17] github workflows: upload Cargo.lock Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 14/17] xdiff: implement a white space iterator in Rust Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 15/17] xdiff: create line_hash() and line_equal() Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 16/17] xdiff: optimize case where --ignore-cr-at-eol is the only whitespace flag Ezekiel Newren via GitGitGadget
2025-08-15  1:22   ` [PATCH v2 17/17] xdiff: use rust's version of whitespace processing Ezekiel Newren via GitGitGadget
2025-08-15 15:07   ` [-SPAM-] [PATCH v2 00/17] RFC: Accelerate xdiff and begin its rustification Ramsay Jones
2025-08-19  2:00     ` Elijah Newren
2025-08-24 16:52       ` Patrick Steinhardt
2025-08-18 22:31   ` Junio C Hamano
2025-08-18 23:52     ` Ben Knoble
2025-08-19  1:52     ` Elijah Newren
2025-08-19  9:47       ` Junio C Hamano
2025-08-23  3:55   ` [PATCH v3 00/15] RFC: Cleanup " Ezekiel Newren via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 01/15] doc: add a policy for using Rust brian m. carlson via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 02/15] xdiff: introduce rust Ezekiel Newren via GitGitGadget
2025-08-23 13:43       ` rsbecker
2025-08-23 14:26         ` Kristoffer Haugsbakk
2025-08-23 15:06           ` rsbecker
2025-08-23 18:30             ` Elijah Newren
2025-08-23 19:24               ` brian m. carlson
2025-08-23 20:04                 ` rsbecker
2025-08-23 20:36                 ` Sam James
2025-08-23 21:17                 ` Haelwenn (lanodan) Monnier
2025-08-27  1:57               ` Taylor Blau
2025-08-27 14:39                 ` rsbecker
2025-08-27 17:06                   ` Junio C Hamano
2025-08-27 17:15                     ` rsbecker
2025-08-27 20:12                     ` Taylor Blau
2025-08-27 20:22                       ` Junio C Hamano
2025-09-02 11:16                         ` Patrick Steinhardt
2025-09-02 11:30                           ` Sam James
2025-09-02 17:27                           ` brian m. carlson
2025-09-02 18:47                             ` Sam James
2025-09-03 18:22                               ` Collin Funk
2025-09-03  5:40                             ` Patrick Steinhardt
2025-09-03 16:22                               ` Ramsay Jones
2025-09-03 22:10                               ` Junio C Hamano
2025-09-03 22:48                                 ` Josh Steadmon
2025-09-04 11:10                                 ` Patrick Steinhardt
2025-09-04 15:45                                   ` Junio C Hamano
2025-09-05  8:23                                     ` Patrick Steinhardt
2025-09-04  0:57                               ` brian m. carlson
2025-09-04 11:39                                 ` Patrick Steinhardt
2025-09-04 13:53                                   ` Sam James
2025-09-05  3:55                                     ` Elijah Newren
2025-09-04 23:17                                   ` Ezekiel Newren
2025-09-05  3:54                                   ` Elijah Newren
2025-09-05  6:50                                     ` Patrick Steinhardt
2025-09-07  4:10                                       ` Elijah Newren
2025-09-07 16:09                                         ` rsbecker
2025-09-08 10:12                                           ` Phillip Wood
2025-09-08 15:32                                             ` rsbecker
2025-09-08 15:10                                           ` Ezekiel Newren
2025-09-08 15:41                                             ` rsbecker
2025-09-08 15:31                                           ` Elijah Newren
2025-09-08 15:36                                             ` rsbecker
2025-09-08 16:13                                               ` Elijah Newren
2025-09-08 17:01                                                 ` rsbecker
2025-09-08  6:40                                         ` Patrick Steinhardt
2025-09-05 10:31                                     ` Phillip Wood
2025-09-05 11:32                                       ` Sam James
2025-09-05 13:14                                       ` Phillip Wood
2025-09-05 13:23                                         ` Patrick Steinhardt
2025-09-05 15:37                                         ` Junio C Hamano
2025-09-08  6:40                                           ` Patrick Steinhardt
2025-08-23 14:29         ` Ezekiel Newren
2025-08-23  3:55     ` [PATCH v3 03/15] github workflows: install rust Ezekiel Newren via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 04/15] win+Meson: do allow linking with the Rust-built xdiff Johannes Schindelin via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 05/15] github workflows: upload Cargo.lock Ezekiel Newren via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 06/15] ivec: create a vector type that is interoperable between C and Rust Ezekiel Newren via GitGitGadget
2025-08-23  8:12       ` Kristoffer Haugsbakk
2025-08-23  9:29         ` Ezekiel Newren
2025-08-23 16:14       ` Junio C Hamano
2025-08-23 16:37         ` Ezekiel Newren
2025-08-23 18:05       ` Junio C Hamano
2025-08-23 20:29         ` Ezekiel Newren
2025-08-25 19:16         ` Elijah Newren
2025-08-26  5:40           ` Junio C Hamano
2025-08-24 13:31       ` Ben Knoble
2025-08-25 20:40         ` Ezekiel Newren
2025-08-26 13:30           ` D. Ben Knoble
2025-08-26 18:47             ` Ezekiel Newren
2025-08-26 22:01               ` brian m. carlson
2025-08-23  3:55     ` [PATCH v3 07/15] xdiff/xprepare: remove superfluous forward declarations Ezekiel Newren via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 08/15] xdiff: delete unnecessary fields from xrecord_t and xdfile_t Ezekiel Newren via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 09/15] xdiff: make fields of xrecord_t Rust friendly Ezekiel Newren via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 10/15] xdiff: use one definition for freeing xdfile_t Ezekiel Newren via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 11/15] xdiff: replace chastore with an ivec in xdfile_t Ezekiel Newren via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 12/15] xdiff: delete nrec field from xdfile_t Ezekiel Newren via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 13/15] xdiff: delete recs " Ezekiel Newren via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 14/15] xdiff: make xdfile_t more rust friendly Ezekiel Newren via GitGitGadget
2025-08-23  3:55     ` [PATCH v3 15/15] xdiff: implement xdl_trim_ends() in Rust Ezekiel Newren via GitGitGadget

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