From: Elijah Newren <newren@gmail.com>
To: Jeff King <peff@peff.net>
Cc: Calvin Wan <calvinwan@google.com>,
Elijah Newren via GitGitGadget <gitgitgadget@gmail.com>,
git@vger.kernel.org
Subject: Re: [PATCH 23/24] hash-ll, hashmap: move oidhash() to hash-ll
Date: Thu, 11 May 2023 19:08:00 -0700 [thread overview]
Message-ID: <CABPp-BEVWS2atggSNC16bQ3FxvNxU-76+o3B5QF+2opiwOLfgQ@mail.gmail.com> (raw)
In-Reply-To: <20230511183143.GA1978320@coredump.intra.peff.net>
On Thu, May 11, 2023 at 11:31 AM Jeff King <peff@peff.net> wrote:
>
> On Thu, May 11, 2023 at 05:24:01PM +0000, Calvin Wan wrote:
>
> > > Note that there's a small but
> > > important change to khash.h in this patch as well to allow this move,
> > > which is easy to overlook.
> >
> > Can you go into a bit more detail as to how this change allows the move?
> > (An example of the concatenation would probably be sufficient)
>
> Even after finding the hunk, I have to admit I scratched my head at what
> was going on.
>
> The answer is that object-store-ll.h now uses "struct kh_odb_path_map"
> instead of a typedef'd kh_odb_path_map. Using the typedef is the way
> that the khash library intends to work (and the only way it provides),
> but does not match our usual Git style. In other users of the khash
> library, we just bend to their will and use the typedef typedef (which
> we have to, because it does not even name the struct type directly!).
>
> But we can't do that here, because object-store-ll.h does not include
> khash.h, so must forward declare the struct (actually, we do not even do
> that, but it is legal to just refer to it as a pointer). But the
> compiler only understands what we are doing if the "struct" keyword is
> present.
>
> So I think the solution here is reasonable, but I actually think it
> would make sense to pull it out into its own patch, with a rationale
> like:
>
> khash.h lets you instantiate custom hash types that map between two
> types. These are defined as a struct, as you might expect, and khash
> typedef's that to kh_foo_t. But it declares the struct anonymously,
> which doesn't give a name to the struct type itself; there is no
> "struct kh_foo". This has two small downsides:
>
> - when using khash, we declare "kh_foo_t *the_foo". This is
> unlike our usual naming style, which is "struct kh_foo *the_foo".
>
> - you can't forward-declare a typedef of an unnamed struct type in
> C. So we might do something like this in a header file:
>
> struct kh_foo;
> struct bar {
> struct kh_foo *the_foo;
> };
>
> to avoid having to include the header that defines the real
> kh_foo. But that doesn't work with the typedef'd name. Without the
> "struct" keyword, the compiler doesn't know we mean that kh_foo is
> a type.
>
> So let's always give khash structs the name that matches our
> conventions ("struct kh_foo" to match "kh_foo_t"). We'll keep doing
> the typedef to retain compatibility with existing callers.
>
> The "you can't do this in C" is all off the top of my head. I think it's
> correct, but there may be a clever way to do it that I don't know of.
> Though even there is, I think "make khash more like our usual
> conventions" is a good thing by itself.
Oh, wow, I was about to type up an explanation to Calvin, but you did
so in even greater detail. Sweet.
And sure, I'd be happy to split this out into a separate patch and
steal the commit message. I think you deserve Co-author, though,
given it's only a 1-line code change versus the 20 line commit message
you wrote...
next prev parent reply other threads:[~2023-05-12 2:09 UTC|newest]
Thread overview: 115+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-07 3:45 [PATCH 00/24] Header cleanups (final splitting of cache.h, and some splitting of other headers) Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 01/24] init-db: remove unnecessary global variable & document existing bug Elijah Newren via GitGitGadget
2023-05-11 17:24 ` Calvin Wan
2023-05-12 1:55 ` Elijah Newren
2023-05-11 20:43 ` Glen Choo
2023-05-12 1:21 ` Elijah Newren
2023-05-12 17:26 ` Glen Choo
2023-05-07 3:45 ` [PATCH 02/24] init-db, clone: change unnecessary global into passed parameter Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 03/24] setup: adopt shared init-db & clone code Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 04/24] read-cache: move shared commit and ls-files code Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 05/24] add: modify add_files_to_cache() to avoid globals Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 06/24] read-cache: move shared add/checkout/commit code Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 07/24] statinfo: move stat_{data,validity} functions from cache/read-cache Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 08/24] run-command.h: move declarations for run-command.c from cache.h Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 09/24] name-hash.h: move declarations for name-hash.c " Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 10/24] sparse-index.h: move declarations for sparse-index.c " Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 11/24] preload-index.h: move declarations for preload-index.c from elsewhere Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 12/24] diff.h: move declaration for global in diff.c from cache.h Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 13/24] merge.h: move declarations for merge.c " Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 14/24] repository.h: move declaration of the_index " Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 15/24] read-cache*.h: move declarations for read-cache.c functions " Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 16/24] cache.h: remove this no-longer-used header Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 17/24] log-tree: replace include of revision.h with simple forward declaration Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 18/24] repository: remove unnecessary include of path.h Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 19/24] diff.h: remove unnecessary include of oidset.h Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 20/24] list-objects-filter-options.h: remove unneccessary include Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 21/24] builtin.h: remove unneccessary includes Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 22/24] git-compat-util.h: remove unneccessary include of wildmatch.h Elijah Newren via GitGitGadget
2023-05-07 3:45 ` [PATCH 23/24] hash-ll, hashmap: move oidhash() to hash-ll Elijah Newren via GitGitGadget
2023-05-11 17:24 ` Calvin Wan
2023-05-11 18:31 ` Jeff King
2023-05-11 18:39 ` Felipe Contreras
2023-05-12 2:08 ` Elijah Newren [this message]
2023-05-12 4:07 ` Jeff King
2023-05-07 3:45 ` [PATCH 24/24] fsmonitor-ll.h: split this header out of fsmonitor.h Elijah Newren via GitGitGadget
2023-05-08 15:29 ` [PATCH 00/24] Header cleanups (final splitting of cache.h, and some splitting of other headers) Junio C Hamano
2023-05-09 1:31 ` Elijah Newren
2023-05-09 16:03 ` Junio C Hamano
2023-05-08 15:55 ` Junio C Hamano
2023-05-11 17:41 ` Calvin Wan
2023-05-12 6:58 ` Elijah Newren
2023-05-12 7:04 ` [PATCH v2 00/27] " Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 01/27] init-db: document existing bug with core.bare in template config Elijah Newren via GitGitGadget
2023-05-12 21:34 ` Jonathan Tan
2023-05-16 3:08 ` Elijah Newren
2023-05-12 7:04 ` [PATCH v2 02/27] init-db: remove unnecessary global variable Elijah Newren via GitGitGadget
2023-05-12 20:20 ` Glen Choo
2023-05-12 7:04 ` [PATCH v2 03/27] init-db, clone: change unnecessary global into passed parameter Elijah Newren via GitGitGadget
2023-05-12 21:28 ` Jonathan Tan
2023-05-16 2:57 ` Elijah Newren
2023-05-12 7:04 ` [PATCH v2 04/27] setup: adopt shared init-db & clone code Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 05/27] read-cache: move shared commit and ls-files code Elijah Newren via GitGitGadget
2023-05-12 21:25 ` Jonathan Tan
2023-05-12 7:04 ` [PATCH v2 06/27] add: modify add_files_to_cache() to avoid globals Elijah Newren via GitGitGadget
2023-05-15 21:44 ` Jonathan Tan
2023-05-12 7:04 ` [PATCH v2 07/27] read-cache: move shared add/checkout/commit code Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 08/27] statinfo: move stat_{data,validity} functions from cache/read-cache Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 09/27] run-command.h: move declarations for run-command.c from cache.h Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 10/27] name-hash.h: move declarations for name-hash.c " Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 11/27] sparse-index.h: move declarations for sparse-index.c " Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 12/27] preload-index.h: move declarations for preload-index.c from elsewhere Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 13/27] diff.h: move declaration for global in diff.c from cache.h Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 14/27] merge.h: move declarations for merge.c " Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 15/27] repository.h: move declaration of the_index " Elijah Newren via GitGitGadget
2023-05-15 21:50 ` Jonathan Tan
2023-05-12 7:04 ` [PATCH v2 16/27] read-cache*.h: move declarations for read-cache.c functions " Elijah Newren via GitGitGadget
2023-05-16 0:00 ` Jonathan Tan
2023-05-12 7:04 ` [PATCH v2 17/27] cache.h: remove this no-longer-used header Elijah Newren via GitGitGadget
2023-05-16 0:02 ` Jonathan Tan
2023-05-16 3:02 ` Elijah Newren
2023-05-12 7:04 ` [PATCH v2 18/27] log-tree: replace include of revision.h with simple forward declaration Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 19/27] repository: remove unnecessary include of path.h Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 20/27] diff.h: remove unnecessary include of oidset.h Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 21/27] list-objects-filter-options.h: remove unneccessary include Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 22/27] builtin.h: remove unneccessary includes Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 23/27] git-compat-util.h: remove unneccessary include of wildmatch.h Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 24/27] merge-ll: rename from ll-merge Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 25/27] khash: name the structs that khash declares Elijah Newren via GitGitGadget
2023-05-12 7:04 ` [PATCH v2 26/27] hash-ll, hashmap: move oidhash() to hash-ll Elijah Newren via GitGitGadget
2023-05-16 0:16 ` Jonathan Tan
2023-05-16 3:06 ` Elijah Newren
2023-05-12 7:04 ` [PATCH v2 27/27] fsmonitor-ll.h: split this header out of fsmonitor.h Elijah Newren via GitGitGadget
2023-05-16 0:17 ` Jonathan Tan
2023-05-16 3:07 ` Elijah Newren
2023-05-16 6:33 ` [PATCH v3 00/28] Header cleanups (final splitting of cache.h, and some splitting of other headers) Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 01/28] init-db: document existing bug with core.bare in template config Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 02/28] init-db: remove unnecessary global variable Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 03/28] init-db, clone: change unnecessary global into passed parameter Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 04/28] setup: adopt shared init-db & clone code Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 05/28] read-cache: move shared commit and ls-files code Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 06/28] add: modify add_files_to_cache() to avoid globals Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 07/28] read-cache: move shared add/checkout/commit code Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 08/28] statinfo: move stat_{data,validity} functions from cache/read-cache Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 09/28] run-command.h: move declarations for run-command.c from cache.h Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 10/28] name-hash.h: move declarations for name-hash.c " Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 11/28] sparse-index.h: move declarations for sparse-index.c " Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 12/28] preload-index.h: move declarations for preload-index.c from elsewhere Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 13/28] diff.h: move declaration for global in diff.c from cache.h Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 14/28] merge.h: move declarations for merge.c " Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 15/28] repository.h: move declaration of the_index " Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 16/28] read-cache*.h: move declarations for read-cache.c functions " Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 17/28] cache.h: remove this no-longer-used header Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 18/28] log-tree: replace include of revision.h with simple forward declaration Elijah Newren via GitGitGadget
2023-05-16 6:33 ` [PATCH v3 19/28] repository: remove unnecessary include of path.h Elijah Newren via GitGitGadget
2023-05-16 6:34 ` [PATCH v3 20/28] diff.h: remove unnecessary include of oidset.h Elijah Newren via GitGitGadget
2023-05-16 6:34 ` [PATCH v3 21/28] list-objects-filter-options.h: remove unneccessary include Elijah Newren via GitGitGadget
2023-05-16 6:34 ` [PATCH v3 22/28] builtin.h: remove unneccessary includes Elijah Newren via GitGitGadget
2023-05-16 6:34 ` [PATCH v3 23/28] git-compat-util.h: remove unneccessary include of wildmatch.h Elijah Newren via GitGitGadget
2023-05-16 6:34 ` [PATCH v3 24/28] merge-ll: rename from ll-merge Elijah Newren via GitGitGadget
2023-05-16 6:34 ` [PATCH v3 25/28] khash: name the structs that khash declares Elijah Newren via GitGitGadget
2023-05-16 6:34 ` [PATCH v3 26/28] object-store-ll.h: split this header out of object-store.h Elijah Newren via GitGitGadget
2023-05-16 6:34 ` [PATCH v3 27/28] hash-ll, hashmap: move oidhash() to hash-ll Elijah Newren via GitGitGadget
2023-05-16 6:34 ` [PATCH v3 28/28] fsmonitor-ll.h: split this header out of fsmonitor.h Elijah Newren via GitGitGadget
2023-05-23 19:49 ` [PATCH v3 00/28] Header cleanups (final splitting of cache.h, and some splitting of other headers) Calvin Wan
2023-05-24 0:11 ` Elijah Newren
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CABPp-BEVWS2atggSNC16bQ3FxvNxU-76+o3B5QF+2opiwOLfgQ@mail.gmail.com \
--to=newren@gmail.com \
--cc=calvinwan@google.com \
--cc=git@vger.kernel.org \
--cc=gitgitgadget@gmail.com \
--cc=peff@peff.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).