From: Eric Sunshine <sunshine@sunshineco.com>
To: "Eric W. Biederman" <ebiederm@gmail.com>
Cc: Junio C Hamano <gitster@pobox.com>,
git@vger.kernel.org,
"brian m. carlson" <sandals@crustytoothpaste.net>,
"Eric W . Biederman" <ebiederm@xmission.com>
Subject: Re: [PATCH 05/30] loose: add a mapping between SHA-1 and SHA-256 for loose objects
Date: Sun, 1 Oct 2023 22:36:31 -0400 [thread overview]
Message-ID: <CAPig+cS2TVZJQmfQNQud5dRcROFN3kTeu-OBTmCW=7aNjoJGxw@mail.gmail.com> (raw)
In-Reply-To: <87v8bp93j5.fsf@gmail.froward.int.ebiederm.org>
On Sun, Oct 1, 2023 at 10:11 PM Eric W. Biederman <ebiederm@gmail.com> wrote:
> Eric Sunshine <sunshine@sunshineco.com> writes:
> > On Wed, Sep 27, 2023 at 3:56 PM Eric W. Biederman <ebiederm@gmail.com> wrote:
> >> + for (; iter != kh_end(map); iter++) {
> >> + if (kh_exist(map, iter)) {
> >> + if (oideq(&kh_key(map, iter), the_hash_algo->empty_tree) ||
> >> + oideq(&kh_key(map, iter), the_hash_algo->empty_blob))
> >> + continue;
> >> + strbuf_addf(&buf, "%s %s\n", oid_to_hex(&kh_key(map, iter)), oid_to_hex(kh_value(map, iter)));
> >> + if (write_in_full(fd, buf.buf, buf.len) < 0)
> >> + goto errout;
> >> + strbuf_reset(&buf);
> >> + }
> >> + }
> >
> > Nit: If you call strbuf_reset() immediately before strbuf_addf(), then
> > you save the reader of the code the effort of having to scan backward
> > through the function to verify that `buf` is empty the first time
> > through the loop.
>
> I am actually perplexed why the code works this way.
>
> My gut says we should create the entire buffer in memory and then
> write it to disk all in a single system call, and not perform
> this line buffering.
I think I had a similar question/thought while reading the patch but...
> Doing that would remove the need for the strbuf_reset entirely,
> and would just require the buffer to be primed with the
> loose_object_header.
>
> But what is there works and I will leave it for now.
... came to this same conclusion.
> It isn't a bug, and it can be improved with a follow up patch.
Exactly.
I haven't thought through the consequences, but perhaps brian was
worried about the memory footprint of buffering the whole thing before
writing to disk.
next prev parent reply other threads:[~2023-10-02 2:36 UTC|newest]
Thread overview: 104+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-27 19:49 [PATCH 00/30] Initial support for multiple hash functions Eric W. Biederman
2023-09-27 19:55 ` [PATCH 01/30] object-file-convert: Stubs for converting from one object format to another Eric W. Biederman
2023-09-27 20:42 ` Eric Sunshine
2023-10-02 1:22 ` Eric W. Biederman
2023-10-02 2:27 ` Eric Sunshine
2023-09-27 19:55 ` [PATCH 02/30] oid-array: Teach oid-array to handle multiple kinds of oids Eric W. Biederman
2023-09-27 23:20 ` Eric Sunshine
2023-09-27 19:55 ` [PATCH 03/30] object-names: Support input of oids in any supported hash Eric W. Biederman
2023-09-27 23:29 ` Eric Sunshine
2023-10-02 1:54 ` Eric W. Biederman
2023-09-27 19:55 ` [PATCH 04/30] repository: add a compatibility hash algorithm Eric W. Biederman
2023-09-27 19:55 ` [PATCH 05/30] loose: add a mapping between SHA-1 and SHA-256 for loose objects Eric W. Biederman
2023-09-28 7:14 ` Eric Sunshine
2023-10-02 2:11 ` Eric W. Biederman
2023-10-02 2:36 ` Eric Sunshine [this message]
2023-09-27 19:55 ` [PATCH 06/30] loose: Compatibilty short name support Eric W. Biederman
2023-09-27 19:55 ` [PATCH 07/30] object-file: Update the loose object map when writing loose objects Eric W. Biederman
2023-09-27 19:55 ` [PATCH 08/30] object-file: Add a compat_oid_in parameter to write_object_file_flags Eric W. Biederman
2023-09-27 19:55 ` [PATCH 09/30] commit: write commits for both hashes Eric W. Biederman
2023-09-27 19:55 ` [PATCH 10/30] commit: Convert mergetag before computing the signature of a commit Eric W. Biederman
2023-09-27 19:55 ` [PATCH 11/30] commit: Export add_header_signature to support handling signatures on tags Eric W. Biederman
2023-09-27 19:55 ` [PATCH 12/30] tag: sign both hashes Eric W. Biederman
2023-09-27 19:55 ` [PATCH 13/30] cache: add a function to read an OID of a specific algorithm Eric W. Biederman
2023-09-27 19:55 ` [PATCH 14/30] object: Factor out parse_mode out of fast-import and tree-walk into in object.h Eric W. Biederman
2023-09-27 19:55 ` [PATCH 15/30] object-file-convert: add a function to convert trees between algorithms Eric W. Biederman
2023-09-27 19:55 ` [PATCH 16/30] object-file-convert: convert tag objects when writing Eric W. Biederman
2023-09-27 19:55 ` [PATCH 17/30] object-file-convert: Don't leak when converting tag objects Eric W. Biederman
2023-09-27 19:55 ` [PATCH 18/30] object-file-convert: convert commit objects when writing Eric W. Biederman
2023-09-27 19:55 ` [PATCH 19/30] object-file-convert: Convert commits that embed signed tags Eric W. Biederman
2023-09-27 19:55 ` [PATCH 20/30] object-file: Update object_info_extended to reencode objects Eric W. Biederman
2023-09-27 19:55 ` [PATCH 21/30] repository: Implement extensions.compatObjectFormat Eric W. Biederman
2023-09-27 21:39 ` Junio C Hamano
2023-09-28 20:18 ` Junio C Hamano
2023-09-29 0:50 ` Eric Biederman
2023-09-29 16:59 ` Eric W. Biederman
2023-09-29 18:48 ` Junio C Hamano
2023-10-02 0:48 ` Eric W. Biederman
2023-10-02 1:31 ` Eric W. Biederman
2023-09-27 19:55 ` [PATCH 22/30] rev-parse: Add an --output-object-format parameter Eric W. Biederman
2023-09-27 19:55 ` [PATCH 23/30] builtin/cat-file: Let the oid determine the output algorithm Eric W. Biederman
2023-09-27 19:55 ` [PATCH 24/30] tree-walk: init_tree_desc take an oid to get the hash algorithm Eric W. Biederman
2023-09-27 19:55 ` [PATCH 25/30] object-file: Handle compat objects in check_object_signature Eric W. Biederman
2023-09-27 19:55 ` [PATCH 26/30] builtin/ls-tree: Let the oid determine the output algorithm Eric W. Biederman
2023-09-27 19:55 ` [PATCH 27/30] test-lib: Compute the compatibility hash so tests may use it Eric W. Biederman
2023-09-27 19:55 ` [PATCH 28/30] t1006: Rename sha1 to oid Eric W. Biederman
2023-09-27 19:55 ` [PATCH 29/30] t1006: Test oid compatibility with cat-file Eric W. Biederman
2023-09-27 19:55 ` [PATCH 30/30] t1016-compatObjectFormat: Add tests to verify the conversion between objects Eric W. Biederman
2023-09-27 21:31 ` [PATCH 00/30] Initial support for multiple hash functions Junio C Hamano
2023-10-02 2:39 ` [PATCH v2 00/30] initial " Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 01/30] object-file-convert: stubs for converting from one object format to another Eric W. Biederman
2024-02-08 8:23 ` Linus Arver
2024-02-15 11:21 ` Patrick Steinhardt
2023-10-02 2:40 ` [PATCH v2 02/30] oid-array: teach oid-array to handle multiple kinds of oids Eric W. Biederman
2024-02-13 8:16 ` Linus Arver
2024-02-15 6:22 ` Eric W. Biederman
2024-02-16 0:16 ` Linus Arver
2024-02-16 4:48 ` Eric W. Biederman
2024-02-17 1:59 ` Linus Arver
2024-02-13 8:31 ` Kristoffer Haugsbakk
2024-02-15 6:24 ` Eric W. Biederman
2024-02-15 11:21 ` Patrick Steinhardt
2023-10-02 2:40 ` [PATCH v2 03/30] object-names: support input of oids in any supported hash Eric W. Biederman
2024-02-13 9:33 ` Linus Arver
2024-02-15 11:21 ` Patrick Steinhardt
2023-10-02 2:40 ` [PATCH v2 04/30] repository: add a compatibility hash algorithm Eric W. Biederman
2024-02-13 10:02 ` Linus Arver
2024-02-15 11:22 ` Patrick Steinhardt
2023-10-02 2:40 ` [PATCH v2 05/30] loose: add a mapping between SHA-1 and SHA-256 for loose objects Eric W. Biederman
2024-02-14 7:20 ` Linus Arver
2024-02-15 5:33 ` Eric W. Biederman
2024-02-15 11:22 ` Patrick Steinhardt
2023-10-02 2:40 ` [PATCH v2 06/30] loose: compatibilty short name support Eric W. Biederman
2024-02-15 11:22 ` Patrick Steinhardt
2023-10-02 2:40 ` [PATCH v2 07/30] object-file: update the loose object map when writing loose objects Eric W. Biederman
2024-02-15 11:22 ` Patrick Steinhardt
2023-10-02 2:40 ` [PATCH v2 08/30] object-file: add a compat_oid_in parameter to write_object_file_flags Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 09/30] commit: write commits for both hashes Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 10/30] commit: convert mergetag before computing the signature of a commit Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 11/30] commit: export add_header_signature to support handling signatures on tags Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 12/30] tag: sign both hashes Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 13/30] cache: add a function to read an OID of a specific algorithm Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 14/30] object: factor out parse_mode out of fast-import and tree-walk into in object.h Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 15/30] object-file-convert: add a function to convert trees between algorithms Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 16/30] object-file-convert: convert tag objects when writing Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 17/30] object-file-convert: don't leak when converting tag objects Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 18/30] object-file-convert: convert commit objects when writing Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 19/30] object-file-convert: convert commits that embed signed tags Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 20/30] object-file: update object_info_extended to reencode objects Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 21/30] repository: implement extensions.compatObjectFormat Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 22/30] rev-parse: add an --output-object-format parameter Eric W. Biederman
2024-02-08 16:25 ` Jean-Noël Avila
2023-10-02 2:40 ` [PATCH v2 23/30] builtin/cat-file: let the oid determine the output algorithm Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 24/30] tree-walk: init_tree_desc take an oid to get the hash algorithm Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 25/30] object-file: handle compat objects in check_object_signature Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 26/30] builtin/ls-tree: let the oid determine the output algorithm Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 27/30] test-lib: compute the compatibility hash so tests may use it Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 28/30] t1006: rename sha1 to oid Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 29/30] t1006: test oid compatibility with cat-file Eric W. Biederman
2023-10-02 2:40 ` [PATCH v2 30/30] t1016-compatObjectFormat: add tests to verify the conversion between objects Eric W. Biederman
2024-02-07 22:18 ` [PATCH v2 00/30] initial support for multiple hash functions Junio C Hamano
2024-02-08 0:24 ` Linus Arver
2024-02-08 6:11 ` Patrick Steinhardt
2024-02-14 7:36 ` Linus Arver
2024-02-15 11:27 ` Patrick Steinhardt
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