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From: Glen Choo <chooglen@google.com>
To: Taylor Blau <me@ttaylorr.com>,
	Glen Choo via GitGitGadget <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org,
	"brian m. carlson" <sandals@crustytoothpaste.net>,
	"Derrick Stolee" <derrickstolee@github.com>,
	"Junio C Hamano" <gitster@pobox.com>,
	"Emily Shaffer" <emilyshaffer@google.com>,
	"Jonathan Tan" <jonathantanmy@google.com>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: Re: [PATCH v6 3/5] config: learn `git_protected_config()`
Date: Wed, 06 Jul 2022 15:42:46 -0700	[thread overview]
Message-ID: <kl6lczehsw0p.fsf@chooglen-macbookpro.roam.corp.google.com> (raw)
In-Reply-To: <Yr5MZhgTBFgZh/XB@nand.local>

Taylor Blau <me@ttaylorr.com> writes:

> On Thu, Jun 30, 2022 at 06:13:57PM +0000, Glen Choo via GitGitGadget wrote:
>> In light of constraint 1, this implementation can still be improved
>> since git_protected_config() iterates through every variable in
>> protected_config, which may still be too expensive. There exist constant
>> time lookup functions for non-protected configuration
>> (repo_config_get_*()), but for simplicity, this commit does not
>> implement similar functions for protected configuration.
>
> I don't quite follow along with this paragraph: it sounds like reading
> protected configuration is supposed to be as fast as possible. But you
> note that only the slower variant of reading each configuration variable
> one at a time is implemented.

Right. I should have been clearer that this implementation is "fast
enough without introducing too much noise/complexity", and not "as fast
as possible".

> If we care about speed (and I think we should here), then would it make
> more sense to implement only the lookup functions like
> repo_config_get_*() for protected context? That would encourage usage by
> providing a more limited set of options to callers.

I held off on implementing these functions because:

- It requires rewriting `safe.directory`, which reads a multivalued
  string using a config iterator. It's not onerous to do (I had a POC
  of this at some point), but it seemed pretty noisy.
- It seems too noisy to implement all of the protected_config_get_*()
  functions, and a little inconsistent to only implement the ones used
  in this series (but maybe a little inconsistency is ok?)

But maybe a little noise and inconsistency is worth the performance
improvement, especially since it's been brought up ~1.5 times before
this [1] [2]. I'll do this for sure if you feel strongly about it,
otherwise I'll just try it out just to see what I think about it.

[1] https://lore.kernel.org/git/802c3541-3301-43fc-c39e-edd44e61a4eb@github.com
[2] https://lore.kernel.org/git/xmqqbkv4t7gp.fsf@gitster.g

>> Signed-off-by: Glen Choo <chooglen@google.com>
>> ---
>>  config.c                     | 51 ++++++++++++++++++++++++++++++++++++
>>  config.h                     | 17 ++++++++++++
>>  t/t5544-pack-objects-hook.sh |  7 ++++-
>>  upload-pack.c                | 27 ++++++++++++-------
>>  4 files changed, 91 insertions(+), 11 deletions(-)
>>
>> diff --git a/config.c b/config.c
>> index 9b0e9c93285..29e62f5d0ed 100644
>> --- a/config.c
>> +++ b/config.c
>> @@ -81,6 +81,18 @@ static enum config_scope current_parsing_scope;
>>  static int pack_compression_seen;
>>  static int zlib_compression_seen;
>>
>> +/*
>> + * Config that comes from trusted sources, namely:
>
> Should we be using the word "scope" here instead of sources? I think
> it's clear enough from the context what you're referring to, but in the
> spirit of being consistent...

Good catch.

>> + * - system config files (e.g. /etc/gitconfig)
>> + * - global config files (e.g. $HOME/.gitconfig,
>> + *   $XDG_CONFIG_HOME/git)
>> + * - the command line.
>> + *
>> + * This is declared here for code cleanliness, but unlike the other
>> + * static variables, this does not hold config parser state.
>> + */
>> +static struct config_set protected_config;
>> +
>>  static int config_file_fgetc(struct config_source *conf)
>>  {
>>  	return getc_unlocked(conf->u.file);
>> @@ -2378,6 +2390,11 @@ int git_configset_add_file(struct config_set *cs, const char *filename)
>>  	return git_config_from_file(config_set_callback, filename, cs);
>>  }
>>
>> +int git_configset_add_parameters(struct config_set *cs)
>> +{
>> +	return git_config_from_parameters(config_set_callback, cs);
>> +}
>> +
>>  int git_configset_get_value(struct config_set *cs, const char *key, const char **value)
>>  {
>>  	const struct string_list *values = NULL;
>> @@ -2619,6 +2636,40 @@ int repo_config_get_pathname(struct repository *repo,
>>  	return ret;
>>  }
>>
>> +/* Read values into protected_config. */
>> +static void read_protected_config(void)
>> +{
>> +	char *xdg_config = NULL, *user_config = NULL, *system_config = NULL;
>> +
>> +	git_configset_init(&protected_config);
>> +
>> +	system_config = git_system_config();
>> +	git_global_config(&user_config, &xdg_config);
>> +
>> +	git_configset_add_file(&protected_config, system_config);
>> +	git_configset_add_file(&protected_config, xdg_config);
>> +	git_configset_add_file(&protected_config, user_config);
>> +	git_configset_add_parameters(&protected_config);
>> +
>> +	free(system_config);
>> +	free(xdg_config);
>> +	free(user_config);
>> +}
>> +
>> +/* Ensure that protected_config has been initialized. */
>> +static void git_protected_config_check_init(void)
>> +{
>> +	if (protected_config.hash_initialized)
>> +		return;
>> +	read_protected_config();
>> +}
>> +
>> +void git_protected_config(config_fn_t fn, void *data)
>> +{
>> +	git_protected_config_check_init();
>
> This may be copying from an existing pattern, but I think you could
> avoid the extra function declaration by writing git_protected_config()
> as:
>
>     if (!protected_config.hash_initialized)
>         read_protected_config();
>     configset_iter(&protected_config, fn, data);

You're right, I can drop this if I don't implement
protected_config_get_*(); this pattern only makes sense for
git_config_check_init() because it's called by multiple functions.

> Thanks,
> Taylor

  reply	other threads:[~2022-07-06 22:43 UTC|newest]

Thread overview: 113+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-06 18:30 [PATCH] [RFC] setup.c: make bare repo discovery optional Glen Choo via GitGitGadget
2022-05-06 20:33 ` Junio C Hamano
2022-05-09 21:42 ` Taylor Blau
2022-05-09 22:54   ` Junio C Hamano
2022-05-09 23:57     ` Taylor Blau
2022-05-10  0:23       ` Junio C Hamano
2022-05-10 22:00   ` Glen Choo
2022-05-13 23:37 ` [PATCH v2 0/2] " Glen Choo via GitGitGadget
2022-05-13 23:37   ` [PATCH v2 1/2] " Glen Choo via GitGitGadget
2022-05-16 18:12     ` Glen Choo
2022-05-16 18:46     ` Derrick Stolee
2022-05-16 22:25       ` Taylor Blau
2022-05-17 20:24       ` Glen Choo
2022-05-17 21:51         ` Glen Choo
2022-05-13 23:37   ` [PATCH v2 2/2] setup.c: learn discovery.bareRepository=cwd Glen Choo via GitGitGadget
2022-05-16 18:49     ` Derrick Stolee
2022-05-16 16:40   ` [PATCH v2 0/2] setup.c: make bare repo discovery optional Junio C Hamano
2022-05-16 18:36     ` Glen Choo
2022-05-16 19:16       ` Junio C Hamano
2022-05-16 20:27         ` Glen Choo
2022-05-16 22:16           ` Junio C Hamano
2022-05-16 16:43   ` Junio C Hamano
2022-05-16 19:07   ` Derrick Stolee
2022-05-16 22:43     ` Taylor Blau
2022-05-16 23:19     ` Junio C Hamano
2022-05-17 18:56     ` Glen Choo
2022-05-27 21:09   ` [PATCH v3 0/5] config: introduce discovery.bare and protected config Glen Choo via GitGitGadget
2022-05-27 21:09     ` [PATCH v3 1/5] Documentation: define protected configuration Glen Choo via GitGitGadget
2022-05-27 23:29       ` Junio C Hamano
2022-06-02 12:42         ` Derrick Stolee
2022-06-02 16:53           ` Junio C Hamano
2022-06-02 17:39             ` Glen Choo
2022-06-03 15:57         ` Glen Choo
2022-05-27 21:09     ` [PATCH v3 2/5] config: read protected config with `git_protected_config()` Glen Choo via GitGitGadget
2022-05-28  0:28       ` Junio C Hamano
2022-05-31 17:43         ` Glen Choo
2022-06-01 15:58           ` Junio C Hamano
2022-06-02 12:56       ` Derrick Stolee
2022-05-27 21:09     ` [PATCH v3 3/5] setup.c: create `discovery.bare` Glen Choo via GitGitGadget
2022-05-28  0:59       ` Junio C Hamano
2022-06-02 13:11       ` Derrick Stolee
2022-05-27 21:09     ` [PATCH v3 4/5] config: include "-c" in protected config Glen Choo via GitGitGadget
2022-06-02 13:15       ` Derrick Stolee
2022-05-27 21:09     ` [PATCH v3 5/5] upload-pack: make uploadpack.packObjectsHook protected Glen Choo via GitGitGadget
2022-06-02 13:18       ` Derrick Stolee
2022-06-07 20:57     ` [PATCH v4 0/5] config: introduce discovery.bare and protected config Glen Choo via GitGitGadget
2022-06-07 20:57       ` [PATCH v4 1/5] Documentation/git-config.txt: add SCOPES section Glen Choo via GitGitGadget
2022-06-07 20:57       ` [PATCH v4 2/5] Documentation: define protected configuration Glen Choo via GitGitGadget
2022-06-22 21:58         ` Jonathan Tan
2022-06-23 18:21           ` Glen Choo
2022-06-07 20:57       ` [PATCH v4 3/5] config: read protected config with `git_protected_config()` Glen Choo via GitGitGadget
2022-06-07 22:49         ` Junio C Hamano
2022-06-08  0:22           ` Glen Choo
2022-06-07 20:57       ` [PATCH v4 4/5] safe.directory: use git_protected_config() Glen Choo via GitGitGadget
2022-06-07 20:57       ` [PATCH v4 5/5] setup.c: create `discovery.bare` Glen Choo via GitGitGadget
2022-06-07 21:37         ` Glen Choo
2022-06-22 22:03       ` [PATCH v4 0/5] config: introduce discovery.bare and protected config Jonathan Tan
2022-06-23 17:13         ` Glen Choo
2022-06-23 18:32           ` Junio C Hamano
2022-06-27 17:34             ` Glen Choo
2022-06-27 18:19       ` Glen Choo
2022-06-27 18:36       ` [PATCH v5 " Glen Choo via GitGitGadget
2022-06-27 18:36         ` [PATCH v5 1/5] Documentation/git-config.txt: add SCOPES section Glen Choo via GitGitGadget
2022-06-27 18:36         ` [PATCH v5 2/5] Documentation: define protected configuration Glen Choo via GitGitGadget
2022-06-27 18:36         ` [PATCH v5 3/5] config: learn `git_protected_config()` Glen Choo via GitGitGadget
2022-06-27 18:36         ` [PATCH v5 4/5] safe.directory: use git_protected_config() Glen Choo via GitGitGadget
2022-06-27 18:36         ` [PATCH v5 5/5] setup.c: create `discovery.bare` Glen Choo via GitGitGadget
2022-06-30 13:20           ` Ævar Arnfjörð Bjarmason
2022-06-30 17:28             ` Glen Choo
2022-06-30 18:13         ` [PATCH v6 0/5] config: introduce discovery.bare and protected config Glen Choo via GitGitGadget
2022-06-30 18:13           ` [PATCH v6 1/5] Documentation/git-config.txt: add SCOPES section Glen Choo via GitGitGadget
2022-06-30 22:32             ` Taylor Blau
2022-07-06 17:44               ` Glen Choo
2022-06-30 18:13           ` [PATCH v6 2/5] Documentation: define protected configuration Glen Choo via GitGitGadget
2022-06-30 23:49             ` Taylor Blau
2022-07-06 18:21               ` Glen Choo
2022-06-30 18:13           ` [PATCH v6 3/5] config: learn `git_protected_config()` Glen Choo via GitGitGadget
2022-07-01  1:22             ` Taylor Blau
2022-07-06 22:42               ` Glen Choo [this message]
2022-06-30 18:13           ` [PATCH v6 4/5] safe.directory: use git_protected_config() Glen Choo via GitGitGadget
2022-06-30 18:13           ` [PATCH v6 5/5] setup.c: create `discovery.bare` Glen Choo via GitGitGadget
2022-07-01  1:30             ` Taylor Blau
2022-07-07 19:55               ` Glen Choo
2022-06-30 22:13           ` [PATCH v6 0/5] config: introduce discovery.bare and protected config Taylor Blau
2022-06-30 23:07           ` Ævar Arnfjörð Bjarmason
2022-07-01 17:37             ` Glen Choo
2022-07-08 21:58               ` Ævar Arnfjörð Bjarmason
2022-07-12 20:47                 ` Glen Choo
2022-07-12 23:53                   ` Ævar Arnfjörð Bjarmason
2022-07-07 23:01           ` [PATCH v7 " Glen Choo via GitGitGadget
2022-07-07 23:01             ` [PATCH v7 1/5] Documentation/git-config.txt: add SCOPES section Glen Choo via GitGitGadget
2022-07-07 23:43               ` Junio C Hamano
2022-07-08 17:01                 ` Glen Choo
2022-07-08 19:01                   ` Junio C Hamano
2022-07-08 21:38                     ` Glen Choo
2022-07-07 23:01             ` [PATCH v7 2/5] Documentation: define protected configuration Glen Choo via GitGitGadget
2022-07-08  0:39               ` Junio C Hamano
2022-07-07 23:01             ` [PATCH v7 3/5] config: learn `git_protected_config()` Glen Choo via GitGitGadget
2022-07-07 23:01             ` [PATCH v7 4/5] safe.directory: use git_protected_config() Glen Choo via GitGitGadget
2022-07-07 23:01             ` [PATCH v7 5/5] setup.c: create `discovery.bare` Glen Choo via GitGitGadget
2022-07-08  1:07             ` [PATCH v7 0/5] config: introduce discovery.bare and protected config Junio C Hamano
2022-07-08 20:35               ` Glen Choo
2022-07-12 22:11                 ` Glen Choo
2022-07-14 21:27             ` [PATCH v8 0/5] config: introduce safe.bareRepository " Glen Choo via GitGitGadget
2022-07-14 21:27               ` [PATCH v8 1/5] Documentation/git-config.txt: add SCOPES section Glen Choo via GitGitGadget
2022-07-14 21:27               ` [PATCH v8 2/5] Documentation: define protected configuration Glen Choo via GitGitGadget
2022-07-14 21:27               ` [PATCH v8 3/5] config: learn `git_protected_config()` Glen Choo via GitGitGadget
2022-07-25 18:26                 ` SANITIZE=address failure on master (was: [PATCH v8 3/5] config: learn `git_protected_config()`) Ævar Arnfjörð Bjarmason
2022-07-25 20:15                   ` Glen Choo
2022-07-25 20:41                     ` Ævar Arnfjörð Bjarmason
2022-07-25 20:56                       ` Glen Choo
2022-07-14 21:28               ` [PATCH v8 4/5] safe.directory: use git_protected_config() Glen Choo via GitGitGadget
2022-07-14 21:28               ` [PATCH v8 5/5] setup.c: create `safe.bareRepository` Glen Choo via GitGitGadget

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