From: Ramsay Jones <ramsay@ramsay1•demon.co.uk>
To: Junio C Hamano <gitster@pobox•com>
Cc: Tanay Abhra <tanayabh@gmail•com>,
git@vger•kernel.org, Ramkumar Ramachandra <artagnon@gmail•com>,
Matthieu Moy <Matthieu.Moy@grenoble-inp•fr>
Subject: Re: [PATCH v3 2/3] config: add hashtable for config parsing & retrieval
Date: Tue, 24 Jun 2014 16:57:31 +0100 [thread overview]
Message-ID: <53A99FEB.5040808@ramsay1.demon.co.uk> (raw)
In-Reply-To: <xmqqsimv9pjx.fsf@gitster.dls.corp.google.com>
On 24/06/14 00:25, Junio C Hamano wrote:
> Ramsay Jones <ramsay@ramsay1•demon.co.uk> writes:
>
>>> +static struct hashmap *get_config_cache(void)
>>> +{
>>> + static struct hashmap config_cache;
>>> + if (!hashmap_initialized) {
>>> + config_cache_init(&config_cache);
>>> + hashmap_initialized = 1;
>>> + git_config(config_cache_callback, NULL);
>>> + }
>>> + return &config_cache;
>>> +}
>>
>> [I have not been following this series at all (sorry I haven't had
>> the time to spare), so take these comments with a very big pinch of
>> salt! ie just ignore me if it's already been discussed etc. ;-) ]
>>
>> The 'git config' command can be used to read arbitrary files (so long
>> as they conform to the config syntax). For example, see the --file and
>> --blob options to git-config. At present, I think only scripted commands
>> use this facility (eg git-submodule). Noting the singleton config_cache,
>> what happens when git-submodule becomes a C builtin, or indeed any other
>> C builtin wants to take advantage of the new code when processing a non-
>> standard config file?
>
> Yup, that is a very good point. There needs an infrastructure to
> tie a set of files (i.e. the standard one being the chain of
> system-global /etc/gitconfig to repo-specific .git/config, and any
> custom one that can be specified by the caller like submodule code)
> to a separate hashmap; a future built-in submodule code would use
> two hashmaps aka "config-caches", one to manage the usual
> "configuration" and the other to manage the contents of the
> .gitmodules file.
>
I had expected to see one hash table per file/blob, with the three
standard config hash tables linked together to implement the scope/
priority rules. (Well, these could be merged into one, as the current
code does, since that makes handling "multi" keys slightly easier).
ie when looking up a symbol in the .git/config, if not found then
follow the link to parent scope (~/.gitconfig) and search there ...
Of course, other uses (I think) represent only a single scope, so they
would not have any parent scopes to link to.
> When we are operating across repositories (think "recursive
> checkout"), we somehow have to deal with multiple sets of
> configuration, one that applies to the top-level superproject and
> others that apply to individual submodule repositories.
>
Here, you could push the new .git/config onto a stack while linking
to the parent (~/.gitconfig) scope. So, the lookup code starts from
the stack top, etc, ...
> Even there is currently one caller, the "git config" command
> implementation, if one is designing the new API, the design
> shouldn't be tied to a singleton limitation, I would have to say, so
> that future callers do not have to throw away everything done in
> this series and start from scratch.
> .
I would like to stress that, despite the above, I have not given
any great thought to this project. So please take my comments with
a big pinch of salt. I was just scrolling through the patch in my
email client and was surprised to see the singleton ...
ATB,
Ramsay Jones
next prev parent reply other threads:[~2014-06-24 15:57 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-23 10:11 [PATCH v3 0/3] git config cache & special querying api utilizing the cache Tanay Abhra
2014-06-23 10:11 ` [PATCH v3 1/3] string-list: add string_list initialiser helper functions Tanay Abhra
2014-06-23 12:36 ` Torsten Bögershausen
2014-06-23 13:19 ` Tanay Abhra
2014-06-23 10:11 ` [PATCH v3 2/3] config: add hashtable for config parsing & retrieval Tanay Abhra
2014-06-23 11:55 ` Matthieu Moy
2014-06-24 12:06 ` Tanay Abhra
2014-06-25 20:25 ` Karsten Blees
2014-06-23 14:57 ` Ramsay Jones
2014-06-23 16:20 ` Tanay Abhra
2014-06-24 15:32 ` Ramsay Jones
2014-06-26 16:15 ` Matthieu Moy
2014-06-23 23:25 ` Junio C Hamano
2014-06-24 7:23 ` Tanay Abhra
2014-06-25 18:21 ` Junio C Hamano
2014-06-24 7:25 ` Tanay Abhra
2014-06-24 15:57 ` Ramsay Jones [this message]
2014-06-25 18:13 ` Junio C Hamano
2014-06-25 20:23 ` Karsten Blees
2014-06-25 20:53 ` Junio C Hamano
2014-06-26 17:37 ` Matthieu Moy
2014-06-26 19:00 ` Junio C Hamano
2014-06-26 19:19 ` Karsten Blees
2014-06-26 21:21 ` Junio C Hamano
2014-06-27 8:19 ` Karsten Blees
2014-06-27 8:19 ` Matthieu Moy
2014-06-27 17:13 ` Junio C Hamano
2014-06-23 23:14 ` Junio C Hamano
2014-06-24 12:21 ` Tanay Abhra
2014-06-26 16:27 ` Matthieu Moy
2014-06-25 21:44 ` Karsten Blees
2014-06-26 16:43 ` Matthieu Moy
2014-06-23 10:11 ` [PATCH v3 3/3] test-config: add usage examples for non-callback query functions Tanay Abhra
2014-06-25 11:19 ` Eric Sunshine
2014-06-26 8:40 ` Tanay Abhra
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