From: Paul Tan <pyokagan@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Git List <git@vger.kernel.org>,
Stefan Beller <sbeller@google.com>,
Johannes Schindelin <johannes.schindelin@gmx.de>,
Stephen Robin <stephen.robin@gmail.com>
Subject: Re: [PATCH v2 11/19] pull: check if in unresolved merge state
Date: Sun, 14 Jun 2015 15:44:59 +0800 [thread overview]
Message-ID: <CACRoPnTVXCGs6gwYxPLZfD-jK3qfjVzXhNSArsO-JA+a406SHg@mail.gmail.com> (raw)
In-Reply-To: <xmqq381zmqon.fsf@gitster.dls.corp.google.com>
On Thu, Jun 11, 2015 at 1:14 AM, Junio C Hamano <gitster@pobox.com> wrote:
> I (or at least some part of me) actually view git_config_get_*() as
> "if you are only going to peek a few variables, you do not have to
> do the looping yourself" convenience, which leads me (or at least
> that part of me) to say "if you are doing the looping anyway, you
> may be better off picking up the variables you care about yourself
> in that loop".
Not just a convenience, but I personally find that callback functions
usually leads to code that is harder to understand because of the use
of static/global variables to preserve state and the fact that it is
harder to break it up into smaller functions to reason about. This is
just a matter of taste though, so I don't have strong feelings about
it.
Besides, there is a greater technical reason why we should not use
git_config(): It essentially performs a linear search[1], while the
git_config_get_*() functions do a constant-time lookup. Ideally, we
should remove uses of git_config() for users that have no need to
iterate over all the configuration entries.
[1] Since we do a strcmp() for every supported config setting, for
every config entry.
I should emphasize that the call to git_config(git_default_config,
NULL) is just a workaround to load the advice.* settings. In fact,
git_default_config() only peeks at a few config settings anyway, and
can be re-written to not iterate over all the user's config entries.
As such, I don't see why the builtin/pull.c code should be written to
support the git_config() way of doing things, even if we have to use
the workaround of calling git_config(). It's like saying: we have a
bad solution, now let's make it worse ;-)
> By calling git_config() before calling any git_config_get_*()
> functions, you would be priming the cache layer with the entire
> contents of the configuration files anyway, so later calls to
> git_config_get_*() will read from that cache, so there is no
> performance penalty in mixing the two methods to access
> configuration data. That is why I felt less certain that the
> suggestion to stick to one method (instead of mixing the two) is a
> good thing to do (hence "less certain 'might'").
Right, although I think that the performance penalty due to using
git_config() is greater, and switching all the git_config_get_*()
calls to use it would just make it worse.
By the way, I got the idea that git development was moving towards
replacing use of git_config() from 5801d3b (builtin/gc.c: replace
`git_config()` with `git_config_get_*()` family, 2014-08-07).
Thanks,
Paul
next prev parent reply other threads:[~2015-06-14 7:45 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-03 6:48 [PATCH v2 00/19] Make git-pull a builtin Paul Tan
2015-06-03 6:48 ` [PATCH v2 01/19] parse-options-cb: implement parse_opt_pass_strbuf() Paul Tan
2015-06-09 23:11 ` Junio C Hamano
2015-06-03 6:48 ` [PATCH v2 02/19] parse-options-cb: implement parse_opt_pass_argv_array() Paul Tan
2015-06-03 16:56 ` Stefan Beller
2015-06-09 23:16 ` Junio C Hamano
2015-06-10 7:11 ` Paul Tan
2015-06-10 8:03 ` Junio C Hamano
2015-06-03 6:48 ` [PATCH v2 03/19] argv-array: implement argv_array_pushv() Paul Tan
2015-06-03 6:48 ` [PATCH v2 04/19] pull: implement skeletal builtin pull Paul Tan
2015-06-10 0:23 ` Junio C Hamano
2015-06-03 6:48 ` [PATCH v2 05/19] pull: implement fetch + merge Paul Tan
2015-06-09 23:27 ` Junio C Hamano
2015-06-03 6:48 ` [PATCH v2 06/19] pull: pass verbosity, --progress flags to fetch and merge Paul Tan
2015-06-09 23:36 ` Junio C Hamano
2015-06-03 6:48 ` [PATCH v2 07/19] pull: pass git-merge's options to git-merge Paul Tan
2015-06-03 6:48 ` [PATCH v2 08/19] pull: pass git-fetch's options to git-fetch Paul Tan
2015-06-03 17:16 ` Stefan Beller
2015-06-03 6:48 ` [PATCH v2 09/19] pull: error on no merge candidates Paul Tan
2015-06-09 23:56 ` Junio C Hamano
2015-06-13 5:52 ` Paul Tan
2015-06-03 6:48 ` [PATCH v2 10/19] pull: support pull.ff config Paul Tan
2015-06-09 23:59 ` Junio C Hamano
2015-06-03 6:48 ` [PATCH v2 11/19] pull: check if in unresolved merge state Paul Tan
2015-06-10 1:29 ` Junio C Hamano
2015-06-10 14:38 ` Junio C Hamano
2015-06-10 15:12 ` Paul Tan
2015-06-10 17:14 ` Junio C Hamano
2015-06-14 7:44 ` Paul Tan [this message]
2015-06-03 6:48 ` [PATCH v2 12/19] pull: fast-forward working tree if head is updated Paul Tan
2015-06-03 6:48 ` [PATCH v2 13/19] pull: implement pulling into an unborn branch Paul Tan
2015-06-10 1:31 ` Junio C Hamano
2015-06-03 6:48 ` [PATCH v2 14/19] pull: set reflog message Paul Tan
2015-06-03 6:48 ` [PATCH v2 15/19] pull: teach git pull about --rebase Paul Tan
2015-06-10 1:56 ` Junio C Hamano
2015-06-10 7:55 ` Paul Tan
2015-06-10 14:44 ` Junio C Hamano
2015-06-10 15:35 ` Paul Tan
2015-06-10 16:13 ` Junio C Hamano
2015-06-10 23:02 ` Junio C Hamano
2015-06-03 6:49 ` [PATCH v2 16/19] pull: configure --rebase via branch.<name>.rebase or pull.rebase Paul Tan
2015-06-03 6:49 ` [PATCH v2 17/19] pull --rebase: exit early when the working directory is dirty Paul Tan
2015-06-03 10:27 ` Kevin Daudt
2015-06-10 5:53 ` Kevin Daudt
2015-06-03 6:49 ` [PATCH v2 18/19] pull --rebase: error on no merge candidate cases Paul Tan
2015-06-03 17:38 ` Stefan Beller
2015-06-03 6:49 ` [PATCH v2 19/19] pull: remove redirection to git-pull.sh Paul Tan
2015-06-03 17:49 ` Stefan Beller
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