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From: Jeff Hostetler <git@jeffhostetler.com>
To: "Johannes Schindelin" <Johannes.Schindelin@gmx.de>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: Jeff Hostetler via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org, jeffhost@microsoft.com,
	Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH v6 00/15] Trace2 tracing facility
Date: Fri, 22 Mar 2019 10:01:56 -0400	[thread overview]
Message-ID: <37cffd65-58bd-3fae-a4f1-44038ed52f60@jeffhostetler.com> (raw)
In-Reply-To: <nycvar.QRO.7.76.6.1903221416230.41@tvgsbejvaqbjf.bet>



On 3/22/2019 9:17 AM, Johannes Schindelin wrote:
> Hi Ævar,
> 
> On Thu, 21 Mar 2019, Ævar Arnfjörð Bjarmason wrote:
> 
>> On Thu, Mar 21 2019, Johannes Schindelin wrote:
>>
>>> On Sun, 17 Mar 2019, Ævar Arnfjörð Bjarmason wrote:
>>>
>>>>
>>>> On Fri, Feb 15 2019, Jeff Hostetler wrote:
>>>>
>>>>> I could see having a "~/.git_tr2_config" or something similar in
>>>>> some place like "/etc" that only contained the Trace2 settings. It
>>>>> would be safe to read very early inside main() and we would not
>>>>> consider it to be part of the real config.  For example, "git
>>>>> config" would not know about it.  Then you could enforce a
>>>>> system-wide setting without any of the env var issues.
>>>>
>>>> I haven't written a patch for this, but it seems to me that we could
>>>> just start reading /etc/gitconfig via some custom config callback
>>>> code early as e.g. 58b284a2e91 ("worktree: add per-worktree config
>>>> files", 2018-10-21) does for the worktree config.
>>>
>>> Oy. Oy, oy, oy.
>>>
>>> Maybe use `read_early_config()` instead? That would be *a lot*
>>> cleaner. You could maybe use a9bcf6586d1a (alias: use the early config
>>> machinery to expand aliases, 2017-06-14) as an inspiration.
>>
>> Thanks. I was thinking *only* to do /etc/gitconfig and not the whole
>> .git/config -> ~/.gitconfig etc. sequence just in terms of saving
>> critical time (this is the performance trace path, after all...).
>>
>> But on a second reading I see that read_early_config() can do that if
>> you set config_source->file, opts->respect_includes etc. I.e. it just
>> (depending on options) resolves to git_config_from_file() which
>> 58b284a2e91 used directly.
> 
> Sure, it can exclude the repo and user config, but would that not be
> rather confusing?

This was hidden in my earlier message.

There's a lot a config machinery here with lots of chicken-n-egg
problems.  I want to know at the top of main() as quickly as possible
whether trace2 should be enabled.

I don't want to slow down git by spinning up a bunch of trace2 state
and wait until the git-dir is discovered, the "-c" args are processed,
and we dispatch into the builtin layer and the config is enumerated
to know if it should really be on or not.

I also didn't want to introduce another full iteration of the full
config system for startup performance reasons.

I played with read_early_config() at one point and it always seemed
to introduce side-effects.  Perhaps I was calling it earlier than it
was expecting and that triggered some of the git-dir discovery or
something. I don't remember all the details, I just remember that it
changed some behaviors in subtle ways.

Perhaps I could call something like git_config_from_file() with the
right set of magic bits to get it to parse exactly 1 system config
file that would contain my trace2 settings.  Hopefully, this will
not have any side-effects.

But if we lump them in with the main /etc/gitconfig settings, we
would have to explain that these trace2 config settings are
system-only and ARE NOT overridden by "-c", global, local, ...
config settings.  This would get confusing if the user tried to
set local values and did:
	git config --list --show-origin
and it showed system and local values but yet "stubbornly" refused
to use the local values over the system values. (I think this was
Johannes' point.)

That's why I was suggesting a system trace2 config file that is a
peer of /etc/gitconfig (maybe /etc/gittrace2) that would have these
values and not be expected to interact with the main config system.
That is, we just use the git_config_ routines to parse the file format,
rather than inventing another file format, but not change the
expectation of the established config value inheritance system.

If there's no objections, I'll take a look at doing this.

Thanks
Jeff



  reply	other threads:[~2019-03-22 14:01 UTC|newest]

Thread overview: 154+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-22 21:22 [PATCH 00/14] Trace2 tracing facility Jeff Hostetler via GitGitGadget
2019-01-22 21:22 ` [PATCH 01/14] trace2: Documentation/technical/api-trace2.txt Jeff Hostetler via GitGitGadget
2019-01-23 20:51   ` Junio C Hamano
2019-01-25 21:13     ` Jeff Hostetler
2019-01-25 13:19   ` SZEDER Gábor
2019-01-25 17:53     ` Josh Steadmon
2019-01-22 21:22 ` [PATCH 02/14] trace2: create new combined trace facility Jeff Hostetler via GitGitGadget
2019-01-25 11:22   ` SZEDER Gábor
2019-01-25 19:13     ` Junio C Hamano
2019-01-22 21:22 ` [PATCH 03/14] trace2: collect platform-specific process information Jeff Hostetler via GitGitGadget
2019-01-22 21:22 ` [PATCH 04/14] trace2:data: add trace2 regions to wt-status Jeff Hostetler via GitGitGadget
2019-01-22 21:22 ` [PATCH 05/14] trace2:data: add editor/pager child classification Jeff Hostetler via GitGitGadget
2019-01-22 21:22 ` [PATCH 06/14] trace2:data: add trace2 sub-process classification Jeff Hostetler via GitGitGadget
2019-01-22 21:22 ` [PATCH 07/14] trace2:data: add trace2 transport child classification Jeff Hostetler via GitGitGadget
2019-01-22 21:22 ` [PATCH 09/14] trace2:data: add trace2 instrumentation to index read/write Jeff Hostetler via GitGitGadget
2019-01-22 21:22 ` [PATCH 08/14] trace2:data: add trace2 hook classification Jeff Hostetler via GitGitGadget
2019-01-22 21:22 ` [PATCH 10/14] pack-objects: add trace2 regions Derrick Stolee via GitGitGadget
2019-01-23  1:19   ` Derrick Stolee
2019-01-22 21:22 ` [PATCH 11/14] trace2:data: add subverb to checkout command Jeff Hostetler via GitGitGadget
2019-01-22 21:22 ` [PATCH 12/14] trace2:data: add subverb to reset command Jeff Hostetler via GitGitGadget
2019-01-22 21:22 ` [PATCH 13/14] trace2:data: add subverb for rebase Jeff Hostetler via GitGitGadget
2019-01-22 21:22 ` [PATCH 14/14] trace2: t/helper/test-trace2, t0210.sh, t0211.sh, t0212.sh Jeff Hostetler via GitGitGadget
2019-01-22 23:21 ` [PATCH 00/14] Trace2 tracing facility Junio C Hamano
2019-01-25 20:03 ` Josh Steadmon
2019-01-30 18:45   ` Jeff Hostetler
2019-01-28 16:15 ` Jeff Hostetler
2019-01-28 18:07   ` Junio C Hamano
2019-01-28 21:47 ` [PATCH v2 " Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 01/14] trace2: Documentation/technical/api-trace2.txt Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 02/14] trace2: create new combined trace facility Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 03/14] trace2: collect platform-specific process information Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 04/14] trace2:data: add trace2 regions to wt-status Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 05/14] trace2:data: add editor/pager child classification Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 06/14] trace2:data: add trace2 sub-process classification Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 07/14] trace2:data: add trace2 transport child classification Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 08/14] trace2:data: add trace2 hook classification Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 09/14] trace2:data: add trace2 instrumentation to index read/write Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 10/14] pack-objects: add trace2 regions Derrick Stolee via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 11/14] trace2:data: add subverb to checkout command Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 12/14] trace2:data: add subverb to reset command Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 13/14] trace2:data: add subverb for rebase Jeff Hostetler via GitGitGadget
2019-01-28 21:47   ` [PATCH v2 14/14] trace2: t/helper/test-trace2, t0210.sh, t0211.sh, t0212.sh Jeff Hostetler via GitGitGadget
2019-01-28 22:23     ` Junio C Hamano
2019-01-29 22:08       ` Jeff Hostetler
2019-01-30 19:51   ` [PATCH v3 00/14] Trace2 tracing facility Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 01/14] trace2: Documentation/technical/api-trace2.txt Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 02/14] trace2: create new combined trace facility Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 03/14] trace2: collect platform-specific process information Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 04/14] trace2:data: add trace2 regions to wt-status Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 05/14] trace2:data: add editor/pager child classification Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 06/14] trace2:data: add trace2 sub-process classification Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 07/14] trace2:data: add trace2 transport child classification Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 08/14] trace2:data: add trace2 hook classification Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 09/14] trace2:data: add trace2 instrumentation to index read/write Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 10/14] pack-objects: add trace2 regions Derrick Stolee via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 12/14] trace2:data: add subverb to reset command Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 11/14] trace2:data: add subverb to checkout command Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 13/14] trace2:data: add subverb for rebase Jeff Hostetler via GitGitGadget
2019-01-30 19:51     ` [PATCH v3 14/14] trace2: t/helper/test-trace2, t0210.sh, t0211.sh, t0212.sh Jeff Hostetler via GitGitGadget
2019-01-30 20:56     ` [PATCH v4 00/14] Trace2 tracing facility Jeff Hostetler via GitGitGadget
2019-01-30 20:56       ` [PATCH v4 01/14] trace2: Documentation/technical/api-trace2.txt Jeff Hostetler via GitGitGadget
2019-01-31 14:11         ` SZEDER Gábor
2019-01-31 22:33           ` Jeff Hostetler
2019-01-31 23:39             ` Junio C Hamano
2019-01-30 20:56       ` [PATCH v4 02/14] trace2: create new combined trace facility Jeff Hostetler via GitGitGadget
2019-01-30 20:56       ` [PATCH v4 04/14] trace2:data: add trace2 regions to wt-status Jeff Hostetler via GitGitGadget
2019-01-30 20:56       ` [PATCH v4 03/14] trace2: collect platform-specific process information Jeff Hostetler via GitGitGadget
2019-01-31 23:15         ` SZEDER Gábor
2019-02-01 11:12           ` Jeff Hostetler
2019-01-30 20:56       ` [PATCH v4 05/14] trace2:data: add editor/pager child classification Jeff Hostetler via GitGitGadget
2019-01-30 20:56       ` [PATCH v4 06/14] trace2:data: add trace2 sub-process classification Jeff Hostetler via GitGitGadget
2019-01-30 20:56       ` [PATCH v4 07/14] trace2:data: add trace2 transport child classification Jeff Hostetler via GitGitGadget
2019-01-30 20:56       ` [PATCH v4 08/14] trace2:data: add trace2 hook classification Jeff Hostetler via GitGitGadget
2019-01-30 20:56       ` [PATCH v4 09/14] trace2:data: add trace2 instrumentation to index read/write Jeff Hostetler via GitGitGadget
2019-01-30 20:56       ` [PATCH v4 10/14] pack-objects: add trace2 regions Derrick Stolee via GitGitGadget
2019-01-30 20:56       ` [PATCH v4 11/14] trace2:data: add subverb to checkout command Jeff Hostetler via GitGitGadget
2019-01-30 20:56       ` [PATCH v4 12/14] trace2:data: add subverb to reset command Jeff Hostetler via GitGitGadget
2019-01-30 20:56       ` [PATCH v4 13/14] trace2:data: add subverb for rebase Jeff Hostetler via GitGitGadget
2019-01-30 20:56       ` [PATCH v4 14/14] trace2: t/helper/test-trace2, t0210.sh, t0211.sh, t0212.sh Jeff Hostetler via GitGitGadget
2019-01-31 23:28         ` SZEDER Gábor
2019-01-31 23:41           ` Junio C Hamano
2019-02-01 11:08             ` Jeff Hostetler
2019-01-31 18:46       ` [PATCH v4 00/14] Trace2 tracing facility Junio C Hamano
2019-02-01 17:58       ` [PATCH v5 00/15] " Jeff Hostetler via GitGitGadget
2019-02-01 17:58         ` [PATCH v5 01/15] trace2: Documentation/technical/api-trace2.txt Jeff Hostetler via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 02/15] trace2: create new combined trace facility Jeff Hostetler via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 03/15] trace2: collect Windows-specific process information Jeff Hostetler via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 04/15] trace2:data: add trace2 regions to wt-status Jeff Hostetler via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 05/15] trace2:data: add editor/pager child classification Jeff Hostetler via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 06/15] trace2:data: add trace2 sub-process classification Jeff Hostetler via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 07/15] trace2:data: add trace2 transport child classification Jeff Hostetler via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 08/15] trace2:data: add trace2 hook classification Jeff Hostetler via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 09/15] trace2:data: add trace2 instrumentation to index read/write Jeff Hostetler via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 10/15] trace2:data: pack-objects: add trace2 regions Derrick Stolee via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 11/15] trace2:data: add subverb to checkout command Jeff Hostetler via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 12/15] trace2:data: add subverb to reset command Jeff Hostetler via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 13/15] trace2:data: add subverb for rebase Jeff Hostetler via GitGitGadget
2019-02-01 17:59         ` [PATCH v5 14/15] trace2: t/helper/test-trace2, t0210.sh, t0211.sh, t0212.sh Jeff Hostetler via GitGitGadget
2019-02-13 13:15           ` Ævar Arnfjörð Bjarmason
2019-02-01 17:59         ` [PATCH v5 15/15] trace2: add for_each macros to clang-format Jeff Hostetler via GitGitGadget
2019-02-06 17:15         ` [PATCH v6 00/15] Trace2 tracing facility Jeff Hostetler via GitGitGadget
2019-02-06 17:15           ` [PATCH v6 01/15] trace2: Documentation/technical/api-trace2.txt Jeff Hostetler via GitGitGadget
2019-02-06 17:15           ` [PATCH v6 02/15] trace2: create new combined trace facility Jeff Hostetler via GitGitGadget
2019-02-15 16:00             ` Ævar Arnfjörð Bjarmason
2019-02-15 17:57               ` Jeff Hostetler
2019-02-06 17:15           ` [PATCH v6 03/15] trace2: collect Windows-specific process information Jeff Hostetler via GitGitGadget
2019-02-06 17:15           ` [PATCH v6 04/15] trace2:data: add trace2 regions to wt-status Jeff Hostetler via GitGitGadget
2019-02-06 17:15           ` [PATCH v6 05/15] trace2:data: add editor/pager child classification Jeff Hostetler via GitGitGadget
2019-02-06 17:15           ` [PATCH v6 06/15] trace2:data: add trace2 sub-process classification Jeff Hostetler via GitGitGadget
2019-02-06 17:15           ` [PATCH v6 07/15] trace2:data: add trace2 transport child classification Jeff Hostetler via GitGitGadget
2019-02-06 17:16           ` [PATCH v6 09/15] trace2:data: add trace2 instrumentation to index read/write Jeff Hostetler via GitGitGadget
2019-02-06 17:16           ` [PATCH v6 08/15] trace2:data: add trace2 hook classification Jeff Hostetler via GitGitGadget
2019-02-06 17:16           ` [PATCH v6 10/15] trace2:data: pack-objects: add trace2 regions Derrick Stolee via GitGitGadget
2019-02-06 17:16           ` [PATCH v6 11/15] trace2:data: add subverb to checkout command Jeff Hostetler via GitGitGadget
2019-02-06 17:16           ` [PATCH v6 12/15] trace2:data: add subverb to reset command Jeff Hostetler via GitGitGadget
2019-02-06 17:16           ` [PATCH v6 13/15] trace2:data: add subverb for rebase Jeff Hostetler via GitGitGadget
2019-02-06 17:16           ` [PATCH v6 14/15] trace2: t/helper/test-trace2, t0210.sh, t0211.sh, t0212.sh Jeff Hostetler via GitGitGadget
2019-02-06 17:16           ` [PATCH v6 15/15] trace2: add for_each macros to clang-format Jeff Hostetler via GitGitGadget
2019-02-14 12:33           ` [PATCH v6 00/15] Trace2 tracing facility Ævar Arnfjörð Bjarmason
2019-02-15 17:25             ` Jeff Hostetler
2019-03-17 14:22               ` Ævar Arnfjörð Bjarmason
2019-03-21 14:30                 ` Johannes Schindelin
2019-03-21 14:48                   ` Ævar Arnfjörð Bjarmason
2019-03-22 13:17                     ` Johannes Schindelin
2019-03-22 14:01                       ` Jeff Hostetler [this message]
2019-03-22 14:53                         ` Ævar Arnfjörð Bjarmason
2019-03-22 15:21                           ` Jeff Hostetler
2019-02-22 22:24           ` [PATCH v7 " Jeff Hostetler via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 01/15] trace2: Documentation/technical/api-trace2.txt Jeff Hostetler via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 02/15] trace2: create new combined trace facility Jeff Hostetler via GitGitGadget
2019-05-10 17:28               ` SZEDER Gábor
2019-05-10 19:54                 ` Derrick Stolee
2019-02-22 22:25             ` [PATCH v7 03/15] trace2: collect Windows-specific process information Jeff Hostetler via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 04/15] trace2:data: add trace2 regions to wt-status Jeff Hostetler via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 05/15] trace2:data: add editor/pager child classification Jeff Hostetler via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 07/15] trace2:data: add trace2 transport " Jeff Hostetler via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 06/15] trace2:data: add trace2 sub-process classification Jeff Hostetler via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 08/15] trace2:data: add trace2 hook classification Jeff Hostetler via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 09/15] trace2:data: add trace2 instrumentation to index read/write Jeff Hostetler via GitGitGadget
2019-05-10 13:37               ` [PATCH] trace2: fix up a missing "leave" entry point Ævar Arnfjörð Bjarmason
2019-05-10 13:45                 ` Derrick Stolee
2019-05-20 16:50                 ` Jeff Hostetler
2019-02-22 22:25             ` [PATCH v7 10/15] trace2:data: pack-objects: add trace2 regions Derrick Stolee via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 11/15] trace2:data: add subverb to checkout command Jeff Hostetler via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 12/15] trace2:data: add subverb to reset command Jeff Hostetler via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 13/15] trace2:data: add subverb for rebase Jeff Hostetler via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 14/15] trace2: t/helper/test-trace2, t0210.sh, t0211.sh, t0212.sh Jeff Hostetler via GitGitGadget
2019-02-22 22:25             ` [PATCH v7 15/15] trace2: add for_each macros to clang-format Jeff Hostetler via GitGitGadget
2019-01-31 14:38     ` [PATCH v3 00/14] Trace2 tracing facility SZEDER Gábor
2019-01-31 14:53       ` Jeff Hostetler
2019-01-31 18:51         ` Junio C Hamano
2019-01-31 19:45           ` Jeff Hostetler
2019-01-31 22:11             ` Jeff Hostetler
2019-01-31 23:30               ` Junio C Hamano

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