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From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Josh Steadmon <steadmon@google.com>,
	git@vger.kernel.org, git@jeffhostetler.com
Subject: Re: [PATCH v3 1/1] trace2: write to directory targets
Date: Sun, 24 Mar 2019 15:51:05 +0100	[thread overview]
Message-ID: <87a7hkcome.fsf@evledraar.gmail.com> (raw)
In-Reply-To: <xmqqlg14pi2x.fsf@gitster-ct.c.googlers.com>


On Sun, Mar 24 2019, Junio C Hamano wrote:

> Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
>
>> The reason I'm raising this is that it seems like sweeping an existing
>> issue under the rug. We document that the "sid" is "unique", and it's just:
>>
>>     <nanotime / 1000 (i.e. *nix time in microseconds)>-<pid>
>
> If it is just that, then it cannot be unique, can it?
>
> Let's just fix the wrong doc and move on.

I don't see why we wouldn't just fix the SID generation & move on if
we're already carrying code purely as a work-around for it not being
unique enough.

Of course nothing is *guaranteed* to be unique, not even a 128-bit
UUID. The point is to pick something that's "unique enough" given the
problem space, which is already one where we'll ignore I/O errors on
writing the file unless you opt-in to a warning.

And it's a very useful property to have the SID be a) unique enough like
that so you can use a unique index for "git events" b) fixed-width
(which the current one *isn't*), so you can use fixed-with indexes in
some logging databases c) as a bonus, be human-readable at a glance,
hence spending slightly more space on the the YYYMM.. format in my
suggested SID format.

I can write that patch, but first it's useful to know if this is a case
Josh is running into, or if it's just a guard out of paranoia.

  reply	other threads:[~2019-03-24 14:51 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-13 23:33 [PATCH 0/2] Randomize / timestamp trace2 targets Josh Steadmon
2019-03-13 23:33 ` [PATCH 1/2] date: make get_time() public Josh Steadmon
2019-03-13 23:33 ` [PATCH 2/2] trace2: randomize/timestamp trace2 targets Josh Steadmon
2019-03-13 23:49   ` Ævar Arnfjörð Bjarmason
2019-03-15 18:39     ` Jeff Hostetler
2019-03-15 19:26       ` Ævar Arnfjörð Bjarmason
2019-03-15 20:14         ` Jeff Hostetler
2019-03-15 20:43     ` Josh Steadmon
2019-03-15 20:49       ` Josh Steadmon
2019-03-18  1:40         ` Junio C Hamano
2019-03-19  3:17           ` Jeff King
2019-03-14  0:16   ` Jeff King
2019-03-14  6:07     ` Junio C Hamano
2019-03-14 14:34 ` [PATCH 0/2] Randomize / timestamp " Johannes Schindelin
2019-03-15 20:37   ` Josh Steadmon
2019-03-15 19:18 ` Jeff Hostetler
2019-03-15 20:38   ` Josh Steadmon
2019-03-18 12:50     ` Jeff Hostetler
2019-03-21  0:16 ` [PATCH v2 0/1] Write trace2 output to directories Josh Steadmon
2019-03-21  0:16   ` [PATCH v2 1/1] trace2: write to directory targets Josh Steadmon
2019-03-21  2:04     ` Junio C Hamano
2019-03-21 17:43       ` Jeff Hostetler
2019-03-22  3:30         ` Junio C Hamano
2019-03-22 14:20           ` Jeff Hostetler
2019-03-21 21:09 ` [PATCH v3 0/1] Write trace2 output to directories Josh Steadmon
2019-03-21 21:09   ` [PATCH v3 1/1] trace2: write to directory targets Josh Steadmon
2019-03-23 20:44     ` Ævar Arnfjörð Bjarmason
2019-03-24 12:33       ` Junio C Hamano
2019-03-24 14:51         ` Ævar Arnfjörð Bjarmason [this message]
2019-03-25  2:21           ` Junio C Hamano
2019-03-25  8:21             ` Ævar Arnfjörð Bjarmason
2019-03-25 16:29       ` Jeff Hostetler
2019-03-21 21:16   ` [PATCH v3 0/1] Write trace2 output to directories Jeff Hostetler
2019-03-22  5:23     ` Junio C Hamano

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