Since fetch often deals with object-ids we don't have (yet),
it's an easy mistake for it to use a function like
parse_object() that gives the correct result (e.g., NULL)
but does so very slowly (because after failing to find the
object, we re-scan the pack directory looking for new
packs).
The regular test suite won't catch this because the end
result is correct, but we would want to know about
performance regressions, too. Let's add a test to the
regression suite.
Note that this uses a synthetic repository that has a large
number of packs. That's not ideal, as it means we're not
testing what "normal" users see (in fact, some of these
problems have existed for ages without anybody noticing
simply because a rescan on a normal repository just isn't
that expensive).
So what we're really looking for here is the spike you'd
notice in a pathological case (a lot of unknown objects
coming into a repo with a lot of packs). If that's fast,
then the normal cases should be, too.
Note that the test also makes liberal use of $MODERN_GIT for
setup; some of these regressions go back a ways, and we
should be able to use it to find the problems there.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an
unusually rich command set that provides both high-level operations
and full access to internals.
Git is an Open Source project covered by the GNU General Public
License version 2 (some parts of it are under different licenses,
compatible with the GPLv2). It was originally written by Linus
Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/
including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see
Documentation/giteveryday.txt for a useful minimum set of commands, and
Documentation/git-.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with man gittutorial or git help tutorial, and the
documentation of each command with man git-<commandname> or git help <commandname>.
CVS users may also want to read Documentation/gitcvs-migration.txt
(man gitcvs-migration or git help cvs-migration if git is
installed).
The maintainer frequently sends the "What's cooking" reports that
list the current status of various development topics to the mailing
list. The discussion following them give a good reference for
project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very
first version. He described the tool as "the stupid content tracker"
and the name as (depending on your mood):
random three-letter combination that is pronounceable, and not
actually used by any common UNIX command. The fact that it is a
mispronunciation of "get" may or may not be relevant.
stupid. contemptible and despicable. simple. Take your pick from the
dictionary of slang.
"global information tracker": you're in a good mood, and it actually
works for you. Angels sing, and a light suddenly fills the room.
"goddamn idiotic truckload of sh*t": when it breaks
