b640313110
Let's start with how create a new directory cache after the last one
becomes invalid (e.g. because its dir mtime has changed...). In
open_cached_dir():
1. We start out with valid_cached_dir() returning false, which should
call invalidate_directory() to put a directory state back to
initial state, no untracked entries (untracked_nr zero), no sub
directory traversal (dirs[].recurse zero).
2. Since the cache cannot be used, we go the slow path opendir() and
go through items one by one via readdir(). All the directories on
disk will be added back to the cache (if not already exist in
dirs[]) and its flag "recurse" gets changed to one to note that
it's part of the cached dir travesal next time.
3. By the time we reach close_cached_dir() we should have a good
subdir list in dirs[]. Those with "recurse" flag set are the ones
present in the on-disk directory. The directory is now marked
"valid".
Next time read_directory() is called, since the directory is marked
valid, it will skip readdir(), go fast path and traverse through
dirs[] array instead.
Steps one and two need some tight cooperation. If a subdir is removed,
readdir() will not find it and of course we cannot examine/invalidate
it. To make sure removed directories on disk are gone from the cache,
step one must make sure recurse flag of all subdirs are zero.
But that's not true. If "valid" flag is already false, there is a
chance we go straight to the end of valid_cached_dir() without calling
invalidate_directory(). Or we fail to meet the "if (untracked-valid)"
condition and skip over the invalidate_directory().
After step 3, we mark the cache valid. Any stale subdir with incorrect
recurse flag becomes a real subdir next time we traverse the directory
using dirs[] array.
We could avoid this by making sure invalidate_directory() is always
called (therefore dirs[].recurse cleared) at the beginning of
open_cached_dir(). Which is what this patch does.
As to how we get into this situation, the key in the test is this
command
git checkout master
where "one/file" is replaced with "one" in the index. This index
update triggers untracked_cache_invalidate_path(), which clears valid
flag of the root directory while keeping "recurse" flag on the subdir
"one" on. On the next git-status, we go through steps 1-3 above and
save an incorrect cache on disk. The second git-status blindly follows
the bad cache data and shows the problem.
This is arguably because of a bad design where "recurse" flag plays
double roles: whether a directory should be saved on disk, and whether
it is part of a directory traversal.
We need to keep recurse flag set at "checkout master" because of the
first role: we need to keep subdir caches (dir "two" for example has
not been touched at all, no reason to throw its cache away).
As long as we make sure to ignore/reset "recurse" flag at the
beginning of a directory traversal, we're good. But maybe eventually
we should separate these two roles.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
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 user discussion and development of Git take place on the Git mailing list -- everyone is welcome to post bug reports, feature requests, comments and patches to git@vger.kernel.org (read Documentation/SubmittingPatches for instructions on patch submission). To subscribe to the list, send an email with just "subscribe git" in the body to majordomo@vger.kernel.org. The mailing list archives are available at https://public-inbox.org/git/, http://marc.info/?l=git and other archival sites.
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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