FreeBSD can lie when asked mtime of a directory, which made the
untracked cache code to fall back to a slow-path, which in turn
caused tests in t7063 to fail because it wanted to verify the
behaviour of the fast-path.
* nd/fbsd-lazy-mtime:
t7063: work around FreeBSD's lazy mtime update feature
Let's start with the commit message of [1] from freebsd.git [2]
Sync timestamp changes for inodes of special files to disk as late
as possible (when the inode is reclaimed). Temporarily only do
this if option UFS_LAZYMOD configured and softupdates aren't
enabled. UFS_LAZYMOD is intentionally left out of
/sys/conf/options.
This is mainly to avoid almost useless disk i/o on battery powered
machines. It's silly to write to disk (on the next sync or when
the inode becomes inactive) just because someone hit a key or
something wrote to the screen or /dev/null.
PR: 5577 [3]
The short version of that, in the context of t7063, is that when a
directory is updated, its mtime may be updated later, not
immediately. This can be shown with a simple command sequence
date; sleep 1; touch abc; rm abc; sleep 10; ls -lTd .
One would expect that the date shown in `ls` would be one second from
`date`, but it's 10 seconds later. If we put another `ls -lTd .` in
front of `sleep 10`, then the date of the last `ls` comes as
expected. The first `ls` somehow forces mtime to be updated.
t7063 is really sensitive to directory mtime. When mtime is too "new",
git code suspects racy timestamps and will not trigger the shortcut in
untracked cache, in t7063.24 and eventually be detected in t7063.27
We have two options thanks to this special FreeBSD feature:
1) Stop supporting untracked cache on FreeBSD. Skip t7063 entirely
when running on FreeBSD
2) Work around this problem (using the same 'ls' trick) and continue
to support untracked cache on FreeBSD
I initially wanted to go with 1) because I didn't know the exact
nature of this feature and feared that it would make untracked cache
work unreliably, using the cached version when it should not.
Since the behavior of this thing is clearer now. The picture is not
that bad. If this indeed happens often, untracked cache would assume
racy condition more often and _fall back_ to non-untracked cache code
paths. Which means it may be less effective, but it will not show
wrong things.
This patch goes with option 2.
PS. For those who want to look further in FreeBSD source code, this
flag is now called IN_LAZYMOD. I can see it's effective in ext2 and
ufs. zfs is not affected.
[1] 660e6408e6df99a20dacb070c5e7f9739efdf96d
[2] git://github.com/freebsd/freebsd.git
[3] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=5577
Reported-by: Eric Wong <e@80x24.org>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Similar to $EMPTY_TREE this makes it easier to recognize this special
SHA-1 and change hash later.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we know that mtime on directory as given by the environment
is usable for the purpose of untracked cache, we may want the
untracked cache to be always used without any mtime test or
kernel name check being performed.
Also when we know that mtime is not usable for the purpose of
untracked cache, for example because the repo is shared over a
network file system, we may want the untracked-cache to be
automatically removed from the index.
Allow the user to express such preference by setting the
'core.untrackedCache' configuration variable, which can take
'keep', 'false', or 'true' and default to 'keep'.
When read_index_from() is called, it now adds or removes the
untracked cache in the index to respect the value of this
variable. So it does nothing if the value is `keep` or if the
variable is unset; it adds the untracked cache if the value is
`true`; and it removes the cache if the value is `false`.
`git update-index --[no-|force-]untracked-cache` still adds the
untracked cache to, or removes it, from the index, but this
shows a warning if it goes against the value of
core.untrackedCache, because the next time the index is read
the untracked cache will be added or removed if the
configuration is set to do so.
Also `--untracked-cache` used to check that the underlying
operating system and file system change `st_mtime` field of a
directory if files are added or deleted in that directory. But
because those tests take a long time, `--untracked-cache` no
longer performs them. Instead, there is now
`--test-untracked-cache` to perform the tests. This change
makes `--untracked-cache` the same as `--force-untracked-cache`.
This last change is backward incompatible and should be
mentioned in the release notes.
Helped-by: Duy Nguyen <pclouds@gmail.com>
Helped-by: Torsten Bögershausen <tboegi@web.de>
Helped-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
read-cache: Duy'sfixup
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Dirty the test worktree's root directory, as the test expects.
When testing the untracked-cache, we previously assumed that checking
out master would be sufficient to mark the mtime of the worktree's
root directory as racily-dirty. But sometimes, the checkout would
happen at 12345.999 seconds and the status at 12346.001 seconds,
meaning that the worktree's root directory would not be racily-dirty.
And since it was not truly dirty, occasionally the test would fail.
By making the root truly dirty, the test will always succeed.
Tested by running a few hundred times.
Signed-off-by: David Turner <dturner@twopensource.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
First, the current code in untracked_cache_invalidate_path() is wrong
because it can only handle paths "a" or "a/b", not "a/b/c" because
lookup_untracked() only looks for entries directly under the given
directory. In the last case, it will look for the entry "b/c" in
directory "a" instead. This means if you delete or add an entry in a
subdirectory, untracked cache may become out of date because it does not
invalidate properly. This is noticed by David Turner.
The second problem is about invalidation inside a fully untracked/excluded
directory. In this case we may have to invalidate back to root. See the
comment block for detail.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Previously, some calls lookup_untracked would pass a full path. But
lookup_untracked assumes that the portion of the path up to and
including to the untracked_cache_dir has been removed. So
lookup_untracked would be looking in the untracked_cache for 'foo' for
'foo/bar' (instead of just looking for 'bar'). This would cause
untracked cache corruption.
Instead, treat_directory learns to track the base length of the parent
directory, so that only the last path component is passed to
lookup_untracked.
Helped-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: David Turner <dturner@twopensource.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When in the middle of t7063, we are sure untracked cache is supported,
so we can use --force-untracked-cache to skip the support detection
phase and save a few seconds. It's also good that --force-untracked-cache
is exercised in the test suite.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Remove a check that would disable the untracked cache for sparse
checkouts. Add tests that ensure that the untracked cache works with
sparse checkouts -- specifically considering the case that a file
foo/bar is checked out, but foo/.gitignore is not.
Signed-off-by: David Turner <dturner@twopensource.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When t7063 starts, it runs "update-index --untracked-cache"
to see if we support the untracked cache. Its output goes
straight to stderr, even if the test is not run with "-v".
Let's wrap it in a prereq that will hide the output by
default, but show it with "-v".
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
