Let's measure the time taken to request and receive FSMonitor data
via the hook API and the size of the response.
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Without this bug fix, t7519's four "status doesn't detect unreported
modifications" test cases would fail occasionally (and, oddly enough,
*a lot* more frequently on Windows).
The reason is that these test cases intentionally use the side effect of
`git status` to re-write the index if any updates were detected: they
first clean the worktree, run `git status` to update the index as well
as show the output to the casual reader, then make the worktree dirty
again and expect no changes to reported if running with a mocked
fsmonitor hook.
The problem with this strategy was that the index was written during
said `git status` on the clean worktree for the *wrong* reason: not
because the index was marked as changed (it wasn't), but because the
recorded mtimes were racy with the index' own mtime.
As the mtime granularity on Windows is 100 nanoseconds (see e.g.
https://docs.microsoft.com/en-us/windows/desktop/SysInfo/file-times),
the mtimes of the files are often enough *not* racy with the index', so
that that `git status` call currently does not always update the index
(including the fsmonitor extension), causing the test case to fail.
The obvious fix: if we change *any* index entry's `CE_FSMONITOR_VALID`
flag, we should also mark the index as changed. That will cause the
index to be written upon `git status`, *including* an updated fsmonitor
extension.
Side note: Even though the reader might think that the t7519 issue
should be *much* more prevalent on Linux, given that the ext4 filesystem
(that seems to be used by every Linux distribution) stores mtimes in
nanosecond precision. However, ext4 uses `current_kernel_time()` (see
https://unix.stackexchange.com/questions/11599#comment762968_11599; it
is *amazingly* hard to find any proper source of information about such
ext4 questions) whose accuracy seems to depend on many factors but is
safely worse than the 100-nanosecond granularity of NTFS (again, it is
*horribly* hard to find anything remotely authoritative about this
question). So it seems that the racy index condition that hid the bug
fixed by this patch simply is a lot more likely on Linux than on
Windows. But not impossible ;-)
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
There has been a push to remove extern from function declarations.
Remove some instances of "extern" for function declarations which are
caught by Coccinelle. Note that Coccinelle has some difficulty with
processing functions with `__attribute__` or varargs so some `extern`
declarations are left behind to be dealt with in a future patch.
This was the Coccinelle patch used:
@@
type T;
identifier f;
@@
- extern
T f(...);
and it was run with:
$ git ls-files \*.{c,h} |
grep -v ^compat/ |
xargs spatch --sp-file contrib/coccinelle/noextern.cocci --in-place
Files under `compat/` are intentionally excluded as some are directly
copied from external sources and we should avoid churning them as much
as possible.
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
I looped over the toplevel header files, creating a temporary two-line C
program for each consisting of
#include "git-compat-util.h"
#include $HEADER
This patch is the result of manually fixing errors in compiling those
tiny programs.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
read_directory() code ignores all paths named ".git" even if it's not
a valid git repository. See treat_path() for details. Since ".git" is
basically invisible to read_directory(), when we are asked to
invalidate a path that contains ".git", we can safely ignore it
because the slow path would not consider it anyway.
This helps when fsmonitor is used and we have a real ".git" repo at
worktree top. Occasionally .git/index will be updated and if the
fsmonitor hook does not filter it, untracked cache is asked to
invalidate the path ".git/index".
Without this patch, we invalidate the root directory unncessarily,
which:
- makes read_directory() fall back to slow path for root directory
(slower)
- makes the index dirty (because UNTR extension is updated). Depending
on the index size, writing it down could also be slow.
A note about the new "safe_path" knob. Since this new check could be
relatively expensive, avoid it when we know it's not needed. If the
path comes from the index, it can't contain ".git". If it does
contain, we may be screwed up at many more levels, not just this one.
Noticed-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ba1b9cac ("fsmonitor: delay updating state until after split index
is merged", 2017-10-27) resolved the problem of the fsmonitor data
being applied to the non-base index when reading; however, a similar
problem exists when writing the index. Specifically, writing of the
fsmonitor extension happens only after the work to split the index
has been applied -- as such, the information in the index is only
for the non-"base" index, and thus the extension information
contains only partial data.
When saving, compute the ewah bitmap before the index is split, and
store it in the fsmonitor_dirty field, mirroring the behavior that
occurred during reading. fsmonitor_dirty is kept from being leaked by
being freed when the extension data is written -- which always happens
precisely once, no matter the split index configuration.
Signed-off-by: Alex Vandiver <alexmv@dropbox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When the index is read from disk, the fsmonitor index extension is used
to flag the last known potentially dirty index entries. The registered
core.fsmonitor command is called with the time the index was last
updated and returns the list of files changed since that time. This list
is used to flag any additional dirty cache entries and untracked cache
directories.
We can then use this valid state to speed up preload_index(),
ie_match_stat(), and refresh_cache_ent() as they do not need to lstat()
files to detect potential changes for those entries marked
CE_FSMONITOR_VALID.
In addition, if the untracked cache is turned on valid_cached_dir() can
skip checking directories for new or changed files as fsmonitor will
invalidate the cache only for those directories that have been
identified as having potential changes.
To keep the CE_FSMONITOR_VALID state accurate during git operations;
when git updates a cache entry to match the current state on disk,
it will now set the CE_FSMONITOR_VALID bit.
Inversely, anytime git changes a cache entry, the CE_FSMONITOR_VALID bit
is cleared and the corresponding untracked cache directory is marked
invalid.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
