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>
Nguyễn Thái Ngọc Duy
Alex Vandiver
Ben Peart