Make use of the stream_loose_object() function introduced in the
preceding commit to unpack large objects. Before this we'd need to
malloc() the size of the blob before unpacking it, which could cause
OOM with very large blobs.
We could use the new streaming interface to unpack all blobs, but
doing so would be much slower, as demonstrated e.g. with this
benchmark using git-hyperfine[0]:
rm -rf /tmp/scalar.git &&
git clone --bare https://github.com/Microsoft/scalar.git /tmp/scalar.git &&
mv /tmp/scalar.git/objects/pack/*.pack /tmp/scalar.git/my.pack &&
git hyperfine \
-r 2 --warmup 1 \
-L rev origin/master,HEAD -L v "10,512,1k,1m" \
-s 'make' \
-p 'git init --bare dest.git' \
-c 'rm -rf dest.git' \
'./git -C dest.git -c core.bigFileThreshold={v} unpack-objects </tmp/scalar.git/my.pack'
Here we'll perform worse with lower core.bigFileThreshold settings
with this change in terms of speed, but we're getting lower memory use
in return:
Summary
'./git -C dest.git -c core.bigFileThreshold=10 unpack-objects </tmp/scalar.git/my.pack' in 'origin/master' ran
1.01 ± 0.01 times faster than './git -C dest.git -c core.bigFileThreshold=1k unpack-objects </tmp/scalar.git/my.pack' in 'origin/master'
1.01 ± 0.01 times faster than './git -C dest.git -c core.bigFileThreshold=1m unpack-objects </tmp/scalar.git/my.pack' in 'origin/master'
1.01 ± 0.02 times faster than './git -C dest.git -c core.bigFileThreshold=1m unpack-objects </tmp/scalar.git/my.pack' in 'HEAD'
1.02 ± 0.00 times faster than './git -C dest.git -c core.bigFileThreshold=512 unpack-objects </tmp/scalar.git/my.pack' in 'origin/master'
1.09 ± 0.01 times faster than './git -C dest.git -c core.bigFileThreshold=1k unpack-objects </tmp/scalar.git/my.pack' in 'HEAD'
1.10 ± 0.00 times faster than './git -C dest.git -c core.bigFileThreshold=512 unpack-objects </tmp/scalar.git/my.pack' in 'HEAD'
1.11 ± 0.00 times faster than './git -C dest.git -c core.bigFileThreshold=10 unpack-objects </tmp/scalar.git/my.pack' in 'HEAD'
A better benchmark to demonstrate the benefits of that this one, which
creates an artificial repo with a 1, 25, 50, 75 and 100MB blob:
rm -rf /tmp/repo &&
git init /tmp/repo &&
(
cd /tmp/repo &&
for i in 1 25 50 75 100
do
dd if=/dev/urandom of=blob.$i count=$(($i*1024)) bs=1024
done &&
git add blob.* &&
git commit -mblobs &&
git gc &&
PACK=$(echo .git/objects/pack/pack-*.pack) &&
cp "$PACK" my.pack
) &&
git hyperfine \
--show-output \
-L rev origin/master,HEAD -L v "512,50m,100m" \
-s 'make' \
-p 'git init --bare dest.git' \
-c 'rm -rf dest.git' \
'/usr/bin/time -v ./git -C dest.git -c core.bigFileThreshold={v} unpack-objects </tmp/repo/my.pack 2>&1 | grep Maximum'
Using this test we'll always use >100MB of memory on
origin/master (around ~105MB), but max out at e.g. ~55MB if we set
core.bigFileThreshold=50m.
The relevant "Maximum resident set size" lines were manually added
below the relevant benchmark:
'/usr/bin/time -v ./git -C dest.git -c core.bigFileThreshold=50m unpack-objects </tmp/repo/my.pack 2>&1 | grep Maximum' in 'origin/master' ran
Maximum resident set size (kbytes): 107080
1.02 ± 0.78 times faster than '/usr/bin/time -v ./git -C dest.git -c core.bigFileThreshold=512 unpack-objects </tmp/repo/my.pack 2>&1 | grep Maximum' in 'origin/master'
Maximum resident set size (kbytes): 106968
1.09 ± 0.79 times faster than '/usr/bin/time -v ./git -C dest.git -c core.bigFileThreshold=100m unpack-objects </tmp/repo/my.pack 2>&1 | grep Maximum' in 'origin/master'
Maximum resident set size (kbytes): 107032
1.42 ± 1.07 times faster than '/usr/bin/time -v ./git -C dest.git -c core.bigFileThreshold=100m unpack-objects </tmp/repo/my.pack 2>&1 | grep Maximum' in 'HEAD'
Maximum resident set size (kbytes): 107072
1.83 ± 1.02 times faster than '/usr/bin/time -v ./git -C dest.git -c core.bigFileThreshold=50m unpack-objects </tmp/repo/my.pack 2>&1 | grep Maximum' in 'HEAD'
Maximum resident set size (kbytes): 55704
2.16 ± 1.19 times faster than '/usr/bin/time -v ./git -C dest.git -c core.bigFileThreshold=512 unpack-objects </tmp/repo/my.pack 2>&1 | grep Maximum' in 'HEAD'
Maximum resident set size (kbytes): 4564
This shows that if you have enough memory this new streaming method is
slower the lower you set the streaming threshold, but the benefit is
more bounded memory use.
An earlier version of this patch introduced a new
"core.bigFileStreamingThreshold" instead of re-using the existing
"core.bigFileThreshold" variable[1]. As noted in a detailed overview
of its users in [2] using it has several different meanings.
Still, we consider it good enough to simply re-use it. While it's
possible that someone might want to e.g. consider objects "small" for
the purposes of diffing but "big" for the purposes of writing them
such use-cases are probably too obscure to worry about. We can always
split up "core.bigFileThreshold" in the future if there's a need for
that.
0. https://github.com/avar/git-hyperfine/
1. https://lore.kernel.org/git/20211210103435.83656-1-chiyutianyi@gmail.com/
2. https://lore.kernel.org/git/20220120112114.47618-5-chiyutianyi@gmail.com/
Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Helped-by: Derrick Stolee <stolee@gmail.com>
Helped-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
Signed-off-by: Han Xin <chiyutianyi@gmail.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As the name implies, "get_data(size)" will allocate and return a given
amount of memory. Allocating memory for a large blob object may cause the
system to run out of memory. Before preparing to replace calling of
"get_data()" to unpack large blob objects in latter commits, refactor
"get_data()" to reduce memory footprint for dry_run mode.
Because in dry_run mode, "get_data()" is only used to check the
integrity of data, and the returned buffer is not used at all, we can
allocate a smaller buffer and use it as zstream output. Make the function
return NULL in the dry-run mode, as no callers use the returned buffer.
The "find [...]objects/?? -type f | wc -l" test idiom being used here
is adapted from the same "find" use added to another test in
d9545c7f46 (fast-import: implement unpack limit, 2016-04-25).
Suggested-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
Signed-off-by: Han Xin <chiyutianyi@gmail.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A mechanism to pack unreachable objects into a "cruft pack",
instead of ejecting them into loose form to be reclaimed later, has
been introduced.
* tb/cruft-packs:
sha1-file.c: don't freshen cruft packs
builtin/gc.c: conditionally avoid pruning objects via loose
builtin/repack.c: add cruft packs to MIDX during geometric repack
builtin/repack.c: use named flags for existing_packs
builtin/repack.c: allow configuring cruft pack generation
builtin/repack.c: support generating a cruft pack
builtin/pack-objects.c: --cruft with expiration
reachable: report precise timestamps from objects in cruft packs
reachable: add options to add_unseen_recent_objects_to_traversal
builtin/pack-objects.c: --cruft without expiration
builtin/pack-objects.c: return from create_object_entry()
t/helper: add 'pack-mtimes' test-tool
pack-mtimes: support writing pack .mtimes files
chunk-format.h: extract oid_version()
pack-write: pass 'struct packing_data' to 'stage_tmp_packfiles'
pack-mtimes: support reading .mtimes files
Documentation/technical: add cruft-packs.txt
Teach "git repack --geometric" work better with "--keep-pack" and
avoid corrupting the repository when packsize limit is used.
* tb/geom-repack-with-keep-and-max:
builtin/repack.c: ensure that `names` is sorted
t7703: demonstrate object corruption with pack.packSizeLimit
repack: respect --keep-pack with geometric repack
"sparse-checkout" learns to work well with the sparse-index
feature.
* ds/sparse-sparse-checkout:
sparse-checkout: integrate with sparse index
p2000: add test for 'git sparse-checkout [add|set]'
sparse-index: complete partial expansion
sparse-index: partially expand directories
sparse-checkout: --no-sparse-index needs a full index
cache-tree: implement cache_tree_find_path()
sparse-index: introduce partially-sparse indexes
sparse-index: create expand_index()
t1092: stress test 'git sparse-checkout set'
t1092: refactor 'sparse-index contents' test
Introduce a filesystem-dependent mechanism to optimize the way the
bits for many loose object files are ensured to hit the disk
platter.
* ns/batch-fsync:
core.fsyncmethod: performance tests for batch mode
t/perf: add iteration setup mechanism to perf-lib
core.fsyncmethod: tests for batch mode
test-lib-functions: add parsing helpers for ls-files and ls-tree
core.fsync: use batch mode and sync loose objects by default on Windows
unpack-objects: use the bulk-checkin infrastructure
update-index: use the bulk-checkin infrastructure
builtin/add: add ODB transaction around add_files_to_cache
cache-tree: use ODB transaction around writing a tree
core.fsyncmethod: batched disk flushes for loose-objects
bulk-checkin: rebrand plug/unplug APIs as 'odb transactions'
bulk-checkin: rename 'state' variable and separate 'plugged' boolean
Deprecate non-cone mode of the sparse-checkout feature.
* en/sparse-cone-becomes-default:
Documentation: some sparsity wording clarifications
git-sparse-checkout.txt: mark non-cone mode as deprecated
git-sparse-checkout.txt: flesh out pattern set sections a bit
git-sparse-checkout.txt: add a new EXAMPLES section
git-sparse-checkout.txt: shuffle some sections and mark as internal
git-sparse-checkout.txt: update docs for deprecation of 'init'
git-sparse-checkout.txt: wording updates for the cone mode default
sparse-checkout: make --cone the default
tests: stop assuming --no-cone is the default mode for sparse-checkout
"git add -i" was rewritten in C some time ago and has been in
testing; the reimplementation is now exposed to general public by
default.
* js/use-builtin-add-i:
add -i: default to the built-in implementation
t2016: require the PERL prereq only when necessary
The tests that ensured merges stop when interfering local changes
are present did not make sure that local changes are preserved; now
they do.
* jc/t6424-failing-merge-preserve-local-changes:
t6424: make sure a failed merge preserves local changes
With the new http.curloptResolve configuration, the CURLOPT_RESOLVE
mechanism that allows cURL based applications to use pre-resolved
IP addresses for the requests is exposed to the scripts.
* cc/http-curlopt-resolve:
http: add custom hostname to IP address resolutions
We don't bother to freshen objects stored in a cruft pack individually
by updating the `.mtimes` file. This is because we can't portably `mmap`
and write into the middle of a file (i.e., to update the mtime of just
one object). Instead, we would have to rewrite the entire `.mtimes` file
which may incur some wasted effort especially if there a lot of cruft
objects and they are freshened infrequently.
Instead, force the freshening code to avoid an optimizing write by
writing out the object loose and letting it pick up a current mtime.
This works because we prefer the mtime of the loose copy of an object
when both a loose and packed one exist (whether or not the packed copy
comes from a cruft pack or not).
This could certainly do with a test and/or be included earlier in this
series/PR, but I want to wait until after I have a chance to clean up
the overly-repetitive nature of the cruft pack tests in general.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Expose the new `git repack --cruft` mode from `git gc` via a new opt-in
flag. When invoked like `git gc --cruft`, `git gc` will avoid exploding
unreachable objects as loose ones, and instead create a cruft pack and
`.mtimes` file.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When using cruft packs, the following race can occur when a geometric
repack that writes a MIDX bitmap takes place afterwords:
- First, create an unreachable object and do an all-into-one cruft
repack which stores that object in the repository's cruft pack.
- Then make that object reachable.
- Finally, do a geometric repack and write a MIDX bitmap.
Assuming that we are sufficiently unlucky as to select a commit from the
MIDX which reaches that object for bitmapping, then the `git
multi-pack-index` process will complain that that object is missing.
The reason is because we don't include cruft packs in the MIDX when
doing a geometric repack. Since the "make that object reachable" doesn't
necessarily mean that we'll create a new copy of that object in one of
the packs that will get rolled up as part of a geometric repack, it's
possible that the MIDX won't see any copies of that now-reachable
object.
Of course, it's desirable to avoid including cruft packs in the MIDX
because it causes the MIDX to store a bunch of objects which are likely
to get thrown away. But excluding that pack does open us up to the above
race.
This patch demonstrates the bug, and resolves it by including cruft
packs in the MIDX even when doing a geometric repack.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In servers which set the pack.window configuration to a large value, we
can wind up spending quite a lot of time finding new bases when breaking
delta chains between reachable and unreachable objects while generating
a cruft pack.
Introduce a handful of `repack.cruft*` configuration variables to
control the parameters used by pack-objects when generating a cruft
pack.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Expose a way to split the contents of a repository into a main and cruft
pack when doing an all-into-one repack with `git repack --cruft -d`, and
a complementary configuration variable.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In a previous patch, pack-objects learned how to generate a cruft pack
so long as no objects are dropped.
This patch teaches pack-objects to handle the case where a non-never
`--cruft-expiration` value is passed. This case is slightly more
complicated than before, because we want pack-objects to save
unreachable objects which would have been pruned when there is another
recent (i.e., non-prunable) unreachable object which reaches the other.
We'll call these objects "unreachable but reachable-from-recent".
Here is how pack-objects handles `--cruft-expiration`:
- Instead of adding all objects outside of the kept pack(s) into the
packing list, only handle the ones whose mtime is within the grace
period.
- Construct a reachability traversal whose tips are the
unreachable-but-recent objects.
- Then, walk along that traversal, stopping if we reach an object in
the kept pack. At each step along the traversal, we add the object
we are visiting to the packing list.
In the majority of these cases, any object we visit in this traversal
will already be in our packing list. But we will sometimes encounter
reachable-from-recent cruft objects, which we want to retain even if
they aged out of the grace period.
The most subtle point of this process is that we actually don't need to
bother to update the rescued object's mtime. Even though we will write
an .mtimes file with a value that is older than the expiration window,
it will continue to survive cruft repacks so long as any objects which
reach it haven't aged out.
That is, a future repack will also exclude that object from the initial
packing list, only to discover it later on when doing the reachability
traversal.
Finally, stopping early once an object is found in a kept pack is safe
to do because the kept packs ordinarily represent which packs will
survive after repacking. Assuming that it _isn't_ safe to halt a
traversal early would mean that there is some ancestor object which is
missing, which implies repository corruption (i.e., the complete set of
reachable objects isn't present).
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Teach `pack-objects` how to generate a cruft pack when no objects are
dropped (i.e., `--cruft-expiration=never`). Later patches will teach
`pack-objects` how to generate a cruft pack that prunes objects.
When generating a cruft pack which does not prune objects, we want to
collect all unreachable objects into a single pack (noting and updating
their mtimes as we accumulate them). Ordinary use will pass the result
of a `git repack -A` as a kept pack, so when this patch says "kept
pack", readers should think "reachable objects".
Generating a non-expiring cruft packs works as follows:
- Callers provide a list of every pack they know about, and indicate
which packs are about to be removed.
- All packs which are going to be removed (we'll call these the
redundant ones) are marked as kept in-core.
Any packs the caller did not mention (but are known to the
`pack-objects` process) are also marked as kept in-core. Packs not
mentioned by the caller are assumed to be unknown to them, i.e.,
they entered the repository after the caller decided which packs
should be kept and which should be discarded.
Since we do not want to include objects in these "unknown" packs
(because we don't know which of their objects are or aren't
reachable), these are also marked as kept in-core.
- Then, we enumerate all objects in the repository, and add them to
our packing list if they do not appear in an in-core kept pack.
This results in a new cruft pack which contains all known objects that
aren't included in the kept packs. When the kept pack is the result of
`git repack -A`, the resulting pack contains all unreachable objects.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the next patch, we will implement and test support for writing a
cruft pack via a special mode of `git pack-objects`. To make sure that
objects are written with the correct timestamps, and a new test-tool
that can dump the object names and corresponding timestamps from a given
`.mtimes` file.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git remote -v" now shows the list-objects-filter used during
fetching from the remote, if available.
* ac/remote-v-with-object-list-filters:
builtin/remote.c: teach `-v` to list filters for promisor remotes
With a recent update to refuse access to repositories of other
people by default, "sudo make install" and "sudo git describe"
stopped working. This series intends to loosen it while keeping
the safety.
* cb/path-owner-check-with-sudo:
t0034: add negative tests and allow git init to mostly work under sudo
git-compat-util: avoid failing dir ownership checks if running privileged
t: regression git needs safe.directory when using sudo
"git -c branch.autosetupmerge=simple branch $A $B" will set the $B
as $A's upstream only when $A and $B shares the same name, and "git
-c push.default=simple" on branch $A would push to update the
branch $A at the remote $B came from. Also more places use the
sole remote, if exists, before defaulting to 'origin'.
* tk/simple-autosetupmerge:
push: new config option "push.autoSetupRemote" supports "simple" push
push: default to single remote even when not named origin
branch: new autosetupmerge option 'simple' for matching branches
"git fetch --recurse-submodules" from multiple remotes (either from
a remote group, or "--all") used to make one extra "git fetch" in
the submodules, which has been corrected.
* jc/avoid-redundant-submodule-fetch:
fetch: do not run a redundant fetch from submodule
The "--current" option of "git show-branch" should have been made
incompatible with the "--reflog" mode, but this was not enforced,
which has been corrected.
* jc/show-branch-g-current:
show-branch: -g and --current are incompatible
A bit of test framework fixes with a few fixes to issues found by
valgrind.
* ab/valgrind-fixes:
commit-graph.c: don't assume that stat() succeeds
object-file: fix a unpack_loose_header() regression in 3b6a8db3b0
log test: skip a failing mkstemp() test under valgrind
tests: using custom GIT_EXEC_PATH breaks --valgrind tests
When modifying the sparse-checkout definition, the sparse-checkout
builtin calls update_sparsity() to modify the SKIP_WORKTREE bits of all
cache entries in the index. Before, we needed the index to be fully
expanded in order to ensure we had the full list of files necessary that
match the new patterns.
Insert a call to reset_sparse_directories() that expands sparse
directories that are within the new pattern list, but only far enough
that every necessary file path now exists as a cache entry. The
remaining logic within update_sparsity() will modify the SKIP_WORKTREE
bits appropriately.
This allows us to disable command_requires_full_index within the
sparse-checkout builtin. Add tests that demonstrate that we are not
expanding to a full index unnecessarily.
We can see the improved performance in the p2000 test script:
Test HEAD~1 HEAD
------------------------------------------------------------------------
2000.24: git ... (sparse-v3) 2.14(1.55+0.58) 1.57(1.03+0.53) -26.6%
2000.25: git ... (sparse-v4) 2.20(1.62+0.57) 1.58(0.98+0.59) -28.2%
These reductions of 26-28% are small compared to most examples, but the
time is dominated by writing a new copy of the base repository to the
worktree and then deleting it again. The fact that the previous index
expansion was such a large portion of the time is telling how important
it is to complete this sparse index integration.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The sparse-checkout builtin is almost completely integrated with the
sparse index, allowing the sparse-checkout boundary to be modified
without expanding a sparse index to a full one. Add a test to
p2000-sparse-operations.sh that adds a directory to the sparse-checkout
definition, then removes it. Using both operations is important to
ensure that the operation is doing the same work in each repetition as
well as leaving the test repo in a good state for later tests.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The 'sparse-index contents' test checks that the sparse index has the
correct set of sparse directories in the index after modifying the cone
mode patterns using 'git sparse-checkout set'. Add to the coverage here
by adding more complicated scenarios that were not previously tested.
In order to check paths that do not exist at HEAD, we need to modify the
test_sparse_checkout_set helper slightly:
1. Add the --skip-checks argument to the 'set' command to avoid failures
when passing paths that do not exist at HEAD.
2. When looking for the non-existence of sparse directories for the
paths in $CONE_DIRS, allow the rev-list command to fail because the
path does not exist at HEAD.
This allows us to add some interesting test cases.
Helped-by: Victoria Dye <vdye@github.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Before expanding this test with more involved cases, first extract the
repeated logic into a new test_sparse_checkout_set helper. This helper
checks that 'git sparse-checkout set ...' succeeds and then verifies
that certain directories have sparse directory entries in the sparse
index. It also verifies that the in-cone directories are _not_ sparse
directory entries in the sparse index.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git show :<path>" learned to work better with the sparse-index
feature.
* ds/sparse-colon-path:
rev-parse: integrate with sparse index
object-name: diagnose trees in index properly
object-name: reject trees found in the index
show: integrate with the sparse index
t1092: add compatibility tests for 'git show'
Teach "git stash" to work better with sparse index entries.
* vd/sparse-stash:
unpack-trees: preserve index sparsity
stash: apply stash using 'merge_ort_nonrecursive()'
read-cache: set sparsity when index is new
sparse-index: expose 'is_sparse_index_allowed()'
stash: integrate with sparse index
stash: expand sparse-checkout compatibility testing
"git bisect" was too silent before it is ready to start computing
the actual bisection, which has been corrected.
* cd/bisect-messages-from-pre-flight-states:
bisect: output bisect setup status in bisect log
bisect: output state before we are ready to compute bisection
"git pull" without "--recurse-submodules=<arg>" made
submodule.recurse take precedence over fetch.recurseSubmodules by
mistake, which has been corrected.
* gc/pull-recurse-submodules:
pull: do not let submodule.recurse override fetch.recurseSubmodules
"git log --since=X" will stop traversal upon seeing a commit that
is older than X, but there may be commits behind it that is younger
than X when the commit was created with a faulty clock. A new
option is added to keep digging without stopping, and instead
filter out commits with timestamp older than X.
* mv/log-since-as-filter:
log: "--since-as-filter" option is a non-terminating "--since" variant
The temporary files fed to external diff command are now generated
inside a new temporary directory under the same basename.
* rs/external-diff-tempfile:
diff: use mks_tempfile_dt()
tempfile: add mks_tempfile_dt()
New tests for the safe.directory mechanism.
* sg/safe-directory-tests-and-docs:
safe.directory: document and check that it's ignored in the environment
t0033-safe-directory: check when 'safe.directory' is ignored
t0033-safe-directory: check the error message without matching the trash dir
The previous patch demonstrates a scenario where the list of packs
written by `pack-objects` (and stored in the `names` string_list) is
out-of-order, and can thus cause us to delete packs we shouldn't.
This patch resolves that bug by ensuring that `names` is sorted in all
cases, not just when
delete_redundant && pack_everything & ALL_INTO_ONE
is true.
Because we did sort `names` in that case (which, prior to `--geometric`
repacks, was the only time we would actually delete packs, this is only
a bug for `--geometric` repacks.
It would be sufficient to only sort `names` when `delete_redundant` is
set to a non-zero value. But sorting a small list of strings is cheap,
and it is defensive against future calls to `string_list_has_string()`
on this list.
Co-discovered-by: Victoria Dye <vdye@github.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When doing a `--geometric=<d>` repack, `git repack` determines a
splitting point among packs ordered by their object count such that:
- each pack above the split has at least `<d>` times as many objects
as the next-largest pack by object count, and
- the first pack above the split has at least `<d>` times as many
object as the sum of all packs below the split line combined
`git repack` then creates a pack containing all of the objects contained
in packs below the split line by running `git pack-objects
--stdin-packs` underneath. Once packs are moved into place, then any
packs below the split line are removed, since their objects were just
combined into a new pack.
But `git repack` tries to be careful to avoid removing a pack that it
just wrote, by checking:
struct packed_git *p = geometry->pack[i];
if (string_list_has_string(&names, hash_to_hex(p->hash)))
continue;
in the `delete_redundant` and `geometric` conditional towards the end of
`cmd_repack`.
But it's possible to trick `git repack` into not recognizing a pack that
it just wrote when `names` is out-of-order (which violates
`string_list_has_string()`'s assumption that the list is sorted and thus
binary search-able).
When this happens in just the right circumstances, it is possible to
remove a pack that we just wrote, leading to object corruption.
Luckily, this is quite difficult to provoke in practice (for a couple of
reasons):
- we ordinarily write just one pack, so `names` usually contains just
one entry, and is thus sorted
- when we do write more than one pack (e.g., due to `--max-pack-size`)
we have to: (a) write a pack identical to one that already
exists, (b) have that pack be below the split line, and (c) have
the set of packs written by `pack-objects` occur in an order which
tricks `string_list_has_string()`.
Demonstrate the above scenario in a failing test, which causes `git
repack --geometric` to write a pack which occurs below the split line,
_and_ fail to recognize that it wrote that pack.
The following patch will fix this bug.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Update 'repack' to ignore packs named on the command line with the
'--keep-pack' option. Specifically, modify 'init_pack_geometry()' to treat
command line-kept packs the same way it treats packs with an on-disk '.keep'
file (that is, skip the pack and do not include it in the 'geometry'
structure).
Without this handling, a '--keep-pack' pack would be included in the
'geometry' structure. If the pack is *before* the geometry split line (with
at least one other pack and/or loose objects present), 'repack' assumes the
pack's contents are "rolled up" into another pack via 'pack-objects'.
However, because the internally-invoked 'pack-objects' properly excludes
'--keep-pack' objects, any new pack it creates will not contain the kept
objects. Finally, 'repack' deletes the '--keep-pack' as "redundant" (since
it assumes 'pack-objects' created a new pack with its contents), resulting
in possible object loss and repository corruption.
Add a test ensuring that '--keep-pack' packs are now appropriately handled.
Co-authored-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We do make sure that an attempt to merge with various forms of local
changes will "fail", but the point of stopping the merge is so that
we refrain from discarding uncommitted local changes that could be
precious. Add a few more checks for each case to make sure the
local changes are left intact.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When 7dce19d3 (fetch/pull: Add the --recurse-submodules option,
2010-11-12) introduced the "--recurse-submodule" option, the
approach taken was to perform fetches in submodules only once, after
all the main fetching (it may usually be a fetch from a single
remote, but it could be fetching from a group of remotes using
fetch_multiple()) succeeded. Later we added "--all" to fetch from
all defined remotes, which complicated things even more.
If your project has a submodule, and you try to run "git fetch
--recurse-submodule --all", you'd see a fetch for the top-level,
which invokes another fetch for the submodule, followed by another
fetch for the same submodule. All but the last fetch for the
submodule come from a "git fetch --recurse-submodules" subprocess
that is spawned via the fetch_multiple() interface for the remotes,
and the last fetch comes from the code at the end.
Because recursive fetching from submodules is done in each fetch for
the top-level in fetch_multiple(), the last fetch in the submodule
is redundant. It only matters when fetch_one() interacts with a
single remote at the top-level.
While we are at it, there is one optimization that exists in dealing
with a group of remote, but is missing when "--all" is used. In the
former, when the group turns out to be a group of one, instead of
spawning "git fetch" as a subprocess via the fetch_multiple()
interface, we use the normal fetch_one() code path. Do the same
when handing "--all", if it turns out that we have only one remote
defined.
Reviewed-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
