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The pop_most_recent_commit() function can have quite expensive
worst case performance characteristics, which has been optimized by
using prio-queue data structure.
* rs/pop-recent-commit-with-prio-queue:
commit: use prio_queue_replace() in pop_most_recent_commit()
prio-queue: add prio_queue_replace()
commit: convert pop_most_recent_commit() to prio_queue
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Optimize pop_most_recent_commit() by adding the first parent using the
more efficient prio_queue_peek() and prio_queue_replace() instead of
prio_queue_get() and prio_queue_put().
On my machine this neutralizes the performance hit it took in Git's own
repository when we converted it to prio_queue two patches ago (git_pq):
$ hyperfine -w3 -L git ./git_2.50.1,./git_pq,./git '{git} rev-parse :/^Initial.revision'
Benchmark 1: ./git_2.50.1 rev-parse :/^Initial.revision
Time (mean ± σ): 1.073 s ± 0.003 s [User: 1.053 s, System: 0.019 s]
Range (min … max): 1.069 s … 1.078 s 10 runs
Benchmark 2: ./git_pq rev-parse :/^Initial.revision
Time (mean ± σ): 1.077 s ± 0.002 s [User: 1.057 s, System: 0.018 s]
Range (min … max): 1.072 s … 1.079 s 10 runs
Benchmark 3: ./git rev-parse :/^Initial.revision
Time (mean ± σ): 1.069 s ± 0.003 s [User: 1.049 s, System: 0.018 s]
Range (min … max): 1.065 s … 1.074 s 10 runs
Summary
./git rev-parse :/^Initial.revision ran
1.00 ± 0.00 times faster than ./git_2.50.1 rev-parse :/^Initial.revision
1.01 ± 0.00 times faster than ./git_pq rev-parse :/^Initial.revision
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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pop_most_recent_commit() calls commit_list_insert_by_date() for parent
commits, which is itself called in a loop. This can lead to quadratic
complexity if there are many merges. Replace the commit_list with a
prio_queue to ensure logarithmic worst case complexity and convert all
three users.
Add a performance test that exercises one of them using a pathological
history that consists of 50% merges and 50% root commits to demonstrate
the speedup:
Test v2.50.1 HEAD
----------------------------------------------------------------------
1501.2: rev-parse ':/65535' 2.48(2.47+0.00) 0.20(0.19+0.00) -91.9%
Alas, sane histories don't benefit from the conversion much, and
traversing Git's own history takes a 1% performance hit on my machine:
$ hyperfine -w3 -L git ./git_2.50.1,./git '{git} rev-parse :/^Initial.revision'
Benchmark 1: ./git_2.50.1 rev-parse :/^Initial.revision
Time (mean ± σ): 1.071 s ± 0.004 s [User: 1.052 s, System: 0.017 s]
Range (min … max): 1.067 s … 1.078 s 10 runs
Benchmark 2: ./git rev-parse :/^Initial.revision
Time (mean ± σ): 1.079 s ± 0.003 s [User: 1.060 s, System: 0.017 s]
Range (min … max): 1.074 s … 1.083 s 10 runs
Summary
./git_2.50.1 rev-parse :/^Initial.revision ran
1.01 ± 0.00 times faster than ./git rev-parse :/^Initial.revision
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Rename `has_object()` to `odb_has_object()` to match other functions
related to the object database and our modern coding guidelines.
Introduce a compatibility wrapper so that any in-flight topics will
continue to compile.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Rename `repo_read_object_file()` to `odb_read_object()` to match other
functions related to the object database and our modern coding
guidelines.
Introduce a compatibility wrapper so that any in-flight topics will
continue to compile.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Rename `oid_object_info()` to `odb_read_object_info()` as well as their
`_extended()` variant to match other functions related to the object
database and our modern coding guidelines.
Introduce compatibility wrappers so that any in-flight topics will
continue to compile.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Get rid of our dependency on `the_repository` in `assert_oid_type()` by
passing in the object database as a parameter and adjusting all callers.
Rename the function to `odb_assert_oid_type()`.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In the preceding commits we have renamed the structures contained in
"object-store.h" to `struct object_database` and `struct odb_backend`.
As such, the code files "object-store.{c,h}" are confusingly named now.
Rename them to "odb.{c,h}" accordingly.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Code clean-up.
* ps/object-file-cleanup:
object-store: merge "object-store-ll.h" and "object-store.h"
object-store: remove global array of cached objects
object: split out functions relating to object store subsystem
object-file: drop `index_blob_stream()`
object-file: split up concerns of `HASH_*` flags
object-file: split out functions relating to object store subsystem
object-file: move `xmmap()` into "wrapper.c"
object-file: move `git_open_cloexec()` to "compat/open.c"
object-file: move `safe_create_leading_directories()` into "path.c"
object-file: move `mkdir_in_gitdir()` into "path.c"
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The object layer has been updated to take an explicit repository
instance as a parameter in more code paths.
* ps/object-wo-the-repository:
hash: stop depending on `the_repository` in `null_oid()`
hash: fix "-Wsign-compare" warnings
object-file: split out logic regarding hash algorithms
delta-islands: stop depending on `the_repository`
object-file-convert: stop depending on `the_repository`
pack-bitmap-write: stop depending on `the_repository`
pack-revindex: stop depending on `the_repository`
pack-check: stop depending on `the_repository`
environment: move access to "core.bigFileThreshold" into repo settings
pack-write: stop depending on `the_repository` and `the_hash_algo`
object: stop depending on `the_repository`
csum-file: stop depending on `the_repository`
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The "object-store-ll.h" header has been introduced to keep transitive
header dependendcies and compile times at bay. Now that we have created
a new "object-store.c" file though we can easily move the last remaining
additional bit of "object-store.h", the `odb_path_map`, out of the
header.
Do so. As the "object-store.h" header is now equivalent to its low-level
alternative we drop the latter and inline it into the former.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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While we have the "object-store.h" header, most of the functionality for
object stores is actually hosted in "object-file.c". This makes it hard
to find relevant functions and causes us to mix up concerns.
Split out functions relating to the object store subsystem into a new
"object-store.c" file.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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clear_commit_marks_many() clears multiple commits one by one. Move the
code for handling a single commit to clear_commit_marks() and call it
instead of the other way around, to simplify the code.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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There are multiple sites in "object-file-convert.c" where we use the
global `the_repository` variable, either explicitly or implicitly by
using `the_hash_algo`. All of these callsites are transitively called
from `convert_object_file()`, which indeed has no repo as input.
Refactor the function so that it receives a repository as a parameter
and pass it through to all internal functions to get rid of the
dependency. Remove the `USE_THE_REPOSITORY_VARIABLE` define.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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clear_commit_marks_1() clears the marks of the first parent and its
first parent and so on, and saves the higher numbered parents in a list
for later. There is no benefit in keeping that list growing with each
handled commit. Clear it after each run to reduce peak memory usage.
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Similar as with the preceding commit, adapt `get_reachable_subset()` so
that it tracks array indices via `size_t` instead of using signed
integers to fix a couple of -Wsign-compare warnings. Adapt callers
accordingly.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Start working to make the codebase buildable with -Wsign-compare.
* ps/build-sign-compare:
t/helper: don't depend on implicit wraparound
scalar: address -Wsign-compare warnings
builtin/patch-id: fix type of `get_one_patchid()`
builtin/blame: fix type of `length` variable when emitting object ID
gpg-interface: address -Wsign-comparison warnings
daemon: fix type of `max_connections`
daemon: fix loops that have mismatching integer types
global: trivial conversions to fix `-Wsign-compare` warnings
pkt-line: fix -Wsign-compare warning on 32 bit platform
csum-file: fix -Wsign-compare warning on 32-bit platform
diff.h: fix index used to loop through unsigned integer
config.mak.dev: drop `-Wno-sign-compare`
global: mark code units that generate warnings with `-Wsign-compare`
compat/win32: fix -Wsign-compare warning in "wWinMain()"
compat/regex: explicitly ignore "-Wsign-compare" warnings
git-compat-util: introduce macros to disable "-Wsign-compare" warnings
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The advice messages now tell the newer 'git config set' command to
set the advice.token configuration variable to squelch a message.
* bf/explicit-config-set-in-advice-messages:
advice: suggest using subcommand "git config set"
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We have a bunch of loops which iterate up to an unsigned boundary using
a signed index, which generates warnigs because we compare a signed and
unsigned value in the loop condition. Address these sites for trivial
cases and enable `-Wsign-compare` warnings for these code units.
This patch only adapts those code units where we can drop the
`DISABLE_SIGN_COMPARE_WARNINGS` macro in the same step.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Mark code units that generate warnings with `-Wsign-compare`. This
allows for a structured approach to get rid of all such warnings over
time in a way that can be easily measured.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The advice message currently suggests using "git config advice..." to
disable advice messages, but since
00bbdde141 (builtin/config: introduce "set" subcommand, 2024-05-06)
we have the "set" subcommand for config. Since using the subcommand is
more in-line with the modern interface, any advice should be promoting
its usage. Change the disable advice message to use the subcommand
instead. Change all uses of "git config advice" in the tests to use the
subcommand.
Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When we parse a commit via repo_parse_commit_internal(), if
save_commit_buffer is set we'll stuff the buffer of the object contents
into a cache, overwriting any previous value.
This can result in a leak of that previously cached value, though it's
rare in practice. If we have a value in the cache it would have come
from a previous parse, and during that parse we'd set the object.parsed
flag, causing any subsequent parse attempts to exit without doing any
work.
But it's possible to "unparse" a commit, which we do when registering a
commit graft. And since shallow fetches are implemented using grafts,
the leak is triggered in practice by t5539.
There are a number of possible ways to address this:
1. the unparsing function could clear the cached commit buffer, too. I
think this would work for the case I found, but I'm not sure if
there are other ways to end up in the same state (an unparsed
commit with an entry in the commit buffer cache).
2. when we parse, we could check the buffer cache and prefer it to
reading the contents from the object database. In theory the
contents of a particular sha1 are immutable, but the code in
question is violating the immutability with grafts. So this
approach makes me a bit nervous, although I think it would work in
practice (the grafts are applied to what we parse, but we still
retain the original contents).
3. We could realize the cache is already populated and discard its
contents before overwriting. It's possible some other code could be
holding on to a pointer to the old cache entry (and we'd introduce
a use-after-free), but I think the risk of that is relatively low.
4. The reverse of (3): when the cache is populated, don't bother
saving our new copy. This is perhaps a little weird, since we'll
have just populated the commit struct based on a different buffer.
But the two buffers should be the same, even in the presence of
grafts (as in (2) above).
I went with option 4. It addresses the leak directly and doesn't carry
any risk of breaking other assumptions. And it's the same technique used
by parse_object_buffer() for this situation, though I'm not sure when it
would even come up there. The extra safety has been there since
bd1e17e245 (Make "parse_object()" also fill in commit message buffer
data., 2005-05-25).
This lets us mark t5539 as leak-free.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Code clean-up.
* ps/environ-wo-the-repository: (21 commits)
environment: stop storing "core.notesRef" globally
environment: stop storing "core.warnAmbiguousRefs" globally
environment: stop storing "core.preferSymlinkRefs" globally
environment: stop storing "core.logAllRefUpdates" globally
refs: stop modifying global `log_all_ref_updates` variable
branch: stop modifying `log_all_ref_updates` variable
repo-settings: track defaults close to `struct repo_settings`
repo-settings: split out declarations into a standalone header
environment: guard state depending on a repository
environment: reorder header to split out `the_repository`-free section
environment: move `set_git_dir()` and related into setup layer
environment: make `get_git_namespace()` self-contained
environment: move object database functions into object layer
config: make dependency on repo in `read_early_config()` explicit
config: document `read_early_config()` and `read_very_early_config()`
environment: make `get_git_work_tree()` accept a repository
environment: make `get_graft_file()` accept a repository
environment: make `get_index_file()` accept a repository
environment: make `get_object_directory()` accept a repository
environment: make `get_git_common_dir()` accept a repository
...
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More leakfixes.
* ps/leakfixes-part-6: (22 commits)
builtin/repack: fix leaking keep-pack list
merge-ort: fix two leaks when handling directory rename modifications
match-trees: fix leaking prefixes in `shift_tree()`
builtin/fmt-merge-msg: fix leaking buffers
builtin/grep: fix leaking object context
builtin/pack-objects: plug leaking list of keep-packs
builtin/repack: fix leaking line buffer when packing promisors
negotiator/skipping: fix leaking commit entries
shallow: fix leaking members of `struct shallow_info`
shallow: free grafts when unregistering them
object: clear grafts when clearing parsed object pool
gpg-interface: fix misdesigned signing key interfaces
send-pack: fix leaking push cert nonce
remote: fix leak in reachability check of a remote-tracking ref
remote: fix leaking tracking refs
builtin/submodule--helper: fix leaking refs on push-check
submodule: fix leaking fetch task data
upload-pack: fix leaking child process data on reachability checks
builtin/push: fix leaking refspec query result
send-pack: fix leaking common object IDs
...
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The `get_graft_file()` function retrieves the path to the graft file of
`the_repository`. Make it accept a `struct repository` such that it can
work on arbitrary repositories and make it part of the repository
subsystem. This reduces our reliance on `the_repository` and clarifies
scope.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We do not clear grafts part of the parsed object pool when clearing the
pool itself, which can lead to memory leaks when a repository is being
cleared.
Fix this by moving `reset_commit_grafts()` into "object.c" and making it
part of the `struct parsed_object_pool` interface such that we can call
it from `parsed_object_pool_clear()`. Adapt `parsed_object_pool_new()`
to take and store a reference to its owning repository, which is needed
by `unparse_commit()`.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The interfaces to retrieve signing keys and their IDs are misdesigned as
they return string constants even though they indeed allocate memory,
which leads to memory leaks. Refactor the code to instead always return
allocated strings and let the callers free them accordingly.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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'git for-each-ref' learned a new "--format" atom to find the branch
that the history leading to a given commit "%(is-base:<commit>)" is
likely based on.
* ds/for-each-ref-is-base:
p1500: add is-base performance tests
for-each-ref: add 'is-base' token
commit: add gentle reference lookup method
commit-reach: add get_branch_base_for_tip
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The lookup_commit_reference_by_name() method uses lookup_commit_reference()
without an option to use lookup_commit_reference_gently(). Create a gentle
version of the method so it can be used in locations where non-commits may
be found but error messages should be silenced.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We implicitly depend on `the_repository` in our hook subsystem because
we use `strbuf_git_path()` to compute hook paths. Remove this dependency
by accepting a `struct repository` as parameter instead.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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More memory leaks have been plugged.
* ps/leakfixes-more: (29 commits)
builtin/blame: fix leaking ignore revs files
builtin/blame: fix leaking prefixed paths
blame: fix leaking data for blame scoreboards
line-range: plug leaking find functions
merge: fix leaking merge bases
builtin/merge: fix leaking `struct cmdnames` in `get_strategy()`
sequencer: fix memory leaks in `make_script_with_merges()`
builtin/clone: plug leaking HEAD ref in `wanted_peer_refs()`
apply: fix leaking string in `match_fragment()`
sequencer: fix leaking string buffer in `commit_staged_changes()`
commit: fix leaking parents when calling `commit_tree_extended()`
config: fix leaking "core.notesref" variable
rerere: fix various trivial leaks
builtin/stash: fix leak in `show_stash()`
revision: free diff options
builtin/log: fix leaking commit list in git-cherry(1)
merge-recursive: fix memory leak when finalizing merge
builtin/merge-recursive: fix leaking object ID bases
builtin/difftool: plug memory leaks in `run_dir_diff()`
object-name: free leaking object contexts
...
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A CPP macro USE_THE_REPOSITORY_VARIABLE is introduced to help
transition the codebase to rely less on the availability of the
singleton the_repository instance.
* ps/use-the-repository:
hex: guard declarations with `USE_THE_REPOSITORY_VARIABLE`
t/helper: remove dependency on `the_repository` in "proc-receive"
t/helper: fix segfault in "oid-array" command without repository
t/helper: use correct object hash in partial-clone helper
compat/fsmonitor: fix socket path in networked SHA256 repos
replace-object: use hash algorithm from passed-in repository
protocol-caps: use hash algorithm from passed-in repository
oidset: pass hash algorithm when parsing file
http-fetch: don't crash when parsing packfile without a repo
hash-ll: merge with "hash.h"
refs: avoid include cycle with "repository.h"
global: introduce `USE_THE_REPOSITORY_VARIABLE` macro
hash: require hash algorithm in `empty_tree_oid_hex()`
hash: require hash algorithm in `is_empty_{blob,tree}_oid()`
hash: make `is_null_oid()` independent of `the_repository`
hash: convert `oidcmp()` and `oideq()` to compare whole hash
global: ensure that object IDs are always padded
hash: require hash algorithm in `oidread()` and `oidclr()`
hash: require hash algorithm in `hasheq()`, `hashcmp()` and `hashclr()`
hash: drop (mostly) unused `is_empty_{blob,tree}_sha1()` functions
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Code clean-up.
* rs/remove-unused-find-header-mem:
commit: remove find_header_mem()
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cfc5cf428b (receive-pack.c: consolidate find header logic, 2022-01-06)
introduced find_header_mem() and turned find_commit_header() into a thin
wrapper. Since then, the latter has become the last remaining caller of
the former. Remove it to restore find_commit_header() to the state
before cfc5cf428b, get rid of a strlen(3) call and resolve a NEEDSWORK
note in the process.
Signed-off-by: René Scharfe <l.s.r@web.de>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Use of the `the_repository` variable is deprecated nowadays, and we
slowly but steadily convert the codebase to not use it anymore. Instead,
callers should be passing down the repository to work on via parameters.
It is hard though to prove that a given code unit does not use this
variable anymore. The most trivial case, merely demonstrating that there
is no direct use of `the_repository`, is already a bit of a pain during
code reviews as the reviewer needs to manually verify claims made by the
patch author. The bigger problem though is that we have many interfaces
that implicitly rely on `the_repository`.
Introduce a new `USE_THE_REPOSITORY_VARIABLE` macro that allows code
units to opt into usage of `the_repository`. The intent of this macro is
to demonstrate that a certain code unit does not use this variable
anymore, and to keep it from new dependencies on it in future changes,
be it explicit or implicit
For now, the macro only guards `the_repository` itself as well as
`the_hash_algo`. There are many more known interfaces where we have an
implicit dependency on `the_repository`, but those are not guarded at
the current point in time. Over time though, we should start to add
guards as required (or even better, just remove them).
Define the macro as required in our code units. As expected, most of our
code still relies on the global variable. Nearly all of our builtins
rely on the variable as there is no way yet to pass `the_repository` to
their entry point. For now, declare the macro in "biultin.h" to keep the
required changes at least a little bit more contained.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When calling either the recursive or the ORT merge machineries we need
to provide a list of merge bases. The ownership of that parameter is
then implicitly transferred to the callee, which is somewhat fishy.
Furthermore, that list may leak in some cases where the merge machinery
runs into an error, thus causing a memory leak.
Refactor the code such that we stop transferring ownership. Instead, the
merge machinery will now create its own local copies of the passed in
list as required if they need to modify the list. Free the list at the
callsites as required.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When creating commits via `commit_tree_extended()`, the caller passes in
a string list of parents. This call implicitly transfers ownership of
that list to the function, which is quite surprising to begin with. But
to make matters worse, `commit_tree_extended()` doesn't even bother to
free the list of parents in error cases. The result is a memory leak,
and one that the caller cannot fix by themselves because they do not
know whether parts of the string list have already been released.
Refactor the code such that callers can keep ownership of the list of
parents, which is getting indicated by parameter being a constant
pointer now. Free the lists at the calling site and add a common exit
path to those sites as required.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Apply the rules that rewrite callers of "refs" interfaces to explicitly
pass `struct ref_store`. The resulting patch has been applied with the
`--whitespace=fix` option.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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core.commentChar used to be limited to a single byte, but has been
updated to allow an arbitrary multi-byte sequence.
* jk/core-comment-string:
config: add core.commentString
config: allow multi-byte core.commentChar
environment: drop comment_line_char compatibility macro
wt-status: drop custom comment-char stringification
sequencer: handle multi-byte comment characters when writing todo list
find multi-byte comment chars in unterminated buffers
find multi-byte comment chars in NUL-terminated strings
prefer comment_line_str to comment_line_char for printing
strbuf: accept a comment string for strbuf_add_commented_lines()
strbuf: accept a comment string for strbuf_commented_addf()
strbuf: accept a comment string for strbuf_stripspace()
environment: store comment_line_char as a string
strbuf: avoid shadowing global comment_line_char name
commit: refactor base-case of adjust_comment_line_char()
strbuf: avoid static variables in strbuf_add_commented_lines()
strbuf: simplify comment-handling in add_lines() helper
config: forbid newline as core.commentChar
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Work to support a repository that work with both SHA-1 and SHA-256
hash algorithms has started.
* eb/hash-transition: (30 commits)
t1016-compatObjectFormat: add tests to verify the conversion between objects
t1006: test oid compatibility with cat-file
t1006: rename sha1 to oid
test-lib: compute the compatibility hash so tests may use it
builtin/ls-tree: let the oid determine the output algorithm
object-file: handle compat objects in check_object_signature
tree-walk: init_tree_desc take an oid to get the hash algorithm
builtin/cat-file: let the oid determine the output algorithm
rev-parse: add an --output-object-format parameter
repository: implement extensions.compatObjectFormat
object-file: update object_info_extended to reencode objects
object-file-convert: convert commits that embed signed tags
object-file-convert: convert commit objects when writing
object-file-convert: don't leak when converting tag objects
object-file-convert: convert tag objects when writing
object-file-convert: add a function to convert trees between algorithms
object: factor out parse_mode out of fast-import and tree-walk into in object.h
cache: add a function to read an OID of a specific algorithm
tag: sign both hashes
commit: export add_header_signature to support handling signatures on tags
...
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As with the previous patch, we need to swap out single-byte matching for
something like starts_with() to match all bytes of a multi-byte comment
character. But for cases where the buffer is not NUL-terminated (and we
instead have an explicit size or end pointer), it's not safe to use
starts_with(), as it might walk off the end of the buffer.
Let's introduce a new starts_with_mem() that does the same thing but
also accepts the length of the "haystack" str and makes sure not to walk
past it.
Note that in most cases the existing code did not need a length check at
all, since it was written in a way that knew we had at least one byte
available (and that was all we checked). So I had to read each one to
find the appropriate bounds. The one exception is sequencer.c's
add_commented_lines(), where we can actually get rid of the length
check. Just like starts_with(), our starts_with_mem() handles an empty
haystack variable by not matching (assuming a non-empty prefix).
A few notes on the implementation of starts_with_mem():
- it would be equally correct to take an "end" pointer (and indeed,
many of the callers have this and have to subtract to come up with
the length). I think taking a ptr/size combo is a more usual
interface for our codebase, though, and has the added benefit that
the function signature makes it harder to mix up the three
parameters.
- we could obviously build starts_with() on top of this by passing
strlen(str) as the length. But it's possible that starts_with() is a
relatively hot code path, and it should not pay that penalty (it can
generally return an answer proportional to the size of the prefix,
not the whole string).
- it naively feels like xstrncmpz() should be able to do the same
thing, but that's not quite true. If you pass the length of the
haystack buffer, then strncmp() finds that a shorter prefix string
is "less than" than the haystack, even if the haystack starts with
the prefix. If you pass the length of the prefix, then you risk
reading past the end of the haystack if it is shorter than the
prefix. So I think we really do need a new function.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The `merge_bases_many()` function was just taught to indicate parsing
errors, and now the `repo_get_merge_bases_many()` function is aware of
that, too.
Naturally, there are a lot of callers that need to be adjusted now, too.
Next stop: `repo_get_merge_bases_dirty()`.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Remove unused header "#include".
* en/header-cleanup:
treewide: remove unnecessary includes in source files
treewide: add direct includes currently only pulled in transitively
trace2/tr2_tls.h: remove unnecessary include
submodule-config.h: remove unnecessary include
pkt-line.h: remove unnecessary include
line-log.h: remove unnecessary include
http.h: remove unnecessary include
fsmonitor--daemon.h: remove unnecessary includes
blame.h: remove unnecessary includes
archive.h: remove unnecessary include
treewide: remove unnecessary includes in source files
treewide: remove unnecessary includes from header files
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Code clean-up.
* la/trailer-cleanups:
trailer: use offsets for trailer_start/trailer_end
trailer: find the end of the log message
commit: ignore_non_trailer computes number of bytes to ignore
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Remove unused header "#include".
* en/header-cleanup:
treewide: remove unnecessary includes in source files
treewide: add direct includes currently only pulled in transitively
trace2/tr2_tls.h: remove unnecessary include
submodule-config.h: remove unnecessary include
pkt-line.h: remove unnecessary include
line-log.h: remove unnecessary include
http.h: remove unnecessary include
fsmonitor--daemon.h: remove unnecessary includes
blame.h: remove unnecessary includes
archive.h: remove unnecessary include
treewide: remove unnecessary includes in source files
treewide: remove unnecessary includes from header files
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Code clean-up.
* la/trailer-cleanups:
trailer: use offsets for trailer_start/trailer_end
trailer: find the end of the log message
commit: ignore_non_trailer computes number of bytes to ignore
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Each of these were checked with
gcc -E -I. ${SOURCE_FILE} | grep ${HEADER_FILE}
to ensure that removing the direct inclusion of the header actually
resulted in that header no longer being included at all (i.e. that
no other header pulled it in transitively).
...except for a few cases where we verified that although the header
was brought in transitively, nothing from it was directly used in
that source file. These cases were:
* builtin/credential-cache.c
* builtin/pull.c
* builtin/send-pack.c
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In 7a5d604443 (commit: detect commits that exist in commit-graph but not
in the ODB, 2023-10-31), we have introduced a new object existence check
into `repo_parse_commit_internal()` so that we do not parse commits via
the commit-graph that don't have a corresponding object in the object
database. This new check of course comes with a performance penalty,
which the commit put at around 30% for `git rev-list --topo-order`. But
there are in fact scenarios where the performance regression is even
higher. The following benchmark against linux.git with a fully-build
commit-graph:
Benchmark 1: git.v2.42.1 rev-list --count HEAD
Time (mean ± σ): 658.0 ms ± 5.2 ms [User: 613.5 ms, System: 44.4 ms]
Range (min … max): 650.2 ms … 666.0 ms 10 runs
Benchmark 2: git.v2.43.0-rc1 rev-list --count HEAD
Time (mean ± σ): 1.333 s ± 0.019 s [User: 1.263 s, System: 0.069 s]
Range (min … max): 1.302 s … 1.361 s 10 runs
Summary
git.v2.42.1 rev-list --count HEAD ran
2.03 ± 0.03 times faster than git.v2.43.0-rc1 rev-list --count HEAD
While it's a noble goal to ensure that results are the same regardless
of whether or not we have a potentially stale commit-graph, taking twice
as much time is a tough sell. Furthermore, we can generally assume that
the commit-graph will be updated by git-gc(1) or git-maintenance(1) as
required so that the case where the commit-graph is stale should not at
all be common.
With that in mind, default-disable GIT_COMMIT_GRAPH_PARANOIA and restore
the behaviour and thus performance previous to the mentioned commit. In
order to not be inconsistent, also disable this behaviour by default in
`lookup_commit_in_graph()`, where the object existence check has been
introduced right at its inception via f559d6d45e (revision: avoid
hitting packfiles when commits are in commit-graph, 2021-08-09).
This results in another speedup in commands that end up calling this
function, even though it's less pronounced compared to the above
benchmark. The following has been executed in linux.git with ~1.2
million references:
Benchmark 1: GIT_COMMIT_GRAPH_PARANOIA=true git rev-list --all --no-walk=unsorted
Time (mean ± σ): 2.947 s ± 0.003 s [User: 2.412 s, System: 0.534 s]
Range (min … max): 2.943 s … 2.949 s 3 runs
Benchmark 2: GIT_COMMIT_GRAPH_PARANOIA=false git rev-list --all --no-walk=unsorted
Time (mean ± σ): 2.724 s ± 0.030 s [User: 2.207 s, System: 0.514 s]
Range (min … max): 2.704 s … 2.759 s 3 runs
Summary
GIT_COMMIT_GRAPH_PARANOIA=false git rev-list --all --no-walk=unsorted ran
1.08 ± 0.01 times faster than GIT_COMMIT_GRAPH_PARANOIA=true git rev-list --all --no-walk=unsorted
So whereas 7a5d604443 initially introduced the logic to start doing an
object existence check in `repo_parse_commit_internal()` by default, the
updated logic will now instead cause `lookup_commit_in_graph()` to stop
doing the check by default. This behaviour continues to be tweakable by
the user via the GIT_COMMIT_GRAPH_PARANOIA environment variable.
Note that this requires us to amend some tests to manually turn on the
paranoid checks again. This is because we cause repository corruption by
manually deleting objects which are part of the commit graph already.
These circumstances shouldn't usually happen in repositories.
Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Commit graphs can become stale and contain references to commits that do
not exist in the object database anymore. Theoretically, this can lead
to a scenario where we are able to successfully look up any such commit
via the commit graph even though such a lookup would fail if done via
the object database directly.
As the commit graph is mostly intended as a sort of cache to speed up
parsing of commits we do not want to have diverging behaviour in a
repository with and a repository without commit graphs, no matter
whether they are stale or not. As commits are otherwise immutable, the
only thing that we really need to care about is thus the presence or
absence of a commit.
To address potentially stale commit data that may exist in the graph,
our `lookup_commit_in_graph()` function will check for the commit's
existence in both the commit graph, but also in the object database. So
even if we were able to look up the commit's data in the graph, we would
still pretend as if the commit didn't exist if it is missing in the
object database.
We don't have the same safety net in `parse_commit_in_graph_one()`
though. This function is mostly used internally in "commit-graph.c"
itself to validate the commit graph, and this usage is fine. We do
expose its functionality via `parse_commit_in_graph()` though, which
gets called by `repo_parse_commit_internal()`, and that function is in
turn used in many places in our codebase.
For all I can see this function is never used to directly turn an object
ID into a commit object without additional safety checks before or after
this lookup. What it is being used for though is to walk history via the
parent chain of commits. So when commits in the parent chain of a graph
walk are missing it is possible that we wouldn't notice if that missing
commit was part of the commit graph. Thus, a query like `git rev-parse
HEAD~2` can succeed even if the intermittent commit is missing.
It's unclear whether there are additional ways in which such stale
commit graphs can lead to problems. In any case, it feels like this is a
bigger bug waiting to happen when we gain additional direct or indirect
callers of `repo_parse_commit_internal()`. So let's fix the inconsistent
behaviour by checking for object existence via the object database, as
well.
This check of course comes with a performance penalty. The following
benchmarks have been executed in a clone of linux.git with stable tags
added:
Benchmark 1: git -c core.commitGraph=true rev-list --topo-order --all (git = master)
Time (mean ± σ): 2.913 s ± 0.018 s [User: 2.363 s, System: 0.548 s]
Range (min … max): 2.894 s … 2.950 s 10 runs
Benchmark 2: git -c core.commitGraph=true rev-list --topo-order --all (git = pks-commit-graph-inconsistency)
Time (mean ± σ): 3.834 s ± 0.052 s [User: 3.276 s, System: 0.556 s]
Range (min … max): 3.780 s … 3.961 s 10 runs
Benchmark 3: git -c core.commitGraph=false rev-list --topo-order --all (git = master)
Time (mean ± σ): 13.841 s ± 0.084 s [User: 13.152 s, System: 0.687 s]
Range (min … max): 13.714 s … 13.995 s 10 runs
Benchmark 4: git -c core.commitGraph=false rev-list --topo-order --all (git = pks-commit-graph-inconsistency)
Time (mean ± σ): 13.762 s ± 0.116 s [User: 13.094 s, System: 0.667 s]
Range (min … max): 13.645 s … 14.038 s 10 runs
Summary
git -c core.commitGraph=true rev-list --topo-order --all (git = master) ran
1.32 ± 0.02 times faster than git -c core.commitGraph=true rev-list --topo-order --all (git = pks-commit-graph-inconsistency)
4.72 ± 0.05 times faster than git -c core.commitGraph=false rev-list --topo-order --all (git = pks-commit-graph-inconsistency)
4.75 ± 0.04 times faster than git -c core.commitGraph=false rev-list --topo-order --all (git = master)
We look at a ~30% regression in general, but in general we're still a
whole lot faster than without the commit graph. To counteract this, the
new check can be turned off with the `GIT_COMMIT_GRAPH_PARANOIA` envvar.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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ignore_non_trailer() returns the _number of bytes_ that should be
ignored from the end of the log message. It does not by itself "ignore"
anything.
Rename this function to remove the leading "ignore" verb, to sound more
like a quantity than an action.
Signed-off-by: Linus Arver <linusa@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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