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The --contents option can be used with git blame to blame the file as if
it had the contents from the specified file. This is akin to copying the
contents into the working tree and then running git blame. This option
has been supported since 1cfe77333f27 ("git-blame: no rev means start
from the working tree file.")
The --contents option always blames the file as if it was based on the
current HEAD commit. If you try to pass a revision while using
--contents, you get the following error:
fatal: cannot use --contents with final commit object name
This is because the blame process generates a fake working tree commit
which always uses the HEAD object as its sole parent.
Enhance fake_working_tree_commit to take the object ID to use for the
parent instead of always using the HEAD object. Then, always generate a
fake commit when we have contents provided, even if we have a final
object. Remove the check to disallow --contents and a final revision.
Note that the behavior of generating a fake working commit is still
skipped when a revision is provided but --contents is not provided.
Generating such a commit in that case would combine the currently
checked out file contents with the provided revision, which breaks
normal blame behavior and produces unexpected results.
This enables use of --contents with an arbitrary revision, rather than
forcing the use of the local HEAD commit. This makes the --contents
option significantly more flexible, as it is no longer required to check
out the working tree to the desired commit before using --contents.
Reword the documentation so that its clear that --contents can be used
with <rev>.
Add tests for the --contents option to the annotate-tests.sh test
script.
Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Saves some code duplication.
Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The file is gone even if commit_lock_file() fails.
Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In c3b58472be2 (pack-redundant: gauge the usage before proposing its
removal, 2020-08-25), we added a big, ugly warning when pack-redundant
is run. The plan there indicated that we would ratchet that up to an
error before finally removing it. Since it has been 2.5 years (and 9
releases) since then, let's continue with the plan.
Note that we did get one bite on the warning, which was somebody asking
about alternatives:
https://lore.kernel.org/git/CAKvOHKAFXQwt4D8yUCCkf_TQL79mYaJ=KAKhtpDNTvHJFuX1NA@mail.gmail.com/
but we didn't undo the ugly warning (and the advice continues to be "use
repack -d" instead).
There was also some discussion around the time of the deprecation that
pack-redundant was invoked by the bitbake tool, and it still seems to do
so now:
https://git.openembedded.org/bitbake
That use should probably just go away in favor of an occasional repack
(which probably even happens via auto-gc after fetch these days).
But since neither of those data points caused us to cancel the
deprecation plan by dropping the warning, it seems like we should
proceed with the next step.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Basically git work with default curl ssl type - PEM. But for support
eTokens like SafeNet tokens via pksc11 need setup 'ENG' as sslcert type
and as sslkey type. So there added additional options for http to make
that possible.
Signed-off-by: Stanislav Malishevskiy <stanislav.malishevskiy@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Stephane is reporting[1] a regression introduced in git v2.40.0 that leads
to 'git grep' segfaulting in his CI pipeline. It turns out, he's using an
older version of libpcre2 that triggers a wild pointer dereference in
the generated JIT code that was fixed in PCRE2 10.35.
Instead of completely disabling the JIT compiler for the buggy version,
just mask out the Unicode property handling as we used to do prior to
commit acabd2048ee0 ("grep: correctly identify utf-8 characters with
\{b,w} in -P").
[1] https://lore.kernel.org/git/7E83DAA1-F9A9-4151-8D07-D80EA6D59EEA@clumio.com/
Reported-by: Stephane Odul <stephane@clumio.com>
Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Cherry pick commit d3775de0 (Makefile: force -O0 when compiling with
SANITIZE=leak, 2022-10-18), as otherwise the leak checker at GitHub
Actions CI seems to fail with a false positive.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
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As the comment above the function indicates, we do not bother actually
storing commit messages in our anonymization map. But we still take the
message as a parameter, and just ignore it. Let's stop doing that, which
will make -Wunused-parameter happier.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The anonymization code has a specific generator callback for each type
of data (e.g., one for paths, one for oids, and so on). These all take a
"data" parameter, but none of them use it for anything. Which is not
surprising, as the point is to generate a new name independent of any
input, and each function keeps its own static counter.
We added the extra pointer in d5bf91fde44 (fast-export: add a "data"
callback parameter to anonymize_str(), 2020-06-23) to handle
--anonymize-map parsing, but that turned out to be awkward itself, and
was recently dropped.
So let's get rid of this "data" parameter that nobody is using, both
from the generators and from anonymize_str() which plumbed it through.
This simplifies the code, and makes -Wunused-parameter happier.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When we handle an --anonymize-map option, we parse the orig/anon pair,
and then feed the "orig" string to anonymize_str(), along with a
generator function that duplicates the "anon" string to be cached in the
map.
This works, because anonymize_str() says "ah, there is no mapping yet
for orig; I'll add one from the generator". But there are some
downsides:
1. It's a bit too clever, as it's not obvious what the code is trying
to do or why it works.
2. It requires allowing generator functions to take an extra void
pointer, which is not something any of the normal callers of
anonymize_str() want.
3. It does the wrong thing if the same token is provided twice.
When there are conflicting options, like:
git fast-export --anonymize \
--anonymize-map=foo:one \
--anonymize-map=foo:two
we usually let the second one override the first. But by using
anonymize_str(), which has first-one-wins logic, we do the
opposite.
So instead of relying on anonymize_str(), let's directly add the entry
ourselves. We can tweak the tests to show that we handle overridden
options correctly now.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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When anonymizing output, there's only one spot where we generate new
entries to add to our hashmap: when anonymize_str() doesn't find an
entry, we use the generate() callback to make one and add it. Let's pull
that into its own function in preparation for another caller.
Note that we'll add one extra feature. In anonymize_str(), we know that
we won't find an existing entry in the hashmap (since it will only try
to add after failing to find one). But other callers won't have the same
behavior, so we should catch this case and free the now-dangling entry.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We take pains to avoid doing a lookup on a hashmap which has not been
initialized with hashmap_init(). That was necessary back when this code
was written. But hashmap_get() became safer in b7879b0ba6e (hashmap:
allow re-use after hashmap_free(), 2020-11-02). Since then it's OK to
call functions on a zero-initialized table; it will just correctly
return NULL, since there is no match.
This simplifies the code a little, and also lets us keep the
initialization line closer to when we add an entry (which is when the
hashmap really does need to be totally initialized). That will help
later refactoring.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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We store anonymized values as pointers to "const char *", since they are
conceptually const to callers who use them. But they are actually
allocated strings whose memory is owned by the struct.
The ownership mismatch hasn't been a big deal since we never free() them
(they are held until the program ends), but let's switch them to "char *"
in preparation for changing that.
Since most code only accesses them via anonymize_str(), it can continue
to narrow them to "const char *" in its return value.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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"git range-diff" code clean-up. Needed to pacify modern GCC versions.
* jk/range-diff-fixes:
range-diff: use ssize_t for parsed "len" in read_patches()
range-diff: handle unterminated lines in read_patches()
range-diff: drop useless "offset" variable from read_patches()
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Deal with a few deprecation warning from cURL library.
* jk/curl-avoid-deprecated-api:
http: support CURLOPT_PROTOCOLS_STR
http: prefer CURLOPT_SEEKFUNCTION to CURLOPT_IOCTLFUNCTION
http-push: prefer CURLOPT_UPLOAD to CURLOPT_PUT
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Adjust the GitHub CI to newer ubuntu release.
* jx/ci-ubuntu-fix:
github-actions: run gcc-8 on ubuntu-20.04 image
ci: install python on ubuntu
ci: use the same version of p4 on both Linux and macOS
ci: remove the pipe after "p4 -V" to catch errors
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Meant to go with js/ci-gcc-12-fixes.
source: <xmqq7d68ytj8.fsf_-_@gitster.g>
* jc/http-clear-finished-pointer:
http.c: clear the 'finished' member once we are done with it
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Fixes real problems noticed by gcc 12 and works around false
positives.
* js/ci-gcc-12-fixes:
nedmalloc: avoid new compile error
compat/win32/syslog: fix use-after-realloc
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In http.c, the run_active_slot() function allows the given "slot" to
make progress by calling step_active_slots() in a loop repeatedly,
and the loop is not left until the request held in the slot
completes.
Ages ago, we used to use the slot->in_use member to get out of the
loop, which misbehaved when the request in "slot" completes (at
which time, the result of the request is copied away from the slot,
and the in_use member is cleared, making the slot ready to be
reused), and the "slot" gets reused to service a different request
(at which time, the "slot" becomes in_use again, even though it is
for a different request). The loop terminating condition mistakenly
thought that the original request has yet to be completed.
Today's code, after baa7b67d (HTTP slot reuse fixes, 2006-03-10)
fixed this issue, uses a separate "slot->finished" member that is
set in run_active_slot() to point to an on-stack variable, and the
code that completes the request in finish_active_slot() clears the
on-stack variable via the pointer to signal that the particular
request held by the slot has completed. It also clears the in_use
member (as before that fix), so that the slot itself can safely be
reused for an unrelated request.
One thing that is not quite clean in this arrangement is that,
unless the slot gets reused, at which point the finished member is
reset to NULL, the member keeps the value of &finished, which
becomes a dangling pointer into the stack when run_active_slot()
returns. Clear the finished member before the control leaves the
function, which has a side effect of unconfusing compilers like
recent GCC 12 that is over-eager to warn against such an assignment.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Technically, the pointer difference `end - start` _could_ be negative,
and when cast to an (unsigned) `size_t` that would cause problems. In
this instance, the symptom is:
dir.c: In function 'git_url_basename':
dir.c:3087:13: error: 'memchr' specified bound [9223372036854775808, 0]
exceeds maximum object size 9223372036854775807
[-Werror=stringop-overread]
CC ewah/bitmap.o
3087 | if (memchr(start, '/', end - start) == NULL
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
While it is a bit far-fetched to think that `end` (which is defined as
`repo + strlen(repo)`) and `start` (which starts at `repo` and never
steps beyond the NUL terminator) could result in such a negative
difference, GCC has no way of knowing that.
See also https://gcc.gnu.org/bugzilla//show_bug.cgi?id=85783.
Let's just add a safety check, primarily for GCC's benefit.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Code clean-up for test framework.
* fc/test-aggregation-clean-up:
test: don't print aggregate-results command
test: simplify counts aggregation
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"git receive-pack" that responds to "git push" requests failed to
clean a stale lockfile when killed in the middle, which has been
corrected.
* ps/receive-pack-unlock-before-die:
receive-pack: fix stale packfile locks when dying
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Fix for a "ls-files --format="%(path)" that produced nonsense
output, which was a bug in 2.38.
* aj/ls-files-format-fix:
ls-files: fix "--format" output of relative paths
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"git format-patch" honors the src/dst prefixes set to nonstandard
values with configuration variables like "diff.noprefix", causing
receiving end of the patch that expects the standard -p1 format to
break. Teach "format-patch" to ignore end-user configuration and
always use the standard prefixes.
This is a backward compatibility breaking change.
* jk/format-patch-ignore-noprefix:
rebase: prefer --default-prefix to --{src,dst}-prefix for format-patch
format-patch: add format.noprefix option
format-patch: do not respect diff.noprefix
diff: add --default-prefix option
t4013: add tests for diff prefix options
diff: factor out src/dst prefix setup
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There were two reasons we didn't do this. As "git am" is designed
to grok e-mailed patches, not necessarily taken out of a Git
repostiory or even if it came from a Git repository not necessarily
produced with format-patch, we didn't want to single it out as the
"blessed" input producer to the command. Also, in the original
workflow that "git am" was invented for, the user of "am" was
expected to be a different person than the users of "format-patch".
But this is a very safe change to make in 2023. Thanks to the
effort by many contributors, Git ended up becoming a bit more
popular than we initially thought it would be, and "format-patch",
which took me a few weeks to pursuade Linus to take in 2005, seems
to have become the de-facto standard tool to produce patch e-mails.
Interestingly, the documentation for "git apply", which is listed in
SEE ALSO section of "git am" documentation, does mention "am" and
"format-patch" as two things that are related but different from
"apply" in an early part.
Suggested-by: Kai Grossjohann <kai.grossjohann@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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In 2007 the docbook project made the mistake of converting ' to \' for
man pages [1]. It's a problem because groff interprets \' as acute
accent which is rendered as ' in ASCII, but as ยด in utf-8.
This started a cascade of bug reports in git [2], debian [3], Arch Linux
[4], docbook itself [5], and probably many others.
A solution was to use the correct groff character: \(aq, which is always
rendered as ', but the problem is that such character doesn't work in
other troff programs.
A portable solution required the use of a conditional character that is
\(aq in groff, but ' in all others:
.ie \n(.g .ds Aq \(aq
.el .ds Aq '
The proper solution took time to be implemented in docbook, but in 2010
they did it [6]. So the docbook man page stylesheets were broken from
1.73 to 1.76.
Unfortunately by that point many workarounds already existed. In the
case of git, GNU_ROFF was introduced, and in the case of Arch Linux
a mapping from \' to ' was added to groff's man.local. Other
distributions might have done the same, or similar workarounds.
Since 2010 there is no need for this workaround, which is fixed
elsewhere, not just in docbook, but other layers as well.
Let's remove it.
[1] https://github.com/docbook/xslt10-stylesheets/commit/ea2a0bac56c56eec1892ac3d9254dca89f7c5746
[2] https://lore.kernel.org/git/20091012102926.GA3937@debian.b2j/
[3] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=507673#65
[4] https://bugs.archlinux.org/task/9643
[5] https://sourceforge.net/p/docbook/bugs/1022/
[6] https://github.com/docbook/xslt10-stylesheets/commit/fb553434265906ed81edc6d5f533d0b08d200046
Inspired-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Use gettimeofday instead of time(NULL) to get current time.
This avoids clock skew on glibc 2.31+ on Linux, where in the
first 1 to 2.5 ms of every second, time(NULL) returns a
value that is one less than the tv_sec part of
higher-resolution timestamps such as those returned by
gettimeofday or timespec_get, or those in the file system.
There are similar clock skew problems on AIX and MS-Windows,
which have problems in the first 5 ms of every second.
Without this patch, users can observe Git issuing a
timestamp T+1 before it issues timestamp T, because Git
sometimes uses time(NULL) or time(&t) and sometimes uses
higher-res methods like gettimeofday. Although strictly
speaking users should tolerate this behavior because a
superuser can always change the clock back, this is a
quality of implementation issue and users naturally expect
Git to issue timestamps in increasing order unless the
superuser has fiddled with the system clock.
This patch always uses gettimeofday(...) instead of time(...),
and I have verified that the resulting .o files never refer
to the name 'time'. A trickier patch would change only
those calls for which timestamp monotonicity is user-visible.
Such a patch would require more expertise about Git internals,
though, and would be harder to maintain later.
Another possibility would be to change Git's documentation
to warn users that Git does not always issue timestamps in
increasing order. However, Git users would likely be either
dismayed by this possibility, or confused by the level of
detail that any such documentation would require.
Yet another possibility would be to fix the Linux kernel so
that the time syscall is consistent with the other timestamp
syscalls. I suppose this has not been done due to
performance implications. (Git's use of timestamps is rare
enough that performance is not a significant consideration
for git.) However, this wouldn't fix Git's problem on older
Linux kernels, or on AIX or MS-Windows.
Signed-off-by: Paul Eggert <eggert@cs.ucla.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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With the change in the last commit to move several functions to
write-or-die.h, csum-file.h no longer needs to include cache.h.
However, removing that include forces several other C files, which
directly or indirectly dependend upon csum-file.h's inclusion of
cache.h, to now be more explicit about their dependencies.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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By moving several declarations to setup.h, the previous patch made it
possible to remove the include of cache.h in several source files. Do
so.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The last several commits were geared at replacing the include of cache.h
in strbuf.c with an include of git-compat-util.h. Unfortunately, I had
to drop a patch moving some functions from cache.h to object-name.h, due
to excessive conflicts with other in-flight topics.
However, even without that patch, the series of patches so far allows us
to modify a number of C files to replace an include of cache.h with
git-compat-util.h. Do that to reduce our dependencies.
(If we could have kept our object-name.h patch in this series, it would
have also let us reduce the includes in checkout.c and fmt-merge-msg.c
in addition to strbuf.c).
Just to ensure that nothing else was bringing in cache.h, all of the
affected files have been checked to ensure that
gcc -E -I. $SOURCE_FILE | grep '"cache.h"'
found no hits and that
make DEVELOPER=1 ${OBJECT_FILE_FOR_SOURCE_FILE}
successfully compiles without warnings.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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expand_user_path() was renamed to interpolate_path() back in mid-2021,
but reinstated with a #define and a NEEDSWORK comment that we would
eventually want to get rid of it. Do so now.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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This is another step towards letting us remove the include of cache.h in
strbuf.c. It does mean that we also need to add includes of abspath.h
in a number of C files.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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This is one step towards making strbuf.c not depend upon cache.h.
Additional steps will follow in subsequent commits.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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A number of files were apparently including cache.h solely to get
gettext.h. By making those files explicitly include gettext.h, we can
already drop the include of cache.h in these files. On top of that,
there were some files using cache.h that didn't need to for any reason.
Remove these unnecessary includes.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Looking at things from the opposite angle of the last patch, we had a
few files that were including gettext.h and perhaps needed it at some
point in history, but no longer require it. Remove the include.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Dozens of files made use of gettext functions, without explicitly
including gettext.h. This made it more difficult to find which files
could remove a dependence on cache.h. Make C files explicitly include
gettext.h if they are using it.
However, while compat/fsmonitor/fsm-ipc-darwin.c should also gain an
include of gettext.h, it was left out to avoid conflicting with an
in-flight topic.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Ever since a64215b6cd ("object.h: stop depending on cache.h; make
cache.h depend on object.h", 2023-02-24), we have a few headers that
could have replaced their include of cache.h with an include of
object.h. Make that change now.
Some C files had to start including cache.h after this change (or some
smaller header it had brought in), because the C files were depending
on things from cache.h but were only formerly implicitly getting
cache.h through one of these headers being modified in this patch.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Both 'git for-each-ref --merged=<X>' and 'git branch --merged=<X>' use
the ref-filter machinery to select references or branches (respectively)
that are reachable from a set of commits presented by one or more
--merged arguments. This happens within reach_filter(), which uses the
revision-walk machinery to walk history in a standard way.
However, the commit-reach.c file is full of custom searches that are
more efficient, especially for reachability queries that can terminate
early when reachability is discovered. Add a new
tips_reachable_from_bases() method to commit-reach.c and call it from
within reach_filter() in ref-filter.c. This affects both 'git branch'
and 'git for-each-ref' as tested in p1500-graph-walks.sh.
For the Linux kernel repository, we take an already-fast algorithm and
make it even faster:
Test HEAD~1 HEAD
-------------------------------------------------------------------
1500.5: contains: git for-each-ref --merged 0.13 0.02 -84.6%
1500.6: contains: git branch --merged 0.14 0.02 -85.7%
1500.7: contains: git tag --merged 0.15 0.03 -80.0%
(Note that we remove the iterative 'git rev-list' test from p1500
because it no longer makes sense as a comparison to 'git for-each-ref'
and would just waste time running it for these comparisons.)
The algorithm is implemented in commit-reach.c in the method
tips_reachable_from_base(). This method takes a string_list of tips and
assigns the 'util' for each item with the value 1 if the base commit can
reach those tips.
Like other reachability queries in commit-reach.c, the fastest way to
search for "can A reach B?" is to do a depth-first search up to the
generation number of B, preferring to explore first parents before later
parents. While we must walk all reachable commits up to that generation
number when the answer is "no", the depth-first search can answer "yes"
much faster than other approaches in most cases.
This search becomes trickier when there are multiple targets for the
depth-first search. The commits with lower generation number are more
likely to be within the history of the start commit, but we don't want
to waste time searching commits of low generation number if the commit
target with lowest generation number has already been found.
The trick here is to take the input commits and sort them by generation
number in ascending order. Track the index within this order as
min_generation_index. When we find a commit, if its index in the list is
equal to min_generation_index, then we can increase the generation
number boundary of our search to the next-lowest value in the list.
With this mechanism, the number of commits to search is minimized with
respect to the depth-first search heuristic. We will walk all commits up
to the minimum generation number of a commit that is _not_ reachable
from the start, but we will walk only the necessary portion of the
depth-first search for the reachable commits of lower generation.
Add extra tests for this behavior in t6600-test-reach.sh as the
interesting data shape of that repository can sometimes demonstrate
corner case bugs.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The previous change implemented the ahead_behind() method, including an
algorithm to compute the ahead/behind values for a number of commit tips
relative to a number of commit bases. Now, integrate that algorithm as
part of 'git for-each-ref' hidden behind a new format atom,
ahead-behind. This naturally extends to 'git branch' and 'git tag'
builtins, as well.
This format allows specifying multiple bases, if so desired, and all
matching references are compared against all of those bases. For this
reason, failing to read a reference provided from these atoms results in
an error.
In order to translate the ahead_behind() method information to the
format output code in ref-filter.c, we must populate arrays of
ahead_behind_count structs. In struct ref_array, we store the full array
that will be passed to ahead_behind(). In struct ref_array_item, we
store an array of pointers that point to the relvant items within the
full array. In this way, we can pull all relevant ahead/behind values
directly when formatting output for a specific item. It also ensures the
lifetime of the ahead_behind_count structs matches the time that the
array is being used.
Add specific tests of the ahead/behind counts in t6600-test-reach.sh, as
it has an interesting repository shape. In particular, its merging
strategy and its use of different commit-graphs would demonstrate over-
counting if the ahead_behind() method did not already account for that
possibility.
Also add tests for the specific for-each-ref, branch, and tag builtins.
In the case of 'git tag', there are intersting cases that happen when
some of the selected tips are not commits. This requires careful logic
around commits_nr in the second loop of filter_ahead_behind(). Also, the
test in t7004 is carefully located to avoid being dependent on the GPG
prereq. It also avoids using the test_commit helper, as that will add
ticks to the time and disrupt the expected timestamps in later tag
tests.
Also add performance tests in a new p1300-graph-walks.sh script. This
will be useful for more uses in the future, but for now compare the
ahead-behind counting algorithm in 'git for-each-ref' to the naive
implementation by running 'git rev-list --count' processes for each
input.
For the Git source code repository, the improvement is already obvious:
Test this tree
---------------------------------------------------------------
1500.2: ahead-behind counts: git for-each-ref 0.07(0.07+0.00)
1500.3: ahead-behind counts: git branch 0.07(0.06+0.00)
1500.4: ahead-behind counts: git tag 0.07(0.06+0.00)
1500.5: ahead-behind counts: git rev-list 1.32(1.04+0.27)
But the standard performance benchmark is the Linux kernel repository,
which demosntrates a significant improvement:
Test this tree
---------------------------------------------------------------
1500.2: ahead-behind counts: git for-each-ref 0.27(0.24+0.02)
1500.3: ahead-behind counts: git branch 0.27(0.24+0.03)
1500.4: ahead-behind counts: git tag 0.28(0.27+0.01)
1500.5: ahead-behind counts: git rev-list 4.57(4.03+0.54)
The 'git rev-list' test exists in this change as a demonstration, but it
will be removed in the next change to avoid wasting time on this
comparison.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Fully implement the commit-counting logic required to determine
ahead/behind counts for a batch of commit pairs. This is a new library
method within commit-reach.h. This method will be linked to the
for-each-ref builtin in the next change.
The interface for ahead_behind() uses two arrays. The first array of
commits contains the list of all starting points for the walk. This
includes all tip commits _and_ base commits. The second array specifies
base/tip pairs by pointing to commits within the first array, by index.
The second array also stores the resulting ahead/behind counts for each
of these pairs.
This implementation of ahead_behind() allows multiple bases, if desired.
Even with multiple bases, there is only one commit walk used for
counting the ahead/behind values, saving time when the base/tip ranges
overlap significantly.
This interface for ahead_behind() also makes it very easy to call
ensure_generations_valid() on the entire array of bases and tips. This
call is necessary because it is critical that the walk that counts
ahead/behind values never walks a commit more than once. Without
generation numbers on every commit, there is a possibility that a
commit date skew could cause the walk to revisit a commit and then
double-count it. For this reason, it is strongly recommended that 'git
ahead-behind' is only run in a repository with a commit-graph file that
covers most of the reachable commits, storing precomputed generation
numbers. If no commit-graph exists, this walk will be much slower as it
must walk all reachable commits in ensure_generations_valid() before
performing the counting logic.
It is possible to detect if generation numbers are available at run time
and redirect the implementation to another algorithm that does not
require this property. However, that implementation requires a commit
walk per base/tip pair _and_ can be slower due to the commit date
heuristics required. Such an implementation could be considered in the
future if there is a reason to include it, but most Git hosts should
already be generating a commit-graph file as part of repository
maintenance. Most Git clients should also be generating commit-graph
files as part of background maintenance or automatic GCs.
Now, let's discuss the ahead/behind counting algorithm.
The first array of commits are considered the starting commits. The
index within that array will play a critical role.
We create a new commit slab that maps commits to a bitmap. For a given
commit (anywhere in the history), its bitmap stores information relative
to which of the input commits can reach that commit. The ith bit will be
on if the ith commit from the starting list can reach that commit. It is
important to notice that these bitmaps are not the typical "reachability
bitmaps" that are stored in .bitmap files. Instead of signalling which
objects are reachable from the current commit, they instead signal
"which starting commits can reach me?" It is also important to know that
the bitmap is not necessarily "complete" until we walk that commit. We
will perform a commit walk by generation number in such a way that we
can guarantee the bitmap is correct when we visit that commit.
At the beginning of the ahead_behind() method, we initialize the bitmaps
for each of the starting commits. By enabling the ith bit for the ith
starting commit, we signal "the ith commit can reach itself."
We walk commits by popping the commit with maximum generation number out
of the queue, guaranteeing that we will never walk a child of that
commit in any future steps.
As we walk, we load the bitmap for the current commit and perform two
main steps. The _second_ step examines each parent of the current commit
and adds the current commit's bitmap bits to each parent's bitmap. (We
create a new bitmap for the parent if this is our first time seeing that
parent.) After adding the bits to the parent's bitmap, the parent is
added to the walk queue. Due to this passing of bits to parents, the
current commit has a guarantee that the ith bit is enabled on its bitmap
if and only if the ith commit can reach the current commit.
The first step of the walk is to examine the bitmask on the current
commit and decide which ranges the commit is in or not. Due to the "bit
pushing" in the second step, we have a guarantee that the ith bit of the
current commit's bitmap is on if and only if the ith starting commit can
reach it. For each ahead_behind_count struct, check the base_index and
tip_index to see if those bits are enabled on the current bitmap. If
exactly one bit is enabled, then increment the corresponding 'ahead' or
'behind' count. This increment is the reason we _absolutely need_ to
walk commits at most once.
The only subtle thing to do with this walk is to check to see if a
parent has all bits on in its bitmap, in which case it becomes "stale"
and is marked with the STALE bit. This allows queue_has_nonstale() to be
the terminating condition of the walk, which greatly reduces the number
of commits walked if all of the commits are nearby in history. It avoids
walking a large number of common commits when there is a deep history.
We also use the helper method insert_no_dup() to add commits to the
priority queue without adding them multiple times. This uses the PARENT2
flag. Thus, we must clear both the STALE and PARENT2 bits of all
commits, in case ahead_behind() is called multiple times in the same
process.
Co-authored-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Use the just-introduced compute_reachable_generation_numbers_1() to
implement a function which dynamically computes topological levels (or
corrected commit dates) for out-of-graph commits.
This will be useful for the ahead-behind algorithm we are about to
introduce, which needs accurate topological levels on _all_ commits
reachable from the tips in order to avoid over-counting.
Co-authored-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The commit_graph_generation() method used to report a value of
GENERATION_NUMBER_INFINITY if the commit_graph_data_slab had an instance
for the given commit but the graph_pos indicated the commit was not in
the commit-graph file.
However, an upcoming change will introduce the ability to set generation
values in-memory without writing the commit-graph file. Thus, we can no
longer trust 'graph_pos' to indicate whether or not the generation
member can be trusted.
Instead, trust the 'generation' member if the commit has a value in the
slab _and_ the 'generation' member is non-zero. Otherwise, treat it as
GENERATION_NUMBER_INFINITY.
This only makes a difference for a very old case for the commit-graph:
the very first Git release to write commit-graph files wrote zeroes in
the topological level positions. If we are parsing a commit-graph with
all zeroes, those commits will now appear to have
GENERATION_NUMBER_INFINITY (as if they were not parsed from the
commit-graph).
I attempted several variations to work around the need for providing an
uninitialized 'generation' member, but this was the best one I found. It
does require a change to a verification test in t5318 because it reports
a different error than the one about non-zero generation numbers.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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The previous change introduced the generic algorithm
compute_reachable_generation_numbers() and used it as the core
functionality of compute_topological_levels(). Now, use it as the core
functionality of compute_generation_numbers().
The main difference here is that we use generation version 2, which is
used in to toggle the logic in compute_generation_from_max() for
computing the corrected commit date based on the corrected commit dates
of the parent commits (and the commit date of the current commit). It
also uses different methods for (get|set)_generation in the vtable in
order to store and access the value in the correct places.
Co-authored-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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