Opening multiple instance of the same MIDX can lead to problems like two
separate packed_git structures which represent the same pack being added
to the repository's object store.
The above scenario can happen because prepare_midx_pack() checks if
`m->packs[pack_int_id]` is NULL in order to determine if a pack has been
opened and installed in the repository before. But a caller can
construct two copies of the same MIDX by calling get_multi_pack_index()
and load_multi_pack_index() since the former manipulates the
object store directly but the latter is a lower-level routine which
allocates a new MIDX for each call.
So if prepare_midx_pack() is called on multiple MIDXs with the same
pack_int_id, then that pack will be installed twice in the object
store's packed_git pointer.
This can lead to problems in, for e.g., the pack-bitmap code, which does
something like the following (in pack-bitmap.c:open_pack_bitmap()):
struct bitmap_index *bitmap_git = ...;
for (p = get_all_packs(r); p; p = p->next) {
if (open_pack_bitmap_1(bitmap_git, p) == 0)
ret = 0;
}
which is a problem if two copies of the same pack exist in the
packed_git list because pack-bitmap.c:open_pack_bitmap_1() contains a
conditional like the following:
if (bitmap_git->pack || bitmap_git->midx) {
/* ignore extra bitmap file; we can only handle one */
warning("ignoring extra bitmap file: %s", packfile->pack_name);
close(fd);
return -1;
}
Avoid this scenario by not letting write_midx_internal() open a MIDX
that isn't also pointed at by the object store. So long as this is the
case, other routines should prefer to open MIDXs with
get_multi_pack_index() or reprepare_packed_git() instead of creating
instances on their own. Because get_multi_pack_index() returns
`r->object_store->multi_pack_index` if it is non-NULL, we'll only have
one instance of a MIDX open at one time, avoiding these problems.
To encourage this, drop the `struct multi_pack_index *` parameter from
`write_midx_internal()`, and rely instead on the `object_dir` to find
(or initialize) the correct MIDX instance.
Likewise, replace the call to `close_midx()` with
`close_object_store()`, since we're about to replace the MIDX with a new
one and should invalidate the object store's memory of any MIDX that
might have existed beforehand.
Note that this now forbids passing object directories that don't belong
to alternate repositories over `--object-dir`, since before we would
have happily opened a MIDX in any directory, but now restrict ourselves
to only those reachable by `r->objects->multi_pack_index` (and alternate
MIDXs that we can see by walking the `next` pointer).
As far as I can tell, supporting arbitrary directories with
`--object-dir` was a historical accident, since even the documentation
says `<alt>` when referring to the value passed to this option.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The soon-to-be-implemented multi-pack bitmap treats object in the first
bit position specially by assuming that all objects in the pack it was
selected from are also represented from that pack in the MIDX. In other
words, the pack from which the first object was selected must also have
all of its other objects selected from that same pack in the MIDX in
case of any duplicates.
But this assumption relies on the fact that there is at least one object
in that pack to begin with; otherwise the object in the first bit
position isn't from a preferred pack, in which case we can no longer
assume that all objects in that pack were also selected from the same
pack.
Guard this assumption by checking the number of objects in the given
preferred pack, and failing if the given pack is empty.
To make sure we can safely perform this check, open any packs which are
contained in an existing MIDX via prepare_midx_pack(). The same is done
for new packs via the add_pack_to_midx() callback, but packs picked up
from a previous MIDX will not yet have these opened.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Update the technical documentation to describe the multi-pack bitmap
format. This patch merely introduces the new format, and describes its
high-level ideas. Git does not yet know how to read nor write these
multi-pack variants, and so the subsequent patches will:
- Introduce code to interpret multi-pack bitmaps, according to this
document.
- Then, introduce code to write multi-pack bitmaps from the 'git
multi-pack-index write' sub-command.
Finally, the implementation will gain tests in subsequent patches (as
opposed to inline with the patch teaching Git how to write multi-pack
bitmaps) to avoid a cyclic dependency.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Earlier "git log -m" was changed to always produce patch output,
which would break existing scripts, which has been reverted.
* jn/log-m-does-not-imply-p:
Revert 'diff-merges: let "-m" imply "-p"'
This reverts commit f5bfcc823b, which
made "git log -m" imply "--patch" by default. The logic was that
"-m", which makes diff generation for merges perform a diff against
each parent, has no use unless I am viewing the diff, so we could save
the user some typing by turning on display of the resulting diff
automatically. That wasn't expected to adversely affect scripts
because scripts would either be using a command like "git diff-tree"
that already emits diffs by default or would be combining -m with a
diff generation option such as --name-status. By saving typing for
interactive use without adversely affecting scripts in the wild, it
would be a pure improvement.
The problem is that although diff generation options are only relevant
for the displayed diff, a script author can imagine them affecting
path limiting. For example, I might run
git log -w --format=%H -- README
hoping to list commits that edited README, excluding whitespace-only
changes. In fact, a whitespace-only change is not TREESAME so the use
of -w here has no effect (since we don't apply these diff generation
flags to the diff_options struct rev_info::pruning used for this
purpose), but the documentation suggests that it should work
Suppose you specified foo as the <paths>. We shall call
commits that modify foo !TREESAME, and the rest TREESAME. (In
a diff filtered for foo, they look different and equal,
respectively.)
and a script author who has not tested whitespace-only changes
wouldn't notice.
Similarly, a script author could include
git log -m --first-parent --format=%H -- README
to filter the first-parent history for commits that modified README.
The -m is a no-op but it reflects the script author's intent. For
example, until 1e20a407fe (stash list: stop passing "-m" to "git
log", 2021-05-21), "git stash list" did this.
As a result, we can't safely change "-m" to imply "-p" without fear of
breaking such scripts. Restore the previous behavior.
Noticed because Rust's src/bootstrap/bootstrap.py made use of this
same construct: https://github.com/rust-lang/rust/pull/87513. That
script has been updated to omit the unnecessary "-m" option, but we
can expect other scripts in the wild to have similar expectations.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The local changes stashed by "git merge --autostash" were lost when
the merge failed in certain ways, which has been corrected.
* pb/merge-autostash-more:
merge: apply autostash if merge strategy fails
merge: apply autostash if fast-forward fails
Documentation: define 'MERGE_AUTOSTASH'
merge: add missing word "strategy" to a message
Reorganize and update the SubmitingPatches document.
* ab/update-submitting-patches:
SubmittingPatches: replace discussion of Travis with GitHub Actions
SubmittingPatches: move discussion of Signed-off-by above "send"
Documentation around GIT_CONFIG has been updated.
* jk/config-env-doc:
doc/git-config: simplify "override" advice for FILES section
doc/git-config: clarify GIT_CONFIG environment variable
doc/git-config: explain --file instead of referring to GIT_CONFIG
Three hyphens are rendered verbatim, so "--" has to be used to produce a
dash. There is no double arrow ("<->" is rendered as "<→"), so a left
and right arrow "<-->" have to be combined for that.
So fix asciidoc output for special characters. This is similar to fixes
in commit de82095a95 (doc hash-function-transition: fix asciidoc output,
2021-02-05).
Signed-off-by: Andrei Rybak <rybak.a.v@gmail.com>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Documentation on "git diff -l<n>" and diff.renameLimit have been
updated, and the defaults for these limits have been raised.
* en/rename-limits-doc:
rename: bump limit defaults yet again
diffcore-rename: treat a rename_limit of 0 as unlimited
doc: clarify documentation for rename/copy limits
diff: correct warning message when renameLimit exceeded
A guideline for gender neutral documentation has been added.
* ds/gender-neutral-doc-guidelines:
CodingGuidelines: recommend gender-neutral description
"git worktree add --lock" learned to record why the worktree is
locked with a custom message.
* sm/worktree-add-lock:
worktree: teach `add` to accept --reason <string> with --lock
worktree: mark lock strings with `_()` for translation
t2400: clean up '"add" worktree with lock' test
The documentation for 'git merge --abort' and 'git merge --quit' both
mention the special ref 'MERGE_AUTOSTASH', but this ref is not formally
defined anywhere. Mention it in the description of the '--autostash'
option for 'git merge'.
Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git rev-list" learns to omit the "commit <object-name>" header
lines from the output with the `--no-commit-header` option.
* bc/rev-list-without-commit-line:
rev-list: add option for --pretty=format without header
"git send-email" optimization.
* ab/send-email-optim:
perl: nano-optimize by replacing Cwd::cwd() with Cwd::getcwd()
send-email: move trivial config handling to Perl
perl: lazily load some common Git.pm setup code
send-email: lazily load modules for a big speedup
send-email: get rid of indirect object syntax
send-email: use function syntax instead of barewords
send-email: lazily shell out to "git var"
send-email: lazily load config for a big speedup
send-email: copy "config_regxp" into git-send-email.perl
send-email: refactor sendemail.smtpencryption config parsing
send-email: remove non-working support for "sendemail.smtpssl"
send-email tests: test for boolean variables without a value
send-email tests: support GIT_TEST_PERL_FATAL_WARNINGS=true
Replace the discussion of Travis CI added in
0e5d028a7a (Documentation: add setup instructions for Travis CI,
2016-05-02) with something that covers the GitHub Actions added in
889cacb689 (ci: configure GitHub Actions for CI/PR, 2020-04-11).
The setup is trivial compared to using Travis, and it even works on
Windows (that "hopefully soon" comment was probably out-of-date on
Travis as well).
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Move the section discussing the addition of a SOB trailer above the
section that discusses generating the patch itself. This makes sense
as we don't want someone to go through the process of "git
format-patch", only to realize late that they should have used "git
commit -s" or equivalent.
This is a move-only change, no lines here are being altered, only
moved around.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git pull --rebase=false" means we merge their history into ours, but
it has been described the other way around.
Cc: Stephen Haberman <stephen@exigencecorp.com>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
[jc: updated the log message]
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The doc for 'submodule.recurse' starts with "Specifies if commands
recurse into submodles by default". This is not exactly true of all
commands that have a '--recurse-submodules' option. For example, 'git
pull --recurse-submodules' does not run 'git pull' in each submodule,
but rather runs 'git submodule update --recursive' so that the submodule
working trees after the pull matches the commits recorded in the
superproject.
Clarify that by just saying that it enables '--recurse-submodules'.
Note that the way this setting interacts with 'fetch.recurseSubmodules'
and 'push.recurseSubmodules', which can have other values than true or
false, is already documented since 4da9e99e6e (doc: be more precise on
(fetch|push).recurseSubmodules, 2020-04-06).
Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
At the end of the FILES section, we indicate that you can override the
regular lookup rules with --global, etc. But:
- we're missing the --local option
- we point to GIT_CONFIG instead of --file, but the latter has much
better documentation
- we're vague about how the overrides work; the actual option
descriptions are much better here
So let's just mention the names and point people back to the OPTIONS
section. We could perhaps even delete this paragraph entirely, but the
presence of the names may give people reading FILES a clue about where
to look for more information.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The scope and utility of the GIT_CONFIG variable was drastically reduced
by dc87183189 (Only use GIT_CONFIG in "git config", not other programs,
2008-06-30). But the documentation in git-config(1) predates that, which
makes it rather misleading.
These days it is really just another way to say "--file". So let's say
that, and explicitly make it clear that it does not impact other Git
commands (like GIT_CONFIG_SYSTEM, etc, would).
I also bumped it to the bottom of the list of variables, and warned
people off of using it. We don't have any plans for deprecation at this
point, but there's little point in encouraging people to use it by
putting it at the top of the list.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The explanation for the --file option only refers to GIT_CONFIG. This
redirection to an environment variable is confusing, but doubly so
because the description of GIT_CONFIG is out of date.
Let's describe --file from scratch, detailing both the reading and
writing behavior as we do for other similar options like --system, etc.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Update the documentation not to assume users are of certain gender
and adds to guidelines to do so.
* ds/gender-neutral-doc:
*: fix typos
comments: avoid using the gender of our users
doc: avoid using the gender of other people
Code recently added to support common ancestry negotiation during
"git push" did not sanity check its arguments carefully enough.
* ab/fetch-negotiate-segv-fix:
fetch: fix segfault in --negotiate-only without --negotiation-tip=*
fetch: document the --negotiate-only option
send-pack.c: move "no refs in common" abort earlier
Technical writing seeks to convey information with minimal
friction. One way that a reader can experience friction is if they
encounter a description of "a user" that is later simplified using a
gendered pronoun. If the reader does not consider that pronoun to
apply to them, then they can experience cognitive dissonance that
removes focus from the information.
Give some basic tips to guide us avoid unnecessary uses of gendered
description.
Using a gendered pronoun is appropriate when referring to a specific
person.
There are acceptable existing uses of gendered pronouns within the
Git codebase, such as:
* References to real people (e.g. Linus Torvalds, "the Git maintainer").
Do not misgender real people. If there is any doubt to the gender of a
person, then avoid using pronouns.
* References to fictional people with clear genders (e.g. Alice and
Bob).
* Sample text used in test cases (e.g t3702, t6432).
* The official text of the GPL license contains uses of "he or she",
but using singular "they" (or modifying the text in some other
way) is not within the scope of the Git project.
* Literal email messages in Documentation/howto/ should not be edited
for grammatical concerns such as this, unless we update the entire
document to fit the standard documentation format. If such an effort is
taken on, then the authorship would change and no longer refer to the
exact mail message.
* External projects consumed in contrib/ should not deviate solely for
style reasons. Recommended edits should be contributed to those
projects directly.
Other cases within the Git project were cleaned up by the previous
changes.
Co-authored-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
These were last bumped in commit 92c57e5c1d (bump rename limit
defaults (again), 2011-02-19), and were bumped both because processors
had gotten faster, and because people were getting ugly merges that
caused problems and reporting it to the mailing list (suggesting that
folks were willing to spend more time waiting).
Since that time:
* Linus has continued recommending kernel folks to set
diff.renameLimit=0 (maps to 32767, currently)
* Folks with repositories with lots of renames were happy to set
merge.renameLimit above 32767, once the code supported that, to
get correct cherry-picks
* Processors have gotten faster
* It has been discovered that the timing methodology used last time
probably used too large example files.
The last point is probably worth explaining a bit more:
* The "average" file size used appears to have been average blob size
in the linux kernel history at the time (probably v2.6.25 or
something close to it).
* Since bigger files are modified more frequently, such a computation
weights towards larger files.
* Larger files may be more likely to be modified over time, but are
not more likely to be renamed -- the mean and median blob size
within a tree are a bit higher than the mean and median of blob
sizes in the history leading up to that version for the linux
kernel.
* The mean blob size in v2.6.25 was half the average blob size in
history leading to that point
* The median blob size in v2.6.25 was about 40% of the mean blob size
in v2.6.25.
* Since the mean blob size is more than double the median blob size,
any file as big as the mean will not be compared to any files of
median size or less (because they'd be more than 50% dissimilar).
* Since it is the number of files compared that provides the O(n^2)
behavior, median-sized files should matter more than mean-sized
ones.
The combined effect of the above is that the file size used in past
calculations was likely about 5x too large. Combine that with a CPU
performance improvement of ~30%, and we can increase the limits by
a factor of sqrt(5/(1-.3)) = 2.67, while keeping the original stated
time limits.
Keeping the same approximate time limit probably makes sense for
diff.renameLimit (there is no progress feedback in e.g. git log -p),
but the experience above suggests merge.renameLimit could be extended
significantly. In fact, it probably would make sense to have an
unlimited default setting for merge.renameLimit, but that would
likely need to be coupled with changes to how progress is displayed.
(See https://lore.kernel.org/git/YOx+Ok%2FEYvLqRMzJ@coredump.intra.peff.net/
for details in that area.) For now, let's just bump the approximate
time limit from 10s to 1m.
(Note: We do not want to use actual time limits, because getting results
that depend on how loaded your system is that day feels bad, and because
we don't discover that we won't get all the renames until after we've
put in a lot of work rather than just upfront telling the user there are
too many files involved.)
Using the original time limit of 2s for diff.renameLimit, and bumping
merge.renameLimit from 10s to 60s, I found the following timings using
the simple script at the end of this commit message (on an AWS c5.xlarge
which reports as "Intel(R) Xeon(R) Platinum 8124M CPU @ 3.00GHz"):
N Timing
1300 1.995s
7100 59.973s
So let's round down to nice even numbers and bump the limits from
400->1000, and from 1000->7000.
Here is the measure_rename_perf script (adapted from
https://lore.kernel.org/git/20080211113516.GB6344@coredump.intra.peff.net/
in particular to avoid triggering the linear handling from
basename-guided rename detection):
#!/bin/bash
n=$1; shift
rm -rf repo
mkdir repo && cd repo
git init -q -b main
mkdata() {
mkdir $1
for i in `seq 1 $2`; do
(sed "s/^/$i /" <../sample
echo tag: $1
) >$1/$i
done
}
mkdata initial $n
git add .
git commit -q -m initial
mkdata new $n
git add .
cd new
for i in *; do git mv $i $i.renamed; done
cd ..
git rm -q -rf initial
git commit -q -m new
time git diff-tree -M -l0 --summary HEAD^ HEAD
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In commit 89973554b5 (diffcore-rename: make diff-tree -l0 mean
-l<large>, 2017-11-29), -l0 was given a special magical "large" value,
but one which was not large enough for some uses (as can be seen from
commit 9f7e4bfa3b (diff: remove silent clamp of renameLimit,
2017-11-13). Make 0 (or a negative value) be treated as unlimited
instead and update the documentation to mention this.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A few places in the docs implied that rename/copy detection is always
quadratic or that all (unpaired) files were involved in the quadratic
portion of rename/copy detection. The following two commits each
introduced an exception to this:
9027f53cb5 (Do linear-time/space rename logic for exact renames,
2007-10-25)
bd24aa2f97 (diffcore-rename: guide inexact rename detection based
on basenames, 2021-02-14)
(As a side note, for copy detection, the basename guided inexact rename
detection is turned off and the exact renames will only result in
sources (without the dests) being removed from the set of files used in
quadratic detection. So, for copy detection, the documentation was
closer to correct.)
Avoid implying that all files involved in rename/copy detection are
subject to the full quadratic algorithm. While at it, also note the
default values for all these settings.
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The default reason stored in the lock file, "added with --lock",
is unlikely to be what the user would have given in a separate
`git worktree lock` command. Allowing `--reason` to be specified
along with `--lock` when adding a working tree gives the user control
over the reason for locking without needing a second command.
Signed-off-by: Stephen Manz <smanz@alum.mit.edu>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When `git diff --merge-base` was introduced at around Git 2.30, the
documentation included a few errors.
In the example given for `git diff --cached --merge-base`, the
`--cached` flag was omitted for the `--merge-base` example. Add the
missing flag.
In the `git diff <commit>` case, we failed to mention that
`--merge-base` is an available option. Give the usage of `--merge-base`
as an option there.
Finally, there are two errors in the usage of `git diff`. Firstly, we do
not mention `--merge-base` in the `git diff --cached` case. Mention it
so that it's consistent with the documentation. Secondly, we put the
`[--merge-base]` in between `<commit>` and `[<commit>...]`. Move the
`[--merge-base]` so that it's beside `[<options>]` which is a more
logical grouping.
Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In general, we encourage users to use plumbing commands, like git
rev-list, over porcelain commands, like git log, when scripting.
However, git rev-list has one glaring problem that prevents it from
being used in certain cases: when --pretty is used with a custom format,
it always prints out a line containing "commit" and the object ID. This
makes it unsuitable for many scripting needs, and forces users to use
git log instead.
While we can't change this behavior for backwards compatibility, we can
add an option to suppress this behavior, so let's do so, and call it
"--no-commit-header". Additionally, add the corresponding positive
option to switch it back on.
Note that this option doesn't affect the built-in formats, only custom
formats. This is exactly the same behavior as users already have from
git log and is what most users will be used to.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
