Build procedure update plus introduction of Meson based builds.
* ps/build: (24 commits)
Introduce support for the Meson build system
Documentation: add comparison of build systems
t: allow overriding build dir
t: better support for out-of-tree builds
Documentation: extract script to generate a list of mergetools
Documentation: teach "cmd-list.perl" about out-of-tree builds
Documentation: allow sourcing generated includes from separate dir
Makefile: simplify building of templates
Makefile: write absolute program path into bin-wrappers
Makefile: allow "bin-wrappers/" directory to exist
Makefile: refactor generators to be PWD-independent
Makefile: extract script to generate gitweb.js
Makefile: extract script to generate gitweb.cgi
Makefile: extract script to massage Python scripts
Makefile: extract script to massage Shell scripts
Makefile: use "generate-perl.sh" to massage Perl library
Makefile: extract script to massage Perl scripts
Makefile: consistently use PERL_PATH
Makefile: generate doc versions via GIT-VERSION-GEN
Makefile: generate "git.rc" via GIT-VERSION-GEN
...
Fix performance regression of a recent "fatten promisor pack with
local objects" protection against an unwanted gc.
* jt/fix-fattening-promisor-fetch:
index-pack --promisor: also check commits' trees
index-pack --promisor: don't check blobs
index-pack --promisor: dedup before checking links
The syntax ":/<text>" to name the latest commit with the matching
text was broken with a recent change, which has been corrected.
* ps/commit-with-message-syntax-fix:
object-name: fix reversed ordering with ":/<text>" revisions
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"
"git tag" has been taught to refuse to create refs/tags/HEAD
as such a tag will be confusing in the context of UI provided by
the Git Porcelain commands.
* jc/forbid-head-as-tagname:
tag: "git tag" refuses to use HEAD as a tagname
t5604: do not expect that HEAD can be a valid tagname
refs: drop strbuf_ prefix from helpers
refs: move ref name helpers around
"git describe" optimization.
* jk/describe-perf:
describe: split "found all tags" and max_candidates logic
describe: stop traversing when we run out of names
describe: stop digging for max_candidates+1
t/perf: add tests for git-describe
t6120: demonstrate weakness in disjoint-root handling
The --ancestry-path option is designed to be given a commit that is
on the path, which was not documented, which has been corrected.
* kk/doc-ancestry-path:
doc: mention rev-list --ancestry-path restrictions
Yet another "pass the repository through the callchain" topic.
* kn/midx-wo-the-repository:
midx: inline the `MIDX_MIN_SIZE` definition
midx: pass down `hash_algo` to functions using global variables
midx: pass `repository` to `load_multi_pack_index`
midx: cleanup internal usage of `the_repository` and `the_hash_algo`
midx-write: pass down repository to `write_midx_file[_only]`
write-midx: add repository field to `write_midx_context`
midx-write: use `revs->repo` inside `read_refs_snapshot`
midx-write: pass down repository to static functions
packfile.c: remove unnecessary prepare_packed_git() call
midx: add repository to `multi_pack_index` struct
config: make `packed_git_(limit|window_size)` non-global variables
config: make `delta_base_cache_limit` a non-global variable
packfile: pass down repository to `for_each_packed_object`
packfile: pass down repository to `has_object[_kept]_pack`
packfile: pass down repository to `odb_pack_name`
packfile: pass `repository` to static function in the file
packfile: use `repository` from `packed_git` directly
packfile: add repository to struct `packed_git`
Backport oss-fuzz tests for us to our codebase.
* es/oss-fuzz:
fuzz: port fuzz-url-decode-mem from OSS-Fuzz
fuzz: port fuzz-parse-attr-line from OSS-Fuzz
fuzz: port fuzz-credential-from-url-gently from OSS-Fuzz
"git fast-import" learned to reject paths with ".." and "." as
their components to avoid creating invalid tree objects.
* en/fast-import-verify-path:
t9300: test verification of renamed paths
fast-import: disallow more path components
fast-import: disallow "." and ".." path components
"git bundle --unbundle" and "git clone" running on a bundle file
both learned to trigger fsck over the new objects with configurable
fck check levels.
* jt/bundle-fsck:
transport: propagate fsck configuration during bundle fetch
fetch-pack: split out fsck config parsing
bundle: support fsck message configuration
bundle: add bundle verification options type
Optimize reading random references out of the reftable backend by
allowing reuse of iterator objects.
* ps/reftable-iterator-reuse:
refs/reftable: reuse iterators when reading refs
reftable/merged: drain priority queue on reseek
reftable/stack: add mechanism to notify callers on reload
refs/reftable: refactor reflog expiry to use reftable backend
refs/reftable: refactor reading symbolic refs to use reftable backend
refs/reftable: read references via `struct reftable_backend`
refs/reftable: figure out hash via `reftable_stack`
reftable/stack: add accessor for the hash ID
refs/reftable: handle reloading stacks in the reftable backend
refs/reftable: encapsulate reftable stack
Isolates the reftable subsystem from the rest of Git's codebase by
using fewer pieces of Git's infrastructure.
* ps/reftable-detach:
reftable/system: provide thin wrapper for lockfile subsystem
reftable/stack: drop only use of `get_locked_file_path()`
reftable/system: provide thin wrapper for tempfile subsystem
reftable/stack: stop using `fsync_component()` directly
reftable/system: stop depending on "hash.h"
reftable: explicitly handle hash format IDs
reftable/system: move "dir.h" to its only user
Loosen overly strict ownership check introduced in the recent past,
to keep the promise "cloning a suspicious repository is a safe
first step to inspect it".
* bc/allow-upload-pack-from-other-people:
Allow cloning from repositories owned by another user
End-user experience of "git mergetool" when the command errors out
has been improved.
* pb/mergetool-errors:
git-difftool--helper.sh: exit upon initialize_merge_tool errors
git-mergetool--lib.sh: add error message for unknown tool variant
git-mergetool--lib.sh: add error message if 'setup_user_tool' fails
git-mergetool--lib.sh: use TOOL_MODE when erroring about unknown tool
completion: complete '--tool-help' in 'git mergetool'
Describe a case where an option value needs to be spelled as a
separate argument, i.e. "--opt val", not "--opt=val".
* jc/doc-opt-tilde-expand:
doc: option value may be separate for valid reasons
Drop support for ancient environments in various CI jobs.
* bc/ancient-ci:
Add additional CI jobs to avoid accidental breakage
ci: remove clause for Ubuntu 16.04
gitlab-ci: switch from Ubuntu 16.04 to 20.04
Commit c08589efdc (index-pack: repack local links into promisor packs,
2024-11-01) seems to contain an oversight in that the tree of a commit
is not checked. Teach git to check these trees.
The fix slows down a fetch from a certain repo at $DAYJOB from 2m2.127s
to 2m45.052s, but in order to make the fetch correct, it seems worth it.
In order to test this, we could create server and client repos as
follows...
C S
\ /
O
(O and C are commits both on the client and server. S is a commit
only on the server. C and S have the same tree but different commit
messages. The diff between O and C is non-zero.)
...and then, from the client, fetch S from the server.
In theory, the client declares "have C" and the server can use this
information to exclude S's tree (since it knows that the client has C's
tree, which is the same as S's tree). However, it is also possible for
the server to compute that it needs to send S and not O, and proceed
from there; therefore the objects of C are not considered at all when
determining what to send in the packfile. In order to prevent a test of
client functionality from having such a dependence on server behavior, I
have not included such a test.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As a follow-up to the parent of this commit, it was found that not
checking for the existence of blobs linked from trees sped up the fetch
from 24m47.815s to 2m2.127s. Teach Git to do that.
The tradeoff of not checking blobs is documented in a code comment.
(Blobs may also be linked from tag objects, but it is impossible to know
the type of an object linked from a tag object without looking it up in
the object database, so the code for that is untouched.)
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Commit c08589efdc (index-pack: repack local links into promisor packs,
2024-11-01) fixed a bug with what was believed to be a negligible
decrease in performance [1] [2]. But at $DAYJOB, with at least one repo,
it was found that the decrease in performance was very significant.
Looking at the patch, whenever we parse an object in the packfile to
be indexed, we check the targets of all its outgoing links for its
existence. However, this could be optimized by first collecting all such
targets into an oidset (thus deduplicating them) before checking. Teach
Git to do that.
On a certain fetch from the aforementioned repo, this improved
performance from approximately 7 hours to 24m47.815s. This number will
be further reduced in a subsequent patch.
[1] https://lore.kernel.org/git/CAG1j3zGiNMbri8rZNaF0w+yP+6OdMz0T8+8_Wgd1R_p1HzVasg@mail.gmail.com/
[2] https://lore.kernel.org/git/20241105212849.3759572-1-jonathantanmy@google.com/
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Recently it was reported [1] that "look for the youngest commit
reachable from any ref with log message that match the given
pattern" syntax (i.e. ':/<text>') started to return results in
reverse recency order. This regression was introduced in Git v2.47.0
and is caused by a memory leak fix done in 57fb139b5e (object-name:
fix leaking commit list items, 2024-08-01).
The intent of the identified commit is to stop modifying the commit list
provided by the caller such that the caller can properly free all commit
list items, including those that the called function might potentially
remove from the list. This was done by creating a copy of the passed-in
commit list and modifying this copy instead of the caller-provided list.
We already knew to create such a copy beforehand with the `backup` list,
which was used to clear the `ONELINE_SEEN` commit mark after we were
done. So the refactoring simply renamed that list to `copy` and started
to operate on that list instead. There is a gotcha though: the backup
list, and thus now also the copied list, is always being prepended to,
so the resulting list is in reverse order! The end result is that we
pop commits from the wrong end of the commit list, returning commits in
reverse recency order.
Fix the bug by appending to the list instead.
[1]: <CAKOEJdcPYn3O01p29rVa+xv=Qr504FQyKJeSB-Moze04ViCGGg@mail.gmail.com>
Reported-by: Aarni Koskela <aarni@valohai.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Introduce support for the Meson build system, a "modern" meta build
system that supports many different platforms, including Linux, macOS,
Windows and BSDs. Meson supports different backends, including Ninja,
Xcode and Microsoft Visual Studio. Several common IDEs provide an
integration with it.
The biggest contender compared to Meson is probably CMake as outlined in
our "Documentation/technical/build-systems.txt" file. Based on my own
personal experience from working with both build systems extensively I
strongly favor Meson over CMake. In my opinion, it feels significantly
easier to use with a syntax that feels more like a "real" programming
language. The second big reason is that Meson supports Rust natively,
which may prove to be important given that the project may pick up Rust
as another language eventually.
Using Meson is rather straight-forward. An example:
```
# Meson uses out-of-tree builds. You can set up multiple build
# directories, how you name them is completely up to you.
$ mkdir build
$ cd build
$ meson setup .. -Dprefix=/tmp/git-installation
# Build the project. This also provides several other targets like
e.g. `install` or `test`.
$ ninja
# Meson has been wired up to support execution of our test suites.
# Both our unit tests and our integration tests are supported.
# Running `meson test` without any arguments will execute all tests,
# but the syntax supports globbing to select only some tests.
$ meson test 't-*'
# Execute single test interactively to allow for debugging.
$ meson test 't0000-*' --interactive --test-args=-ix
```
The build instructions have been successfully tested on the following
systems, tests are passing:
- Apple macOS 10.15.
- FreeBSD 14.1.
- NixOS 24.11.
- OpenBSD 7.6.
- Ubuntu 24.04.
- Windows 10 with Cygwin.
- Windows 10 with MinGW64, except for t9700, which is also broken with
our Makefile.
- Windows 10 with Visual Studio 2022 toolchain, using the Native Tools
Command Prompt with `meson setup --vsenv`. Tests pass, except for
t9700.
- Windows 10 with Visual Studio 2022 solution, using the Native Tools
Command Prompt with `meson setup --backend vs2022`. Tests pass,
except for t9700.
- Windows 10 with VS Code, using the Meson plug-in.
It is expected that there will still be rough edges in the current
version. If this patch lands the expectation is that it will coexist
with our other build systems for a while. Like this, distributions can
slowly migrate over to Meson and report any findings they have to us
such that we can continue to iterate. A potential cutoff date for other
build systems may be Git 3.0.
Some notes:
- The installed distribution is structured somewhat differently than
how it used to be the case. All of our binaries are installed into
`$libexec/git-core`, while all binaries part of `$bindir` are now
symbolic links pointing to the former. This rule is consistent in
itself and thus easier to reason about.
- We do not install dashed binaries into `$libexec/git-core` anymore,
so there won't e.g. be a symlink for git-add(1). These are not
required by modern Git and there isn't really much of a use case for
those anymore. By not installing those symlinks we thus start the
deprecation of this layout.
- We're targeting Meson 1.3.0, which has been released relatively
recently November 2023. The only feature we use from that version is
`fs.relative_to()`, which we could replace if necessary. If so, we
could start to target Meson 1.0.0 and newer, released in December
2022.
- The whole build instructions count around 3300 lines, half of which
is listing all of our code and test files. Our Makefiles are around
5000 lines, autoconf adds another 1300 lines. CMake in comparison
has only 1200 linescode, but it avoids listing individual files and
does not wire up auto-configuration as extensively as the Meson
instructions do.
- We bundle a set of subproject wrappers for curl, expat, openssl,
pcre2 and zlib. This allows developers to build Git without these
dependencies preinstalled, and Meson will fetch and build them
automatically. This is especially helpful on Windows.
Helped-by: Eli Schwartz <eschwartz@gentoo.org>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We're contemplating whether to eventually replace our build systems with
a build system that is easier to use. Add a comparison of build systems
to our technical documentation as a baseline for discussion.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our "test-lib.sh" assumes that our build directory is the parent
directory of "t/". While true when using our Makefile, it's not when
using build systems that support out-of-tree builds.
In commit ee9e66e4e7 (cmake: avoid editing t/test-lib.sh, 2022-10-18),
we have introduce support for overriding the GIT_BUILD_DIR by creating
the file "$GIT_BUILD_DIR/GIT-BUILD-DIR" with its contents pointing to
the location of the build directory. The intent was to stop modifying
"t/test-lib.sh" with the CMake build systems while allowing out-of-tree
builds. But "$GIT_BUILD_DIR" is somewhat misleadingly named, as it in
fact points to the _source_ directory. So while that commit solved part
of the problem for out-of-tree builds, CMake still has to write files
into the source tree.
Solve the second part of the problem, namely not having to write any
data into the source directory at all, by also supporting an environment
variable that allows us to point to a different build directory. This
allows us to perform properly self-contained out-of-tree builds.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our in-tree builds used by the Makefile use various different build
directories scattered around different locations. The paths to those
build directories have to be propagated to our tests such that they can
find the contained files. This is done via a mixture of hardcoded paths
in our test library and injected variables in our bin-wrappers or
"GIT-BUILD-OPTIONS".
The latter two mechanisms are preferable over using hardcoded paths. For
one, we have all paths which are subject to change stored in a small set
of central files instead of having the knowledge of build paths in many
files. And second, it allows build systems which build files elsewhere
to adapt those paths based on their own needs. This is especially nice
in the context of build systems that use out-of-tree builds like CMake
or Meson.
Remove hardcoded knowledge of build paths from our test library and move
it into our bin-wrappers and "GIT-BUILD-OPTIONS".
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We include the list of available mergetools into our manpages. Extract
the script that performs this logic such that we can reuse it in other
build systems.
While at it, refactor the Makefile targets such that we don't create
"mergetools-list.made" anymore. It shouldn't be necessary, as we can
instead have other targets depend on "mergetools-{diff,merge}.txt"
directly.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The "cmd-list.perl" script generates a list of commands that can be
included into our manpages. The script doesn't know about out-of-tree
builds and instead writes resulting files into the source directory.
Adapt it such that we can read data from the source directory and write
data into the build directory.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Our documentation uses "include::" directives to include parts that are
either reused across multiple documents or parts that we generate at
build time. Unfortunately, top-level includes are only ever resolved
relative to the base directory, which is typically the directory of the
including document. Most importantly, it is not possible to have either
asciidoc or asciidoctor search multiple directories.
It follows that both kinds of includes must live in the same directory.
This is of course a bummer for out-of-tree builds, because here the
dynamically-built includes live in the build directory whereas the
static includes live in the source directory.
Introduce a `build_dir` attribute and prepend it to all of our includes
for dynamically-built files. This attribute gets set to the build
directory and thus converts the include path to an absolute path, which
asciidoc and asciidoctor know how to resolve.
Note that this change also requires us to update "build-docdep.perl",
which tries to figure out included files such our Makefile can set up
proper build-time dependencies. This script simply scans through the
source files for any lines that match "^include::" and treats the
remainder of the line as included file path. But given that those may
now contain the "{build_dir}" variable we have to teach the script to
replace that attribute with the actual build directory.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we install Git we also install a set of default templates that both
git-init(1) and git-clone(1) populate into our build directories. The
way the pristine templates are laid out in our source directory is
somewhat weird though: instead of reconstructing the actual directory
hierarchy in "templates/", we represent directory separators with "--".
The only reason I could come up with for why we have this is the
"branches/" directory, which is supposed to be empty when installing it.
And as Git famously doesn't store empty directories at all we have to
work around this limitation.
Now the thing is that the "branches/" directory is a leftover to how
branches used to be stored in the dark ages. gitrepository-layout(5)
lists this directory as "slightly deprecated", which I would claim is a
strong understatement. I have never encountered anybody using it today
and would be surprised if it even works as expected. So having the "--"
hack in place for an item that is basically unused, unmaintained and
deprecated doesn't only feel unreasonable, but installing that entry by
default may also cause confusion for users that do not know what this is
supposed to be in the first place.
Remove this directory from our templates and, now that we do not require
the workaround anymore, restructure the templates to form a proper
hierarchy. This makes it way easier for build systems to install these
templates into place.
We should likely think about removing support for "branch/" altogether,
but that is outside of the scope of this patch series.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Write the absolute program path into our bin-wrappers. This allows us to
simplify the Meson build instructions we are about to introduce a bit.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The "bin-wrappers/" directory gets created by our build system and is
populated with one script for each of our binaries. There isn't anything
inherently wrong with the current layout, but it is somewhat hard to
adapt for out-of-tree build systems.
Adapt the layout such that our "bin-wrappers/" directory always exists
and contains our "wrap-for-bin.sh" script to make things a little bit
easier for subsequent steps.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We have multiple scripts that generate headers from other data. All of
these scripts have the assumption built-in that they are executed in the
current source directory, which makes them a bit unwieldy to use during
out-of-tree builds.
Refactor them to instead take the source directory as well as the output
file as arguments.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Similar to the preceding commit, also extract the script to generate the
"gitweb.js" file. While the logic itself is trivial, it helps us avoid
duplication of logic across build systems and ensures that the build
systems will remain in sync with each other in case the logic ever needs
to change.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In order to generate "gitweb.cgi" we have to replace various different
placeholders. This is done ad-hoc and is thus not easily reusable across
different build systems.
Introduce a new GITWEB-BUILD-OPTIONS.in template that we populate at
configuration time with the expected options. This script is then used
as input for a new "generate-gitweb.sh" script that generates the final
"gitweb.cgi" file. While this requires us to repeat the options multiple
times, it is in line to how we generate other build options like our
GIT-BUILD-OPTIONS file.
While at it, refactor how we replace the GITWEB_PROJECT_MAXDEPTH. Even
though this variable is supposed to be an integer, the source file has
the value quoted. The quotes are eventually stripped via sed(1), which
replaces `"@GITWEB_PROJECT_MAXDEPTH@"` with the actual value, which is
rather nonsensical. This is made clearer by just dropping the quotes in
the source file.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Extract a script that massages Python scripts. This provides a couple of
benefits:
- The build logic is deduplicated across Make, CMake and Meson.
- CMake learns to rewrite scripts as-needed at build time instead of
only writing them at configure time.
Furthermore, we will use this script when introducing Meson to
deduplicate the logic across build systems.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Same as in the preceding commits, extract a script that allows us to
unify how we massage shell scripts.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Extend "generate-perl.sh" such that it knows to also massage the Perl
library files. There are two major differences:
- We do not read in the Perl header. This is handled by matching on
whether or not we have a Perl shebang.
- We substitute some more variables, which we read in via our
GIT-BUILD-OPTIONS.
Adapt both our Makefile and the CMake build instructions to use this.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Extract the script to inject various build-time parameters into our Perl
scripts into a standalone script. This is done such that we can reuse it
in other build systems.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When injecting the Perl path into our scripts we sometimes use '@PERL@'
while we othertimes use '@PERL_PATH@'. Refactor the code use the latter
consistently, which makes it easier to reuse the same logic for multiple
scripts.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The documentation we generate embeds information for the exact Git
version used as well as the date of the commit. This information is
injected by injecting attributes into the build process via command line
argument.
Refactor the logic so that we write the information into "asciidoc.conf"
and "asciidoctor-extensions.rb" via `GIT-VERSION-GEN` for AsciiDoc and
AsciiDoctor, respectively.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The "git.rc" is used on Windows to embed information like the project
name and version into the resulting executables. As such we need to
inject the version information, which we do by using preprocessor
defines. The logic to do so is non-trivial and needs to be kept in sync
with the different build systems.
Refactor the logic so that we generate "git.rc" via `GIT-VERSION-GEN`.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Junio C Hamano