The recent addition of the index.skipHash config option allows index
writes to speed up by skipping the hash computation for the trailing
checksum. This is particularly critical for repositories with many files
at HEAD, so add this config option to two cases where users in that
scenario may opt-in to such behavior:
1. The feature.manyFiles config option enables some options that are
helpful for repositories with many files at HEAD.
2. 'scalar register' and 'scalar reconfigure' set config options that
optimize for large repositories.
In both of these cases, set index.skipHash=true to gain this
speedup. Add tests that demonstrate the proper way that
index.skipHash=true can override feature.manyFiles=true.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The previous change allowed skipping the hashing portion of the
hashwrite API, using it instead as a buffered write API. Disabling the
hashwrite can be particularly helpful when the write operation is in a
critical path.
One such critical path is the writing of the index. This operation is so
critical that the sparse index was created specifically to reduce the
size of the index to make these writes (and reads) faster.
This trade-off between file stability at rest and write-time performance
is not easy to balance. The index is an interesting case for a couple
reasons:
1. Writes block users. Writing the index takes place in many user-
blocking foreground operations. The speed improvement directly
impacts their use. Other file formats are typically written in the
background (commit-graph, multi-pack-index) or are super-critical to
correctness (pack-files).
2. Index files are short lived. It is rare that a user leaves an index
for a long time with many staged changes. Outside of staged changes,
the index can be completely destroyed and rewritten with minimal
impact to the user.
Following a similar approach to one used in the microsoft/git fork [1],
add a new config option (index.skipHash) that allows disabling this
hashing during the index write. The cost is that we can no longer
validate the contents for corruption-at-rest using the trailing hash.
[1] 21fed2d914
We load this config from the repository config given by istate->repo,
with a fallback to the_repository if it is not set.
While older Git versions will not recognize the null hash as a special
case, the file format itself is still being met in terms of its
structure. Using this null hash will still allow Git operations to
function across older versions.
The one exception is 'git fsck' which checks the hash of the index file.
This used to be a check on every index read, but was split out to just
the index in a33fc72fe9 (read-cache: force_verify_index_checksum,
2017-04-14) and released first in Git 2.13.0. Document the versions that
relaxed these restrictions, with the optimistic expectation that this
change will be included in Git 2.40.0.
Here, we disable this check if the trailing hash is all zeroes. We add a
warning to the config option that this may cause undesirable behavior
with older Git versions.
As a quick comparison, I tested 'git update-index --force-write' with
and without index.skipHash=true on a copy of the Linux kernel
repository.
Benchmark 1: with hash
Time (mean ± σ): 46.3 ms ± 13.8 ms [User: 34.3 ms, System: 11.9 ms]
Range (min … max): 34.3 ms … 79.1 ms 82 runs
Benchmark 2: without hash
Time (mean ± σ): 26.0 ms ± 7.9 ms [User: 11.8 ms, System: 14.2 ms]
Range (min … max): 16.3 ms … 42.0 ms 69 runs
Summary
'without hash' ran
1.78 ± 0.76 times faster than 'with hash'
These performance benefits are substantial enough to allow users the
ability to opt-in to this feature, even with the potential confusion
with older 'git fsck' versions.
Test this new config option, both at a command-line level and within a
submodule. The confirmation is currently limited to confirm that 'git
fsck' does not complain about the index. Future updates will make this
test more robust.
It is critical that this test is placed before the test_index_version
tests, since those tests obliterate the .git/config file and hence lose
the setting from GIT_TEST_DEFAULT_HASH, if set.
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A GNU make pattern rule with multiple targets has always meant that
a single invocation of the recipe will build all the targets.
However in older versions of GNU make a recipe that did not really
build all the targets would be tolerated.
Starting with GNU make 4.4 this behavior is deprecated and pattern
rules are expected to generate files to match all the patterns.
If not all targets are created then GNU make will not consider any
target up to date and will re-run the recipe when it is run again.
Modify Documentation/Makefile to split the man page-creating pattern
rule into a separate pattern rule for each pattern.
Reported-by: Alexander Kanavin <alex.kanavin@gmail.com>
Signed-off-by: Paul Smith <psmith@gnu.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git receive-pack" used to use all the local refs as the boundary for
checking connectivity of the data "git push" sent, but now it uses
only the refs that it advertised to the pusher. In a repository with
the .hideRefs configuration, this reduces the resources needed to
perform the check.
cf. <221028.86bkpw805n.gmgdl@evledraar.gmail.com>
cf. <xmqqr0yrizqm.fsf@gitster.g>
* ps/receive-use-only-advertised:
receive-pack: only use visible refs for connectivity check
rev-parse: add `--exclude-hidden=` option
revision: add new parameter to exclude hidden refs
revision: introduce struct to handle exclusions
revision: move together exclusion-related functions
refs: get rid of global list of hidden refs
refs: fix memory leak when parsing hideRefs config
A pair of bugfixes to the Documentation/howto/maintain-git.txt guide.
* tb/howto-maintain-git-fixes:
Documentation: build redo-seen.sh from jch..seen
Documentation: build redo-jch.sh from master..jch
'git maintenance register' is taught to write configuration to an
arbitrary path, and 'git for-each-repo' is taught to expand tilde
characters in paths.
* rp/maintenance-qol:
builtin/gc.c: fix use-after-free in maintenance_unregister()
maintenance --unregister: fix uninit'd data use & -Wdeclaration-after-statement
maintenance: add option to register in a specific config
for-each-repo: interpolate repo path arguments
Update the credential-cache documentation to provide a more realistic
example.
* mh/increase-credential-cache-timeout:
Documentation: increase example cache timeout to 1 hour
"git repack" learns to send cruft objects out of the way into
packfiles outside the repository.
* tb/repack-expire-to:
builtin/repack.c: implement `--expire-to` for storing pruned objects
builtin/repack.c: write cruft packs to arbitrary locations
builtin/repack.c: pass "cruft_expiration" to `write_cruft_pack`
builtin/repack.c: pass "out" to `prepare_pack_objects`
Add a new `--exclude-hidden=` option that is similar to the one we just
added to git-rev-list(1). Given a section name `uploadpack` or `receive`
as argument, it causes us to exclude all references that would be hidden
by the respective `$section.hideRefs` configuration.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Users can optionally hide refs from remote users in git-upload-pack(1),
git-receive-pack(1) and others via the `transfer.hideRefs`, but there is
not an easy way to obtain the list of all visible or hidden refs right
now. We'll require just that though for a performance improvement in our
connectivity check.
Add a new option `--exclude-hidden=` that excludes any hidden refs from
the next pseudo-ref like `--all` or `--branches`.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
maintenance register currently records the maintenance repo exclusively
within the user's global configuration, but other configuration files
may be relevant when running maintenance if they are included from the
global config. This option allows the user to choose where maintenance
repos are recorded.
Signed-off-by: Ronan Pigott <ronan@rjp.ie>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Previously the docs only described storage helpers.
A concrete example: Git Credential Manager can generate credentials
for GitHub and GitLab via OAuth.
https://github.com/GitCredentialManager/git-credential-manager
Signed-off-by: M Hickford <mirth.hickford@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Git learned pushing submodules without pushing the superproject by
the user specifying --recurse-submodules=only through 6c656c3fe4
("submodules: add RECURSE_SUBMODULES_ONLY value", 2016-12-20) and
225e8bf778 ("push: add option to push only submodules", 2016-12-20).
For users who use this feature regularly, it is desirable to have an
equivalent configuration.
It turns out that such a configuration (push.recurseSubmodules=only) is
already supported, even though it is neither documented nor mentioned
in the commit messages, due to the way the --recurse-submodules=only
feature was implemented (a function used to parse --recurse-submodules
was updated to support "only", but that same function is used to parse
push.recurseSubmodules too). What is left is to document it and test it,
which is what this commit does.
There is a possible point of confusion when recursing into a submodule
that itself has the push.recurseSubmodules=only configuration, because
if a repository has only its submodules pushed and not itself, its
superproject can never be pushed. Therefore, treat such configurations
as being "on-demand", and print a warning message.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
It was previously unclear how unrecognised attributes are handled.
Signed-off-by: M Hickford <mirth.hickford@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Remotes are considered "promisor" if extensions.partialClone and some
other configuration variables are set. The casing for this in
Documentation/technical/repository-version.txt is not proper and may
cause confusion. This change corrects this casing.
Signed-off-by: Kousik Sanagavarapu <five231003@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Previously, the example *decreased* the cache timeout compared to the
default, making it less user friendly.
Instead, nudge users to make cache more usable. Many users choose
store over cache.
https://lore.kernel.org/git/CAGJzqskRYN49SeS8kSEN5-vbB_Jt1QvAV9QhS6zNuKh0u8wxPQ@mail.gmail.com/
The default timeout remains 15 minutes. A stronger nudge would
be to increase that.
Signed-off-by: M Hickford <mirth.hickford@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
The glossary entries for "commit-graph file" and "reachability
bitmap" have been added.
* po/glossary-around-traversal:
glossary: add reachability bitmap description
glossary: add "commit graph" description
doc: use 'object database' not ODB or abbreviation
doc: use "commit-graph" hyphenation consistently
Enable gc.cruftpacks by default for those who opt into
feature.experimental setting.
* es/mark-gc-cruft-as-experimental:
config: let feature.experimental imply gc.cruftPacks=true
gc: add tests for --cruft and friends
Git asks for a "password", but the user might use a
personal access token or OAuth access token instead.
Example:
Password for 'https://AzureDiamond@github.com':
Signed-off-by: M Hickford <mirth.hickford@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Once upon a time, Matheus wrote some patches to make
git grep [--cached | <REVISION>] ...
restrict its output to the sparsity specification when working in a
sparse checkout[1]. That effort got derailed by two things:
(1) The --sparse-index work just beginning which we wanted to avoid
creating conflicts for
(2) Never deciding on flag and config names and planned high level
behavior for all commands.
More recently, Shaoxuan implemented a more limited form of Matheus'
patches that only affected --cached, using a different flag name,
but also changing the default behavior in line with what Matheus did.
This again highlighted the fact that we never decided on command line
flag names, config option names, and the big picture path forward.
The --sparse-index work has been mostly complete (or at least released
into production even if some small edges remain) for quite some time
now. We have also had several discussions on flag and config names,
though we never came to solid conclusions. Stolee once upon a time
suggested putting all these into some document in
Documentation/technical[3], which Victoria recently also requested[4].
I'm behind the times, but here's a patch attempting to finally do that.
[1] https://lore.kernel.org/git/5f3f7ac77039d41d1692ceae4b0c5df3bb45b74a.1612901326.git.matheus.bernardino@usp.br/
(See his second link in that email in particular)
[2] https://lore.kernel.org/git/20220908001854.206789-2-shaoxuan.yuan02@gmail.com/
[3] https://lore.kernel.org/git/CABPp-BHwNoVnooqDFPAsZxBT9aR5Dwk5D9sDRCvYSb8akxAJgA@mail.gmail.com/
(Scroll to the very end for the final few paragraphs)
[4] https://lore.kernel.org/git/cafcedba-96a2-cb85-d593-ef47c8c8397c@github.com/
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
In a similar spirit as the previous commit, the 'seen' branch gets
rebuilt by reintegrating topics between 'jch' and the (old) tip of
'seen'.
Update the instructions on how to generate Meta/redo-seen.sh for the
first time to reflect this.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Rebuilding the 'jch' branch begins by reintegrating any topics between
'master' and 'jch', not 'master' and 'seen'.
In the maintainer guide, the documentation isn't quite right, since the
initial input to Meta/Reintegrate is "master..seen", not "master..jch".
This can lead to confusing results when generating the Meta/redo-jch.sh
script for the first time.
Additionally, rebuilding 'jch' takes place in two steps. First, running
the script up to the first "### match next" cut-line, and then comparing
the result with what's on 'next' (i.e. with "git diff jch next"). Then,
the remaining set of topics get merged down to 'jch' (which aren't on
'next') by running the entire "redo-jch.sh" script.
Clarify the documentation to reflect this.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Derrick Stolee