Commit Graph

11143 Commits

Author SHA1 Message Date
Junio C Hamano
d699e27bd4 Merge branch 'tb/ban-strtok'
Mark strtok() and strtok_r() to be banned.

* tb/ban-strtok:
  banned.h: mark `strtok()` and `strtok_r()` as banned
  t/helper/test-json-writer.c: avoid using `strtok()`
  t/helper/test-oidmap.c: avoid using `strtok()`
  t/helper/test-hashmap.c: avoid using `strtok()`
  string-list: introduce `string_list_setlen()`
  string-list: multi-delimiter `string_list_split_in_place()`
2023-05-02 10:13:35 -07:00
Junio C Hamano
fc23c397c7 Merge branch 'tb/enable-cruft-packs-by-default'
When "gc" needs to retain unreachable objects, packing them into
cruft packs (instead of exploding them into loose object files) has
been offered as a more efficient option for some time.  Now the use
of cruft packs has been made the default and no longer considered
an experimental feature.

* tb/enable-cruft-packs-by-default:
  repository.h: drop unused `gc_cruft_packs`
  builtin/gc.c: make `gc.cruftPacks` enabled by default
  t/t9300-fast-import.sh: prepare for `gc --cruft` by default
  t/t6500-gc.sh: add additional test cases
  t/t6500-gc.sh: refactor cruft pack tests
  t/t6501-freshen-objects.sh: prepare for `gc --cruft` by default
  t/t5304-prune.sh: prepare for `gc --cruft` by default
  builtin/gc.c: ignore cruft packs with `--keep-largest-pack`
  builtin/repack.c: fix incorrect reference to '-C'
  pack-write.c: plug a leak in stage_tmp_packfiles()
2023-04-28 16:03:03 -07:00
Junio C Hamano
a02675ad90 Merge branch 'ds/fsck-pack-revindex'
"git fsck" learned to validate the on-disk pack reverse index files.

* ds/fsck-pack-revindex:
  fsck: validate .rev file header
  fsck: check rev-index position values
  fsck: check rev-index checksums
  fsck: create scaffolding for rev-index checks
2023-04-27 16:00:59 -07:00
Junio C Hamano
849c8b3dbf Merge branch 'tb/pack-revindex-on-disk'
The on-disk reverse index that allows mapping from the pack offset
to the object name for the object stored at the offset has been
enabled by default.

* tb/pack-revindex-on-disk:
  t: invert `GIT_TEST_WRITE_REV_INDEX`
  config: enable `pack.writeReverseIndex` by default
  pack-revindex: introduce `pack.readReverseIndex`
  pack-revindex: introduce GIT_TEST_REV_INDEX_DIE_ON_DISK
  pack-revindex: make `load_pack_revindex` take a repository
  t5325: mark as leak-free
  pack-write.c: plug a leak in stage_tmp_packfiles()
2023-04-27 16:00:59 -07:00
Junio C Hamano
36628c56ed Merge branch 'ps/fix-geom-repack-with-alternates'
Geometric repacking ("git repack --geometric=<n>") in a repository
that borrows from an alternate object database had various corner
case bugs, which have been corrected.

* ps/fix-geom-repack-with-alternates:
  repack: disable writing bitmaps when doing a local repack
  repack: honor `-l` when calculating pack geometry
  t/helper: allow chmtime to print verbosely without modifying mtime
  pack-objects: extend test coverage of `--stdin-packs` with alternates
  pack-objects: fix error when same packfile is included and excluded
  pack-objects: fix error when packing same pack twice
  pack-objects: split out `--stdin-packs` tests into separate file
  repack: fix generating multi-pack-index with only non-local packs
  repack: fix trying to use preferred pack in alternates
  midx: fix segfault with no packs and invalid preferred pack
2023-04-25 13:56:20 -07:00
Junio C Hamano
80d268f309 Merge branch 'jk/protocol-cap-parse-fix'
The code to parse capability list for v0 on-wire protocol fell into
an infinite loop when a capability appears multiple times, which
has been corrected.

* jk/protocol-cap-parse-fix:
  v0 protocol: use size_t for capability length/offset
  t5512: test "ls-remote --heads --symref" filtering with v0 and v2
  t5512: allow any protocol version for filtered symref test
  t5512: add v2 support for "ls-remote --symref" test
  v0 protocol: fix sha1/sha256 confusion for capabilities^{}
  t5512: stop referring to "v1" protocol
  v0 protocol: fix infinite loop when parsing multi-valued capabilities
2023-04-25 13:56:20 -07:00
Junio C Hamano
0807e57807 Merge branch 'en/header-split-cache-h'
Header clean-up.

* en/header-split-cache-h: (24 commits)
  protocol.h: move definition of DEFAULT_GIT_PORT from cache.h
  mailmap, quote: move declarations of global vars to correct unit
  treewide: reduce includes of cache.h in other headers
  treewide: remove double forward declaration of read_in_full
  cache.h: remove unnecessary includes
  treewide: remove cache.h inclusion due to pager.h changes
  pager.h: move declarations for pager.c functions from cache.h
  treewide: remove cache.h inclusion due to editor.h changes
  editor: move editor-related functions and declarations into common file
  treewide: remove cache.h inclusion due to object.h changes
  object.h: move some inline functions and defines from cache.h
  treewide: remove cache.h inclusion due to object-file.h changes
  object-file.h: move declarations for object-file.c functions from cache.h
  treewide: remove cache.h inclusion due to git-zlib changes
  git-zlib: move declarations for git-zlib functions from cache.h
  treewide: remove cache.h inclusion due to object-name.h changes
  object-name.h: move declarations for object-name.c functions from cache.h
  treewide: remove unnecessary cache.h inclusion
  treewide: be explicit about dependence on mem-pool.h
  treewide: be explicit about dependence on oid-array.h
  ...
2023-04-25 13:56:20 -07:00
Taylor Blau
52acddf36c string-list: multi-delimiter string_list_split_in_place()
Enhance `string_list_split_in_place()` to accept multiple characters as
delimiters instead of a single character.

Instead of using `strchr(2)` to locate the first occurrence of the given
delimiter character, `string_list_split_in_place_multi()` uses
`strcspn(2)` to move past the initial segment of characters comprised of
any characters in the delimiting set.

When only a single delimiting character is provided, `strpbrk(2)` (which
is implemented with `strcspn(2)`) has equivalent performance to
`strchr(2)`. Modern `strcspn(2)` implementations treat an empty
delimiter or the singleton delimiter as a special case and fall back to
calling strchrnul(). Both glibc[1] and musl[2] implement `strcspn(2)`
this way.

This change is one step to removing `strtok(2)` from the tree. Note that
`string_list_split_in_place()` is not a strict replacement for
`strtok()`, since it will happily turn sequential delimiter characters
into empty entries in the resulting string_list. For example:

    string_list_split_in_place(&xs, "foo:;:bar:;:baz", ":;", -1)

would yield a string list of:

    ["foo", "", "", "bar", "", "", "baz"]

Callers that wish to emulate the behavior of strtok(2) more directly
should call `string_list_remove_empty_items()` after splitting.

To avoid regressions for the new multi-character delimter cases, update
t0063 in this patch as well.

[1]: https://sourceware.org/git/?p=glibc.git;a=blob;f=string/strcspn.c;hb=glibc-2.37#l35
[2]: https://git.musl-libc.org/cgit/musl/tree/src/string/strcspn.c?h=v1.2.3#n11

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-24 16:01:28 -07:00
Junio C Hamano
b64894c206 Merge branch 'ow/ref-filter-omit-empty'
"git branch --format=..." and "git format-patch --format=..."
learns "--omit-empty" to hide refs that whose formatting result
becomes an empty string from the output.

* ow/ref-filter-omit-empty:
  branch, for-each-ref, tag: add option to omit empty lines
2023-04-21 15:35:05 -07:00
Junio C Hamano
7ac228c994 Merge branch 'rn/sparse-describe'
"git describe --dirty" learns to work better with sparse-index.

* rn/sparse-describe:
  describe: enable sparse index for describe
2023-04-21 15:35:04 -07:00
Junio C Hamano
a4a4db8cf7 Merge branch 'gc/better-error-when-local-clone-fails-with-symlink'
"git clone --local" stops copying from an original repository that
has symbolic links inside its $GIT_DIR; an error message when that
happens has been updated.

* gc/better-error-when-local-clone-fails-with-symlink:
  clone: error specifically with --local and symlinked objects
2023-04-20 14:33:36 -07:00
Junio C Hamano
08bd076ce4 Merge branch 'rs/get-tar-commit-id-use-defined-const'
Code clean-up to replace a hardcoded constant with a CPP macro.

* rs/get-tar-commit-id-use-defined-const:
  get-tar-commit-id: use TYPEFLAG_GLOBAL_HEADER instead of magic value
2023-04-20 14:33:36 -07:00
Taylor Blau
e3e24de1bf builtin/gc.c: make gc.cruftPacks enabled by default
Back in 5b92477f89 (builtin/gc.c: conditionally avoid pruning objects
via loose, 2022-05-20), `git gc` learned the `--cruft` option and
`gc.cruftPacks` configuration to opt-in to writing cruft packs when
collecting or pruning unreachable objects.

Cruft packs were introduced with the merge in a50036da1a (Merge branch
'tb/cruft-packs', 2022-06-03). They address the problem of "loose object
explosions", where Git will write out many individual loose objects when
there is a large number of unreachable objects that have not yet aged
past `--prune=<date>`.

Instead of keeping track of those unreachable yet recent objects via
their loose object file's mtime, cruft packs collect all unreachable
objects into a single pack with a corresponding `*.mtimes` file that
acts as a table to store the mtimes of all unreachable objects. This
prevents the need to store unreachable objects as loose as they age out
of the repository, and avoids the problem of loose object explosions.

Beyond avoiding loose object explosions, cruft packs also act as a more
efficient mechanism to store unreachable objects as they age out of a
repository. This is because pairs of similar unreachable objects serve
as delta bases for one another.

In 5b92477f89, the feature was introduced as experimental. Since then,
GitHub has been running these patches in every repository generating
hundreds of millions of cruft packs along the way. The feature is
battle-tested, and avoids many pathological cases such as above. Users
who either run `git gc` manually, or via `git maintenance` can benefit
from having cruft packs.

As such, enable cruft pack generation to take place by default (by
making `gc.cruftPacks` have the default of "true" rather than "false).

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-18 14:56:48 -07:00
Taylor Blau
05b9013b71 builtin/gc.c: ignore cruft packs with --keep-largest-pack
When cruft packs were implemented, we never adjusted the code for `git
gc`'s `--keep-largest-pack` and `gc.bigPackThreshold` to ignore cruft
packs. This option and configuration option share a common
implementation, but including cruft packs is wrong in both cases:

  - Running `git gc --keep-largest-pack` in a repository where the
    largest pack is the cruft pack itself will make it impossible for
    `git gc` to prune objects, since the cruft pack itself is kept.

  - The same is true for `gc.bigPackThreshold`, if the size of the cruft
    pack exceeds the limit set by the caller.

In the future, it is possible that `gc.bigPackThreshold` could be used
to write a separate cruft pack containing any new unreachable objects
that entered the repository since the last time a cruft pack was
written.

There are some complexities to doing so, mainly around handling
pruning objects that are in an existing cruft pack that is above the
threshold (which would either need to be rewritten, or else delay
pruning). Rewriting a substantially similar cruft pack isn't ideal, but
it is significantly better than the status-quo.

If users have large cruft packs that they don't want to rewrite, they
can mark them as `*.keep` packs. But in general, if a repository has a
cruft pack that is so large it is slowing down GC's, it should probably
be pruned anyway.

In the meantime, ignore cruft packs in the common implementation for
both of these options, and add a pair of tests to prevent any future
regressions here.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-18 14:56:47 -07:00
Taylor Blau
c512f31109 builtin/repack.c: fix incorrect reference to '-C'
When cruft packs were originally being developed, `-C` was designated as
the short-form for `--cruft` (as in `git repack -C`).

This was dropped due to confusion with Git's top-level `-C` option
before submitting to the list. But the reference to it in
`--cruft-expiration`'s help text was never updated. Fix that dangling
reference in this patch.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-18 14:56:47 -07:00
Junio C Hamano
3c957e6d39 Merge branch 'pw/rebase-cleanup-merge-strategy-option-handling'
Clean-up of the code path that deals with merge strategy option
handling in "git rebase".

* pw/rebase-cleanup-merge-strategy-option-handling:
  rebase: remove a couple of redundant strategy tests
  rebase -m: fix serialization of strategy options
  rebase -m: cleanup --strategy-option handling
  sequencer: use struct strvec to store merge strategy options
  rebase: stop reading and writing unnecessary strategy state
2023-04-17 18:05:13 -07:00
Junio C Hamano
66bf8f1943 Merge branch 'cm/branch-delete-error-message-update'
"git branch -d origin/master" would say "no such branch", but it is
likely a missed "-r" if refs/remotes/origin/master exists.  The
command has been taught to give such a hint in its error message.

* cm/branch-delete-error-message-update:
  branch: improve error log on branch not found by checking remotes refs
2023-04-17 18:05:12 -07:00
Junio C Hamano
9d8370d445 Merge branch 'tk/mergetool-gui-default-config'
"git mergetool" and "git difftool" learns a new configuration
guiDefault to optionally favor configured guitool over non-gui-tool
automatically when $DISPLAY is set.

* tk/mergetool-gui-default-config:
  mergetool: new config guiDefault supports auto-toggling gui by DISPLAY
2023-04-17 18:05:11 -07:00
Junio C Hamano
d47ee0a565 Merge branch 'sl/sparse-write-tree'
"git write-tree" learns to work better with sparse-index.

* sl/sparse-write-tree:
  write-tree: integrate with sparse index
2023-04-17 18:05:11 -07:00
Derrick Stolee
5a6072f631 fsck: validate .rev file header
While parsing a .rev file, we check the header information to be sure it
makes sense. This happens before doing any additional validation such as
a checksum or value check. In order to differentiate between a bad
header and a non-existent file, we need to update the API for loading a
reverse index.

Make load_pack_revindex_from_disk() non-static and specify that a
positive value means "the file does not exist" while other errors during
parsing are negative values. Since an invalid header prevents setting up
the structures we would use for further validations, we can stop at that
point.

The place where we can distinguish between a missing file and a corrupt
file is inside load_revindex_from_disk(), which is used both by pack
rev-indexes and multi-pack-index rev-indexes. Some tests in t5326
demonstrate that it is critical to take some conditions to allow
positive error signals.

Add tests that check the three header values.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-17 14:39:05 -07:00
Derrick Stolee
0d30feef3c fsck: create scaffolding for rev-index checks
The 'fsck' builtin checks many of Git's on-disk data structures, but
does not currently validate the pack rev-index files (a .rev file to
pair with a .pack and .idx file).

Before doing a more-involved check process, create the scaffolding
within builtin/fsck.c to have a new error type and add that error type
when the API method verify_pack_revindex() returns an error. That method
does nothing currently, but we will add checks to it in later changes.

For now, check that 'git fsck' succeeds without any errors in the normal
case. Future checks will be paired with tests that corrupt the .rev file
appropriately.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-17 14:39:04 -07:00
Jeff King
7ce4c8f752 v0 protocol: use size_t for capability length/offset
When parsing server capabilities, we use "int" to store lengths and
offsets. At first glance this seems like a spot where our parser may be
confused by integer overflow if somebody sent us a malicious response.

In practice these strings are all bounded by the 64k limit of a
pkt-line, so using "int" is OK. However, it makes the code simpler to
audit if they just use size_t everywhere. Note that because we take
these parameters as pointers, this also forces many callers to update
their declared types.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-14 15:08:13 -07:00
Patrick Steinhardt
d85cd18777 repack: disable writing bitmaps when doing a local repack
In order to write a bitmap, we need to have full coverage of all objects
that are about to be packed. In the traditional non-multi-pack-index
world this meant we need to do a full repack of all objects into a
single packfile. But in the new multi-pack-index world we can get away
with writing bitmaps when we have multiple packfiles as long as the
multi-pack-index covers all objects.

This is not always the case though. When asked to perform a repack of
local objects, only, then we cannot guarantee to have full coverage of
all objects regardless of whether we do a full repack or a repack with a
multi-pack-index. The end result is that writing the bitmap will fail in
both worlds:

    $ git multi-pack-index write --stdin-packs --bitmap <packfiles
    warning: Failed to write bitmap index. Packfile doesn't have full closure (object 1529341d78cf45377407369acb0f4ff2b5cdae42 is missing)
    error: could not write multi-pack bitmap

Now there are two different ways to fix this. The first one would be to
amend git-multi-pack-index(1) to disable writing bitmaps when we notice
that we don't have full object coverage.

    - We don't have enough information in git-multi-pack-index(1) in
      order to tell whether the local repository _should_ have full
      coverage. Because even when connected to an alternate object
      directory, it may be the case that we still have all objects
      around in the main object database.

    - git-multi-pack-index(1) is quite a low-level tool. Automatically
      disabling functionality that it was asked to provide does not feel
      like the right thing to do.

We can easily fix it at a higher level in git-repack(1) though. When
asked to only include local objects via `-l` and when connected to an
alternate object directory then we will override the user's ask and
disable writing bitmaps with a warning. This is similar to what we do in
git-pack-objects(1), where we also disable writing bitmaps in case we
omit an object from the pack.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-14 10:27:52 -07:00
Patrick Steinhardt
932c16c04b repack: honor -l when calculating pack geometry
When the user passes `-l` to git-repack(1), then they essentially ask us
to only repack objects part of the local object database while ignoring
any packfiles part of an alternate object database. And we in fact honor
this bit when doing a geometric repack as the resulting packfile will
only ever contain local objects.

What we're missing though is that we don't take locality of packfiles
into account when computing whether the geometric sequence is intact or
not. So even though we would only ever roll up local packfiles anyway,
we could end up trying to repack because of non-local packfiles. This
does not make much sense, and in the worst case it can cause us to try
and do the geometric repack over and over again because we're never able
to restore the geometric sequence.

Fix this bug by honoring whether the user has passed `-l`. If so, we
skip adding any non-local packfiles to the pack geometry.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-14 10:27:52 -07:00
Patrick Steinhardt
752b465c3c pack-objects: fix error when same packfile is included and excluded
When passing the same packfile both as included and excluded via the
`--stdin-packs` option, then we will return an error because the
excluded packfile cannot be found. This is because we will only set the
`util` pointer for the included packfile list if it was found, so that
we later die when we notice that it's in fact not set for the excluded
packfile list.

Fix this bug by always setting the `util` pointer for both the included
and excluded list entries.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-14 10:27:51 -07:00
Patrick Steinhardt
732194b5f2 pack-objects: fix error when packing same pack twice
When passed the same packfile twice via `--stdin-packs` we return an
error that the packfile supposedly was not found. This is because when
reading packs into the list of included or excluded packfiles, we will
happily re-add packfiles even if they are part of the lists already. And
while the list can now contain duplicates, we will only set the `util`
pointer of the first list entry to the `packed_git` structure. We notice
that at a later point when checking that all list entries have their
`util` pointer set and die with an error.

While this is kind of a nonsensical request, this scenario can be hit
when doing geometric repacks. When a repository is connected to an
alternate object directory and both have the exact same packfile then
both would get added to the geometric sequence. And when we then decide
to perform the repack, we will invoke git-pack-objects(1) with the same
packfile twice.

Fix this bug by removing any duplicates from both the included and
excluded packs.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-14 10:27:51 -07:00
Patrick Steinhardt
51861340f8 repack: fix generating multi-pack-index with only non-local packs
When writing the multi-pack-index with geometric repacking we will add
all packfiles to the index that are part of the geometric sequence. This
can potentially also include packfiles borrowed from an alternate object
directory. But given that a multi-pack-index can only ever include packs
that are part of the main object database this does not make much sense
whatsoever.

In the edge case where all packfiles are contained in the alternate
object database and the local repository has none itself this bug can
cause us to invoke git-multi-pack-index(1) with only non-local packfiles
that it ultimately cannot find. This causes it to return an error and
thus causes the geometric repack to fail.

Fix the code to skip non-local packfiles.

Co-authored-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-14 10:27:51 -07:00
Patrick Steinhardt
3d74a2337c repack: fix trying to use preferred pack in alternates
When doing a geometric repack with multi-pack-indices, then we ask
git-multi-pack-index(1) to use the largest packfile as the preferred
pack. It can happen though that the largest packfile is not part of the
main object database, but instead part of an alternate object database.
The result is that git-multi-pack-index(1) will not be able to find the
preferred pack and print a warning. It then falls back to use the first
packfile that the multi-pack-index shall reference.

Fix this bug by only considering packfiles as preferred pack that are
local. This is the right thing to do given that a multi-pack-index
should never reference packfiles borrowed from an alternate.

While at it, rename the function `get_largest_active_packfile()` to
`get_preferred_pack()` to better document its intent.

Helped-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-14 10:27:51 -07:00
Øystein Walle
aabfdc9514 branch, for-each-ref, tag: add option to omit empty lines
If the given format string expands to the empty string, a newline is
still printed. This makes using the output linewise more tedious. For
example, git update-ref --stdin does not accept empty lines.

Add options to "git branch", "git for-each-ref", and "git tag" to
not print these empty lines.  The default behavior remains the same.

Signed-off-by: Øystein Walle <oystwa@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-13 08:07:45 -07:00
Taylor Blau
9f7f10a282 t: invert GIT_TEST_WRITE_REV_INDEX
Back in e8c58f894b (t: support GIT_TEST_WRITE_REV_INDEX, 2021-01-25), we
added a test knob to conditionally enable writing a ".rev" file when
indexing a pack. At the time, this was used to ensure that the test
suite worked even when ".rev" files were written, which served as a
stress-test for the on-disk reverse index implementation.

Now that reading from on-disk ".rev" files is enabled by default, the
test knob `GIT_TEST_WRITE_REV_INDEX` no longer has any meaning.

We could get rid of the option entirely, but there would be no
convenient way to test Git when ".rev" files *aren't* in place.

Instead of getting rid of the option, invert its meaning to instead
disable writing ".rev" files, thereby running the test suite in a mode
where the reverse index is generated from scratch.

This ensures that, when GIT_TEST_NO_WRITE_REV_INDEX is set to some
spelling of "true", we are still running and exercising Git's behavior
when forced to generate reverse indexes from scratch. Do so by setting
it in the linux-TEST-vars CI run to ensure that we are maintaining good
coverage of this now-legacy code.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-13 07:55:46 -07:00
Taylor Blau
a8dd7e05b1 config: enable pack.writeReverseIndex by default
Back in e37d0b8730 (builtin/index-pack.c: write reverse indexes,
2021-01-25), Git learned how to read and write a pack's reverse index
from a file instead of in-memory.

A pack's reverse index is a mapping from pack position (that is, the
order that objects appear together in a ".pack")  to their position in
lexical order (that is, the order that objects are listed in an ".idx"
file).

Reverse indexes are consulted often during pack-objects, as well as
during auxiliary operations that require mapping between pack offsets,
pack order, and index index.

They are useful in GitHub's infrastructure, where we have seen a
dramatic increase in performance when writing ".rev" files[1]. In
particular:

  - an ~80% reduction in the time it takes to serve fetches on a popular
    repository, Homebrew/homebrew-core.

  - a ~60% reduction in the peak memory usage to serve fetches on that
    same repository.

  - a collective savings of ~35% in CPU time across all pack-objects
    invocations serving fetches across all repositories in a single
    datacenter.

Reverse indexes are also beneficial to end-users as well as forges. For
example, the time it takes to generate a pack containing the objects for
the 10 most recent commits in linux.git (representing a typical push) is
significantly faster when on-disk reverse indexes are available:

    $ { git rev-parse HEAD && printf '^' && git rev-parse HEAD~10 } >in
    $ hyperfine -L v false,true 'git.compile -c pack.readReverseIndex={v} pack-objects --delta-base-offset --revs --stdout <in >/dev/null'
    Benchmark 1: git.compile -c pack.readReverseIndex=false pack-objects --delta-base-offset --revs --stdout <in >/dev/null
      Time (mean ± σ):     543.0 ms ±  20.3 ms    [User: 616.2 ms, System: 58.8 ms]
      Range (min … max):   521.0 ms … 577.9 ms    10 runs

    Benchmark 2: git.compile -c pack.readReverseIndex=true pack-objects --delta-base-offset --revs --stdout <in >/dev/null
      Time (mean ± σ):     245.0 ms ±  11.4 ms    [User: 335.6 ms, System: 31.3 ms]
      Range (min … max):   226.0 ms … 259.6 ms    13 runs

    Summary
      'git.compile -c pack.readReverseIndex=true pack-objects --delta-base-offset --revs --stdout <in >/dev/null' ran
	2.22 ± 0.13 times faster than 'git.compile -c pack.readReverseIndex=false pack-objects --delta-base-offset --revs --stdout <in >/dev/null'

The same is true of writing a pack containing the objects for the 30
most-recent commits:

    $ { git rev-parse HEAD && printf '^' && git rev-parse HEAD~30 } >in
    $ hyperfine -L v false,true 'git.compile -c pack.readReverseIndex={v} pack-objects --delta-base-offset --revs --stdout <in >/dev/null'
    Benchmark 1: git.compile -c pack.readReverseIndex=false pack-objects --delta-base-offset --revs --stdout <in >/dev/null
      Time (mean ± σ):     866.5 ms ±  16.2 ms    [User: 1414.5 ms, System: 97.0 ms]
      Range (min … max):   839.3 ms … 886.9 ms    10 runs

    Benchmark 2: git.compile -c pack.readReverseIndex=true pack-objects --delta-base-offset --revs --stdout <in >/dev/null
      Time (mean ± σ):     581.6 ms ±  10.2 ms    [User: 1181.7 ms, System: 62.6 ms]
      Range (min … max):   567.5 ms … 599.3 ms    10 runs

    Summary
      'git.compile -c pack.readReverseIndex=true pack-objects --delta-base-offset --revs --stdout <in >/dev/null' ran
	1.49 ± 0.04 times faster than 'git.compile -c pack.readReverseIndex=false pack-objects --delta-base-offset --revs --stdout <in >/dev/null'

...and savings on trivial operations like computing the on-disk size of
a single (packed) object are even more dramatic:

    $ git rev-parse HEAD >in
    $ hyperfine -L v false,true 'git.compile -c pack.readReverseIndex={v} cat-file --batch-check="%(objectsize:disk)" <in'
    Benchmark 1: git.compile -c pack.readReverseIndex=false cat-file --batch-check="%(objectsize:disk)" <in
      Time (mean ± σ):     305.8 ms ±  11.4 ms    [User: 264.2 ms, System: 41.4 ms]
      Range (min … max):   290.3 ms … 331.1 ms    10 runs

    Benchmark 2: git.compile -c pack.readReverseIndex=true cat-file --batch-check="%(objectsize:disk)" <in
      Time (mean ± σ):       4.0 ms ±   0.3 ms    [User: 1.7 ms, System: 2.3 ms]
      Range (min … max):     1.6 ms …   4.6 ms    1155 runs

    Summary
      'git.compile -c pack.readReverseIndex=true cat-file --batch-check="%(objectsize:disk)" <in' ran
       76.96 ± 6.25 times faster than 'git.compile -c pack.readReverseIndex=false cat-file --batch-check="%(objectsize:disk)" <in'

In the more than two years since e37d0b8730 was merged, Git's
implementation of on-disk reverse indexes has been thoroughly tested,
both from users enabling `pack.writeReverseIndexes`, and from GitHub's
deployment of the feature. The latter has been running without incident
for more than two years.

This patch changes Git's behavior to write on-disk reverse indexes by
default when indexing a pack, which should make the above operations
faster for everybody's Git installation after a repack.

(The previous commit explains some potential drawbacks of using on-disk
reverse indexes in certain limited circumstances, that essentially boil
down to a trade-off between time to generate, and time to access. For
those limited cases, the `pack.readReverseIndex` escape hatch can be
used).

[1]: https://github.blog/2021-04-29-scaling-monorepo-maintenance/#reverse-indexes

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-13 07:55:46 -07:00
Junio C Hamano
96f4113ac0 Merge branch 'jc/clone-object-format-from-void'
"git clone" from an empty repository learned to propagate the
choice of the hash algorithm from the source repository to the
newly created repository.

* jc/clone-object-format-from-void:
  clone: propagate object-format when cloning from void
2023-04-11 13:49:13 -07:00
Junio C Hamano
d02343b599 Merge branch 'ws/sparse-check-rules'
"git sparse-checkout" command learns a debugging aid for the sparse
rule definitions.

* ws/sparse-check-rules:
  builtin/sparse-checkout: add check-rules command
  builtin/sparse-checkout: remove NEED_WORK_TREE flag
2023-04-11 13:49:12 -07:00
Elijah Newren
65156bb7ec treewide: remove double forward declaration of read_in_full
cache.h's nature of a dumping ground of includes prevented it from
being included in some compat/ files, forcing us into a workaround
of having a double forward declaration of the read_in_full() function
(see commit 14086b0a13 ("compat/pread.c: Add a forward declaration to
fix a warning", 2007-11-17)).  Now that we have moved functions like
read_in_full() from cache.h to wrapper.h, and wrapper.h isn't littered
with unrelated and scary #defines, get rid of the extra forward
declaration and just have compat/pread.c include wrapper.h.

Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:52:11 -07:00
Elijah Newren
ca4eed708d pager.h: move declarations for pager.c functions from cache.h
Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:52:10 -07:00
Elijah Newren
4e120823a3 editor: move editor-related functions and declarations into common file
cache.h and strbuf.[ch] had editor-related functions.  Move these into
editor.[ch].

Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:52:10 -07:00
Elijah Newren
87bed17907 object-file.h: move declarations for object-file.c functions from cache.h
Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:52:10 -07:00
Elijah Newren
d88dbaa718 git-zlib: move declarations for git-zlib functions from cache.h
Move functions from cache.h for zlib.c into a new header file.  Since
adding a "zlib.h" would cause issues with the real zlib, rename zlib.c
to git-zlib.c while we are at it.

Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:52:10 -07:00
Elijah Newren
dabab1d6e6 object-name.h: move declarations for object-name.c functions from cache.h
Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:52:09 -07:00
Elijah Newren
5bc07225e5 treewide: be explicit about dependence on mem-pool.h
Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:52:09 -07:00
Elijah Newren
6f2d743043 treewide: be explicit about dependence on oid-array.h
Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:52:09 -07:00
Elijah Newren
75f273d9b7 treewide: be explicit about dependence on pack-revindex.h
Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:52:09 -07:00
Elijah Newren
73359a9b43 treewide: be explicit about dependence on convert.h
Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:52:09 -07:00
Elijah Newren
6c6ddf92d5 treewide: be explicit about dependence on advice.h
Dozens of files made use of advice functions, without explicitly
including advice.h.  This made it more difficult to find which files
could remove a dependence on cache.h.  Make C files explicitly include
advice.h if they are using it.

Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:52:09 -07:00
Elijah Newren
74ea5c9574 treewide: be explicit about dependence on trace.h & trace2.h
Dozens of files made use of trace and trace2 functions, without
explicitly including trace.h or trace2.h.  This made it more difficult
to find which files could remove a dependence on cache.h.  Make C files
explicitly include trace.h or trace2.h if they are using them.

Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:52:08 -07:00
Glen Choo
4e33535ea9 clone: error specifically with --local and symlinked objects
6f054f9fb3 (builtin/clone.c: disallow --local clones with
symlinks, 2022-07-28) gives a good error message when "git clone
--local" fails when the repo to clone has symlinks in
"$GIT_DIR/objects". In bffc762f87 (dir-iterator: prevent top-level
symlinks without FOLLOW_SYMLINKS, 2023-01-24), we later extended this
restriction to the case where "$GIT_DIR/objects" is itself a symlink,
but we didn't update the error message then - bffc762f87's tests show
that we print a generic "failed to start iterator over" message.

This is exacerbated by the fact that Documentation/git-clone.txt
mentions neither restriction, so users are left wondering if this is
intentional behavior or not.

Fix this by adding a check to builtin/clone.c: when doing a local clone,
perform an extra check to see if "$GIT_DIR/objects" is a symlink, and if
so, assume that that was the reason for the failure and report the
relevant information. Ideally, dir_iterator_begin() would tell us that
the real failure reason is the presence of the symlink, but (as far as I
can tell) there isn't an appropriate errno value for that.

Also, update Documentation/git-clone.txt to reflect that this
restriction exists.

Signed-off-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-11 08:46:09 -07:00
Phillip Wood
4a8bc9860a rebase -m: cleanup --strategy-option handling
When handling "--strategy-option" rebase collects the commands into a
struct string_list, then concatenates them into a string, prepending "--"
to each one before splitting the string and removing the "--" prefix.
This is an artifact of the scripted rebase and the need to support
"rebase --preserve-merges". Now that "--preserve-merges" no-longer
exists we can cleanup the way the argument is handled.

The tests for a bad strategy option are adjusted now that
parse_strategy_opts() is no-longer called when starting a rebase. The
fact that it only errors out when running "git rebase --continue" is a
mixed blessing but the next commit will fix the root cause of the
parsing problem so lets not worry about that here.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-10 09:53:19 -07:00
Phillip Wood
fb60b9f37f sequencer: use struct strvec to store merge strategy options
The sequencer stores the merge strategy options in an array of strings
which allocated with ALLOC_GROW(). Using "struct strvec" avoids manually
managing the memory of that array and simplifies the code.

Aside from memory allocation the changes to the sequencer are largely
mechanical, changing xopts_nr to xopts.nr and xopts[i] to xopts.v[i]. A
new option parsing macro OPT_STRVEC() is also added to collect the
strategy options.  Hopefully this can be used to simplify the code in
builtin/merge.c in the future.

Note that there is a change of behavior to "git cherry-pick" and "git
revert" as passing “--no-strategy-option” will now clear any previous
strategy options whereas before this change it did nothing.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-10 09:53:19 -07:00
Phillip Wood
461434a013 rebase: stop reading and writing unnecessary strategy state
The state files for "--strategy" and "--strategy-option" are written and
read twice, once by builtin/rebase.c and then by sequencer.c. This is an
artifact of the scripted rebase and the need to support "rebase
--preserve-merges". Now that "--preserve-merges" no-longer exists we
only need to read and write these files in sequencer.c. This enables us
to remove a call to free() in read_strategy_opts() that was added by
f1f4ebf432 (sequencer.c: fix "opts->strategy" leak in
read_strategy_opts(), 2022-11-08) as this commit fixes the root cause of
that leak.

There is further scope for removing duplication in the reading and
writing of state files between builtin/rebase.c and sequencer.c but that
is left for a follow up series.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-10 09:53:19 -07:00
René Scharfe
c870de6502 get-tar-commit-id: use TYPEFLAG_GLOBAL_HEADER instead of magic value
Use the same macro in the archive reader code as on the writer side in
archive-tar.c to document the connection.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-10 09:22:34 -07:00