Commit Graph

9581 Commits

Author SHA1 Message Date
8380dcd700 oid_pos(): access table through const pointers
When we are looking up an oid in an array, we obviously don't need to
write to the array. Let's mark it as const in the function interfaces,
as well as in the local variables we use to derference the void pointer
(note a few cases use pointers-to-pointers, so we mark everything
const).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-28 12:03:26 -08:00
45ee13b942 hash_pos(): convert to oid_pos()
All of our callers are actually looking up an object_id, not a bare
hash. Likewise, the arrays they are looking in are actual arrays of
object_id (not just raw bytes of hashes, as we might find in a pack
.idx; those are handled by bsearch_hash()).

Using an object_id gives us more type safety, and makes the callers
slightly shorter. It also gets rid of the word "sha1" from several
access functions, though we could obviously also rename those with
s/sha1/hash/.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-28 12:02:39 -08:00
679b5916cd range-diff/format-patch: refactor check for commit range
Currently, when called with exactly two arguments, `git range-diff`
tests for a literal `..` in each of the two. Likewise, the argument
provided via `--range-diff` to `git format-patch` is checked in the same
manner.

However, `<commit>^!` is a perfectly valid commit range, equivalent to
`<commit>^..<commit>` according to the `SPECIFYING RANGES` section of
gitrevisions[7].

In preparation for allowing more sophisticated ways to specify commit
ranges, let's refactor the check into its own function.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-27 22:01:49 -08:00
15c9649730 grep/log: remove hidden --debug and --grep-debug options
Remove the hidden "grep --debug" and "log --grep-debug" options added
in 17bf35a3c7 (grep: teach --debug option to dump the parse tree,
2012-09-13).

At the time these options seem to have been intended to go along with
a documentation discussion and to help the author of relevant tests to
perform ad-hoc debugging on them[1].

Reasons to want this gone:

 1. They were never documented, and the only (rather trivial) use of
    them in our own codebase for testing is something I removed back
    in e01b4dab01 (grep: change non-ASCII -i test to stop using
    --debug, 2017-05-20).

 2. Googling around doesn't show any in-the-wild uses I could dig up,
    and on the Git ML the only mentions after the original discussion
    seem to have been when they came up in unrelated diff contexts, or
    that test commit of mine.

 3. An exception to that is c581e4a749 (grep: under --debug, show
    whether PCRE JIT is enabled, 2019-08-18) where we added the
    ability to dump out when PCREv2 has the JIT in effect.

    The combination of that and my earlier b65abcafc7 (grep: use PCRE
    v2 for optimized fixed-string search, 2019-07-01) means Git prints
    this out in its most common in-the-wild configuration:

        $ git log  --grep-debug --grep=foo --grep=bar --grep=baz --all-match
        pcre2_jit_on=1
        pcre2_jit_on=1
        pcre2_jit_on=1
        [all-match]
        (or
         pattern_body<body>foo
         (or
          pattern_body<body>bar
          pattern_body<body>baz
         )
        )

        $ git grep --debug \( -e foo --and -e bar \) --or -e baz
        pcre2_jit_on=1
        pcre2_jit_on=1
        pcre2_jit_on=1
        (or
         (and
          patternfoo
          patternbar
         )
         patternbaz
        )

I.e. for each pattern we're considering for the and/or/--all-match
etc. debugging we'll now diligently spew out another identical line
saying whether the PCREv2 JIT is on or not.

I think that nobody's complained about that rather glaringly obviously
bad output says something about how much this is used, i.e. it's
not.

The need for this debugging aid for the composed grep/log patterns
seems to have passed, and the desire to dump the JIT config seems to
have been another one-off around the time we had JIT-related issues on
the PCREv2 codepath. That the original author of this debugging
facility seemingly hasn't noticed the bad output since then[2] is
probably some indicator.

1. https://lore.kernel.org/git/cover.1347615361.git.git@drmicha.warpmail.net/
2. https://lore.kernel.org/git/xmqqk1b8x0ac.fsf@gitster-ct.c.googlers.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-26 11:36:20 -08:00
e8c58f894b t: support GIT_TEST_WRITE_REV_INDEX
Add a new option that unconditionally enables the pack.writeReverseIndex
setting in order to run the whole test suite in a mode that generates
on-disk reverse indexes. Additionally, enable this mode in the second
run of tests under linux-gcc in 'ci/run-build-and-tests.sh'.

Once on-disk reverse indexes are proven out over several releases, we
can change the default value of that configuration to 'true', and drop
this patch.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-25 18:32:44 -08:00
c97733435a builtin/pack-objects.c: respect 'pack.writeReverseIndex'
Now that we have an implementation that can write the new reverse index
format, enable writing a .rev file in 'git pack-objects' by consulting
the pack.writeReverseIndex configuration variable.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-25 18:32:43 -08:00
e37d0b8730 builtin/index-pack.c: write reverse indexes
Teach 'git index-pack' to optionally write and verify reverse index with
'--[no-]rev-index', as well as respecting the 'pack.writeReverseIndex'
configuration option.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-25 18:32:43 -08:00
84d544943c builtin/index-pack.c: allow stripping arbitrary extensions
To derive the filename for a .idx file, 'git index-pack' uses
derive_filename() to strip the '.pack' suffix and add the new suffix.

Prepare for stripping off suffixes other than '.pack' by making the
suffix to strip a parameter of derive_filename(). In order to make this
consistent with the "suffix" parameter which does not begin with a ".",
an additional check in derive_filename.

Suggested-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-25 18:32:43 -08:00
2f4ba2a867 packfile: prepare for the existence of '*.rev' files
Specify the format of the on-disk reverse index 'pack-*.rev' file, as
well as prepare the code for the existence of such files.

The reverse index maps from pack relative positions (i.e., an index into
the array of object which is sorted by their offsets within the
packfile) to their position within the 'pack-*.idx' file. Today, this is
done by building up a list of (off_t, uint32_t) tuples for each object
(the off_t corresponding to that object's offset, and the uint32_t
corresponding to its position in the index). To convert between pack and
index position quickly, this array of tuples is radix sorted based on
its offset.

This has two major drawbacks:

First, the in-memory cost scales linearly with the number of objects in
a pack.  Each 'struct revindex_entry' is sizeof(off_t) +
sizeof(uint32_t) + padding bytes for a total of 16.

To observe this, force Git to load the reverse index by, for e.g.,
running 'git cat-file --batch-check="%(objectsize:disk)"'. When asking
for a single object in a fresh clone of the kernel, Git needs to
allocate 120+ MB of memory in order to hold the reverse index in memory.

Second, the cost to sort also scales with the size of the pack.
Luckily, this is a linear function since 'load_pack_revindex()' uses a
radix sort, but this cost still must be paid once per pack per process.

As an example, it takes ~60x longer to print the _size_ of an object as
it does to print that entire object's _contents_:

  Benchmark #1: git.compile cat-file --batch <obj
    Time (mean ± σ):       3.4 ms ±   0.1 ms    [User: 3.3 ms, System: 2.1 ms]
    Range (min … max):     3.2 ms …   3.7 ms    726 runs

  Benchmark #2: git.compile cat-file --batch-check="%(objectsize:disk)" <obj
    Time (mean ± σ):     210.3 ms ±   8.9 ms    [User: 188.2 ms, System: 23.2 ms]
    Range (min … max):   193.7 ms … 224.4 ms    13 runs

Instead, avoid computing and sorting the revindex once per process by
writing it to a file when the pack itself is generated.

The format is relatively straightforward. It contains an array of
uint32_t's, the length of which is equal to the number of objects in the
pack.  The ith entry in this table contains the index position of the
ith object in the pack, where "ith object in the pack" is determined by
pack offset.

One thing that the on-disk format does _not_ contain is the full (up to)
eight-byte offset corresponding to each object. This is something that
the in-memory revindex contains (it stores an off_t in 'struct
revindex_entry' along with the same uint32_t that the on-disk format
has). Omit it in the on-disk format, since knowing the index position
for some object is sufficient to get a constant-time lookup in the
pack-*.idx file to ask for an object's offset within the pack.

This trades off between the on-disk size of the 'pack-*.rev' file for
runtime to chase down the offset for some object. Even though the lookup
is constant time, the constant is heavier, since it can potentially
involve two pointer walks in v2 indexes (one to access the 4-byte offset
table, and potentially a second to access the double wide offset table).

Consider trying to map an object's pack offset to a relative position
within that pack. In a cold-cache scenario, more page faults occur while
switching between binary searching through the reverse index and
searching through the *.idx file for an object's offset. Sure enough,
with a cold cache (writing '3' into '/proc/sys/vm/drop_caches' after
'sync'ing), printing out the entire object's contents is still
marginally faster than printing its size:

  Benchmark #1: git.compile cat-file --batch-check="%(objectsize:disk)" <obj >/dev/null
    Time (mean ± σ):      22.6 ms ±   0.5 ms    [User: 2.4 ms, System: 7.9 ms]
    Range (min … max):    21.4 ms …  23.5 ms    41 runs

  Benchmark #2: git.compile cat-file --batch <obj >/dev/null
    Time (mean ± σ):      17.2 ms ±   0.7 ms    [User: 2.8 ms, System: 5.5 ms]
    Range (min … max):    15.6 ms …  18.2 ms    45 runs

(Numbers taken in the kernel after cheating and using the next patch to
generate a reverse index). There are a couple of approaches to improve
cold cache performance not pursued here:

  - We could include the object offsets in the reverse index format.
    Predictably, this does result in fewer page faults, but it triples
    the size of the file, while simultaneously duplicating a ton of data
    already available in the .idx file. (This was the original way I
    implemented the format, and it did show
    `--batch-check='%(objectsize:disk)'` winning out against `--batch`.)

    On the other hand, this increase in size also results in a large
    block-cache footprint, which could potentially hurt other workloads.

  - We could store the mapping from pack to index position in more
    cache-friendly way, like constructing a binary search tree from the
    table and writing the values in breadth-first order. This would
    result in much better locality, but the price you pay is trading
    O(1) lookup in 'pack_pos_to_index()' for an O(log n) one (since you
    can no longer directly index the table).

So, neither of these approaches are taken here. (Thankfully, the format
is versioned, so we are free to pursue these in the future.) But, cold
cache performance likely isn't interesting outside of one-off cases like
asking for the size of an object directly. In real-world usage, Git is
often performing many operations in the revindex (i.e., asking about
many objects rather than a single one).

The trade-off is worth it, since we will avoid the vast majority of the
cost of generating the revindex that the extra pointer chase will look
like noise in the following patch's benchmarks.

This patch describes the format and prepares callers (like in
pack-revindex.c) to be able to read *.rev files once they exist. An
implementation of the writer will appear in the next patch, and callers
will gradually begin to start using the writer in the patches that
follow after that.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-25 18:32:43 -08:00
bcaaf972e6 Merge branch 'tb/pack-revindex-api'
Abstract accesses to in-core revindex that allows enumerating
objects stored in a packfile in the order they appear in the pack,
in preparation for introducing an on-disk precomputed revindex.

* tb/pack-revindex-api: (21 commits)
  for_each_object_in_pack(): clarify pack vs index ordering
  pack-revindex.c: avoid direct revindex access in 'offset_to_pack_pos()'
  pack-revindex: hide the definition of 'revindex_entry'
  pack-revindex: remove unused 'find_revindex_position()'
  pack-revindex: remove unused 'find_pack_revindex()'
  builtin/gc.c: guess the size of the revindex
  for_each_object_in_pack(): convert to new revindex API
  unpack_entry(): convert to new revindex API
  packed_object_info(): convert to new revindex API
  retry_bad_packed_offset(): convert to new revindex API
  get_delta_base_oid(): convert to new revindex API
  rebuild_existing_bitmaps(): convert to new revindex API
  try_partial_reuse(): convert to new revindex API
  get_size_by_pos(): convert to new revindex API
  show_objects_for_type(): convert to new revindex API
  bitmap_position_packfile(): convert to new revindex API
  check_object(): convert to new revindex API
  write_reused_pack_verbatim(): convert to new revindex API
  write_reused_pack_one(): convert to new revindex API
  write_reuse_object(): convert to new revindex API
  ...
2021-01-25 14:19:20 -08:00
7eefa1349b Merge branch 'cc/write-promisor-file'
A bit of code refactoring.

* cc/write-promisor-file:
  pack-write: die on error in write_promisor_file()
  fetch-pack: refactor writing promisor file
  fetch-pack: rename helper to create_promisor_file()
2021-01-25 14:19:19 -08:00
42342b3ee6 Merge branch 'ab/mailmap'
Clean-up docs, codepaths and tests around mailmap.

* ab/mailmap: (22 commits)
  shortlog: remove unused(?) "repo-abbrev" feature
  mailmap doc + tests: document and test for case-insensitivity
  mailmap tests: add tests for empty "<>" syntax
  mailmap tests: add tests for whitespace syntax
  mailmap tests: add a test for comment syntax
  mailmap doc + tests: add better examples & test them
  tests: refactor a few tests to use "test_commit --append"
  test-lib functions: add an --append option to test_commit
  test-lib functions: add --author support to test_commit
  test-lib functions: document arguments to test_commit
  test-lib functions: expand "test_commit" comment template
  mailmap: test for silent exiting on missing file/blob
  mailmap tests: get rid of overly complex blame fuzzing
  mailmap tests: add a test for "not a blob" error
  mailmap tests: remove redundant entry in test
  mailmap tests: improve --stdin tests
  mailmap tests: modernize syntax & test idioms
  mailmap tests: use our preferred whitespace syntax
  mailmap doc: start by mentioning the comment syntax
  check-mailmap doc: note config options
  ...
2021-01-25 14:19:19 -08:00
60ecad090d Merge branch 'ps/fetch-atomic'
"git fetch" learns to treat ref updates atomically in all-or-none
fashion, just like "git push" does, with the new "--atomic" option.

* ps/fetch-atomic:
  fetch: implement support for atomic reference updates
  fetch: allow passing a transaction to `s_update_ref()`
  fetch: refactor `s_update_ref` to use common exit path
  fetch: use strbuf to format FETCH_HEAD updates
  fetch: extract writing to FETCH_HEAD
2021-01-25 14:19:19 -08:00
dfcd905069 Merge branch 'jc/deprecate-pack-redundant'
Warn loudly when the "pack-redundant" command, which has been left
stale with almost unusable performance issues, gets used, as we no
longer want to recommend its use (instead just "repack -d" instead).

* jc/deprecate-pack-redundant:
  pack-redundant: gauge the usage before proposing its removal
2021-01-25 14:19:18 -08:00
9e409d7e07 Merge branch 'ab/branch-sort'
The implementation of "git branch --sort" wrt the detached HEAD
display has always been hacky, which has been cleaned up.

* ab/branch-sort:
  branch: show "HEAD detached" first under reverse sort
  branch: sort detached HEAD based on a flag
  ref-filter: move ref_sorting flags to a bitfield
  ref-filter: move "cmp_fn" assignment into "else if" arm
  ref-filter: add braces to if/else if/else chain
  branch tests: add to --sort tests
  branch: change "--local" to "--list" in comment
2021-01-25 14:19:17 -08:00
58e2ce9112 Merge branch 'ma/more-opaque-lock-file'
Code clean-up.

* ma/more-opaque-lock-file:
  read-cache: try not to peek into `struct {lock_,temp}file`
  refs/files-backend: don't peek into `struct lock_file`
  midx: don't peek into `struct lock_file`
  commit-graph: don't peek into `struct lock_file`
  builtin/gc: don't peek into `struct lock_file`
2021-01-25 14:19:17 -08:00
c7d6d419b0 Merge branch 'ab/mktag'
"git mktag" validates its input using its own rules before writing
a tag object---it has been updated to share the logic with "git
fsck".

* ab/mktag: (23 commits)
  mktag: add a --[no-]strict option
  mktag: mark strings for translation
  mktag: convert to parse-options
  mktag: allow omitting the header/body \n separator
  mktag: allow turning off fsck.extraHeaderEntry
  fsck: make fsck_config() re-usable
  mktag: use fsck instead of custom verify_tag()
  mktag: use puts(str) instead of printf("%s\n", str)
  mktag: remove redundant braces in one-line body "if"
  mktag: use default strbuf_read() hint
  mktag tests: test verify_object() with replaced objects
  mktag tests: improve verify_object() test coverage
  mktag tests: test "hash-object" compatibility
  mktag tests: stress test whitespace handling
  mktag tests: run "fsck" after creating "mytag"
  mktag tests: don't create "mytag" twice
  mktag tests: don't redirect stderr to a file needlessly
  mktag tests: remove needless SHA-1 hardcoding
  mktag tests: use "test_commit" helper
  mktag tests: don't needlessly use a subshell
  ...
2021-01-25 14:19:17 -08:00
dd23022acb sparse-checkout: load sparse-checkout patterns
A future feature will want to load the sparse-checkout patterns into a
pattern_list, but the current mechanism to do so is a bit complicated.
This is made difficult due to needing to find the sparse-checkout file
in different ways throughout the codebase.

The logic implemented in the new get_sparse_checkout_patterns() was
duplicated in populate_from_existing_patterns() in unpack-trees.c. Use
the new method instead, keeping the logic around handling the struct
unpack_trees_options.

The callers to get_sparse_checkout_filename() in
builtin/sparse-checkout.c manipulate the sparse-checkout file directly,
so it is not appropriate to replace logic in that file with
get_sparse_checkout_patterns().

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-23 17:14:07 -08:00
fb0882648e cache-tree: clean up cache_tree_update()
Make the method safer by allocating a cache_tree member for the given
index_state if it is not already present. This is preferrable to a
BUG() statement or returning with an error because future callers will
want to populate an empty cache-tree using this method.

Callers can also remove their conditional allocations of cache_tree.

Also drop local variables that can be found directly from the 'istate'
parameter.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-23 17:14:07 -08:00
93a7d9835f ls-files.c: add --deduplicate option
During a merge conflict, the name of a file may appear multiple
times in "git ls-files" output, once for each stage.  If you use
both `--delete` and `--modify` at the same time, the output may
mention a deleted file twice.

When none of the '-t', '-u', or '-s' options is in use, these
duplicate entries do not add much value to the output.

Introduce a new '--deduplicate' option to suppress them.

Signed-off-by: ZheNing Hu <adlternative@gmail.com>
[jc: extended doc and rewritten commit log]
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-23 11:48:20 -08:00
ed644d1666 ls_files.c: consolidate two for loops into one
This will make it easier to show only one entry per filename in the
next step.

Signed-off-by: ZheNing Hu <adlternative@gmail.com>
[jc: corrected the log message]
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-23 11:48:20 -08:00
f1c462ea41 ls_files.c: bugfix for --deleted and --modified
This situation may occur in the original code: lstat() failed
but we use `&st` to feed ie_modified() later.

Therefore, we can directly execute show_ce without the judgment of
ie_modified() when lstat() has failed.

Signed-off-by: ZheNing Hu <adlternative@gmail.com>
[jc: fixed misindented code]
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-23 11:48:11 -08:00
be18153b97 builtin/pack-objects.c: avoid iterating all refs
In git-pack-objects, we iterate over all the tags if the --include-tag
option is passed on the command line. For some reason this uses
for_each_ref which is expensive if the repo has many refs. We should
use for_each_tag_ref instead.

Because the add_ref_tag callback will now only visit tags we
simplified it a bit.

The motivation for this change is that we observed performance issues
with a repository on gitlab.com that has 500,000 refs but only 2,000
tags. The fetch traffic on that repo is dominated by CI, and when we
changed CI to fetch with 'git fetch --no-tags' we saw a dramatic
change in the CPU profile of git-pack-objects. This lead us to this
particular ref walk. More details in:
https://gitlab.com/gitlab-com/gl-infra/scalability/-/issues/746#note_483546598

Signed-off-by: Jacob Vosmaer <jacob@gitlab.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-22 17:27:42 -08:00
8198907795 use delete_refs when deleting tags or branches
'git tag -d' accepts one or more tag refs to delete, but each deletion
is done by calling `delete_ref` on each argv. This is very slow when
removing from packed refs. Use delete_refs instead so all the removals
can be done inside a single transaction with a single update.

Do the same for 'git branch -d'.

Since delete_refs performs all the packed-refs delete operations
inside a single transaction, if any of the deletes fail then all
them will be skipped. In practice, none of them should fail since
we verify the hash of each one before calling delete_refs, but some
network error or odd permissions problem could have different results
after this change.

Also, since the file-backed deletions are not performed in the same
transaction, those could succeed even when the packed-refs transaction
fails.

After deleting branches, remove the branch config only if the branch
ref was removed and was not subsequently added back in.

A manual test deleting 24,000 tags took about 30 minutes using
delete_ref.  It takes about 5 seconds using delete_refs.

Acked-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Phil Hord <phil.hord@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-21 16:05:05 -08:00
36a317929b refs: switch peel_ref() to peel_iterated_oid()
The peel_ref() interface is confusing and error-prone:

  - it's typically used by ref iteration callbacks that have both a
    refname and oid. But since they pass only the refname, we may load
    the ref value from the filesystem again. This is inefficient, but
    also means we are open to a race if somebody simultaneously updates
    the ref. E.g., this:

      int some_ref_cb(const char *refname, const struct object_id *oid, ...)
      {
              if (!peel_ref(refname, &peeled))
                      printf("%s peels to %s",
                             oid_to_hex(oid), oid_to_hex(&peeled);
      }

    could print nonsense. It is correct to say "refname peels to..."
    (you may see the "before" value or the "after" value, either of
    which is consistent), but mentioning both oids may be mixing
    before/after values.

    Worse, whether this is possible depends on whether the optimization
    to read from the current iterator value kicks in. So it is actually
    not possible with:

      for_each_ref(some_ref_cb);

    but it _is_ possible with:

      head_ref(some_ref_cb);

    which does not use the iterator mechanism (though in practice, HEAD
    should never peel to anything, so this may not be triggerable).

  - it must take a fully-qualified refname for the read_ref_full() code
    path to work. Yet we routinely pass it partial refnames from
    callbacks to for_each_tag_ref(), etc. This happens to work when
    iterating because there we do not call read_ref_full() at all, and
    only use the passed refname to check if it is the same as the
    iterator. But the requirements for the function parameters are quite
    unclear.

Instead of taking a refname, let's instead take an oid. That fixes both
problems. It's a little funny for a "ref" function not to involve refs
at all. The key thing is that it's optimizing under the hood based on
having access to the ref iterator. So let's change the name to make it
clear why you'd want this function versus just peel_object().

There are two other directions I considered but rejected:

  - we could pass the peel information into the each_ref_fn callback.
    However, we don't know if the caller actually wants it or not. For
    packed-refs, providing it is essentially free. But for loose refs,
    we actually have to peel the object, which would be wasteful in most
    cases. We could likewise pass in a flag to the callback indicating
    whether the peeled information is known, but that complicates those
    callbacks, as they then have to decide whether to manually peel
    themselves. Plus it requires changing the interface of every
    callback, whether they care about peeling or not, and there are many
    of them.

  - we could make a function to return the peeled value of the current
    iterated ref (computing it if necessary), and BUG() otherwise. I.e.:

      int peel_current_iterated_ref(struct object_id *out);

    Each of the current callers is an each_ref_fn callback, so they'd
    mostly be happy. But:

      - we use those callbacks with functions like head_ref(), which do
        not use the iteration code. So we'd need to handle the fallback
        case there, anyway.

      - it's possible that a caller would want to call into generic code
        that sometimes is used during iteration and sometimes not. This
        encapsulates the logic to do the fast thing when possible, and
        fallback when necessary.

The implementation is mostly obvious, but I want to call out a few
things in the patch:

  - the test-tool coverage for peel_ref() is now meaningless, as it all
    collapses to a single peel_object() call (arguably they were pretty
    uninteresting before; the tricky part of that function is the
    fast-path we see during iteration, but these calls didn't trigger
    that). I've just dropped it entirely, though note that some other
    tests relied on the tags we created; I've moved that creation to the
    tests where it matters.

  - we no longer need to take a ref_store parameter, since we'd never
    look up a ref now. We do still rely on a global "current iterator"
    variable which _could_ be kept per-ref-store. But in practice this
    is only useful if there are multiple recursive iterations, at which
    point the more appropriate solution is probably a stack of
    iterators. No caller used the actual ref-store parameter anyway
    (they all call the wrapper that passes the_repository).

  - the original only kicked in the optimization when the "refname"
    pointer matched (i.e., not string comparison). We do likewise with
    the "oid" parameter here, but fall back to doing an actual oideq()
    call. This in theory lets us kick in the optimization more often,
    though in practice no current caller cares. It should never be
    wrong, though (peeling is a property of an object, so two refs
    pointing to the same object would peel identically).

  - the original took care not to touch the peeled out-parameter unless
    we found something to put in it. But no caller cares about this, and
    anyway, it is enforced by peel_object() itself (and even in the
    optimized iterator case, that's where we eventually end up). We can
    shorten the code and avoid an extra copy by just passing the
    out-parameter through the stack.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-21 15:51:31 -08:00
96eaffebbf maintenance: set log.excludeDecoration durin prefetch
The 'prefetch' task fetches refs from all remotes and places them in the
refs/prefetch/<remote>/ refspace. As this task is intended to run in the
background, this allows users to keep their local data very close to the
remote servers' data while not updating the users' understanding of the
remote refs in refs/remotes/<remote>/.

However, this can clutter 'git log' decorations with copies of the refs
with the full name 'refs/prefetch/<remote>/<branch>'.

The log.excludeDecoration config option was added in a6be5e67 (log: add
log.excludeDecoration config option, 2020-05-16) for exactly this
purpose.

Ensure we set this only for users that would benefit from it by
assigning it at the beginning of the prefetch task. Other alternatives
would be during 'git maintenance register' or 'git maintenance start',
but those might assign the config even when the prefetch task is
disabled by existing config. Further, users could run 'git maintenance
run --task=prefetch' using their own scripting or scheduling. This
provides the best coverage to automatically update the config when
valuable.

It is improbable, but possible, that users might want to run the
prefetch task _and_ see these refs in their log decorations. This seems
incredibly unlikely to me, but users can always opt-in on a
command-by-command basis using --decorate-refs=refs/prefetch/.

Test that this works in a few cases. In particular, ensure that our
assignment of log.excludeDecoration=refs/prefetch/ is additive to other
existing exclusions. Further, ensure we do not add multiple copies in
multiple runs.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-20 18:46:22 -08:00
aa08688362 Merge branch 'ds/for-each-repo-noopfix'
"git for-each-repo --config=<var> <cmd>" should not run <cmd> for
any repository when the configuration variable <var> is not defined
even once.

* ds/for-each-repo-noopfix:
  for-each-repo: do nothing on empty config
2021-01-15 21:48:46 -08:00
b2ace18759 Merge branch 'ds/maintenance-part-4'
Follow-up on the "maintenance part-3" which introduced scheduled
maintenance tasks to support platforms whose native scheduling
methods are not 'cron'.

* ds/maintenance-part-4:
  maintenance: use Windows scheduled tasks
  maintenance: use launchctl on macOS
  maintenance: include 'cron' details in docs
  maintenance: extract platform-specific scheduling
2021-01-15 21:48:45 -08:00
62fb47a4d3 Merge branch 'en/stash-apply-sparse-checkout'
"git stash" did not work well in a sparsely checked out working
tree.

* en/stash-apply-sparse-checkout:
  stash: fix stash application in sparse-checkouts
  stash: remove unnecessary process forking
  t7012: add a testcase demonstrating stash apply bugs in sparse checkouts
2021-01-15 15:20:29 -08:00
2ce8de6bf9 Merge branch 'zh/arg-help-format'
Clean up option descriptions in "git cmd --help".

* zh/arg-help-format:
  builtin/*: update usage format
  parse-options: format argh like error messages
2021-01-15 15:20:29 -08:00
df26861c56 Merge branch 'rs/rebase-commit-validation'
Diagnose command line error of "git rebase" early.

* rs/rebase-commit-validation:
  rebase: verify commit parameter
2021-01-15 15:20:29 -08:00
8b327f1784 Merge branch 'ma/sha1-is-a-hash'
Retire more names with "sha1" in it.

* ma/sha1-is-a-hash:
  hash-lookup: rename from sha1-lookup
  sha1-lookup: rename `sha1_pos()` as `hash_pos()`
  object-file.c: rename from sha1-file.c
  object-name.c: rename from sha1-name.c
2021-01-15 15:20:29 -08:00
9ba366f12b Merge branch 'bc/rev-parse-path-format'
"git rev-parse" can be explicitly told to give output as absolute
or relative path with the `--path-format=(absolute|relative)` option.

* bc/rev-parse-path-format:
  rev-parse: add option for absolute or relative path formatting
  abspath: add a function to resolve paths with missing components
2021-01-15 15:20:28 -08:00
2891b434ac builtin/gc.c: guess the size of the revindex
'estimate_repack_memory()' takes into account the amount of memory
required to load the reverse index in memory by multiplying the assumed
number of objects by the size of the 'revindex_entry' struct.

Prepare for hiding the definition of 'struct revindex_entry' by removing
a 'sizeof()' of that type from outside of pack-revindex.c. Instead,
guess that one off_t and one uint32_t are required per object. Strictly
speaking, this is a worse guess than asking for 'sizeof(struct
revindex_entry)' directly, since the true size of this struct is 16
bytes with padding on the end of the struct in order to align the offset
field.

But, this is an approximation anyway, and it does remove a use of the
'struct revindex_entry' from outside of pack-revindex internals.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-13 21:53:47 -08:00
eb3fd99efd check_object(): convert to new revindex API
Replace direct accesses to the revindex with calls to
'offset_to_pack_pos()' and 'pack_pos_to_index()'.

Since this caller already had some error checking (it can jump to the
'give_up' label if it encounters an error), we can easily check whether
or not the provided offset points to an object in the given pack. This
error checking existed prior to this patch, too, since the caller checks
whether the return value from 'find_pack_revindex()' was NULL or not.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-13 21:53:45 -08:00
6a5c10c45f write_reused_pack_verbatim(): convert to new revindex API
Replace a direct access to the revindex array with
'pack_pos_to_offset()'.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-13 21:53:45 -08:00
66cbd3e2fb write_reused_pack_one(): convert to new revindex API
Replace direct revindex accesses with calls to 'pack_pos_to_offset()'
and 'pack_pos_to_index()'.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-13 21:53:45 -08:00
952fc6870d write_reuse_object(): convert to new revindex API
First replace 'find_pack_revindex()' with its replacement
'offset_to_pack_pos()'. This prevents any bogus OFS_DELTA that may make
its way through until 'write_reuse_object()' from causing a bad memory
read (if 'revidx' is 'NULL')

Next, replace a direct access of '->nr' with the wrapper function
'pack_pos_to_index()'.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-13 21:53:45 -08:00
33add2ad7d fetch-pack: refactor writing promisor file
Let's replace the 2 different pieces of code that write a
promisor file in 'builtin/repack.c' and 'fetch-pack.c'
with a new function called 'write_promisor_file()' in
'pack-write.c' and 'pack.h'.

This might also help us in the future, if we want to put
back the ref names and associated hashes that were in
the promisor files we are repacking in 'builtin/repack.c'
as suggested by a NEEDSWORK comment just above the code
we are refactoring.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-12 16:01:07 -08:00
4e168333a8 shortlog: remove unused(?) "repo-abbrev" feature
Remove support for the magical "repo-abbrev" comment in .mailmap
files. This was added to .mailmap parsing in [1], as a generalized
feature of the git-shortlog Perl script added earlier in [2].

There was no documentation or tests for this feature, and I don't
think it's used in practice anymore.

What it did was to allow you to specify a single string to be
search-replaced with "/.../" in the .mailmap file. E.g. for
linux.git's current .mailmap:

    git archive --remote=git@gitlab.com:linux-kernel/linux.git \
        HEAD -- .mailmap | grep -a repo-abbrev
    # repo-abbrev: /pub/scm/linux/kernel/git/

Then when running e.g.:

    git shortlog --merges --author=Linus -1 v5.10-rc7..v5.10 | grep Merge

We'd emit (the [...] is mine):

      Merge tag [...]git://git.kernel.org/.../tip/tip

But will now emit:

      Merge tag [...]git.kernel.org/pub/scm/linux/kernel/git/tip/tip

I think at this point this is just a historical artifact we can get
rid of. It was initially meant for Linus's own use when we integrated
the Perl script[2], but since then it seems he's stopped using it.

Digging through Linus's release announcements on the LKML[3] the last
release I can find that made use of this output is Linux 2.6.25-rc6
back in March 2008[4]. Later on Linus started using --no-merges[5],
and nowadays seems to prefer some custom not-quite-shortlog format of
merges from lieutenants[6].

You will still see it on linux.git if you run "git shortlog" manually
yourself with --merges, with this removed you can still get the same
output with:

    git log --pretty=fuller v5.10-rc7..v5.10 |
    sed 's!/pub/scm/linux/kernel/git/!/.../!g' |
    git shortlog

Arguably we should do the same for the search-replacing of "[PATCH]"
at the beginning with "". That seems to be another relic of a bygone
era when linux.git patches would have their E-Mail subject lines
applied as-is by "git am" or whatever. But we documented that feature
in "git-shortlog(1)", and it seems more widely applicable than
something purely kernel-specific.

1. 7595e2ee6e (git-shortlog: make common repository prefix
   configurable with .mailmap, 2006-11-25)
2. fa375c7f1b (Add git-shortlog perl script, 2005-06-04)
3. https://lore.kernel.org/lkml/
4. https://lore.kernel.org/lkml/alpine.LFD.1.00.0803161651350.3020@woody.linux-foundation.org/
5. https://lore.kernel.org/lkml/BANLkTinrbh7Xi27an3uY7pDWrNKhJRYmEA@mail.gmail.com/
6. https://lore.kernel.org/lkml/CAHk-=wg1+kf1AVzXA-RQX0zjM6t9J2Kay9xyuNqcFHWV-y5ZYw@mail.gmail.com/

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-12 14:04:42 -08:00
c7b190dabd fetch: implement support for atomic reference updates
When executing a fetch, then git will currently allocate one reference
transaction per reference update and directly commit it. This means that
fetches are non-atomic: even if some of the reference updates fail,
others may still succeed and modify local references.

This is fine in many scenarios, but this strategy has its downsides.

- The view of remote references may be inconsistent and may show a
  bastardized state of the remote repository.

- Batching together updates may improve performance in certain
  scenarios. While the impact probably isn't as pronounced with loose
  references, the upcoming reftable backend may benefit as it needs to
  write less files in case the update is batched.

- The reference-update hook is currently being executed twice per
  updated reference. While this doesn't matter when there is no such
  hook, we have seen severe performance regressions when doing a
  git-fetch(1) with reference-transaction hook when the remote
  repository has hundreds of thousands of references.

Similar to `git push --atomic`, this commit thus introduces atomic
fetches. Instead of allocating one reference transaction per updated
reference, it causes us to only allocate a single transaction and commit
it as soon as all updates were received. If locking of any reference
fails, then we abort the complete transaction and don't update any
reference, which gives us an all-or-nothing fetch.

Note that this may not completely fix the first of above downsides, as
the consistent view also depends on the server-side. If the server
doesn't have a consistent view of its own references during the
reference negotiation phase, then the client would get the same
inconsistent view the server has. This is a separate problem though and,
if it actually exists, can be fixed at a later point.

This commit also changes the way we write FETCH_HEAD in case `--atomic`
is passed. Instead of writing changes as we go, we need to accumulate
all changes first and only commit them at the end when we know that all
reference updates succeeded. Ideally, we'd just do so via a temporary
file so that we don't need to carry all updates in-memory. This isn't
trivially doable though considering the `--append` mode, where we do not
truncate the file but simply append to it. And given that we support
concurrent processes appending to FETCH_HEAD at the same time without
any loss of data, seeding the temporary file with current contents of
FETCH_HEAD initially and then doing a rename wouldn't work either. So
this commit implements the simple strategy of buffering all changes and
appending them to the file on commit.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-12 12:06:15 -08:00
d4c8db8f1b fetch: allow passing a transaction to s_update_ref()
The handling of ref updates is completely handled by `s_update_ref()`,
which will manage the complete lifecycle of the reference transaction.
This is fine right now given that git-fetch(1) does not support atomic
fetches, so each reference gets its own transaction. It is quite
inflexible though, as `s_update_ref()` only knows about a single
reference update at a time, so it doesn't allow us to alter the
strategy.

This commit prepares `s_update_ref()` and its only caller
`update_local_ref()` to allow passing an external transaction. If none
is given, then the existing behaviour is triggered which creates a new
transaction and directly commits it. Otherwise, if the caller provides a
transaction, then we only queue the update but don't commit it. This
optionally allows the caller to manage when a transaction will be
committed.

Given that `update_local_ref()` is always called with a `NULL`
transaction for now, no change in behaviour is expected from this
change.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-12 12:06:15 -08:00
c45889f104 fetch: refactor s_update_ref to use common exit path
The cleanup code in `s_update_ref()` is currently duplicated for both
succesful and erroneous exit paths. This commit refactors the function
to have a shared exit path for both cases to remove the duplication.

Suggested-by: Christian Couder <christian.couder@gmail.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-12 12:06:15 -08:00
929d044575 fetch: use strbuf to format FETCH_HEAD updates
This commit refactors `append_fetch_head()` to use a `struct strbuf` for
formatting the update which we're about to append to the FETCH_HEAD
file. While the refactoring doesn't have much of a benefit right now, it
serves as a preparatory step to implement atomic fetches where we need
to buffer all updates to FETCH_HEAD and only flush them out if all
reference updates succeeded.

No change in behaviour is expected from this commit.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-12 12:06:14 -08:00
58a646a368 fetch: extract writing to FETCH_HEAD
When performing a fetch with the default `--write-fetch-head` option, we
write all updated references to FETCH_HEAD while the updates are
performed. Given that updates are not performed atomically, it means
that we we write to FETCH_HEAD even if some or all of the reference
updates fail.

Given that we simply update FETCH_HEAD ad-hoc with each reference, the
logic is completely contained in `store_update_refs` and thus quite hard
to extend. This can already be seen by the way we skip writing to the
FETCH_HEAD: instead of having a conditional which simply skips writing,
we instead open "/dev/null" and needlessly write all updates there.

We are about to extend git-fetch(1) to accept an `--atomic` flag which
will make the fetch an all-or-nothing operation with regards to the
reference updates. This will also require us to make the updates to
FETCH_HEAD an all-or-nothing operation, but as explained doing so is not
easy with the current layout. This commit thus refactors the wa we write
to FETCH_HEAD and pulls out the logic to open, append to, commit and
close the file. While this may seem rather over-the top at first,
pulling out this logic will make it a lot easier to update the code in a
subsequent commit. It also allows us to easily skip writing completely
in case `--no-write-fetch-head` was passed.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-12 12:06:14 -08:00
6c62f01552 for-each-repo: do nothing on empty config
'git for-each-repo --config=X' should return success without calling any
subcommands when the config key 'X' has no value. The current
implementation instead segfaults.

A user could run into this issue if they used 'git maintenance start' to
initialize their cron schedule using 'git for-each-repo
--config=maintenance.repo ...' but then using 'git maintenance
unregister' to remove the config option. (Note: 'git maintenance stop'
would remove the config _and_ remove the cron schedule.)

Add a simple test to ensure this works. Use 'git help --no-such-option'
as the potential subcommand to ensure that we will hit a failure if the
subcommand is ever run.

Reported-by: Andreas Bühmann <dev@uuml.de>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-07 19:12:02 -08:00
2708ce62d2 branch: sort detached HEAD based on a flag
Change the ref-filter sorting of detached HEAD to check the
FILTER_REFS_DETACHED_HEAD flag, instead of relying on the ref
description filled-in by get_head_description() to start with "(",
which in turn we expect to ASCII-sort before any other reference.

For context, we'd like the detached line to appear first at the start
of "git branch -l", e.g.:

    $ git branch -l
    * (HEAD detached at <hash>)
      master

This doesn't change that, but improves on a fix made in
28438e84e0 (ref-filter: sort detached HEAD lines firstly, 2019-06-18)
and gives the Chinese translation the ability to use its preferred
punctuation marks again.

In Chinese the fullwidth versions of punctuation like "()" are
typically written as (U+FF08 fullwidth left parenthesis), (U+FF09
fullwidth right parenthesis) instead[1]. This form is used in both
po/zh_{CN,TW}.po in most cases where "()" is translated in a string.

Aside from that improvement to the Chinese translation, it also just
makes for cleaner code that we mark any special cases in the ref_array
we're sorting with flags and make the sort function aware of them,
instead of piggy-backing on the general-case of strcmp() doing the
right thing.

As seen in the amended tests this made reverse sorting a bit more
consistent. Before this we'd sometimes sort this message in the
middle, now it's consistently at the beginning or end, depending on
whether we're doing a normal or reverse sort. Having it at the end
doesn't make much sense either, but at least it behaves consistently
now. A follow-up commit will make this behavior under reverse sorting
even better.

I'm removing the "TRANSLATORS" comments that were in the old code
while I'm at it. Those were added in d4919bb288 (ref-filter: move
get_head_description() from branch.c, 2017-01-10). I think it's
obvious from context, string and translation memory in typical
translation tools that these are the same or similar string.

1. https://en.wikipedia.org/wiki/Chinese_punctuation#Marks_similar_to_European_punctuation

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-07 15:13:21 -08:00
7c269a7b16 ref-filter: move ref_sorting flags to a bitfield
Change the reverse/ignore_case/version sort flags in the ref_sorting
struct into a bitfield. Having three of them was already a bit
unwieldy, but it would be even more so if another flag needed a
function like ref_sorting_icase_all() introduced in
76f9e569ad (ref-filter: apply --ignore-case to all sorting keys,
2020-05-03).

A follow-up change will introduce such a flag, so let's move this over
to a bitfield. Instead of using the usual '#define' pattern I'm using
the "enum" pattern from builtin/rebase.c's b4c8eb024a (builtin
rebase: support --quiet, 2018-09-04).

Perhaps there's a more idiomatic way of doing the "for each in list
amend mask" pattern than this "mask/on" variable combo. This function
doesn't allow us to e.g. do any arbitrary changes to the bitfield for
multiple flags, but I think in this case that's fine. The common case
is that we're calling this with a list of one.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-07 15:13:21 -08:00
8664fcb83b Merge branch 'es/worktree-repair-both-moved'
"git worktree repair" learned to deal with the case where both the
repository and the worktree moved.

* es/worktree-repair-both-moved:
  worktree: teach `repair` to fix multi-directional breakage
2021-01-06 23:33:44 -08:00
d3fa84d528 Merge branch 'fc/pull-merge-rebase'
When a user does not tell "git pull" to use rebase or merge, the
command gives a loud message telling a user to choose between
rebase or merge but creates a merge anyway, forcing users who would
want to rebase to redo the operation.  Fix an early part of this
problem by tightening the condition to give the message---there is
no reason to stop or force the user to choose between rebase or
merge if the history fast-forwards.

* fc/pull-merge-rebase:
  pull: display default warning only when non-ff
  pull: correct condition to trigger non-ff advice
  pull: get rid of unnecessary global variable
  pull: give the advice for choosing rebase/merge much later
  pull: refactor fast-forward check
2021-01-06 23:33:44 -08:00