Commit Graph

59936 Commits

Author SHA1 Message Date
brian m. carlson
9ab33150a0 perl: create and switch variables for hash constants
git-svn has several variables for SHA-1 constants, including short hash
values and full length hash values.  Since these are no longer SHA-1
specific, let's start them with "oid" instead of "sha1".  Add a
constant, oid_length, which is the length of the hash algorithm in use
in hex.  We use the hex version because overwhelmingly that's what's
used by git-svn.

We don't currently set oid_length based on the repository algorithm, but
we will in a future commit.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Acked-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 11:21:07 -07:00
brian m. carlson
148f193d16 t/lib-git-svn: make hash size independent
The record size used in the git svn storage is four bytes plus the
length of the binary hash.  Pass the hash length into our Perl
invocation and use it to compute the size of the records.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Acked-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 11:21:07 -07:00
Srinidhi Kaushik
feea6946a5 diff-files: treat "i-t-a" files as "not-in-index"
The `diff-files' command and related commands which call the function
`cmd_diff_files()', consider the "intent-to-add" files as a part of the
index when comparing the work-tree against it. This was previously
addressed in commits [1] and [2] by turning the option
`--ita-invisible-in-index' (introduced in [3]) on by default.

For `diff-files' (and `add -p' as a consequence) to show the i-t-a
files as as new, `ita_invisible_in_index' will be enabled by default
here as well.

[1] 0231ae71d3 (diff: turn --ita-invisible-in-index on by default,
                2018-05-26)
[2] 425a28e0a4 (diff-lib: allow ita entries treated as "not yet exist
                in index", 2016-10-24)
[3] b42b451919 (diff: add --ita-[in]visible-in-index, 2016-10-24)

Signed-off-by: Srinidhi Kaushik <shrinidhi.kaushik@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 10:46:45 -07:00
Eric Sunshine
03f2465bb1 worktree: drop get_worktrees() unused 'flags' argument
get_worktrees() accepts a 'flags' argument, however, there are no
existing flags (the lone flag GWT_SORT_LINKED was recently retired) and
no behavior which can be tweaked. Therefore, drop the 'flags' argument.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 10:31:15 -07:00
Eric Sunshine
d9c54c2bbf worktree: drop get_worktrees() special-purpose sorting option
Of all the clients of get_worktrees(), only "git worktree list" wants
the list sorted in a very specific way; other clients simply don't care
about the order. Rather than imbuing get_worktrees() with special
knowledge about how various clients -- now and in the future -- may want
the list sorted, drop the sorting capability altogether and make it the
client's responsibility to sort the list if needed.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 10:30:29 -07:00
brian m. carlson
3e04b6e1b6 t9101: make hash independent
Instead of hard-coding the object ID for our test .gitignore file, let's
compute it.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Acked-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 09:52:02 -07:00
brian m. carlson
bbe0616cd8 t9104: make hash size independent
The size of a record in the database used by git svn is four bytes plus
the length of the binary hash.  Instead of hard-coding 24, compute this
value based on the size of the hash in use.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Acked-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 09:52:02 -07:00
brian m. carlson
407527ba44 t9100: make test work with SHA-256
Compute the relevant tree objects for SHA-256 and use those when
appropriate instead of using the SHA-1 ones.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Acked-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 09:52:02 -07:00
brian m. carlson
606b9749c6 t9108: make test hash independent
Instead of stripping off the first 41 characters of git log output,
let's just strip off the first space-separated component, which will
work for any size hash.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Acked-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 09:52:02 -07:00
brian m. carlson
5aa6877540 t9168: make test hash independent
Instead of stripping off the first 41 characters of git log output,
let's just strip off the first space-separated component, which will
work for any size hash.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Acked-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 09:52:02 -07:00
brian m. carlson
62814dfd17 t9109: make test hash independent
Instead of stripping off the first 41 characters of git log output,
let's just strip off the first space-separated component, which will
work for any size hash.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Acked-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 09:52:02 -07:00
Elijah Newren
afda36dbf3 git-prompt: include sparsity state as well
git-prompt includes the current branch, a bunch of single character
mini-state displayers, and some much longer in-progress state
notifications.  The current branch is always shown.  The single
character mini-state displayers are all off by default (they are not
self explanatory) but each has an environment variable for turning it
on.  The in-progress state notifications provide no configuration
options for turning them off, and can be up to 15 characters long (e.g.
"|REBASE (12/18)" or "|CHERRY-PICKING").

The single character mini-state tends to be used for things like "Do you
have any stashes in refs/stash?" or "Are you ahead or behind of
upstream?".  These are things which users can take advantage of but do
not affect most normal git operations.  The in-progress states, by
contrast, suggest the user needs to interact differently and may also
prevent some normal operations from succeeding (e.g. git switch may show
an error instead of switching branches).

Sparsity is like the in-progress states in that it suggests a
fundamental different interaction with the repository (many of the files
from the repository are not present in your working copy!).  A few
commits ago added sparsity information to wt_longstatus_print_state(),
grouping it with other in-progress state displays.  We do similarly here
with the prompt and show the extra state, by default, with an extra
    |SPARSE
This state can be present simultaneously with the in-progress states, in
which case it will appear before the other states; for example,
    (branchname|SPARSE|REBASE 6/10)

The reason for showing the "|SPARSE" substring before other states is to
emphasize those other states.  Sparsity is probably not going to change
much within a repository, while temporary operations will.  So we want
the state changes related to temporary operations to be listed last, to
make them appear closer to where the user types and make them more
likely to be noticed.

The fact that sparsity isn't just cached metadata or additional
information is what leads us to show it more similarly to the
in-progress states, but the fact that sparsity is not transient like the
in-progress states might cause some users to want an abbreviated
notification of sparsity state or perhaps even be able to turn it off.
Allow GIT_PS1_COMPRESSSPARSESTATE to be set to request that it be
shortened to a single character ('?'), and GIT_PS1_OMITSPARSESTATE to be
set to request that sparsity state be omitted from the prompt entirely.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 09:29:59 -07:00
Elijah Newren
30b00f009c git-prompt: document how in-progress operations affect the prompt
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-22 09:29:59 -07:00
Pratyush Yadav
469725c1a3 Merge branch 'mt/open-worktree'
Clean up the code that checks if a directory is a Git repo. Use git
rev-parse instead of rolling our own logic to find that out. A side
effect (which also happens to be the main motivation behind it) of this
change is that git-gui can now open worktrees other than the main
worktree.

* mt/open-worktree:
  git-gui: allow opening work trees from the startup dialog
2020-06-22 20:23:28 +05:30
brian m. carlson
3716d50dd5 remote-testgit: adapt for object-format
When using an algorithm other than SHA-1, we need the remote helper to
advertise support for the object-format extension and provide
information back to us so that we can properly parse refs and return
data. Ensure that the test remote helper understands these extensions.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 14:04:09 -07:00
brian m. carlson
6161ce7bbe bundle: detect hash algorithm when reading refs
Much like with the dumb HTTP transport, there isn't a way to explicitly
specify the hash algorithm when dealing with a bundle, so detect the
algorithm based on the length of the object IDs in the prerequisites and
ref advertisements.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 14:04:09 -07:00
brian m. carlson
371c4079f4 t5300: pass --object-format to git index-pack
git index-pack by default reads the repository to determine the object
format. However, when outside of a repository, it's necessary to specify
the hash algorithm in use so that the pack can be properly indexed. Add
an --object-format argument when invoking git index-pack outside of a
repository.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 14:04:09 -07:00
brian m. carlson
4ddd3f5063 t5704: send object-format capability with SHA-256
When we speak protocol v2 in this test, we must pass the object-format
header if the algorithm is not SHA-1.  Otherwise, git upload-pack fails
because the hash algorithm doesn't match and not because we've failed to
speak the protocol correctly.  Pass the header so that our assertions
test what we're really interested in.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 14:04:09 -07:00
brian m. carlson
f7c6a3bf08 t5703: use object-format serve option
When we're using an algorithm other than SHA-1, we need to specify the
algorithm in use so we don't get a failure with an "unknown format"
message. Add a wrapper function that specifies this header if required.
Skip specifying this header for SHA-1 to test that it works both with an
without this header.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 14:04:09 -07:00
brian m. carlson
8fc7003540 t5702: offer an object-format capability in the test
In order to make this test work with SHA-256, offer an object-format
capability so that both sides use the same algorithm.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 14:04:09 -07:00
brian m. carlson
54cbbe4c6e t/helper: initialize the repository for test-sha1-array
test-sha1-array uses the_hash_algo under the hood. Since t0064 wants to
use the value that is correct for the hash algorithm that we're testing,
make sure the test helper initializes the repository to set
the_hash_algo correctly.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 14:04:08 -07:00
brian m. carlson
97997e6ad2 remote-curl: avoid truncating refs with ls-remote
Normally, the remote-curl transport helper is aware of the hash
algorithm we're using because we're in a repo with the appropriate hash
algorithm set. However, when using git ls-remote outside of a
repository, we won't have initialized the hash algorithm properly, so
use hash_to_hex_algop to print the ref corresponding to the algorithm
we've detected.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 14:04:08 -07:00
brian m. carlson
793731f742 t1050: pass algorithm to index-pack when outside repo
When outside a repository, git index-pack is unable to guess the hash
algorithm in use for a pack, since packs don't contain any information
on the algorithm in use. Pass an option to index-pack to help it out in
this test.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 14:04:08 -07:00
brian m. carlson
586740aa6e builtin/index-pack: add option to specify hash algorithm
git index-pack is usually run in a repository, but need not be. Since
packs don't contains information on the algorithm in use, instead
relying on context, add an option to index-pack to tell it which one
we're using in case someone runs it outside of a repository.  Since
using --stdin necessarily implies a repository, don't allow specifying
an object format if it's provided to prevent users from passing an
option that won't work.  Add documentation for this option.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 14:04:08 -07:00
brian m. carlson
ac093d0790 remote-curl: detect algorithm for dumb HTTP by size
When reading the info/refs file for a repository, we have no explicit
way to detect which hash algorithm is in use because the file doesn't
provide one. Detect the hash algorithm in use by the size of the first
object ID.

If we have an empty repository, we don't know what the hash algorithm is
on the remote side, so default to whatever the local side has
configured.  Without doing this, we cannot clone an empty repository
since we don't know its hash algorithm.  Test this case appropriately,
since we currently have no tests for cloning an empty repository with
the dumb HTTP protocol.

We anonymize the URL like elsewhere in the function in case the user has
decided to include a secret in the URL.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 14:04:08 -07:00
Randall S. Becker
5f2b643e76 strbuf: remove unreferenced strbuf_write_fd method.
strbuf_write_fd was only used in bugreport.c. Since that file now uses
write_in_full, this method is no longer needed. In addition, strbuf_write_fd
did not guard against exceeding MAX_IO_SIZE for the platform, nor
provided error handling in the event of a failure if only partial data
was written to the file descriptor. Since already write_in_full has this
capability and is in general use, it should be used instead. The change
impacts strbuf.c and strbuf.h.

Signed-off-by: Randall S. Becker <rsbecker@nexbridge.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 13:50:27 -07:00
Randall S. Becker
f64b6a1f75 bugreport.c: replace strbuf_write_fd with write_in_full
The strbuf_write_fd method did not provide checks for buffers larger
than MAX_IO_SIZE. Replacing with write_in_full ensures the entire
buffer will always be written to disk or report an error and die.

Signed-off-by: Randall S. Becker <rsbecker@nexbridge.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 13:50:25 -07:00
René Scharfe
0c9a4f638a pull: plug minor memory leak after using is_descendant_of()
cmd_pull() builds a commit_list to pass a single potential ancestor to
is_descendant_of().  The latter leaves the list intact.  Release the
allocated memory after the call.

Leaking in cmd_*() isn't a big deal, but sets a bad example for other
users of is_descendant_of().

Signed-off-by: René Scharfe <l.s.r@web.de>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 12:17:21 -07:00
René Scharfe
d546fe2874 commit-reach: plug minor memory leak after using is_descendant_of()
ref_newer() builds a commit_list to pass a single potential ancestor to
is_descendant_of().  The latter leaves the list intact.  Release the
allocated memory after the call.

Signed-off-by: René Scharfe <l.s.r@web.de>
Acked-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 11:06:01 -07:00
Patrick Steinhardt
6754159767 refs: implement reference transaction hook
The low-level reference transactions used to update references are
currently completely opaque to the user. While certainly desirable in
most usecases, there are some which might want to hook into the
transaction to observe all queued reference updates as well as observing
the abortion or commit of a prepared transaction.

One such usecase would be to have a set of replicas of a given Git
repository, where we perform Git operations on all of the repositories
at once and expect the outcome to be the same in all of them. While
there exist hooks already for a certain subset of Git commands that
could be used to implement a voting mechanism for this, many others
currently don't have any mechanism for this.

The above scenario is the motivation for the new "reference-transaction"
hook that reaches directly into Git's reference transaction mechanism.
The hook receives as parameter the current state the transaction was
moved to ("prepared", "committed" or "aborted") and gets via its
standard input all queued reference updates. While the exit code gets
ignored in the "committed" and "aborted" states, a non-zero exit code in
the "prepared" state will cause the transaction to be aborted
prematurely.

Given the usecase described above, a voting mechanism can now be
implemented via this hook: as soon as it gets called, it will take all
of stdin and use it to cast a vote to a central service. When all
replicas of the repository agree, the hook will exit with zero,
otherwise it will abort the transaction by returning non-zero. The most
important upside is that this will catch _all_ commands writing
references at once, allowing to implement strong consistency for
reference updates via a single mechanism.

In order to test the impact on the case where we don't have any
"reference-transaction" hook installed in the repository, this commit
introduce two new performance tests for git-update-refs(1). Run against
an empty repository, it produces the following results:

  Test                         origin/master     HEAD
  --------------------------------------------------------------------
  1400.2: update-ref           2.70(2.10+0.71)   2.71(2.10+0.73) +0.4%
  1400.3: update-ref --stdin   0.21(0.09+0.11)   0.21(0.07+0.14) +0.0%

The performance test p1400.2 creates, updates and deletes a branch a
thousand times, thus averaging runtime of git-update-refs over 3000
invocations. p1400.3 instead calls `git-update-refs --stdin` three times
and queues a thousand creations, updates and deletes respectively.

As expected, p1400.3 consistently shows no noticeable impact, as for
each batch of updates there's a single call to access(3P) for the
negative hook lookup. On the other hand, for p1400.2, one can see an
impact caused by this patchset. But doing five runs of the performance
tests where each one was run with GIT_PERF_REPEAT_COUNT=10, the overhead
ranged from -1.5% to +1.1%. These inconsistent performance numbers can
be explained by the overhead of spawning 3000 processes. This shows that
the overhead of assembling the hook path and executing access(3P) once
to check if it's there is mostly outweighed by the operating system's
overhead.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 10:46:13 -07:00
Paolo Bonzini
08dc26061f t4014: do not use "slave branch" nomenclature
Git branches have been qualified as topic branches, integration branches,
development branches, feature branches, release branches and so on.
Git has a branch that is the master *for* development, but it is not
the master *of* any "slave branch": Git does not have slave branches,
and has never had, except for a single testcase that claims otherwise. :)

Independent of any future change to the naming of the "master" branch,
removing this sole appearance of the term is a strict improvement: it
avoids divisive language, and talking about "feature branch" clarifies
which developer workflow the test is trying to emulate.

Reported-by: Till Maas <tmaas@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-19 10:26:34 -07:00
Denton Liu
a9d7689cd4 builtin/diff: update usage comment
A comment in cmd_diff() states that if one tree-ish and no blobs are
provided, (the "N=1, M=0" case), it will provide a diff between the tree
and the cache. This is incorrect because a diff happens between the
tree-ish and the working tree. Remove the `--cached` in the comment so
that the correct behavior is shown. Add a new section describing the
"N=1, M=0, --cached" behavior.

Next, describe the "N=0, M=0, --cached" case, similar to the above since
it is undocumented.

Finally, fix some spacing issues. Add spaces between each section for
consistency and readability. Also, change tabs within the comment into
spaces.

Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-18 15:01:15 -07:00
Elijah Newren
051df3cfe8 wt-status: show sparse checkout status as well
Some of the early feedback of folks trying out sparse-checkouts at
$dayjob is that sparse checkouts can sometimes be disorienting; users
can forget that they had a sparse-checkout and then wonder where files
went.  Add some output to 'git status' in the form of a simple line that
states:

    You are in a sparse checkout with 35% of files present.

where, obviously, the exact figure changes depending on what percentage
of files from the index do not have the SKIP_WORKTREE bit set.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-18 14:12:28 -07:00
Junio C Hamano
101b3204f3 The third batch
Also let's update the DEF_VER in GIT-VERSION-GEN that presuably
is not looked at by anybody ;-)

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-17 21:54:06 -07:00
Junio C Hamano
fdeb74f372 Merge branch 'es/advertise-contribution-doc'
Doc updates.

* es/advertise-contribution-doc:
  docs: mention MyFirstContribution in more places
2020-06-17 21:54:06 -07:00
Junio C Hamano
6361eb73c6 Merge branch 'dl/python-2.7-is-the-floor-version'
Document that we do not support Python 2.6 or older.

* dl/python-2.7-is-the-floor-version:
  CodingGuidelines: specify Python 2.7 is the oldest version
2020-06-17 21:54:05 -07:00
Junio C Hamano
653a3514cc Merge branch 'dl/t-readme-spell-git-correctly'
Doc updates.

* dl/t-readme-spell-git-correctly:
  t/README: avoid poor-man's small caps GIT
2020-06-17 21:54:05 -07:00
Junio C Hamano
ff9dccf615 Merge branch 'js/fuzz-commit-graph-leakfix'
Leakfix.

* js/fuzz-commit-graph-leakfix:
  fuzz-commit-graph: properly free graph struct
2020-06-17 21:54:04 -07:00
Junio C Hamano
64efa11e6b Merge branch 'en/do-match-pathspec-fix'
Use of negative pathspec, while collecting paths including
untracked ones in the working tree, was broken.

* en/do-match-pathspec-fix:
  dir: fix treatment of negated pathspecs
2020-06-17 21:54:03 -07:00
Junio C Hamano
9906d5f8e9 Merge branch 'js/msvc-build-fix'
Workaround breakage in MSVC build, where "curl-config --cflags"
gives settings appropriate for GCC build.

* js/msvc-build-fix:
  msvc: fix "REG_STARTEND" issue
2020-06-17 21:54:03 -07:00
Junio C Hamano
a554228ffb Merge branch 'en/sparse-checkout'
The behaviour of "sparse-checkout" in the state "git clone
--no-checkout" left was changed accidentally in 2.27, which has
been corrected.

* en/sparse-checkout:
  sparse-checkout: avoid staging deletions of all files
2020-06-17 21:54:02 -07:00
Junio C Hamano
524caf8035 Merge branch 'js/reflog-anonymize-for-clone-and-fetch'
The reflog entries for "git clone" and "git fetch" did not
anonymize the URL they operated on.

* js/reflog-anonymize-for-clone-and-fetch:
  clone/fetch: anonymize URLs in the reflog
2020-06-17 21:54:01 -07:00
Junio C Hamano
abacefe865 Merge branch 'tb/t5318-cleanup'
Code cleanup.

* tb/t5318-cleanup:
  t5318: test that '--stdin-commits' respects '--[no-]progress'
  t5318: use 'test_must_be_empty'
2020-06-17 21:54:01 -07:00
Junio C Hamano
0cd0afc9c6 Merge branch 'jk/diff-memuse-optim-with-stat-unmatch'
Reduce memory usage during "diff --quiet" in a worktree with too
many stat-unmatched paths.

* jk/diff-memuse-optim-with-stat-unmatch:
  diff: discard blob data from stat-unmatched pairs
2020-06-17 21:54:00 -07:00
Abhishek Kumar
c752ad09c4 commit-graph: minimize commit_graph_data_slab access
In an earlier patch, multiple struct acccesses to `graph_pos` and
`generation` were auto-converted to multiple method calls.

Since the values are fixed and commit-slab access costly, we would be
better off with storing the values as a local variable and reusing it.

Signed-off-by: Abhishek Kumar <abhishekkumar8222@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-17 14:37:52 -07:00
Abhishek Kumar
c49c82aa4c commit: move members graph_pos, generation to a slab
We remove members `graph_pos` and `generation` from the struct commit.
The default assignments in init_commit_node() are no longer valid,
which is fine as the slab helpers return appropriate default values and
the assignments are removed.

We will replace existing use of commit->generation and commit->graph_pos
by commit_graph_data_slab helpers using
`contrib/coccinelle/commit.cocci'.

Signed-off-by: Abhishek Kumar <abhishekkumar8222@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-17 14:37:30 -07:00
Abhishek Kumar
4844812b9e commit-graph: introduce commit_graph_data_slab
The struct commit is used in many contexts. However, members
`generation` and `graph_pos` are only used for commit-graph related
operations and otherwise waste memory.

This wastage would have been more pronounced as we transition to
generation number v2, which uses 64-bit generation number instead of
current 32-bits.

As they are often accessed together, let's introduce struct
commit_graph_data and move them to a commit_graph_data slab.

While the overall test suite runs just as fast as master,
(series: 26m48s, master: 27m34s, faster by 2.87%), certain commands
like `git merge-base --is-ancestor` were slowed by 40% as discovered
by Szeder Gábor [1]. After minimizing commit-slab access, the slow down
persists but is closer to 20%.

Derrick Stolee believes the slow down is attributable to the underlying
algorithm rather than the slowness of commit-slab access [2] and we will
follow-up in a later series.

[1]: https://lore.kernel.org/git/20200607195347.GA8232@szeder.dev/
[2]: https://lore.kernel.org/git/13db757a-9412-7f1e-805c-8a028c4ab2b1@gmail.com/

Signed-off-by: Abhishek Kumar <abhishekkumar8222@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-17 14:37:23 -07:00
Abhishek Kumar
6da43d937c object: drop parsed_object_pool->commit_count
14ba97f8 (alloc: allow arbitrary repositories for alloc functions,
2018-05-15) introduced parsed_object_pool->commit_count to keep count of
commits per repository and was used to assign commit->index.

However, commit-slab code requires commit->index values to be unique
and a global count would be correct, rather than a per-repo count.

Let's introduce a static counter variable, `parsed_commits_count` to
keep track of parsed commits so far.

As commit_count has no use anymore, let's also drop it from the struct.

Signed-off-by: Abhishek Kumar <abhishekkumar8222@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-17 14:37:14 -07:00
Derrick Stolee
80b8ada547 commit-reach: use fast logic in repo_in_merge_base
The repo_is_descendant_of() method is aware of the existence of the
commit-graph file. It checks for generation_numbers_enabled() before
deciding on using can_all_from_reach() or repo_in_merge_bases()
depending on the situation. The reason here is that can_all_from_reach()
uses a depth-first search that is limited by the minimum generation
number of the target commits, and that algorithm can be very slow when
generation numbers are not present. The alternative uses
paint_down_to_common() which will walk the entire merge-base boundary,
which is typically slower.

This method is used by commands like "git tag --contains" and "git
branch --contains" for very fast results when a commit-graph file
exists. Unfortunately, it is _not_ used in commands like "git merge-base
--is-ancestor" which is doing an even simpler request.

This issue was raised recently [1] with respect to a change to how
generation numbers are stored, but was also reported much earlier [2]
before commit-reach.c existed to simplify these reachability queries.

[1] https://lore.kernel.org/git/20200607195347.GA8232@szeder.dev/
[2] https://lore.kernel.org/git/87608bawoa.fsf@evledraar.gmail.com/

The root cause is that builtin/merge-base.c has a method
handle_is_ancestor() that calls in_merge_bases(), an older version of
repo_in_merge_bases(). It would be better if we have every caller to
in_merge_bases() use the logic in can_all_from_reach() when possible.

This is where things get a little tricky: repo_is_descendant_of() calls
repo_in_merge_bases() in the non-generation numbers enabled case! If we
simply update repo_in_merge_bases() to call repo_is_descendant_of()
instead of repo_in_merge_bases_many(), then we will get a recursive call
loop. Thankfully, this is caught by the test suite in the default mode
(i.e. GIT_TEST_COMMIT_GRAPH=0).

The trick, then, is to make the non-generation number case for
repo_is_descendant_of() call repo_in_merge_bases_many() directly,
skipping the non-_many version. This allows us to take advantage of this
faster code path, when possible.

The easiest way to measure the performance impact is to test the
following command on the Linux kernel repository:

	git merge-base --is-ancestor <A> <B>

  | A    | B    | Time Before | Time After |
  |------|------|-------------|------------|
  | v3.0 | v5.7 | 0.459s      | 0.028s     |
  | v4.0 | v5.7 | 0.267s      | 0.021s     |
  | v5.0 | v5.7 | 0.074s      | 0.013s     |

Note that each of these samples return success. The old code performed
the same operation when <A> and <B> are swapped. However,
can_all_from_reach() will return immediately if the generation numbers
show that <A> has larger generation number than <B>. Thus, the time for
the swapped case is universally 0.004s in each case.

Reported-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Reported-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-17 13:49:38 -07:00
Derrick Stolee
d91d6fbf26 commit-reach: create repo_is_descendant_of()
The next change will make repo_in_merge_bases() depend on the logic in
is_descendant_of(), but we need to make the method independent of
the_repository first.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-06-17 13:49:36 -07:00