Commit Graph

8331 Commits

Author SHA1 Message Date
Junio C Hamano
0460c109c3 Merge branch 'rs/name-rev-memsave'
Memory footprint and performance of "git name-rev" has been
improved.

* rs/name-rev-memsave:
  name-rev: sort tip names before applying
  name-rev: release unused name strings
  name-rev: generate name strings only if they are better
  name-rev: pre-size buffer in get_parent_name()
  name-rev: factor out get_parent_name()
  name-rev: put struct rev_name into commit slab
  name-rev: don't _peek() in create_or_update_name()
  name-rev: don't leak path copy in name_ref()
  name-rev: respect const qualifier
  name-rev: remove unused typedef
  name-rev: rewrite create_or_update_name()
2020-02-17 13:22:16 -08:00
Elijah Newren
10cdb9f38a rebase: rename the two primary rebase backends
Two related changes, with separate rationale for each:

Rename the 'interactive' backend to 'merge' because:
  * 'interactive' as a name caused confusion; this backend has been used
    for many kinds of non-interactive rebases, and will probably be used
    in the future for more non-interactive rebases than interactive ones
    given that we are making it the default.
  * 'interactive' is not the underlying strategy; merging is.
  * the directory where state is stored is not called
    .git/rebase-interactive but .git/rebase-merge.

Rename the 'am' backend to 'apply' because:
  * Few users are familiar with git-am as a reference point.
  * Related to the above, the name 'am' makes sentences in the
    documentation harder for users to read and comprehend (they may read
    it as the verb from "I am"); avoiding this difficult places a large
    burden on anyone writing documentation about this backend to be very
    careful with quoting and sentence structure and often forces
    annoying redundancy to try to avoid such problems.
  * Users stumble over pronunciation ("am" as in "I am a person not a
    backend" or "am" as in "the first and thirteenth letters in the
    alphabet in order are "A-M"); this may drive confusion when one user
    tries to explain to another what they are doing.
  * While "am" is the tool driving this backend, the tool driving git-am
    is git-apply, and since we are driving towards lower-level tools
    for the naming of the merge backend we may as well do so here too.
  * The directory where state is stored has never been called
    .git/rebase-am, it was always called .git/rebase-apply.

For all the reasons listed above:
  * Modify the documentation to refer to the backends with the new names
  * Provide a brief note in the documentation connecting the new names
    to the old names in case users run across the old names anywhere
    (e.g. in old release notes or older versions of the documentation)
  * Change the (new) --am command line flag to --apply
  * Rename some enums, variables, and functions to reinforce the new
    backend names for us as well.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00
Elijah Newren
2ac0d6273f rebase: change the default backend from "am" to "merge"
The am-backend drops information and thus limits what we can do:

  * lack of full tree information from the original commits means we
    cannot do directory rename detection and warn users that they might
    want to move some of their new files that they placed in old
    directories to prevent their becoming orphaned.[1]
  * reduction in context from only having a few lines beyond those
    changed means that when context lines are non-unique we can apply
    patches incorrectly.[2]
  * lack of access to original commits means that conflict marker
    annotation has less information available.
  * the am backend has safety problems with an ill-timed interrupt.

Also, the merge/interactive backend have far more abilities, appear to
currently have a slight performance advantage[3] and have room for more
optimizations than the am backend[4] (and work is underway to take
advantage of some of those possibilities).

[1] https://lore.kernel.org/git/xmqqh8jeh1id.fsf@gitster-ct.c.googlers.com/
[2] https://lore.kernel.org/git/CABPp-BGiu2nVMQY_t-rnFR5GQUz_ipyEE8oDocKeO+h+t4Mn4A@mail.gmail.com/
[3] https://public-inbox.org/git/CABPp-BF=ev03WgODk6TMQmuNoatg2kiEe5DR__gJ0OTVqHSnfQ@mail.gmail.com/
[4] https://lore.kernel.org/git/CABPp-BGh7yW69QwxQb13K0HM38NKmQif3A6C6UULEKYnkEJ5vA@mail.gmail.com/

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00
Elijah Newren
8295ed690b rebase: make the backend configurable via config setting
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00
Elijah Newren
c2417d3af7 rebase: drop '-i' from the reflog for interactive-based rebases
A large variety of rebase types are supported by the interactive
machinery, not just the explicitly interactive ones.  These all share
the same code and write the same reflog messages, but the "-i" moniker
in those messages doesn't really have much meaning.  It also becomes
somewhat distracting once we switch the default from the am-backend to
the interactive one.  Just remove the "-i" from these messages.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00
Elijah Newren
52eb738d6b rebase: add an --am option
Currently, this option doesn't do anything except error out if any
options requiring the interactive-backend are also passed.  However,
when we make the default backend configurable later in this series, this
flag will provide a way to override the config setting.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00
Elijah Newren
8af14f0859 rebase: move incompatibility checks between backend options a bit earlier
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00
Elijah Newren
befb89ce7c rebase: allow more types of rebases to fast-forward
In the past, we dis-allowed rebases using the interactive backend from
performing a fast-forward to short-circuit the rebase operation.  This
made sense for explicitly interactive rebases and some implicitly
interactive rebases, but certainly became overly stringent when the
merge backend was re-implemented via the interactive backend.

Just as the am-based rebase has always had to disable the fast-forward
based on a variety of conditions or flags (e.g. --signoff, --whitespace,
etc.), we need to do the same but now with a few more options.  However,
continuing to use REBASE_FORCE for tracking this is problematic because
the interactive backend used it for a different purpose.  (When
REBASE_FORCE wasn't set, the interactive backend would not fast-forward
the whole series but would fast-forward individual "pick" commits at the
beginning of the todo list, and then a squash or something would cause
it to start generating new commits.)  So, introduce a new
allow_preemptive_ff flag contained within cmd_rebase() and use it to
track whether we are going to allow a pre-emptive fast-forward that
short-circuits the whole rebase.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00
Elijah Newren
93122c985a rebase: fix handling of restrict_revision
restrict_revision in the original shell script was an excluded revision
range.  It is also treated that way by the am-backend.  In the
conversion from shell to C (see commit 6ab54d17be ("rebase -i:
implement the logic to initialize $revisions in C", 2018-08-28)), the
interactive-backend accidentally treated it as a positive revision
rather than a negated one.

This was missed as there were no tests in the testsuite that tested an
interactive rebase with fork-point behavior.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00
Elijah Newren
55d2b6d785 rebase: make sure to pass along the quiet flag to the sequencer
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00
Elijah Newren
8a997ed132 rebase, sequencer: remove the broken GIT_QUIET handling
The GIT_QUIET environment variable was used to signal the non-am
backends that the rebase should perform quietly.  The preserve-merges
backend does not make use of the quiet flag anywhere (other than to
write out its state whenever it writes state), and this mechanism was
broken in the conversion from shell to C.  Since this environment
variable was specifically designed for scripts and the only backend that
would still use it is no longer a script, just gut this code.

A subsequent commit will fix --quiet for the interactive/merge backend
in a different way.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00
Elijah Newren
e98c4269c8 rebase (interactive-backend): fix handling of commits that become empty
As established in the previous commit and commit b00bf1c9a8
(git-rebase: make --allow-empty-message the default, 2018-06-27), the
behavior for rebase with different backends in various edge or corner
cases is often more happenstance than design.  This commit addresses
another such corner case: commits which "become empty".

A careful reader may note that there are two types of commits which would
become empty due to a rebase:

  * [clean cherry-pick] Commits which are clean cherry-picks of upstream
    commits, as determined by `git log --cherry-mark ...`.  Re-applying
    these commits would result in an empty set of changes and a
    duplicative commit message; i.e. these are commits that have
    "already been applied" upstream.

  * [become empty] Commits which are not empty to start, are not clean
    cherry-picks of upstream commits, but which still become empty after
    being rebased.  This happens e.g. when a commit has changes which
    are a strict subset of the changes in an upstream commit, or when
    the changes of a commit can be found spread across or among several
    upstream commits.

Clearly, in both cases the changes in the commit in question are found
upstream already, but the commit message may not be in the latter case.

When cherry-mark can determine a commit is already upstream, then
because of how cherry-mark works this means the upstream commit message
was about the *exact* same set of changes.  Thus, the commit messages
can be assumed to be fully interchangeable (and are in fact likely to be
completely identical).  As such, the clean cherry-pick case represents a
case when there is no information to be gained by keeping the extra
commit around.  All rebase types have always dropped these commits, and
no one to my knowledge has ever requested that we do otherwise.

For many of the become empty cases (and likely even most), we will also
be able to drop the commit without loss of information -- but this isn't
quite always the case.  Since these commits represent cases that were
not clean cherry-picks, there is no upstream commit message explaining
the same set of changes.  Projects with good commit message hygiene will
likely have the explanation from our commit message contained within or
spread among the relevant upstream commits, but not all projects run
that way.  As such, the commit message of the commit being rebased may
have reasoning that suggests additional changes that should be made to
adapt to the new base, or it may have information that someone wants to
add as a note to another commit, or perhaps someone even wants to create
an empty commit with the commit message as-is.

Junio commented on the "become-empty" types of commits as follows[1]:

    WRT a change that ends up being empty (as opposed to a change that
    is empty from the beginning), I'd think that the current behaviour
    is desireable one.  "am" based rebase is solely to transplant an
    existing history and want to stop much less than "interactive" one
    whose purpose is to polish a series before making it publishable,
    and asking for confirmation ("this has become empty--do you want to
    drop it?") is more appropriate from the workflow point of view.

[1] https://lore.kernel.org/git/xmqqfu1fswdh.fsf@gitster-ct.c.googlers.com/

I would simply add that his arguments for "am"-based rebases actually
apply to all non-explicitly-interactive rebases.  Also, since we are
stating that different cases should have different defaults, it may be
worth providing a flag to allow users to select which behavior they want
for these commits.

Introduce a new command line flag for selecting the desired behavior:
    --empty={drop,keep,ask}
with the definitions:
    drop: drop commits which become empty
    keep: keep commits which become empty
    ask:  provide the user a chance to interact and pick what to do with
          commits which become empty on a case-by-case basis

In line with Junio's suggestion, if the --empty flag is not specified,
pick defaults as follows:
    explicitly interactive: ask
    otherwise: drop

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00
Elijah Newren
d48e5e21da rebase (interactive-backend): make --keep-empty the default
Different rebase backends have different treatment for commits which
start empty (i.e. have no changes relative to their parent), and the
--keep-empty option was added at some point to allow adjusting behavior.
The handling of commits which start empty is actually quite similar to
commit b00bf1c9a8 (git-rebase: make --allow-empty-message the default,
2018-06-27), which pointed out that the behavior for various backends is
often more happenstance than design.  The specific change made in that
commit is actually quite relevant as well and much of the logic there
directly applies here.

It makes a lot of sense in 'git commit' to error out on the creation of
empty commits, unless an override flag is provided.  However, once
someone determines that there is a rare case that merits using the
manual override to create such a commit, it is somewhere between
annoying and harmful to have to take extra steps to keep such
intentional commits around.  Granted, empty commits are quite rare,
which is why handling of them doesn't get considered much and folks tend
to defer to existing (accidental) behavior and assume there was a reason
for it, leading them to just add flags (--keep-empty in this case) that
allow them to override the bad defaults.  Fix the interactive backend so
that --keep-empty is the default, much like we did with
--allow-empty-message.  The am backend should also be fixed to have
--keep-empty semantics for commits that start empty, but that is not
included in this patch other than a testcase documenting the failure.

Note that there was one test in t3421 which appears to have been written
expecting --keep-empty to not be the default as correct behavior.  This
test was introduced in commit 00b8be5a4d ("add tests for rebasing of
empty commits", 2013-06-06), which was part of a series focusing on
rebase topology and which had an interesting original cover letter at
https://lore.kernel.org/git/1347949878-12578-1-git-send-email-martinvonz@gmail.com/
which noted
    Your input especially appreciated on whether you agree with the
    intent of the test cases.
and then went into a long example about how one of the many tests added
had several questions about whether it was correct.  As such, I believe
most the tests in that series were about testing rebase topology with as
many different flags as possible and were not trying to state in general
how those flags should behave otherwise.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-16 15:40:42 -08:00
Junio C Hamano
53c3be2c29 Merge branch 'tb/commit-graph-object-dir'
The code to compute the commit-graph has been taught to use a more
robust way to tell if two object directories refer to the same
thing.

* tb/commit-graph-object-dir:
  commit-graph.h: use odb in 'load_commit_graph_one_fd_st'
  commit-graph.c: remove path normalization, comparison
  commit-graph.h: store object directory in 'struct commit_graph'
  commit-graph.h: store an odb in 'struct write_commit_graph_context'
  t5318: don't pass non-object directory to '--object-dir'
2020-02-14 12:54:24 -08:00
Junio C Hamano
7b029ebaef Merge branch 'jk/index-pack-dupfix'
The index-pack code now diagnoses a bad input packstream that
records the same object twice when it is used as delta base; the
code used to declare a software bug when encountering such an
input, but it is an input error.

* jk/index-pack-dupfix:
  index-pack: downgrade twice-resolved REF_DELTA to die()
2020-02-14 12:54:24 -08:00
Junio C Hamano
f2dcfcc21d Merge branch 'pk/status-of-uncloned-submodule'
The way "git submodule status" reports an initialized but not yet
populated submodule has not been reimplemented correctly when a
part of the "git submodule" command was rewritten in C, which has
been corrected.

* pk/status-of-uncloned-submodule:
  t7400: testcase for submodule status on unregistered inner git repos
  submodule: fix status of initialized but not cloned submodules
  t7400: add a testcase for submodule status on empty dirs
2020-02-14 12:54:23 -08:00
Junio C Hamano
78e67cda42 Merge branch 'mt/use-passed-repo-more-in-funcs'
Some codepaths were given a repository instance as a parameter to
work in the repository, but passed the_repository instance to its
callees, which has been cleaned up (somewhat).

* mt/use-passed-repo-more-in-funcs:
  sha1-file: allow check_object_signature() to handle any repo
  sha1-file: pass git_hash_algo to hash_object_file()
  sha1-file: pass git_hash_algo to write_object_file_prepare()
  streaming: allow open_istream() to handle any repo
  pack-check: use given repo's hash_algo at verify_packfile()
  cache-tree: use given repo's hash_algo at verify_one()
  diff: make diff_populate_filespec() honor its repo argument
2020-02-14 12:54:22 -08:00
Junio C Hamano
433b8aac2e Merge branch 'ds/sparse-checkout-harden'
Some rough edges in the sparse-checkout feature, especially around
the cone mode, have been cleaned up.

* ds/sparse-checkout-harden:
  sparse-checkout: fix cone mode behavior mismatch
  sparse-checkout: improve docs around 'set' in cone mode
  sparse-checkout: escape all glob characters on write
  sparse-checkout: use C-style quotes in 'list' subcommand
  sparse-checkout: unquote C-style strings over --stdin
  sparse-checkout: write escaped patterns in cone mode
  sparse-checkout: properly match escaped characters
  sparse-checkout: warn on globs in cone patterns
  sparse-checkout: detect short patterns
  sparse-checkout: cone mode does not recognize "**"
  sparse-checkout: fix documentation typo for core.sparseCheckoutCone
  clone: fix --sparse option with URLs
  sparse-checkout: create leading directories
  t1091: improve here-docs
  t1091: use check_files to reduce boilerplate
2020-02-14 12:54:22 -08:00
Junio C Hamano
8fb3945037 Merge branch 'jt/connectivity-check-optim-in-partial-clone'
Unneeded connectivity check is now disabled in a partial clone when
fetching into it.

* jt/connectivity-check-optim-in-partial-clone:
  fetch: forgo full connectivity check if --filter
  connected: verify promisor-ness of partial clone
2020-02-14 12:54:21 -08:00
Junio C Hamano
d8b8d59054 Merge branch 'ag/rebase-avoid-unneeded-checkout'
"git rebase -i" (and friends) used to unnecessarily check out the
tip of the branch to be rebased, which has been corrected.

* ag/rebase-avoid-unneeded-checkout:
  rebase -i: stop checking out the tip of the branch to rebase
2020-02-14 12:54:21 -08:00
Junio C Hamano
56ceb64eb0 Merge branch 'mt/threaded-grep-in-object-store'
Traditionally, we avoided threaded grep while searching in objects
(as opposed to files in the working tree) as accesses to the object
layer is not thread-safe.  This limitation is getting lifted.

* mt/threaded-grep-in-object-store:
  grep: use no. of cores as the default no. of threads
  grep: move driver pre-load out of critical section
  grep: re-enable threads in non-worktree case
  grep: protect packed_git [re-]initialization
  grep: allow submodule functions to run in parallel
  submodule-config: add skip_if_read option to repo_read_gitmodules()
  grep: replace grep_read_mutex by internal obj read lock
  object-store: allow threaded access to object reading
  replace-object: make replace operations thread-safe
  grep: fix racy calls in grep_objects()
  grep: fix race conditions at grep_submodule()
  grep: fix race conditions on userdiff calls
2020-02-14 12:54:20 -08:00
Junio C Hamano
a14aebeac3 Merge branch 'jk/packfile-reuse-cleanup'
The way "git pack-objects" reuses objects stored in existing pack
to generate its result has been improved.

* jk/packfile-reuse-cleanup:
  pack-bitmap: don't rely on bitmap_git->reuse_objects
  pack-objects: add checks for duplicate objects
  pack-objects: improve partial packfile reuse
  builtin/pack-objects: introduce obj_is_packed()
  pack-objects: introduce pack.allowPackReuse
  csum-file: introduce hashfile_total()
  pack-bitmap: simplify bitmap_has_oid_in_uninteresting()
  pack-bitmap: uninteresting oid can be outside bitmapped packfile
  pack-bitmap: introduce bitmap_walk_contains()
  ewah/bitmap: introduce bitmap_word_alloc()
  packfile: expose get_delta_base()
  builtin/pack-objects: report reused packfile objects
2020-02-14 12:54:19 -08:00
Junio C Hamano
daef1b300b Merge branch 'hw/advice-add-nothing'
Two help messages given when "git add" notices the user gave it
nothing to add have been updated to use advise() API.

* hw/advice-add-nothing:
  add: change advice config variables used by the add API
  add: use advise function to display hints
2020-02-14 12:54:19 -08:00
Junio C Hamano
153a1b46f1 Merge branch 'pb/do-not-recurse-grep-no-index' into maint
"git grep --no-index" should not get affected by the contents of
the .gitmodules file but when "--recurse-submodules" is given or
the "submodule.recurse" variable is set, it did.  Now these
settings are ignored in the "--no-index" mode.

* pb/do-not-recurse-grep-no-index:
  grep: ignore --recurse-submodules if --no-index is given
2020-02-14 12:42:31 -08:00
Junio C Hamano
e361f36f61 Merge branch 'nd/switch-and-restore' into maint
"git restore --staged" did not correctly update the cache-tree
structure, resulting in bogus trees to be written afterwards, which
has been corrected.

* nd/switch-and-restore:
  restore: invalidate cache-tree when removing entries with --staged
2020-02-14 12:42:29 -08:00
Junio C Hamano
3bba763373 Merge branch 'hw/commit-advise-while-rejecting' into maint
"git commit" gives output similar to "git status" when there is
nothing to commit, but without honoring the advise.statusHints
configuration variable, which has been corrected.

* hw/commit-advise-while-rejecting:
  commit: honor advice.statusHints when rejecting an empty commit
2020-02-14 12:42:27 -08:00
Jeff King
3ab3185f99 pack-objects: support filters with bitmaps
Just as rev-list recently learned to combine filters and bitmaps, let's
do the same for pack-objects. The infrastructure is all there; we just
need to pass along our filter options, and the pack-bitmap code will
decide to use bitmaps or not.

This unsurprisingly makes things faster for partial clones of large
repositories (here we're cloning linux.git):

  Test                               HEAD^               HEAD
  ------------------------------------------------------------------------------
  5310.11: simulated partial clone   38.94(37.28+5.87)   11.06(11.27+4.07) -71.6%

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-14 10:46:22 -08:00
Jeff King
2aaeb9ac41 rev-list: use bitmap filters for traversal
This just passes the filter-options struct to prepare_bitmap_walk().
Since the bitmap code doesn't actually support any filters yet, it will
fallback to the non-bitmap code if any --filter is specified. But this
lets us exercise that rejection code path, as well as getting us ready
to test filters via rev-list when we _do_ support them.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-14 10:46:22 -08:00
Jeff King
6663ae0a08 pack-bitmap: basic noop bitmap filter infrastructure
Currently you can't use object filters with bitmaps, but we plan to
support at least some filters with bitmaps. Let's introduce some
infrastructure that will help us do that:

  - prepare_bitmap_walk() now accepts a list_objects_filter_options
    parameter (which can be NULL for no filtering; all the current
    callers pass this)

  - we'll bail early if the filter is incompatible with bitmaps (just as
    we would if there were no bitmaps at all). Currently all filters are
    incompatible.

  - we'll filter the resulting bitmap; since there are no supported
    filters yet, this is always a noop.

There should be no behavior change yet, but we'll support some actual
filters in a future patch.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-14 10:46:22 -08:00
Jeff King
4eb707ebd6 rev-list: allow commit-only bitmap traversals
Ever since we added reachability bitmap support, we've been able to use
it with rev-list to get the full list of objects, like:

  git rev-list --objects --use-bitmap-index --all

But you can't do so without --objects, since we weren't ready to just
show the commits. However, the internals of the bitmap code are mostly
ready for this: they avoid opening up trees when walking to fill in the
bitmaps. We just need to actually pass in the rev_info to
traverse_bitmap_commit_list() so it knows which types to bother
triggering our callback for.

For completeness, the perf test now covers both the existing --objects
case, as well as the new commits-only behavior (the objects one got way
faster when we introduced bitmaps, but obviously isn't improved now).

Here are numbers for linux.git:

  Test                         HEAD^               HEAD
  ------------------------------------------------------------------------
  5310.7: rev-list (commits)   8.29(8.10+0.19)       1.76(1.72+0.04) -78.8%
  5310.8: rev-list (objects)   8.06(7.94+0.12)       8.14(7.94+0.13) +1.0%

That run was cheating a little, as I didn't have any commit-graph in the
repository, and we'd built it by default these days when running git-gc.
Here are numbers with a commit-graph:

  Test                         HEAD^               HEAD
  ------------------------------------------------------------------------
  5310.7: rev-list (commits)   0.70(0.58+0.12)     0.51(0.46+0.04) -27.1%
  5310.8: rev-list (objects)   6.20(6.09+0.10)     6.27(6.16+0.11) +1.1%

Still an improvement, but a lot less impressive.

We could have the perf script remove any commit-graph to show the
out-sized effect, but it probably makes sense to leave it in what would
be a more typical setup.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-14 10:46:22 -08:00
Jeff King
608d9c9365 rev-list: allow bitmaps when counting objects
The prior commit taught "--count --objects" to work without bitmaps. We
should be able to get the same answer much more quickly with bitmaps.

Note that we punt on the max_count case here. This perhaps _could_ be
made to work if we find all of the boundary commits and treat them as
UNINTERESTING, subtracting them (and their reachable objects) from the
set we return. That implies an actual commit traversal, but we'd still
be faster due to avoiding opening up any trees. Given the complexity and
the fact that anyone is unlikely to want this, it makes sense to just
fall back to the non-bitmap case for now.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-14 10:46:22 -08:00
Jeff King
55cb10f9b5 rev-list: make --count work with --objects
The current behavior from "rev-list --count --objects" is nonsensical:
we enumerate all of the objects except commits, but then give a count of
commits. This wasn't planned, and is just what the code happens to do.

Instead, let's give the answer the user almost certainly wanted: the
full count of objects.

Note that there are more complicated cases around cherry-marking, etc.
We'll punt on those for now, but let the user know that we can't produce
an answer (rather than giving them something useless).

We'll test both the new feature as well as a vanilla --count of commits,
since that surprisingly doesn't seem to be covered in the existing
tests.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-14 10:46:22 -08:00
Jeff King
792f811998 rev-list: factor out bitmap-optimized routines
There are a few operations in rev-list that are optimized for bitmaps.
Rather than having the code inline in cmd_rev_list(), let's move them
into helpers. This not only makes the flow of the main function simpler,
but it lets us replace the complex "can we do the optimization?"
conditionals with a series of early returns from the functions. That
also makes it easy to add comments explaining those conditions.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-14 10:46:22 -08:00
Jeff King
d90fe06ea7 pack-bitmap: refuse to do a bitmap traversal with pathspecs
rev-list has refused to use bitmaps with pathspec limiting since
c8a70d3509 (rev-list: disable --use-bitmap-index when pruning commits,
2015-07-01). But this is true not just for rev-list, but for anyone who
calls prepare_bitmap_walk(); the code isn't equipped to handle this
case.  We never noticed because the only other callers would never pass
a pathspec limiter.

But let's push the check down into prepare_bitmap_walk() anyway. That's
a more logical place for it to live, as callers shouldn't need to know
the details (and must be prepared to fall back to a regular traversal
anyway, since there might not be bitmaps in the repository).

It would also prepare us for a day where this case _is_ handled, but
that's pretty unlikely. E.g., we could use bitmaps to generate the set
of commits, and then diff each commit to see if it matches the pathspec.
That would be slightly faster than a naive traversal that actually walks
the commits. But you'd probably do better still to make use of the newer
commit-graph feature to make walking the commits very cheap.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-14 10:46:22 -08:00
Jeff King
e03f928e2a rev-list: fallback to non-bitmap traversal when filtering
The "--use-bitmap-index" option is usually aspirational: if we have
bitmaps and the request can be fulfilled more quickly using them we'll
do so, but otherwise fall back to a non-bitmap traversal.

The exception is object filtering, which explicitly dies if the two
options are combined. Let's convert this to the usual fallback behavior.
This is a minor convenience for now (since the caller can easily know
that --filter and --use-bitmap-index don't combine), but will become
much more useful as we start to support _some_ filters with bitmaps, but
not others.

The test infrastructure here is bigger than necessary for checking this
one small feature. But it will serve as the basis for more filtering
bitmap tests in future patches.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-13 09:08:58 -08:00
Junio C Hamano
44cba9c4b3 Merge branch 'jc/skip-prefix'
Code simplification.

* jc/skip-prefix:
  C: use skip_prefix() to avoid hardcoded string length
2020-02-12 12:41:37 -08:00
Junio C Hamano
556ccd4dd2 Merge branch 'pb/do-not-recurse-grep-no-index'
"git grep --no-index" should not get affected by the contents of
the .gitmodules file but when "--recurse-submodules" is given or
the "submodule.recurse" variable is set, it did.  Now these
settings are ignored in the "--no-index" mode.

* pb/do-not-recurse-grep-no-index:
  grep: ignore --recurse-submodules if --no-index is given
2020-02-12 12:41:36 -08:00
Derrick Stolee
ef07659926 sparse-checkout: work with Windows paths
When using Windows, a user may run 'git sparse-checkout set A\B\C'
to add the Unix-style path A/B/C to their sparse-checkout patterns.
Normalizing the input path converts the backslashes to slashes before we
add the string 'A/B/C' to the recursive hashset.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-11 09:06:47 -08:00
Derrick Stolee
2631dc879d sparse-checkout: create 'add' subcommand
When using the sparse-checkout feature, a user may want to incrementally
grow their sparse-checkout pattern set. Allow adding patterns using a
new 'add' subcommand. This is not much different from the 'set'
subcommand, because we still want to allow the '--stdin' option and
interpret inputs as directories when in cone mode and patterns
otherwise.

When in cone mode, we are growing the cone. This may actually reduce the
set of patterns when adding directory A when A/B is already a directory
in the cone. Test the different cases: siblings, parents, ancestors.

When not in cone mode, we can only assume the patterns should be
appended to the sparse-checkout file.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-11 09:06:46 -08:00
Derrick Stolee
4bf0c06c71 sparse-checkout: extract pattern update from 'set' subcommand
In anticipation of adding "add" and "remove" subcommands to the
sparse-checkout builtin, extract a modify_pattern_list() method from the
sparse_checkout_set() method. This command will read input from the
command-line or stdin to construct a set of patterns, then modify the
existing sparse-checkout patterns after a successful update of the
working directory.

Currently, the only way to modify the patterns is to replace all of the
patterns. This will be extended in a later update.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-11 08:47:13 -08:00
Derrick Stolee
6fb705abcb sparse-checkout: extract add_patterns_from_input()
In anticipation of extending the sparse-checkout builtin with "add"
and "remove" subcommands, extract the code that fills a pattern list
based on the input values. The input changes depending on the
presence of "--stdin" or the value of core.sparseCheckoutCone.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-11 08:47:11 -08:00
Bert Wesarg
b3fd6cbf29 remote rename/remove: gently handle remote.pushDefault config
When renaming a remote with

    git remote rename X Y
    git remote remove X

Git already renames or removes any branch.<name>.remote and
branch.<name>.pushRemote configurations if their value is X.

However remote.pushDefault needs a more gentle approach, as this may be
set in a non-repo configuration file. In such a case only a warning is
printed, such as:

warning: The global configuration remote.pushDefault in:
	$HOME/.gitconfig:35
now names the non-existent remote origin

It is changed to remote.pushDefault = Y or removed when set in a repo
configuration though.

Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-10 10:52:10 -08:00
Bert Wesarg
923d4a5ca4 remote rename/remove: handle branch.<name>.pushRemote config values
When renaming or removing a remote with

    git remote rename X Y
    git remote remove X

Git already renames/removes any config values from

    branch.<name>.remote = X

to

    branch.<name>.remote = Y

As branch.<name>.pushRemote also names a remote, it now also renames
or removes these config values from

    branch.<name>.pushRemote = X

to

    branch.<name>.pushRemote = Y

Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-10 10:52:10 -08:00
Bert Wesarg
ceff1a1308 remote: clean-up config callback
Some minor clean-ups in function `config_read_branches`:

 * remove hardcoded length in `key += 7`
 * call `xmemdupz` only once
 * use a switch to handle the configuration type and add a `BUG()`

Suggested-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-10 10:52:10 -08:00
Bert Wesarg
1a83068c26 remote: clean-up by returning early to avoid one indentation
Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-10 10:52:10 -08:00
Bert Wesarg
88f8576eda pull --rebase/remote rename: document and honor single-letter abbreviations rebase types
When 46af44b07d (pull --rebase=<type>: allow single-letter abbreviations
for the type, 2018-08-04) landed in Git, it had the side effect that
not only 'pull --rebase=<type>' accepted the single-letter abbreviations
but also the 'pull.rebase' and 'branch.<name>.rebase' configurations.

However, 'git remote rename' did not honor these single-letter
abbreviations when reading the 'branch.*.rebase' configurations.

We now document the single-letter abbreviations and both code places
share a common function to parse the values of 'git pull --rebase=*',
'pull.rebase', and 'branches.*.rebase'.

The only functional change is the handling of the `branch_info::rebase`
value. Before it was an unsigned enum, thus the truth value could be
checked with `branch_info::rebase != 0`. But `enum rebase_type` is
signed, thus the truth value must now be checked with
`branch_info::rebase >= REBASE_TRUE`

Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-10 10:52:10 -08:00
Matthew Rogers
145d59f482 config: add '--show-scope' to print the scope of a config value
When a user queries config values with --show-origin, often it's
difficult to determine what the actual "scope" (local, global, etc.) of
a given value is based on just the origin file.

Teach 'git config' the '--show-scope' option to print the scope of all
displayed config values.  Note that we should never see anything of
"submodule" scope as that is only ever used by submodule-config.c when
parsing the '.gitmodules' file.

Signed-off-by: Matthew Rogers <mattr94@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-10 10:49:12 -08:00
Matthew Rogers
e37efa40e1 config: teach git_config_source to remember its scope
There are many situations where the scope of a config command is known
beforehand, such as passing of '--local', '--file', etc. to an
invocation of git config.  However, this information is lost when moving
from builtin/config.c to /config.c.  This historically hasn't been a big
deal, but to prepare for the upcoming --show-scope option we teach
git_config_source to keep track of the source and the config machinery
to use that information to set current_parsing_scope appropriately.

Signed-off-by: Matthew Rogers <mattr94@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-10 10:49:10 -08:00
René Scharfe
a91cc7fad0 strbuf: add and use strbuf_insertstr()
Add a function for inserting a C string into a strbuf.  Use it
throughout the source to get rid of magic string length constants and
explicit strlen() calls.

Like strbuf_addstr(), implement it as an inline function to avoid the
implicit strlen() calls to cause runtime overhead.

Helped-by: Taylor Blau <me@ttaylorr.com>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-10 09:04:45 -08:00
Heba Waly
887a0fd573 add: change advice config variables used by the add API
advice.addNothing config variable is used to control the visibility of
two advice messages in the add library. This config variable is
replaced by two new variables, whose names are more clear and relevant
to the two cases.

Also add the two new variables to the documentation.

Signed-off-by: Heba Waly <heba.waly@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-06 11:08:00 -08:00
Junio C Hamano
d0e70cd32e Merge branch 'am/checkout-file-and-ref-ref-ambiguity'
"git checkout X" did not correctly fail when X is not a local
branch but could name more than one remote-tracking branches
(i.e. to be dwimmed as the starting point to create a corresponding
local branch), which has been corrected.

* am/checkout-file-and-ref-ref-ambiguity:
  checkout: don't revert file on ambiguous tracking branches
  parse_branchname_arg(): extract part as new function
2020-02-05 14:34:58 -08:00
Junio C Hamano
9a5315edfd Merge branch 'js/patch-mode-in-others-in-c'
The effort to move "git-add--interactive" to C continues.

* js/patch-mode-in-others-in-c:
  commit --interactive: make it work with the built-in `add -i`
  built-in add -p: implement the "worktree" patch modes
  built-in add -p: implement the "checkout" patch modes
  built-in stash: use the built-in `git add -p` if so configured
  legacy stash -p: respect the add.interactive.usebuiltin setting
  built-in add -p: implement the "stash" and "reset" patch modes
  built-in add -p: prepare for patch modes other than "stage"
2020-02-05 14:34:58 -08:00
René Scharfe
079f970971 name-rev: sort tip names before applying
name_ref() is called for each ref and checks if its a better name for
the referenced commit.  If that's the case it remembers it and checks if
a name based on it is better for its ancestors as well.  This in done in
the the order for_each_ref() imposes on us.

That might not be optimal.  If bad names happen to be encountered first
(as defined by is_better_name()), names derived from them may spread to
a lot of commits, only to be replaced by better names later.  Setting
better names first can avoid that.

is_better_name() prefers tags, short distances and old references.  The
distance is a measure that we need to calculate for each candidate
commit, but the other two properties are not dependent on the
relationships of commits.  Sorting the refs by them should yield better
performance than the essentially random order we currently use.

And applying older references first should also help to reduce rework
due to the fact that older commits have less ancestors than newer ones.

So add all details of names to the tip table first, then sort them
to prefer tags and older references and then apply them in this order.
Here's the performance as measures by hyperfine for the Linux repo
before:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     851.1 ms ±   4.5 ms    [User: 806.7 ms, System: 44.4 ms]
  Range (min … max):   845.9 ms … 859.5 ms    10 runs

... and with this patch:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     736.2 ms ±   8.7 ms    [User: 688.4 ms, System: 47.5 ms]
  Range (min … max):   726.0 ms … 755.2 ms    10 runs

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:36:33 -08:00
René Scharfe
2d53975488 name-rev: release unused name strings
name_rev() assigns a name to a commit and its parents and grandparents
and so on.  Commits share their name string with their first parent,
which in turn does the same, recursively to the root.  That saves a lot
of allocations.  When a better name is found, the old name is replaced,
but its memory is not released.  That leakage can become significant.

Can we release these old strings exactly once even though they are
referenced multiple times?  Yes, indeed -- we can make use of the fact
that name_rev() visits the ancestors of a commit after it set a new name
for it and tries to update their names as well.

Members of the first ancestral line have the same taggerdate and
from_tag values, but a higher distance value than their child commit at
generation 0.  These are the only criteria used by is_better_name().
Lower distance values are considered better, so a name that is better
for a child will also be better for its parent and grandparent etc.

That means we can free(3) an inferior name at generation 0 and rely on
name_rev() to replace all references in ancestors as well.

If we do that then we need to stop using the string pointer alone to
distinguish new empty rev_name slots from initialized ones, though, as
it technically becomes invalid after the free(3) call -- even though its
value is still different from NULL.

We can check the generation value first, as empty slots will have it
initialized to 0, and for the actual generation 0 we'll set a new valid
name right after the create_or_update_name() call that releases the
string.

For the Chromium repo, releasing superceded names reduces the memory
footprint of name-rev --all significantly.  Here's the output of GNU
time before:

0.98user 0.48system 0:01.46elapsed 99%CPU (0avgtext+0avgdata 2601812maxresident)k
0inputs+0outputs (0major+571470minor)pagefaults 0swaps

... and with this patch:

1.01user 0.26system 0:01.28elapsed 100%CPU (0avgtext+0avgdata 1559196maxresident)k
0inputs+0outputs (0major+314370minor)pagefaults 0swaps

It also gets faster; hyperfine before:

Benchmark #1: ./git -C ../chromium/src name-rev --all
  Time (mean ± σ):      1.534 s ±  0.006 s    [User: 1.039 s, System: 0.494 s]
  Range (min … max):    1.522 s …  1.542 s    10 runs

... and with this patch:

Benchmark #1: ./git -C ../chromium/src name-rev --all
  Time (mean ± σ):      1.338 s ±  0.006 s    [User: 1.047 s, System: 0.291 s]
  Range (min … max):    1.327 s …  1.346 s    10 runs

For the Linux repo it doesn't pay off; memory usage only gets down from:

0.76user 0.03system 0:00.80elapsed 99%CPU (0avgtext+0avgdata 292848maxresident)k
0inputs+0outputs (0major+44579minor)pagefaults 0swaps

... to:

0.78user 0.03system 0:00.81elapsed 100%CPU (0avgtext+0avgdata 284696maxresident)k
0inputs+0outputs (0major+44892minor)pagefaults 0swaps

The runtime actually increases slightly from:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     828.8 ms ±   5.0 ms    [User: 797.2 ms, System: 31.6 ms]
  Range (min … max):   824.1 ms … 838.9 ms    10 runs

... to:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     847.6 ms ±   3.4 ms    [User: 807.9 ms, System: 39.6 ms]
  Range (min … max):   843.4 ms … 854.3 ms    10 runs

Why is that?  In the Chromium repo, ca. 44000 free(3) calls in
create_or_update_name() release almost 1GB, while in the Linux repo
240000+ calls release a bit more than 5MB, so the average discarded
name is ca.  1000x longer in the latter.

Overall I think it's the right tradeoff to make, as it helps curb the
memory usage in repositories with big discarded names, and the added
overhead is small.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
977dc1912b name-rev: generate name strings only if they are better
Leave setting the tip_name member of struct rev_name to callers of
create_or_update_name().  This avoids allocations for names that are
rejected by that function.  Here's how this affects the runtime when
working with a fresh clone of Git's own repository; performance numbers
by hyperfine before:

Benchmark #1: ./git -C ../git-pristine/ name-rev --all
  Time (mean ± σ):     437.8 ms ±   4.0 ms    [User: 422.5 ms, System: 15.2 ms]
  Range (min … max):   432.8 ms … 446.3 ms    10 runs

... and with this patch:

Benchmark #1: ./git -C ../git-pristine/ name-rev --all
  Time (mean ± σ):     408.5 ms ±   1.4 ms    [User: 387.2 ms, System: 21.2 ms]
  Range (min … max):   407.1 ms … 411.7 ms    10 runs

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
1c56fc2084 name-rev: pre-size buffer in get_parent_name()
We can calculate the size of new name easily and precisely. Open-code
the xstrfmt() calls and grow the buffers as needed before filling them.
This provides a surprisingly large benefit when working with the
Chromium repository; here are the numbers measured using hyperfine
before:

Benchmark #1: ./git -C ../chromium/src name-rev --all
  Time (mean ± σ):      5.822 s ±  0.013 s    [User: 5.304 s, System: 0.516 s]
  Range (min … max):    5.803 s …  5.837 s    10 runs

... and with this patch:

Benchmark #1: ./git -C ../chromium/src name-rev --all
  Time (mean ± σ):      1.527 s ±  0.003 s    [User: 1.015 s, System: 0.511 s]
  Range (min … max):    1.524 s …  1.535 s    10 runs

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
ddc42ec786 name-rev: factor out get_parent_name()
Reduce nesting by moving code to come up with a name for the parent into
its own function.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
f13ca7cef5 name-rev: put struct rev_name into commit slab
The commit slab commit_rev_name contains a pointer to a struct rev_name,
and the actual struct is allocated separatly.  Avoid that allocation and
pointer indirection by storing the full struct in the commit slab.  Use
the tip_name member pointer to determine if the returned struct is
initialized.

Performance in the Linux repository measured with hyperfine before:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     953.5 ms ±   6.3 ms    [User: 901.2 ms, System: 52.1 ms]
  Range (min … max):   945.2 ms … 968.5 ms    10 runs

... and with this patch:

Benchmark #1: ./git -C ../linux/ name-rev --all
  Time (mean ± σ):     851.0 ms ±   3.1 ms    [User: 807.4 ms, System: 43.6 ms]
  Range (min … max):   846.7 ms … 857.0 ms    10 runs

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
d689d6d82f name-rev: don't _peek() in create_or_update_name()
Look up the commit slab slot for the commit once using
commit_rev_name_at() and populate it in case it is empty, instead of
checking for emptiness in a separate step using commit_rev_name_peek()
via get_commit_rev_name().

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
15a4205d96 name-rev: don't leak path copy in name_ref()
name_ref() duplicates the path string and passes it to name_rev(), which
either puts it into a commit slab or ignores it if there is already a
better name, leaking it.  Move the duplication to name_rev() and release
the copy in the latter case.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
36d2419c9a name-rev: respect const qualifier
Keep the const qualifier of the first parameter of get_rev_name() even
when casting the object pointer to a commit pointer, and further for the
parameter of get_commit_rev_name(), as all these uses are read-only.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
René Scharfe
71620ca86c name-rev: remove unused typedef
The type alias became unused with bf43abc6e6 (name-rev: use sizeof(*ptr)
instead of sizeof(type) in allocation, 2019-11-12); remove it.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:24:15 -08:00
Martin Ågren
3e2feb0d64 name-rev: rewrite create_or_update_name()
This code was moved straight out of name_rev(). As such, we inherited
the "goto" to jump from an if into an else-if. We also inherited the
fact that "nothing to do -- return NULL" is handled last.

Rewrite the function to first handle the "nothing to do" case. Then we
can handle the conditional allocation early before going on to populate
the struct. No need for goto-ing.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-05 10:23:42 -08:00
Jeff King
a21781011f index-pack: downgrade twice-resolved REF_DELTA to die()
When we're resolving a REF_DELTA, we compare-and-swap its type from
REF_DELTA to whatever real type the base object has, as discussed in
ab791dd138 (index-pack: fix race condition with duplicate bases,
2014-08-29). If the old type wasn't a REF_DELTA, we consider that a
BUG(). But as discussed in that commit, we might see this case whenever
we try to resolve an object twice, which may happen because we have
multiple copies of the base object.

So this isn't a bug at all, but rather a sign that the input pack is
broken. And indeed, this case is triggered already in t5309.5 and
t5309.6, which create packs with delta cycles and duplicate bases. But
we never noticed because those tests are marked expect_failure.

Those tests were added by b2ef3d9ebb (test index-pack on packs with
recoverable delta cycles, 2013-08-23), which was leaving the door open
for cases that we theoretically _could_ handle. And when we see an
already-resolved object like this, in theory we could keep going after
confirming that the previously resolved child->real_type matches
base->obj->real_type. But:

  - enforcing the "only resolve once" rule here saves us from an
    infinite loop in other parts of the code. If we keep going, then the
    delta cycle in t5309.5 causes us to loop infinitely, as
    find_ref_delta_children() doesn't realize which objects have already
    been resolved. So there would be more changes needed to make this
    case work, and in the meantime we'd be worse off.

  - any pack that triggers this is broken anyway. It either has a
    duplicate base object, or it has a cycle which causes us to bring in
    a duplicate via --fix-thin. In either case, we'd end up rejecting
    the pack in write_idx_file(), which also detects duplicates.

So the tests have little value in documenting what we _could_ be doing
(and have been neglected for 6+ years). Let's switch them to confirming
that we handle this case cleanly (and switch out the BUG() for a more
informative die() so that we do so).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-04 13:19:11 -08:00
Taylor Blau
a7df60cac8 commit-graph.h: use odb in 'load_commit_graph_one_fd_st'
Apply a similar treatment as in the previous patch to pass a 'struct
object_directory *' through the 'load_commit_graph_one_fd_st'
initializer, too.

This prevents a potential bug where a pointer comparison is made to a
NULL 'g->odb', which would cause the commit-graph machinery to think
that a pair of commit-graphs belonged to different alternates when in
fact they do not (i.e., in the case of no '--object-dir').

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-04 11:36:51 -08:00
Taylor Blau
ad2dd5bb63 commit-graph.c: remove path normalization, comparison
As of the previous patch, all calls to 'commit-graph.c' functions which
perform path normalization (for e.g., 'get_commit_graph_filename()') are
of the form 'ctx->odb->path', which is always in normalized form.

Now that there are no callers passing non-normalized paths to these
functions, ensure that future callers are bound by the same restrictions
by making these functions take a 'struct object_directory *' instead of
a 'const char *'. To match, replace all calls with arguments of the form
'ctx->odb->path' with 'ctx->odb' To recover the path, functions that
perform path manipulation simply use 'odb->path'.

Further, avoid string comparisons with arguments of the form
'odb->path', and instead prefer raw pointer comparisons, which
accomplish the same effect, but are far less brittle.

This has a pleasant side-effect of making these functions much more
robust to paths that cannot be normalized by 'normalize_path_copy()',
i.e., because they are outside of the current working directory.

For example, prior to this patch, Valgrind reports that the following
uninitialized memory read [1]:

  $ ( cd t && GIT_DIR=../.git valgrind git rev-parse HEAD^ )

because 'normalize_path_copy()' can't normalize '../.git' (since it's
relative to but above of the current working directory) [2].

By using a 'struct object_directory *' directly,
'get_commit_graph_filename()' does not need to normalize, because all
paths are relative to the current working directory since they are
always read from the '->path' of an object directory.

[1]: https://lore.kernel.org/git/20191027042116.GA5801@sigill.intra.peff.net.
[2]: The bug here is that 'get_commit_graph_filename()' returns the
     result of 'normalize_path_copy()' without checking the return
     value.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-04 11:36:51 -08:00
Taylor Blau
13c2499249 commit-graph.h: store object directory in 'struct commit_graph'
In a previous patch, the 'char *object_dir' in 'struct commit_graph' was
replaced with a 'struct object_directory'. This patch applies the same
treatment to 'struct commit_graph', which is another intermediate step
towards getting rid of all path normalization in 'commit-graph.c'.

Instead of taking a 'char *object_dir', functions that construct a
'struct commit_graph' now take a 'struct object_directory *'. Any code
that needs an object directory path use '->path' instead.

This ensures that all calls to functions that perform path normalization
are given arguments which do not themselves require normalization. This
prepares those functions to drop their normalization entirely, which
will occur in the subsequent patch.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-04 11:36:51 -08:00
Taylor Blau
0bd52e27e3 commit-graph.h: store an odb in 'struct write_commit_graph_context'
There are lots of places in 'commit-graph.h' where a function either has
(or almost has) a full 'struct object_directory *', accesses '->path',
and then throws away the rest of the struct.

This can cause headaches when comparing the locations of object
directories across alternates (e.g., in the case of deciding if two
commit-graph layers can be merged). These paths are normalized with
'normalize_path_copy()' which mitigates some comparison issues, but not
all [1].

Replace usage of 'char *object_dir' with 'odb->path' by storing a
'struct object_directory *' in the 'write_commit_graph_context'
structure. This is an intermediate step towards getting rid of all path
normalization in 'commit-graph.c'.

Resolving a user-provided '--object-dir' argument now requires that we
compare it to the known alternates for equality.  Prior to this patch,
an unknown '--object-dir' argument would silently exit with status zero.

This can clearly lead to unintended behavior, such as verifying
commit-graphs that aren't in a repository's own object store (or one of
its alternates), or causing a typo to mask a legitimate commit-graph
verification failure. Make this error non-silent by 'die()'-ing when the
given '--object-dir' does not match any known alternate object store.

[1]: In my testing, for example, I can get one side of the commit-graph
code to fill object_dir with "./objects" and the other with just
"objects".

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-04 11:36:37 -08:00
Derrick Stolee
e53ffe2704 sparse-checkout: escape all glob characters on write
The sparse-checkout patterns allow special globs according to
fnmatch(3). When writing cone-mode patterns for paths containing
these characters, they must be escaped.

Use is_glob_special() to check which characters must be escaped
this way, and add a path to the tests that contains all glob
characters at once. Note that ']' is not special, since the
initial bracket '[' is escaped.

Reported-by: Jeff King <peff@peff.net>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31 13:05:29 -08:00
Derrick Stolee
e55682ea26 sparse-checkout: use C-style quotes in 'list' subcommand
When in cone mode, the 'git sparse-checkout list' subcommand lists
the directories included in the sparse cone. When these directories
contain odd characters, such as a backslash, then we need to use
C-style quotes similar to 'git ls-tree'.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31 13:05:29 -08:00
Derrick Stolee
bd64de42de sparse-checkout: unquote C-style strings over --stdin
If a user somehow creates a directory with an asterisk (*) or backslash
(\), then the "git sparse-checkout set" command will struggle to provide
the correct pattern in the sparse-checkout file. When not in cone mode,
the provided pattern is written directly into the sparse-checkout file.
However, in cone mode we expect a list of paths to directories and then
we convert those into patterns.

Even more specifically, the goal is to always allow the following from
the root of a repo:

  git ls-tree --name-only -d HEAD | git sparse-checkout set --stdin

The ls-tree command provides directory names with an unescaped asterisk.
It also quotes the directories that contain an escaped backslash. We
must remove these quotes, then keep the escaped backslashes.

Use unquote_c_style() when parsing lines from stdin. Command-line
arguments will be parsed as-is, assuming the user can do the correct
level of escaping from their environment to match the exact directory
names.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31 13:05:29 -08:00
Derrick Stolee
d585f0e799 sparse-checkout: write escaped patterns in cone mode
If a user somehow creates a directory with an asterisk (*) or backslash
(\), then the "git sparse-checkout set" command will struggle to provide
the correct pattern in the sparse-checkout file. When not in cone mode,
the provided pattern is written directly into the sparse-checkout file.
However, in cone mode we expect a list of paths to directories and then
we convert those into patterns.

However, there is some care needed for the timing of these escapes. The
in-memory pattern list is used to update the working directory before
writing the patterns to disk. Thus, we need the command to have the
unescaped names in the hashsets for the cone comparisons, then escape
the patterns later.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31 13:05:29 -08:00
Junio C Hamano
145136a95a C: use skip_prefix() to avoid hardcoded string length
We often skip an optional prefix in a string with a hardcoded
constant, e.g.

	if (starts_with(string, "prefix"))
		string += 6;

which is less error prone when written

	skip_prefix(string, "prefix", &string);

Note that this changes a few error messages from "git reflog expire
--expire=nonsense.timestamp", which used to complain by saying

    '--expire=nonsense.timestamp' is not a valid timestamp

but with this change, we say

    'nonsense.timestamp' is not a valid timestamp

which is more technically correct (the string with --expire= as
a prefix obviously cannot be a valid timestamp, but the error is
about the part of the input without that prefix).

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31 13:03:45 -08:00
Matheus Tavares
b98d188581 sha1-file: allow check_object_signature() to handle any repo
Some callers of check_object_signature() can work on arbitrary
repositories, but the repo does not get passed to this function.
Instead, the_repository is always used internally. To fix possible
inconsistencies, allow the function to receive a struct repository and
make those callers pass on the repo being handled.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31 10:45:39 -08:00
Matheus Tavares
2dcde20e1c sha1-file: pass git_hash_algo to hash_object_file()
Allow hash_object_file() to work on arbitrary repos by introducing a
git_hash_algo parameter. Change callers which have a struct repository
pointer in their scope to pass on the git_hash_algo from the said repo.
For all other callers, pass on the_hash_algo, which was already being
used internally at hash_object_file(). This functionality will be used
in the following patch to make check_object_signature() be able to work
on arbitrary repos (which, in turn, will be used to fix an
inconsistency at object.c:parse_object()).

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31 10:45:39 -08:00
Matheus Tavares
c8123e72f6 streaming: allow open_istream() to handle any repo
Some callers of open_istream() at archive-tar.c and archive-zip.c are
capable of working on arbitrary repositories but the repo struct is not
passed down to open_istream(), which uses the_repository internally. For
now, that's not a problem since the said callers are only being called
with the_repository. But to be consistent and avoid future problems,
let's allow open_istream() to receive a struct repository and use that
instead of the_repository. This parameter addition will also be used in
a future patch to make sha1-file.c:check_object_signature() be able to
work on arbitrary repos.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-31 10:45:39 -08:00
Junio C Hamano
11ad30b887 Merge branch 'hi/gpg-mintrustlevel'
gpg.minTrustLevel configuration variable has been introduced to
tell various signature verification codepaths the required minimum
trust level.

* hi/gpg-mintrustlevel:
  gpg-interface: add minTrustLevel as a configuration option
2020-01-30 14:17:08 -08:00
Jonathan Tan
2df1aa239c fetch: forgo full connectivity check if --filter
If a filter is specified, we do not need a full connectivity check on
the contents of the packfile we just fetched; we only need to check that
the objects referenced are promisor objects.

This significantly speeds up fetches into repositories that have many
promisor objects, because during the connectivity check, all promisor
objects are enumerated (to mark them UNINTERESTING), and that takes a
significant amount of time.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-30 10:55:47 -08:00
Jonathan Tan
50033772d5 connected: verify promisor-ness of partial clone
Commit dfa33a298d ("clone: do faster object check for partial clones",
2019-04-21) optimized the connectivity check done when cloning with
--filter to check only the existence of objects directly pointed to by
refs. But this is not sufficient: they also need to be promisor objects.
Make this check more robust by instead checking that these objects are
promisor objects, that is, they appear in a promisor pack.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-30 10:55:31 -08:00
Philippe Blain
c56c48dd07 grep: ignore --recurse-submodules if --no-index is given
Since grep learned to recurse into submodules in 0281e487fd
(grep: optionally recurse into submodules, 2016-12-16),
using --recurse-submodules along with --no-index makes Git
die().

This is unfortunate because if submodule.recurse is set in a user's
~/.gitconfig, invoking `git grep --no-index` either inside or outside
a Git repository results in

    fatal: option not supported with --recurse-submodules

Let's allow using these options together, so that setting submodule.recurse
globally does not prevent using `git grep --no-index`.

Using `--recurse-submodules` should not have any effect if `--no-index`
is used inside a repository, as Git will recurse into the checked out
submodule directories just like into regular directories.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-30 10:15:58 -08:00
Peter Kaestle
3b2885ec9b submodule: fix status of initialized but not cloned submodules
Original bash helper for "submodule status" was doing a check for
initialized but not cloned submodules and prefixed the status with
a minus sign in case no .git file or folder was found inside the
submodule directory.

This check was missed when the original port of the functionality
from bash to C was done.

Signed-off-by: Peter Kaestle <peter.kaestle@nokia.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-27 10:14:00 -08:00
Derrick Stolee
47dbf10d8a clone: fix --sparse option with URLs
The --sparse option was added to the clone builtin in d89f09c (clone:
add --sparse mode, 2019-11-21) and was tested with a local path clone
in t1091-sparse-checkout-builtin.sh. However, due to a difference in
how local paths are handled versus URLs, this mechanism does not work
with URLs.

Modify the test to use a "file://" URL, which would output this error
before the code change:

  Cloning into 'clone'...
  fatal: cannot change to 'file://.../repo': No such file or directory
  error: failed to initialize sparse-checkout

These errors are due to using a "-C <path>" option to call 'git -C
<path> sparse-checkout init' but the URL is being given instead of
the target directory.

Update that target directory to evaluate this correctly. I have also
manually tested that https:// URLs are handled correctly as well.

Acked-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-24 13:26:54 -08:00
Derrick Stolee
3c754067a1 sparse-checkout: create leading directories
The 'git init' command creates the ".git/info" directory and fills it
with some default files. However, 'git worktree add' does not create
the info directory for that worktree. This causes a problem when running
"git sparse-checkout init" inside a worktree. While care was taken to
allow the sparse-checkout config to be specific to a worktree, this
initialization was untested.

Safely create the leading directories for the sparse-checkout file. This
is the safest thing to do even without worktrees, as a user could delete
their ".git/info" directory and expect Git to recover safely.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-24 13:26:54 -08:00
Matthew Rogers
329e6ec397 config: fix typo in variable name
In git config use of the end_null variable to determine if we should be
null terminating our output.  While it is correct to say a string is
"null terminated" the character is actually the "nul" character, so this
malapropism is being fixed.

Signed-off-by: Matthew Rogers <mattr94@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-24 10:42:13 -08:00
Alban Gruin
767a9c417e rebase -i: stop checking out the tip of the branch to rebase
One of the first things done when using a sequencer-based
rebase (ie. `rebase -i', `rebase -r', or `rebase -m') is to make a todo
list.  This requires knowledge of the commit range to rebase.  To get
the oid of the last commit of the range, the tip of the branch to rebase
is checked out with prepare_branch_to_be_rebased(), then the oid of the
head is read.  After this, the tip of the branch is not even modified.
The `am' backend, on the other hand, does not check out the branch.

On big repositories, it's a performance penalty: with `rebase -i', the
user may have to wait before editing the todo list while git is
extracting the branch silently, and "quiet" rebases will be slower than
`am'.

Since we already have the oid of the tip of the branch in
`opts->orig_head', it's useless to switch to this commit.

This removes the call to prepare_branch_to_be_rebased() in
do_interactive_rebase(), and adds a `orig_head' parameter to
get_revision_ranges().  prepare_branch_to_be_rebased() is removed as it
is no longer used.

This introduces a visible change: as we do not switch on the tip of the
branch to rebase, no reflog entry is created at the beginning of the
rebase for it.

Unscientific performance measurements, performed on linux.git, are as
follow:

  Before this patch:

    $ time git rebase -m --onto v4.18 463fa44eec2fef50~ 463fa44eec2fef50

    real    0m8,940s
    user    0m6,830s
    sys     0m2,121s

  After this patch:

    $ time git rebase -m --onto v4.18 463fa44eec2fef50~ 463fa44eec2fef50

    real    0m1,834s
    user    0m0,916s
    sys     0m0,206s

Reported-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-24 10:29:42 -08:00
Jeff King
92fb0db94c pack-objects: add checks for duplicate objects
Additional checks are added in have_duplicate_entry() and
obj_is_packed() to avoid duplicate objects in the reuse
bitmap. It was probably buggy to not have such a check
before.

Git as a client would never both asks for a tag by sha1 and
specify "include-tag", but libgit2 will, so a libgit2 client
cloning from a Git server would trigger the bug.

If a client both asks for a tag by sha1 and specifies
"include-tag", we may end up including the tag in the reuse
bitmap (due to the first thing), and then later adding it to
the packlist (due to the second). This results in duplicate
objects in the pack, which git chokes on. We should notice
that we are already including it when doing the include-tag
portion, and avoid adding it to the packlist.

The simplest place to fix this is right in add_ref_tag(),
where we could avoid peeling the tag at all if we know that
we are already including it. However, this pushes the check
instead into have_duplicate_entry(). This fixes not only
this case, but also means that we cannot have any similar
problems lurking in other code.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-23 10:51:50 -08:00
Jeff King
bb514de356 pack-objects: improve partial packfile reuse
The old code to reuse deltas from an existing packfile
just tried to dump a whole segment of the pack verbatim.
That's faster than the traditional way of actually adding
objects to the packing list, but it didn't kick in very
often. This new code is really going for a middle ground:
do _some_ per-object work, but way less than we'd
traditionally do.

The general strategy of the new code is to make a bitmap
of objects from the packfile we'll include, and then
iterate over it, writing out each object exactly as it is
in our on-disk pack, but _not_ adding it to our packlist
(which costs memory, and increases the search space for
deltas).

One complication is that if we're omitting some objects,
we can't set a delta against a base that we're not
sending. So we have to check each object in
try_partial_reuse() to make sure we have its delta.

About performance, in the worst case we might have
interleaved objects that we are sending or not sending,
and we'd have as many chunks as objects. But in practice
we send big chunks.

For instance, packing torvalds/linux on GitHub servers
now reused 6.5M objects, but only needed ~50k chunks.

Helped-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-23 10:51:50 -08:00
Jeff King
ff483026a9 builtin/pack-objects: introduce obj_is_packed()
Let's refactor the way we check if an object is packed by
introducing obj_is_packed(). This function is now a simple
wrapper around packlist_find(), but it will evolve in a
following commit.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-23 10:51:50 -08:00
Jeff King
e704fc7978 pack-objects: introduce pack.allowPackReuse
Let's make it possible to configure if we want pack reuse or not.

The main reason it might not be wanted is probably debugging and
performance testing, though pack reuse _might_ cause larger packs,
because we wouldn't consider the reused objects as bases for
finding new deltas.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-23 10:51:50 -08:00
Junio C Hamano
09e393d913 Merge branch 'nd/switch-and-restore'
"git restore --staged" did not correctly update the cache-tree
structure, resulting in bogus trees to be written afterwards, which
has been corrected.

* nd/switch-and-restore:
  restore: invalidate cache-tree when removing entries with --staged
2020-01-22 15:07:32 -08:00
Junio C Hamano
9403e5dcdd Merge branch 'hw/commit-advise-while-rejecting'
"git commit" gives output similar to "git status" when there is
nothing to commit, but without honoring the advise.statusHints
configuration variable, which has been corrected.

* hw/commit-advise-while-rejecting:
  commit: honor advice.statusHints when rejecting an empty commit
2020-01-22 15:07:30 -08:00
Elijah Newren
22a69fda19 git-rebase.txt: update description of --allow-empty-message
Commit b00bf1c9a8 ("git-rebase: make --allow-empty-message the
default", 2018-06-27) made --allow-empty-message the default and thus
turned --allow-empty-message into a no-op but did not update the
documentation to reflect this.  Update the documentation now, and hide
the option from the normal -h output since it is not useful.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-17 13:58:30 -08:00
Matheus Tavares
f1928f04b2 grep: use no. of cores as the default no. of threads
When --threads is not specified, git-grep will use 8 threads by default.
This fixed number may be too many for machines with fewer cores and too
little for machines with more cores. So, instead, use the number of
logical cores available in the machine, which seems to result in the
best overall performance: The following measurements correspond to the
mean elapsed times for 30 git-grep executions in chromium's
repository[1] with a 95% confidence interval (each set of 30 were
performed after 2 warmup runs). Regex 1 is 'abcd[02]' and Regex 2 is
'(static|extern) (int|double) \*'.

      |          Working tree         |           Object Store
------|-------------------------------|--------------------------------
 #ths |  Regex 1      |  Regex 2      |   Regex 1      |   Regex 2
------|---------------|---------------|----------------|---------------
  32  |  2.92s ± 0.01 |  3.72s ± 0.21 |   5.36s ± 0.01 |   6.07s ± 0.01
  16  |  2.84s ± 0.01 |  3.57s ± 0.21 |   5.05s ± 0.01 |   5.71s ± 0.01
>  8  |  2.53s ± 0.00 |  3.24s ± 0.21 |   4.86s ± 0.01 |   5.48s ± 0.01
   4  |  2.43s ± 0.02 |  3.22s ± 0.20 |   5.22s ± 0.02 |   6.03s ± 0.02
   2  |  3.06s ± 0.20 |  4.52s ± 0.01 |   7.52s ± 0.01 |   9.06s ± 0.01
   1  |  6.16s ± 0.01 |  9.25s ± 0.02 |  14.10s ± 0.01 |  17.22s ± 0.01

The above tests were performed in a desktop running Debian 10.0 with
Intel(R) Xeon(R) CPU E3-1230 V2 (4 cores w/ hyper-threading), 32GB of
RAM and a 7200 rpm, SATA 3.1 HDD.

Bellow, the tests were repeated for a machine with SSD: a Manjaro laptop
with Intel(R) i7-7700HQ (4 cores w/ hyper-threading) and 16GB of RAM:

      |          Working tree          |           Object Store
------|--------------------------------|--------------------------------
 #ths |  Regex 1      |  Regex 2       |   Regex 1      |   Regex 2
------|---------------|----------------|----------------|---------------
  32  |  3.29s ± 0.21 |   4.30s ± 0.01 |   6.30s ± 0.01 |   7.30s ± 0.02
  16  |  3.19s ± 0.20 |   4.14s ± 0.02 |   5.91s ± 0.01 |   6.83s ± 0.01
>  8  |  2.90s ± 0.04 |   3.82s ± 0.20 |   5.70s ± 0.02 |   6.53s ± 0.01
   4  |  2.84s ± 0.02 |   3.77s ± 0.20 |   6.19s ± 0.02 |   7.18s ± 0.02
   2  |  3.73s ± 0.21 |   5.57s ± 0.02 |   9.28s ± 0.01 |  11.22s ± 0.01
   1  |  7.48s ± 0.02 |  11.36s ± 0.03 |  17.75s ± 0.01 |  21.87s ± 0.08

[1]: chromium’s repo at commit 03ae96f (“Add filters testing at DSF=2”,
     04-06-2019), after a 'git gc' execution.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-17 13:52:15 -08:00
Matheus Tavares
70a9fef240 grep: move driver pre-load out of critical section
In builtin/grep.c:add_work() we pre-load the userdiff drivers before
adding the grep_source in the todo list. This operation is currently
being performed after acquiring the grep_mutex, but as it's already
thread-safe, we don't need to protect it here. So let's move it out of
the critical section which should avoid thread contention and improve
performance.

Running[1] `git grep --threads=8 abcd[02] HEAD` on chromium's
repository[2], I got the following mean times for 30 executions after 2
warmups:

        Original         |  6.2886s
-------------------------|-----------
 Out of critical section |  5.7852s

[1]: Tests performed on an i7-7700HQ with 16GB of RAM and SSD, running
     Manjaro Linux.
[2]: chromium’s repo at commit 03ae96f (“Add filters testing at DSF=2”,
         04-06-2019), after a 'git gc' execution.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-17 13:52:14 -08:00
Matheus Tavares
1184a95ea2 grep: re-enable threads in non-worktree case
They were disabled at 53b8d93 ("grep: disable threading in non-worktree
case", 12-12-2011), due to observable performance drops (to the point
that using a single thread would be faster than multiple threads). But
now that zlib inflation can be performed in parallel we can regain the
speedup, so let's re-enable threads in non-worktree grep.

Grepping 'abcd[02]' ("Regex 1") and '(static|extern) (int|double) \*'
("Regex 2") at chromium's repository[1] I got:

 Threads |   Regex 1  |  Regex 2
---------|------------|-----------
    1    |  17.2920s  |  20.9624s
    2    |   9.6512s  |  11.3184s
    4    |   6.7723s  |   7.6268s
    8**  |   6.2886s  |   6.9843s

These are all means of 30 executions after 2 warmup runs. All tests were
executed on an i7-7700HQ (quad-core w/ hyper-threading), 16GB of RAM and
SSD, running Manjaro Linux. But to make sure the optimization also
performs well on HDD, the tests were repeated on another machine with an
i5-4210U (dual-core w/ hyper-threading), 8GB of RAM and HDD (SATA III,
5400 rpm), also running Manjaro Linux:

 Threads |   Regex 1  |  Regex 2
---------|------------|-----------
    1    |  18.4035s  |  22.5368s
    2    |  12.5063s  |  14.6409s
    4**  |  10.9136s  |  12.7106s

** Note that in these cases we relied on hyper-threading, and that's
   probably why we don't see a big difference in time.

Unfortunately, multithreaded git-grep might be slow in the non-worktree
case when --textconv is used and there're too many text conversions.
Probably the reason for this is that the object read lock is used to
protect fill_textconv() and therefore there is a mutual exclusion
between textconv execution and object reading. Because both are
time-consuming operations, not being able to perform them in parallel
can cause performance drops. To inform the users about this (and other
threading details), let's also add a "NOTES ON THREADS" section to
Documentation/git-grep.txt.

[1]: chromium’s repo at commit 03ae96f (“Add filters testing at DSF=2”,
     04-06-2019), after a 'git gc' execution.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-17 13:52:14 -08:00
Matheus Tavares
6c307626f1 grep: protect packed_git [re-]initialization
Some fields in struct raw_object_store are lazy initialized by the
thread-unsafe packfile.c:prepare_packed_git(). Although this function is
present in the call stack of git-grep threads, all paths to it are
currently protected by obj_read_lock() (and the main thread usually
indirectly calls it before firing the worker threads, anyway). However,
it's possible that future modifications add new unprotected paths to it,
introducing a race condition. Because errors derived from it wouldn't
happen often, it could be hard to detect. So to prevent future
headaches, let's force eager initialization of packed_git when setting
git-grep up. There'll be a small overhead in the cases where we didn't
really need to prepare packed_git during execution but this shouldn't be
very noticeable.

Also, packed_git may be re-initialized by
packfile.c:reprepare_packed_git(). Again, all paths to it in git-grep
are already protected by obj_read_lock() but it may suffer from the same
problem in the future. So let's also internally protect it with
obj_read_lock() (which is a recursive mutex).

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-17 13:52:14 -08:00
Matheus Tavares
c441ea4edc grep: allow submodule functions to run in parallel
Now that object reading operations are internally protected, the
submodule initialization functions at builtin/grep.c:grep_submodule()
are very close to being thread-safe. Let's take a look at each call and
remove from the critical section what we can, for better performance:

- submodule_from_path() and is_submodule_active() cannot be called in
  parallel yet only because they call repo_read_gitmodules() which
  contains, in its call stack, operations that would otherwise be in
  race condition with object reading (for example parse_object() and
  is_promisor_remote()). However, they only call repo_read_gitmodules()
  if it wasn't read before. So let's pre-read it before firing the
  threads and allow these two functions to safely be called in
  parallel.

- repo_submodule_init() is already thread-safe, so remove it from the
  critical section without other necessary changes.

- The repo_read_gitmodules(&subrepo) call at grep_submodule() is safe as
  no other thread is performing object reading operations in the subrepo
  yet. However, threads might be working in the superproject, and this
  function calls add_to_alternates_memory() internally, which is racy
  with object readings in the superproject. So it must be kept
  protected for now. Let's add a "NEEDSWORK" to it, informing why it
  cannot be removed from the critical section yet.

- Finally, add_to_alternates_memory() must be kept protected for the
  same reason as the item above.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-17 13:52:14 -08:00
Matheus Tavares
d7992421e1 submodule-config: add skip_if_read option to repo_read_gitmodules()
Currently, submodule-config.c doesn't have an externally accessible
function to read gitmodules only if it wasn't already read. But this
exact behavior is internally implemented by gitmodules_read_check(), to
perform a lazy load. Let's merge this function with
repo_read_gitmodules() adding a 'skip_if_read' which allows both
internal and external callers to access this functionality. This
simplifies a little the code. The added option will also be used in
the following patch.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-17 13:52:14 -08:00
Matheus Tavares
1d1729caeb grep: replace grep_read_mutex by internal obj read lock
git-grep uses 'grep_read_mutex' to protect its calls to object reading
operations. But these have their own internal lock now, which ensures a
better performance (allowing parallel access to more regions). So, let's
remove the former and, instead, activate the latter with
enable_obj_read_lock().

Sections that are currently protected by 'grep_read_mutex' but are not
internally protected by the object reading lock should be surrounded by
obj_read_lock() and obj_read_unlock(). These guarantee mutual exclusion
with object reading operations, keeping the current behavior and
avoiding race conditions. Namely, these places are:

  In grep.c:

  - fill_textconv() at fill_textconv_grep().
  - userdiff_get_textconv() at grep_source_1().

  In builtin/grep.c:

  - parse_object_or_die() and the submodule functions at
    grep_submodule().
  - deref_tag() and gitmodules_config_oid() at grep_objects().

If these functions become thread-safe, in the future, we might remove
the locking and probably get some speedup.

Note that some of the submodule functions will already be thread-safe
(or close to being thread-safe) with the internal object reading lock.
However, as some of them will require additional modifications to be
removed from the critical section, this will be done in its own patch.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-17 13:52:14 -08:00
Matheus Tavares
d5b0bac528 grep: fix racy calls in grep_objects()
deref_tag() calls is_promisor_object() and parse_object(), both of which
perform lazy initializations and other thread-unsafe operations. If it
was only called by grep_objects() this wouldn't be a problem as the
latter is only executed by the main thread. However, deref_tag() is also
present in read_object_file()'s call stack. So calling deref_tag() in
grep_objects() without acquiring the grep_read_mutex may incur in a race
condition with object reading operations (such as the ones internally
performed by fill_textconv(), called at fill_textconv_grep()). The same
problem happens with the call to gitmodules_config_oid() which also has
parse_object() in its call stack. Fix that protecting both calls with
the said grep_read_mutex.

Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-17 13:52:14 -08:00