Commit Graph

114 Commits

Author SHA1 Message Date
Victoria Dye
35682ada44 checkout-index: integrate with sparse index
Add repository settings to allow usage of the sparse index.

When using the `--all` option, sparse directories are ignored by default due
to the `skip-worktree` flag, so there is no need to expand the index. If
`--ignore-skip-worktree-bits` is specified, the index is expanded in order
to check out all files.

When checking out individual files, existing behavior in a full index is to
exit with an error if a directory is specified (as the directory name will
not match an index entry). However, it is possible in a sparse index to
match a directory name to a sparse directory index entry, but checking out
that sparse directory still results in an error on checkout. To reduce some
potential confusion for users, `checkout_file(...)` explicitly exits with an
informative error if provided with a sparse directory name. The test
corresponding to this scenario verifies the error message, which now differs
between sparse index and non-sparse index checkouts.

Signed-off-by: Victoria Dye <vdye@github.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-13 13:49:45 -08:00
Victoria Dye
88078f543b checkout-index: add --ignore-skip-worktree-bits option
Update `checkout-index` to no longer refresh files that have the
`skip-worktree` bit set, exiting with an error if `skip-worktree` filenames
are directly provided to `checkout-index`. The newly-added
`--ignore-skip-worktree-bits` option provides a mechanism to replicate the
old behavior, checking out *all* files specified (even those with
`skip-worktree` enabled).

The ability to toggle whether files should be checked-out based on
`skip-worktree` already exists in `git checkout` and `git restore` (both of
which have an `--ignore-skip-worktree-bits` option). The change to, by
default, ignore `skip-worktree` files is especially helpful for
sparse-checkout; it prevents inadvertent creation of files outside the
sparse definition on disk and eliminates the need to expand a sparse index
when using the `--all` option.

Internal usage of `checkout-index` in `git stash` and `git filter-branch` do
not make explicit use of files with `skip-worktree` enabled, so
`--ignore-skip-worktree-bits` is not added to them.

Helped-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Victoria Dye <vdye@github.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-13 13:49:45 -08:00
Victoria Dye
b553ef6749 checkout-index: expand sparse checkout compatibility tests
Add tests to cover `checkout-index`, with a focus on cases interesting in a
sparse checkout (e.g., files specified outside sparse checkout definition).

New tests are intended to serve as a baseline for existing and/or expected
behavior and performance when integrating `checkout-index` with the sparse
index. Note that the test 'checkout-index --all' is marked as
'test_expect_failure', indicating that `update-index --all` will be modified
in a subsequent patch to behave as the test expects.

Signed-off-by: Victoria Dye <vdye@github.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-13 13:49:45 -08:00
Victoria Dye
1e9e10e048 clean: integrate with sparse index
Remove full index requirement for `git clean` and test to ensure the index
is not expanded in `git clean`. Add to existing test for `git clean` to
verify cleanup of untracked files in sparse directories is consistent
between sparse index and non-sparse index checkouts.

Signed-off-by: Victoria Dye <vdye@github.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-13 13:49:45 -08:00
Victoria Dye
bb01b26dec reset: fix validation in sparse index test
Update t1092 test 'reset with pathspecs outside sparse definition' to verify
index contents. The use of `rev-parse` verifies the contents of HEAD, not
the index, providing no real validation of the reset results. Conversely,
`ls-files` reports the contents of the index (OIDs, flags, filenames), which
are then compared across checkouts to ensure compatible index states.

Fixes 741a2c9ffa (reset: expand test coverage for sparse checkouts,
2021-09-27).

Signed-off-by: Victoria Dye <vdye@github.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-13 13:49:44 -08:00
Derrick Stolee
3a9a6ac5d9 t1092: replace 'read-cache --table' with 'ls-files --sparse'
Now that 'git ls-files --sparse' exists, we can use it to verify the
state of a sparse index instead of 'test-tool read-cache table'. Replace
these usages within t1092-sparse-checkout-compatibility.sh.

The important changes are due to the different output format. We need to
use the '--stage' output to get a file mode and OID, but it also
includes a stage value and drops the object type. This leads to some
differences in how we handle looking for specific entries.

Some places where we previously looked for no 'tree' entries, we can
instead directly compare the output across the repository with a sparse
index and the one without.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-22 11:42:40 -08:00
Derrick Stolee
78087097b8 ls-files: add --sparse option
Existing callers to 'git ls-files' are expecting file names, not
directories. It is best to expand a sparse index to show all of the
contained files in this case.

However, expert users may want to inspect the contents of the index
itself including which directories are sparse. Add a --sparse option to
allow users to request this information.

During testing, I noticed that options such as --modified did not affect
the output when the files in question were outside the sparse-checkout
definition. Tests are added to document this preexisting behavior and
how it remains unchanged with the sparse index and the --sparse option.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-22 11:42:40 -08:00
Derrick Stolee
5a4e0547e2 fetch/pull: use the sparse index
The 'git fetch' and 'git pull' commands parse the index in order to
determine if submodules exist. Without command_requires_full_index=0,
this will expand a sparse index, causing slow performance even when
there is no new data to fetch.

The .gitmodules file will never be inside a sparse directory entry, and
even if it was, the index_name_pos() method would expand the sparse
index if needed as we search for the path by name. These commands do not
iterate over the index, which is the typical thing we are careful about
when integrating with the sparse index.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-22 11:42:39 -08:00
Junio C Hamano
8d2c37320b Merge branch 'ld/sparse-diff-blame'
Teach diff and blame to work well with sparse index.

* ld/sparse-diff-blame:
  blame: enable and test the sparse index
  diff: enable and test the sparse index
  diff: replace --staged with --cached in t1092 tests
  repo-settings: prepare_repo_settings only in git repos
  test-read-cache: set up repo after git directory
  commit-graph: return if there is no git directory
  git: ensure correct git directory setup with -h
2021-12-21 15:03:17 -08:00
Junio C Hamano
e1d9288267 Merge branch 'ds/sparse-deep-pattern-checkout-fix'
The sparse-index/sparse-checkout feature had a bug in its use of
the matching code to determine which path is in or outside the
sparse checkout patterns.

* ds/sparse-deep-pattern-checkout-fix:
  unpack-trees: use traverse_path instead of name
  t1092: add deeper changes during a checkout
2021-12-15 09:39:50 -08:00
Junio C Hamano
62329d336f Merge branch 'ds/trace2-regions-in-tests'
The default setting for trace2 event nesting was too low to cause
test failures, which is worked around by bumping it up in the test
framework.

* ds/trace2-regions-in-tests:
  t/t*: remove custom GIT_TRACE2_EVENT_NESTING
  test-lib.sh: set GIT_TRACE2_EVENT_NESTING
2021-12-15 09:39:46 -08:00
Junio C Hamano
f0850875fd Merge branch 'vd/sparse-reset'
Various operating modes of "git reset" have been made to work
better with the sparse index.

* vd/sparse-reset:
  unpack-trees: improve performance of next_cache_entry
  reset: make --mixed sparse-aware
  reset: make sparse-aware (except --mixed)
  reset: integrate with sparse index
  reset: expand test coverage for sparse checkouts
  sparse-index: update command for expand/collapse test
  reset: preserve skip-worktree bit in mixed reset
  reset: rename is_missing to !is_in_reset_tree
2021-12-10 14:35:12 -08:00
Junio C Hamano
5396d7b298 Merge branch 'vd/sparse-sparsity-fix-on-read'
Ensure that the sparseness of the in-core index matches the
index.sparse configuration specified by the repository immediately
after the on-disk index file is read.

* vd/sparse-sparsity-fix-on-read:
  sparse-index: update do_read_index to ensure correct sparsity
  sparse-index: add ensure_correct_sparsity function
  sparse-index: avoid unnecessary cache tree clearing
  test-read-cache.c: prepare_repo_settings after config init
2021-12-10 14:35:01 -08:00
Lessley Dennington
add4c864b6 blame: enable and test the sparse index
Enable the sparse index for the 'git blame' command. The index was already
not expanded with this command, so the most interesting thing to do is to
add tests that verify that 'git blame' behaves correctly when the sparse
index is enabled and that its performance improves. More specifically, these
cases are:

1. The index is not expanded for 'blame' when given paths in the sparse
checkout cone at multiple levels.

2. Performance measurably improves for 'blame' with sparse index when given
paths in the sparse checkout cone at multiple levels.

The `p2000` tests demonstrate a ~60% execution time reduction when running
'blame' for a file two levels deep and and a ~30% execution time reduction
for a file three levels deep.

Test                                         before  after
----------------------------------------------------------------
2000.62: git blame f2/f4/a (full-v3)         0.31    0.32 +3.2%
2000.63: git blame f2/f4/a (full-v4)         0.29    0.31 +6.9%
2000.64: git blame f2/f4/a (sparse-v3)       0.55    0.23 -58.2%
2000.65: git blame f2/f4/a (sparse-v4)       0.57    0.23 -59.6%
2000.66: git blame f2/f4/f3/a (full-v3)      0.77    0.85 +10.4%
2000.67: git blame f2/f4/f3/a (full-v4)      0.78    0.81 +3.8%
2000.68: git blame f2/f4/f3/a (sparse-v3)    1.07    0.72 -32.7%
2000.99: git blame f2/f4/f3/a (sparse-v4)    1.05    0.73 -30.5%

We do not include paths outside the sparse checkout cone because blame
does not support blaming files that are not present in the working
directory. This is true in both sparse and full checkouts.

Signed-off-by: Lessley Dennington <lessleydennington@gmail.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-06 09:55:06 -08:00
Lessley Dennington
51ba65b5c3 diff: enable and test the sparse index
Enable the sparse index within the 'git diff' command. Its implementation
already safely integrates with the sparse index because it shares code
with the 'git status' and 'git checkout' commands that were already
integrated.  For more details see:

d76723ee53 (status: use sparse-index throughout, 2021-07-14)
1ba5f45132 (checkout: stop expanding sparse indexes, 2021-06-29)

The most interesting thing to do is to add tests that verify that 'git
diff' behaves correctly when the sparse index is enabled. These cases are:

1. The index is not expanded for 'diff' and 'diff --staged'
2. 'diff' and 'diff --staged' behave the same in full checkout, sparse
checkout, and sparse index repositories in the following partially-staged
scenarios (i.e. the index, HEAD, and working directory differ at a given
path):
    1. Path is within sparse-checkout cone
    2. Path is outside sparse-checkout cone
    3. A merge conflict exists for paths outside sparse-checkout cone

The `p2000` tests demonstrate a ~44% execution time reduction for 'git
diff' and a ~86% execution time reduction for 'git diff --staged' using a
sparse index:

Test                                      before  after
-------------------------------------------------------------
2000.30: git diff (full-v3)               0.33    0.34 +3.0%
2000.31: git diff (full-v4)               0.33    0.35 +6.1%
2000.32: git diff (sparse-v3)             0.53    0.31 -41.5%
2000.33: git diff (sparse-v4)             0.54    0.29 -46.3%
2000.34: git diff --cached (full-v3)      0.07    0.07 +0.0%
2000.35: git diff --cached (full-v4)      0.07    0.08 +14.3%
2000.36: git diff --cached (sparse-v3)    0.28    0.04 -85.7%
2000.37: git diff --cached (sparse-v4)    0.23    0.03 -87.0%

Co-authored-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Lessley Dennington <lessleydennington@gmail.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-06 09:55:06 -08:00
Lessley Dennington
338e2a9acc diff: replace --staged with --cached in t1092 tests
Replace uses of the synonym --staged in t1092 tests with --cached (which
is the real and preferred option). This will allow consistency in the new
tests to be added with the upcoming change to enable the sparse index for
diff.

Signed-off-by: Lessley Dennington <lessleydennington@gmail.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-06 09:55:06 -08:00
Derrick Stolee
8c5de0d265 unpack-trees: use traverse_path instead of name
The sparse_dir_matches_path() method compares a cache entry that is a
sparse directory entry against a 'struct traverse_info *info' and a
'struct name_entry *p' to see if the cache entry has exactly the right
name for those other inputs.

This method was introduced in 523506d (unpack-trees: unpack sparse
directory entries, 2021-07-14), but included a significant mistake. The
path comparisons used 'info->name' instead of 'info->traverse_path'.
Since 'info->name' only stores a single tree entry name while
'info->traverse_path' stores the full path from root, this method does
not work when 'info' is in a subdirectory of a directory. Replacing the
right strings and their corresponding lengths make the method work
properly.

The previous change included a failing test that exposes this issue.
That test now passes. The critical detail is that as we go deep into
unpack_trees(), the logic for merging a sparse directory entry with a
tree entry during 'git checkout' relies on this
sparse_dir_matches_path() in order to avoid calling
traverse_trees_recursive() during unpack_callback() in this hunk:

	if (!is_sparse_directory_entry(src[0], names, info) &&
	    traverse_trees_recursive(n, dirmask, mask & ~dirmask,
					    names, info) < 0) {
		return -1;
	}

For deep paths, the short-circuit never occurred and
traverse_trees_recursive() was being called incorrectly and that was
causing other strange issues. Specifically, the error message from the
now-passing test previously included this:

      error: Your local changes to the following files would be overwritten by checkout:
              deep/deeper1/deepest2/a
              deep/deeper1/deepest3/a
      Please commit your changes or stash them before you switch branches.
      Aborting

These messages occurred because the 'current' cache entry in
twoway_merge() was showing as NULL because the index did not contain
entries for the paths contained within the sparse directory entries. We
instead had 'oldtree' given as the entry at HEAD and 'newtree' as the
entry in the target tree. This led to reject_merge() listing these
paths.

Now that sparse_dir_matches_path() works the same for deep paths as it
does for shallow depths, the rest of the logic kicks in to properly
handle modifying the sparse directory entries as designed.

Reported-by: Gustave Granroth <gus.gran@gmail.com>
Reported-by: Mike Marcelais <michmarc@exchange.microsoft.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-06 09:24:54 -08:00
Derrick Stolee
1b38efc7a0 t1092: add deeper changes during a checkout
Extend the repository data in the setup of t1092 to include more
directories within two parent directories. This reproduces a bug found
by users of the sparse index feature with suitably-complicated
sparse-checkout definitions.

Add a failing test that fails in its first 'git checkout deepest' run in
the sparse index case with this error:

  error: Your local changes to the following files would be overwritten by checkout:
          deep/deeper1/deepest2/a
          deep/deeper1/deepest3/a
  Please commit your changes or stash them before you switch branches.
  Aborting

The next change will fix this error, and that fix will make it clear why
the extra depth is necessary for revealing this bug. The assignment of
the sparse-checkout definition to include deep/deeper1/deepest as a
sibling directory is important to ensure that deep/deeper1 is not a
sparse directory entry, but deep/deeper1/deepest2 is.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-06 09:24:53 -08:00
Junio C Hamano
ea6ae410be Merge branch 'vd/sparse-reset' into ld/sparse-diff-blame
* vd/sparse-reset:
  unpack-trees: improve performance of next_cache_entry
  reset: make --mixed sparse-aware
  reset: make sparse-aware (except --mixed)
  reset: integrate with sparse index
  reset: expand test coverage for sparse checkouts
  sparse-index: update command for expand/collapse test
  reset: preserve skip-worktree bit in mixed reset
  reset: rename is_missing to !is_in_reset_tree
2021-11-29 12:53:56 -08:00
Victoria Dye
4d1cfc1351 reset: make --mixed sparse-aware
Remove the `ensure_full_index` guard on `read_from_tree` and update `git
reset --mixed` to ensure it can use sparse directory index entries wherever
possible. Sparse directory entries are reset using `diff_tree_oid`, which
requires `change` and `add_remove` functions to process the internal
contents of the sparse directory. The `recursive` diff option handles cases
in which `reset --mixed` must diff/merge files that are nested multiple
levels deep in a sparse directory.

The use of pathspecs with `git reset --mixed` introduces scenarios in which
internal contents of sparse directories may be matched by the pathspec. In
order to reset *all* files in the repo that may match the pathspec, the
following conditions on the pathspec require index expansion before
performing the reset:

* "magic" pathspecs
* wildcard pathspecs that do not match only in-cone files or entire sparse
  directories
* literal pathspecs matching something outside the sparse checkout
  definition

Helped-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-11-29 12:51:26 -08:00
Victoria Dye
20ec2d034c reset: make sparse-aware (except --mixed)
Remove `ensure_full_index` guard on `prime_cache_tree` and update
`prime_cache_tree_rec` to correctly reconstruct sparse directory entries in
the cache tree. While processing a tree's entries, `prime_cache_tree_rec`
must determine whether a directory entry is sparse or not by searching for
it in the index (*without* expanding the index). If a matching sparse
directory index entry is found, no subtrees are added to the cache tree
entry and the entry count is set to 1 (representing the sparse directory
itself). Otherwise, the tree is assumed to not be sparse and its subtrees
are recursively added to the cache tree.

Helped-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-11-29 12:51:26 -08:00
Victoria Dye
291d77eb3e reset: expand test coverage for sparse checkouts
Add new tests for `--merge` and `--keep` modes, as well as mixed reset with
pathspecs. New performance test cases exercise various execution paths for
`reset`.

Co-authored-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-11-29 12:51:26 -08:00
Derrick Stolee
8c4cbad6a3 t/t*: remove custom GIT_TRACE2_EVENT_NESTING
The previous change modified GIT_TRACE2_EVENT_NESTING by default within
test-lib.sh. These custom assignments throughout the test suite are no
longer necessary.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-11-29 10:23:50 -08:00
Victoria Dye
7ca4fc8819 sparse-index: update do_read_index to ensure correct sparsity
Unless `command_requires_full_index` forces index expansion, ensure in-core
index sparsity matches config settings on read by calling
`ensure_correct_sparsity`. This makes the behavior of the in-core index more
consistent between different methods of updating sparsity: manually changing
the `index.sparse` config setting vs. executing
`git sparse-checkout --[no-]sparse-index init`

Although index sparsity is normally updated with `git sparse-checkout init`,
ensuring correct sparsity after a manual `index.sparse` change has some
practical benefits:

1. It allows for command-by-command sparsity toggling with
   `-c index.sparse=<true|false>`, e.g. when troubleshooting issues with the
   sparse index.
2. It prevents users from experiencing abnormal slowness after setting
   `index.sparse` to `true` due to use of a full index in all commands until
   the on-disk index is updated.

Helped-by: Junio C Hamano <gitster@pobox.com>
Co-authored-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Victoria Dye <vdye@github.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-11-24 16:32:39 -08:00
Victoria Dye
86609db9da sparse-index: update command for expand/collapse test
In anticipation of `git reset --hard` being able to use the sparse index
without expanding it, replace the command in `sparse-index is expanded and
converted back` with `git reset -- folder1/a`. This command will need to
expand the index to work properly, even after integrating the rest of
`reset` with sparse index.

Helped-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-27 15:05:11 -07:00
Victoria Dye
71471b2a7c reset: preserve skip-worktree bit in mixed reset
Change `update_index_from_diff` to set `skip-worktree` when applicable for
new index entries. When `git reset --mixed <tree-ish>` is run, entries in
the index with differences between the pre-reset HEAD and reset <tree-ish>
are identified and handled with `update_index_from_diff`. For each file, a
new cache entry in inserted into the index, created from the <tree-ish> side
of the reset (without changing the working tree). However, the newly-created
entry must have `skip-worktree` explicitly set in either of the following
scenarios:

1. the file is in the current index and has `skip-worktree` set
2. the file is not in the current index but is outside of a defined sparse
   checkout definition

Not setting the `skip-worktree` bit leads to likely-undesirable results for
a user. It causes `skip-worktree` settings to disappear on the
"diff"-containing files (but *only* the diff-containing files), leading to
those files now showing modifications in `git status`. For example, when
running `git reset --mixed` in a sparse checkout, some file entries outside
of sparse checkout could show up as deleted, despite the user never deleting
anything (and not wanting them on-disk anyway).

Additionally, add a test to `t7102` to ensure `skip-worktree` is preserved
in a basic `git reset --mixed` scenario and update a failure-documenting
test from 19a0acc (t1092: test interesting sparse-checkout scenarios,
2021-01-23) with new expected behavior.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-27 15:05:11 -07:00
Junio C Hamano
e058b1846c Merge branch 'pw/sparse-cache-tree-verify-fix'
Recent sparse-index addition, namely any use of index_name_pos(),
can expand sparse index entries and breaks any code that walks
cache-tree or existing index entries.  One such instance of such a
breakage has been corrected.

* pw/sparse-cache-tree-verify-fix:
  t1092: run "rebase --apply" without "-q" in testing
  sparse index: fix use-after-free bug in cache_tree_verify()
2021-10-25 16:06:57 -07:00
Phillip Wood
5e311edfd3 t1092: run "rebase --apply" without "-q" in testing
We run a few operations and make sure they produce identical results
with and without sparse-index; the version we merged to the "next"
branch used the "-q" option to work around a breakage caused by a
version used at Microsoft with some unreleased changes, but since
we would want to make sure the commands produce identical results,
including reports given to the output that lists which commits were
picked, use of "-q" loses too much interesting information.

Let's drop "-q" from the command invocation and revisit the issue
when the problematic changes are upstreamed.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Helped-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-18 09:24:51 -07:00
Phillip Wood
f751097be3 sparse index: fix use-after-free bug in cache_tree_verify()
In a sparse index it is possible for the tree that is being verified
to be freed while it is being verified. This happens when the index is
sparse but the cache tree is not and index_name_pos() looks up a path
from the cache tree that is a descendant of a sparse index entry. That
triggers a call to ensure_full_index() which frees the cache tree that
is being verified.  Carrying on trying to verify the tree after this
results in a use-after-free bug. Instead restart the verification if a
sparse index is converted to a full index. This bug is triggered by a
call to reset_head() in "git rebase --apply". Thanks to René Scharfe
and Derrick Stolee for their help analyzing the problem.

==74345==ERROR: AddressSanitizer: heap-use-after-free on address 0x606000001b20 at pc 0x557cbe82d3a2 bp 0x7ffdfee08090 sp 0x7ffdfee08080
READ of size 4 at 0x606000001b20 thread T0
    #0 0x557cbe82d3a1 in verify_one /home/phil/src/git/cache-tree.c:863
    #1 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #2 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #3 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #4 0x557cbe830a2b in cache_tree_verify /home/phil/src/git/cache-tree.c:910
    #5 0x557cbea53741 in write_locked_index /home/phil/src/git/read-cache.c:3250
    #6 0x557cbeab7fdd in reset_head /home/phil/src/git/reset.c:87
    #7 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
    #8 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
    #9 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
    #10 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
    #11 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
    #12 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
    #13 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
    #14 0x557cbe5bcb8d in _start (/home/phil/src/git/git+0x1b9b8d)

0x606000001b20 is located 0 bytes inside of 56-byte region [0x606000001b20,0x606000001b58)
freed by thread T0 here:
    #0 0x7fdd4bacff19 in __interceptor_free /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:127
    #1 0x557cbe82af60 in cache_tree_free /home/phil/src/git/cache-tree.c:35
    #2 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
    #3 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
    #4 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
    #5 0x557cbeb2557a in ensure_full_index /home/phil/src/git/sparse-index.c:310
    #6 0x557cbea45c4a in index_name_stage_pos /home/phil/src/git/read-cache.c:588
    #7 0x557cbe82ce37 in verify_one /home/phil/src/git/cache-tree.c:850
    #8 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #9 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #10 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
    #11 0x557cbe830a2b in cache_tree_verify /home/phil/src/git/cache-tree.c:910
    #12 0x557cbea53741 in write_locked_index /home/phil/src/git/read-cache.c:3250
    #13 0x557cbeab7fdd in reset_head /home/phil/src/git/reset.c:87
    #14 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
    #15 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
    #16 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
    #17 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
    #18 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
    #19 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
    #20 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)

previously allocated by thread T0 here:
    #0 0x7fdd4bad0459 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
    #1 0x557cbebc1807 in xcalloc /home/phil/src/git/wrapper.c:140
    #2 0x557cbe82b7d8 in cache_tree /home/phil/src/git/cache-tree.c:17
    #3 0x557cbe82b7d8 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:763
    #4 0x557cbe82b837 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:764
    #5 0x557cbe82b837 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:764
    #6 0x557cbe8304e1 in prime_cache_tree /home/phil/src/git/cache-tree.c:779
    #7 0x557cbeab7fa7 in reset_head /home/phil/src/git/reset.c:85
    #8 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
    #9 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
    #10 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
    #11 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
    #12 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
    #13 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
    #14 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-07 14:20:01 -07:00
Derrick Stolee
0299a69694 add: implement the --sparse option
We previously modified 'git add' to refuse updating index entries
outside of the sparse-checkout cone. This is justified to prevent users
from accidentally getting into a confusing state when Git removes those
files from the working tree at some later point.

Unfortunately, this caused some workflows that were previously possible
to become impossible, especially around merge conflicts outside of the
sparse-checkout cone. These were documented in tests within t1092.

We now re-enable these workflows using a new '--sparse' option to 'git
add'. This allows users to signal "Yes, I do know what I'm doing with
these files," and accept the consequences of the files leaving the
worktree later.

We delay updating the advice message until implementing a similar option
in 'git rm' and 'git mv'.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28 10:31:02 -07:00
Derrick Stolee
49fdd51a23 add: skip tracked paths outside sparse-checkout cone
When 'git add' adds a tracked file that is outside of the
sparse-checkout cone, it checks the SKIP_WORKTREE bit to see if the file
exists outside of the sparse-checkout cone. This is usually correct,
except in the case of a merge conflict outside of the cone.

Modify add_pathspec_matched_against_index() to be more careful about
paths by checking the sparse-checkout patterns in addition to the
SKIP_WORKTREE bit. This causes 'git add' to no longer allow files
outside of the cone that removed the SKIP_WORKTREE bit due to a merge
conflict.

With only this change, users will only be able to add the file after
adding the file to the sparse-checkout cone. A later change will allow
users to force adding even though the file is outside of the
sparse-checkout cone.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28 10:31:02 -07:00
Derrick Stolee
105e8b014b add: fail when adding an untracked sparse file
The add_files() method in builtin/add.c takes a set of untracked files
that are being added by the input pathspec and inserts them into the
index. If these files are outside of the sparse-checkout cone, then they
gain the SKIP_WORKTREE bit at some point. However, this was not checked
before inserting into the index, so these files are added even though we
want to avoid modifying the index outside of the sparse-checkout cone.

Add a check within add_files() for these files and write the advice
about files outside of the sparse-checkout cone.

This behavior change modifies some existing tests within t1092. These
tests intended to document how a user could interact with the existing
behavior in place. Many of these tests need to be marked as expecting
failure. A future change will allow these tests to pass by adding a flag
to 'git add' that allows users to modify index entries outside of the
sparse-checkout cone.

The 'submodule handling' test is intended to document what happens to
directories that contain a submodule when the sparse index is enabled.
It is not trying to say that users should be able to add submodules
outside of the sparse-checkout cone, so that test can be modified to
avoid that operation.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28 10:31:02 -07:00
Derrick Stolee
edd2cd345f t1092: behavior for adding sparse files
Add some tests to demonstrate the current behavior around adding files
outside of the sparse-checkout cone. Currently, untracked files are
handled differently from tracked files. A future change will make these
cases be handled the same way.

Further expand checking that a failed 'git add' does not stage changes
to the index.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28 10:31:02 -07:00
Derrick Stolee
516680ba77 sparse-index: integrate with cherry-pick and rebase
The hard work was already done with 'git merge' and the ORT strategy.
Just add extra tests to see that we get the expected results in the
non-conflict cases.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-09 15:49:05 -07:00
Derrick Stolee
c0b99303db t1092: add cherry-pick, rebase tests
Add tests to check that cherry-pick and rebase behave the same in the
sparse-index case as in the full index cases. These tests are agnostic
to GIT_TEST_MERGE_ALGORITHM, so a full CI test suite will check both the
'ort' and 'recursive' strategies on this test.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-09 15:49:04 -07:00
Derrick Stolee
6957636792 merge-ort: expand only for out-of-cone conflicts
Merge conflicts happen often enough to want to avoid expanding a sparse
index when they happen, as long as those conflicts are within the
sparse-checkout cone. If a conflict exists outside of the
sparse-checkout cone, then we still need to expand before iterating over
the index entries. This is critical to do in advance because of how the
original_cache_nr is tracked to allow inserting and replacing cache
entries.

Iterate over the conflicted files and check if any paths are outside of
the sparse-checkout cone. If so, then expand the full index.

Add a test that demonstrates that we do not expand the index, even when
we hit a conflict within the sparse-checkout cone.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-09 15:49:04 -07:00
Derrick Stolee
a33806398a merge: make sparse-aware with ORT
Allow 'git merge' to operate without expanding a sparse index, at least
not immediately. The index still will be expanded in a few cases:

1. If the merge strategy is 'recursive', then we enable
   command_requires_full_index at the start of the merge_recursive()
   method. We expect sparse-index users to also have the 'ort' strategy
   enabled.

2. With the 'ort' strategy, if the merge results in a conflicted file,
   then we expand the index before updating the working tree. The loop
   that iterates over the worktree replaces index entries and tracks
   'origintal_cache_nr' which can become completely wrong if the index
   expands in the middle of the operation. This safety valve is
   important before that loop starts. A later change will focus this
   to only expand if we indeed have a conflict outside of the
   sparse-checkout cone.

3. Other merge strategies are executed as a 'git merge-X' subcommand,
   and those strategies are currently protected with the
   'command_requires_full_index' guard.

Some test updates are required, including a mistaken 'git checkout -b'
that did not specify the base branch, causing merges to be fast-forward
merges.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-09 15:49:04 -07:00
Derrick Stolee
939fa07582 add: ignore outside the sparse-checkout in refresh()
Since b243012 (refresh_index(): add flag to ignore SKIP_WORKTREE
entries, 2021-04-08), 'git add --refresh <path>' will output a warning
message when the path is outside the sparse-checkout definition. The
implementation of this warning happened in parallel with the
sparse-index work to add ensure_full_index() calls throughout the
codebase.

Update this loop to have the proper logic that checks to see if the
pathspec is outside the sparse-checkout definition. This avoids the need
to expand the sparse directory entry and determine if the path is
tracked, untracked, or ignored. We simply avoid updating the stat()
information because there isn't even an entry that matches the path!

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-29 12:36:34 -07:00
Derrick Stolee
4eaffd81a5 pathspec: stop calling ensure_full_index
The add_pathspec_matches_against_index() focuses on matching a pathspec
to file entries in the index. This already works correctly for its only
use: checking if untracked files exist in the index.

The compatibility checks in t1092 already test that 'git add <dir>'
works for a directory outside of the sparse cone. That provides coverage
for removing this guard.

This finalizes our ability to run 'git add .' without expanding a sparse
index to a full one. This is evidenced by an update to t1092 and by
these performance numbers for p2000-sparse-operations.sh:

Test                                    HEAD~1            HEAD
--------------------------------------------------------------------------------
2000.10: git add . (full-index-v3)      0.37(0.28+0.07)   0.36(0.27+0.06) -2.7%
2000.11: git add . (full-index-v4)      0.33(0.26+0.06)   0.32(0.28+0.05) -3.0%
2000.12: git add . (sparse-index-v3)    0.57(0.53+0.07)   0.06(0.06+0.07) -89.5%
2000.13: git add . (sparse-index-v4)    0.57(0.53+0.07)   0.05(0.03+0.09) -91.2%

While the ~90% improvement is shown by the test results, it is worth
noting that expanding the sparse index was adding overhead in previous
commits. Comparing to the full index case, we see the performance go
from 0.33s to 0.05s, an 85% improvement.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-29 12:36:34 -07:00
Derrick Stolee
5e7cbab196 add: allow operating on a sparse-only index
Disable command_requires_full_index for 'git add'. This does not require
any additional removals of ensure_full_index(). The main reason is that
'git add' discovers changes based on the pathspec and the worktree
itself. These are then inserted into the index directly, and calls to
index_name_pos() or index_file_exists() already call expand_to_path() at
the appropriate time to support a sparse-index.

Add a test to check that 'git add -A' and 'git add <file>' does not
expand the index at all, as long as <file> is not within a sparse
directory. This does not help the global 'git add .' case.

We can measure the improvement using p2000-sparse-operations.sh with
these results:

Test                                  HEAD~1           HEAD
------------------------------------------------------------------------------
2000.6: git add -A (full-index-v3)    0.35(0.30+0.05)  0.37(0.29+0.06) +5.7%
2000.7: git add -A (full-index-v4)    0.31(0.26+0.06)  0.33(0.27+0.06) +6.5%
2000.8: git add -A (sparse-index-v3)  0.57(0.53+0.07)  0.05(0.04+0.08) -91.2%
2000.9: git add -A (sparse-index-v4)  0.58(0.55+0.06)  0.05(0.05+0.06) -91.4%

While the 91% improvement seems impressive, it's important to recognize
that previously we had significant overhead for expanding the
sparse-index. Comparing to the full index case, 'git add -A' goes from
0.37s to 0.05s, which is "only" an 86% improvement.

This modification to 'git add' creates some behavior change depending on
the use of a sparse index. We modify a test in t1092 to demonstrate
these changes which will be remedied in future changes.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-29 12:36:34 -07:00
Derrick Stolee
83ad8ca596 t1092: test merge conflicts outside cone
Conflicts can occur outside of the sparse-checkout definition, and in
that case users might try to resolve the conflicts in several ways.
Document a few of these ways in a test. Make it clear that this behavior
is not necessarily the optimal flow, since users can become confused
when Git deletes these files from the worktree in later commands.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-29 12:36:34 -07:00
Derrick Stolee
e05cdb17e8 unpack-trees: resolve sparse-directory/file conflicts
When running unpack_trees() with a sparse index, we attempt to operate
on the index without expanding the sparse directory entries. Thus, we
operate by manipulating entire directories and passing them to the
unpack function. In the case of the 'git checkout' command, this is the
twoway_merge() function.

There are several cases in twoway_merge() that handle different
situations. One new one to add is the case of a directory/file conflict
where the directory is sparse. Before the sparse index, such a conflict
would appear as a list of file additions and deletions. Now,
twoway_merge() initializes 'current', 'oldtree', and 'newtree' from
src[0], src[1], and src[2], then sets 'oldtree' to NULL because it is
equal to the df_conflict_entry. The way to determine that we have a
directory/file conflict is to test that 'current' and 'newtree' disagree
on being sparse directory entries.

When we are in this case, we want to resolve the situation by calling
merged_entry(). This allows replacing the 'current' entry with the
'newtree' entry. This is important for cases where we want to run 'git
checkout' across the conflict and have the new HEAD represent the new
file type at that path. The first NEEDSWORK comment dropped in t1092
demonstrates this necessary behavior.

However, we still are in a confusing state when 'current' corresponds to
a staged change within a sparse directory that is not present at HEAD.
This should be atypical, because it requires adding a change outside of
the sparse-checkout cone, but it is possible. Since we are unable to
determine that this is a staged change within twoway_merge(), we cannot
add a case to reject the merge at this point. I believe this is due to
the use of df_conflict_entry in the place of 'oldtree' instead of using
the valud at HEAD, which would provide some perspective to this
decision. Any change that would allow this differentiation for staged
entries would need to involve information further up in unpack_trees().

That work should be done, sometime, because we are further confusing the
behavior of a directory/file conflict when staging a change in the
directory. The two cases 'checkout behaves oddly with df-conflict-?' in
t1092 demonstrate that even without a sparse-checkout, Git is not
consistent in its behavior. Neither of the two options seems correct,
either. This change makes the sparse-index behave differently than the
typcial sparse-checkout case, but it does match the full checkout
behavior in the df-conflict-2 case.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-20 14:59:11 -07:00
Derrick Stolee
70569fadce t1092: document bad 'git checkout' behavior
Add new branches to the test repo that demonstrate directory/file
conflicts in different ways. Since the directory 'folder1/' has
adjacent files 'folder1-', 'folder1.txt', and 'folder10' it causes
searches for 'folder1/' to land in a different place in the index than a
search for 'folder1'. This causes a change in behavior when working with
the df-conflict-1 and df-conflict-2 branches, whose only difference is
that the first uses 'folder1' as the conflict and the other uses
'folder2' which does not have these adjacent files.

We can extend two tests that compare the behavior across different 'git
checkout' commands, and we see already that the behavior will be
different in some cases and not in others. The difference between the
two test loops is that one uses 'git reset --hard' between iterations.

Further, we isolate the behavior of creating a staged change within a
directory and then checking out a branch where that directory is
replaced with a file. A full checkout behaves differently across these
two cases, while a sparse-checkout cone behaves consistently. In both
cases, the behavior is wrong. In one case, the staged change is dropped
entirely. The other case the staged change is kept, replacing the file
at that location, but none of the other files in the directory are kept.

Likely, the correct behavior in this case is to reject the checkout and
report the conflict, leaving HEAD in its previous location. None of the
cases behave this way currently. Use comments to demonstrate that the
tested behavior is only a documentation of the current, incorrect
behavior to ensure we do not _accidentally_ change it. Instead, we would
prefer to change it on purpose with a future change.

At this point, the sparse-index does not handle these 'git checkout'
commands correctly. Or rather, it _does_ reject the 'git checkout' when
we have the staged change, but for the wrong reason. It also rejects the
'git checkout' commands when there is no staged change and we want to
replace a directory with a file. A fix for that unstaged case will
follow in the next change, but that will make the sparse-index agree
with the full checkout case in these documented incorrect behaviors.

Helped-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-20 14:59:11 -07:00
Derrick Stolee
1ba5f45132 checkout: stop expanding sparse indexes
Previous changes did the necessary improvements to unpack-trees.c and
diff-lib.c in order to modify a sparse index based on its comparision
with a tree. The only remaining work is to remove some
ensure_full_index() calls and add tests that verify that the index is
not expanded in our interesting cases. Include 'switch' and 'restore' in
these tests, as they share a base implementation with 'checkout'.

Here are the relevant performance results from
p2000-sparse-operations.sh:

Test                                     HEAD~1           HEAD
--------------------------------------------------------------------------------
2000.18: git checkout -f - (full-v3)     0.49(0.43+0.03)  0.47(0.39+0.05) -4.1%
2000.19: git checkout -f - (full-v4)     0.45(0.37+0.06)  0.42(0.37+0.05) -6.7%
2000.20: git checkout -f - (sparse-v3)   0.76(0.71+0.07)  0.04(0.03+0.04) -94.7%
2000.21: git checkout -f - (sparse-v4)   0.75(0.72+0.04)  0.05(0.06+0.04) -93.3%

It is important to compare the full index case to the sparse index case,
as the previous results for the sparse index were inflated by the index
expansion. For index v4, this is an 88% improvement.

On an internal repository with over two million paths at HEAD and a
sparse-checkout definition containing ~60,000 of those paths, 'git
checkout' went from 3.5s to 297ms with this change. The theoretical
optimum where only those ~60,000 paths exist was 275ms, so the extra
sparse directory entries contribute a 22ms overhead.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-14 15:05:53 -07:00
Derrick Stolee
daa1acefc5 commit: integrate with sparse-index
Update 'git commit' to allow using the sparse-index in memory without
expanding to a full one. The only place that had an ensure_full_index()
call was in cache_tree_update(). The recursive algorithm for
update_one() was already updated in 2de37c536 (cache-tree: integrate
with sparse directory entries, 2021-03-03) to handle sparse directory
entries in the index.

Most of this change involves testing different command-line options that
allow specifying which on-disk changes should be included in the commit.
This includes no options (only take currently-staged changes), -a (take
all tracked changes), and --include (take a list of specific changes).
To simplify testing that these options do not expand the index, update
the test that previously verified that 'git status' does not expand the
index with a helper method, ensure_not_expanded().

This allows 'git commit' to operate much faster when the sparse-checkout
cone is much smaller than the full list of files at HEAD.

Here are the relevant lines from p2000-sparse-operations.sh:

Test                                      HEAD~1           HEAD
----------------------------------------------------------------------------------
2000.14: git commit -a -m A (full-v3)     0.35(0.26+0.06)  0.36(0.28+0.07) +2.9%
2000.15: git commit -a -m A (full-v4)     0.32(0.26+0.05)  0.34(0.28+0.06) +6.3%
2000.16: git commit -a -m A (sparse-v3)   0.63(0.59+0.06)  0.04(0.05+0.05) -93.7%
2000.17: git commit -a -m A (sparse-v4)   0.64(0.59+0.08)  0.04(0.04+0.04) -93.8%

It is important to compare the full-index case to the sparse-index case,
so the improvement for index version v4 is actually an 88% improvement in
this synthetic example.

In a real repository with over two million files at HEAD and 60,000
files in the sparse-checkout definition, the time for 'git commit -a'
went from 2.61 seconds to 134ms. I compared this to the result if the
index only contained the paths in the sparse-checkout definition and
found the theoretical optimum to be 120ms, so the out-of-cone paths only
add a 12% overhead.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-14 15:05:53 -07:00
Derrick Stolee
e5ca291076 t1092: document bad sparse-checkout behavior
There are several situations where a repository with sparse-checkout
enabled will act differently than a normal repository, and in ways that
are not intentional. The test t1092-sparse-checkout-compatibility.sh
documents some of these deviations, but a casual reader might think
these are intentional behavior changes.

Add comments on these tests that make it clear that these behaviors
should be updated. Using 'NEEDSWORK' helps contributors find that these
are potential areas for improvement.

Helped-by: Elijah Newren <newren@gmail.com>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-14 13:42:49 -07:00
Derrick Stolee
fe0d576153 wt-status: expand added sparse directory entries
It is difficult, but possible, to get into a state where we intend to
add a directory that is outside of the sparse-checkout definition. Add a
test to t1092-sparse-checkout-compatibility.sh that demonstrates this
using a combination of 'git reset --mixed' and 'git checkout --orphan'.

This test failed before because the output of 'git status
--porcelain=v2' would not match on the lines for folder1/:

* The sparse-checkout repo (with a full index) would output each path
  name that is intended to be added.

* The sparse-index repo would only output that "folder1/" is staged for
  addition.

The status should report the full list of files to be added, and so this
sparse-directory entry should be expanded to a full list when reaching
it inside the wt_status_collect_changes_initial() method. Use
read_tree_at() to assist.

Somehow, this loop over the cache entries was not guarded by
ensure_full_index() as intended.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-14 13:42:49 -07:00
Derrick Stolee
d76723ee53 status: use sparse-index throughout
By testing 'git -c core.fsmonitor= status -uno', we can check for the
simplest index operations that can be made sparse-aware. The necessary
implementation details are already integrated with sparse-checkout, so
modify command_requires_full_index to be zero for cmd_status().

In refresh_index(), we loop through the index entries to refresh their
stat() information. However, sparse directories have no stat()
information to populate. Ignore these entries.

This allows 'git status' to no longer expand a sparse index to a full
one. This is further tested by dropping the "-uno" option and adding an
untracked file into the worktree.

The performance test p2000-sparse-checkout-operations.sh demonstrates
these improvements:

Test                                  HEAD~1           HEAD
-----------------------------------------------------------------------------
2000.2: git status (full-index-v3)    0.31(0.30+0.05)  0.31(0.29+0.06) +0.0%
2000.3: git status (full-index-v4)    0.31(0.29+0.07)  0.34(0.30+0.08) +9.7%
2000.4: git status (sparse-index-v3)  2.35(2.28+0.10)  0.04(0.04+0.05) -98.3%
2000.5: git status (sparse-index-v4)  2.35(2.24+0.15)  0.05(0.04+0.06) -97.9%

Note that since HEAD~1 was expanding the sparse index by parsing trees,
it was artificially slower than the full index case. Thus, the 98%
improvement is misleading, and instead we should celebrate the 0.34s to
0.05s improvement of 85%. This is more indicative of the peformance
gains we are expecting by using a sparse index.

Note: we are dropping the assignment of core.fsmonitor here. This is not
necessary for the test script as we are not altering the config any
other way. Correct integration with FS Monitor will be validated in
later changes.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-14 13:42:49 -07:00
Derrick Stolee
bf48e5acdb status: skip sparse-checkout percentage with sparse-index
'git status' began reporting a percentage of populated paths when
sparse-checkout is enabled in 051df3cf (wt-status: show sparse
checkout status as well, 2020-07-18). This percentage is incorrect when
the index has sparse directories. It would also be expensive to
calculate as we would need to parse trees to count the total number of
possible paths.

Avoid the expensive computation by simplifying the output to only report
that a sparse checkout exists, without the percentage.

This change is the reason we use 'git status --porcelain=v2' in
t1092-sparse-checkout-compatibility.sh. We don't want to ensure that
this message is equal across both modes, but instead just the important
information about staged, modified, and untracked files are compared.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-14 13:42:49 -07:00
Derrick Stolee
bf26c06f12 t1092: add tests for status/add and sparse files
Before moving to update 'git status' and 'git add' to work with sparse
indexes, add an explicit test that ensures the sparse-index works the
same as a normal sparse-checkout when the worktree contains directories
and files outside of the sparse cone.

Specifically, 'folder1/a' is a file in our test repo, but 'folder1' is
not in the sparse cone. When 'folder1/a' is modified, the file is not
shown as modified and adding it will fail. This is new behavior as of
a20f704 (add: warn when asked to update SKIP_WORKTREE entries,
2021-04-08). Before that change, these adds would be silently ignored.

Untracked files are fine: adding new files both with 'git add .' and
'git add folder1/' works just as in a full checkout. This may not be
entirely desirable, but we are not intending to change behavior at the
moment, only document it. A future change could alter the behavior to
be more sensible, and this test could be modified to satisfy the new
expected behavior.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-14 13:42:48 -07:00
Derrick Stolee
e669ffb2b8 t1092: expand repository data shape
As more features integrate with the sparse-index feature, more and more
special cases arise that require different data shapes within the tree
structure of the repository in order to demonstrate those cases.

Add several interesting special cases all at once instead of sprinkling
them across several commits. The interesting cases being added here are:

* Add sparse-directory entries on both sides of directories within the
  sparse-checkout definition.

* Add directories outside the sparse-checkout definition who have only
  one entry and are the first entry of a directory with multiple
  entries.

* Add filenames adjacent to a sparse directory entry that sort before
  and after the trailing slash.

Later tests will take advantage of these shapes, but they also deepen
the tests that already exist.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-14 13:42:48 -07:00
Derrick Stolee
3d814b5dc0 t1092: replace incorrect 'echo' with 'cat'
This fixes the test data shape to be as expected, allowing rename
detection to work properly now that the 'larger-content' file actually
has meaningful lines.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-14 13:42:21 -07:00
Derrick Stolee
fc6609d198 sparse-index: skip indexes with unmerged entries
The sparse-index format is designed to be compatible with merge
conflicts, even those outside the sparse-checkout definition. The reason
is that when converting a full index to a sparse one, a cache entry with
nonzero stage will not be collapsed into a sparse directory entry.

However, this behavior was not tested, and a different behavior within
convert_to_sparse() fails in this scenario. Specifically,
cache_tree_update() will fail when unmerged entries exist.
convert_to_sparse_rec() uses the cache-tree data to recursively walk the
tree structure, but also to compute the OIDs used in the
sparse-directory entries.

Add an index scan to convert_to_sparse() that will detect if these merge
conflict entries exist and skip the conversion before trying to update
the cache-tree. This is marked as NEEDSWORK because this can be removed
with a suitable update to cache_tree_update() or a similar method that
can construct a cache-tree with invalid nodes, but still allow creating
the nodes necessary for creating sparse directory entries.

It is possible that in the future we will not need to make such an
update, since if we do not expand a sparse-index into a full one, this
conversion does not need to happen. Thus, this can be deferred until the
merge machinery is made to integrate with the sparse-index.

Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-07-14 13:42:21 -07:00
Junio C Hamano
a96355d84c t1092: revert the "-1" hack for emulating "no progress meter"
This looked like a good idea, but it seems to break tests on 32-bit
builds rather badly.  Revert to just use "100 thousands must be big
enough" for now.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-05-26 06:23:58 +09:00
Derrick Stolee
e2b05746e1 t1092: use GIT_PROGRESS_DELAY for consistent results
The t1092-sparse-checkout-compatibility.sh tests compare the stdout and
stderr for several Git commands across both full checkouts, sparse
checkouts with a full index, and sparse checkouts with a sparse index.
Since these are direct comparisons, sometimes a progress indicator can
flush at unpredictable points, especially on slower machines. This
causes the tests to be flaky.

One standard way to avoid this is to add GIT_PROGRESS_DELAY=0 to the Git
commands that are run, as this will force every progress indicator
created with start_progress_delay() to be created immediately. However,
there are some progress indicators that are created in the case of a
full index that are not created with a sparse index. Moreover, their
values may be different as those indexes have a different number of
entries.

Instead, use GIT_PROGRESS_DELAY=-1 (which will turn into UINT_MAX)
to ensure that any reasonable machine running these tests would
never display delayed progress indicators.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-05-25 15:30:33 +09:00
Derrick Stolee
9ad2d5ea71 sparse-index: loose integration with cache_tree_verify()
The cache_tree_verify() method is run when GIT_TEST_CHECK_CACHE_TREE
is enabled, which it is by default in the test suite. The logic must
be adjusted for the presence of these directory entries.

For now, leave the test as a simple check for whether the directory
entry is sparse. Do not go any further until needed.

This allows us to re-enable GIT_TEST_CHECK_CACHE_TREE in
t1092-sparse-checkout-compatibility.sh. Further,
p2000-sparse-operations.sh uses the test suite and hence this is enabled
for all tests. We need to integrate with it before we run our
performance tests with a sparse-index.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30 12:57:48 -07:00
Derrick Stolee
122ba1f7b5 sparse-checkout: toggle sparse index from builtin
The sparse index extension is used to signal that index writes should be
in sparse mode. This was only updated using GIT_TEST_SPARSE_INDEX=1.

Add a '--[no-]sparse-index' option to 'git sparse-checkout init' that
specifies if the sparse index should be used. It also updates the index
to use the correct format, either way. Add a warning in the
documentation that the use of a repository extension might reduce
compatibility with third-party tools. 'git sparse-checkout init' already
sets extension.worktreeConfig, which places most sparse-checkout users
outside of the scope of most third-party tools.

Update t1092-sparse-checkout-compatibility.sh to use this CLI instead of
GIT_TEST_SPARSE_INDEX=1.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30 12:57:48 -07:00
Derrick Stolee
0938e6ff55 sparse-index: check index conversion happens
Add a test case that uses test_region to ensure that we are truly
expanding a sparse index to a full one, then converting back to sparse
when writing the index. As we integrate more Git commands with the
sparse index, we will convert these commands to check that we do _not_
convert the sparse index to a full index and instead stay sparse the
entire time.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30 12:57:47 -07:00
Derrick Stolee
f442313e2e submodule: sparse-index should not collapse links
A submodule is stored as a "Git link" that actually points to a commit
within a submodule. Submodules are populated or not depending on
submodule configuration, not sparse-checkout. To ensure that the
sparse-index feature integrates correctly with submodules, we should not
collapse a directory if there is a Git link within its range.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30 12:57:47 -07:00
Derrick Stolee
6e773527b6 sparse-index: convert from full to sparse
If we have a full index, then we can convert it to a sparse index by
replacing directories outside of the sparse cone with sparse directory
entries. The convert_to_sparse() method does this, when the situation is
appropriate.

For now, we avoid converting the index to a sparse index if:

 1. the index is split.
 2. the index is already sparse.
 3. sparse-checkout is disabled.
 4. sparse-checkout does not use cone mode.

Finally, we currently limit the conversion to when the
GIT_TEST_SPARSE_INDEX environment variable is enabled. A mode using Git
config will be added in a later change.

The trickiest thing about this conversion is that we might not be able
to mark a directory as a sparse directory just because it is outside the
sparse cone. There might be unmerged files within that directory, so we
need to look for those. Also, if there is some strange reason why a file
is not marked with CE_SKIP_WORKTREE, then we should give up on
converting that directory. There is still hope that some of its
subdirectories might be able to convert to sparse, so we keep looking
deeper.

The conversion process is assisted by the cache-tree extension. This is
calculated from the full index if it does not already exist. We then
abandon the cache-tree as it no longer applies to the newly-sparse
index. Thus, this cache-tree will be recalculated in every
sparse-full-sparse round-trip until we integrate the cache-tree
extension with the sparse index.

Some Git commands use the index after writing it. For example, 'git add'
will update the index, then write it to disk, then read its entries to
report information. To keep the in-memory index in a full state after
writing, we re-expand it to a full one after the write. This is wasteful
for commands that only write the index and do not read from it again,
but that is only the case until we make those commands "sparse aware."

We can compare the behavior of the sparse-index in
t1092-sparse-checkout-compability.sh by using GIT_TEST_SPARSE_INDEX=1
when operating on the 'sparse-index' repo. We can also compare the two
sparse repos directly, such as comparing their indexes (when expanded to
full in the case of the 'sparse-index' repo). We also verify that the
index is actually populated with sparse directory entries.

The 'checkout and reset (mixed)' test is marked for failure when
comparing a sparse repo to a full repo, but we can compare the two
sparse-checkout cases directly to ensure that we are not changing the
behavior when using a sparse index.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30 12:57:47 -07:00
Derrick Stolee
2782db3eed test-tool: don't force full index
We will use 'test-tool read-cache --table' to check that a sparse
index is written as part of init_repos. Since we will no longer always
expand a sparse index into a full index, add an '--expand' parameter
that adds a call to ensure_full_index() so we can compare a sparse index
directly against a full index, or at least what the in-memory index
looks like when expanded in this way.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30 12:57:46 -07:00
Derrick Stolee
ecfc47c066 t1092: compare sparse-checkout to sparse-index
Add a new 'sparse-index' repo alongside the 'full-checkout' and
'sparse-checkout' repos in t1092-sparse-checkout-compatibility.sh. Also
add run_on_sparse and test_sparse_match helpers. These helpers will be
used when the sparse index is implemented.

Add the GIT_TEST_SPARSE_INDEX environment variable to enable the
sparse-index by default. This can be enabled across all tests, but that
will only affect cases where the sparse-checkout feature is enabled.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30 12:57:45 -07:00
Derrick Stolee
4b3f765a2f t1092: clean up script quoting
This test was introduced in 19a0acc83e (t1092: test interesting
sparse-checkout scenarios, 2021-01-23), but it contains issues with quoting
that were not noticed until starting this follow-up series. The old
mechanism would drop quoting such as in

   test_all_match git commit -m "touch README.md"

The above happened to work because README.md is a file in the
repository, so 'git commit -m touch REAMDE.md' would succeed by
accident.

Other cases included quoting for no good reason, so clean that up now.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-30 12:57:45 -07:00
Derrick Stolee
19a0acc83e t1092: test interesting sparse-checkout scenarios
These also document some behaviors that differ from a full checkout, and
possibly in a way that is not intended.

The test is designed to be run with "--run=1,X" where 'X' is an
interesting test case. Each test uses 'init_repos' to reset the full and
sparse copies of the initial-repo that is created by the first test
case. This also makes it possible to have test cases leave the working
directory or index in unusual states without disturbing later cases.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-01-23 17:14:20 -08:00