[PATCH v4 0/3] grep: integrate with sparse index
- From
Shaoxuan Yuan <shaoxuan.yuan02@gmail.com>
- Date
- Sep 3, 2022, 00:36 UTC
- Message-ID
- <20220903003623.64750-1-shaoxuan.yuan02@gmail.com>
- In-Reply-To
- <20220817075633.217934-1-shaoxuan.yuan02@gmail.com>
Integrate `git-grep` with sparse-index and test the performance improvement.
Changes since v3 ---------------- * Shorten the perf result tables in commit message.
* Update the commit message to reflect the changes in the commit.
* Update the commit message to indicate the performance improvement is dependent on the pathspec.
* Stop passing `ce_mode` through `check_attr`. Instead, set the `base_len` to 0 to make the code more reasonable and less abuse of `check_attr`.
* Remove another invention of `base`. Use the existing `name` as the argument for `grep_tree()`, and reset it back to `ce->name` after `grep_tree()` returns.
* Update the p2000 test to use a more general pathspec for better compatibility (i.e. do not use git repository specific pathspec).
* Add tests to t1092 'grep is not expanded' to verify the change brought by "builtin/grep.c: walking tree instead of expanding index with --sparse": the index *never* expands.
Changes since v2 ----------------
* Modify the commit message for "builtin/grep.c: integrate with sparse index" to make it obvious that the perf test results are not from p2000 tests, but from manual perf runs.
* Add tree-walking logic as an extra (the third) patch to improve the performance when --sparse is used. This resolved the left-over-bit in v2 [1].
[1] https://lore.kernel.org/git/20220829232843.183711-1-shaoxuan.yuan02@gmail.com/
Changes since v1 ----------------
* Rewrite the commit message for "builtin/grep.c: add --sparse option" to be clearer.
* Update the documentation (both in-code and man page) for --sparse.
* Add a few tests to test the new behavior (when _only_ --cached is supplied).
* Reformat the perf test results to not look like directly from p2000 tests.
* Put the "command_requires_full_index" lines right after parse_options().
* Add a pathspec test in t1092, and reword a few test documentations.
Shaoxuan Yuan (3): builtin/grep.c: add --sparse option builtin/grep.c: integrate with sparse index builtin/grep.c: walking tree instead of expanding index with --sparse
Documentation/git-grep.txt | 5 +++- builtin/grep.c | 31 ++++++++++++++++++--- t/perf/p2000-sparse-operations.sh | 1 + t/t1092-sparse-checkout-compatibility.sh | 26 ++++++++++++++++++ t/t7817-grep-sparse-checkout.sh | 34 +++++++++++++++++++----- 5 files changed, 86 insertions(+), 11 deletions(-)
Range-diff against v3:
1: 1fa8c62d95 ! 1: f1d8271a9b builtin/grep.c: add --sparse option
@@ Commit message
inspects paths outside of the sparse-checkout definition when paired
with the '--cached' option.
- Helped-by: Derrick Stolee <derrickstolee@github.com>
Suggested-by: Victoria Dye <vdye@github.com>
+ Helped-by: Derrick Stolee <derrickstolee@github.com>
+ Helped-by: Victoria Dye <vdye@github.com>
Signed-off-by: Shaoxuan Yuan <shaoxuan.yuan02@gmail.com>
## Documentation/git-grep.txt ##
2: ce4fba3c35 ! 2: 7aa4b8bc81 builtin/grep.c: integrate with sparse index
@@ Commit message
are then extracted from the time difference between "region_enter" and
"region_leave" of label "do_read_index".
+ Helped-by: Victoria Dye <vdye@github.com>
Helped-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Shaoxuan Yuan <shaoxuan.yuan02@gmail.com>
3: 240883aa11 ! 3: 6a2e753a19 builtin/grep.c: walking tree instead of expanding index with --sparse
@@ Commit message
- Summary:
- p2000 tests demonstrate a ~91% execution time reduction for
- `git grep --cached --sparse <pattern> -- <pathspec>` using tree-walking
- logic.
-
- Test HEAD~ HEAD
- ---------------------------------------------------------------------------------------------------
- 2000.78: git grep --cached --sparse bogus -- f2/f1/f1/builtin/* (full-v3) 0.11 0.09 (≈)
- 2000.79: git grep --cached --sparse bogus -- f2/f1/f1/builtin/* (full-v4) 0.08 0.09 (≈)
- 2000.80: git grep --cached --sparse bogus -- f2/f1/f1/builtin/* (sparse-v3) 0.44 0.04 (-90.9%)
- 2000.81: git grep --cached --sparse bogus -- f2/f1/f1/builtin/* (sparse-v4) 0.46 0.04 (-91.3%)
+ p2000 tests demonstrate a ~71% execution time reduction for
+ `git grep --cached --sparse bogus -- "f2/f1/f1/*"` using tree-walking
+ logic. However, notice that this result varies depending on the pathspec
+ given. See below "Command used for testing" for more details.
+
+ Test HEAD~ HEAD
+ -------------------------------------------------------
+ 2000.78: git grep ... (full-v3) 0.35 0.39 (≈)
+ 2000.79: git grep ... (full-v4) 0.36 0.30 (≈)
+ 2000.80: git grep ... (sparse-v3) 0.88 0.23 (-73.8%)
+ 2000.81: git grep ... (sparse-v4) 0.83 0.26 (-68.6%)
- Command used for testing:
- git grep --cached --sparse bogus -- f2/f1/f1/builtin/*
+ git grep --cached --sparse bogus -- "f2/f1/f1/*"
The reason for specifying a pathspec is that, if we don't specify a
pathspec, then grep_tree() will walk all the trees and blobs to find the
@@ Commit message
logic will only walk the area of trees enclosed by the pathspec, and the
time consumed is reasonably a lot less.
+ Generally speaking, because the performance gain is acheived by walking
+ less trees, which are specified by the pathspec, the HEAD time v.s.
+ HEAD~ time in sparse-v[3|4], should be proportional to
+ "pathspec enclosed area" v.s. "all area", respectively. Namely, the
+ wider the <pathspec> is encompassing, the less the performance
+ difference between HEAD~ and HEAD, and vice versa.
+
That is, if we don't specify a pathspec, the performance difference [1]
- is quite small: both methods walk all the trees and take generally same
- amount of time (even with the index construction time included for
+ is indistinguishable: both methods walk all the trees and take generally
+ same amount of time (even with the index construction time included for
ensure_full_index()).
- [1] Performance test result without pathspec:
+ [1] Performance test result without pathspec (hence walking all trees):
+
+ Command used:
+
+ git grep --cached --sparse bogus
- Test HEAD~ HEAD
- -----------------------------------------------------------------------------
- 2000.78: git grep --cached --sparse bogus (full-v3) 6.17 5.19 (≈)
- 2000.79: git grep --cached --sparse bogus (full-v4) 6.19 5.46 (≈)
- 2000.80: git grep --cached --sparse bogus (sparse-v3) 6.57 6.44 (≈)
- 2000.81: git grep --cached --sparse bogus (sparse-v4) 6.65 6.28 (≈)
+ Test HEAD~ HEAD
+ ---------------------------------------------------
+ 2000.78: git grep ... (full-v3) 6.17 5.19 (≈)
+ 2000.79: git grep ... (full-v4) 6.19 5.46 (≈)
+ 2000.80: git grep ... (sparse-v3) 6.57 6.44 (≈)
+ 2000.81: git grep ... (sparse-v4) 6.65 6.28 (≈)
Suggested-by: Derrick Stolee <derrickstolee@github.com>
Helped-by: Derrick Stolee <derrickstolee@github.com>
@@ builtin/grep.c: static int grep_cache(struct grep_opt *opt,
+ struct tree_desc tree;
+ void *data;
+ unsigned long size;
-+ struct strbuf base = STRBUF_INIT;
-+
-+ strbuf_addstr(&base, ce->name);
+
+ data = read_object_file(&ce->oid, &type, &size);
+ init_tree_desc(&tree, data, size);
- if (S_ISREG(ce->ce_mode) &&
-+ /*
-+ * sneak in the ce_mode using check_attr parameter
-+ */
-+ hit |= grep_tree(opt, pathspec, &tree, &base,
-+ base.len, ce->ce_mode);
-+ strbuf_release(&base);
++ hit |= grep_tree(opt, pathspec, &tree, &name, 0, 0);
++ strbuf_reset(&name);
++ strbuf_addstr(&name, ce->name);
+ free(data);
+ } else if (S_ISREG(ce->ce_mode) &&
match_pathspec(repo->index, pathspec, name.buf, name.len, 0, NULL,
S_ISDIR(ce->ce_mode) ||
S_ISGITLINK(ce->ce_mode))) {
-@@ builtin/grep.c: static int grep_tree(struct grep_opt *opt, const struct pathspec *pathspec,
- int te_len = tree_entry_len(&entry);
-
- if (match != all_entries_interesting) {
-- strbuf_addstr(&name, base->buf + tn_len);
-+ if (S_ISSPARSEDIR(check_attr)) {
-+ // object is a sparse directory entry
-+ strbuf_addbuf(&name, base);
-+ } else {
-+ // object is a commit or a root tree
-+ strbuf_addstr(&name, base->buf + tn_len);
-+ }
-+
- match = tree_entry_interesting(repo->index,
- &entry, &name,
- 0, pathspec);
## t/perf/p2000-sparse-operations.sh ##
@@ t/perf/p2000-sparse-operations.sh: test_perf_on_all git read-tree -mu HEAD
test_perf_on_all git checkout-index -f --all
test_perf_on_all git update-index --add --remove $SPARSE_CONE/a
test_perf_on_all "git rm -f $SPARSE_CONE/a && git checkout HEAD -- $SPARSE_CONE/a"
-+test_perf_on_all git grep --cached --sparse bogus -- "f2/f1/f1/builtin/*"
++test_perf_on_all git grep --cached --sparse bogus -- "f2/f1/f1/*"
+
+ test_done
+
+ ## t/t1092-sparse-checkout-compatibility.sh ##
+@@ t/t1092-sparse-checkout-compatibility.sh: test_expect_success 'grep is not expanded' '
+
+ # All files within the folder1/* pathspec are sparse,
+ # so this command does not find any matches
+- ensure_not_expanded ! grep a -- folder1/*
++ ensure_not_expanded ! grep a -- folder1/* &&
++
++ # test out-of-cone pathspec with or without wildcard
++ ensure_not_expanded grep --sparse --cached a -- "folder1/a" &&
++ ensure_not_expanded grep --sparse --cached a -- "folder1/*" &&
++
++ # test in-cone pathspec with or without wildcard
++ ensure_not_expanded grep --sparse --cached a -- "deep/a" &&
++ ensure_not_expanded grep --sparse --cached a -- "deep/*"
+ '
test_donebase-commit: be1a02a17ede4082a86dfbfee0f54f345e8b43ac
-- 2.37.0