[v3,09/10] revision: empty pathspecs should not use Bloom filters
diff mbox series

Message ID 7d6163305aa6ba295d5bc5ee685b158ae2853d93.1593174637.git.gitgitgadget@gmail.com
State New
Headers show
Series
  • More commit-graph/Bloom filter improvements
Related show

Commit Message

Elijah Newren via GitGitGadget June 26, 2020, 12:30 p.m. UTC
From: Taylor Blau <me@ttaylorr.com>

The prepare_to_use_bloom_filter() method was not intended to be called
on an empty pathspec. However, 'git log -- .' and 'git log' are subtly
different: the latter reports all commits while the former will simplify
commits that do not change the root tree.

This means that the path used to construct the bloom_key might be empty,
and that value is not added to the Bloom filter during construction.
That means that the results are likely incorrect!

To resolve the issue, be careful about the length of the path and stop
filling Bloom filters. To be completely sure we do not use them, drop
the pointer to the bloom_filter_settings from the commit-graph. That
allows our test to look at the trace2 logs to verify no Bloom filter
statistics are reported.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 revision.c           | 4 ++++
 t/t4216-log-bloom.sh | 4 ++++
 2 files changed, 8 insertions(+)

Patch
diff mbox series

diff --git a/revision.c b/revision.c
index ed59084f50..b53377cd52 100644
--- a/revision.c
+++ b/revision.c
@@ -704,6 +704,10 @@  static void prepare_to_use_bloom_filter(struct rev_info *revs)
 		path = pi->match;
 
 	len = strlen(path);
+	if (!len) {
+		revs->bloom_filter_settings = NULL;
+		return;
+	}
 
 	revs->bloom_key = xmalloc(sizeof(struct bloom_key));
 	fill_bloom_key(path, len, revs->bloom_key, revs->bloom_filter_settings);
diff --git a/t/t4216-log-bloom.sh b/t/t4216-log-bloom.sh
index 73ed51b595..e3e4badd4c 100755
--- a/t/t4216-log-bloom.sh
+++ b/t/t4216-log-bloom.sh
@@ -112,6 +112,10 @@  test_expect_success 'git log -- multiple path specs does not use Bloom filters'
 	test_bloom_filters_not_used "-- file4 A/file1"
 '
 
+test_expect_success 'git log -- "." pathspec at root does not use Bloom filters' '
+	test_bloom_filters_not_used "-- ."
+'
+
 test_expect_success 'git log with wildcard that resolves to a single path uses Bloom filters' '
 	test_bloom_filters_used "-- *4" &&
 	test_bloom_filters_used "-- *renamed"