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commit-reach: add trace2 instrumentation to paint_down_to_common() 

Add a step counter and trace2_data_intmax() call so that the number
of commits visited during the paint walk is observable via
GIT_TRACE2_EVENT. This provides a way to measure the impact of
future optimizations without relying on wall-clock benchmarks alone.

Some step counts already vary across commit-graph modes (e.g.
in_merge_bases_many:self) because the pre-existing min_generation
optimization short-circuits the walk when generation data is
available.

Signed-off-by: Kristofer Karlsson <krka@spotify.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
maint
Kristofer Karlsson 2026-08-11 09:28:47 +00:00 committed by Junio C Hamano
parent 259a45f1f8
commit 6300d71cd6
2 changed files with 36 additions and 13 deletions
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5
commit-reach.c
View File

@ -11,6 +11,7 @@
#include "tag.h"
#include "commit-reach.h"
#include "ewah/ewok.h"
#include "trace2.h"

/* Remember to update object flag allocation in object.h */
#define PARENT1 (1u<<16)
@ -113,6 +114,7 @@ static int paint_down_to_common(struct repository *r,
};
int i;
int gen_ordered = 1;
int steps = 0;
timestamp_t last_gen = GENERATION_NUMBER_INFINITY;
struct commit_list **tail = result;

@ -138,6 +140,7 @@ static int paint_down_to_common(struct repository *r,
struct commit_list *parents;
int flags;
timestamp_t generation = commit_graph_generation(commit);
steps++;

if (min_generation && generation > last_gen)
BUG("bad generation skip %"PRItime" > %"PRItime" at %s",
@ -194,6 +197,8 @@ static int paint_down_to_common(struct repository *r,
}

clear_nonstale_queue(&queue);
trace2_data_intmax("paint_down_to_common", r,
"steps", steps);
commit_list_sort_by_date(result);
return 0;
}

44
t/t6600-test-reach.sh
View File

@ -153,24 +153,34 @@ test_expect_success 'setup' '
'

run_all_modes () {
test_when_finished rm -rf .git/objects/info/commit-graph &&
"$@" <input >actual &&
test_cmp expect actual &&
cp commit-graph-full .git/objects/info/commit-graph &&
"$@" <input >actual &&
test_cmp expect actual &&
cp commit-graph-half .git/objects/info/commit-graph &&
"$@" <input >actual &&
test_cmp expect actual &&
cp commit-graph-no-gdat .git/objects/info/commit-graph &&
"$@" <input >actual &&
test_cmp expect actual
graph=.git/objects/info/commit-graph &&
test_when_finished rm -rf "$graph" "${graph}s" &&
rm -f trace-mode-*.txt &&

for mode in none full half no-gdat
do
rm -rf "$graph" "${graph}s" &&
cp "commit-graph-${mode}" "$graph" 2>/dev/null ||
true &&
GIT_TRACE2_EVENT="$(pwd)/trace-mode-${mode}.txt" \
"$@" <input >actual &&
test_cmp expect actual || return 1
done
}

test_all_modes () {
run_all_modes test-tool reach "$@"
}

test_paint_down_steps () {
for mode in none full half no-gdat
do
test_trace2_data_singular paint_down_to_common steps "$1" \
"mode=$mode" <"trace-mode-${mode}.txt" || return 1
shift
done
}

test_expect_success 'ref_newer:miss' '
cat >input <<-\EOF &&
A:commit-5-7
@ -244,7 +254,8 @@ test_expect_success 'in_merge_bases_many:self' '
X:commit-6-8
EOF
echo "in_merge_bases_many(A,X):1" >expect &&
test_all_modes in_merge_bases_many
test_all_modes in_merge_bases_many &&
test_paint_down_steps 45 2 25 3
'

test_expect_success 'is_descendant_of:hit' '
@ -329,6 +340,13 @@ test_expect_success 'get_merge_bases_many:infinity-both-sides' '
test_all_modes get_merge_bases_many
'

test_expect_success 'merge-base --all commit-walk steps' '
>input &&
git rev-parse commit-9-1 >expect &&
run_all_modes git merge-base --all commit-9-9 commit-9-1 &&
test_paint_down_steps 81 80 81 81
'

test_expect_success 'reduce_heads' '
cat >input <<-\EOF &&
X:commit-1-10