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author | Derrick Stolee <derrickstolee@github.com> | 2022-03-01 22:48:30 +0300 |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2022-03-01 23:14:57 +0300 |
commit | 75979d94607d92d53b1cad5d65f20594c66d275c (patch) | |
tree | 2d5b0849bd5e208144bf9f127e768a53a3d66a7f | |
parent | 17925e0602983b1a1dbdd418c2fc2c70ca5faf5b (diff) |
commit-graph: fix ordering bug in generation numbers
When computing the generation numbers for a commit-graph, we compute
the corrected commit dates and then check if their offsets from the
actual dates is too large to fit in the 32-bit Generation Data chunk.
However, there is a problem with this approach: if we have parsed the
generation data from the previous commit-graph, then we continue the
loop because the corrected commit date is already computed. This causes
an under-count in the number of overflow values.
It is incorrect to add an increment to num_generation_data_overflows
next to this 'continue' statement, because we might start
double-counting commits that are computed because of the depth-first
search walk from a commit with an earlier OID.
Instead, iterate over the full commit list at the end, checking the
offsets to see how many grow beyond the maximum value.
Create a new t5328-commit-graph-64-bit-time.sh test script to handle
special cases of testing 64-bit timestamps. This helps demonstrate this
bug in more cases. It still won't hit all potential cases until the next
change, which reenables reading generation numbers. Use the skip_all
trick from 0a2bfccb9c8 (t0051: use "skip_all" under !MINGW in
single-test file, 2022-02-04) to make the output clean when run on a
32-bit system.
Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r-- | commit-graph.c | 10 | ||||
-rwxr-xr-x | t/t5318-commit-graph.sh | 4 | ||||
-rwxr-xr-x | t/t5328-commit-graph-64bit-time.sh | 39 |
3 files changed, 48 insertions, 5 deletions
diff --git a/commit-graph.c b/commit-graph.c index 265c010122..a19bd96c2e 100644 --- a/commit-graph.c +++ b/commit-graph.c @@ -1556,12 +1556,16 @@ static void compute_generation_numbers(struct write_commit_graph_context *ctx) if (current->date && current->date > max_corrected_commit_date) max_corrected_commit_date = current->date - 1; commit_graph_data_at(current)->generation = max_corrected_commit_date + 1; - - if (commit_graph_data_at(current)->generation - current->date > GENERATION_NUMBER_V2_OFFSET_MAX) - ctx->num_generation_data_overflows++; } } } + + for (i = 0; i < ctx->commits.nr; i++) { + struct commit *c = ctx->commits.list[i]; + timestamp_t offset = commit_graph_data_at(c)->generation - c->date; + if (offset > GENERATION_NUMBER_V2_OFFSET_MAX) + ctx->num_generation_data_overflows++; + } stop_progress(&ctx->progress); } diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh index 9e2b5884da..0ed7e9de8e 100755 --- a/t/t5318-commit-graph.sh +++ b/t/t5318-commit-graph.sh @@ -425,10 +425,10 @@ test_expect_success 'warn on improper hash version' ' ) ' -test_expect_success 'lower layers have overflow chunk' ' +test_expect_success TIME_IS_64BIT,TIME_T_IS_64BIT 'lower layers have overflow chunk' ' cd "$TRASH_DIRECTORY/full" && UNIX_EPOCH_ZERO="@0 +0000" && - FUTURE_DATE="@2147483646 +0000" && + FUTURE_DATE="@4147483646 +0000" && rm -f .git/objects/info/commit-graph && test_commit --date "$FUTURE_DATE" future-1 && test_commit --date "$UNIX_EPOCH_ZERO" old-1 && diff --git a/t/t5328-commit-graph-64bit-time.sh b/t/t5328-commit-graph-64bit-time.sh new file mode 100755 index 0000000000..28114bcaf4 --- /dev/null +++ b/t/t5328-commit-graph-64bit-time.sh @@ -0,0 +1,39 @@ +#!/bin/sh + +test_description='commit graph with 64-bit timestamps' +. ./test-lib.sh + +if ! test_have_prereq TIME_IS_64BIT || ! test_have_prereq TIME_T_IS_64BIT +then + skip_all='skipping 64-bit timestamp tests' + test_done +fi + +. "$TEST_DIRECTORY"/lib-commit-graph.sh + +UNIX_EPOCH_ZERO="@0 +0000" +FUTURE_DATE="@4147483646 +0000" + +GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS=0 + +test_expect_success 'lower layers have overflow chunk' ' + rm -f .git/objects/info/commit-graph && + test_commit --date "$FUTURE_DATE" future-1 && + test_commit --date "$UNIX_EPOCH_ZERO" old-1 && + git commit-graph write --reachable && + test_commit --date "$FUTURE_DATE" future-2 && + test_commit --date "$UNIX_EPOCH_ZERO" old-2 && + git commit-graph write --reachable --split=no-merge && + test_commit extra && + git commit-graph write --reachable --split=no-merge && + git commit-graph write --reachable && + graph_read_expect 5 "generation_data generation_data_overflow" && + mv .git/objects/info/commit-graph commit-graph-upgraded && + git commit-graph write --reachable && + graph_read_expect 5 "generation_data generation_data_overflow" && + test_cmp .git/objects/info/commit-graph commit-graph-upgraded +' + +graph_git_behavior 'overflow' '' HEAD~2 HEAD + +test_done |