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| author | Junio C Hamano <gitster@pobox.com> | 2021-02-17 17:21:40 -0800 |
|---|---|---|
| committer | Junio C Hamano <gitster@pobox.com> | 2021-02-17 17:21:40 -0800 |
| commit | 8b4701ae4fa8e68362509013ceb496333b7ca0df (patch) | |
| tree | 3f34f7368739f10ec4c776d6b2a8d7345479c8d6 /Documentation/technical/commit-graph-format.txt | |
| parent | 328c10930387d301560f7cbcd3351cc485a13381 (diff) | |
| parent | 5a3b130cad0d5c770f766e3af6d32b41766374c0 (diff) | |
| download | git-8b4701ae4fa8e68362509013ceb496333b7ca0df.tar.gz | |
Merge branch 'ak/corrected-commit-date'
The commit-graph learned to use corrected commit dates instead of
the generation number to help topological revision traversal.
* ak/corrected-commit-date:
doc: add corrected commit date info
commit-reach: use corrected commit dates in paint_down_to_common()
commit-graph: use generation v2 only if entire chain does
commit-graph: implement generation data chunk
commit-graph: implement corrected commit date
commit-graph: return 64-bit generation number
commit-graph: add a slab to store topological levels
t6600-test-reach: generalize *_three_modes
commit-graph: consolidate fill_commit_graph_info
revision: parse parent in indegree_walk_step()
commit-graph: fix regression when computing Bloom filters
Diffstat (limited to 'Documentation/technical/commit-graph-format.txt')
| -rw-r--r-- | Documentation/technical/commit-graph-format.txt | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/Documentation/technical/commit-graph-format.txt b/Documentation/technical/commit-graph-format.txt index b3b58880b9..b6658eff18 100644 --- a/Documentation/technical/commit-graph-format.txt +++ b/Documentation/technical/commit-graph-format.txt @@ -4,11 +4,7 @@ Git commit graph format The Git commit graph stores a list of commit OIDs and some associated metadata, including: -- The generation number of the commit. Commits with no parents have - generation number 1; commits with parents have generation number - one more than the maximum generation number of its parents. We - reserve zero as special, and can be used to mark a generation - number invalid or as "not computed". +- The generation number of the commit. - The root tree OID. @@ -86,13 +82,33 @@ CHUNK DATA: position. If there are more than two parents, the second value has its most-significant bit on and the other bits store an array position into the Extra Edge List chunk. - * The next 8 bytes store the generation number of the commit and + * The next 8 bytes store the topological level (generation number v1) + of the commit and the commit time in seconds since EPOCH. The generation number uses the higher 30 bits of the first 4 bytes, while the commit time uses the 32 bits of the second 4 bytes, along with the lowest 2 bits of the lowest byte, storing the 33rd and 34th bit of the commit time. + Generation Data (ID: {'G', 'D', 'A', 'T' }) (N * 4 bytes) [Optional] + * This list of 4-byte values store corrected commit date offsets for the + commits, arranged in the same order as commit data chunk. + * If the corrected commit date offset cannot be stored within 31 bits, + the value has its most-significant bit on and the other bits store + the position of corrected commit date into the Generation Data Overflow + chunk. + * Generation Data chunk is present only when commit-graph file is written + by compatible versions of Git and in case of split commit-graph chains, + the topmost layer also has Generation Data chunk. + + Generation Data Overflow (ID: {'G', 'D', 'O', 'V' }) [Optional] + * This list of 8-byte values stores the corrected commit date offsets + for commits with corrected commit date offsets that cannot be + stored within 31 bits. + * Generation Data Overflow chunk is present only when Generation Data + chunk is present and atleast one corrected commit date offset cannot + be stored within 31 bits. + Extra Edge List (ID: {'E', 'D', 'G', 'E'}) [Optional] This list of 4-byte values store the second through nth parents for all octopus merges. The second parent value in the commit data stores |