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-rw-r--r--Documentation/technical/commit-graph-format.txt28
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