From: Jonathan Tan Date: Tue, 25 Jun 2024 17:39:34 +0000 (-0400) Subject: gitformat-commit-graph: describe version 2 of BDAT X-Git-Tag: v2.46.0-rc0~7^2~12 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=23e91c0ca3f1f700884812990bbfa48d09039b77;p=thirdparty%2Fgit.git gitformat-commit-graph: describe version 2 of BDAT The code change to Git to support version 2 will be done in subsequent commits. Signed-off-by: Jonathan Tan Signed-off-by: Junio C Hamano Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano --- diff --git a/Documentation/gitformat-commit-graph.txt b/Documentation/gitformat-commit-graph.txt index 31cad585e2..3e906e8030 100644 --- a/Documentation/gitformat-commit-graph.txt +++ b/Documentation/gitformat-commit-graph.txt @@ -142,13 +142,16 @@ All multi-byte numbers are in network byte order. ==== Bloom Filter Data (ID: {'B', 'D', 'A', 'T'}) [Optional] * It starts with header consisting of three unsigned 32-bit integers: - - Version of the hash algorithm being used. We currently only support - value 1 which corresponds to the 32-bit version of the murmur3 hash + - Version of the hash algorithm being used. We currently support + value 2 which corresponds to the 32-bit version of the murmur3 hash implemented exactly as described in https://en.wikipedia.org/wiki/MurmurHash#Algorithm and the double hashing technique using seed values 0x293ae76f and 0x7e646e2 as described in https://doi.org/10.1007/978-3-540-30494-4_26 "Bloom Filters - in Probabilistic Verification" + in Probabilistic Verification". Version 1 Bloom filters have a bug that appears + when char is signed and the repository has path names that have characters >= + 0x80; Git supports reading and writing them, but this ability will be removed + in a future version of Git. - The number of times a path is hashed and hence the number of bit positions that cumulatively determine whether a file is present in the commit. - The minimum number of bits 'b' per entry in the Bloom filter. If the filter