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| author |  Junio C Hamano <gitster@pobox.com> | 2012-05-02 13:51:13 -0700 |
|---|---|---|
| committer | Junio C Hamano <gitster@pobox.com> | 2012-05-02 13:51:13 -0700 |
| commit | d4a5d872c05057c415347896bd416006153e4b03 (patch) | |
| tree | 1719741d8f0743b11c5aa27a73d0e0132fc68b4b /Documentation/technical | |
| parent | Merge branch 'master' of https://github.com/git-l10n/git-po (diff) | |
| parent | index-v4: document the entry format (diff) | |
| download | tgif-d4a5d872c05057c415347896bd416006153e4b03.tar.xz | |
Merge branch 'jc/index-v4'
Trivially shrinks the on-disk size of the index file to save both I/O and
checksum overhead.
The topic should give a solid base to build on further updates, with the
code refactoring in its earlier parts, and the backward compatibility
mechanism in its later parts.
* jc/index-v4:
index-v4: document the entry format
unpack-trees: preserve the index file version of original
update-index: upgrade/downgrade on-disk index version
read-cache.c: write prefix-compressed names in the index
read-cache.c: read prefix-compressed names in index on-disk version v4
read-cache.c: move code to copy incore to ondisk cache to a helper function
read-cache.c: move code to copy ondisk to incore cache to a helper function
read-cache.c: report the header version we do not understand
read-cache.c: make create_from_disk() report number of bytes it consumed
read-cache.c: allow unaligned mapping of the index file
cache.h: hide on-disk index details
varint: make it available outside the context of pack
Diffstat (limited to 'Documentation/technical')
| -rw-r--r-- | Documentation/technical/index-format.txt | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/technical/index-format.txt b/Documentation/technical/index-format.txt index 8930b3fabc..9d25b30178 100644 --- a/Documentation/technical/index-format.txt +++ b/Documentation/technical/index-format.txt @@ -113,9 +113,22 @@ GIT index format are encoded in 7-bit ASCII and the encoding cannot contain a NUL byte (iow, this is a UNIX pathname). + (Version 4) In version 4, the entry path name is prefix-compressed + relative to the path name for the previous entry (the very first + entry is encoded as if the path name for the previous entry is an + empty string). At the beginning of an entry, an integer N in the + variable width encoding (the same encoding as the offset is encoded + for OFS_DELTA pack entries; see pack-format.txt) is stored, followed + by a NUL-terminated string S. Removing N bytes from the end of the + path name for the previous entry, and replacing it with the string S + yields the path name for this entry. + 1-8 nul bytes as necessary to pad the entry to a multiple of eight bytes while keeping the name NUL-terminated. + (Version 4) In version 4, the padding after the pathname does not + exist. + == Extensions === Cached tree |