| commit | 898eba5e630696608ddca0ede489378e87464ad6 | [log] [tgz] |
|---|---|---|
| author | Nguyễn Thái Ngọc Duy <pclouds@gmail.com> | Sat Apr 14 17:35:06 2018 +0200 |
| committer | Junio C Hamano <gitster@pobox.com> | Mon Apr 16 12:38:58 2018 +0900 |
| tree | 6c932809a3def3b470165853c006ee2f57d78e03 | |
| parent | 43fa44fa3b68e6570145126892e1e43380d7bb5a [diff] |
pack-objects: refer to delta objects by index instead of pointer
These delta pointers always point to elements in the objects[] array
in packing_data struct. We can only hold maximum 4G of those objects
because the array size in nr_objects is uint32_t. We could use
uint32_t indexes to address these elements instead of pointers. On
64-bit architecture (8 bytes per pointer) this would save 4 bytes per
pointer.
Convert these delta pointers to indexes. Since we need to handle NULL
pointers as well, the index is shifted by one [1].
[1] This means we can only index 2^32-2 objects even though nr_objects
could contain 2^32-1 objects. It should not be a problem in
practice because when we grow objects[], nr_alloc would probably
blow up long before nr_objects hits the wall.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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