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author | Taylor Blau <me@ttaylorr.com> | 2024-04-29 16:43:52 -0400 |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2024-04-30 13:00:26 -0700 |
commit | c4e2d37cc639988619f361aa657e6055f6cb2dfd (patch) | |
tree | 01b249d3b7c89a63c26bcc9edebc3fefdc549bc2 | |
parent | 574be802a05d20ecfbc314b669c04777c4a40618 (diff) | |
download | git-c4e2d37cc639988619f361aa657e6055f6cb2dfd.tar.gz |
pseudo-merge: scaffolding for reads
Notice: this object is not reachable from any branch.
Implement scaffolding within the new pseudo-merge compilation unit
necessary to use the pseudo-merge API from within the pack-bitmap.c
machinery.
The core of this scaffolding is two-fold:
- The `pseudo_merge` structure itself, which represents an individual
pseudo-merge bitmap. It has fields for both bitmaps, as well as
metadata about its position within the memory-mapped region, and
a few extra bits indicating whether or not it is satisfied, and
which bitmaps(s, if any) have been read, since they are initialized
lazily.
- The `pseudo_merge_map` structure, which holds an array of
pseudo_merges, as well as a pointer to the memory-mapped region
containing the pseudo-merge serialization from within a .bitmap
file.
Note that the `bitmap_index` structure is defined statically within the
pack-bitmap.o compilation unit, so we can't take in a `struct
bitmap_index *`. Instead, wrap the primary components necessary to read
the pseudo-merges in this new structure to avoid exposing the
implementation details of the `bitmap_index` structure.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Notice: this object is not reachable from any branch.
-rw-r--r-- | pseudo-merge.c | 10 | ||||
-rw-r--r-- | pseudo-merge.h | 65 |
2 files changed, 75 insertions, 0 deletions
diff --git a/pseudo-merge.c b/pseudo-merge.c index caccef942a..d18de0a266 100644 --- a/pseudo-merge.c +++ b/pseudo-merge.c @@ -441,3 +441,13 @@ void select_pseudo_merges(struct string_list *list, stop_progress(&progress); } + +void free_pseudo_merge_map(struct pseudo_merge_map *pm) +{ + uint32_t i; + for (i = 0; i < pm->nr; i++) { + ewah_pool_free(pm->v[i].commits); + ewah_pool_free(pm->v[i].bitmap); + } + free(pm->v); +} diff --git a/pseudo-merge.h b/pseudo-merge.h index 8188873186..2f652fc676 100644 --- a/pseudo-merge.h +++ b/pseudo-merge.h @@ -99,4 +99,69 @@ void select_pseudo_merges(struct string_list *list, uint32_t *pseudo_merges_nr, unsigned show_progress); +/* + * Represents a serialized view of a file containing pseudo-merge(s) + * (see Documentation/technical/bitmap-format.txt for a specification + * of the format). + */ +struct pseudo_merge_map { + /* + * An array of pseudo-merge(s), lazily loaded from the .bitmap + * file. + */ + struct pseudo_merge *v; + size_t nr; + size_t commits_nr; + + /* + * Pointers into a memory-mapped view of the .bitmap file: + * + * - map: the beginning of the .bitmap file + * - commits: the beginning of the pseudo-merge commit index + * - map_size: the size of the .bitmap file + */ + const unsigned char *map; + const unsigned char *commits; + + size_t map_size; +}; + +/* + * An individual pseudo-merge, storing a pair of lazily-loaded + * bitmaps: + * + * - commits: the set of commit(s) that are part of the pseudo-merge + * - bitmap: the set of object(s) reachable from the above set of + * commits. + * + * The `at` and `bitmap_at` fields are used to store the locations of + * each of the above bitmaps in the .bitmap file. + */ +struct pseudo_merge { + struct ewah_bitmap *commits; + struct ewah_bitmap *bitmap; + + off_t at; + off_t bitmap_at; + + /* + * `satisfied` indicates whether the given pseudo-merge has been + * used. + * + * `loaded_commits` and `loaded_bitmap` indicate whether the + * respective bitmaps have been loaded and read from the + * .bitmap file. + */ + unsigned satisfied : 1, + loaded_commits : 1, + loaded_bitmap : 1; +}; + +/* + * Frees the given pseudo-merge map, releasing any memory held by (a) + * parsed EWAH bitmaps, or (b) the array of pseudo-merges itself. Does + * not free the memory-mapped view of the .bitmap file. + */ +void free_pseudo_merge_map(struct pseudo_merge_map *pm); + #endif |