| #ifndef PACK_REVINDEX_H |
| #define PACK_REVINDEX_H |
| |
| /** |
| * A revindex allows converting efficiently between three properties |
| * of an object within a pack: |
| * |
| * - index position: the numeric position within the list of sorted object ids |
| * found in the .idx file |
| * |
| * - pack position: the numeric position within the list of objects in their |
| * order within the actual .pack file (i.e., 0 is the first object in the |
| * .pack, 1 is the second, and so on) |
| * |
| * - offset: the byte offset within the .pack file at which the object contents |
| * can be found |
| */ |
| |
| |
| #define RIDX_SIGNATURE 0x52494458 /* "RIDX" */ |
| #define RIDX_VERSION 1 |
| |
| #define GIT_TEST_WRITE_REV_INDEX "GIT_TEST_WRITE_REV_INDEX" |
| #define GIT_TEST_REV_INDEX_DIE_IN_MEMORY "GIT_TEST_REV_INDEX_DIE_IN_MEMORY" |
| |
| struct packed_git; |
| |
| /* |
| * load_pack_revindex populates the revindex's internal data-structures for the |
| * given pack, returning zero on success and a negative value otherwise. |
| * |
| * If a '.rev' file is present it is mmap'd, and pointers are assigned into it |
| * (instead of using the in-memory variant). |
| */ |
| int load_pack_revindex(struct packed_git *p); |
| |
| /* |
| * offset_to_pack_pos converts an object offset to a pack position. This |
| * function returns zero on success, and a negative number otherwise. The |
| * parameter 'pos' is usable only on success. |
| * |
| * If the reverse index has not yet been loaded, this function loads it lazily, |
| * and returns an negative number if an error was encountered. |
| * |
| * This function runs in time O(log N) with the number of objects in the pack. |
| */ |
| int offset_to_pack_pos(struct packed_git *p, off_t ofs, uint32_t *pos); |
| |
| /* |
| * pack_pos_to_index converts the given pack-relative position 'pos' by |
| * returning an index-relative position. |
| * |
| * If the reverse index has not yet been loaded, or the position is out of |
| * bounds, this function aborts. |
| * |
| * This function runs in constant time. |
| */ |
| uint32_t pack_pos_to_index(struct packed_git *p, uint32_t pos); |
| |
| /* |
| * pack_pos_to_offset converts the given pack-relative position 'pos' into a |
| * pack offset. For a pack with 'N' objects, asking for position 'N' will return |
| * the total size (in bytes) of the pack. |
| * |
| * If the reverse index has not yet been loaded, or the position is out of |
| * bounds, this function aborts. |
| * |
| * This function runs in constant time under both in-memory and on-disk reverse |
| * indexes, but an additional step is taken to consult the corresponding .idx |
| * file when using the on-disk format. |
| */ |
| off_t pack_pos_to_offset(struct packed_git *p, uint32_t pos); |
| |
| #endif |