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3449f8c4 NP |
1 | #ifndef PACK_REVINDEX_H |
2 | #define PACK_REVINDEX_H | |
3 | ||
f33fb6e4 TB |
4 | /** |
5 | * A revindex allows converting efficiently between three properties | |
6 | * of an object within a pack: | |
7 | * | |
8 | * - index position: the numeric position within the list of sorted object ids | |
9 | * found in the .idx file | |
10 | * | |
11 | * - pack position: the numeric position within the list of objects in their | |
12 | * order within the actual .pack file (i.e., 0 is the first object in the | |
13 | * .pack, 1 is the second, and so on) | |
14 | * | |
15 | * - offset: the byte offset within the .pack file at which the object contents | |
16 | * can be found | |
f894081d TB |
17 | * |
18 | * The revindex can also be used with a multi-pack index (MIDX). In this | |
19 | * setting: | |
20 | * | |
21 | * - index position refers to an object's numeric position within the MIDX | |
22 | * | |
23 | * - pack position refers to an object's position within a non-existent pack | |
24 | * described by the MIDX. The pack structure is described in | |
977c47b4 | 25 | * gitformat-pack(5). |
f894081d TB |
26 | * |
27 | * It is effectively a concatanation of all packs in the MIDX (ordered by | |
28 | * their numeric ID within the MIDX) in their original order within each | |
29 | * pack), removing duplicates, and placing the preferred pack (if any) | |
30 | * first. | |
f33fb6e4 TB |
31 | */ |
32 | ||
e8c58f89 | 33 | |
2f4ba2a8 TB |
34 | #define RIDX_SIGNATURE 0x52494458 /* "RIDX" */ |
35 | #define RIDX_VERSION 1 | |
36 | ||
9f7f10a2 | 37 | #define GIT_TEST_NO_WRITE_REV_INDEX "GIT_TEST_NO_WRITE_REV_INDEX" |
ec8e7760 | 38 | #define GIT_TEST_REV_INDEX_DIE_IN_MEMORY "GIT_TEST_REV_INDEX_DIE_IN_MEMORY" |
2a250d61 | 39 | #define GIT_TEST_REV_INDEX_DIE_ON_DISK "GIT_TEST_REV_INDEX_DIE_ON_DISK" |
e8c58f89 | 40 | |
9d98bbf5 | 41 | struct packed_git; |
f894081d | 42 | struct multi_pack_index; |
65308ad8 | 43 | struct repository; |
9d98bbf5 | 44 | |
f33fb6e4 TB |
45 | /* |
46 | * load_pack_revindex populates the revindex's internal data-structures for the | |
47 | * given pack, returning zero on success and a negative value otherwise. | |
2f4ba2a8 TB |
48 | * |
49 | * If a '.rev' file is present it is mmap'd, and pointers are assigned into it | |
50 | * (instead of using the in-memory variant). | |
f33fb6e4 | 51 | */ |
65308ad8 | 52 | int load_pack_revindex(struct repository *r, struct packed_git *p); |
92e5c77c | 53 | |
5a6072f6 DS |
54 | /* |
55 | * Specifically load a pack revindex from disk. | |
56 | * | |
57 | * Returns 0 on success, 1 on "no .rev file", and -1 when there is an | |
58 | * error parsing the .rev file. | |
59 | */ | |
60 | int load_pack_revindex_from_disk(struct packed_git *p); | |
61 | ||
0d30feef DS |
62 | /* |
63 | * verify_pack_revindex verifies that the on-disk rev-index for the given | |
64 | * pack-file is the same that would be created if written from scratch. | |
65 | * | |
66 | * A negative number is returned on error. | |
67 | */ | |
68 | int verify_pack_revindex(struct packed_git *p); | |
69 | ||
f894081d TB |
70 | /* |
71 | * load_midx_revindex loads the '.rev' file corresponding to the given | |
72 | * multi-pack index by mmap-ing it and assigning pointers in the | |
73 | * multi_pack_index to point at it. | |
74 | * | |
75 | * A negative number is returned on error. | |
76 | */ | |
77 | int load_midx_revindex(struct multi_pack_index *m); | |
78 | ||
79 | /* | |
80 | * Frees resources associated with a multi-pack reverse index. | |
81 | * | |
82 | * A negative number is returned on error. | |
83 | */ | |
84 | int close_midx_revindex(struct multi_pack_index *m); | |
85 | ||
f33fb6e4 TB |
86 | /* |
87 | * offset_to_pack_pos converts an object offset to a pack position. This | |
88 | * function returns zero on success, and a negative number otherwise. The | |
89 | * parameter 'pos' is usable only on success. | |
90 | * | |
91 | * If the reverse index has not yet been loaded, this function loads it lazily, | |
92 | * and returns an negative number if an error was encountered. | |
93 | * | |
94 | * This function runs in time O(log N) with the number of objects in the pack. | |
95 | */ | |
96 | int offset_to_pack_pos(struct packed_git *p, off_t ofs, uint32_t *pos); | |
97 | ||
98 | /* | |
99 | * pack_pos_to_index converts the given pack-relative position 'pos' by | |
100 | * returning an index-relative position. | |
101 | * | |
102 | * If the reverse index has not yet been loaded, or the position is out of | |
103 | * bounds, this function aborts. | |
104 | * | |
105 | * This function runs in constant time. | |
106 | */ | |
107 | uint32_t pack_pos_to_index(struct packed_git *p, uint32_t pos); | |
108 | ||
109 | /* | |
110 | * pack_pos_to_offset converts the given pack-relative position 'pos' into a | |
111 | * pack offset. For a pack with 'N' objects, asking for position 'N' will return | |
112 | * the total size (in bytes) of the pack. | |
113 | * | |
114 | * If the reverse index has not yet been loaded, or the position is out of | |
115 | * bounds, this function aborts. | |
116 | * | |
2f4ba2a8 TB |
117 | * This function runs in constant time under both in-memory and on-disk reverse |
118 | * indexes, but an additional step is taken to consult the corresponding .idx | |
119 | * file when using the on-disk format. | |
f33fb6e4 TB |
120 | */ |
121 | off_t pack_pos_to_offset(struct packed_git *p, uint32_t pos); | |
122 | ||
f894081d TB |
123 | /* |
124 | * pack_pos_to_midx converts the object at position "pos" within the MIDX | |
125 | * pseudo-pack into a MIDX position. | |
126 | * | |
127 | * If the reverse index has not yet been loaded, or the position is out of | |
128 | * bounds, this function aborts. | |
129 | * | |
afb32e81 | 130 | * This function runs in constant time. |
f894081d TB |
131 | */ |
132 | uint32_t pack_pos_to_midx(struct multi_pack_index *m, uint32_t pos); | |
133 | ||
134 | /* | |
135 | * midx_to_pack_pos converts from the MIDX-relative position at "at" to the | |
136 | * corresponding pack position. | |
137 | * | |
138 | * If the reverse index has not yet been loaded, or the position is out of | |
139 | * bounds, this function aborts. | |
140 | * | |
afb32e81 | 141 | * This function runs in time O(log N) with the number of objects in the MIDX. |
f894081d TB |
142 | */ |
143 | int midx_to_pack_pos(struct multi_pack_index *midx, uint32_t at, uint32_t *pos); | |
144 | ||
3449f8c4 | 145 | #endif |