pack-objects: move in_pack_pos out of struct object_entry
[git/git.git] / pack-objects.h
1 #ifndef PACK_OBJECTS_H
2 #define PACK_OBJECTS_H
3
4 #define OE_DFS_STATE_BITS 2
5 #define OE_DEPTH_BITS 12
6
7 /*
8 * State flags for depth-first search used for analyzing delta cycles.
9 *
10 * The depth is measured in delta-links to the base (so if A is a delta
11 * against B, then A has a depth of 1, and B a depth of 0).
12 */
13 enum dfs_state {
14 DFS_NONE = 0,
15 DFS_ACTIVE,
16 DFS_DONE,
17 DFS_NUM_STATES
18 };
19
20 /*
21 * basic object info
22 * -----------------
23 * idx.oid is filled up before delta searching starts. idx.crc32 is
24 * only valid after the object is written out and will be used for
25 * generating the index. idx.offset will be both gradually set and
26 * used in writing phase (base objects get offset first, then deltas
27 * refer to them)
28 *
29 * "size" is the uncompressed object size. Compressed size of the raw
30 * data for an object in a pack is not stored anywhere but is computed
31 * and made available when reverse .idx is made.
32 *
33 * "hash" contains a path name hash which is used for sorting the
34 * delta list and also during delta searching. Once prepare_pack()
35 * returns it's no longer needed.
36 *
37 * source pack info
38 * ----------------
39 * The (in_pack, in_pack_offset) tuple contains the location of the
40 * object in the source pack. in_pack_header_size allows quickly
41 * skipping the header and going straight to the zlib stream.
42 *
43 * "type" and "in_pack_type" both describe object type. in_pack_type
44 * may contain a delta type, while type is always the canonical type.
45 *
46 * deltas
47 * ------
48 * Delta links (delta, delta_child and delta_sibling) are created to
49 * reflect that delta graph from the source pack then updated or added
50 * during delta searching phase when we find better deltas.
51 *
52 * delta_child and delta_sibling are last needed in
53 * compute_write_order(). "delta" and "delta_size" must remain valid
54 * at object writing phase in case the delta is not cached.
55 *
56 * If a delta is cached in memory and is compressed, delta_data points
57 * to the data and z_delta_size contains the compressed size. If it's
58 * uncompressed [1], z_delta_size must be zero. delta_size is always
59 * the uncompressed size and must be valid even if the delta is not
60 * cached.
61 *
62 * [1] during try_delta phase we don't bother with compressing because
63 * the delta could be quickly replaced with a better one.
64 */
65 struct object_entry {
66 struct pack_idx_entry idx;
67 unsigned long size; /* uncompressed size */
68 struct packed_git *in_pack; /* already in pack */
69 off_t in_pack_offset;
70 struct object_entry *delta; /* delta base object */
71 struct object_entry *delta_child; /* deltified objects who bases me */
72 struct object_entry *delta_sibling; /* other deltified objects who
73 * uses the same base as me
74 */
75 void *delta_data; /* cached delta (uncompressed) */
76 unsigned long delta_size; /* delta data size (uncompressed) */
77 unsigned long z_delta_size; /* delta data size (compressed) */
78 unsigned type_:TYPE_BITS;
79 unsigned in_pack_type:TYPE_BITS; /* could be delta */
80 unsigned type_valid:1;
81 uint32_t hash; /* name hint hash */
82 unsigned char in_pack_header_size;
83 unsigned preferred_base:1; /*
84 * we do not pack this, but is available
85 * to be used as the base object to delta
86 * objects against.
87 */
88 unsigned no_try_delta:1;
89 unsigned tagged:1; /* near the very tip of refs */
90 unsigned filled:1; /* assigned write-order */
91 unsigned dfs_state:OE_DFS_STATE_BITS;
92 unsigned depth:OE_DEPTH_BITS;
93 };
94
95 struct packing_data {
96 struct object_entry *objects;
97 uint32_t nr_objects, nr_alloc;
98
99 int32_t *index;
100 uint32_t index_size;
101
102 unsigned int *in_pack_pos;
103 };
104
105 struct object_entry *packlist_alloc(struct packing_data *pdata,
106 const unsigned char *sha1,
107 uint32_t index_pos);
108
109 struct object_entry *packlist_find(struct packing_data *pdata,
110 const unsigned char *sha1,
111 uint32_t *index_pos);
112
113 static inline uint32_t pack_name_hash(const char *name)
114 {
115 uint32_t c, hash = 0;
116
117 if (!name)
118 return 0;
119
120 /*
121 * This effectively just creates a sortable number from the
122 * last sixteen non-whitespace characters. Last characters
123 * count "most", so things that end in ".c" sort together.
124 */
125 while ((c = *name++) != 0) {
126 if (isspace(c))
127 continue;
128 hash = (hash >> 2) + (c << 24);
129 }
130 return hash;
131 }
132
133 static inline enum object_type oe_type(const struct object_entry *e)
134 {
135 return e->type_valid ? e->type_ : OBJ_BAD;
136 }
137
138 static inline void oe_set_type(struct object_entry *e,
139 enum object_type type)
140 {
141 if (type >= OBJ_ANY)
142 BUG("OBJ_ANY cannot be set in pack-objects code");
143
144 e->type_valid = type >= OBJ_NONE;
145 e->type_ = (unsigned)type;
146 }
147
148 static inline unsigned int oe_in_pack_pos(const struct packing_data *pack,
149 const struct object_entry *e)
150 {
151 return pack->in_pack_pos[e - pack->objects];
152 }
153
154 static inline void oe_set_in_pack_pos(const struct packing_data *pack,
155 const struct object_entry *e,
156 unsigned int pos)
157 {
158 pack->in_pack_pos[e - pack->objects] = pos;
159 }
160
161 #endif