pack-objects: clarify the use of object_entry::size
[git/git.git] / pack-objects.h
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1#ifndef PACK_OBJECTS_H
2#define PACK_OBJECTS_H
3
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4#include "object-store.h"
5
0c6804ab 6#define OE_DFS_STATE_BITS 2
b5c0cbd8 7#define OE_DEPTH_BITS 12
43fa44fa 8#define OE_IN_PACK_BITS 10
0cb3c142 9#define OE_Z_DELTA_BITS 20
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10
11/*
12 * State flags for depth-first search used for analyzing delta cycles.
13 *
14 * The depth is measured in delta-links to the base (so if A is a delta
15 * against B, then A has a depth of 1, and B a depth of 0).
16 */
17enum dfs_state {
18 DFS_NONE = 0,
19 DFS_ACTIVE,
20 DFS_DONE,
21 DFS_NUM_STATES
22};
23
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24/*
25 * basic object info
26 * -----------------
27 * idx.oid is filled up before delta searching starts. idx.crc32 is
28 * only valid after the object is written out and will be used for
29 * generating the index. idx.offset will be both gradually set and
30 * used in writing phase (base objects get offset first, then deltas
31 * refer to them)
32 *
33 * "size" is the uncompressed object size. Compressed size of the raw
34 * data for an object in a pack is not stored anywhere but is computed
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35 * and made available when reverse .idx is made. Note that when a
36 * delta is reused, "size" is the uncompressed _delta_ size, not the
37 * canonical one after the delta has been applied.
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38 *
39 * "hash" contains a path name hash which is used for sorting the
40 * delta list and also during delta searching. Once prepare_pack()
41 * returns it's no longer needed.
42 *
43 * source pack info
44 * ----------------
45 * The (in_pack, in_pack_offset) tuple contains the location of the
46 * object in the source pack. in_pack_header_size allows quickly
47 * skipping the header and going straight to the zlib stream.
48 *
49 * "type" and "in_pack_type" both describe object type. in_pack_type
50 * may contain a delta type, while type is always the canonical type.
51 *
52 * deltas
53 * ------
54 * Delta links (delta, delta_child and delta_sibling) are created to
55 * reflect that delta graph from the source pack then updated or added
56 * during delta searching phase when we find better deltas.
57 *
58 * delta_child and delta_sibling are last needed in
59 * compute_write_order(). "delta" and "delta_size" must remain valid
60 * at object writing phase in case the delta is not cached.
61 *
62 * If a delta is cached in memory and is compressed, delta_data points
63 * to the data and z_delta_size contains the compressed size. If it's
64 * uncompressed [1], z_delta_size must be zero. delta_size is always
65 * the uncompressed size and must be valid even if the delta is not
66 * cached.
67 *
68 * [1] during try_delta phase we don't bother with compressing because
69 * the delta could be quickly replaced with a better one.
70 */
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71struct object_entry {
72 struct pack_idx_entry idx;
73 unsigned long size; /* uncompressed size */
43fa44fa 74 unsigned in_pack_idx:OE_IN_PACK_BITS; /* already in pack */
2834bc27 75 off_t in_pack_offset;
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76 uint32_t delta_idx; /* delta base object */
77 uint32_t delta_child_idx; /* deltified objects who bases me */
78 uint32_t delta_sibling_idx; /* other deltified objects who
79 * uses the same base as me
80 */
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81 void *delta_data; /* cached delta (uncompressed) */
82 unsigned long delta_size; /* delta data size (uncompressed) */
0cb3c142 83 unsigned z_delta_size:OE_Z_DELTA_BITS;
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84 unsigned type_:TYPE_BITS;
85 unsigned in_pack_type:TYPE_BITS; /* could be delta */
86 unsigned type_valid:1;
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87 uint32_t hash; /* name hint hash */
88 unsigned char in_pack_header_size;
89 unsigned preferred_base:1; /*
90 * we do not pack this, but is available
91 * to be used as the base object to delta
92 * objects against.
93 */
94 unsigned no_try_delta:1;
95 unsigned tagged:1; /* near the very tip of refs */
96 unsigned filled:1; /* assigned write-order */
0c6804ab 97 unsigned dfs_state:OE_DFS_STATE_BITS;
b5c0cbd8 98 unsigned depth:OE_DEPTH_BITS;
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99};
100
101struct packing_data {
102 struct object_entry *objects;
103 uint32_t nr_objects, nr_alloc;
104
105 int32_t *index;
106 uint32_t index_size;
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107
108 unsigned int *in_pack_pos;
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109
110 /*
111 * Only one of these can be non-NULL and they have different
112 * sizes. if in_pack_by_idx is allocated, oe_in_pack() returns
113 * the pack of an object using in_pack_idx field. If not,
114 * in_pack[] array is used the same way as in_pack_pos[]
115 */
116 struct packed_git **in_pack_by_idx;
117 struct packed_git **in_pack;
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118};
119
43fa44fa 120void prepare_packing_data(struct packing_data *pdata);
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121struct object_entry *packlist_alloc(struct packing_data *pdata,
122 const unsigned char *sha1,
123 uint32_t index_pos);
124
125struct object_entry *packlist_find(struct packing_data *pdata,
126 const unsigned char *sha1,
127 uint32_t *index_pos);
128
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129static inline uint32_t pack_name_hash(const char *name)
130{
131 uint32_t c, hash = 0;
132
133 if (!name)
134 return 0;
135
136 /*
137 * This effectively just creates a sortable number from the
138 * last sixteen non-whitespace characters. Last characters
139 * count "most", so things that end in ".c" sort together.
140 */
141 while ((c = *name++) != 0) {
142 if (isspace(c))
143 continue;
144 hash = (hash >> 2) + (c << 24);
145 }
146 return hash;
147}
148
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149static inline enum object_type oe_type(const struct object_entry *e)
150{
151 return e->type_valid ? e->type_ : OBJ_BAD;
152}
153
154static inline void oe_set_type(struct object_entry *e,
155 enum object_type type)
156{
157 if (type >= OBJ_ANY)
158 BUG("OBJ_ANY cannot be set in pack-objects code");
159
160 e->type_valid = type >= OBJ_NONE;
161 e->type_ = (unsigned)type;
162}
163
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164static inline unsigned int oe_in_pack_pos(const struct packing_data *pack,
165 const struct object_entry *e)
166{
167 return pack->in_pack_pos[e - pack->objects];
168}
169
170static inline void oe_set_in_pack_pos(const struct packing_data *pack,
171 const struct object_entry *e,
172 unsigned int pos)
173{
174 pack->in_pack_pos[e - pack->objects] = pos;
175}
176
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177static inline struct packed_git *oe_in_pack(const struct packing_data *pack,
178 const struct object_entry *e)
179{
180 if (pack->in_pack_by_idx)
181 return pack->in_pack_by_idx[e->in_pack_idx];
182 else
183 return pack->in_pack[e - pack->objects];
184}
185
186void oe_map_new_pack(struct packing_data *pack,
187 struct packed_git *p);
188static inline void oe_set_in_pack(struct packing_data *pack,
189 struct object_entry *e,
190 struct packed_git *p)
191{
192 if (!p->index)
193 oe_map_new_pack(pack, p);
194 if (pack->in_pack_by_idx)
195 e->in_pack_idx = p->index;
196 else
197 pack->in_pack[e - pack->objects] = p;
198}
199
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200static inline struct object_entry *oe_delta(
201 const struct packing_data *pack,
202 const struct object_entry *e)
203{
204 if (e->delta_idx)
205 return &pack->objects[e->delta_idx - 1];
206 return NULL;
207}
208
209static inline void oe_set_delta(struct packing_data *pack,
210 struct object_entry *e,
211 struct object_entry *delta)
212{
213 if (delta)
214 e->delta_idx = (delta - pack->objects) + 1;
215 else
216 e->delta_idx = 0;
217}
218
219static inline struct object_entry *oe_delta_child(
220 const struct packing_data *pack,
221 const struct object_entry *e)
222{
223 if (e->delta_child_idx)
224 return &pack->objects[e->delta_child_idx - 1];
225 return NULL;
226}
227
228static inline void oe_set_delta_child(struct packing_data *pack,
229 struct object_entry *e,
230 struct object_entry *delta)
231{
232 if (delta)
233 e->delta_child_idx = (delta - pack->objects) + 1;
234 else
235 e->delta_child_idx = 0;
236}
237
238static inline struct object_entry *oe_delta_sibling(
239 const struct packing_data *pack,
240 const struct object_entry *e)
241{
242 if (e->delta_sibling_idx)
243 return &pack->objects[e->delta_sibling_idx - 1];
244 return NULL;
245}
246
247static inline void oe_set_delta_sibling(struct packing_data *pack,
248 struct object_entry *e,
249 struct object_entry *delta)
250{
251 if (delta)
252 e->delta_sibling_idx = (delta - pack->objects) + 1;
253 else
254 e->delta_sibling_idx = 0;
255}
256
2834bc27 257#endif