pack-objects: shrink size field in struct object_entry
[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 * Note that oe_set_size() becomes expensive when the given size is
12 * above this limit. Don't lower it too much.
13 */
14#define OE_SIZE_BITS 31
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15
16/*
17 * State flags for depth-first search used for analyzing delta cycles.
18 *
19 * The depth is measured in delta-links to the base (so if A is a delta
20 * against B, then A has a depth of 1, and B a depth of 0).
21 */
22enum dfs_state {
23 DFS_NONE = 0,
24 DFS_ACTIVE,
25 DFS_DONE,
26 DFS_NUM_STATES
27};
28
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29/*
30 * basic object info
31 * -----------------
32 * idx.oid is filled up before delta searching starts. idx.crc32 is
33 * only valid after the object is written out and will be used for
34 * generating the index. idx.offset will be both gradually set and
35 * used in writing phase (base objects get offset first, then deltas
36 * refer to them)
37 *
38 * "size" is the uncompressed object size. Compressed size of the raw
39 * data for an object in a pack is not stored anywhere but is computed
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40 * and made available when reverse .idx is made. Note that when a
41 * delta is reused, "size" is the uncompressed _delta_ size, not the
42 * canonical one after the delta has been applied.
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43 *
44 * "hash" contains a path name hash which is used for sorting the
45 * delta list and also during delta searching. Once prepare_pack()
46 * returns it's no longer needed.
47 *
48 * source pack info
49 * ----------------
50 * The (in_pack, in_pack_offset) tuple contains the location of the
51 * object in the source pack. in_pack_header_size allows quickly
52 * skipping the header and going straight to the zlib stream.
53 *
54 * "type" and "in_pack_type" both describe object type. in_pack_type
55 * may contain a delta type, while type is always the canonical type.
56 *
57 * deltas
58 * ------
59 * Delta links (delta, delta_child and delta_sibling) are created to
60 * reflect that delta graph from the source pack then updated or added
61 * during delta searching phase when we find better deltas.
62 *
63 * delta_child and delta_sibling are last needed in
64 * compute_write_order(). "delta" and "delta_size" must remain valid
65 * at object writing phase in case the delta is not cached.
66 *
67 * If a delta is cached in memory and is compressed, delta_data points
68 * to the data and z_delta_size contains the compressed size. If it's
69 * uncompressed [1], z_delta_size must be zero. delta_size is always
70 * the uncompressed size and must be valid even if the delta is not
71 * cached.
72 *
73 * [1] during try_delta phase we don't bother with compressing because
74 * the delta could be quickly replaced with a better one.
75 */
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76struct object_entry {
77 struct pack_idx_entry idx;
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78 unsigned size_:OE_SIZE_BITS;
79 unsigned size_valid:1;
43fa44fa 80 unsigned in_pack_idx:OE_IN_PACK_BITS; /* already in pack */
2834bc27 81 off_t in_pack_offset;
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82 uint32_t delta_idx; /* delta base object */
83 uint32_t delta_child_idx; /* deltified objects who bases me */
84 uint32_t delta_sibling_idx; /* other deltified objects who
85 * uses the same base as me
86 */
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87 void *delta_data; /* cached delta (uncompressed) */
88 unsigned long delta_size; /* delta data size (uncompressed) */
0cb3c142 89 unsigned z_delta_size:OE_Z_DELTA_BITS;
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90 unsigned type_:TYPE_BITS;
91 unsigned in_pack_type:TYPE_BITS; /* could be delta */
92 unsigned type_valid:1;
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93 uint32_t hash; /* name hint hash */
94 unsigned char in_pack_header_size;
95 unsigned preferred_base:1; /*
96 * we do not pack this, but is available
97 * to be used as the base object to delta
98 * objects against.
99 */
100 unsigned no_try_delta:1;
101 unsigned tagged:1; /* near the very tip of refs */
102 unsigned filled:1; /* assigned write-order */
0c6804ab 103 unsigned dfs_state:OE_DFS_STATE_BITS;
b5c0cbd8 104 unsigned depth:OE_DEPTH_BITS;
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105};
106
107struct packing_data {
108 struct object_entry *objects;
109 uint32_t nr_objects, nr_alloc;
110
111 int32_t *index;
112 uint32_t index_size;
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113
114 unsigned int *in_pack_pos;
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115
116 /*
117 * Only one of these can be non-NULL and they have different
118 * sizes. if in_pack_by_idx is allocated, oe_in_pack() returns
119 * the pack of an object using in_pack_idx field. If not,
120 * in_pack[] array is used the same way as in_pack_pos[]
121 */
122 struct packed_git **in_pack_by_idx;
123 struct packed_git **in_pack;
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124
125 uintmax_t oe_size_limit;
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126};
127
43fa44fa 128void prepare_packing_data(struct packing_data *pdata);
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129struct object_entry *packlist_alloc(struct packing_data *pdata,
130 const unsigned char *sha1,
131 uint32_t index_pos);
132
133struct object_entry *packlist_find(struct packing_data *pdata,
134 const unsigned char *sha1,
135 uint32_t *index_pos);
136
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137static inline uint32_t pack_name_hash(const char *name)
138{
139 uint32_t c, hash = 0;
140
141 if (!name)
142 return 0;
143
144 /*
145 * This effectively just creates a sortable number from the
146 * last sixteen non-whitespace characters. Last characters
147 * count "most", so things that end in ".c" sort together.
148 */
149 while ((c = *name++) != 0) {
150 if (isspace(c))
151 continue;
152 hash = (hash >> 2) + (c << 24);
153 }
154 return hash;
155}
156
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157static inline enum object_type oe_type(const struct object_entry *e)
158{
159 return e->type_valid ? e->type_ : OBJ_BAD;
160}
161
162static inline void oe_set_type(struct object_entry *e,
163 enum object_type type)
164{
165 if (type >= OBJ_ANY)
166 BUG("OBJ_ANY cannot be set in pack-objects code");
167
168 e->type_valid = type >= OBJ_NONE;
169 e->type_ = (unsigned)type;
170}
171
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172static inline unsigned int oe_in_pack_pos(const struct packing_data *pack,
173 const struct object_entry *e)
174{
175 return pack->in_pack_pos[e - pack->objects];
176}
177
178static inline void oe_set_in_pack_pos(const struct packing_data *pack,
179 const struct object_entry *e,
180 unsigned int pos)
181{
182 pack->in_pack_pos[e - pack->objects] = pos;
183}
184
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185static inline struct packed_git *oe_in_pack(const struct packing_data *pack,
186 const struct object_entry *e)
187{
188 if (pack->in_pack_by_idx)
189 return pack->in_pack_by_idx[e->in_pack_idx];
190 else
191 return pack->in_pack[e - pack->objects];
192}
193
194void oe_map_new_pack(struct packing_data *pack,
195 struct packed_git *p);
196static inline void oe_set_in_pack(struct packing_data *pack,
197 struct object_entry *e,
198 struct packed_git *p)
199{
200 if (!p->index)
201 oe_map_new_pack(pack, p);
202 if (pack->in_pack_by_idx)
203 e->in_pack_idx = p->index;
204 else
205 pack->in_pack[e - pack->objects] = p;
206}
207
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208static inline struct object_entry *oe_delta(
209 const struct packing_data *pack,
210 const struct object_entry *e)
211{
212 if (e->delta_idx)
213 return &pack->objects[e->delta_idx - 1];
214 return NULL;
215}
216
217static inline void oe_set_delta(struct packing_data *pack,
218 struct object_entry *e,
219 struct object_entry *delta)
220{
221 if (delta)
222 e->delta_idx = (delta - pack->objects) + 1;
223 else
224 e->delta_idx = 0;
225}
226
227static inline struct object_entry *oe_delta_child(
228 const struct packing_data *pack,
229 const struct object_entry *e)
230{
231 if (e->delta_child_idx)
232 return &pack->objects[e->delta_child_idx - 1];
233 return NULL;
234}
235
236static inline void oe_set_delta_child(struct packing_data *pack,
237 struct object_entry *e,
238 struct object_entry *delta)
239{
240 if (delta)
241 e->delta_child_idx = (delta - pack->objects) + 1;
242 else
243 e->delta_child_idx = 0;
244}
245
246static inline struct object_entry *oe_delta_sibling(
247 const struct packing_data *pack,
248 const struct object_entry *e)
249{
250 if (e->delta_sibling_idx)
251 return &pack->objects[e->delta_sibling_idx - 1];
252 return NULL;
253}
254
255static inline void oe_set_delta_sibling(struct packing_data *pack,
256 struct object_entry *e,
257 struct object_entry *delta)
258{
259 if (delta)
260 e->delta_sibling_idx = (delta - pack->objects) + 1;
261 else
262 e->delta_sibling_idx = 0;
263}
264
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265unsigned long oe_get_size_slow(struct packing_data *pack,
266 const struct object_entry *e);
267static inline unsigned long oe_size(struct packing_data *pack,
268 const struct object_entry *e)
269{
270 if (e->size_valid)
271 return e->size_;
272
273 return oe_get_size_slow(pack, e);
274}
275
276static inline int oe_size_less_than(struct packing_data *pack,
277 const struct object_entry *lhs,
278 unsigned long rhs)
279{
280 if (lhs->size_valid)
281 return lhs->size_ < rhs;
282 if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */
283 return 0;
284 return oe_get_size_slow(pack, lhs) < rhs;
285}
286
287static inline int oe_size_greater_than(struct packing_data *pack,
288 const struct object_entry *lhs,
289 unsigned long rhs)
290{
291 if (lhs->size_valid)
292 return lhs->size_ > rhs;
293 if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */
294 return 1;
295 return oe_get_size_slow(pack, lhs) > rhs;
296}
297
298static inline void oe_set_size(struct packing_data *pack,
299 struct object_entry *e,
300 unsigned long size)
301{
302 if (size < pack->oe_size_limit) {
303 e->size_ = size;
304 e->size_valid = 1;
305 } else {
306 e->size_valid = 0;
307 if (oe_get_size_slow(pack, e) != size)
308 BUG("'size' is supposed to be the object size!");
309 }
310}
311
2834bc27 312#endif