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1#ifndef PACK_OBJECTS_H
2#define PACK_OBJECTS_H
3
4#include "object-store.h"
5#include "thread-utils.h"
6#include "pack.h"
7
8#define DEFAULT_DELTA_CACHE_SIZE (256 * 1024 * 1024)
9
10#define OE_DFS_STATE_BITS 2
11#define OE_DEPTH_BITS 12
12#define OE_IN_PACK_BITS 10
13#define OE_Z_DELTA_BITS 20
14/*
15 * Note that oe_set_size() becomes expensive when the given size is
16 * above this limit. Don't lower it too much.
17 */
18#define OE_SIZE_BITS 31
19#define OE_DELTA_SIZE_BITS 23
20
21/*
22 * State flags for depth-first search used for analyzing delta cycles.
23 *
24 * The depth is measured in delta-links to the base (so if A is a delta
25 * against B, then A has a depth of 1, and B a depth of 0).
26 */
27enum dfs_state {
28 DFS_NONE = 0,
29 DFS_ACTIVE,
30 DFS_DONE,
31 DFS_NUM_STATES
32};
33
34/*
35 * The size of struct nearly determines pack-objects's memory
36 * consumption. This struct is packed tight for that reason. When you
37 * add or reorder something in this struct, think a bit about this.
38 *
39 * basic object info
40 * -----------------
41 * idx.oid is filled up before delta searching starts. idx.crc32 is
42 * only valid after the object is written out and will be used for
43 * generating the index. idx.offset will be both gradually set and
44 * used in writing phase (base objects get offset first, then deltas
45 * refer to them)
46 *
47 * "size" is the uncompressed object size. Compressed size of the raw
48 * data for an object in a pack is not stored anywhere but is computed
49 * and made available when reverse .idx is made. Note that when a
50 * delta is reused, "size" is the uncompressed _delta_ size, not the
51 * canonical one after the delta has been applied.
52 *
53 * "hash" contains a path name hash which is used for sorting the
54 * delta list and also during delta searching. Once prepare_pack()
55 * returns it's no longer needed.
56 *
57 * source pack info
58 * ----------------
59 * The (in_pack, in_pack_offset) tuple contains the location of the
60 * object in the source pack. in_pack_header_size allows quickly
61 * skipping the header and going straight to the zlib stream.
62 *
63 * "type" and "in_pack_type" both describe object type. in_pack_type
64 * may contain a delta type, while type is always the canonical type.
65 *
66 * deltas
67 * ------
68 * Delta links (delta, delta_child and delta_sibling) are created to
69 * reflect that delta graph from the source pack then updated or added
70 * during delta searching phase when we find better deltas.
71 *
72 * delta_child and delta_sibling are last needed in
73 * compute_write_order(). "delta" and "delta_size" must remain valid
74 * at object writing phase in case the delta is not cached.
75 *
76 * If a delta is cached in memory and is compressed, delta_data points
77 * to the data and z_delta_size contains the compressed size. If it's
78 * uncompressed [1], z_delta_size must be zero. delta_size is always
79 * the uncompressed size and must be valid even if the delta is not
80 * cached.
81 *
82 * [1] during try_delta phase we don't bother with compressing because
83 * the delta could be quickly replaced with a better one.
84 */
85struct object_entry {
86 struct pack_idx_entry idx;
87 void *delta_data; /* cached delta (uncompressed) */
88 off_t in_pack_offset;
89 uint32_t hash; /* name hint hash */
90 unsigned size_:OE_SIZE_BITS;
91 unsigned size_valid:1;
92 uint32_t delta_idx; /* delta base object */
93 uint32_t delta_child_idx; /* deltified objects who bases me */
94 uint32_t delta_sibling_idx; /* other deltified objects who
95 * uses the same base as me
96 */
97 unsigned delta_size_:OE_DELTA_SIZE_BITS; /* delta data size (uncompressed) */
98 unsigned delta_size_valid:1;
99 unsigned char in_pack_header_size;
100 unsigned in_pack_idx:OE_IN_PACK_BITS; /* already in pack */
101 unsigned z_delta_size:OE_Z_DELTA_BITS;
102 unsigned type_valid:1;
103 unsigned no_try_delta:1;
104 unsigned type_:TYPE_BITS;
105 unsigned in_pack_type:TYPE_BITS; /* could be delta */
106 unsigned preferred_base:1; /*
107 * we do not pack this, but is available
108 * to be used as the base object to delta
109 * objects against.
110 */
111 unsigned tagged:1; /* near the very tip of refs */
112 unsigned filled:1; /* assigned write-order */
113 unsigned dfs_state:OE_DFS_STATE_BITS;
114 unsigned depth:OE_DEPTH_BITS;
115
116 /*
117 * pahole results on 64-bit linux (gcc and clang)
118 *
119 * size: 80, bit_padding: 9 bits
120 *
121 * and on 32-bit (gcc)
122 *
123 * size: 76, bit_padding: 9 bits
124 */
125};
126
127struct packing_data {
128 struct object_entry *objects;
129 uint32_t nr_objects, nr_alloc;
130
131 int32_t *index;
132 uint32_t index_size;
133
134 unsigned int *in_pack_pos;
135 unsigned long *delta_size;
136
137 /*
138 * Only one of these can be non-NULL and they have different
139 * sizes. if in_pack_by_idx is allocated, oe_in_pack() returns
140 * the pack of an object using in_pack_idx field. If not,
141 * in_pack[] array is used the same way as in_pack_pos[]
142 */
143 struct packed_git **in_pack_by_idx;
144 struct packed_git **in_pack;
145
146#ifndef NO_PTHREADS
147 pthread_mutex_t lock;
148#endif
149
150 uintmax_t oe_size_limit;
151 uintmax_t oe_delta_size_limit;
152};
153
154void prepare_packing_data(struct packing_data *pdata);
155
156static inline void packing_data_lock(struct packing_data *pdata)
157{
158#ifndef NO_PTHREADS
159 pthread_mutex_lock(&pdata->lock);
160#endif
161}
162static inline void packing_data_unlock(struct packing_data *pdata)
163{
164#ifndef NO_PTHREADS
165 pthread_mutex_unlock(&pdata->lock);
166#endif
167}
168
169struct object_entry *packlist_alloc(struct packing_data *pdata,
170 const unsigned char *sha1,
171 uint32_t index_pos);
172
173struct object_entry *packlist_find(struct packing_data *pdata,
174 const unsigned char *sha1,
175 uint32_t *index_pos);
176
177static inline uint32_t pack_name_hash(const char *name)
178{
179 uint32_t c, hash = 0;
180
181 if (!name)
182 return 0;
183
184 /*
185 * This effectively just creates a sortable number from the
186 * last sixteen non-whitespace characters. Last characters
187 * count "most", so things that end in ".c" sort together.
188 */
189 while ((c = *name++) != 0) {
190 if (isspace(c))
191 continue;
192 hash = (hash >> 2) + (c << 24);
193 }
194 return hash;
195}
196
197static inline enum object_type oe_type(const struct object_entry *e)
198{
199 return e->type_valid ? e->type_ : OBJ_BAD;
200}
201
202static inline void oe_set_type(struct object_entry *e,
203 enum object_type type)
204{
205 if (type >= OBJ_ANY)
206 BUG("OBJ_ANY cannot be set in pack-objects code");
207
208 e->type_valid = type >= OBJ_NONE;
209 e->type_ = (unsigned)type;
210}
211
212static inline unsigned int oe_in_pack_pos(const struct packing_data *pack,
213 const struct object_entry *e)
214{
215 return pack->in_pack_pos[e - pack->objects];
216}
217
218static inline void oe_set_in_pack_pos(const struct packing_data *pack,
219 const struct object_entry *e,
220 unsigned int pos)
221{
222 pack->in_pack_pos[e - pack->objects] = pos;
223}
224
225static inline struct packed_git *oe_in_pack(const struct packing_data *pack,
226 const struct object_entry *e)
227{
228 if (pack->in_pack_by_idx)
229 return pack->in_pack_by_idx[e->in_pack_idx];
230 else
231 return pack->in_pack[e - pack->objects];
232}
233
234void oe_map_new_pack(struct packing_data *pack,
235 struct packed_git *p);
236static inline void oe_set_in_pack(struct packing_data *pack,
237 struct object_entry *e,
238 struct packed_git *p)
239{
240 if (!p->index)
241 oe_map_new_pack(pack, p);
242 if (pack->in_pack_by_idx)
243 e->in_pack_idx = p->index;
244 else
245 pack->in_pack[e - pack->objects] = p;
246}
247
248static inline struct object_entry *oe_delta(
249 const struct packing_data *pack,
250 const struct object_entry *e)
251{
252 if (e->delta_idx)
253 return &pack->objects[e->delta_idx - 1];
254 return NULL;
255}
256
257static inline void oe_set_delta(struct packing_data *pack,
258 struct object_entry *e,
259 struct object_entry *delta)
260{
261 if (delta)
262 e->delta_idx = (delta - pack->objects) + 1;
263 else
264 e->delta_idx = 0;
265}
266
267static inline struct object_entry *oe_delta_child(
268 const struct packing_data *pack,
269 const struct object_entry *e)
270{
271 if (e->delta_child_idx)
272 return &pack->objects[e->delta_child_idx - 1];
273 return NULL;
274}
275
276static inline void oe_set_delta_child(struct packing_data *pack,
277 struct object_entry *e,
278 struct object_entry *delta)
279{
280 if (delta)
281 e->delta_child_idx = (delta - pack->objects) + 1;
282 else
283 e->delta_child_idx = 0;
284}
285
286static inline struct object_entry *oe_delta_sibling(
287 const struct packing_data *pack,
288 const struct object_entry *e)
289{
290 if (e->delta_sibling_idx)
291 return &pack->objects[e->delta_sibling_idx - 1];
292 return NULL;
293}
294
295static inline void oe_set_delta_sibling(struct packing_data *pack,
296 struct object_entry *e,
297 struct object_entry *delta)
298{
299 if (delta)
300 e->delta_sibling_idx = (delta - pack->objects) + 1;
301 else
302 e->delta_sibling_idx = 0;
303}
304
305unsigned long oe_get_size_slow(struct packing_data *pack,
306 const struct object_entry *e);
307static inline unsigned long oe_size(struct packing_data *pack,
308 const struct object_entry *e)
309{
310 if (e->size_valid)
311 return e->size_;
312
313 return oe_get_size_slow(pack, e);
314}
315
316static inline int oe_size_less_than(struct packing_data *pack,
317 const struct object_entry *lhs,
318 unsigned long rhs)
319{
320 if (lhs->size_valid)
321 return lhs->size_ < rhs;
322 if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */
323 return 0;
324 return oe_get_size_slow(pack, lhs) < rhs;
325}
326
327static inline int oe_size_greater_than(struct packing_data *pack,
328 const struct object_entry *lhs,
329 unsigned long rhs)
330{
331 if (lhs->size_valid)
332 return lhs->size_ > rhs;
333 if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */
334 return 1;
335 return oe_get_size_slow(pack, lhs) > rhs;
336}
337
338static inline void oe_set_size(struct packing_data *pack,
339 struct object_entry *e,
340 unsigned long size)
341{
342 if (size < pack->oe_size_limit) {
343 e->size_ = size;
344 e->size_valid = 1;
345 } else {
346 e->size_valid = 0;
347 if (oe_get_size_slow(pack, e) != size)
348 BUG("'size' is supposed to be the object size!");
349 }
350}
351
352static inline unsigned long oe_delta_size(struct packing_data *pack,
353 const struct object_entry *e)
354{
355 if (e->delta_size_valid)
356 return e->delta_size_;
357
358 /*
359 * pack->detla_size[] can't be NULL because oe_set_delta_size()
360 * must have been called when a new delta is saved with
361 * oe_set_delta().
362 * If oe_delta() returns NULL (i.e. default state, which means
363 * delta_size_valid is also false), then the caller must never
364 * call oe_delta_size().
365 */
366 return pack->delta_size[e - pack->objects];
367}
368
369static inline void oe_set_delta_size(struct packing_data *pack,
370 struct object_entry *e,
371 unsigned long size)
372{
373 if (size < pack->oe_delta_size_limit) {
374 e->delta_size_ = size;
375 e->delta_size_valid = 1;
376 } else {
377 packing_data_lock(pack);
378 if (!pack->delta_size)
379 ALLOC_ARRAY(pack->delta_size, pack->nr_alloc);
380 packing_data_unlock(pack);
381
382 pack->delta_size[e - pack->objects] = size;
383 e->delta_size_valid = 0;
384 }
385}
386
387#endif