git: use COPY_ARRAY and MOVE_ARRAY in handle_alias()
[git/git.git] / pack-objects.h
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 struct repository;
9
10 #define DEFAULT_DELTA_CACHE_SIZE (256 * 1024 * 1024)
11
12 #define OE_DFS_STATE_BITS 2
13 #define OE_DEPTH_BITS 12
14 #define OE_IN_PACK_BITS 10
15 #define OE_Z_DELTA_BITS 20
16 /*
17 * Note that oe_set_size() becomes expensive when the given size is
18 * above this limit. Don't lower it too much.
19 */
20 #define OE_SIZE_BITS 31
21 #define OE_DELTA_SIZE_BITS 23
22
23 /*
24 * State flags for depth-first search used for analyzing delta cycles.
25 *
26 * The depth is measured in delta-links to the base (so if A is a delta
27 * against B, then A has a depth of 1, and B a depth of 0).
28 */
29 enum dfs_state {
30 DFS_NONE = 0,
31 DFS_ACTIVE,
32 DFS_DONE,
33 DFS_NUM_STATES
34 };
35
36 /*
37 * The size of struct nearly determines pack-objects's memory
38 * consumption. This struct is packed tight for that reason. When you
39 * add or reorder something in this struct, think a bit about this.
40 *
41 * basic object info
42 * -----------------
43 * idx.oid is filled up before delta searching starts. idx.crc32 is
44 * only valid after the object is written out and will be used for
45 * generating the index. idx.offset will be both gradually set and
46 * used in writing phase (base objects get offset first, then deltas
47 * refer to them)
48 *
49 * "size" is the uncompressed object size. Compressed size of the raw
50 * data for an object in a pack is not stored anywhere but is computed
51 * and made available when reverse .idx is made. Note that when a
52 * delta is reused, "size" is the uncompressed _delta_ size, not the
53 * canonical one after the delta has been applied.
54 *
55 * "hash" contains a path name hash which is used for sorting the
56 * delta list and also during delta searching. Once prepare_pack()
57 * returns it's no longer needed.
58 *
59 * source pack info
60 * ----------------
61 * The (in_pack, in_pack_offset) tuple contains the location of the
62 * object in the source pack. in_pack_header_size allows quickly
63 * skipping the header and going straight to the zlib stream.
64 *
65 * "type" and "in_pack_type" both describe object type. in_pack_type
66 * may contain a delta type, while type is always the canonical type.
67 *
68 * deltas
69 * ------
70 * Delta links (delta, delta_child and delta_sibling) are created to
71 * reflect that delta graph from the source pack then updated or added
72 * during delta searching phase when we find better deltas.
73 *
74 * delta_child and delta_sibling are last needed in
75 * compute_write_order(). "delta" and "delta_size" must remain valid
76 * at object writing phase in case the delta is not cached.
77 *
78 * If a delta is cached in memory and is compressed, delta_data points
79 * to the data and z_delta_size contains the compressed size. If it's
80 * uncompressed [1], z_delta_size must be zero. delta_size is always
81 * the uncompressed size and must be valid even if the delta is not
82 * cached.
83 *
84 * [1] during try_delta phase we don't bother with compressing because
85 * the delta could be quickly replaced with a better one.
86 */
87 struct object_entry {
88 struct pack_idx_entry idx;
89 void *delta_data; /* cached delta (uncompressed) */
90 off_t in_pack_offset;
91 uint32_t hash; /* name hint hash */
92 unsigned size_:OE_SIZE_BITS;
93 unsigned size_valid:1;
94 uint32_t delta_idx; /* delta base object */
95 uint32_t delta_child_idx; /* deltified objects who bases me */
96 uint32_t delta_sibling_idx; /* other deltified objects who
97 * uses the same base as me
98 */
99 unsigned delta_size_:OE_DELTA_SIZE_BITS; /* delta data size (uncompressed) */
100 unsigned delta_size_valid:1;
101 unsigned char in_pack_header_size;
102 unsigned in_pack_idx:OE_IN_PACK_BITS; /* already in pack */
103 unsigned z_delta_size:OE_Z_DELTA_BITS;
104 unsigned type_valid:1;
105 unsigned no_try_delta:1;
106 unsigned type_:TYPE_BITS;
107 unsigned in_pack_type:TYPE_BITS; /* could be delta */
108
109 unsigned preferred_base:1; /*
110 * we do not pack this, but is available
111 * to be used as the base object to delta
112 * objects against.
113 */
114 unsigned tagged:1; /* near the very tip of refs */
115 unsigned filled:1; /* assigned write-order */
116 unsigned dfs_state:OE_DFS_STATE_BITS;
117 unsigned depth:OE_DEPTH_BITS;
118 unsigned ext_base:1; /* delta_idx points outside packlist */
119
120 /*
121 * pahole results on 64-bit linux (gcc and clang)
122 *
123 * size: 80, bit_padding: 9 bits
124 *
125 * and on 32-bit (gcc)
126 *
127 * size: 76, bit_padding: 9 bits
128 */
129 };
130
131 struct packing_data {
132 struct repository *repo;
133 struct object_entry *objects;
134 uint32_t nr_objects, nr_alloc;
135
136 int32_t *index;
137 uint32_t index_size;
138
139 unsigned int *in_pack_pos;
140 unsigned long *delta_size;
141
142 /*
143 * Only one of these can be non-NULL and they have different
144 * sizes. if in_pack_by_idx is allocated, oe_in_pack() returns
145 * the pack of an object using in_pack_idx field. If not,
146 * in_pack[] array is used the same way as in_pack_pos[]
147 */
148 struct packed_git **in_pack_by_idx;
149 struct packed_git **in_pack;
150
151 /*
152 * During packing with multiple threads, protect the in-core
153 * object database from concurrent accesses.
154 */
155 pthread_mutex_t odb_lock;
156
157 /*
158 * This list contains entries for bases which we know the other side
159 * has (e.g., via reachability bitmaps), but which aren't in our
160 * "objects" list.
161 */
162 struct object_entry *ext_bases;
163 uint32_t nr_ext, alloc_ext;
164
165 uintmax_t oe_size_limit;
166 uintmax_t oe_delta_size_limit;
167
168 /* delta islands */
169 unsigned int *tree_depth;
170 unsigned char *layer;
171 };
172
173 void prepare_packing_data(struct repository *r, struct packing_data *pdata);
174
175 /* Protect access to object database */
176 static inline void packing_data_lock(struct packing_data *pdata)
177 {
178 pthread_mutex_lock(&pdata->odb_lock);
179 }
180 static inline void packing_data_unlock(struct packing_data *pdata)
181 {
182 pthread_mutex_unlock(&pdata->odb_lock);
183 }
184
185 struct object_entry *packlist_alloc(struct packing_data *pdata,
186 const unsigned char *sha1,
187 uint32_t index_pos);
188
189 struct object_entry *packlist_find(struct packing_data *pdata,
190 const struct object_id *oid,
191 uint32_t *index_pos);
192
193 static inline uint32_t pack_name_hash(const char *name)
194 {
195 uint32_t c, hash = 0;
196
197 if (!name)
198 return 0;
199
200 /*
201 * This effectively just creates a sortable number from the
202 * last sixteen non-whitespace characters. Last characters
203 * count "most", so things that end in ".c" sort together.
204 */
205 while ((c = *name++) != 0) {
206 if (isspace(c))
207 continue;
208 hash = (hash >> 2) + (c << 24);
209 }
210 return hash;
211 }
212
213 static inline enum object_type oe_type(const struct object_entry *e)
214 {
215 return e->type_valid ? e->type_ : OBJ_BAD;
216 }
217
218 static inline void oe_set_type(struct object_entry *e,
219 enum object_type type)
220 {
221 if (type >= OBJ_ANY)
222 BUG("OBJ_ANY cannot be set in pack-objects code");
223
224 e->type_valid = type >= OBJ_NONE;
225 e->type_ = (unsigned)type;
226 }
227
228 static inline unsigned int oe_in_pack_pos(const struct packing_data *pack,
229 const struct object_entry *e)
230 {
231 return pack->in_pack_pos[e - pack->objects];
232 }
233
234 static inline void oe_set_in_pack_pos(const struct packing_data *pack,
235 const struct object_entry *e,
236 unsigned int pos)
237 {
238 pack->in_pack_pos[e - pack->objects] = pos;
239 }
240
241 static inline struct packed_git *oe_in_pack(const struct packing_data *pack,
242 const struct object_entry *e)
243 {
244 if (pack->in_pack_by_idx)
245 return pack->in_pack_by_idx[e->in_pack_idx];
246 else
247 return pack->in_pack[e - pack->objects];
248 }
249
250 void oe_map_new_pack(struct packing_data *pack);
251
252 static inline void oe_set_in_pack(struct packing_data *pack,
253 struct object_entry *e,
254 struct packed_git *p)
255 {
256 if (!p->index)
257 oe_map_new_pack(pack);
258 if (pack->in_pack_by_idx)
259 e->in_pack_idx = p->index;
260 else
261 pack->in_pack[e - pack->objects] = p;
262 }
263
264 static inline struct object_entry *oe_delta(
265 const struct packing_data *pack,
266 const struct object_entry *e)
267 {
268 if (!e->delta_idx)
269 return NULL;
270 if (e->ext_base)
271 return &pack->ext_bases[e->delta_idx - 1];
272 else
273 return &pack->objects[e->delta_idx - 1];
274 }
275
276 static inline void oe_set_delta(struct packing_data *pack,
277 struct object_entry *e,
278 struct object_entry *delta)
279 {
280 if (delta)
281 e->delta_idx = (delta - pack->objects) + 1;
282 else
283 e->delta_idx = 0;
284 }
285
286 void oe_set_delta_ext(struct packing_data *pack,
287 struct object_entry *e,
288 const unsigned char *sha1);
289
290 static inline struct object_entry *oe_delta_child(
291 const struct packing_data *pack,
292 const struct object_entry *e)
293 {
294 if (e->delta_child_idx)
295 return &pack->objects[e->delta_child_idx - 1];
296 return NULL;
297 }
298
299 static inline void oe_set_delta_child(struct packing_data *pack,
300 struct object_entry *e,
301 struct object_entry *delta)
302 {
303 if (delta)
304 e->delta_child_idx = (delta - pack->objects) + 1;
305 else
306 e->delta_child_idx = 0;
307 }
308
309 static inline struct object_entry *oe_delta_sibling(
310 const struct packing_data *pack,
311 const struct object_entry *e)
312 {
313 if (e->delta_sibling_idx)
314 return &pack->objects[e->delta_sibling_idx - 1];
315 return NULL;
316 }
317
318 static inline void oe_set_delta_sibling(struct packing_data *pack,
319 struct object_entry *e,
320 struct object_entry *delta)
321 {
322 if (delta)
323 e->delta_sibling_idx = (delta - pack->objects) + 1;
324 else
325 e->delta_sibling_idx = 0;
326 }
327
328 unsigned long oe_get_size_slow(struct packing_data *pack,
329 const struct object_entry *e);
330 static inline unsigned long oe_size(struct packing_data *pack,
331 const struct object_entry *e)
332 {
333 if (e->size_valid)
334 return e->size_;
335
336 return oe_get_size_slow(pack, e);
337 }
338
339 static inline int oe_size_less_than(struct packing_data *pack,
340 const struct object_entry *lhs,
341 unsigned long rhs)
342 {
343 if (lhs->size_valid)
344 return lhs->size_ < rhs;
345 if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */
346 return 0;
347 return oe_get_size_slow(pack, lhs) < rhs;
348 }
349
350 static inline int oe_size_greater_than(struct packing_data *pack,
351 const struct object_entry *lhs,
352 unsigned long rhs)
353 {
354 if (lhs->size_valid)
355 return lhs->size_ > rhs;
356 if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */
357 return 1;
358 return oe_get_size_slow(pack, lhs) > rhs;
359 }
360
361 static inline void oe_set_size(struct packing_data *pack,
362 struct object_entry *e,
363 unsigned long size)
364 {
365 if (size < pack->oe_size_limit) {
366 e->size_ = size;
367 e->size_valid = 1;
368 } else {
369 e->size_valid = 0;
370 if (oe_get_size_slow(pack, e) != size)
371 BUG("'size' is supposed to be the object size!");
372 }
373 }
374
375 static inline unsigned long oe_delta_size(struct packing_data *pack,
376 const struct object_entry *e)
377 {
378 if (e->delta_size_valid)
379 return e->delta_size_;
380
381 /*
382 * pack->delta_size[] can't be NULL because oe_set_delta_size()
383 * must have been called when a new delta is saved with
384 * oe_set_delta().
385 * If oe_delta() returns NULL (i.e. default state, which means
386 * delta_size_valid is also false), then the caller must never
387 * call oe_delta_size().
388 */
389 return pack->delta_size[e - pack->objects];
390 }
391
392 static inline void oe_set_delta_size(struct packing_data *pack,
393 struct object_entry *e,
394 unsigned long size)
395 {
396 if (size < pack->oe_delta_size_limit) {
397 e->delta_size_ = size;
398 e->delta_size_valid = 1;
399 } else {
400 packing_data_lock(pack);
401 if (!pack->delta_size)
402 ALLOC_ARRAY(pack->delta_size, pack->nr_alloc);
403 packing_data_unlock(pack);
404
405 pack->delta_size[e - pack->objects] = size;
406 e->delta_size_valid = 0;
407 }
408 }
409
410 static inline unsigned int oe_tree_depth(struct packing_data *pack,
411 struct object_entry *e)
412 {
413 if (!pack->tree_depth)
414 return 0;
415 return pack->tree_depth[e - pack->objects];
416 }
417
418 static inline void oe_set_tree_depth(struct packing_data *pack,
419 struct object_entry *e,
420 unsigned int tree_depth)
421 {
422 if (!pack->tree_depth)
423 CALLOC_ARRAY(pack->tree_depth, pack->nr_alloc);
424 pack->tree_depth[e - pack->objects] = tree_depth;
425 }
426
427 static inline unsigned char oe_layer(struct packing_data *pack,
428 struct object_entry *e)
429 {
430 if (!pack->layer)
431 return 0;
432 return pack->layer[e - pack->objects];
433 }
434
435 static inline void oe_set_layer(struct packing_data *pack,
436 struct object_entry *e,
437 unsigned char layer)
438 {
439 if (!pack->layer)
440 CALLOC_ARRAY(pack->layer, pack->nr_alloc);
441 pack->layer[e - pack->objects] = layer;
442 }
443
444 #endif