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1#ifndef PACK_OBJECTS_H
2#define PACK_OBJECTS_H
3
4#include "odb.h"
5#include "thread-utils.h"
6#include "pack.h"
7#include "packfile.h"
8
9struct repository;
10
11#define DEFAULT_DELTA_CACHE_SIZE (256 * 1024 * 1024)
12#define DEFAULT_DELTA_BASE_CACHE_LIMIT (96 * 1024 * 1024)
13
14#define OE_DFS_STATE_BITS 2
15#define OE_DEPTH_BITS 12
16#define OE_IN_PACK_BITS 10
17#define OE_Z_DELTA_BITS 20
18/*
19 * Note that oe_set_size() becomes expensive when the given size is
20 * above this limit. Don't lower it too much.
21 */
22#define OE_SIZE_BITS 31
23#define OE_DELTA_SIZE_BITS 23
24
25/*
26 * State flags for depth-first search used for analyzing delta cycles.
27 *
28 * The depth is measured in delta-links to the base (so if A is a delta
29 * against B, then A has a depth of 1, and B a depth of 0).
30 */
31enum dfs_state {
32 DFS_NONE = 0,
33 DFS_ACTIVE,
34 DFS_DONE,
35 DFS_NUM_STATES
36};
37
38/*
39 * The size of struct nearly determines pack-objects's memory
40 * consumption. This struct is packed tight for that reason. When you
41 * add or reorder something in this struct, think a bit about this.
42 *
43 * basic object info
44 * -----------------
45 * idx.oid is filled up before delta searching starts. idx.crc32 is
46 * only valid after the object is written out and will be used for
47 * generating the index. idx.offset will be both gradually set and
48 * used in writing phase (base objects get offset first, then deltas
49 * refer to them)
50 *
51 * "size" is the uncompressed object size. Compressed size of the raw
52 * data for an object in a pack is not stored anywhere but is computed
53 * and made available when reverse .idx is made. Note that when a
54 * delta is reused, "size" is the uncompressed _delta_ size, not the
55 * canonical one after the delta has been applied.
56 *
57 * "hash" contains a path name hash which is used for sorting the
58 * delta list and also during delta searching. Once prepare_pack()
59 * returns it's no longer needed.
60 *
61 * source pack info
62 * ----------------
63 * The (in_pack, in_pack_offset) tuple contains the location of the
64 * object in the source pack. in_pack_header_size allows quickly
65 * skipping the header and going straight to the zlib stream.
66 *
67 * "type" and "in_pack_type" both describe object type. in_pack_type
68 * may contain a delta type, while type is always the canonical type.
69 *
70 * deltas
71 * ------
72 * Delta links (delta, delta_child and delta_sibling) are created to
73 * reflect that delta graph from the source pack then updated or added
74 * during delta searching phase when we find better deltas.
75 *
76 * delta_child and delta_sibling are last needed in
77 * compute_write_order(). "delta" and "delta_size" must remain valid
78 * at object writing phase in case the delta is not cached.
79 *
80 * If a delta is cached in memory and is compressed, delta_data points
81 * to the data and z_delta_size contains the compressed size. If it's
82 * uncompressed [1], z_delta_size must be zero. delta_size is always
83 * the uncompressed size and must be valid even if the delta is not
84 * cached.
85 *
86 * [1] during try_delta phase we don't bother with compressing because
87 * the delta could be quickly replaced with a better one.
88 */
89struct object_entry {
90 struct pack_idx_entry idx;
91 void *delta_data; /* cached delta (uncompressed) */
92 off_t in_pack_offset;
93 uint32_t hash; /* name hint hash */
94 unsigned size_:OE_SIZE_BITS;
95 unsigned size_valid:1;
96 uint32_t delta_idx; /* delta base object */
97 uint32_t delta_child_idx; /* deltified objects who bases me */
98 uint32_t delta_sibling_idx; /* other deltified objects who
99 * uses the same base as me
100 */
101 unsigned delta_size_:OE_DELTA_SIZE_BITS; /* delta data size (uncompressed) */
102 unsigned delta_size_valid:1;
103 unsigned char in_pack_header_size;
104 unsigned in_pack_idx:OE_IN_PACK_BITS; /* already in pack */
105 unsigned z_delta_size:OE_Z_DELTA_BITS;
106 unsigned type_valid:1;
107 unsigned no_try_delta:1;
108 unsigned type_:TYPE_BITS;
109 unsigned in_pack_type:TYPE_BITS; /* could be delta */
110
111 unsigned preferred_base:1; /*
112 * we do not pack this, but is available
113 * to be used as the base object to delta
114 * objects against.
115 */
116 unsigned tagged:1; /* near the very tip of refs */
117 unsigned filled:1; /* assigned write-order */
118 unsigned dfs_state:OE_DFS_STATE_BITS;
119 unsigned depth:OE_DEPTH_BITS;
120 unsigned ext_base:1; /* delta_idx points outside packlist */
121};
122
123/**
124 * A packing region is a section of the packing_data.objects array
125 * as given by a starting index and a number of elements.
126 */
127struct packing_region {
128 size_t start;
129 size_t nr;
130};
131
132struct packing_data {
133 struct repository *repo;
134 struct object_entry *objects;
135 uint32_t nr_objects, nr_alloc;
136
137 struct packing_region *regions;
138 size_t nr_regions, nr_regions_alloc;
139
140 int32_t *index;
141 uint32_t index_size;
142
143 unsigned int *in_pack_pos;
144 unsigned long *delta_size;
145
146 /*
147 * Only one of these can be non-NULL and they have different
148 * sizes. if in_pack_by_idx is allocated, oe_in_pack() returns
149 * the pack of an object using in_pack_idx field. If not,
150 * in_pack[] array is used the same way as in_pack_pos[]
151 */
152 struct packed_git **in_pack_by_idx;
153 struct packed_git **in_pack;
154
155 /*
156 * During packing with multiple threads, protect the in-core
157 * object database from concurrent accesses.
158 */
159 pthread_mutex_t odb_lock;
160
161 /*
162 * This list contains entries for bases which we know the other side
163 * has (e.g., via reachability bitmaps), but which aren't in our
164 * "objects" list.
165 */
166 struct object_entry *ext_bases;
167 uint32_t nr_ext, alloc_ext;
168
169 uintmax_t oe_size_limit;
170 uintmax_t oe_delta_size_limit;
171
172 /* delta islands */
173 unsigned int *tree_depth;
174 unsigned char *layer;
175
176 /*
177 * Used when writing cruft packs.
178 *
179 * Object mtimes are stored in pack order when writing, but
180 * written out in lexicographic (index) order.
181 */
182 uint32_t *cruft_mtime;
183};
184
185void prepare_packing_data(struct repository *r, struct packing_data *pdata);
186void clear_packing_data(struct packing_data *pdata);
187
188/* Protect access to object database */
189static inline void packing_data_lock(struct packing_data *pdata)
190{
191 pthread_mutex_lock(&pdata->odb_lock);
192}
193static inline void packing_data_unlock(struct packing_data *pdata)
194{
195 pthread_mutex_unlock(&pdata->odb_lock);
196}
197
198struct object_entry *packlist_alloc(struct packing_data *pdata,
199 const struct object_id *oid);
200
201struct object_entry *packlist_find(struct packing_data *pdata,
202 const struct object_id *oid);
203
204static inline uint32_t pack_name_hash(const char *name)
205{
206 uint32_t c, hash = 0;
207
208 if (!name)
209 return 0;
210
211 /*
212 * This effectively just creates a sortable number from the
213 * last sixteen non-whitespace characters. Last characters
214 * count "most", so things that end in ".c" sort together.
215 */
216 while ((c = *name++) != 0) {
217 if (isspace(c))
218 continue;
219 hash = (hash >> 2) + (c << 24);
220 }
221 return hash;
222}
223
224static inline uint32_t pack_name_hash_v2(const unsigned char *name)
225{
226 uint32_t hash = 0, base = 0, c;
227
228 if (!name)
229 return 0;
230
231 while ((c = *name++)) {
232 if (isspace(c))
233 continue;
234 if (c == '/') {
235 base = (base >> 6) ^ hash;
236 hash = 0;
237 } else {
238 /*
239 * 'c' is only a single byte. Reverse it and move
240 * it to the top of the hash, moving the rest to
241 * less-significant bits.
242 */
243 c = (c & 0xF0) >> 4 | (c & 0x0F) << 4;
244 c = (c & 0xCC) >> 2 | (c & 0x33) << 2;
245 c = (c & 0xAA) >> 1 | (c & 0x55) << 1;
246 hash = (hash >> 2) + (c << 24);
247 }
248 }
249 return (base >> 6) ^ hash;
250}
251
252static inline enum object_type oe_type(const struct object_entry *e)
253{
254 return e->type_valid ? e->type_ : OBJ_BAD;
255}
256
257static inline void oe_set_type(struct object_entry *e,
258 enum object_type type)
259{
260 if (type >= OBJ_ANY)
261 BUG("OBJ_ANY cannot be set in pack-objects code");
262
263 e->type_valid = type >= OBJ_NONE;
264 e->type_ = (unsigned)type;
265}
266
267static inline unsigned int oe_in_pack_pos(const struct packing_data *pack,
268 const struct object_entry *e)
269{
270 return pack->in_pack_pos[e - pack->objects];
271}
272
273static inline void oe_set_in_pack_pos(const struct packing_data *pack,
274 const struct object_entry *e,
275 unsigned int pos)
276{
277 pack->in_pack_pos[e - pack->objects] = pos;
278}
279
280static inline struct packed_git *oe_in_pack(const struct packing_data *pack,
281 const struct object_entry *e)
282{
283 if (pack->in_pack_by_idx)
284 return pack->in_pack_by_idx[e->in_pack_idx];
285 else
286 return pack->in_pack[e - pack->objects];
287}
288
289void oe_map_new_pack(struct packing_data *pack);
290
291static inline void oe_set_in_pack(struct packing_data *pack,
292 struct object_entry *e,
293 struct packed_git *p)
294{
295 if (pack->in_pack_by_idx) {
296 if (p->index) {
297 e->in_pack_idx = p->index;
298 return;
299 }
300 /*
301 * We're accessing packs by index, but this pack doesn't have
302 * an index (e.g., because it was added since we created the
303 * in_pack_by_idx array). Bail to oe_map_new_pack(), which
304 * will convert us to using the full in_pack array, and then
305 * fall through to our in_pack handling.
306 */
307 oe_map_new_pack(pack);
308 }
309 pack->in_pack[e - pack->objects] = p;
310}
311
312void oe_set_delta_ext(struct packing_data *pack,
313 struct object_entry *e,
314 const struct object_id *oid);
315
316static inline unsigned int oe_tree_depth(struct packing_data *pack,
317 struct object_entry *e)
318{
319 if (!pack->tree_depth)
320 return 0;
321 return pack->tree_depth[e - pack->objects];
322}
323
324static inline void oe_set_layer(struct packing_data *pack,
325 struct object_entry *e,
326 unsigned char layer)
327{
328 if (!pack->layer)
329 CALLOC_ARRAY(pack->layer, pack->nr_alloc);
330 pack->layer[e - pack->objects] = layer;
331}
332
333static inline uint32_t oe_cruft_mtime(struct packing_data *pack,
334 struct object_entry *e)
335{
336 if (!pack->cruft_mtime)
337 return 0;
338 return pack->cruft_mtime[e - pack->objects];
339}
340
341static inline void oe_set_cruft_mtime(struct packing_data *pack,
342 struct object_entry *e,
343 uint32_t mtime)
344{
345 if (!pack->cruft_mtime)
346 CALLOC_ARRAY(pack->cruft_mtime, pack->nr_alloc);
347 pack->cruft_mtime[e - pack->objects] = mtime;
348}
349
350#endif