summaryrefslogtreecommitdiff
path: root/pack-objects.h
blob: 393b9db546433d71de6f821a58d2a58a9ebc5ecb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
#ifndef PACK_OBJECTS_H
#define PACK_OBJECTS_H
 
#include "object-store.h"
#include "thread-utils.h"
#include "pack.h"
 
struct repository;
 
#define DEFAULT_DELTA_CACHE_SIZE (256 * 1024 * 1024)
 
#define OE_DFS_STATE_BITS	2
#define OE_DEPTH_BITS		12
#define OE_IN_PACK_BITS		10
#define OE_Z_DELTA_BITS		20
/*
 * Note that oe_set_size() becomes expensive when the given size is
 * above this limit. Don't lower it too much.
 */
#define OE_SIZE_BITS		31
#define OE_DELTA_SIZE_BITS	23
 
/*
 * State flags for depth-first search used for analyzing delta cycles.
 *
 * The depth is measured in delta-links to the base (so if A is a delta
 * against B, then A has a depth of 1, and B a depth of 0).
 */
enum dfs_state {
	DFS_NONE = 0,
	DFS_ACTIVE,
	DFS_DONE,
	DFS_NUM_STATES
};
 
/*
 * The size of struct nearly determines pack-objects's memory
 * consumption. This struct is packed tight for that reason. When you
 * add or reorder something in this struct, think a bit about this.
 *
 * basic object info
 * -----------------
 * idx.oid is filled up before delta searching starts. idx.crc32 is
 * only valid after the object is written out and will be used for
 * generating the index. idx.offset will be both gradually set and
 * used in writing phase (base objects get offset first, then deltas
 * refer to them)
 *
 * "size" is the uncompressed object size. Compressed size of the raw
 * data for an object in a pack is not stored anywhere but is computed
 * and made available when reverse .idx is made. Note that when a
 * delta is reused, "size" is the uncompressed _delta_ size, not the
 * canonical one after the delta has been applied.
 *
 * "hash" contains a path name hash which is used for sorting the
 * delta list and also during delta searching. Once prepare_pack()
 * returns it's no longer needed.
 *
 * source pack info
 * ----------------
 * The (in_pack, in_pack_offset) tuple contains the location of the
 * object in the source pack. in_pack_header_size allows quickly
 * skipping the header and going straight to the zlib stream.
 *
 * "type" and "in_pack_type" both describe object type. in_pack_type
 * may contain a delta type, while type is always the canonical type.
 *
 * deltas
 * ------
 * Delta links (delta, delta_child and delta_sibling) are created to
 * reflect that delta graph from the source pack then updated or added
 * during delta searching phase when we find better deltas.
 *
 * delta_child and delta_sibling are last needed in
 * compute_write_order(). "delta" and "delta_size" must remain valid
 * at object writing phase in case the delta is not cached.
 *
 * If a delta is cached in memory and is compressed, delta_data points
 * to the data and z_delta_size contains the compressed size. If it's
 * uncompressed [1], z_delta_size must be zero. delta_size is always
 * the uncompressed size and must be valid even if the delta is not
 * cached.
 *
 * [1] during try_delta phase we don't bother with compressing because
 * the delta could be quickly replaced with a better one.
 */
struct object_entry {
	struct pack_idx_entry idx;
	void *delta_data;	/* cached delta (uncompressed) */
	off_t in_pack_offset;
	uint32_t hash;			/* name hint hash */
	unsigned size_:OE_SIZE_BITS;
	unsigned size_valid:1;
	uint32_t delta_idx;	/* delta base object */
	uint32_t delta_child_idx; /* deltified objects who bases me */
	uint32_t delta_sibling_idx; /* other deltified objects who
				     * uses the same base as me
				     */
	unsigned delta_size_:OE_DELTA_SIZE_BITS; /* delta data size (uncompressed) */
	unsigned delta_size_valid:1;
	unsigned char in_pack_header_size;
	unsigned in_pack_idx:OE_IN_PACK_BITS;	/* already in pack */
	unsigned z_delta_size:OE_Z_DELTA_BITS;
	unsigned type_valid:1;
	unsigned no_try_delta:1;
	unsigned type_:TYPE_BITS;
	unsigned in_pack_type:TYPE_BITS; /* could be delta */
 
	unsigned preferred_base:1; /*
				    * we do not pack this, but is available
				    * to be used as the base object to delta
				    * objects against.
				    */
	unsigned tagged:1; /* near the very tip of refs */
	unsigned filled:1; /* assigned write-order */
	unsigned dfs_state:OE_DFS_STATE_BITS;
	unsigned depth:OE_DEPTH_BITS;
	unsigned ext_base:1; /* delta_idx points outside packlist */
 
	/*
	 * pahole results on 64-bit linux (gcc and clang)
	 *
	 *   size: 80, bit_padding: 9 bits
	 *
	 * and on 32-bit (gcc)
	 *
	 *   size: 76, bit_padding: 9 bits
	 */
};
 
struct packing_data {
	struct repository *repo;
	struct object_entry *objects;
	uint32_t nr_objects, nr_alloc;
 
	int32_t *index;
	uint32_t index_size;
 
	unsigned int *in_pack_pos;
	unsigned long *delta_size;
 
	/*
	 * Only one of these can be non-NULL and they have different
	 * sizes. if in_pack_by_idx is allocated, oe_in_pack() returns
	 * the pack of an object using in_pack_idx field. If not,
	 * in_pack[] array is used the same way as in_pack_pos[]
	 */
	struct packed_git **in_pack_by_idx;
	struct packed_git **in_pack;
 
	/*
	 * During packing with multiple threads, protect the in-core
	 * object database from concurrent accesses.
	 */
	pthread_mutex_t odb_lock;
 
	/*
	 * This list contains entries for bases which we know the other side
	 * has (e.g., via reachability bitmaps), but which aren't in our
	 * "objects" list.
	 */
	struct object_entry *ext_bases;
	uint32_t nr_ext, alloc_ext;
 
	uintmax_t oe_size_limit;
	uintmax_t oe_delta_size_limit;
 
	/* delta islands */
	unsigned int *tree_depth;
	unsigned char *layer;
 
	/*
	 * Used when writing cruft packs.
	 *
	 * Object mtimes are stored in pack order when writing, but
	 * written out in lexicographic (index) order.
	 */
	uint32_t *cruft_mtime;
};
 
void prepare_packing_data(struct repository *r, struct packing_data *pdata);
 
/* Protect access to object database */
static inline void packing_data_lock(struct packing_data *pdata)
{
	pthread_mutex_lock(&pdata->odb_lock);
}
static inline void packing_data_unlock(struct packing_data *pdata)
{
	pthread_mutex_unlock(&pdata->odb_lock);
}
 
struct object_entry *packlist_alloc(struct packing_data *pdata,
				    const struct object_id *oid);
 
struct object_entry *packlist_find(struct packing_data *pdata,
				   const struct object_id *oid);
 
static inline uint32_t pack_name_hash(const char *name)
{
	uint32_t c, hash = 0;
 
	if (!name)
		return 0;
 
	/*
	 * This effectively just creates a sortable number from the
	 * last sixteen non-whitespace characters. Last characters
	 * count "most", so things that end in ".c" sort together.
	 */
	while ((c = *name++) != 0) {
		if (isspace(c))
			continue;
		hash = (hash >> 2) + (c << 24);
	}
	return hash;
}
 
static inline enum object_type oe_type(const struct object_entry *e)
{
	return e->type_valid ? e->type_ : OBJ_BAD;
}
 
static inline void oe_set_type(struct object_entry *e,
			       enum object_type type)
{
	if (type >= OBJ_ANY)
		BUG("OBJ_ANY cannot be set in pack-objects code");
 
	e->type_valid = type >= OBJ_NONE;
	e->type_ = (unsigned)type;
}
 
static inline unsigned int oe_in_pack_pos(const struct packing_data *pack,
					  const struct object_entry *e)
{
	return pack->in_pack_pos[e - pack->objects];
}
 
static inline void oe_set_in_pack_pos(const struct packing_data *pack,
				      const struct object_entry *e,
				      unsigned int pos)
{
	pack->in_pack_pos[e - pack->objects] = pos;
}
 
static inline struct packed_git *oe_in_pack(const struct packing_data *pack,
					    const struct object_entry *e)
{
	if (pack->in_pack_by_idx)
		return pack->in_pack_by_idx[e->in_pack_idx];
	else
		return pack->in_pack[e - pack->objects];
}
 
void oe_map_new_pack(struct packing_data *pack);
 
static inline void oe_set_in_pack(struct packing_data *pack,
				  struct object_entry *e,
				  struct packed_git *p)
{
	if (pack->in_pack_by_idx) {
		if (p->index) {
			e->in_pack_idx = p->index;
			return;
		}
		/*
		 * We're accessing packs by index, but this pack doesn't have
		 * an index (e.g., because it was added since we created the
		 * in_pack_by_idx array). Bail to oe_map_new_pack(), which
		 * will convert us to using the full in_pack array, and then
		 * fall through to our in_pack handling.
		 */
		oe_map_new_pack(pack);
	}
	pack->in_pack[e - pack->objects] = p;
}
 
void oe_set_delta_ext(struct packing_data *pack,
		      struct object_entry *e,
		      const struct object_id *oid);
 
static inline unsigned int oe_tree_depth(struct packing_data *pack,
					 struct object_entry *e)
{
	if (!pack->tree_depth)
		return 0;
	return pack->tree_depth[e - pack->objects];
}
 
static inline void oe_set_layer(struct packing_data *pack,
				struct object_entry *e,
				unsigned char layer)
{
	if (!pack->layer)
		CALLOC_ARRAY(pack->layer, pack->nr_alloc);
	pack->layer[e - pack->objects] = layer;
}
 
static inline uint32_t oe_cruft_mtime(struct packing_data *pack,
				      struct object_entry *e)
{
	if (!pack->cruft_mtime)
		return 0;
	return pack->cruft_mtime[e - pack->objects];
}
 
static inline void oe_set_cruft_mtime(struct packing_data *pack,
				      struct object_entry *e,
				      uint32_t mtime)
{
	if (!pack->cruft_mtime)
		CALLOC_ARRAY(pack->cruft_mtime, pack->nr_alloc);
	pack->cruft_mtime[e - pack->objects] = mtime;
}
 
#endif