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Commit | Line | Data |
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f52207a4 GS |
1 | #include "git-compat-util.h" |
2 | #include "bloom.h" | |
ed591feb GS |
3 | #include "diff.h" |
4 | #include "diffcore.h" | |
5 | #include "revision.h" | |
6 | #include "hashmap.h" | |
1217c03e GS |
7 | #include "commit-graph.h" |
8 | #include "commit.h" | |
ed591feb GS |
9 | |
10 | define_commit_slab(bloom_filter_slab, struct bloom_filter); | |
11 | ||
12 | struct bloom_filter_slab bloom_filters; | |
13 | ||
14 | struct pathmap_hash_entry { | |
15 | struct hashmap_entry entry; | |
16 | const char path[FLEX_ARRAY]; | |
17 | }; | |
f52207a4 GS |
18 | |
19 | static uint32_t rotate_left(uint32_t value, int32_t count) | |
20 | { | |
21 | uint32_t mask = 8 * sizeof(uint32_t) - 1; | |
22 | count &= mask; | |
23 | return ((value << count) | (value >> ((-count) & mask))); | |
24 | } | |
25 | ||
f1294eaf GS |
26 | static inline unsigned char get_bitmask(uint32_t pos) |
27 | { | |
28 | return ((unsigned char)1) << (pos & (BITS_PER_WORD - 1)); | |
29 | } | |
30 | ||
1217c03e GS |
31 | static int load_bloom_filter_from_graph(struct commit_graph *g, |
32 | struct bloom_filter *filter, | |
33 | struct commit *c) | |
34 | { | |
35 | uint32_t lex_pos, start_index, end_index; | |
36 | ||
37 | while (c->graph_pos < g->num_commits_in_base) | |
38 | g = g->base_graph; | |
39 | ||
40 | /* The commit graph commit 'c' lives in doesn't carry bloom filters. */ | |
41 | if (!g->chunk_bloom_indexes) | |
42 | return 0; | |
43 | ||
44 | lex_pos = c->graph_pos - g->num_commits_in_base; | |
45 | ||
46 | end_index = get_be32(g->chunk_bloom_indexes + 4 * lex_pos); | |
47 | ||
48 | if (lex_pos > 0) | |
49 | start_index = get_be32(g->chunk_bloom_indexes + 4 * (lex_pos - 1)); | |
50 | else | |
51 | start_index = 0; | |
52 | ||
53 | filter->len = end_index - start_index; | |
54 | filter->data = (unsigned char *)(g->chunk_bloom_data + | |
55 | sizeof(unsigned char) * start_index + | |
56 | BLOOMDATA_CHUNK_HEADER_SIZE); | |
57 | ||
58 | return 1; | |
59 | } | |
60 | ||
f52207a4 GS |
61 | /* |
62 | * Calculate the murmur3 32-bit hash value for the given data | |
63 | * using the given seed. | |
64 | * Produces a uniformly distributed hash value. | |
65 | * Not considered to be cryptographically secure. | |
66 | * Implemented as described in https://en.wikipedia.org/wiki/MurmurHash#Algorithm | |
67 | */ | |
68 | uint32_t murmur3_seeded(uint32_t seed, const char *data, size_t len) | |
69 | { | |
70 | const uint32_t c1 = 0xcc9e2d51; | |
71 | const uint32_t c2 = 0x1b873593; | |
72 | const uint32_t r1 = 15; | |
73 | const uint32_t r2 = 13; | |
74 | const uint32_t m = 5; | |
75 | const uint32_t n = 0xe6546b64; | |
76 | int i; | |
77 | uint32_t k1 = 0; | |
78 | const char *tail; | |
79 | ||
80 | int len4 = len / sizeof(uint32_t); | |
81 | ||
82 | uint32_t k; | |
83 | for (i = 0; i < len4; i++) { | |
84 | uint32_t byte1 = (uint32_t)data[4*i]; | |
85 | uint32_t byte2 = ((uint32_t)data[4*i + 1]) << 8; | |
86 | uint32_t byte3 = ((uint32_t)data[4*i + 2]) << 16; | |
87 | uint32_t byte4 = ((uint32_t)data[4*i + 3]) << 24; | |
88 | k = byte1 | byte2 | byte3 | byte4; | |
89 | k *= c1; | |
90 | k = rotate_left(k, r1); | |
91 | k *= c2; | |
92 | ||
93 | seed ^= k; | |
94 | seed = rotate_left(seed, r2) * m + n; | |
95 | } | |
96 | ||
97 | tail = (data + len4 * sizeof(uint32_t)); | |
98 | ||
99 | switch (len & (sizeof(uint32_t) - 1)) { | |
100 | case 3: | |
101 | k1 ^= ((uint32_t)tail[2]) << 16; | |
102 | /*-fallthrough*/ | |
103 | case 2: | |
104 | k1 ^= ((uint32_t)tail[1]) << 8; | |
105 | /*-fallthrough*/ | |
106 | case 1: | |
107 | k1 ^= ((uint32_t)tail[0]) << 0; | |
108 | k1 *= c1; | |
109 | k1 = rotate_left(k1, r1); | |
110 | k1 *= c2; | |
111 | seed ^= k1; | |
112 | break; | |
113 | } | |
114 | ||
115 | seed ^= (uint32_t)len; | |
116 | seed ^= (seed >> 16); | |
117 | seed *= 0x85ebca6b; | |
118 | seed ^= (seed >> 13); | |
119 | seed *= 0xc2b2ae35; | |
120 | seed ^= (seed >> 16); | |
121 | ||
122 | return seed; | |
f1294eaf GS |
123 | } |
124 | ||
125 | void fill_bloom_key(const char *data, | |
126 | size_t len, | |
127 | struct bloom_key *key, | |
128 | const struct bloom_filter_settings *settings) | |
129 | { | |
130 | int i; | |
131 | const uint32_t seed0 = 0x293ae76f; | |
132 | const uint32_t seed1 = 0x7e646e2c; | |
133 | const uint32_t hash0 = murmur3_seeded(seed0, data, len); | |
134 | const uint32_t hash1 = murmur3_seeded(seed1, data, len); | |
135 | ||
136 | key->hashes = (uint32_t *)xcalloc(settings->num_hashes, sizeof(uint32_t)); | |
137 | for (i = 0; i < settings->num_hashes; i++) | |
138 | key->hashes[i] = hash0 + i * hash1; | |
139 | } | |
140 | ||
141 | void add_key_to_filter(const struct bloom_key *key, | |
142 | struct bloom_filter *filter, | |
143 | const struct bloom_filter_settings *settings) | |
144 | { | |
145 | int i; | |
146 | uint64_t mod = filter->len * BITS_PER_WORD; | |
147 | ||
148 | for (i = 0; i < settings->num_hashes; i++) { | |
149 | uint64_t hash_mod = key->hashes[i] % mod; | |
150 | uint64_t block_pos = hash_mod / BITS_PER_WORD; | |
151 | ||
152 | filter->data[block_pos] |= get_bitmask(hash_mod); | |
153 | } | |
154 | } | |
ed591feb GS |
155 | |
156 | void init_bloom_filters(void) | |
157 | { | |
158 | init_bloom_filter_slab(&bloom_filters); | |
159 | } | |
160 | ||
161 | struct bloom_filter *get_bloom_filter(struct repository *r, | |
1217c03e GS |
162 | struct commit *c, |
163 | int compute_if_not_present) | |
ed591feb GS |
164 | { |
165 | struct bloom_filter *filter; | |
166 | struct bloom_filter_settings settings = DEFAULT_BLOOM_FILTER_SETTINGS; | |
167 | int i; | |
168 | struct diff_options diffopt; | |
e3696980 | 169 | int max_changes = 512; |
ed591feb GS |
170 | |
171 | if (bloom_filters.slab_size == 0) | |
172 | return NULL; | |
173 | ||
174 | filter = bloom_filter_slab_at(&bloom_filters, c); | |
175 | ||
1217c03e GS |
176 | if (!filter->data) { |
177 | load_commit_graph_info(r, c); | |
178 | if (c->graph_pos != COMMIT_NOT_FROM_GRAPH && | |
179 | r->objects->commit_graph->chunk_bloom_indexes) { | |
180 | if (load_bloom_filter_from_graph(r->objects->commit_graph, filter, c)) | |
181 | return filter; | |
182 | else | |
183 | return NULL; | |
184 | } | |
185 | } | |
186 | ||
187 | if (filter->data || !compute_if_not_present) | |
188 | return filter; | |
189 | ||
ed591feb GS |
190 | repo_diff_setup(r, &diffopt); |
191 | diffopt.flags.recursive = 1; | |
caf388ca | 192 | diffopt.detect_rename = 0; |
e3696980 | 193 | diffopt.max_changes = max_changes; |
ed591feb GS |
194 | diff_setup_done(&diffopt); |
195 | ||
196 | if (c->parents) | |
197 | diff_tree_oid(&c->parents->item->object.oid, &c->object.oid, "", &diffopt); | |
198 | else | |
199 | diff_tree_oid(NULL, &c->object.oid, "", &diffopt); | |
200 | diffcore_std(&diffopt); | |
201 | ||
e3696980 | 202 | if (diff_queued_diff.nr <= max_changes) { |
ed591feb GS |
203 | struct hashmap pathmap; |
204 | struct pathmap_hash_entry *e; | |
205 | struct hashmap_iter iter; | |
206 | hashmap_init(&pathmap, NULL, NULL, 0); | |
207 | ||
208 | for (i = 0; i < diff_queued_diff.nr; i++) { | |
209 | const char *path = diff_queued_diff.queue[i]->two->path; | |
210 | ||
211 | /* | |
212 | * Add each leading directory of the changed file, i.e. for | |
213 | * 'dir/subdir/file' add 'dir' and 'dir/subdir' as well, so | |
214 | * the Bloom filter could be used to speed up commands like | |
215 | * 'git log dir/subdir', too. | |
216 | * | |
217 | * Note that directories are added without the trailing '/'. | |
218 | */ | |
219 | do { | |
220 | char *last_slash = strrchr(path, '/'); | |
221 | ||
222 | FLEX_ALLOC_STR(e, path, path); | |
223 | hashmap_entry_init(&e->entry, strhash(path)); | |
224 | hashmap_add(&pathmap, &e->entry); | |
225 | ||
226 | if (!last_slash) | |
227 | last_slash = (char*)path; | |
228 | *last_slash = '\0'; | |
229 | ||
230 | } while (*path); | |
231 | ||
232 | diff_free_filepair(diff_queued_diff.queue[i]); | |
233 | } | |
234 | ||
235 | filter->len = (hashmap_get_size(&pathmap) * settings.bits_per_entry + BITS_PER_WORD - 1) / BITS_PER_WORD; | |
236 | filter->data = xcalloc(filter->len, sizeof(unsigned char)); | |
237 | ||
238 | hashmap_for_each_entry(&pathmap, &iter, e, entry) { | |
239 | struct bloom_key key; | |
240 | fill_bloom_key(e->path, strlen(e->path), &key, &settings); | |
241 | add_key_to_filter(&key, filter, &settings); | |
242 | } | |
243 | ||
244 | hashmap_free_entries(&pathmap, struct pathmap_hash_entry, entry); | |
245 | } else { | |
246 | for (i = 0; i < diff_queued_diff.nr; i++) | |
247 | diff_free_filepair(diff_queued_diff.queue[i]); | |
248 | filter->data = NULL; | |
249 | filter->len = 0; | |
250 | } | |
251 | ||
252 | free(diff_queued_diff.queue); | |
253 | DIFF_QUEUE_CLEAR(&diff_queued_diff); | |
254 | ||
255 | return filter; | |
256 | } | |
a56b9464 GS |
257 | |
258 | int bloom_filter_contains(const struct bloom_filter *filter, | |
259 | const struct bloom_key *key, | |
260 | const struct bloom_filter_settings *settings) | |
261 | { | |
262 | int i; | |
263 | uint64_t mod = filter->len * BITS_PER_WORD; | |
264 | ||
265 | if (!mod) | |
266 | return -1; | |
267 | ||
268 | for (i = 0; i < settings->num_hashes; i++) { | |
269 | uint64_t hash_mod = key->hashes[i] % mod; | |
270 | uint64_t block_pos = hash_mod / BITS_PER_WORD; | |
271 | if (!(filter->data[block_pos] & get_bitmask(hash_mod))) | |
272 | return 0; | |
273 | } | |
274 | ||
275 | return 1; | |
276 | } |