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718e3744 | 1 | /* Hash routine. |
2 | * Copyright (C) 1998 Kunihiro Ishiguro | |
3 | * | |
4 | * This file is part of GNU Zebra. | |
5 | * | |
6 | * GNU Zebra is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published | |
8 | * by the Free Software Foundation; either version 2, or (at your | |
9 | * option) any later version. | |
10 | * | |
11 | * GNU Zebra is distributed in the hope that it will be useful, but | |
12 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | * General Public License for more details. | |
15 | * | |
896014f4 DL |
16 | * You should have received a copy of the GNU General Public License along |
17 | * with this program; see the file COPYING; if not, write to the Free Software | |
18 | * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
718e3744 | 19 | */ |
20 | ||
21 | #include <zebra.h> | |
4db0cff1 | 22 | #include <math.h> |
718e3744 | 23 | |
24 | #include "hash.h" | |
25 | #include "memory.h" | |
4db0cff1 QY |
26 | #include "linklist.h" |
27 | #include "termtable.h" | |
28 | #include "vty.h" | |
29 | #include "command.h" | |
6f6f0010 | 30 | #include "libfrr.h" |
718e3744 | 31 | |
d62a17ae | 32 | DEFINE_MTYPE(LIB, HASH, "Hash") |
33 | DEFINE_MTYPE(LIB, HASH_BACKET, "Hash Bucket") | |
34 | DEFINE_MTYPE_STATIC(LIB, HASH_INDEX, "Hash Index") | |
4a1ab8e4 | 35 | |
c17faa4b | 36 | static pthread_mutex_t _hashes_mtx = PTHREAD_MUTEX_INITIALIZER; |
4db0cff1 QY |
37 | static struct list *_hashes; |
38 | ||
d62a17ae | 39 | struct hash *hash_create_size(unsigned int size, |
40 | unsigned int (*hash_key)(void *), | |
74df8d6d | 41 | bool (*hash_cmp)(const void *, const void *), |
d62a17ae | 42 | const char *name) |
718e3744 | 43 | { |
d62a17ae | 44 | struct hash *hash; |
45 | ||
46 | assert((size & (size - 1)) == 0); | |
47 | hash = XCALLOC(MTYPE_HASH, sizeof(struct hash)); | |
48 | hash->index = | |
e3b78da8 | 49 | XCALLOC(MTYPE_HASH_INDEX, sizeof(struct hash_bucket *) * size); |
d62a17ae | 50 | hash->size = size; |
d62a17ae | 51 | hash->hash_key = hash_key; |
52 | hash->hash_cmp = hash_cmp; | |
53 | hash->count = 0; | |
54 | hash->name = name ? XSTRDUP(MTYPE_HASH, name) : NULL; | |
55 | hash->stats.empty = hash->size; | |
56 | ||
57 | pthread_mutex_lock(&_hashes_mtx); | |
58 | { | |
59 | if (!_hashes) | |
60 | _hashes = list_new(); | |
61 | ||
62 | listnode_add(_hashes, hash); | |
63 | } | |
64 | pthread_mutex_unlock(&_hashes_mtx); | |
65 | ||
66 | return hash; | |
718e3744 | 67 | } |
68 | ||
d62a17ae | 69 | struct hash *hash_create(unsigned int (*hash_key)(void *), |
74df8d6d | 70 | bool (*hash_cmp)(const void *, const void *), |
d62a17ae | 71 | const char *name) |
718e3744 | 72 | { |
d62a17ae | 73 | return hash_create_size(HASH_INITIAL_SIZE, hash_key, hash_cmp, name); |
718e3744 | 74 | } |
75 | ||
d62a17ae | 76 | void *hash_alloc_intern(void *arg) |
718e3744 | 77 | { |
d62a17ae | 78 | return arg; |
718e3744 | 79 | } |
80 | ||
d62a17ae | 81 | #define hash_update_ssq(hz, old, new) \ |
82 | atomic_fetch_add_explicit(&hz->stats.ssq, (new + old) * (new - old), \ | |
83 | memory_order_relaxed); | |
6f6f0010 | 84 | |
97c84db0 | 85 | /* Expand hash if the chain length exceeds the threshold. */ |
d62a17ae | 86 | static void hash_expand(struct hash *hash) |
97c84db0 | 87 | { |
8b2a6222 | 88 | unsigned int i, new_size; |
e3b78da8 | 89 | struct hash_bucket *hb, *hbnext, **new_index; |
97c84db0 | 90 | |
d62a17ae | 91 | new_size = hash->size * 2; |
40520c36 DW |
92 | |
93 | if (hash->max_size && new_size > hash->max_size) | |
94 | return; | |
95 | ||
d62a17ae | 96 | new_index = XCALLOC(MTYPE_HASH_INDEX, |
e3b78da8 | 97 | sizeof(struct hash_bucket *) * new_size); |
97c84db0 | 98 | |
d62a17ae | 99 | hash->stats.empty = new_size; |
6f6f0010 | 100 | |
d62a17ae | 101 | for (i = 0; i < hash->size; i++) |
102 | for (hb = hash->index[i]; hb; hb = hbnext) { | |
103 | unsigned int h = hb->key & (new_size - 1); | |
97c84db0 | 104 | |
d62a17ae | 105 | hbnext = hb->next; |
106 | hb->next = new_index[h]; | |
6f6f0010 | 107 | |
d62a17ae | 108 | int oldlen = hb->next ? hb->next->len : 0; |
109 | int newlen = oldlen + 1; | |
6f6f0010 | 110 | |
d62a17ae | 111 | if (newlen == 1) |
112 | hash->stats.empty--; | |
113 | else | |
114 | hb->next->len = 0; | |
6f6f0010 | 115 | |
d62a17ae | 116 | hb->len = newlen; |
6f6f0010 | 117 | |
d62a17ae | 118 | hash_update_ssq(hash, oldlen, newlen); |
6f6f0010 | 119 | |
d62a17ae | 120 | new_index[h] = hb; |
121 | } | |
97c84db0 | 122 | |
d62a17ae | 123 | /* Switch to new table */ |
124 | XFREE(MTYPE_HASH_INDEX, hash->index); | |
125 | hash->size = new_size; | |
126 | hash->index = new_index; | |
97c84db0 SH |
127 | } |
128 | ||
d62a17ae | 129 | void *hash_get(struct hash *hash, void *data, void *(*alloc_func)(void *)) |
718e3744 | 130 | { |
d62a17ae | 131 | unsigned int key; |
132 | unsigned int index; | |
133 | void *newdata; | |
e3b78da8 | 134 | struct hash_bucket *bucket; |
d62a17ae | 135 | |
efb149d9 DS |
136 | if (!alloc_func && !hash->count) |
137 | return NULL; | |
138 | ||
d62a17ae | 139 | key = (*hash->hash_key)(data); |
140 | index = key & (hash->size - 1); | |
d62a17ae | 141 | |
e3b78da8 TB |
142 | for (bucket = hash->index[index]; bucket != NULL; |
143 | bucket = bucket->next) { | |
144 | if (bucket->key == key && (*hash->hash_cmp)(bucket->data, data)) | |
145 | return bucket->data; | |
97c84db0 SH |
146 | } |
147 | ||
d62a17ae | 148 | if (alloc_func) { |
149 | newdata = (*alloc_func)(data); | |
150 | if (newdata == NULL) | |
151 | return NULL; | |
6f6f0010 | 152 | |
bed7ad83 | 153 | if (HASH_THRESHOLD(hash->count + 1, hash->size)) { |
d62a17ae | 154 | hash_expand(hash); |
155 | index = key & (hash->size - 1); | |
156 | } | |
6f6f0010 | 157 | |
e3b78da8 TB |
158 | bucket = XCALLOC(MTYPE_HASH_BACKET, sizeof(struct hash_bucket)); |
159 | bucket->data = newdata; | |
160 | bucket->key = key; | |
161 | bucket->next = hash->index[index]; | |
162 | hash->index[index] = bucket; | |
d62a17ae | 163 | hash->count++; |
6f6f0010 | 164 | |
e3b78da8 | 165 | int oldlen = bucket->next ? bucket->next->len : 0; |
d62a17ae | 166 | int newlen = oldlen + 1; |
6f6f0010 | 167 | |
d62a17ae | 168 | if (newlen == 1) |
169 | hash->stats.empty--; | |
170 | else | |
e3b78da8 | 171 | bucket->next->len = 0; |
6f6f0010 | 172 | |
e3b78da8 | 173 | bucket->len = newlen; |
d62a17ae | 174 | |
175 | hash_update_ssq(hash, oldlen, newlen); | |
176 | ||
e3b78da8 | 177 | return bucket->data; |
d62a17ae | 178 | } |
179 | return NULL; | |
718e3744 | 180 | } |
181 | ||
d62a17ae | 182 | void *hash_lookup(struct hash *hash, void *data) |
718e3744 | 183 | { |
d62a17ae | 184 | return hash_get(hash, data, NULL); |
718e3744 | 185 | } |
186 | ||
d62a17ae | 187 | unsigned int string_hash_make(const char *str) |
6392aa83 | 188 | { |
d62a17ae | 189 | unsigned int hash = 0; |
6392aa83 | 190 | |
d62a17ae | 191 | while (*str) |
192 | hash = (hash * 33) ^ (unsigned int)*str++; | |
6392aa83 | 193 | |
d62a17ae | 194 | return hash; |
6392aa83 SH |
195 | } |
196 | ||
d62a17ae | 197 | void *hash_release(struct hash *hash, void *data) |
718e3744 | 198 | { |
d62a17ae | 199 | void *ret; |
200 | unsigned int key; | |
201 | unsigned int index; | |
e3b78da8 TB |
202 | struct hash_bucket *bucket; |
203 | struct hash_bucket *pp; | |
d62a17ae | 204 | |
205 | key = (*hash->hash_key)(data); | |
206 | index = key & (hash->size - 1); | |
207 | ||
e3b78da8 TB |
208 | for (bucket = pp = hash->index[index]; bucket; bucket = bucket->next) { |
209 | if (bucket->key == key | |
210 | && (*hash->hash_cmp)(bucket->data, data)) { | |
d62a17ae | 211 | int oldlen = hash->index[index]->len; |
212 | int newlen = oldlen - 1; | |
213 | ||
e3b78da8 TB |
214 | if (bucket == pp) |
215 | hash->index[index] = bucket->next; | |
d62a17ae | 216 | else |
e3b78da8 | 217 | pp->next = bucket->next; |
d62a17ae | 218 | |
219 | if (hash->index[index]) | |
220 | hash->index[index]->len = newlen; | |
221 | else | |
222 | hash->stats.empty++; | |
223 | ||
224 | hash_update_ssq(hash, oldlen, newlen); | |
225 | ||
e3b78da8 TB |
226 | ret = bucket->data; |
227 | XFREE(MTYPE_HASH_BACKET, bucket); | |
d62a17ae | 228 | hash->count--; |
229 | return ret; | |
230 | } | |
e3b78da8 | 231 | pp = bucket; |
718e3744 | 232 | } |
d62a17ae | 233 | return NULL; |
718e3744 | 234 | } |
235 | ||
e3b78da8 | 236 | void hash_iterate(struct hash *hash, void (*func)(struct hash_bucket *, void *), |
d62a17ae | 237 | void *arg) |
718e3744 | 238 | { |
d62a17ae | 239 | unsigned int i; |
e3b78da8 TB |
240 | struct hash_bucket *hb; |
241 | struct hash_bucket *hbnext; | |
d62a17ae | 242 | |
df66eb2e | 243 | for (i = 0; i < hash->size; i++) |
d62a17ae | 244 | for (hb = hash->index[i]; hb; hb = hbnext) { |
e3b78da8 | 245 | /* get pointer to next hash bucket here, in case (*func) |
d62a17ae | 246 | * decides to delete hb by calling hash_release |
247 | */ | |
248 | hbnext = hb->next; | |
249 | (*func)(hb, arg); | |
250 | } | |
718e3744 | 251 | } |
252 | ||
e3b78da8 | 253 | void hash_walk(struct hash *hash, int (*func)(struct hash_bucket *, void *), |
d62a17ae | 254 | void *arg) |
3f9c7369 | 255 | { |
d62a17ae | 256 | unsigned int i; |
e3b78da8 TB |
257 | struct hash_bucket *hb; |
258 | struct hash_bucket *hbnext; | |
d62a17ae | 259 | int ret = HASHWALK_CONTINUE; |
260 | ||
261 | for (i = 0; i < hash->size; i++) { | |
262 | for (hb = hash->index[i]; hb; hb = hbnext) { | |
e3b78da8 | 263 | /* get pointer to next hash bucket here, in case (*func) |
d62a17ae | 264 | * decides to delete hb by calling hash_release |
265 | */ | |
266 | hbnext = hb->next; | |
267 | ret = (*func)(hb, arg); | |
268 | if (ret == HASHWALK_ABORT) | |
269 | return; | |
270 | } | |
3f9c7369 | 271 | } |
3f9c7369 DS |
272 | } |
273 | ||
d62a17ae | 274 | void hash_clean(struct hash *hash, void (*free_func)(void *)) |
718e3744 | 275 | { |
d62a17ae | 276 | unsigned int i; |
e3b78da8 TB |
277 | struct hash_bucket *hb; |
278 | struct hash_bucket *next; | |
718e3744 | 279 | |
d62a17ae | 280 | for (i = 0; i < hash->size; i++) { |
281 | for (hb = hash->index[i]; hb; hb = next) { | |
282 | next = hb->next; | |
283 | ||
284 | if (free_func) | |
285 | (*free_func)(hb->data); | |
718e3744 | 286 | |
d62a17ae | 287 | XFREE(MTYPE_HASH_BACKET, hb); |
288 | hash->count--; | |
289 | } | |
290 | hash->index[i] = NULL; | |
718e3744 | 291 | } |
6f6f0010 | 292 | |
d62a17ae | 293 | hash->stats.ssq = 0; |
294 | hash->stats.empty = hash->size; | |
718e3744 | 295 | } |
296 | ||
e3b78da8 | 297 | static void hash_to_list_iter(struct hash_bucket *hb, void *arg) |
91f10370 QY |
298 | { |
299 | struct list *list = arg; | |
300 | ||
301 | listnode_add(list, hb->data); | |
302 | } | |
303 | ||
304 | struct list *hash_to_list(struct hash *hash) | |
305 | { | |
306 | struct list *list = list_new(); | |
307 | ||
308 | hash_iterate(hash, hash_to_list_iter, list); | |
309 | return list; | |
310 | } | |
311 | ||
d62a17ae | 312 | void hash_free(struct hash *hash) |
718e3744 | 313 | { |
d62a17ae | 314 | pthread_mutex_lock(&_hashes_mtx); |
315 | { | |
316 | if (_hashes) { | |
317 | listnode_delete(_hashes, hash); | |
318 | if (_hashes->count == 0) { | |
6a154c88 | 319 | list_delete(&_hashes); |
d62a17ae | 320 | } |
321 | } | |
322 | } | |
323 | pthread_mutex_unlock(&_hashes_mtx); | |
324 | ||
0a22ddfb | 325 | XFREE(MTYPE_HASH, hash->name); |
d62a17ae | 326 | |
327 | XFREE(MTYPE_HASH_INDEX, hash->index); | |
328 | XFREE(MTYPE_HASH, hash); | |
4db0cff1 QY |
329 | } |
330 | ||
6f6f0010 QY |
331 | |
332 | /* CLI commands ------------------------------------------------------------ */ | |
4db0cff1 | 333 | |
40818cec DL |
334 | DEFUN_NOSH(show_hash_stats, |
335 | show_hash_stats_cmd, | |
336 | "show debugging hashtable [statistics]", | |
337 | SHOW_STR | |
338 | DEBUG_STR | |
339 | "Statistics about hash tables\n" | |
340 | "Statistics about hash tables\n") | |
4db0cff1 | 341 | { |
d62a17ae | 342 | struct hash *h; |
343 | struct listnode *ln; | |
344 | struct ttable *tt = ttable_new(&ttable_styles[TTSTYLE_BLANK]); | |
345 | ||
346 | ttable_add_row(tt, "Hash table|Buckets|Entries|Empty|LF|SD|FLF|SD"); | |
347 | tt->style.cell.lpad = 2; | |
348 | tt->style.cell.rpad = 1; | |
349 | tt->style.corner = '+'; | |
350 | ttable_restyle(tt); | |
351 | ttable_rowseps(tt, 0, BOTTOM, true, '-'); | |
352 | ||
353 | /* Summary statistics calculated are: | |
354 | * | |
c7d3895e CF |
355 | * - Load factor: This is the number of elements in the table divided |
356 | * by the number of buckets. Since this hash table implementation | |
357 | * uses chaining, this value can be greater than 1. | |
358 | * This number provides information on how 'full' the table is, but | |
359 | * does not provide information on how evenly distributed the | |
360 | * elements are. | |
361 | * Notably, a load factor >= 1 does not imply that every bucket has | |
362 | * an element; with a pathological hash function, all elements could | |
363 | * be in a single bucket. | |
d62a17ae | 364 | * |
365 | * - Full load factor: this is the number of elements in the table | |
c7d3895e | 366 | * divided by the number of buckets that have some elements in them. |
d62a17ae | 367 | * |
368 | * - Std. Dev.: This is the standard deviation calculated from the | |
c7d3895e CF |
369 | * relevant load factor. If the load factor is the mean of number of |
370 | * elements per bucket, the standard deviation measures how much any | |
371 | * particular bucket is likely to deviate from the mean. | |
372 | * As a rule of thumb this number should be less than 2, and ideally | |
373 | * <= 1 for optimal performance. A number larger than 3 generally | |
374 | * indicates a poor hash function. | |
d62a17ae | 375 | */ |
376 | ||
377 | double lf; // load factor | |
378 | double flf; // full load factor | |
379 | double var; // overall variance | |
380 | double fvar; // full variance | |
381 | double stdv; // overall stddev | |
382 | double fstdv; // full stddev | |
383 | ||
384 | long double x2; // h->count ^ 2 | |
385 | long double ldc; // (long double) h->count | |
386 | long double full; // h->size - h->stats.empty | |
387 | long double ssq; // ssq casted to long double | |
388 | ||
389 | pthread_mutex_lock(&_hashes_mtx); | |
390 | if (!_hashes) { | |
391 | pthread_mutex_unlock(&_hashes_mtx); | |
44f12f20 | 392 | ttable_del(tt); |
d62a17ae | 393 | vty_out(vty, "No hash tables in use.\n"); |
394 | return CMD_SUCCESS; | |
395 | } | |
396 | ||
397 | for (ALL_LIST_ELEMENTS_RO(_hashes, ln, h)) { | |
398 | if (!h->name) | |
399 | continue; | |
400 | ||
401 | ssq = (long double)h->stats.ssq; | |
61b9e9d6 | 402 | x2 = h->count * h->count; |
d62a17ae | 403 | ldc = (long double)h->count; |
404 | full = h->size - h->stats.empty; | |
405 | lf = h->count / (double)h->size; | |
406 | flf = full ? h->count / (double)(full) : 0; | |
407 | var = ldc ? (1.0 / ldc) * (ssq - x2 / ldc) : 0; | |
408 | fvar = full ? (1.0 / full) * (ssq - x2 / full) : 0; | |
409 | var = (var < .0001) ? 0 : var; | |
410 | fvar = (fvar < .0001) ? 0 : fvar; | |
411 | stdv = sqrt(var); | |
412 | fstdv = sqrt(fvar); | |
413 | ||
414 | ttable_add_row(tt, "%s|%d|%ld|%.0f%%|%.2lf|%.2lf|%.2lf|%.2lf", | |
415 | h->name, h->size, h->count, | |
416 | (h->stats.empty / (double)h->size) * 100, lf, | |
417 | stdv, flf, fstdv); | |
418 | } | |
419 | pthread_mutex_unlock(&_hashes_mtx); | |
420 | ||
421 | /* display header */ | |
422 | char header[] = "Showing hash table statistics for "; | |
423 | char underln[sizeof(header) + strlen(frr_protonameinst)]; | |
424 | memset(underln, '-', sizeof(underln)); | |
425 | underln[sizeof(underln) - 1] = '\0'; | |
426 | vty_out(vty, "%s%s\n", header, frr_protonameinst); | |
427 | vty_out(vty, "%s\n", underln); | |
428 | ||
429 | vty_out(vty, "# allocated: %d\n", _hashes->count); | |
430 | vty_out(vty, "# named: %d\n\n", tt->nrows - 1); | |
431 | ||
432 | if (tt->nrows > 1) { | |
433 | ttable_colseps(tt, 0, RIGHT, true, '|'); | |
434 | char *table = ttable_dump(tt, "\n"); | |
435 | vty_out(vty, "%s\n", table); | |
436 | XFREE(MTYPE_TMP, table); | |
437 | } else | |
438 | vty_out(vty, "No named hash tables to display.\n"); | |
439 | ||
440 | ttable_del(tt); | |
441 | ||
442 | return CMD_SUCCESS; | |
4db0cff1 QY |
443 | } |
444 | ||
4d762f26 | 445 | void hash_cmd_init(void) |
4db0cff1 | 446 | { |
d62a17ae | 447 | install_element(ENABLE_NODE, &show_hash_stats_cmd); |
4db0cff1 | 448 | } |