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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 | |
6f6f0010 | 36 | pthread_mutex_t _hashes_mtx = PTHREAD_MUTEX_INITIALIZER; |
4db0cff1 QY |
37 | static struct list *_hashes; |
38 | ||
718e3744 | 39 | /* Allocate a new hash. */ |
d62a17ae | 40 | struct hash *hash_create_size(unsigned int size, |
41 | unsigned int (*hash_key)(void *), | |
42 | int (*hash_cmp)(const void *, const void *), | |
43 | const char *name) | |
718e3744 | 44 | { |
d62a17ae | 45 | struct hash *hash; |
46 | ||
47 | assert((size & (size - 1)) == 0); | |
48 | hash = XCALLOC(MTYPE_HASH, sizeof(struct hash)); | |
49 | hash->index = | |
50 | XCALLOC(MTYPE_HASH_INDEX, sizeof(struct hash_backet *) * size); | |
51 | hash->size = size; | |
d62a17ae | 52 | hash->hash_key = hash_key; |
53 | hash->hash_cmp = hash_cmp; | |
54 | hash->count = 0; | |
55 | hash->name = name ? XSTRDUP(MTYPE_HASH, name) : NULL; | |
56 | hash->stats.empty = hash->size; | |
57 | ||
58 | pthread_mutex_lock(&_hashes_mtx); | |
59 | { | |
60 | if (!_hashes) | |
61 | _hashes = list_new(); | |
62 | ||
63 | listnode_add(_hashes, hash); | |
64 | } | |
65 | pthread_mutex_unlock(&_hashes_mtx); | |
66 | ||
67 | return hash; | |
718e3744 | 68 | } |
69 | ||
70 | /* Allocate a new hash with default hash size. */ | |
d62a17ae | 71 | struct hash *hash_create(unsigned int (*hash_key)(void *), |
72 | int (*hash_cmp)(const void *, const void *), | |
73 | const char *name) | |
718e3744 | 74 | { |
d62a17ae | 75 | return hash_create_size(HASH_INITIAL_SIZE, hash_key, hash_cmp, name); |
718e3744 | 76 | } |
77 | ||
78 | /* Utility function for hash_get(). When this function is specified | |
79 | as alloc_func, return arugment as it is. This function is used for | |
80 | intern already allocated value. */ | |
d62a17ae | 81 | void *hash_alloc_intern(void *arg) |
718e3744 | 82 | { |
d62a17ae | 83 | return arg; |
718e3744 | 84 | } |
85 | ||
d62a17ae | 86 | #define hash_update_ssq(hz, old, new) \ |
87 | atomic_fetch_add_explicit(&hz->stats.ssq, (new + old) * (new - old), \ | |
88 | memory_order_relaxed); | |
6f6f0010 | 89 | |
97c84db0 | 90 | /* Expand hash if the chain length exceeds the threshold. */ |
d62a17ae | 91 | static void hash_expand(struct hash *hash) |
97c84db0 | 92 | { |
8b2a6222 | 93 | unsigned int i, new_size; |
d62a17ae | 94 | struct hash_backet *hb, *hbnext, **new_index; |
97c84db0 | 95 | |
d62a17ae | 96 | new_size = hash->size * 2; |
40520c36 DW |
97 | |
98 | if (hash->max_size && new_size > hash->max_size) | |
99 | return; | |
100 | ||
d62a17ae | 101 | new_index = XCALLOC(MTYPE_HASH_INDEX, |
102 | sizeof(struct hash_backet *) * new_size); | |
103 | if (new_index == NULL) | |
104 | return; | |
97c84db0 | 105 | |
d62a17ae | 106 | hash->stats.empty = new_size; |
6f6f0010 | 107 | |
d62a17ae | 108 | for (i = 0; i < hash->size; i++) |
109 | for (hb = hash->index[i]; hb; hb = hbnext) { | |
110 | unsigned int h = hb->key & (new_size - 1); | |
97c84db0 | 111 | |
d62a17ae | 112 | hbnext = hb->next; |
113 | hb->next = new_index[h]; | |
6f6f0010 | 114 | |
d62a17ae | 115 | int oldlen = hb->next ? hb->next->len : 0; |
116 | int newlen = oldlen + 1; | |
6f6f0010 | 117 | |
d62a17ae | 118 | if (newlen == 1) |
119 | hash->stats.empty--; | |
120 | else | |
121 | hb->next->len = 0; | |
6f6f0010 | 122 | |
d62a17ae | 123 | hb->len = newlen; |
6f6f0010 | 124 | |
d62a17ae | 125 | hash_update_ssq(hash, oldlen, newlen); |
6f6f0010 | 126 | |
d62a17ae | 127 | new_index[h] = hb; |
128 | } | |
97c84db0 | 129 | |
d62a17ae | 130 | /* Switch to new table */ |
131 | XFREE(MTYPE_HASH_INDEX, hash->index); | |
132 | hash->size = new_size; | |
133 | hash->index = new_index; | |
97c84db0 SH |
134 | } |
135 | ||
718e3744 | 136 | /* Lookup and return hash backet in hash. If there is no |
137 | corresponding hash backet and alloc_func is specified, create new | |
138 | hash backet. */ | |
d62a17ae | 139 | void *hash_get(struct hash *hash, void *data, void *(*alloc_func)(void *)) |
718e3744 | 140 | { |
d62a17ae | 141 | unsigned int key; |
142 | unsigned int index; | |
143 | void *newdata; | |
d62a17ae | 144 | struct hash_backet *backet; |
145 | ||
146 | key = (*hash->hash_key)(data); | |
147 | index = key & (hash->size - 1); | |
d62a17ae | 148 | |
149 | for (backet = hash->index[index]; backet != NULL; | |
150 | backet = backet->next) { | |
151 | if (backet->key == key && (*hash->hash_cmp)(backet->data, data)) | |
152 | return backet->data; | |
97c84db0 SH |
153 | } |
154 | ||
d62a17ae | 155 | if (alloc_func) { |
156 | newdata = (*alloc_func)(data); | |
157 | if (newdata == NULL) | |
158 | return NULL; | |
6f6f0010 | 159 | |
bed7ad83 | 160 | if (HASH_THRESHOLD(hash->count + 1, hash->size)) { |
d62a17ae | 161 | hash_expand(hash); |
162 | index = key & (hash->size - 1); | |
163 | } | |
6f6f0010 | 164 | |
d62a17ae | 165 | backet = XCALLOC(MTYPE_HASH_BACKET, sizeof(struct hash_backet)); |
166 | backet->data = newdata; | |
167 | backet->key = key; | |
168 | backet->next = hash->index[index]; | |
169 | hash->index[index] = backet; | |
170 | hash->count++; | |
6f6f0010 | 171 | |
d62a17ae | 172 | int oldlen = backet->next ? backet->next->len : 0; |
173 | int newlen = oldlen + 1; | |
6f6f0010 | 174 | |
d62a17ae | 175 | if (newlen == 1) |
176 | hash->stats.empty--; | |
177 | else | |
178 | backet->next->len = 0; | |
6f6f0010 | 179 | |
d62a17ae | 180 | backet->len = newlen; |
181 | ||
182 | hash_update_ssq(hash, oldlen, newlen); | |
183 | ||
184 | return backet->data; | |
185 | } | |
186 | return NULL; | |
718e3744 | 187 | } |
188 | ||
189 | /* Hash lookup. */ | |
d62a17ae | 190 | void *hash_lookup(struct hash *hash, void *data) |
718e3744 | 191 | { |
d62a17ae | 192 | return hash_get(hash, data, NULL); |
718e3744 | 193 | } |
194 | ||
6392aa83 | 195 | /* Simple Bernstein hash which is simple and fast for common case */ |
d62a17ae | 196 | unsigned int string_hash_make(const char *str) |
6392aa83 | 197 | { |
d62a17ae | 198 | unsigned int hash = 0; |
6392aa83 | 199 | |
d62a17ae | 200 | while (*str) |
201 | hash = (hash * 33) ^ (unsigned int)*str++; | |
6392aa83 | 202 | |
d62a17ae | 203 | return hash; |
6392aa83 SH |
204 | } |
205 | ||
718e3744 | 206 | /* This function release registered value from specified hash. When |
207 | release is successfully finished, return the data pointer in the | |
208 | hash backet. */ | |
d62a17ae | 209 | void *hash_release(struct hash *hash, void *data) |
718e3744 | 210 | { |
d62a17ae | 211 | void *ret; |
212 | unsigned int key; | |
213 | unsigned int index; | |
214 | struct hash_backet *backet; | |
215 | struct hash_backet *pp; | |
216 | ||
217 | key = (*hash->hash_key)(data); | |
218 | index = key & (hash->size - 1); | |
219 | ||
220 | for (backet = pp = hash->index[index]; backet; backet = backet->next) { | |
221 | if (backet->key == key | |
222 | && (*hash->hash_cmp)(backet->data, data)) { | |
223 | int oldlen = hash->index[index]->len; | |
224 | int newlen = oldlen - 1; | |
225 | ||
226 | if (backet == pp) | |
227 | hash->index[index] = backet->next; | |
228 | else | |
229 | pp->next = backet->next; | |
230 | ||
231 | if (hash->index[index]) | |
232 | hash->index[index]->len = newlen; | |
233 | else | |
234 | hash->stats.empty++; | |
235 | ||
236 | hash_update_ssq(hash, oldlen, newlen); | |
237 | ||
238 | ret = backet->data; | |
239 | XFREE(MTYPE_HASH_BACKET, backet); | |
240 | hash->count--; | |
241 | return ret; | |
242 | } | |
243 | pp = backet; | |
718e3744 | 244 | } |
d62a17ae | 245 | return NULL; |
718e3744 | 246 | } |
247 | ||
248 | /* Iterator function for hash. */ | |
d62a17ae | 249 | void hash_iterate(struct hash *hash, void (*func)(struct hash_backet *, void *), |
250 | void *arg) | |
718e3744 | 251 | { |
d62a17ae | 252 | unsigned int i; |
253 | struct hash_backet *hb; | |
254 | struct hash_backet *hbnext; | |
255 | ||
256 | for (i = 0; i < hash->size; i++) | |
257 | for (hb = hash->index[i]; hb; hb = hbnext) { | |
258 | /* get pointer to next hash backet here, in case (*func) | |
259 | * decides to delete hb by calling hash_release | |
260 | */ | |
261 | hbnext = hb->next; | |
262 | (*func)(hb, arg); | |
263 | } | |
718e3744 | 264 | } |
265 | ||
3f9c7369 | 266 | /* Iterator function for hash. */ |
d62a17ae | 267 | void hash_walk(struct hash *hash, int (*func)(struct hash_backet *, void *), |
268 | void *arg) | |
3f9c7369 | 269 | { |
d62a17ae | 270 | unsigned int i; |
271 | struct hash_backet *hb; | |
272 | struct hash_backet *hbnext; | |
273 | int ret = HASHWALK_CONTINUE; | |
274 | ||
275 | for (i = 0; i < hash->size; i++) { | |
276 | for (hb = hash->index[i]; hb; hb = hbnext) { | |
277 | /* get pointer to next hash backet here, in case (*func) | |
278 | * decides to delete hb by calling hash_release | |
279 | */ | |
280 | hbnext = hb->next; | |
281 | ret = (*func)(hb, arg); | |
282 | if (ret == HASHWALK_ABORT) | |
283 | return; | |
284 | } | |
3f9c7369 | 285 | } |
3f9c7369 DS |
286 | } |
287 | ||
718e3744 | 288 | /* Clean up hash. */ |
d62a17ae | 289 | void hash_clean(struct hash *hash, void (*free_func)(void *)) |
718e3744 | 290 | { |
d62a17ae | 291 | unsigned int i; |
292 | struct hash_backet *hb; | |
293 | struct hash_backet *next; | |
718e3744 | 294 | |
d62a17ae | 295 | for (i = 0; i < hash->size; i++) { |
296 | for (hb = hash->index[i]; hb; hb = next) { | |
297 | next = hb->next; | |
298 | ||
299 | if (free_func) | |
300 | (*free_func)(hb->data); | |
718e3744 | 301 | |
d62a17ae | 302 | XFREE(MTYPE_HASH_BACKET, hb); |
303 | hash->count--; | |
304 | } | |
305 | hash->index[i] = NULL; | |
718e3744 | 306 | } |
6f6f0010 | 307 | |
d62a17ae | 308 | hash->stats.ssq = 0; |
309 | hash->stats.empty = hash->size; | |
718e3744 | 310 | } |
311 | ||
312 | /* Free hash memory. You may call hash_clean before call this | |
313 | function. */ | |
d62a17ae | 314 | void hash_free(struct hash *hash) |
718e3744 | 315 | { |
d62a17ae | 316 | pthread_mutex_lock(&_hashes_mtx); |
317 | { | |
318 | if (_hashes) { | |
319 | listnode_delete(_hashes, hash); | |
320 | if (_hashes->count == 0) { | |
321 | list_delete(_hashes); | |
322 | _hashes = NULL; | |
323 | } | |
324 | } | |
325 | } | |
326 | pthread_mutex_unlock(&_hashes_mtx); | |
327 | ||
328 | if (hash->name) | |
329 | XFREE(MTYPE_HASH, hash->name); | |
330 | ||
331 | XFREE(MTYPE_HASH_INDEX, hash->index); | |
332 | XFREE(MTYPE_HASH, hash); | |
4db0cff1 QY |
333 | } |
334 | ||
6f6f0010 QY |
335 | |
336 | /* CLI commands ------------------------------------------------------------ */ | |
4db0cff1 | 337 | |
40818cec DL |
338 | DEFUN_NOSH(show_hash_stats, |
339 | show_hash_stats_cmd, | |
340 | "show debugging hashtable [statistics]", | |
341 | SHOW_STR | |
342 | DEBUG_STR | |
343 | "Statistics about hash tables\n" | |
344 | "Statistics about hash tables\n") | |
4db0cff1 | 345 | { |
d62a17ae | 346 | struct hash *h; |
347 | struct listnode *ln; | |
348 | struct ttable *tt = ttable_new(&ttable_styles[TTSTYLE_BLANK]); | |
349 | ||
350 | ttable_add_row(tt, "Hash table|Buckets|Entries|Empty|LF|SD|FLF|SD"); | |
351 | tt->style.cell.lpad = 2; | |
352 | tt->style.cell.rpad = 1; | |
353 | tt->style.corner = '+'; | |
354 | ttable_restyle(tt); | |
355 | ttable_rowseps(tt, 0, BOTTOM, true, '-'); | |
356 | ||
357 | /* Summary statistics calculated are: | |
358 | * | |
c7d3895e CF |
359 | * - Load factor: This is the number of elements in the table divided |
360 | * by the number of buckets. Since this hash table implementation | |
361 | * uses chaining, this value can be greater than 1. | |
362 | * This number provides information on how 'full' the table is, but | |
363 | * does not provide information on how evenly distributed the | |
364 | * elements are. | |
365 | * Notably, a load factor >= 1 does not imply that every bucket has | |
366 | * an element; with a pathological hash function, all elements could | |
367 | * be in a single bucket. | |
d62a17ae | 368 | * |
369 | * - Full load factor: this is the number of elements in the table | |
c7d3895e | 370 | * divided by the number of buckets that have some elements in them. |
d62a17ae | 371 | * |
372 | * - Std. Dev.: This is the standard deviation calculated from the | |
c7d3895e CF |
373 | * relevant load factor. If the load factor is the mean of number of |
374 | * elements per bucket, the standard deviation measures how much any | |
375 | * particular bucket is likely to deviate from the mean. | |
376 | * As a rule of thumb this number should be less than 2, and ideally | |
377 | * <= 1 for optimal performance. A number larger than 3 generally | |
378 | * indicates a poor hash function. | |
d62a17ae | 379 | */ |
380 | ||
381 | double lf; // load factor | |
382 | double flf; // full load factor | |
383 | double var; // overall variance | |
384 | double fvar; // full variance | |
385 | double stdv; // overall stddev | |
386 | double fstdv; // full stddev | |
387 | ||
388 | long double x2; // h->count ^ 2 | |
389 | long double ldc; // (long double) h->count | |
390 | long double full; // h->size - h->stats.empty | |
391 | long double ssq; // ssq casted to long double | |
392 | ||
393 | pthread_mutex_lock(&_hashes_mtx); | |
394 | if (!_hashes) { | |
395 | pthread_mutex_unlock(&_hashes_mtx); | |
396 | vty_out(vty, "No hash tables in use.\n"); | |
397 | return CMD_SUCCESS; | |
398 | } | |
399 | ||
400 | for (ALL_LIST_ELEMENTS_RO(_hashes, ln, h)) { | |
401 | if (!h->name) | |
402 | continue; | |
403 | ||
404 | ssq = (long double)h->stats.ssq; | |
61b9e9d6 | 405 | x2 = h->count * h->count; |
d62a17ae | 406 | ldc = (long double)h->count; |
407 | full = h->size - h->stats.empty; | |
408 | lf = h->count / (double)h->size; | |
409 | flf = full ? h->count / (double)(full) : 0; | |
410 | var = ldc ? (1.0 / ldc) * (ssq - x2 / ldc) : 0; | |
411 | fvar = full ? (1.0 / full) * (ssq - x2 / full) : 0; | |
412 | var = (var < .0001) ? 0 : var; | |
413 | fvar = (fvar < .0001) ? 0 : fvar; | |
414 | stdv = sqrt(var); | |
415 | fstdv = sqrt(fvar); | |
416 | ||
417 | ttable_add_row(tt, "%s|%d|%ld|%.0f%%|%.2lf|%.2lf|%.2lf|%.2lf", | |
418 | h->name, h->size, h->count, | |
419 | (h->stats.empty / (double)h->size) * 100, lf, | |
420 | stdv, flf, fstdv); | |
421 | } | |
422 | pthread_mutex_unlock(&_hashes_mtx); | |
423 | ||
424 | /* display header */ | |
425 | char header[] = "Showing hash table statistics for "; | |
426 | char underln[sizeof(header) + strlen(frr_protonameinst)]; | |
427 | memset(underln, '-', sizeof(underln)); | |
428 | underln[sizeof(underln) - 1] = '\0'; | |
429 | vty_out(vty, "%s%s\n", header, frr_protonameinst); | |
430 | vty_out(vty, "%s\n", underln); | |
431 | ||
432 | vty_out(vty, "# allocated: %d\n", _hashes->count); | |
433 | vty_out(vty, "# named: %d\n\n", tt->nrows - 1); | |
434 | ||
435 | if (tt->nrows > 1) { | |
436 | ttable_colseps(tt, 0, RIGHT, true, '|'); | |
437 | char *table = ttable_dump(tt, "\n"); | |
438 | vty_out(vty, "%s\n", table); | |
439 | XFREE(MTYPE_TMP, table); | |
440 | } else | |
441 | vty_out(vty, "No named hash tables to display.\n"); | |
442 | ||
443 | ttable_del(tt); | |
444 | ||
445 | return CMD_SUCCESS; | |
4db0cff1 QY |
446 | } |
447 | ||
d62a17ae | 448 | void hash_cmd_init() |
4db0cff1 | 449 | { |
d62a17ae | 450 | install_element(ENABLE_NODE, &show_hash_stats_cmd); |
4db0cff1 | 451 | } |