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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" |
00dffa8c | 31 | #include "frr_pthread.h" |
abf96a87 | 32 | #include "trace.h" |
718e3744 | 33 | |
eaf58ba9 DL |
34 | DEFINE_MTYPE_STATIC(LIB, HASH, "Hash") |
35 | DEFINE_MTYPE_STATIC(LIB, HASH_BACKET, "Hash Bucket") | |
d62a17ae | 36 | DEFINE_MTYPE_STATIC(LIB, HASH_INDEX, "Hash Index") |
4a1ab8e4 | 37 | |
c17faa4b | 38 | static pthread_mutex_t _hashes_mtx = PTHREAD_MUTEX_INITIALIZER; |
4db0cff1 QY |
39 | static struct list *_hashes; |
40 | ||
d62a17ae | 41 | struct hash *hash_create_size(unsigned int size, |
d8b87afe | 42 | unsigned int (*hash_key)(const void *), |
74df8d6d | 43 | bool (*hash_cmp)(const void *, const void *), |
d62a17ae | 44 | const char *name) |
718e3744 | 45 | { |
d62a17ae | 46 | struct hash *hash; |
47 | ||
48 | assert((size & (size - 1)) == 0); | |
49 | hash = XCALLOC(MTYPE_HASH, sizeof(struct hash)); | |
50 | hash->index = | |
e3b78da8 | 51 | XCALLOC(MTYPE_HASH_INDEX, sizeof(struct hash_bucket *) * size); |
d62a17ae | 52 | hash->size = size; |
d62a17ae | 53 | hash->hash_key = hash_key; |
54 | hash->hash_cmp = hash_cmp; | |
55 | hash->count = 0; | |
56 | hash->name = name ? XSTRDUP(MTYPE_HASH, name) : NULL; | |
57 | hash->stats.empty = hash->size; | |
58 | ||
00dffa8c | 59 | frr_with_mutex(&_hashes_mtx) { |
d62a17ae | 60 | if (!_hashes) |
61 | _hashes = list_new(); | |
62 | ||
63 | listnode_add(_hashes, hash); | |
64 | } | |
d62a17ae | 65 | |
66 | return hash; | |
718e3744 | 67 | } |
68 | ||
d8b87afe | 69 | struct hash *hash_create(unsigned int (*hash_key)(const 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 | ||
e6464fdc QY |
81 | /* |
82 | * ssq = ssq + (new^2 - old^2) | |
83 | * = ssq + ((new + old) * (new - old)) | |
84 | */ | |
d62a17ae | 85 | #define hash_update_ssq(hz, old, new) \ |
e6464fdc QY |
86 | do { \ |
87 | int _adjust = (new + old) * (new - old); \ | |
88 | if (_adjust < 0) \ | |
89 | atomic_fetch_sub_explicit(&hz->stats.ssq, -_adjust, \ | |
90 | memory_order_relaxed); \ | |
91 | else \ | |
92 | atomic_fetch_add_explicit(&hz->stats.ssq, _adjust, \ | |
93 | memory_order_relaxed); \ | |
94 | } while (0) | |
6f6f0010 | 95 | |
97c84db0 | 96 | /* Expand hash if the chain length exceeds the threshold. */ |
d62a17ae | 97 | static void hash_expand(struct hash *hash) |
97c84db0 | 98 | { |
8b2a6222 | 99 | unsigned int i, new_size; |
e3b78da8 | 100 | struct hash_bucket *hb, *hbnext, **new_index; |
97c84db0 | 101 | |
d62a17ae | 102 | new_size = hash->size * 2; |
40520c36 DW |
103 | |
104 | if (hash->max_size && new_size > hash->max_size) | |
105 | return; | |
106 | ||
d62a17ae | 107 | new_index = XCALLOC(MTYPE_HASH_INDEX, |
e3b78da8 | 108 | sizeof(struct hash_bucket *) * new_size); |
97c84db0 | 109 | |
d62a17ae | 110 | hash->stats.empty = new_size; |
6f6f0010 | 111 | |
d62a17ae | 112 | for (i = 0; i < hash->size; i++) |
113 | for (hb = hash->index[i]; hb; hb = hbnext) { | |
114 | unsigned int h = hb->key & (new_size - 1); | |
97c84db0 | 115 | |
d62a17ae | 116 | hbnext = hb->next; |
117 | hb->next = new_index[h]; | |
6f6f0010 | 118 | |
d62a17ae | 119 | int oldlen = hb->next ? hb->next->len : 0; |
120 | int newlen = oldlen + 1; | |
6f6f0010 | 121 | |
d62a17ae | 122 | if (newlen == 1) |
123 | hash->stats.empty--; | |
124 | else | |
125 | hb->next->len = 0; | |
6f6f0010 | 126 | |
d62a17ae | 127 | hb->len = newlen; |
6f6f0010 | 128 | |
d62a17ae | 129 | hash_update_ssq(hash, oldlen, newlen); |
6f6f0010 | 130 | |
d62a17ae | 131 | new_index[h] = hb; |
132 | } | |
97c84db0 | 133 | |
d62a17ae | 134 | /* Switch to new table */ |
135 | XFREE(MTYPE_HASH_INDEX, hash->index); | |
136 | hash->size = new_size; | |
137 | hash->index = new_index; | |
97c84db0 SH |
138 | } |
139 | ||
d62a17ae | 140 | void *hash_get(struct hash *hash, void *data, void *(*alloc_func)(void *)) |
718e3744 | 141 | { |
abf96a87 QY |
142 | tracepoint(frr_libfrr, hash_get, hash, data); |
143 | ||
d62a17ae | 144 | unsigned int key; |
145 | unsigned int index; | |
146 | void *newdata; | |
e3b78da8 | 147 | struct hash_bucket *bucket; |
d62a17ae | 148 | |
efb149d9 DS |
149 | if (!alloc_func && !hash->count) |
150 | return NULL; | |
151 | ||
d62a17ae | 152 | key = (*hash->hash_key)(data); |
153 | index = key & (hash->size - 1); | |
d62a17ae | 154 | |
e3b78da8 TB |
155 | for (bucket = hash->index[index]; bucket != NULL; |
156 | bucket = bucket->next) { | |
157 | if (bucket->key == key && (*hash->hash_cmp)(bucket->data, data)) | |
158 | return bucket->data; | |
97c84db0 SH |
159 | } |
160 | ||
d62a17ae | 161 | if (alloc_func) { |
162 | newdata = (*alloc_func)(data); | |
163 | if (newdata == NULL) | |
164 | return NULL; | |
6f6f0010 | 165 | |
bed7ad83 | 166 | if (HASH_THRESHOLD(hash->count + 1, hash->size)) { |
d62a17ae | 167 | hash_expand(hash); |
168 | index = key & (hash->size - 1); | |
169 | } | |
6f6f0010 | 170 | |
e3b78da8 TB |
171 | bucket = XCALLOC(MTYPE_HASH_BACKET, sizeof(struct hash_bucket)); |
172 | bucket->data = newdata; | |
173 | bucket->key = key; | |
174 | bucket->next = hash->index[index]; | |
175 | hash->index[index] = bucket; | |
d62a17ae | 176 | hash->count++; |
6f6f0010 | 177 | |
e3b78da8 | 178 | int oldlen = bucket->next ? bucket->next->len : 0; |
d62a17ae | 179 | int newlen = oldlen + 1; |
6f6f0010 | 180 | |
d62a17ae | 181 | if (newlen == 1) |
182 | hash->stats.empty--; | |
183 | else | |
e3b78da8 | 184 | bucket->next->len = 0; |
6f6f0010 | 185 | |
e3b78da8 | 186 | bucket->len = newlen; |
d62a17ae | 187 | |
188 | hash_update_ssq(hash, oldlen, newlen); | |
189 | ||
e3b78da8 | 190 | return bucket->data; |
d62a17ae | 191 | } |
192 | return NULL; | |
718e3744 | 193 | } |
194 | ||
d62a17ae | 195 | void *hash_lookup(struct hash *hash, void *data) |
718e3744 | 196 | { |
d62a17ae | 197 | return hash_get(hash, data, NULL); |
718e3744 | 198 | } |
199 | ||
d62a17ae | 200 | unsigned int string_hash_make(const char *str) |
6392aa83 | 201 | { |
d62a17ae | 202 | unsigned int hash = 0; |
6392aa83 | 203 | |
d62a17ae | 204 | while (*str) |
205 | hash = (hash * 33) ^ (unsigned int)*str++; | |
6392aa83 | 206 | |
d62a17ae | 207 | return hash; |
6392aa83 SH |
208 | } |
209 | ||
d62a17ae | 210 | void *hash_release(struct hash *hash, void *data) |
718e3744 | 211 | { |
abf96a87 | 212 | void *ret = NULL; |
d62a17ae | 213 | unsigned int key; |
214 | unsigned int index; | |
e3b78da8 TB |
215 | struct hash_bucket *bucket; |
216 | struct hash_bucket *pp; | |
d62a17ae | 217 | |
218 | key = (*hash->hash_key)(data); | |
219 | index = key & (hash->size - 1); | |
220 | ||
e3b78da8 TB |
221 | for (bucket = pp = hash->index[index]; bucket; bucket = bucket->next) { |
222 | if (bucket->key == key | |
223 | && (*hash->hash_cmp)(bucket->data, data)) { | |
d62a17ae | 224 | int oldlen = hash->index[index]->len; |
225 | int newlen = oldlen - 1; | |
226 | ||
e3b78da8 TB |
227 | if (bucket == pp) |
228 | hash->index[index] = bucket->next; | |
d62a17ae | 229 | else |
e3b78da8 | 230 | pp->next = bucket->next; |
d62a17ae | 231 | |
232 | if (hash->index[index]) | |
233 | hash->index[index]->len = newlen; | |
234 | else | |
235 | hash->stats.empty++; | |
236 | ||
237 | hash_update_ssq(hash, oldlen, newlen); | |
238 | ||
e3b78da8 TB |
239 | ret = bucket->data; |
240 | XFREE(MTYPE_HASH_BACKET, bucket); | |
d62a17ae | 241 | hash->count--; |
abf96a87 | 242 | break; |
d62a17ae | 243 | } |
e3b78da8 | 244 | pp = bucket; |
718e3744 | 245 | } |
abf96a87 QY |
246 | |
247 | tracepoint(frr_libfrr, hash_release, hash, data, ret); | |
248 | ||
249 | return ret; | |
718e3744 | 250 | } |
251 | ||
e3b78da8 | 252 | void hash_iterate(struct hash *hash, void (*func)(struct hash_bucket *, void *), |
d62a17ae | 253 | void *arg) |
718e3744 | 254 | { |
d62a17ae | 255 | unsigned int i; |
e3b78da8 TB |
256 | struct hash_bucket *hb; |
257 | struct hash_bucket *hbnext; | |
d62a17ae | 258 | |
df66eb2e | 259 | for (i = 0; i < hash->size; i++) |
d62a17ae | 260 | for (hb = hash->index[i]; hb; hb = hbnext) { |
e3b78da8 | 261 | /* get pointer to next hash bucket here, in case (*func) |
d62a17ae | 262 | * decides to delete hb by calling hash_release |
263 | */ | |
264 | hbnext = hb->next; | |
265 | (*func)(hb, arg); | |
266 | } | |
718e3744 | 267 | } |
268 | ||
e3b78da8 | 269 | void hash_walk(struct hash *hash, int (*func)(struct hash_bucket *, void *), |
d62a17ae | 270 | void *arg) |
3f9c7369 | 271 | { |
d62a17ae | 272 | unsigned int i; |
e3b78da8 TB |
273 | struct hash_bucket *hb; |
274 | struct hash_bucket *hbnext; | |
d62a17ae | 275 | int ret = HASHWALK_CONTINUE; |
276 | ||
277 | for (i = 0; i < hash->size; i++) { | |
278 | for (hb = hash->index[i]; hb; hb = hbnext) { | |
e3b78da8 | 279 | /* get pointer to next hash bucket here, in case (*func) |
d62a17ae | 280 | * decides to delete hb by calling hash_release |
281 | */ | |
282 | hbnext = hb->next; | |
283 | ret = (*func)(hb, arg); | |
284 | if (ret == HASHWALK_ABORT) | |
285 | return; | |
286 | } | |
3f9c7369 | 287 | } |
3f9c7369 DS |
288 | } |
289 | ||
d62a17ae | 290 | void hash_clean(struct hash *hash, void (*free_func)(void *)) |
718e3744 | 291 | { |
d62a17ae | 292 | unsigned int i; |
e3b78da8 TB |
293 | struct hash_bucket *hb; |
294 | struct hash_bucket *next; | |
718e3744 | 295 | |
d62a17ae | 296 | for (i = 0; i < hash->size; i++) { |
297 | for (hb = hash->index[i]; hb; hb = next) { | |
298 | next = hb->next; | |
299 | ||
300 | if (free_func) | |
301 | (*free_func)(hb->data); | |
718e3744 | 302 | |
d62a17ae | 303 | XFREE(MTYPE_HASH_BACKET, hb); |
304 | hash->count--; | |
305 | } | |
306 | hash->index[i] = NULL; | |
718e3744 | 307 | } |
6f6f0010 | 308 | |
d62a17ae | 309 | hash->stats.ssq = 0; |
310 | hash->stats.empty = hash->size; | |
718e3744 | 311 | } |
312 | ||
e3b78da8 | 313 | static void hash_to_list_iter(struct hash_bucket *hb, void *arg) |
91f10370 QY |
314 | { |
315 | struct list *list = arg; | |
316 | ||
317 | listnode_add(list, hb->data); | |
318 | } | |
319 | ||
320 | struct list *hash_to_list(struct hash *hash) | |
321 | { | |
322 | struct list *list = list_new(); | |
323 | ||
324 | hash_iterate(hash, hash_to_list_iter, list); | |
325 | return list; | |
326 | } | |
327 | ||
d62a17ae | 328 | void hash_free(struct hash *hash) |
718e3744 | 329 | { |
00dffa8c | 330 | frr_with_mutex(&_hashes_mtx) { |
d62a17ae | 331 | if (_hashes) { |
332 | listnode_delete(_hashes, hash); | |
333 | if (_hashes->count == 0) { | |
6a154c88 | 334 | list_delete(&_hashes); |
d62a17ae | 335 | } |
336 | } | |
337 | } | |
d62a17ae | 338 | |
0a22ddfb | 339 | XFREE(MTYPE_HASH, hash->name); |
d62a17ae | 340 | |
341 | XFREE(MTYPE_HASH_INDEX, hash->index); | |
342 | XFREE(MTYPE_HASH, hash); | |
4db0cff1 QY |
343 | } |
344 | ||
6f6f0010 QY |
345 | |
346 | /* CLI commands ------------------------------------------------------------ */ | |
4db0cff1 | 347 | |
40818cec DL |
348 | DEFUN_NOSH(show_hash_stats, |
349 | show_hash_stats_cmd, | |
350 | "show debugging hashtable [statistics]", | |
351 | SHOW_STR | |
352 | DEBUG_STR | |
353 | "Statistics about hash tables\n" | |
354 | "Statistics about hash tables\n") | |
4db0cff1 | 355 | { |
d62a17ae | 356 | struct hash *h; |
357 | struct listnode *ln; | |
358 | struct ttable *tt = ttable_new(&ttable_styles[TTSTYLE_BLANK]); | |
359 | ||
360 | ttable_add_row(tt, "Hash table|Buckets|Entries|Empty|LF|SD|FLF|SD"); | |
361 | tt->style.cell.lpad = 2; | |
362 | tt->style.cell.rpad = 1; | |
363 | tt->style.corner = '+'; | |
364 | ttable_restyle(tt); | |
365 | ttable_rowseps(tt, 0, BOTTOM, true, '-'); | |
366 | ||
367 | /* Summary statistics calculated are: | |
368 | * | |
c7d3895e CF |
369 | * - Load factor: This is the number of elements in the table divided |
370 | * by the number of buckets. Since this hash table implementation | |
371 | * uses chaining, this value can be greater than 1. | |
372 | * This number provides information on how 'full' the table is, but | |
373 | * does not provide information on how evenly distributed the | |
374 | * elements are. | |
375 | * Notably, a load factor >= 1 does not imply that every bucket has | |
376 | * an element; with a pathological hash function, all elements could | |
377 | * be in a single bucket. | |
d62a17ae | 378 | * |
379 | * - Full load factor: this is the number of elements in the table | |
c7d3895e | 380 | * divided by the number of buckets that have some elements in them. |
d62a17ae | 381 | * |
382 | * - Std. Dev.: This is the standard deviation calculated from the | |
c7d3895e CF |
383 | * relevant load factor. If the load factor is the mean of number of |
384 | * elements per bucket, the standard deviation measures how much any | |
385 | * particular bucket is likely to deviate from the mean. | |
386 | * As a rule of thumb this number should be less than 2, and ideally | |
387 | * <= 1 for optimal performance. A number larger than 3 generally | |
388 | * indicates a poor hash function. | |
d62a17ae | 389 | */ |
390 | ||
391 | double lf; // load factor | |
392 | double flf; // full load factor | |
393 | double var; // overall variance | |
394 | double fvar; // full variance | |
395 | double stdv; // overall stddev | |
396 | double fstdv; // full stddev | |
397 | ||
398 | long double x2; // h->count ^ 2 | |
399 | long double ldc; // (long double) h->count | |
400 | long double full; // h->size - h->stats.empty | |
401 | long double ssq; // ssq casted to long double | |
402 | ||
403 | pthread_mutex_lock(&_hashes_mtx); | |
404 | if (!_hashes) { | |
405 | pthread_mutex_unlock(&_hashes_mtx); | |
44f12f20 | 406 | ttable_del(tt); |
d62a17ae | 407 | vty_out(vty, "No hash tables in use.\n"); |
408 | return CMD_SUCCESS; | |
409 | } | |
410 | ||
411 | for (ALL_LIST_ELEMENTS_RO(_hashes, ln, h)) { | |
412 | if (!h->name) | |
413 | continue; | |
414 | ||
415 | ssq = (long double)h->stats.ssq; | |
61b9e9d6 | 416 | x2 = h->count * h->count; |
d62a17ae | 417 | ldc = (long double)h->count; |
418 | full = h->size - h->stats.empty; | |
419 | lf = h->count / (double)h->size; | |
420 | flf = full ? h->count / (double)(full) : 0; | |
421 | var = ldc ? (1.0 / ldc) * (ssq - x2 / ldc) : 0; | |
422 | fvar = full ? (1.0 / full) * (ssq - x2 / full) : 0; | |
423 | var = (var < .0001) ? 0 : var; | |
424 | fvar = (fvar < .0001) ? 0 : fvar; | |
425 | stdv = sqrt(var); | |
426 | fstdv = sqrt(fvar); | |
427 | ||
428 | ttable_add_row(tt, "%s|%d|%ld|%.0f%%|%.2lf|%.2lf|%.2lf|%.2lf", | |
429 | h->name, h->size, h->count, | |
430 | (h->stats.empty / (double)h->size) * 100, lf, | |
431 | stdv, flf, fstdv); | |
432 | } | |
433 | pthread_mutex_unlock(&_hashes_mtx); | |
434 | ||
435 | /* display header */ | |
436 | char header[] = "Showing hash table statistics for "; | |
437 | char underln[sizeof(header) + strlen(frr_protonameinst)]; | |
438 | memset(underln, '-', sizeof(underln)); | |
439 | underln[sizeof(underln) - 1] = '\0'; | |
440 | vty_out(vty, "%s%s\n", header, frr_protonameinst); | |
441 | vty_out(vty, "%s\n", underln); | |
442 | ||
443 | vty_out(vty, "# allocated: %d\n", _hashes->count); | |
444 | vty_out(vty, "# named: %d\n\n", tt->nrows - 1); | |
445 | ||
446 | if (tt->nrows > 1) { | |
447 | ttable_colseps(tt, 0, RIGHT, true, '|'); | |
448 | char *table = ttable_dump(tt, "\n"); | |
449 | vty_out(vty, "%s\n", table); | |
450 | XFREE(MTYPE_TMP, table); | |
451 | } else | |
452 | vty_out(vty, "No named hash tables to display.\n"); | |
453 | ||
454 | ttable_del(tt); | |
455 | ||
456 | return CMD_SUCCESS; | |
4db0cff1 QY |
457 | } |
458 | ||
4d762f26 | 459 | void hash_cmd_init(void) |
4db0cff1 | 460 | { |
d62a17ae | 461 | install_element(ENABLE_NODE, &show_hash_stats_cmd); |
4db0cff1 | 462 | } |