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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 | * | |
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 | |
19 | */ | |
20 | ||
21 | #include <zebra.h> | |
22 | #include <math.h> | |
23 | ||
24 | #include "hash.h" | |
25 | #include "memory.h" | |
26 | #include "linklist.h" | |
27 | #include "termtable.h" | |
28 | #include "vty.h" | |
29 | #include "command.h" | |
30 | #include "libfrr.h" | |
31 | ||
32 | DEFINE_MTYPE(LIB, HASH, "Hash") | |
33 | DEFINE_MTYPE(LIB, HASH_BACKET, "Hash Bucket") | |
34 | DEFINE_MTYPE_STATIC(LIB, HASH_INDEX, "Hash Index") | |
35 | ||
36 | static pthread_mutex_t _hashes_mtx = PTHREAD_MUTEX_INITIALIZER; | |
37 | static struct list *_hashes; | |
38 | ||
39 | struct hash *hash_create_size(unsigned int size, | |
40 | unsigned int (*hash_key)(void *), | |
41 | bool (*hash_cmp)(const void *, const void *), | |
42 | const char *name) | |
43 | { | |
44 | struct hash *hash; | |
45 | ||
46 | assert((size & (size - 1)) == 0); | |
47 | hash = XCALLOC(MTYPE_HASH, sizeof(struct hash)); | |
48 | hash->index = | |
49 | XCALLOC(MTYPE_HASH_INDEX, sizeof(struct hash_bucket *) * size); | |
50 | hash->size = size; | |
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; | |
67 | } | |
68 | ||
69 | struct hash *hash_create(unsigned int (*hash_key)(void *), | |
70 | bool (*hash_cmp)(const void *, const void *), | |
71 | const char *name) | |
72 | { | |
73 | return hash_create_size(HASH_INITIAL_SIZE, hash_key, hash_cmp, name); | |
74 | } | |
75 | ||
76 | void *hash_alloc_intern(void *arg) | |
77 | { | |
78 | return arg; | |
79 | } | |
80 | ||
81 | #define hash_update_ssq(hz, old, new) \ | |
82 | atomic_fetch_add_explicit(&hz->stats.ssq, (new + old) * (new - old), \ | |
83 | memory_order_relaxed); | |
84 | ||
85 | /* Expand hash if the chain length exceeds the threshold. */ | |
86 | static void hash_expand(struct hash *hash) | |
87 | { | |
88 | unsigned int i, new_size; | |
89 | struct hash_bucket *hb, *hbnext, **new_index; | |
90 | ||
91 | new_size = hash->size * 2; | |
92 | ||
93 | if (hash->max_size && new_size > hash->max_size) | |
94 | return; | |
95 | ||
96 | new_index = XCALLOC(MTYPE_HASH_INDEX, | |
97 | sizeof(struct hash_bucket *) * new_size); | |
98 | ||
99 | hash->stats.empty = new_size; | |
100 | ||
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); | |
104 | ||
105 | hbnext = hb->next; | |
106 | hb->next = new_index[h]; | |
107 | ||
108 | int oldlen = hb->next ? hb->next->len : 0; | |
109 | int newlen = oldlen + 1; | |
110 | ||
111 | if (newlen == 1) | |
112 | hash->stats.empty--; | |
113 | else | |
114 | hb->next->len = 0; | |
115 | ||
116 | hb->len = newlen; | |
117 | ||
118 | hash_update_ssq(hash, oldlen, newlen); | |
119 | ||
120 | new_index[h] = hb; | |
121 | } | |
122 | ||
123 | /* Switch to new table */ | |
124 | XFREE(MTYPE_HASH_INDEX, hash->index); | |
125 | hash->size = new_size; | |
126 | hash->index = new_index; | |
127 | } | |
128 | ||
129 | void *hash_get(struct hash *hash, void *data, void *(*alloc_func)(void *)) | |
130 | { | |
131 | unsigned int key; | |
132 | unsigned int index; | |
133 | void *newdata; | |
134 | struct hash_bucket *bucket; | |
135 | ||
136 | if (!alloc_func && !hash->count) | |
137 | return NULL; | |
138 | ||
139 | key = (*hash->hash_key)(data); | |
140 | index = key & (hash->size - 1); | |
141 | ||
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; | |
146 | } | |
147 | ||
148 | if (alloc_func) { | |
149 | newdata = (*alloc_func)(data); | |
150 | if (newdata == NULL) | |
151 | return NULL; | |
152 | ||
153 | if (HASH_THRESHOLD(hash->count + 1, hash->size)) { | |
154 | hash_expand(hash); | |
155 | index = key & (hash->size - 1); | |
156 | } | |
157 | ||
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; | |
163 | hash->count++; | |
164 | ||
165 | int oldlen = bucket->next ? bucket->next->len : 0; | |
166 | int newlen = oldlen + 1; | |
167 | ||
168 | if (newlen == 1) | |
169 | hash->stats.empty--; | |
170 | else | |
171 | bucket->next->len = 0; | |
172 | ||
173 | bucket->len = newlen; | |
174 | ||
175 | hash_update_ssq(hash, oldlen, newlen); | |
176 | ||
177 | return bucket->data; | |
178 | } | |
179 | return NULL; | |
180 | } | |
181 | ||
182 | void *hash_lookup(struct hash *hash, void *data) | |
183 | { | |
184 | return hash_get(hash, data, NULL); | |
185 | } | |
186 | ||
187 | unsigned int string_hash_make(const char *str) | |
188 | { | |
189 | unsigned int hash = 0; | |
190 | ||
191 | while (*str) | |
192 | hash = (hash * 33) ^ (unsigned int)*str++; | |
193 | ||
194 | return hash; | |
195 | } | |
196 | ||
197 | void *hash_release(struct hash *hash, void *data) | |
198 | { | |
199 | void *ret; | |
200 | unsigned int key; | |
201 | unsigned int index; | |
202 | struct hash_bucket *bucket; | |
203 | struct hash_bucket *pp; | |
204 | ||
205 | key = (*hash->hash_key)(data); | |
206 | index = key & (hash->size - 1); | |
207 | ||
208 | for (bucket = pp = hash->index[index]; bucket; bucket = bucket->next) { | |
209 | if (bucket->key == key | |
210 | && (*hash->hash_cmp)(bucket->data, data)) { | |
211 | int oldlen = hash->index[index]->len; | |
212 | int newlen = oldlen - 1; | |
213 | ||
214 | if (bucket == pp) | |
215 | hash->index[index] = bucket->next; | |
216 | else | |
217 | pp->next = bucket->next; | |
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 | ||
226 | ret = bucket->data; | |
227 | XFREE(MTYPE_HASH_BACKET, bucket); | |
228 | hash->count--; | |
229 | return ret; | |
230 | } | |
231 | pp = bucket; | |
232 | } | |
233 | return NULL; | |
234 | } | |
235 | ||
236 | void hash_iterate(struct hash *hash, void (*func)(struct hash_bucket *, void *), | |
237 | void *arg) | |
238 | { | |
239 | unsigned int i; | |
240 | struct hash_bucket *hb; | |
241 | struct hash_bucket *hbnext; | |
242 | ||
243 | for (i = 0; i < hash->size; i++) | |
244 | for (hb = hash->index[i]; hb; hb = hbnext) { | |
245 | /* get pointer to next hash bucket here, in case (*func) | |
246 | * decides to delete hb by calling hash_release | |
247 | */ | |
248 | hbnext = hb->next; | |
249 | (*func)(hb, arg); | |
250 | } | |
251 | } | |
252 | ||
253 | void hash_walk(struct hash *hash, int (*func)(struct hash_bucket *, void *), | |
254 | void *arg) | |
255 | { | |
256 | unsigned int i; | |
257 | struct hash_bucket *hb; | |
258 | struct hash_bucket *hbnext; | |
259 | int ret = HASHWALK_CONTINUE; | |
260 | ||
261 | for (i = 0; i < hash->size; i++) { | |
262 | for (hb = hash->index[i]; hb; hb = hbnext) { | |
263 | /* get pointer to next hash bucket here, in case (*func) | |
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 | } | |
271 | } | |
272 | } | |
273 | ||
274 | void hash_clean(struct hash *hash, void (*free_func)(void *)) | |
275 | { | |
276 | unsigned int i; | |
277 | struct hash_bucket *hb; | |
278 | struct hash_bucket *next; | |
279 | ||
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); | |
286 | ||
287 | XFREE(MTYPE_HASH_BACKET, hb); | |
288 | hash->count--; | |
289 | } | |
290 | hash->index[i] = NULL; | |
291 | } | |
292 | ||
293 | hash->stats.ssq = 0; | |
294 | hash->stats.empty = hash->size; | |
295 | } | |
296 | ||
297 | static void hash_to_list_iter(struct hash_bucket *hb, void *arg) | |
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 | ||
312 | void hash_free(struct hash *hash) | |
313 | { | |
314 | pthread_mutex_lock(&_hashes_mtx); | |
315 | { | |
316 | if (_hashes) { | |
317 | listnode_delete(_hashes, hash); | |
318 | if (_hashes->count == 0) { | |
319 | list_delete(&_hashes); | |
320 | } | |
321 | } | |
322 | } | |
323 | pthread_mutex_unlock(&_hashes_mtx); | |
324 | ||
325 | XFREE(MTYPE_HASH, hash->name); | |
326 | ||
327 | XFREE(MTYPE_HASH_INDEX, hash->index); | |
328 | XFREE(MTYPE_HASH, hash); | |
329 | } | |
330 | ||
331 | ||
332 | /* CLI commands ------------------------------------------------------------ */ | |
333 | ||
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") | |
341 | { | |
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 | * | |
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. | |
364 | * | |
365 | * - Full load factor: this is the number of elements in the table | |
366 | * divided by the number of buckets that have some elements in them. | |
367 | * | |
368 | * - Std. Dev.: This is the standard deviation calculated from the | |
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. | |
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); | |
392 | ttable_del(tt); | |
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; | |
402 | x2 = h->count * h->count; | |
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; | |
443 | } | |
444 | ||
445 | void hash_cmd_init(void) | |
446 | { | |
447 | install_element(ENABLE_NODE, &show_hash_stats_cmd); | |
448 | } |