Commit | Line | Data |
---|---|---|
5e28c532 | 1 | /* |
abc490a1 MD |
2 | * rculfhash.c |
3 | * | |
4 | * Userspace RCU library - Lock-Free Expandable RCU Hash Table | |
5 | * | |
6 | * Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
7 | * | |
8 | * This library is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU Lesser General Public | |
10 | * License as published by the Free Software Foundation; either | |
11 | * version 2.1 of the License, or (at your option) any later version. | |
12 | * | |
13 | * This library is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * Lesser General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU Lesser General Public | |
19 | * License along with this library; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
5e28c532 MD |
21 | */ |
22 | ||
2ed95849 MD |
23 | #define _LGPL_SOURCE |
24 | #include <stdlib.h> | |
e0ba718a MD |
25 | #include <errno.h> |
26 | #include <assert.h> | |
27 | #include <stdio.h> | |
abc490a1 | 28 | #include <stdint.h> |
f000907d | 29 | #include <string.h> |
e0ba718a | 30 | |
2ed95849 | 31 | #include <urcu.h> |
abc490a1 | 32 | #include <urcu-call-rcu.h> |
a42cc659 MD |
33 | #include <urcu/arch.h> |
34 | #include <urcu/uatomic.h> | |
674f7a69 | 35 | #include <urcu/jhash.h> |
a42cc659 | 36 | #include <urcu/compiler.h> |
abc490a1 | 37 | #include <urcu/rculfhash.h> |
5e28c532 | 38 | #include <stdio.h> |
464a1ec9 | 39 | #include <pthread.h> |
44395fb7 | 40 | |
f9830efd MD |
41 | #define DEBUG /* Test */ |
42 | ||
43 | #ifdef DEBUG | |
44 | #define dbg_printf(args...) printf(args) | |
45 | #else | |
46 | #define dbg_printf(args...) | |
47 | #endif | |
48 | ||
65e8e729 MD |
49 | #define CHAIN_LEN_TARGET 1 |
50 | #define CHAIN_LEN_RESIZE_THRESHOLD 2 | |
2ed95849 | 51 | |
abc490a1 MD |
52 | #ifndef max |
53 | #define max(a, b) ((a) > (b) ? (a) : (b)) | |
54 | #endif | |
2ed95849 | 55 | |
395270b6 | 56 | struct rcu_table { |
abc490a1 | 57 | unsigned long size; /* always a power of 2 */ |
f9830efd | 58 | unsigned long resize_target; |
11519af6 | 59 | int resize_initiated; |
abc490a1 | 60 | struct rcu_head head; |
395270b6 MD |
61 | struct rcu_ht_node *tbl[0]; |
62 | }; | |
63 | ||
2ed95849 | 64 | struct rcu_ht { |
395270b6 | 65 | struct rcu_table *t; /* shared */ |
2ed95849 | 66 | ht_hash_fct hash_fct; |
732ad076 MD |
67 | ht_compare_fct compare_fct; |
68 | unsigned long hash_seed; | |
464a1ec9 | 69 | pthread_mutex_t resize_mutex; /* resize mutex: add/del mutex */ |
abc490a1 MD |
70 | void (*ht_call_rcu)(struct rcu_head *head, |
71 | void (*func)(struct rcu_head *head)); | |
2ed95849 MD |
72 | }; |
73 | ||
abc490a1 MD |
74 | struct rcu_resize_work { |
75 | struct rcu_head head; | |
2ed95849 | 76 | struct rcu_ht *ht; |
abc490a1 | 77 | }; |
2ed95849 | 78 | |
abc490a1 MD |
79 | /* |
80 | * Algorithm to reverse bits in a word by lookup table, extended to | |
81 | * 64-bit words. | |
f9830efd | 82 | * Source: |
abc490a1 | 83 | * http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable |
f9830efd | 84 | * Originally from Public Domain. |
abc490a1 MD |
85 | */ |
86 | ||
87 | static const uint8_t BitReverseTable256[256] = | |
2ed95849 | 88 | { |
abc490a1 MD |
89 | #define R2(n) (n), (n) + 2*64, (n) + 1*64, (n) + 3*64 |
90 | #define R4(n) R2(n), R2((n) + 2*16), R2((n) + 1*16), R2((n) + 3*16) | |
91 | #define R6(n) R4(n), R4((n) + 2*4 ), R4((n) + 1*4 ), R4((n) + 3*4 ) | |
92 | R6(0), R6(2), R6(1), R6(3) | |
93 | }; | |
94 | #undef R2 | |
95 | #undef R4 | |
96 | #undef R6 | |
2ed95849 | 97 | |
abc490a1 MD |
98 | static |
99 | uint8_t bit_reverse_u8(uint8_t v) | |
100 | { | |
101 | return BitReverseTable256[v]; | |
102 | } | |
ab7d5fc6 | 103 | |
abc490a1 MD |
104 | static __attribute__((unused)) |
105 | uint32_t bit_reverse_u32(uint32_t v) | |
106 | { | |
107 | return ((uint32_t) bit_reverse_u8(v) << 24) | | |
108 | ((uint32_t) bit_reverse_u8(v >> 8) << 16) | | |
109 | ((uint32_t) bit_reverse_u8(v >> 16) << 8) | | |
110 | ((uint32_t) bit_reverse_u8(v >> 24)); | |
2ed95849 MD |
111 | } |
112 | ||
abc490a1 MD |
113 | static __attribute__((unused)) |
114 | uint64_t bit_reverse_u64(uint64_t v) | |
2ed95849 | 115 | { |
abc490a1 MD |
116 | return ((uint64_t) bit_reverse_u8(v) << 56) | |
117 | ((uint64_t) bit_reverse_u8(v >> 8) << 48) | | |
118 | ((uint64_t) bit_reverse_u8(v >> 16) << 40) | | |
119 | ((uint64_t) bit_reverse_u8(v >> 24) << 32) | | |
120 | ((uint64_t) bit_reverse_u8(v >> 32) << 24) | | |
121 | ((uint64_t) bit_reverse_u8(v >> 40) << 16) | | |
122 | ((uint64_t) bit_reverse_u8(v >> 48) << 8) | | |
123 | ((uint64_t) bit_reverse_u8(v >> 56)); | |
124 | } | |
125 | ||
126 | static | |
127 | unsigned long bit_reverse_ulong(unsigned long v) | |
128 | { | |
129 | #if (CAA_BITS_PER_LONG == 32) | |
130 | return bit_reverse_u32(v); | |
131 | #else | |
132 | return bit_reverse_u64(v); | |
133 | #endif | |
134 | } | |
135 | ||
f9830efd MD |
136 | /* |
137 | * Algorithm to find the log2 of a 32-bit unsigned integer. | |
138 | * source: http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogLookup | |
139 | * Originally from Public Domain. | |
140 | */ | |
141 | static const char LogTable256[256] = | |
142 | { | |
143 | #define LT(n) n, n, n, n, n, n, n, n, n, n, n, n, n, n, n, n | |
144 | -1, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, | |
145 | LT(4), LT(5), LT(5), LT(6), LT(6), LT(6), LT(6), | |
146 | LT(7), LT(7), LT(7), LT(7), LT(7), LT(7), LT(7), LT(7) | |
147 | }; | |
148 | ||
149 | uint32_t log2_u32(uint32_t v) | |
150 | { | |
151 | uint32_t t, tt; | |
152 | ||
153 | if ((tt = (v >> 16))) | |
154 | return (t = (tt >> 8)) | |
155 | ? 24 + LogTable256[t] | |
156 | : 16 + LogTable256[tt]; | |
157 | else | |
158 | return (t = (v >> 8)) | |
159 | ? 8 + LogTable256[t] | |
160 | : LogTable256[v]; | |
161 | } | |
162 | ||
163 | static | |
164 | void ht_resize_lazy(struct rcu_ht *ht, struct rcu_table *t, int growth); | |
165 | ||
166 | static | |
167 | void check_resize(struct rcu_ht *ht, struct rcu_table *t, | |
168 | uint32_t chain_len) | |
169 | { | |
3390d470 MD |
170 | if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD) |
171 | ht_resize_lazy(ht, t, | |
65e8e729 | 172 | log2_u32(chain_len - CHAIN_LEN_TARGET - 1)); |
f9830efd MD |
173 | } |
174 | ||
abc490a1 MD |
175 | static |
176 | struct rcu_ht_node *clear_flag(struct rcu_ht_node *node) | |
177 | { | |
178 | return (struct rcu_ht_node *) (((unsigned long) node) & ~0x1); | |
179 | } | |
180 | ||
181 | static | |
182 | int is_removed(struct rcu_ht_node *node) | |
183 | { | |
184 | return ((unsigned long) node) & 0x1; | |
185 | } | |
186 | ||
187 | static | |
188 | struct rcu_ht_node *flag_removed(struct rcu_ht_node *node) | |
189 | { | |
190 | return (struct rcu_ht_node *) (((unsigned long) node) | 0x1); | |
191 | } | |
192 | ||
193 | static | |
f9830efd | 194 | unsigned long _uatomic_max(unsigned long *ptr, unsigned long v) |
abc490a1 MD |
195 | { |
196 | unsigned long old1, old2; | |
197 | ||
198 | old1 = uatomic_read(ptr); | |
199 | do { | |
200 | old2 = old1; | |
201 | if (old2 >= v) | |
f9830efd | 202 | return old2; |
abc490a1 | 203 | } while ((old1 = uatomic_cmpxchg(ptr, old2, v)) != old2); |
f9830efd | 204 | return v; |
abc490a1 MD |
205 | } |
206 | ||
207 | static | |
f000907d | 208 | void _ht_add(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node) |
abc490a1 | 209 | { |
11519af6 | 210 | struct rcu_ht_node *iter_prev, *iter, *iter_prev_next, *next; |
abc490a1 | 211 | |
f000907d MD |
212 | if (!t->size) |
213 | return; | |
abc490a1 | 214 | for (;;) { |
f9830efd | 215 | uint32_t chain_len = 0; |
abc490a1 | 216 | |
11519af6 MD |
217 | /* |
218 | * iter_prev points to the non-removed node prior to the | |
219 | * insert location. | |
220 | * iter iterates until it finds the next non-removed | |
221 | * node. | |
222 | */ | |
abc490a1 | 223 | iter_prev = rcu_dereference(t->tbl[node->hash & (t->size - 1)]); |
11519af6 MD |
224 | /* We can always skip the dummy node initially */ |
225 | iter_prev_next = next = rcu_dereference(iter_prev->next); | |
abc490a1 MD |
226 | assert(iter_prev); |
227 | assert(iter_prev->reverse_hash <= node->reverse_hash); | |
228 | for (;;) { | |
11519af6 MD |
229 | iter = next; |
230 | if (unlikely(!clear_flag(iter))) | |
abc490a1 | 231 | break; |
11519af6 MD |
232 | next = rcu_dereference(clear_flag(iter)->next); |
233 | if (unlikely(is_removed(next))) | |
234 | continue; | |
235 | if (clear_flag(iter)->reverse_hash > node->reverse_hash) | |
abc490a1 | 236 | break; |
11519af6 MD |
237 | /* Only account for identical reverse hash once */ |
238 | if (iter_prev->reverse_hash != clear_flag(iter)->reverse_hash) | |
239 | check_resize(ht, t, ++chain_len); | |
240 | iter_prev = clear_flag(iter); | |
241 | iter_prev_next = next; | |
abc490a1 | 242 | } |
f000907d | 243 | assert(node != iter); |
11519af6 | 244 | assert(!is_removed(iter_prev)); |
f000907d | 245 | assert(iter_prev != node); |
11519af6 MD |
246 | node->next = iter; |
247 | if (uatomic_cmpxchg(&iter_prev->next, iter_prev_next, | |
248 | node) != iter_prev_next) | |
abc490a1 | 249 | continue; |
11519af6 MD |
250 | else |
251 | break; | |
464a1ec9 | 252 | } |
abc490a1 | 253 | } |
464a1ec9 | 254 | |
abc490a1 MD |
255 | static |
256 | int _ht_remove(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node) | |
257 | { | |
11519af6 | 258 | struct rcu_ht_node *iter_prev, *iter, *iter_prev_next, *next, *old; |
abc490a1 | 259 | unsigned long chain_len; |
11519af6 | 260 | int found; |
abc490a1 | 261 | int flagged = 0; |
5e28c532 | 262 | |
abc490a1 MD |
263 | retry: |
264 | chain_len = 0; | |
265 | found = 0; | |
11519af6 MD |
266 | /* |
267 | * iter_prev points to the non-removed node prior to the remove | |
268 | * location. | |
269 | * node is the node to remove. | |
270 | */ | |
abc490a1 | 271 | iter_prev = rcu_dereference(t->tbl[node->hash & (t->size - 1)]); |
11519af6 MD |
272 | /* We can always skip the dummy node initially */ |
273 | iter_prev_next = next = rcu_dereference(iter_prev->next); | |
abc490a1 MD |
274 | assert(iter_prev); |
275 | assert(iter_prev->reverse_hash <= node->reverse_hash); | |
2ed95849 | 276 | for (;;) { |
11519af6 MD |
277 | iter = next; |
278 | if (unlikely(!clear_flag(iter))) | |
abc490a1 | 279 | break; |
11519af6 | 280 | next = rcu_dereference(clear_flag(iter)->next); |
abc490a1 MD |
281 | if (iter == node) { |
282 | found = 1; | |
2ed95849 MD |
283 | break; |
284 | } | |
11519af6 MD |
285 | if (unlikely(is_removed(next))) |
286 | continue; | |
287 | if (clear_flag(iter)->reverse_hash > node->reverse_hash) | |
288 | break; | |
289 | iter_prev = clear_flag(iter); | |
290 | iter_prev_next = next; | |
abc490a1 | 291 | } |
11519af6 | 292 | if (!found) |
abc490a1 | 293 | goto end; |
abc490a1 | 294 | if (!flagged) { |
11519af6 | 295 | if (is_removed(next)) |
2ed95849 | 296 | goto end; |
abc490a1 | 297 | /* set deletion flag */ |
f000907d MD |
298 | if ((old = uatomic_cmpxchg(&iter->next, next, |
299 | flag_removed(next))) != next) { | |
11519af6 | 300 | if (old == flag_removed(next)) |
abc490a1 | 301 | goto end; |
11519af6 | 302 | else |
abc490a1 | 303 | goto retry; |
abc490a1 MD |
304 | } |
305 | flagged = 1; | |
2ed95849 | 306 | } |
abc490a1 | 307 | /* |
98f969fc | 308 | * Remove the element from the list. |
11519af6 MD |
309 | * - Retry if there has been a concurrent add before us. |
310 | * - Retry if the prev node has been deleted (its next removed | |
311 | * flag would be set). | |
312 | * - There cannot be a concurrent delete for our position, because | |
313 | * we won the deletion flag cmpxchg. | |
314 | * - If there is a concurrent add or remove after us while our | |
315 | * removed flag is set, it will skip us and link directly after | |
316 | * the prior non-removed node before us. In this case, the | |
317 | * retry will not find the node in the list anymore. | |
abc490a1 | 318 | */ |
11519af6 MD |
319 | if (uatomic_cmpxchg(&iter_prev->next, iter_prev_next, |
320 | clear_flag(next)) != iter_prev_next) | |
abc490a1 | 321 | goto retry; |
2ed95849 | 322 | end: |
11519af6 MD |
323 | /* |
324 | * Only the flagging action indicated that we (and no other) | |
325 | * removed the node from the hash. | |
326 | */ | |
327 | if (flagged) | |
328 | return 0; | |
329 | else | |
330 | return -ENOENT; | |
abc490a1 | 331 | } |
2ed95849 | 332 | |
abc490a1 MD |
333 | static |
334 | void init_table(struct rcu_ht *ht, struct rcu_table *t, | |
335 | unsigned long first, unsigned long len) | |
336 | { | |
337 | unsigned long i, end; | |
338 | ||
339 | end = first + len; | |
340 | for (i = first; i < end; i++) { | |
341 | /* Update table size when power of two */ | |
342 | if (i != 0 && !(i & (i - 1))) | |
343 | t->size = i; | |
344 | t->tbl[i] = calloc(1, sizeof(struct rcu_ht_node)); | |
345 | t->tbl[i]->dummy = 1; | |
346 | t->tbl[i]->hash = i; | |
347 | t->tbl[i]->reverse_hash = bit_reverse_ulong(i); | |
348 | _ht_add(ht, t, t->tbl[i]); | |
349 | } | |
f9830efd | 350 | t->resize_target = t->size = end; |
11519af6 | 351 | t->resize_initiated = 0; |
2ed95849 MD |
352 | } |
353 | ||
abc490a1 | 354 | struct rcu_ht *ht_new(ht_hash_fct hash_fct, |
732ad076 MD |
355 | ht_compare_fct compare_fct, |
356 | unsigned long hash_seed, | |
abc490a1 MD |
357 | unsigned long init_size, |
358 | void (*ht_call_rcu)(struct rcu_head *head, | |
359 | void (*func)(struct rcu_head *head))) | |
360 | { | |
361 | struct rcu_ht *ht; | |
362 | ||
363 | ht = calloc(1, sizeof(struct rcu_ht)); | |
364 | ht->hash_fct = hash_fct; | |
732ad076 MD |
365 | ht->compare_fct = compare_fct; |
366 | ht->hash_seed = hash_seed; | |
f000907d | 367 | ht->ht_call_rcu = ht_call_rcu; |
abc490a1 MD |
368 | /* this mutex should not nest in read-side C.S. */ |
369 | pthread_mutex_init(&ht->resize_mutex, NULL); | |
370 | ht->t = calloc(1, sizeof(struct rcu_table) | |
371 | + (max(init_size, 1) * sizeof(struct rcu_ht_node *))); | |
372 | ht->t->size = 0; | |
f000907d | 373 | pthread_mutex_lock(&ht->resize_mutex); |
abc490a1 | 374 | init_table(ht, ht->t, 0, max(init_size, 1)); |
f000907d | 375 | pthread_mutex_unlock(&ht->resize_mutex); |
abc490a1 MD |
376 | return ht; |
377 | } | |
378 | ||
732ad076 | 379 | struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key, size_t key_len) |
2ed95849 | 380 | { |
395270b6 | 381 | struct rcu_table *t; |
abc490a1 MD |
382 | struct rcu_ht_node *node; |
383 | unsigned long hash, reverse_hash; | |
2ed95849 | 384 | |
732ad076 | 385 | hash = ht->hash_fct(key, key_len, ht->hash_seed); |
abc490a1 | 386 | reverse_hash = bit_reverse_ulong(hash); |
464a1ec9 | 387 | |
395270b6 | 388 | t = rcu_dereference(ht->t); |
abc490a1 | 389 | node = rcu_dereference(t->tbl[hash & (t->size - 1)]); |
2ed95849 | 390 | for (;;) { |
abc490a1 MD |
391 | if (unlikely(!node)) |
392 | break; | |
dd4505e0 | 393 | if (unlikely(node->reverse_hash > reverse_hash)) { |
abc490a1 MD |
394 | node = NULL; |
395 | break; | |
2ed95849 | 396 | } |
732ad076 | 397 | if (!ht->compare_fct(node->key, node->key_len, key, key_len)) { |
dd4505e0 | 398 | if (unlikely(is_removed(rcu_dereference(node->next)))) |
abc490a1 | 399 | node = NULL; |
2ed95849 MD |
400 | break; |
401 | } | |
abc490a1 | 402 | node = clear_flag(rcu_dereference(node->next)); |
2ed95849 | 403 | } |
abc490a1 MD |
404 | return node; |
405 | } | |
e0ba718a | 406 | |
f000907d | 407 | void ht_add(struct rcu_ht *ht, struct rcu_ht_node *node) |
abc490a1 MD |
408 | { |
409 | struct rcu_table *t; | |
ab7d5fc6 | 410 | |
732ad076 | 411 | node->hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed); |
abc490a1 | 412 | node->reverse_hash = bit_reverse_ulong((unsigned long) node->hash); |
2ed95849 | 413 | |
abc490a1 | 414 | t = rcu_dereference(ht->t); |
f000907d | 415 | _ht_add(ht, t, node); |
2ed95849 MD |
416 | } |
417 | ||
abc490a1 | 418 | int ht_remove(struct rcu_ht *ht, struct rcu_ht_node *node) |
2ed95849 | 419 | { |
abc490a1 MD |
420 | struct rcu_table *t; |
421 | ||
422 | t = rcu_dereference(ht->t); | |
abc490a1 | 423 | return _ht_remove(ht, t, node); |
2ed95849 | 424 | } |
ab7d5fc6 | 425 | |
abc490a1 MD |
426 | static |
427 | int ht_delete_dummy(struct rcu_ht *ht) | |
674f7a69 | 428 | { |
395270b6 | 429 | struct rcu_table *t; |
abc490a1 MD |
430 | struct rcu_ht_node *node; |
431 | unsigned long i; | |
674f7a69 | 432 | |
abc490a1 MD |
433 | t = ht->t; |
434 | /* Check that the table is empty */ | |
435 | node = t->tbl[0]; | |
436 | do { | |
437 | if (!node->dummy) | |
438 | return -EPERM; | |
439 | node = node->next; | |
440 | } while (node); | |
441 | /* Internal sanity check: all nodes left should be dummy */ | |
395270b6 | 442 | for (i = 0; i < t->size; i++) { |
abc490a1 MD |
443 | assert(t->tbl[i]->dummy); |
444 | free(t->tbl[i]); | |
674f7a69 | 445 | } |
abc490a1 | 446 | return 0; |
674f7a69 MD |
447 | } |
448 | ||
449 | /* | |
450 | * Should only be called when no more concurrent readers nor writers can | |
451 | * possibly access the table. | |
452 | */ | |
5e28c532 | 453 | int ht_destroy(struct rcu_ht *ht) |
674f7a69 | 454 | { |
5e28c532 MD |
455 | int ret; |
456 | ||
abc490a1 MD |
457 | ret = ht_delete_dummy(ht); |
458 | if (ret) | |
459 | return ret; | |
395270b6 | 460 | free(ht->t); |
674f7a69 | 461 | free(ht); |
5e28c532 | 462 | return ret; |
674f7a69 MD |
463 | } |
464 | ||
abc490a1 MD |
465 | static |
466 | void ht_free_table_cb(struct rcu_head *head) | |
467 | { | |
468 | struct rcu_table *t = | |
469 | caa_container_of(head, struct rcu_table, head); | |
470 | free(t); | |
471 | } | |
472 | ||
473 | /* called with resize mutex held */ | |
474 | static | |
475 | void _do_ht_resize(struct rcu_ht *ht) | |
464a1ec9 | 476 | { |
abc490a1 | 477 | unsigned long new_size, old_size; |
395270b6 | 478 | struct rcu_table *new_t, *old_t; |
464a1ec9 | 479 | |
395270b6 MD |
480 | old_t = ht->t; |
481 | old_size = old_t->size; | |
464a1ec9 | 482 | |
f9830efd MD |
483 | new_size = CMM_LOAD_SHARED(old_t->resize_target); |
484 | dbg_printf("rculfhash: resize from %lu to %lu buckets\n", | |
485 | old_size, new_size); | |
abc490a1 | 486 | if (old_size == new_size) |
464a1ec9 | 487 | return; |
f000907d | 488 | new_t = malloc(sizeof(struct rcu_table) |
abc490a1 | 489 | + (new_size * sizeof(struct rcu_ht_node *))); |
f000907d MD |
490 | assert(new_size > old_size); |
491 | memcpy(&new_t->tbl, &old_t->tbl, | |
492 | old_size * sizeof(struct rcu_ht_node *)); | |
493 | init_table(ht, new_t, old_size, new_size - old_size); | |
f000907d MD |
494 | /* Changing table and size atomically wrt lookups */ |
495 | rcu_assign_pointer(ht->t, new_t); | |
496 | ht->ht_call_rcu(&old_t->head, ht_free_table_cb); | |
464a1ec9 MD |
497 | } |
498 | ||
abc490a1 | 499 | static |
f9830efd MD |
500 | unsigned long resize_target_update(struct rcu_table *t, |
501 | int growth_order) | |
464a1ec9 | 502 | { |
f9830efd MD |
503 | return _uatomic_max(&t->resize_target, |
504 | t->size << growth_order); | |
464a1ec9 MD |
505 | } |
506 | ||
464a1ec9 MD |
507 | void ht_resize(struct rcu_ht *ht, int growth) |
508 | { | |
f9830efd MD |
509 | struct rcu_table *t = rcu_dereference(ht->t); |
510 | unsigned long target_size; | |
511 | ||
512 | target_size = resize_target_update(t, growth); | |
513 | if (t->size < target_size) { | |
11519af6 | 514 | CMM_STORE_SHARED(t->resize_initiated, 1); |
f9830efd MD |
515 | pthread_mutex_lock(&ht->resize_mutex); |
516 | _do_ht_resize(ht); | |
517 | pthread_mutex_unlock(&ht->resize_mutex); | |
518 | } | |
abc490a1 | 519 | } |
464a1ec9 | 520 | |
abc490a1 MD |
521 | static |
522 | void do_resize_cb(struct rcu_head *head) | |
523 | { | |
524 | struct rcu_resize_work *work = | |
525 | caa_container_of(head, struct rcu_resize_work, head); | |
526 | struct rcu_ht *ht = work->ht; | |
527 | ||
528 | pthread_mutex_lock(&ht->resize_mutex); | |
529 | _do_ht_resize(ht); | |
530 | pthread_mutex_unlock(&ht->resize_mutex); | |
531 | free(work); | |
464a1ec9 MD |
532 | } |
533 | ||
abc490a1 | 534 | static |
f000907d | 535 | void ht_resize_lazy(struct rcu_ht *ht, struct rcu_table *t, int growth) |
ab7d5fc6 | 536 | { |
abc490a1 | 537 | struct rcu_resize_work *work; |
f9830efd | 538 | unsigned long target_size; |
abc490a1 | 539 | |
f9830efd | 540 | target_size = resize_target_update(t, growth); |
11519af6 | 541 | if (!CMM_LOAD_SHARED(t->resize_initiated) && t->size < target_size) { |
f9830efd MD |
542 | work = malloc(sizeof(*work)); |
543 | work->ht = ht; | |
544 | ht->ht_call_rcu(&work->head, do_resize_cb); | |
11519af6 | 545 | CMM_STORE_SHARED(t->resize_initiated, 1); |
f9830efd | 546 | } |
ab7d5fc6 | 547 | } |