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 | ||
49 | #define BUCKET_SIZE_RESIZE_THRESHOLD 8 | |
2ed95849 | 50 | |
abc490a1 MD |
51 | #ifndef max |
52 | #define max(a, b) ((a) > (b) ? (a) : (b)) | |
53 | #endif | |
2ed95849 | 54 | |
395270b6 | 55 | struct rcu_table { |
abc490a1 | 56 | unsigned long size; /* always a power of 2 */ |
f9830efd | 57 | unsigned long resize_target; |
abc490a1 | 58 | struct rcu_head head; |
395270b6 MD |
59 | struct rcu_ht_node *tbl[0]; |
60 | }; | |
61 | ||
2ed95849 | 62 | struct rcu_ht { |
395270b6 | 63 | struct rcu_table *t; /* shared */ |
2ed95849 | 64 | ht_hash_fct hash_fct; |
abc490a1 | 65 | void *hashseed; |
464a1ec9 | 66 | pthread_mutex_t resize_mutex; /* resize mutex: add/del mutex */ |
abc490a1 MD |
67 | void (*ht_call_rcu)(struct rcu_head *head, |
68 | void (*func)(struct rcu_head *head)); | |
2ed95849 MD |
69 | }; |
70 | ||
abc490a1 MD |
71 | struct rcu_resize_work { |
72 | struct rcu_head head; | |
2ed95849 | 73 | struct rcu_ht *ht; |
abc490a1 | 74 | }; |
2ed95849 | 75 | |
abc490a1 MD |
76 | /* |
77 | * Algorithm to reverse bits in a word by lookup table, extended to | |
78 | * 64-bit words. | |
f9830efd | 79 | * Source: |
abc490a1 | 80 | * http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable |
f9830efd | 81 | * Originally from Public Domain. |
abc490a1 MD |
82 | */ |
83 | ||
84 | static const uint8_t BitReverseTable256[256] = | |
2ed95849 | 85 | { |
abc490a1 MD |
86 | #define R2(n) (n), (n) + 2*64, (n) + 1*64, (n) + 3*64 |
87 | #define R4(n) R2(n), R2((n) + 2*16), R2((n) + 1*16), R2((n) + 3*16) | |
88 | #define R6(n) R4(n), R4((n) + 2*4 ), R4((n) + 1*4 ), R4((n) + 3*4 ) | |
89 | R6(0), R6(2), R6(1), R6(3) | |
90 | }; | |
91 | #undef R2 | |
92 | #undef R4 | |
93 | #undef R6 | |
2ed95849 | 94 | |
abc490a1 MD |
95 | static |
96 | uint8_t bit_reverse_u8(uint8_t v) | |
97 | { | |
98 | return BitReverseTable256[v]; | |
99 | } | |
ab7d5fc6 | 100 | |
abc490a1 MD |
101 | static __attribute__((unused)) |
102 | uint32_t bit_reverse_u32(uint32_t v) | |
103 | { | |
104 | return ((uint32_t) bit_reverse_u8(v) << 24) | | |
105 | ((uint32_t) bit_reverse_u8(v >> 8) << 16) | | |
106 | ((uint32_t) bit_reverse_u8(v >> 16) << 8) | | |
107 | ((uint32_t) bit_reverse_u8(v >> 24)); | |
2ed95849 MD |
108 | } |
109 | ||
abc490a1 MD |
110 | static __attribute__((unused)) |
111 | uint64_t bit_reverse_u64(uint64_t v) | |
2ed95849 | 112 | { |
abc490a1 MD |
113 | return ((uint64_t) bit_reverse_u8(v) << 56) | |
114 | ((uint64_t) bit_reverse_u8(v >> 8) << 48) | | |
115 | ((uint64_t) bit_reverse_u8(v >> 16) << 40) | | |
116 | ((uint64_t) bit_reverse_u8(v >> 24) << 32) | | |
117 | ((uint64_t) bit_reverse_u8(v >> 32) << 24) | | |
118 | ((uint64_t) bit_reverse_u8(v >> 40) << 16) | | |
119 | ((uint64_t) bit_reverse_u8(v >> 48) << 8) | | |
120 | ((uint64_t) bit_reverse_u8(v >> 56)); | |
121 | } | |
122 | ||
123 | static | |
124 | unsigned long bit_reverse_ulong(unsigned long v) | |
125 | { | |
126 | #if (CAA_BITS_PER_LONG == 32) | |
127 | return bit_reverse_u32(v); | |
128 | #else | |
129 | return bit_reverse_u64(v); | |
130 | #endif | |
131 | } | |
132 | ||
f9830efd MD |
133 | /* |
134 | * Algorithm to find the log2 of a 32-bit unsigned integer. | |
135 | * source: http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogLookup | |
136 | * Originally from Public Domain. | |
137 | */ | |
138 | static const char LogTable256[256] = | |
139 | { | |
140 | #define LT(n) n, n, n, n, n, n, n, n, n, n, n, n, n, n, n, n | |
141 | -1, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, | |
142 | LT(4), LT(5), LT(5), LT(6), LT(6), LT(6), LT(6), | |
143 | LT(7), LT(7), LT(7), LT(7), LT(7), LT(7), LT(7), LT(7) | |
144 | }; | |
145 | ||
146 | uint32_t log2_u32(uint32_t v) | |
147 | { | |
148 | uint32_t t, tt; | |
149 | ||
150 | if ((tt = (v >> 16))) | |
151 | return (t = (tt >> 8)) | |
152 | ? 24 + LogTable256[t] | |
153 | : 16 + LogTable256[tt]; | |
154 | else | |
155 | return (t = (v >> 8)) | |
156 | ? 8 + LogTable256[t] | |
157 | : LogTable256[v]; | |
158 | } | |
159 | ||
160 | static | |
161 | void ht_resize_lazy(struct rcu_ht *ht, struct rcu_table *t, int growth); | |
162 | ||
163 | static | |
164 | void check_resize(struct rcu_ht *ht, struct rcu_table *t, | |
165 | uint32_t chain_len) | |
166 | { | |
167 | if (chain_len >= BUCKET_SIZE_RESIZE_THRESHOLD) | |
168 | ht_resize_lazy(ht, t, log2_u32(chain_len)); | |
169 | } | |
170 | ||
abc490a1 MD |
171 | static |
172 | struct rcu_ht_node *clear_flag(struct rcu_ht_node *node) | |
173 | { | |
174 | return (struct rcu_ht_node *) (((unsigned long) node) & ~0x1); | |
175 | } | |
176 | ||
177 | static | |
178 | int is_removed(struct rcu_ht_node *node) | |
179 | { | |
180 | return ((unsigned long) node) & 0x1; | |
181 | } | |
182 | ||
183 | static | |
184 | struct rcu_ht_node *flag_removed(struct rcu_ht_node *node) | |
185 | { | |
186 | return (struct rcu_ht_node *) (((unsigned long) node) | 0x1); | |
187 | } | |
188 | ||
189 | static | |
f9830efd | 190 | unsigned long _uatomic_max(unsigned long *ptr, unsigned long v) |
abc490a1 MD |
191 | { |
192 | unsigned long old1, old2; | |
193 | ||
194 | old1 = uatomic_read(ptr); | |
195 | do { | |
196 | old2 = old1; | |
197 | if (old2 >= v) | |
f9830efd | 198 | return old2; |
abc490a1 | 199 | } while ((old1 = uatomic_cmpxchg(ptr, old2, v)) != old2); |
f9830efd | 200 | return v; |
abc490a1 MD |
201 | } |
202 | ||
203 | static | |
f000907d | 204 | void _ht_add(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node) |
abc490a1 MD |
205 | { |
206 | struct rcu_ht_node *iter_prev = NULL, *iter = NULL; | |
207 | ||
f000907d MD |
208 | if (!t->size) |
209 | return; | |
abc490a1 | 210 | for (;;) { |
f9830efd | 211 | uint32_t chain_len = 0; |
abc490a1 MD |
212 | |
213 | iter_prev = rcu_dereference(t->tbl[node->hash & (t->size - 1)]); | |
214 | assert(iter_prev); | |
215 | assert(iter_prev->reverse_hash <= node->reverse_hash); | |
216 | for (;;) { | |
217 | iter = clear_flag(rcu_dereference(iter_prev->next)); | |
218 | if (unlikely(!iter)) | |
219 | break; | |
220 | if (iter->reverse_hash < node->reverse_hash) | |
221 | break; | |
222 | iter_prev = iter; | |
f000907d | 223 | check_resize(ht, t, ++chain_len); |
abc490a1 MD |
224 | } |
225 | /* add in iter_prev->next */ | |
226 | if (is_removed(iter)) | |
227 | continue; | |
f000907d | 228 | assert(node != iter); |
abc490a1 | 229 | node->next = iter; |
f000907d | 230 | assert(iter_prev != node); |
abc490a1 MD |
231 | if (uatomic_cmpxchg(&iter_prev->next, iter, node) != iter) |
232 | continue; | |
f000907d | 233 | break; |
464a1ec9 | 234 | } |
abc490a1 | 235 | } |
464a1ec9 | 236 | |
abc490a1 MD |
237 | static |
238 | int _ht_remove(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node) | |
239 | { | |
240 | struct rcu_ht_node *iter_prev, *iter, *next, *old; | |
241 | unsigned long chain_len; | |
242 | int found, ret = 0; | |
243 | int flagged = 0; | |
5e28c532 | 244 | |
abc490a1 MD |
245 | retry: |
246 | chain_len = 0; | |
247 | found = 0; | |
248 | iter_prev = rcu_dereference(t->tbl[node->hash & (t->size - 1)]); | |
249 | assert(iter_prev); | |
250 | assert(iter_prev->reverse_hash <= node->reverse_hash); | |
2ed95849 | 251 | for (;;) { |
abc490a1 MD |
252 | iter = clear_flag(rcu_dereference(iter_prev->next)); |
253 | if (unlikely(!iter)) | |
254 | break; | |
255 | if (iter->reverse_hash < node->reverse_hash) | |
256 | break; | |
257 | if (iter == node) { | |
258 | found = 1; | |
2ed95849 MD |
259 | break; |
260 | } | |
abc490a1 MD |
261 | iter_prev = iter; |
262 | } | |
263 | if (!found) { | |
264 | ret = -ENOENT; | |
265 | goto end; | |
266 | } | |
267 | next = rcu_dereference(iter->next); | |
268 | if (!flagged) { | |
269 | if (is_removed(next)) { | |
270 | ret = -ENOENT; | |
2ed95849 MD |
271 | goto end; |
272 | } | |
abc490a1 | 273 | /* set deletion flag */ |
f000907d MD |
274 | if ((old = uatomic_cmpxchg(&iter->next, next, |
275 | flag_removed(next))) != next) { | |
abc490a1 MD |
276 | if (old == flag_removed(next)) { |
277 | ret = -ENOENT; | |
278 | goto end; | |
279 | } else { | |
280 | goto retry; | |
281 | } | |
282 | } | |
283 | flagged = 1; | |
2ed95849 | 284 | } |
abc490a1 MD |
285 | /* |
286 | * Remove the element from the list. Retry if there has been a | |
287 | * concurrent add (there cannot be a concurrent delete, because | |
288 | * we won the deletion flag cmpxchg). | |
289 | */ | |
290 | if (uatomic_cmpxchg(&iter_prev->next, iter, clear_flag(next)) != iter) | |
291 | goto retry; | |
2ed95849 | 292 | end: |
2ed95849 | 293 | return ret; |
abc490a1 | 294 | } |
2ed95849 | 295 | |
abc490a1 MD |
296 | static |
297 | void init_table(struct rcu_ht *ht, struct rcu_table *t, | |
298 | unsigned long first, unsigned long len) | |
299 | { | |
300 | unsigned long i, end; | |
301 | ||
302 | end = first + len; | |
303 | for (i = first; i < end; i++) { | |
304 | /* Update table size when power of two */ | |
305 | if (i != 0 && !(i & (i - 1))) | |
306 | t->size = i; | |
307 | t->tbl[i] = calloc(1, sizeof(struct rcu_ht_node)); | |
308 | t->tbl[i]->dummy = 1; | |
309 | t->tbl[i]->hash = i; | |
310 | t->tbl[i]->reverse_hash = bit_reverse_ulong(i); | |
311 | _ht_add(ht, t, t->tbl[i]); | |
312 | } | |
f9830efd | 313 | t->resize_target = t->size = end; |
2ed95849 MD |
314 | } |
315 | ||
abc490a1 MD |
316 | struct rcu_ht *ht_new(ht_hash_fct hash_fct, |
317 | void *hashseed, | |
318 | unsigned long init_size, | |
319 | void (*ht_call_rcu)(struct rcu_head *head, | |
320 | void (*func)(struct rcu_head *head))) | |
321 | { | |
322 | struct rcu_ht *ht; | |
323 | ||
324 | ht = calloc(1, sizeof(struct rcu_ht)); | |
325 | ht->hash_fct = hash_fct; | |
326 | ht->hashseed = hashseed; | |
f000907d | 327 | ht->ht_call_rcu = ht_call_rcu; |
abc490a1 MD |
328 | /* this mutex should not nest in read-side C.S. */ |
329 | pthread_mutex_init(&ht->resize_mutex, NULL); | |
330 | ht->t = calloc(1, sizeof(struct rcu_table) | |
331 | + (max(init_size, 1) * sizeof(struct rcu_ht_node *))); | |
332 | ht->t->size = 0; | |
f000907d | 333 | pthread_mutex_lock(&ht->resize_mutex); |
abc490a1 | 334 | init_table(ht, ht->t, 0, max(init_size, 1)); |
f000907d | 335 | pthread_mutex_unlock(&ht->resize_mutex); |
abc490a1 MD |
336 | return ht; |
337 | } | |
338 | ||
339 | struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key) | |
2ed95849 | 340 | { |
395270b6 | 341 | struct rcu_table *t; |
abc490a1 MD |
342 | struct rcu_ht_node *node; |
343 | unsigned long hash, reverse_hash; | |
2ed95849 | 344 | |
abc490a1 MD |
345 | hash = ht->hash_fct(ht->hashseed, key); |
346 | reverse_hash = bit_reverse_ulong(hash); | |
464a1ec9 | 347 | |
395270b6 | 348 | t = rcu_dereference(ht->t); |
abc490a1 | 349 | node = rcu_dereference(t->tbl[hash & (t->size - 1)]); |
2ed95849 | 350 | for (;;) { |
abc490a1 MD |
351 | if (unlikely(!node)) |
352 | break; | |
353 | if (node->reverse_hash > reverse_hash) { | |
354 | node = NULL; | |
355 | break; | |
2ed95849 MD |
356 | } |
357 | if (node->key == key) { | |
abc490a1 MD |
358 | if (is_removed(rcu_dereference(node->next))) |
359 | node = NULL; | |
2ed95849 MD |
360 | break; |
361 | } | |
abc490a1 | 362 | node = clear_flag(rcu_dereference(node->next)); |
2ed95849 | 363 | } |
abc490a1 MD |
364 | return node; |
365 | } | |
e0ba718a | 366 | |
f000907d | 367 | void ht_add(struct rcu_ht *ht, struct rcu_ht_node *node) |
abc490a1 MD |
368 | { |
369 | struct rcu_table *t; | |
ab7d5fc6 | 370 | |
abc490a1 MD |
371 | node->hash = ht->hash_fct(ht->hashseed, node->key); |
372 | node->reverse_hash = bit_reverse_ulong((unsigned long) node->hash); | |
2ed95849 | 373 | |
abc490a1 | 374 | t = rcu_dereference(ht->t); |
f000907d | 375 | _ht_add(ht, t, node); |
2ed95849 MD |
376 | } |
377 | ||
abc490a1 | 378 | int ht_remove(struct rcu_ht *ht, struct rcu_ht_node *node) |
2ed95849 | 379 | { |
abc490a1 MD |
380 | struct rcu_table *t; |
381 | ||
382 | t = rcu_dereference(ht->t); | |
abc490a1 | 383 | return _ht_remove(ht, t, node); |
2ed95849 | 384 | } |
ab7d5fc6 | 385 | |
abc490a1 MD |
386 | static |
387 | int ht_delete_dummy(struct rcu_ht *ht) | |
674f7a69 | 388 | { |
395270b6 | 389 | struct rcu_table *t; |
abc490a1 MD |
390 | struct rcu_ht_node *node; |
391 | unsigned long i; | |
674f7a69 | 392 | |
abc490a1 MD |
393 | t = ht->t; |
394 | /* Check that the table is empty */ | |
395 | node = t->tbl[0]; | |
396 | do { | |
397 | if (!node->dummy) | |
398 | return -EPERM; | |
399 | node = node->next; | |
400 | } while (node); | |
401 | /* Internal sanity check: all nodes left should be dummy */ | |
395270b6 | 402 | for (i = 0; i < t->size; i++) { |
abc490a1 MD |
403 | assert(t->tbl[i]->dummy); |
404 | free(t->tbl[i]); | |
674f7a69 | 405 | } |
abc490a1 | 406 | return 0; |
674f7a69 MD |
407 | } |
408 | ||
409 | /* | |
410 | * Should only be called when no more concurrent readers nor writers can | |
411 | * possibly access the table. | |
412 | */ | |
5e28c532 | 413 | int ht_destroy(struct rcu_ht *ht) |
674f7a69 | 414 | { |
5e28c532 MD |
415 | int ret; |
416 | ||
abc490a1 MD |
417 | ret = ht_delete_dummy(ht); |
418 | if (ret) | |
419 | return ret; | |
395270b6 | 420 | free(ht->t); |
674f7a69 | 421 | free(ht); |
5e28c532 | 422 | return ret; |
674f7a69 MD |
423 | } |
424 | ||
abc490a1 MD |
425 | static |
426 | void ht_free_table_cb(struct rcu_head *head) | |
427 | { | |
428 | struct rcu_table *t = | |
429 | caa_container_of(head, struct rcu_table, head); | |
430 | free(t); | |
431 | } | |
432 | ||
433 | /* called with resize mutex held */ | |
434 | static | |
435 | void _do_ht_resize(struct rcu_ht *ht) | |
464a1ec9 | 436 | { |
abc490a1 | 437 | unsigned long new_size, old_size; |
395270b6 | 438 | struct rcu_table *new_t, *old_t; |
464a1ec9 | 439 | |
395270b6 MD |
440 | old_t = ht->t; |
441 | old_size = old_t->size; | |
464a1ec9 | 442 | |
f9830efd MD |
443 | new_size = CMM_LOAD_SHARED(old_t->resize_target); |
444 | dbg_printf("rculfhash: resize from %lu to %lu buckets\n", | |
445 | old_size, new_size); | |
abc490a1 | 446 | if (old_size == new_size) |
464a1ec9 | 447 | return; |
f000907d | 448 | new_t = malloc(sizeof(struct rcu_table) |
abc490a1 | 449 | + (new_size * sizeof(struct rcu_ht_node *))); |
f000907d MD |
450 | assert(new_size > old_size); |
451 | memcpy(&new_t->tbl, &old_t->tbl, | |
452 | old_size * sizeof(struct rcu_ht_node *)); | |
453 | init_table(ht, new_t, old_size, new_size - old_size); | |
454 | new_t->size = new_size; | |
455 | /* Changing table and size atomically wrt lookups */ | |
456 | rcu_assign_pointer(ht->t, new_t); | |
457 | ht->ht_call_rcu(&old_t->head, ht_free_table_cb); | |
464a1ec9 MD |
458 | } |
459 | ||
abc490a1 | 460 | static |
f9830efd MD |
461 | unsigned long resize_target_update(struct rcu_table *t, |
462 | int growth_order) | |
464a1ec9 | 463 | { |
f9830efd MD |
464 | return _uatomic_max(&t->resize_target, |
465 | t->size << growth_order); | |
464a1ec9 MD |
466 | } |
467 | ||
464a1ec9 MD |
468 | void ht_resize(struct rcu_ht *ht, int growth) |
469 | { | |
f9830efd MD |
470 | struct rcu_table *t = rcu_dereference(ht->t); |
471 | unsigned long target_size; | |
472 | ||
473 | target_size = resize_target_update(t, growth); | |
474 | if (t->size < target_size) { | |
475 | pthread_mutex_lock(&ht->resize_mutex); | |
476 | _do_ht_resize(ht); | |
477 | pthread_mutex_unlock(&ht->resize_mutex); | |
478 | } | |
abc490a1 | 479 | } |
464a1ec9 | 480 | |
abc490a1 MD |
481 | static |
482 | void do_resize_cb(struct rcu_head *head) | |
483 | { | |
484 | struct rcu_resize_work *work = | |
485 | caa_container_of(head, struct rcu_resize_work, head); | |
486 | struct rcu_ht *ht = work->ht; | |
487 | ||
488 | pthread_mutex_lock(&ht->resize_mutex); | |
489 | _do_ht_resize(ht); | |
490 | pthread_mutex_unlock(&ht->resize_mutex); | |
491 | free(work); | |
464a1ec9 MD |
492 | } |
493 | ||
abc490a1 | 494 | static |
f000907d | 495 | void ht_resize_lazy(struct rcu_ht *ht, struct rcu_table *t, int growth) |
ab7d5fc6 | 496 | { |
abc490a1 | 497 | struct rcu_resize_work *work; |
f9830efd | 498 | unsigned long target_size; |
abc490a1 | 499 | |
f9830efd MD |
500 | target_size = resize_target_update(t, growth); |
501 | if (t->size < target_size) { | |
502 | work = malloc(sizeof(*work)); | |
503 | work->ht = ht; | |
504 | ht->ht_call_rcu(&work->head, do_resize_cb); | |
505 | } | |
ab7d5fc6 | 506 | } |