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> |
e0ba718a | 29 | |
2ed95849 | 30 | #include <urcu.h> |
abc490a1 | 31 | #include <urcu-call-rcu.h> |
a42cc659 MD |
32 | #include <urcu/arch.h> |
33 | #include <urcu/uatomic.h> | |
674f7a69 | 34 | #include <urcu/jhash.h> |
a42cc659 | 35 | #include <urcu/compiler.h> |
abc490a1 | 36 | #include <urcu/rculfhash.h> |
5e28c532 | 37 | #include <stdio.h> |
464a1ec9 | 38 | #include <pthread.h> |
44395fb7 | 39 | |
abc490a1 | 40 | #define BUCKET_SIZE_RESIZE_THRESHOLD 5 |
2ed95849 | 41 | |
abc490a1 MD |
42 | #ifndef max |
43 | #define max(a, b) ((a) > (b) ? (a) : (b)) | |
44 | #endif | |
2ed95849 | 45 | |
395270b6 | 46 | struct rcu_table { |
abc490a1 MD |
47 | unsigned long size; /* always a power of 2 */ |
48 | struct rcu_head head; | |
395270b6 MD |
49 | struct rcu_ht_node *tbl[0]; |
50 | }; | |
51 | ||
2ed95849 | 52 | struct rcu_ht { |
395270b6 | 53 | struct rcu_table *t; /* shared */ |
2ed95849 | 54 | ht_hash_fct hash_fct; |
abc490a1 | 55 | void *hashseed; |
464a1ec9 | 56 | pthread_mutex_t resize_mutex; /* resize mutex: add/del mutex */ |
abc490a1 MD |
57 | unsigned long target_size; |
58 | void (*ht_call_rcu)(struct rcu_head *head, | |
59 | void (*func)(struct rcu_head *head)); | |
2ed95849 MD |
60 | }; |
61 | ||
abc490a1 MD |
62 | struct rcu_resize_work { |
63 | struct rcu_head head; | |
2ed95849 | 64 | struct rcu_ht *ht; |
abc490a1 | 65 | }; |
2ed95849 | 66 | |
abc490a1 MD |
67 | static |
68 | void ht_resize_lazy(struct rcu_ht *ht, int growth); | |
69 | ||
70 | static | |
71 | void check_resize(struct rcu_ht *ht, unsigned long chain_len) | |
72 | { | |
73 | if (chain_len >= BUCKET_SIZE_RESIZE_THRESHOLD) | |
74 | ht_resize_lazy(ht, chain_len / BUCKET_SIZE_RESIZE_THRESHOLD); | |
2ed95849 MD |
75 | } |
76 | ||
abc490a1 MD |
77 | /* |
78 | * Algorithm to reverse bits in a word by lookup table, extended to | |
79 | * 64-bit words. | |
80 | * ref. | |
81 | * http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable | |
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 | ||
133 | static | |
134 | struct rcu_ht_node *clear_flag(struct rcu_ht_node *node) | |
135 | { | |
136 | return (struct rcu_ht_node *) (((unsigned long) node) & ~0x1); | |
137 | } | |
138 | ||
139 | static | |
140 | int is_removed(struct rcu_ht_node *node) | |
141 | { | |
142 | return ((unsigned long) node) & 0x1; | |
143 | } | |
144 | ||
145 | static | |
146 | struct rcu_ht_node *flag_removed(struct rcu_ht_node *node) | |
147 | { | |
148 | return (struct rcu_ht_node *) (((unsigned long) node) | 0x1); | |
149 | } | |
150 | ||
151 | static | |
152 | void _uatomic_max(unsigned long *ptr, unsigned long v) | |
153 | { | |
154 | unsigned long old1, old2; | |
155 | ||
156 | old1 = uatomic_read(ptr); | |
157 | do { | |
158 | old2 = old1; | |
159 | if (old2 >= v) | |
160 | break; | |
161 | } while ((old1 = uatomic_cmpxchg(ptr, old2, v)) != old2); | |
162 | } | |
163 | ||
164 | static | |
165 | int _ht_add(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node) | |
166 | { | |
167 | struct rcu_ht_node *iter_prev = NULL, *iter = NULL; | |
168 | ||
169 | for (;;) { | |
170 | unsigned long chain_len = 0; | |
171 | ||
172 | iter_prev = rcu_dereference(t->tbl[node->hash & (t->size - 1)]); | |
173 | assert(iter_prev); | |
174 | assert(iter_prev->reverse_hash <= node->reverse_hash); | |
175 | for (;;) { | |
176 | iter = clear_flag(rcu_dereference(iter_prev->next)); | |
177 | if (unlikely(!iter)) | |
178 | break; | |
179 | if (iter->reverse_hash < node->reverse_hash) | |
180 | break; | |
181 | iter_prev = iter; | |
182 | check_resize(ht, ++chain_len); | |
183 | } | |
184 | /* add in iter_prev->next */ | |
185 | if (is_removed(iter)) | |
186 | continue; | |
187 | node->next = iter; | |
188 | if (uatomic_cmpxchg(&iter_prev->next, iter, node) != iter) | |
189 | continue; | |
464a1ec9 | 190 | } |
abc490a1 | 191 | } |
464a1ec9 | 192 | |
abc490a1 MD |
193 | static |
194 | int _ht_remove(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node) | |
195 | { | |
196 | struct rcu_ht_node *iter_prev, *iter, *next, *old; | |
197 | unsigned long chain_len; | |
198 | int found, ret = 0; | |
199 | int flagged = 0; | |
5e28c532 | 200 | |
abc490a1 MD |
201 | retry: |
202 | chain_len = 0; | |
203 | found = 0; | |
204 | iter_prev = rcu_dereference(t->tbl[node->hash & (t->size - 1)]); | |
205 | assert(iter_prev); | |
206 | assert(iter_prev->reverse_hash <= node->reverse_hash); | |
2ed95849 | 207 | for (;;) { |
abc490a1 MD |
208 | iter = clear_flag(rcu_dereference(iter_prev->next)); |
209 | if (unlikely(!iter)) | |
210 | break; | |
211 | if (iter->reverse_hash < node->reverse_hash) | |
212 | break; | |
213 | if (iter == node) { | |
214 | found = 1; | |
2ed95849 MD |
215 | break; |
216 | } | |
abc490a1 MD |
217 | iter_prev = iter; |
218 | } | |
219 | if (!found) { | |
220 | ret = -ENOENT; | |
221 | goto end; | |
222 | } | |
223 | next = rcu_dereference(iter->next); | |
224 | if (!flagged) { | |
225 | if (is_removed(next)) { | |
226 | ret = -ENOENT; | |
2ed95849 MD |
227 | goto end; |
228 | } | |
abc490a1 MD |
229 | /* set deletion flag */ |
230 | if ((old = uatomic_cmpxchg(&iter->next, next, flag_removed(next))) != next) { | |
231 | if (old == flag_removed(next)) { | |
232 | ret = -ENOENT; | |
233 | goto end; | |
234 | } else { | |
235 | goto retry; | |
236 | } | |
237 | } | |
238 | flagged = 1; | |
2ed95849 | 239 | } |
abc490a1 MD |
240 | /* |
241 | * Remove the element from the list. Retry if there has been a | |
242 | * concurrent add (there cannot be a concurrent delete, because | |
243 | * we won the deletion flag cmpxchg). | |
244 | */ | |
245 | if (uatomic_cmpxchg(&iter_prev->next, iter, clear_flag(next)) != iter) | |
246 | goto retry; | |
2ed95849 | 247 | end: |
2ed95849 | 248 | return ret; |
abc490a1 | 249 | } |
2ed95849 | 250 | |
abc490a1 MD |
251 | static |
252 | void init_table(struct rcu_ht *ht, struct rcu_table *t, | |
253 | unsigned long first, unsigned long len) | |
254 | { | |
255 | unsigned long i, end; | |
256 | ||
257 | end = first + len; | |
258 | for (i = first; i < end; i++) { | |
259 | /* Update table size when power of two */ | |
260 | if (i != 0 && !(i & (i - 1))) | |
261 | t->size = i; | |
262 | t->tbl[i] = calloc(1, sizeof(struct rcu_ht_node)); | |
263 | t->tbl[i]->dummy = 1; | |
264 | t->tbl[i]->hash = i; | |
265 | t->tbl[i]->reverse_hash = bit_reverse_ulong(i); | |
266 | _ht_add(ht, t, t->tbl[i]); | |
267 | } | |
268 | t->size = end; | |
2ed95849 MD |
269 | } |
270 | ||
abc490a1 MD |
271 | struct rcu_ht *ht_new(ht_hash_fct hash_fct, |
272 | void *hashseed, | |
273 | unsigned long init_size, | |
274 | void (*ht_call_rcu)(struct rcu_head *head, | |
275 | void (*func)(struct rcu_head *head))) | |
276 | { | |
277 | struct rcu_ht *ht; | |
278 | ||
279 | ht = calloc(1, sizeof(struct rcu_ht)); | |
280 | ht->hash_fct = hash_fct; | |
281 | ht->hashseed = hashseed; | |
282 | /* this mutex should not nest in read-side C.S. */ | |
283 | pthread_mutex_init(&ht->resize_mutex, NULL); | |
284 | ht->t = calloc(1, sizeof(struct rcu_table) | |
285 | + (max(init_size, 1) * sizeof(struct rcu_ht_node *))); | |
286 | ht->t->size = 0; | |
287 | init_table(ht, ht->t, 0, max(init_size, 1)); | |
288 | ht->target_size = ht->t->size; | |
289 | ht->ht_call_rcu = ht_call_rcu; | |
290 | return ht; | |
291 | } | |
292 | ||
293 | struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key) | |
2ed95849 | 294 | { |
395270b6 | 295 | struct rcu_table *t; |
abc490a1 MD |
296 | struct rcu_ht_node *node; |
297 | unsigned long hash, reverse_hash; | |
2ed95849 | 298 | |
abc490a1 MD |
299 | hash = ht->hash_fct(ht->hashseed, key); |
300 | reverse_hash = bit_reverse_ulong(hash); | |
464a1ec9 | 301 | |
395270b6 | 302 | t = rcu_dereference(ht->t); |
abc490a1 MD |
303 | cmm_smp_read_barrier_depends(); /* read t before size and table */ |
304 | node = rcu_dereference(t->tbl[hash & (t->size - 1)]); | |
2ed95849 | 305 | for (;;) { |
abc490a1 MD |
306 | if (unlikely(!node)) |
307 | break; | |
308 | if (node->reverse_hash > reverse_hash) { | |
309 | node = NULL; | |
310 | break; | |
2ed95849 MD |
311 | } |
312 | if (node->key == key) { | |
abc490a1 MD |
313 | if (is_removed(rcu_dereference(node->next))) |
314 | node = NULL; | |
2ed95849 MD |
315 | break; |
316 | } | |
abc490a1 | 317 | node = clear_flag(rcu_dereference(node->next)); |
2ed95849 | 318 | } |
abc490a1 MD |
319 | return node; |
320 | } | |
e0ba718a | 321 | |
abc490a1 MD |
322 | int ht_add(struct rcu_ht *ht, struct rcu_ht_node *node) |
323 | { | |
324 | struct rcu_table *t; | |
ab7d5fc6 | 325 | |
abc490a1 MD |
326 | node->hash = ht->hash_fct(ht->hashseed, node->key); |
327 | node->reverse_hash = bit_reverse_ulong((unsigned long) node->hash); | |
2ed95849 | 328 | |
abc490a1 MD |
329 | t = rcu_dereference(ht->t); |
330 | cmm_smp_read_barrier_depends(); /* read t before size and table */ | |
331 | return _ht_add(ht, t, node); | |
2ed95849 MD |
332 | } |
333 | ||
abc490a1 | 334 | int ht_remove(struct rcu_ht *ht, struct rcu_ht_node *node) |
2ed95849 | 335 | { |
abc490a1 MD |
336 | struct rcu_table *t; |
337 | ||
338 | t = rcu_dereference(ht->t); | |
339 | cmm_smp_read_barrier_depends(); /* read t before size and table */ | |
340 | return _ht_remove(ht, t, node); | |
2ed95849 | 341 | } |
ab7d5fc6 | 342 | |
abc490a1 MD |
343 | static |
344 | int ht_delete_dummy(struct rcu_ht *ht) | |
674f7a69 | 345 | { |
395270b6 | 346 | struct rcu_table *t; |
abc490a1 MD |
347 | struct rcu_ht_node *node; |
348 | unsigned long i; | |
674f7a69 | 349 | |
abc490a1 MD |
350 | t = ht->t; |
351 | /* Check that the table is empty */ | |
352 | node = t->tbl[0]; | |
353 | do { | |
354 | if (!node->dummy) | |
355 | return -EPERM; | |
356 | node = node->next; | |
357 | } while (node); | |
358 | /* Internal sanity check: all nodes left should be dummy */ | |
395270b6 | 359 | for (i = 0; i < t->size; i++) { |
abc490a1 MD |
360 | assert(t->tbl[i]->dummy); |
361 | free(t->tbl[i]); | |
674f7a69 | 362 | } |
abc490a1 | 363 | return 0; |
674f7a69 MD |
364 | } |
365 | ||
366 | /* | |
367 | * Should only be called when no more concurrent readers nor writers can | |
368 | * possibly access the table. | |
369 | */ | |
5e28c532 | 370 | int ht_destroy(struct rcu_ht *ht) |
674f7a69 | 371 | { |
5e28c532 MD |
372 | int ret; |
373 | ||
abc490a1 MD |
374 | ret = ht_delete_dummy(ht); |
375 | if (ret) | |
376 | return ret; | |
395270b6 | 377 | free(ht->t); |
674f7a69 | 378 | free(ht); |
5e28c532 | 379 | return ret; |
674f7a69 MD |
380 | } |
381 | ||
abc490a1 MD |
382 | static |
383 | void ht_free_table_cb(struct rcu_head *head) | |
384 | { | |
385 | struct rcu_table *t = | |
386 | caa_container_of(head, struct rcu_table, head); | |
387 | free(t); | |
388 | } | |
389 | ||
390 | /* called with resize mutex held */ | |
391 | static | |
392 | void _do_ht_resize(struct rcu_ht *ht) | |
464a1ec9 | 393 | { |
abc490a1 | 394 | unsigned long new_size, old_size; |
395270b6 | 395 | struct rcu_table *new_t, *old_t; |
464a1ec9 | 396 | |
395270b6 MD |
397 | old_t = ht->t; |
398 | old_size = old_t->size; | |
464a1ec9 | 399 | |
abc490a1 MD |
400 | new_size = CMM_LOAD_SHARED(ht->target_size); |
401 | if (old_size == new_size) | |
464a1ec9 | 402 | return; |
abc490a1 MD |
403 | new_t = realloc(old_t, sizeof(struct rcu_table) |
404 | + (new_size * sizeof(struct rcu_ht_node *))); | |
405 | if (new_size > old_size) | |
406 | init_table(ht, new_t, old_size, new_size - old_size); | |
407 | cmm_smp_wmb(); /* update content before updating reallocated size */ | |
408 | CMM_STORE_SHARED(new_t->size, new_size); | |
409 | if (new_t != old_t) { | |
410 | /* Changing table and size atomically wrt lookups */ | |
411 | rcu_assign_pointer(ht->t, new_t); | |
412 | ht->ht_call_rcu(&old_t->head, ht_free_table_cb); | |
464a1ec9 | 413 | } |
464a1ec9 MD |
414 | } |
415 | ||
abc490a1 MD |
416 | static |
417 | void resize_target_update(struct rcu_ht *ht, int growth_order) | |
464a1ec9 | 418 | { |
abc490a1 MD |
419 | _uatomic_max(&ht->target_size, |
420 | CMM_LOAD_SHARED(ht->target_size) << growth_order); | |
464a1ec9 MD |
421 | } |
422 | ||
464a1ec9 MD |
423 | void ht_resize(struct rcu_ht *ht, int growth) |
424 | { | |
abc490a1 MD |
425 | resize_target_update(ht, growth); |
426 | pthread_mutex_lock(&ht->resize_mutex); | |
427 | _do_ht_resize(ht); | |
428 | pthread_mutex_unlock(&ht->resize_mutex); | |
429 | } | |
464a1ec9 | 430 | |
abc490a1 MD |
431 | static |
432 | void do_resize_cb(struct rcu_head *head) | |
433 | { | |
434 | struct rcu_resize_work *work = | |
435 | caa_container_of(head, struct rcu_resize_work, head); | |
436 | struct rcu_ht *ht = work->ht; | |
437 | ||
438 | pthread_mutex_lock(&ht->resize_mutex); | |
439 | _do_ht_resize(ht); | |
440 | pthread_mutex_unlock(&ht->resize_mutex); | |
441 | free(work); | |
464a1ec9 MD |
442 | } |
443 | ||
abc490a1 MD |
444 | static |
445 | void ht_resize_lazy(struct rcu_ht *ht, int growth) | |
ab7d5fc6 | 446 | { |
abc490a1 MD |
447 | struct rcu_resize_work *work; |
448 | ||
449 | work = malloc(sizeof(*work)); | |
450 | work->ht = ht; | |
451 | resize_target_update(ht, growth); | |
452 | ht->ht_call_rcu(&work->head, do_resize_cb); | |
ab7d5fc6 | 453 | } |