| 1 | /* |
| 2 | * rcuja/rcuja-hashtable.c |
| 3 | * |
| 4 | * Userspace RCU library - RCU Judy Array Shadow Node Hash Table |
| 5 | * |
| 6 | * Copyright 2012 - 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 |
| 21 | */ |
| 22 | |
| 23 | #define _LGPL_SOURCE |
| 24 | #include <stdint.h> |
| 25 | #include <errno.h> |
| 26 | #include <limits.h> |
| 27 | #include <urcu/rcuja.h> |
| 28 | #include <urcu/compiler.h> |
| 29 | #include <urcu/arch.h> |
| 30 | #include <assert.h> |
| 31 | #include <urcu-pointer.h> |
| 32 | #include <stdlib.h> |
| 33 | #include <time.h> |
| 34 | |
| 35 | #include "rcuja-internal.h" |
| 36 | #include "bitfield.h" |
| 37 | |
| 38 | static unsigned long hash_seed; |
| 39 | |
| 40 | /* |
| 41 | * Hash function |
| 42 | * Source: http://burtleburtle.net/bob/c/lookup3.c |
| 43 | * Originally Public Domain |
| 44 | */ |
| 45 | |
| 46 | #define rot(x, k) (((x) << (k)) | ((x) >> (32 - (k)))) |
| 47 | |
| 48 | #define mix(a, b, c) \ |
| 49 | do { \ |
| 50 | a -= c; a ^= rot(c, 4); c += b; \ |
| 51 | b -= a; b ^= rot(a, 6); a += c; \ |
| 52 | c -= b; c ^= rot(b, 8); b += a; \ |
| 53 | a -= c; a ^= rot(c, 16); c += b; \ |
| 54 | b -= a; b ^= rot(a, 19); a += c; \ |
| 55 | c -= b; c ^= rot(b, 4); b += a; \ |
| 56 | } while (0) |
| 57 | |
| 58 | #define final(a, b, c) \ |
| 59 | { \ |
| 60 | c ^= b; c -= rot(b, 14); \ |
| 61 | a ^= c; a -= rot(c, 11); \ |
| 62 | b ^= a; b -= rot(a, 25); \ |
| 63 | c ^= b; c -= rot(b, 16); \ |
| 64 | a ^= c; a -= rot(c, 4);\ |
| 65 | b ^= a; b -= rot(a, 14); \ |
| 66 | c ^= b; c -= rot(b, 24); \ |
| 67 | } |
| 68 | |
| 69 | static inline __attribute__((unused)) |
| 70 | uint32_t hash_u32( |
| 71 | const uint32_t *k, /* the key, an array of uint32_t values */ |
| 72 | size_t length, /* the length of the key, in uint32_ts */ |
| 73 | uint32_t initval) /* the previous hash, or an arbitrary value */ |
| 74 | { |
| 75 | uint32_t a, b, c; |
| 76 | |
| 77 | /* Set up the internal state */ |
| 78 | a = b = c = 0xdeadbeef + (((uint32_t) length) << 2) + initval; |
| 79 | |
| 80 | /*----------------------------------------- handle most of the key */ |
| 81 | while (length > 3) { |
| 82 | a += k[0]; |
| 83 | b += k[1]; |
| 84 | c += k[2]; |
| 85 | mix(a, b, c); |
| 86 | length -= 3; |
| 87 | k += 3; |
| 88 | } |
| 89 | |
| 90 | /*----------------------------------- handle the last 3 uint32_t's */ |
| 91 | switch (length) { /* all the case statements fall through */ |
| 92 | case 3: c += k[2]; |
| 93 | case 2: b += k[1]; |
| 94 | case 1: a += k[0]; |
| 95 | final(a, b, c); |
| 96 | case 0: /* case 0: nothing left to add */ |
| 97 | break; |
| 98 | } |
| 99 | /*---------------------------------------------- report the result */ |
| 100 | return c; |
| 101 | } |
| 102 | |
| 103 | static inline |
| 104 | void hashword2( |
| 105 | const uint32_t *k, /* the key, an array of uint32_t values */ |
| 106 | size_t length, /* the length of the key, in uint32_ts */ |
| 107 | uint32_t *pc, /* IN: seed OUT: primary hash value */ |
| 108 | uint32_t *pb) /* IN: more seed OUT: secondary hash value */ |
| 109 | { |
| 110 | uint32_t a, b, c; |
| 111 | |
| 112 | /* Set up the internal state */ |
| 113 | a = b = c = 0xdeadbeef + ((uint32_t) (length << 2)) + *pc; |
| 114 | c += *pb; |
| 115 | |
| 116 | /*----------------------------------------- handle most of the key */ |
| 117 | while (length > 3) { |
| 118 | a += k[0]; |
| 119 | b += k[1]; |
| 120 | c += k[2]; |
| 121 | mix(a, b, c); |
| 122 | length -= 3; |
| 123 | k += 3; |
| 124 | } |
| 125 | |
| 126 | /*----------------------------------- handle the last 3 uint32_t's */ |
| 127 | switch (length) { /* all the case statements fall through */ |
| 128 | case 3: c += k[2]; |
| 129 | case 2: b += k[1]; |
| 130 | case 1: a += k[0]; |
| 131 | final(a, b, c); |
| 132 | case 0: /* case 0: nothing left to add */ |
| 133 | break; |
| 134 | } |
| 135 | /*---------------------------------------------- report the result */ |
| 136 | *pc = c; |
| 137 | *pb = b; |
| 138 | } |
| 139 | |
| 140 | #if (CAA_BITS_PER_LONG == 32) |
| 141 | static |
| 142 | unsigned long hash_pointer(const void *_key, unsigned long seed) |
| 143 | { |
| 144 | unsigned int key = (unsigned int) _key; |
| 145 | |
| 146 | return hash_u32(&key, 1, seed); |
| 147 | } |
| 148 | #else |
| 149 | static |
| 150 | unsigned long hash_pointer(const void *_key, unsigned long seed) |
| 151 | { |
| 152 | union { |
| 153 | uint64_t v64; |
| 154 | uint32_t v32[2]; |
| 155 | } v; |
| 156 | union { |
| 157 | uint64_t v64; |
| 158 | uint32_t v32[2]; |
| 159 | } key; |
| 160 | |
| 161 | v.v64 = (uint64_t) seed; |
| 162 | key.v64 = (uint64_t) _key; |
| 163 | hashword2(key.v32, 2, &v.v32[0], &v.v32[1]); |
| 164 | return v.v64; |
| 165 | } |
| 166 | #endif |
| 167 | |
| 168 | static |
| 169 | int match_pointer(struct cds_lfht_node *node, const void *key) |
| 170 | { |
| 171 | struct cds_ja_shadow_node *shadow = |
| 172 | caa_container_of(node, struct cds_ja_shadow_node, ht_node); |
| 173 | |
| 174 | return (key == shadow->node); |
| 175 | } |
| 176 | |
| 177 | __attribute__((visibility("protected"))) |
| 178 | struct cds_ja_shadow_node *rcuja_shadow_lookup_lock(struct cds_lfht *ht, |
| 179 | struct cds_ja_inode *node) |
| 180 | { |
| 181 | struct cds_lfht_iter iter; |
| 182 | struct cds_lfht_node *lookup_node; |
| 183 | struct cds_ja_shadow_node *shadow_node; |
| 184 | const struct rcu_flavor_struct *flavor; |
| 185 | int ret; |
| 186 | |
| 187 | flavor = cds_lfht_rcu_flavor(ht); |
| 188 | flavor->read_lock(); |
| 189 | cds_lfht_lookup(ht, hash_pointer(node, hash_seed), |
| 190 | match_pointer, node, &iter); |
| 191 | |
| 192 | lookup_node = cds_lfht_iter_get_node(&iter); |
| 193 | if (!lookup_node) { |
| 194 | shadow_node = NULL; |
| 195 | goto rcu_unlock; |
| 196 | } |
| 197 | shadow_node = caa_container_of(lookup_node, |
| 198 | struct cds_ja_shadow_node, ht_node); |
| 199 | dbg_printf("Lock %p\n", shadow_node->lock); |
| 200 | ret = pthread_mutex_lock(shadow_node->lock); |
| 201 | assert(!ret); |
| 202 | if (cds_lfht_is_node_deleted(lookup_node)) { |
| 203 | ret = pthread_mutex_unlock(shadow_node->lock); |
| 204 | assert(!ret); |
| 205 | shadow_node = NULL; |
| 206 | } |
| 207 | rcu_unlock: |
| 208 | flavor->read_unlock(); |
| 209 | return shadow_node; |
| 210 | } |
| 211 | |
| 212 | __attribute__((visibility("protected"))) |
| 213 | void rcuja_shadow_unlock(struct cds_ja_shadow_node *shadow_node) |
| 214 | { |
| 215 | int ret; |
| 216 | |
| 217 | dbg_printf("Unlock %p\n", shadow_node->lock); |
| 218 | ret = pthread_mutex_unlock(shadow_node->lock); |
| 219 | assert(!ret); |
| 220 | } |
| 221 | |
| 222 | __attribute__((visibility("protected"))) |
| 223 | struct cds_ja_shadow_node *rcuja_shadow_set(struct cds_lfht *ht, |
| 224 | struct cds_ja_inode *new_node, |
| 225 | struct cds_ja_shadow_node *inherit_from) |
| 226 | { |
| 227 | struct cds_ja_shadow_node *shadow_node; |
| 228 | struct cds_lfht_node *ret_node; |
| 229 | const struct rcu_flavor_struct *flavor; |
| 230 | |
| 231 | shadow_node = calloc(sizeof(*shadow_node), 1); |
| 232 | if (!shadow_node) |
| 233 | return NULL; |
| 234 | |
| 235 | shadow_node->node = new_node; |
| 236 | /* |
| 237 | * Lock can be inherited from previous node at this position. |
| 238 | */ |
| 239 | if (inherit_from) { |
| 240 | shadow_node->lock = inherit_from->lock; |
| 241 | } else { |
| 242 | shadow_node->lock = calloc(sizeof(*shadow_node->lock), 1); |
| 243 | if (!shadow_node->lock) { |
| 244 | free(shadow_node); |
| 245 | return NULL; |
| 246 | } |
| 247 | pthread_mutex_init(shadow_node->lock, NULL); |
| 248 | } |
| 249 | |
| 250 | flavor = cds_lfht_rcu_flavor(ht); |
| 251 | flavor->read_lock(); |
| 252 | ret_node = cds_lfht_add_unique(ht, |
| 253 | hash_pointer(new_node, hash_seed), |
| 254 | match_pointer, |
| 255 | new_node, |
| 256 | &shadow_node->ht_node); |
| 257 | flavor->read_unlock(); |
| 258 | |
| 259 | if (ret_node != &shadow_node->ht_node) { |
| 260 | free(shadow_node); |
| 261 | return NULL; |
| 262 | } |
| 263 | return shadow_node; |
| 264 | } |
| 265 | |
| 266 | static |
| 267 | void free_shadow_node(struct rcu_head *head) |
| 268 | { |
| 269 | struct cds_ja_shadow_node *shadow_node = |
| 270 | caa_container_of(head, struct cds_ja_shadow_node, head); |
| 271 | free(shadow_node); |
| 272 | } |
| 273 | |
| 274 | static |
| 275 | void free_shadow_node_and_node(struct rcu_head *head) |
| 276 | { |
| 277 | struct cds_ja_shadow_node *shadow_node = |
| 278 | caa_container_of(head, struct cds_ja_shadow_node, head); |
| 279 | free(shadow_node->node); |
| 280 | free(shadow_node); |
| 281 | } |
| 282 | |
| 283 | static |
| 284 | void free_shadow_node_and_lock(struct rcu_head *head) |
| 285 | { |
| 286 | struct cds_ja_shadow_node *shadow_node = |
| 287 | caa_container_of(head, struct cds_ja_shadow_node, head); |
| 288 | free(shadow_node->lock); |
| 289 | free(shadow_node); |
| 290 | } |
| 291 | |
| 292 | static |
| 293 | void free_shadow_node_and_node_and_lock(struct rcu_head *head) |
| 294 | { |
| 295 | struct cds_ja_shadow_node *shadow_node = |
| 296 | caa_container_of(head, struct cds_ja_shadow_node, head); |
| 297 | assert(!shadow_node->is_root); |
| 298 | free(shadow_node->node); |
| 299 | free(shadow_node->lock); |
| 300 | free(shadow_node); |
| 301 | } |
| 302 | |
| 303 | __attribute__((visibility("protected"))) |
| 304 | int rcuja_shadow_clear(struct cds_lfht *ht, |
| 305 | struct cds_ja_inode *node, |
| 306 | struct cds_ja_shadow_node *shadow_node, |
| 307 | unsigned int flags) |
| 308 | { |
| 309 | struct cds_lfht_iter iter; |
| 310 | struct cds_lfht_node *lookup_node; |
| 311 | const struct rcu_flavor_struct *flavor; |
| 312 | int ret, lockret; |
| 313 | int lookup_shadow = 0; |
| 314 | |
| 315 | flavor = cds_lfht_rcu_flavor(ht); |
| 316 | flavor->read_lock(); |
| 317 | |
| 318 | cds_lfht_lookup(ht, hash_pointer(node, hash_seed), |
| 319 | match_pointer, node, &iter); |
| 320 | lookup_node = cds_lfht_iter_get_node(&iter); |
| 321 | if (!lookup_node) { |
| 322 | ret = -ENOENT; |
| 323 | goto rcu_unlock; |
| 324 | } |
| 325 | |
| 326 | if (!shadow_node) { |
| 327 | shadow_node = caa_container_of(lookup_node, |
| 328 | struct cds_ja_shadow_node, ht_node); |
| 329 | lockret = pthread_mutex_lock(shadow_node->lock); |
| 330 | assert(!lockret); |
| 331 | lookup_shadow = 1; |
| 332 | } |
| 333 | |
| 334 | /* |
| 335 | * Holding the mutex across deletion, and by also re-checking if |
| 336 | * the node is deleted with mutex held at lookup ensure that we |
| 337 | * don't let RCU JA use a node being removed. |
| 338 | */ |
| 339 | ret = cds_lfht_del(ht, lookup_node); |
| 340 | if (!ret) { |
| 341 | if ((flags & RCUJA_SHADOW_CLEAR_FREE_NODE) |
| 342 | && !shadow_node->is_root) { |
| 343 | if (flags & RCUJA_SHADOW_CLEAR_FREE_LOCK) { |
| 344 | flavor->update_call_rcu(&shadow_node->head, |
| 345 | free_shadow_node_and_node_and_lock); |
| 346 | } else { |
| 347 | flavor->update_call_rcu(&shadow_node->head, |
| 348 | free_shadow_node_and_node); |
| 349 | } |
| 350 | } else { |
| 351 | if (flags & RCUJA_SHADOW_CLEAR_FREE_LOCK) { |
| 352 | flavor->update_call_rcu(&shadow_node->head, |
| 353 | free_shadow_node_and_lock); |
| 354 | } else { |
| 355 | flavor->update_call_rcu(&shadow_node->head, |
| 356 | free_shadow_node); |
| 357 | } |
| 358 | } |
| 359 | } |
| 360 | if (lookup_shadow) { |
| 361 | lockret = pthread_mutex_unlock(shadow_node->lock); |
| 362 | assert(!lockret); |
| 363 | } |
| 364 | rcu_unlock: |
| 365 | flavor->read_unlock(); |
| 366 | |
| 367 | return ret; |
| 368 | } |
| 369 | |
| 370 | /* |
| 371 | * Delete all shadow nodes and nodes from hash table, along with their |
| 372 | * associated lock. |
| 373 | */ |
| 374 | __attribute__((visibility("protected"))) |
| 375 | void rcuja_shadow_prune(struct cds_lfht *ht, |
| 376 | unsigned int flags) |
| 377 | { |
| 378 | const struct rcu_flavor_struct *flavor; |
| 379 | struct cds_ja_shadow_node *shadow_node; |
| 380 | struct cds_lfht_iter iter; |
| 381 | int ret, lockret; |
| 382 | |
| 383 | flavor = cds_lfht_rcu_flavor(ht); |
| 384 | flavor->read_lock(); |
| 385 | cds_lfht_for_each_entry(ht, &iter, shadow_node, ht_node) { |
| 386 | lockret = pthread_mutex_lock(shadow_node->lock); |
| 387 | assert(!lockret); |
| 388 | |
| 389 | ret = cds_lfht_del(ht, &shadow_node->ht_node); |
| 390 | if (!ret) { |
| 391 | if ((flags & RCUJA_SHADOW_CLEAR_FREE_NODE) |
| 392 | && !shadow_node->is_root) { |
| 393 | if (flags & RCUJA_SHADOW_CLEAR_FREE_LOCK) { |
| 394 | flavor->update_call_rcu(&shadow_node->head, |
| 395 | free_shadow_node_and_node_and_lock); |
| 396 | } else { |
| 397 | flavor->update_call_rcu(&shadow_node->head, |
| 398 | free_shadow_node_and_node); |
| 399 | } |
| 400 | } else { |
| 401 | if (flags & RCUJA_SHADOW_CLEAR_FREE_LOCK) { |
| 402 | flavor->update_call_rcu(&shadow_node->head, |
| 403 | free_shadow_node_and_lock); |
| 404 | } else { |
| 405 | flavor->update_call_rcu(&shadow_node->head, |
| 406 | free_shadow_node); |
| 407 | } |
| 408 | } |
| 409 | } |
| 410 | lockret = pthread_mutex_unlock(shadow_node->lock); |
| 411 | assert(!lockret); |
| 412 | } |
| 413 | flavor->read_unlock(); |
| 414 | } |
| 415 | |
| 416 | __attribute__((visibility("protected"))) |
| 417 | struct cds_lfht *rcuja_create_ht(const struct rcu_flavor_struct *flavor) |
| 418 | { |
| 419 | return _cds_lfht_new(1, 1, 0, |
| 420 | CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, |
| 421 | NULL, flavor, NULL); |
| 422 | } |
| 423 | |
| 424 | __attribute__((visibility("protected"))) |
| 425 | int rcuja_delete_ht(struct cds_lfht *ht) |
| 426 | { |
| 427 | return cds_lfht_destroy(ht, NULL); |
| 428 | } |
| 429 | |
| 430 | __attribute__((constructor)) |
| 431 | void rcuja_ht_init(void) |
| 432 | { |
| 433 | hash_seed = (unsigned long) time(NULL); |
| 434 | } |