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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 | ||
e753ff5a MD |
23 | /* |
24 | * Based on the following articles: | |
25 | * - Ori Shalev and Nir Shavit. Split-ordered lists: Lock-free | |
26 | * extensible hash tables. J. ACM 53, 3 (May 2006), 379-405. | |
27 | * - Michael, M. M. High performance dynamic lock-free hash tables | |
28 | * and list-based sets. In Proceedings of the fourteenth annual ACM | |
29 | * symposium on Parallel algorithms and architectures, ACM Press, | |
30 | * (2002), 73-82. | |
31 | * | |
32 | * Some specificities of this Lock-Free Expandable RCU Hash Table | |
33 | * implementation: | |
34 | * | |
35 | * - RCU read-side critical section allows readers to perform hash | |
36 | * table lookups and use the returned objects safely by delaying | |
37 | * memory reclaim of a grace period. | |
38 | * - Add and remove operations are lock-free, and do not need to | |
39 | * allocate memory. They need to be executed within RCU read-side | |
40 | * critical section to ensure the objects they read are valid and to | |
41 | * deal with the cmpxchg ABA problem. | |
42 | * - add and add_unique operations are supported. add_unique checks if | |
43 | * the node key already exists in the hash table. It ensures no key | |
44 | * duplicata exists. | |
45 | * - The resize operation executes concurrently with add/remove/lookup. | |
46 | * - Hash table nodes are contained within a split-ordered list. This | |
47 | * list is ordered by incrementing reversed-bits-hash value. | |
48 | * - An index of dummy nodes is kept. These dummy nodes are the hash | |
49 | * table "buckets", and they are also chained together in the | |
50 | * split-ordered list, which allows recursive expansion. | |
51 | * - The resize operation only allows expanding the hash table. | |
52 | * It is triggered either through an API call or automatically by | |
53 | * detecting long chains in the add operation. | |
54 | * - Resize operation initiated by long chain detection is executed by a | |
55 | * call_rcu thread, which keeps lock-freedom of add and remove. | |
56 | * - Resize operations are protected by a mutex. | |
57 | * - The removal operation is split in two parts: first, a "removed" | |
58 | * flag is set in the next pointer within the node to remove. Then, | |
59 | * a "garbage collection" is performed in the bucket containing the | |
60 | * removed node (from the start of the bucket up to the removed node). | |
61 | * All encountered nodes with "removed" flag set in their next | |
62 | * pointers are removed from the linked-list. If the cmpxchg used for | |
63 | * removal fails (due to concurrent garbage-collection or concurrent | |
64 | * add), we retry from the beginning of the bucket. This ensures that | |
65 | * the node with "removed" flag set is removed from the hash table | |
66 | * (not visible to lookups anymore) before the RCU read-side critical | |
67 | * section held across removal ends. Furthermore, this ensures that | |
68 | * the node with "removed" flag set is removed from the linked-list | |
69 | * before its memory is reclaimed. Only the thread which removal | |
70 | * successfully set the "removed" flag (with a cmpxchg) into a node's | |
71 | * next pointer is considered to have succeeded its removal (and thus | |
72 | * owns the node to reclaim). Because we garbage-collect starting from | |
73 | * an invariant node (the start-of-bucket dummy node) up to the | |
74 | * "removed" node (or find a reverse-hash that is higher), we are sure | |
75 | * that a successful traversal of the chain leads to a chain that is | |
76 | * present in the linked-list (the start node is never removed) and | |
77 | * that is does not contain the "removed" node anymore, even if | |
78 | * concurrent delete/add operations are changing the structure of the | |
79 | * list concurrently. | |
29e669f6 MD |
80 | * - The add operation performs gargage collection of buckets if it |
81 | * encounters nodes with removed flag set in the bucket where it wants | |
82 | * to add its new node. This ensures lock-freedom of add operation by | |
83 | * helping the remover unlink nodes from the list rather than to wait | |
84 | * for it do to so. | |
e753ff5a MD |
85 | * - A RCU "order table" indexed by log2(hash index) is copied and |
86 | * expanded by the resize operation. This order table allows finding | |
87 | * the "dummy node" tables. | |
88 | * - There is one dummy node table per hash index order. The size of | |
89 | * each dummy node table is half the number of hashes contained in | |
90 | * this order. | |
91 | * - call_rcu is used to garbage-collect the old order table. | |
92 | * - The per-order dummy node tables contain a compact version of the | |
93 | * hash table nodes. These tables are invariant after they are | |
94 | * populated into the hash table. | |
95 | */ | |
96 | ||
2ed95849 MD |
97 | #define _LGPL_SOURCE |
98 | #include <stdlib.h> | |
e0ba718a MD |
99 | #include <errno.h> |
100 | #include <assert.h> | |
101 | #include <stdio.h> | |
abc490a1 | 102 | #include <stdint.h> |
f000907d | 103 | #include <string.h> |
e0ba718a | 104 | |
2ed95849 | 105 | #include <urcu.h> |
abc490a1 | 106 | #include <urcu-call-rcu.h> |
a42cc659 MD |
107 | #include <urcu/arch.h> |
108 | #include <urcu/uatomic.h> | |
674f7a69 | 109 | #include <urcu/jhash.h> |
a42cc659 | 110 | #include <urcu/compiler.h> |
abc490a1 | 111 | #include <urcu/rculfhash.h> |
5e28c532 | 112 | #include <stdio.h> |
464a1ec9 | 113 | #include <pthread.h> |
44395fb7 | 114 | |
f9830efd | 115 | #ifdef DEBUG |
f0c29ed7 | 116 | #define dbg_printf(fmt, args...) printf("[debug rculfhash] " fmt, ## args) |
f9830efd | 117 | #else |
e753ff5a | 118 | #define dbg_printf(fmt, args...) |
f9830efd MD |
119 | #endif |
120 | ||
01370f0b MD |
121 | #define CHAIN_LEN_TARGET 4 |
122 | #define CHAIN_LEN_RESIZE_THRESHOLD 8 | |
2ed95849 | 123 | |
abc490a1 MD |
124 | #ifndef max |
125 | #define max(a, b) ((a) > (b) ? (a) : (b)) | |
126 | #endif | |
2ed95849 | 127 | |
d95bd160 MD |
128 | /* |
129 | * The removed flag needs to be updated atomically with the pointer. | |
130 | * The dummy flag does not require to be updated atomically with the | |
131 | * pointer, but it is added as a pointer low bit flag to save space. | |
132 | */ | |
d37166c6 | 133 | #define REMOVED_FLAG (1UL << 0) |
f5596c94 MD |
134 | #define DUMMY_FLAG (1UL << 1) |
135 | #define FLAGS_MASK ((1UL << 2) - 1) | |
d37166c6 | 136 | |
395270b6 | 137 | struct rcu_table { |
abc490a1 | 138 | unsigned long size; /* always a power of 2 */ |
f9830efd | 139 | unsigned long resize_target; |
11519af6 | 140 | int resize_initiated; |
abc490a1 | 141 | struct rcu_head head; |
24365af7 | 142 | struct _rcu_ht_node *tbl[0]; |
395270b6 MD |
143 | }; |
144 | ||
2ed95849 | 145 | struct rcu_ht { |
395270b6 | 146 | struct rcu_table *t; /* shared */ |
2ed95849 | 147 | ht_hash_fct hash_fct; |
732ad076 MD |
148 | ht_compare_fct compare_fct; |
149 | unsigned long hash_seed; | |
464a1ec9 | 150 | pthread_mutex_t resize_mutex; /* resize mutex: add/del mutex */ |
33c7c748 | 151 | unsigned int in_progress_resize, in_progress_destroy; |
abc490a1 MD |
152 | void (*ht_call_rcu)(struct rcu_head *head, |
153 | void (*func)(struct rcu_head *head)); | |
2ed95849 MD |
154 | }; |
155 | ||
abc490a1 MD |
156 | struct rcu_resize_work { |
157 | struct rcu_head head; | |
2ed95849 | 158 | struct rcu_ht *ht; |
abc490a1 | 159 | }; |
2ed95849 | 160 | |
abc490a1 MD |
161 | /* |
162 | * Algorithm to reverse bits in a word by lookup table, extended to | |
163 | * 64-bit words. | |
f9830efd | 164 | * Source: |
abc490a1 | 165 | * http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable |
f9830efd | 166 | * Originally from Public Domain. |
abc490a1 MD |
167 | */ |
168 | ||
169 | static const uint8_t BitReverseTable256[256] = | |
2ed95849 | 170 | { |
abc490a1 MD |
171 | #define R2(n) (n), (n) + 2*64, (n) + 1*64, (n) + 3*64 |
172 | #define R4(n) R2(n), R2((n) + 2*16), R2((n) + 1*16), R2((n) + 3*16) | |
173 | #define R6(n) R4(n), R4((n) + 2*4 ), R4((n) + 1*4 ), R4((n) + 3*4 ) | |
174 | R6(0), R6(2), R6(1), R6(3) | |
175 | }; | |
176 | #undef R2 | |
177 | #undef R4 | |
178 | #undef R6 | |
2ed95849 | 179 | |
abc490a1 MD |
180 | static |
181 | uint8_t bit_reverse_u8(uint8_t v) | |
182 | { | |
183 | return BitReverseTable256[v]; | |
184 | } | |
ab7d5fc6 | 185 | |
abc490a1 MD |
186 | static __attribute__((unused)) |
187 | uint32_t bit_reverse_u32(uint32_t v) | |
188 | { | |
189 | return ((uint32_t) bit_reverse_u8(v) << 24) | | |
190 | ((uint32_t) bit_reverse_u8(v >> 8) << 16) | | |
191 | ((uint32_t) bit_reverse_u8(v >> 16) << 8) | | |
192 | ((uint32_t) bit_reverse_u8(v >> 24)); | |
2ed95849 MD |
193 | } |
194 | ||
abc490a1 MD |
195 | static __attribute__((unused)) |
196 | uint64_t bit_reverse_u64(uint64_t v) | |
2ed95849 | 197 | { |
abc490a1 MD |
198 | return ((uint64_t) bit_reverse_u8(v) << 56) | |
199 | ((uint64_t) bit_reverse_u8(v >> 8) << 48) | | |
200 | ((uint64_t) bit_reverse_u8(v >> 16) << 40) | | |
201 | ((uint64_t) bit_reverse_u8(v >> 24) << 32) | | |
202 | ((uint64_t) bit_reverse_u8(v >> 32) << 24) | | |
203 | ((uint64_t) bit_reverse_u8(v >> 40) << 16) | | |
204 | ((uint64_t) bit_reverse_u8(v >> 48) << 8) | | |
205 | ((uint64_t) bit_reverse_u8(v >> 56)); | |
206 | } | |
207 | ||
208 | static | |
209 | unsigned long bit_reverse_ulong(unsigned long v) | |
210 | { | |
211 | #if (CAA_BITS_PER_LONG == 32) | |
212 | return bit_reverse_u32(v); | |
213 | #else | |
214 | return bit_reverse_u64(v); | |
215 | #endif | |
216 | } | |
217 | ||
f9830efd | 218 | /* |
24365af7 MD |
219 | * fls: returns the position of the most significant bit. |
220 | * Returns 0 if no bit is set, else returns the position of the most | |
221 | * significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit). | |
f9830efd | 222 | */ |
24365af7 MD |
223 | #if defined(__i386) || defined(__x86_64) |
224 | static inline | |
225 | unsigned int fls_u32(uint32_t x) | |
f9830efd | 226 | { |
24365af7 MD |
227 | int r; |
228 | ||
229 | asm("bsrl %1,%0\n\t" | |
230 | "jnz 1f\n\t" | |
231 | "movl $-1,%0\n\t" | |
232 | "1:\n\t" | |
233 | : "=r" (r) : "rm" (x)); | |
234 | return r + 1; | |
235 | } | |
236 | #define HAS_FLS_U32 | |
237 | #endif | |
238 | ||
239 | #if defined(__x86_64) | |
240 | static inline | |
241 | unsigned int fls_u64(uint64_t x) | |
242 | { | |
243 | long r; | |
244 | ||
245 | asm("bsrq %1,%0\n\t" | |
246 | "jnz 1f\n\t" | |
247 | "movq $-1,%0\n\t" | |
248 | "1:\n\t" | |
249 | : "=r" (r) : "rm" (x)); | |
250 | return r + 1; | |
251 | } | |
252 | #define HAS_FLS_U64 | |
253 | #endif | |
254 | ||
255 | #ifndef HAS_FLS_U64 | |
256 | static __attribute__((unused)) | |
257 | unsigned int fls_u64(uint64_t x) | |
258 | { | |
259 | unsigned int r = 64; | |
260 | ||
261 | if (!x) | |
262 | return 0; | |
263 | ||
264 | if (!(x & 0xFFFFFFFF00000000ULL)) { | |
265 | x <<= 32; | |
266 | r -= 32; | |
267 | } | |
268 | if (!(x & 0xFFFF000000000000ULL)) { | |
269 | x <<= 16; | |
270 | r -= 16; | |
271 | } | |
272 | if (!(x & 0xFF00000000000000ULL)) { | |
273 | x <<= 8; | |
274 | r -= 8; | |
275 | } | |
276 | if (!(x & 0xF000000000000000ULL)) { | |
277 | x <<= 4; | |
278 | r -= 4; | |
279 | } | |
280 | if (!(x & 0xC000000000000000ULL)) { | |
281 | x <<= 2; | |
282 | r -= 2; | |
283 | } | |
284 | if (!(x & 0x8000000000000000ULL)) { | |
285 | x <<= 1; | |
286 | r -= 1; | |
287 | } | |
288 | return r; | |
289 | } | |
290 | #endif | |
291 | ||
292 | #ifndef HAS_FLS_U32 | |
293 | static __attribute__((unused)) | |
294 | unsigned int fls_u32(uint32_t x) | |
295 | { | |
296 | unsigned int r = 32; | |
f9830efd | 297 | |
24365af7 MD |
298 | if (!x) |
299 | return 0; | |
300 | if (!(x & 0xFFFF0000U)) { | |
301 | x <<= 16; | |
302 | r -= 16; | |
303 | } | |
304 | if (!(x & 0xFF000000U)) { | |
305 | x <<= 8; | |
306 | r -= 8; | |
307 | } | |
308 | if (!(x & 0xF0000000U)) { | |
309 | x <<= 4; | |
310 | r -= 4; | |
311 | } | |
312 | if (!(x & 0xC0000000U)) { | |
313 | x <<= 2; | |
314 | r -= 2; | |
315 | } | |
316 | if (!(x & 0x80000000U)) { | |
317 | x <<= 1; | |
318 | r -= 1; | |
319 | } | |
320 | return r; | |
321 | } | |
322 | #endif | |
323 | ||
324 | unsigned int fls_ulong(unsigned long x) | |
f9830efd | 325 | { |
24365af7 MD |
326 | #if (CAA_BITS_PER_lONG == 32) |
327 | return fls_u32(x); | |
328 | #else | |
329 | return fls_u64(x); | |
330 | #endif | |
331 | } | |
f9830efd | 332 | |
24365af7 MD |
333 | int get_count_order_u32(uint32_t x) |
334 | { | |
335 | int order; | |
336 | ||
337 | order = fls_u32(x) - 1; | |
338 | if (x & (x - 1)) | |
339 | order++; | |
340 | return order; | |
341 | } | |
342 | ||
343 | int get_count_order_ulong(unsigned long x) | |
344 | { | |
345 | int order; | |
346 | ||
347 | order = fls_ulong(x) - 1; | |
348 | if (x & (x - 1)) | |
349 | order++; | |
350 | return order; | |
f9830efd MD |
351 | } |
352 | ||
353 | static | |
354 | void ht_resize_lazy(struct rcu_ht *ht, struct rcu_table *t, int growth); | |
355 | ||
356 | static | |
357 | void check_resize(struct rcu_ht *ht, struct rcu_table *t, | |
358 | uint32_t chain_len) | |
359 | { | |
24365af7 | 360 | if (chain_len > 100) |
f0c29ed7 | 361 | dbg_printf("WARNING: large chain length: %u.\n", |
24365af7 | 362 | chain_len); |
3390d470 MD |
363 | if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD) |
364 | ht_resize_lazy(ht, t, | |
01370f0b | 365 | get_count_order_u32(chain_len - (CHAIN_LEN_TARGET - 1))); |
f9830efd MD |
366 | } |
367 | ||
abc490a1 MD |
368 | static |
369 | struct rcu_ht_node *clear_flag(struct rcu_ht_node *node) | |
370 | { | |
d37166c6 | 371 | return (struct rcu_ht_node *) (((unsigned long) node) & ~FLAGS_MASK); |
abc490a1 MD |
372 | } |
373 | ||
374 | static | |
375 | int is_removed(struct rcu_ht_node *node) | |
376 | { | |
d37166c6 | 377 | return ((unsigned long) node) & REMOVED_FLAG; |
abc490a1 MD |
378 | } |
379 | ||
380 | static | |
381 | struct rcu_ht_node *flag_removed(struct rcu_ht_node *node) | |
382 | { | |
d37166c6 | 383 | return (struct rcu_ht_node *) (((unsigned long) node) | REMOVED_FLAG); |
abc490a1 MD |
384 | } |
385 | ||
f5596c94 MD |
386 | static |
387 | int is_dummy(struct rcu_ht_node *node) | |
388 | { | |
389 | return ((unsigned long) node) & DUMMY_FLAG; | |
390 | } | |
391 | ||
392 | static | |
393 | struct rcu_ht_node *flag_dummy(struct rcu_ht_node *node) | |
394 | { | |
395 | return (struct rcu_ht_node *) (((unsigned long) node) | DUMMY_FLAG); | |
396 | } | |
397 | ||
abc490a1 | 398 | static |
f9830efd | 399 | unsigned long _uatomic_max(unsigned long *ptr, unsigned long v) |
abc490a1 MD |
400 | { |
401 | unsigned long old1, old2; | |
402 | ||
403 | old1 = uatomic_read(ptr); | |
404 | do { | |
405 | old2 = old1; | |
406 | if (old2 >= v) | |
f9830efd | 407 | return old2; |
abc490a1 | 408 | } while ((old1 = uatomic_cmpxchg(ptr, old2, v)) != old2); |
f9830efd | 409 | return v; |
abc490a1 MD |
410 | } |
411 | ||
273399de MD |
412 | /* |
413 | * Remove all logically deleted nodes from a bucket up to a certain node key. | |
414 | */ | |
415 | static | |
416 | void _ht_gc_bucket(struct rcu_ht_node *dummy, struct rcu_ht_node *node) | |
417 | { | |
f5596c94 | 418 | struct rcu_ht_node *iter_prev, *iter, *next, *new_next; |
273399de MD |
419 | |
420 | for (;;) { | |
421 | iter_prev = dummy; | |
422 | /* We can always skip the dummy node initially */ | |
cc4fcb10 MD |
423 | iter = rcu_dereference(iter_prev->p.next); |
424 | assert(iter_prev->p.reverse_hash <= node->p.reverse_hash); | |
273399de | 425 | for (;;) { |
a2974903 | 426 | if (unlikely(!clear_flag(iter))) |
479c8a32 | 427 | return; |
76412f24 | 428 | if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash)) |
273399de | 429 | return; |
cc4fcb10 | 430 | next = rcu_dereference(clear_flag(iter)->p.next); |
76412f24 | 431 | if (likely(is_removed(next))) |
273399de | 432 | break; |
b453eae1 | 433 | iter_prev = clear_flag(iter); |
273399de MD |
434 | iter = next; |
435 | } | |
436 | assert(!is_removed(iter)); | |
f5596c94 MD |
437 | if (is_dummy(iter)) |
438 | new_next = flag_dummy(clear_flag(next)); | |
439 | else | |
440 | new_next = clear_flag(next); | |
441 | (void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next); | |
273399de MD |
442 | } |
443 | } | |
444 | ||
abc490a1 | 445 | static |
18117871 | 446 | struct rcu_ht_node *_ht_add(struct rcu_ht *ht, struct rcu_table *t, |
f5596c94 | 447 | struct rcu_ht_node *node, int unique, int dummy) |
abc490a1 | 448 | { |
f5596c94 MD |
449 | struct rcu_ht_node *iter_prev, *iter, *next, *new_node, *new_next, |
450 | *dummy_node; | |
24365af7 MD |
451 | struct _rcu_ht_node *lookup; |
452 | unsigned long hash, index, order; | |
abc490a1 | 453 | |
18117871 | 454 | if (!t->size) { |
f5596c94 MD |
455 | assert(dummy); |
456 | node->p.next = flag_dummy(NULL); | |
18117871 MD |
457 | return node; /* Initial first add (head) */ |
458 | } | |
cc4fcb10 | 459 | hash = bit_reverse_ulong(node->p.reverse_hash); |
abc490a1 | 460 | for (;;) { |
f9830efd | 461 | uint32_t chain_len = 0; |
abc490a1 | 462 | |
11519af6 MD |
463 | /* |
464 | * iter_prev points to the non-removed node prior to the | |
465 | * insert location. | |
11519af6 | 466 | */ |
24365af7 MD |
467 | index = hash & (t->size - 1); |
468 | order = get_count_order_ulong(index + 1); | |
469 | lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)]; | |
470 | iter_prev = (struct rcu_ht_node *) lookup; | |
11519af6 | 471 | /* We can always skip the dummy node initially */ |
cc4fcb10 MD |
472 | iter = rcu_dereference(iter_prev->p.next); |
473 | assert(iter_prev->p.reverse_hash <= node->p.reverse_hash); | |
abc490a1 | 474 | for (;;) { |
a2974903 | 475 | if (unlikely(!clear_flag(iter))) |
273399de | 476 | goto insert; |
76412f24 | 477 | if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash)) |
273399de | 478 | goto insert; |
cc4fcb10 | 479 | next = rcu_dereference(clear_flag(iter)->p.next); |
76412f24 | 480 | if (unlikely(is_removed(next))) |
9dba85be | 481 | goto gc_node; |
e43f23f8 | 482 | if (unique |
1b81fe1a | 483 | && !is_dummy(next) |
e43f23f8 MD |
484 | && !ht->compare_fct(node->key, node->key_len, |
485 | clear_flag(iter)->key, | |
486 | clear_flag(iter)->key_len)) | |
18117871 | 487 | return clear_flag(iter); |
11519af6 | 488 | /* Only account for identical reverse hash once */ |
24365af7 MD |
489 | if (iter_prev->p.reverse_hash != clear_flag(iter)->p.reverse_hash |
490 | && !is_dummy(next)) | |
11519af6 MD |
491 | check_resize(ht, t, ++chain_len); |
492 | iter_prev = clear_flag(iter); | |
273399de | 493 | iter = next; |
abc490a1 | 494 | } |
273399de | 495 | insert: |
7ec59d3b | 496 | assert(node != clear_flag(iter)); |
11519af6 | 497 | assert(!is_removed(iter_prev)); |
f000907d | 498 | assert(iter_prev != node); |
f5596c94 | 499 | if (!dummy) |
1b81fe1a | 500 | node->p.next = clear_flag(iter); |
f5596c94 | 501 | else |
1b81fe1a | 502 | node->p.next = flag_dummy(clear_flag(iter)); |
f5596c94 MD |
503 | if (is_dummy(iter)) |
504 | new_node = flag_dummy(node); | |
505 | else | |
506 | new_node = node; | |
cc4fcb10 | 507 | if (uatomic_cmpxchg(&iter_prev->p.next, iter, |
f5596c94 | 508 | new_node) != iter) |
273399de | 509 | continue; /* retry */ |
11519af6 | 510 | else |
273399de | 511 | goto gc_end; |
9dba85be MD |
512 | gc_node: |
513 | assert(!is_removed(iter)); | |
f5596c94 MD |
514 | if (is_dummy(iter)) |
515 | new_next = flag_dummy(clear_flag(next)); | |
516 | else | |
517 | new_next = clear_flag(next); | |
518 | (void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next); | |
273399de | 519 | /* retry */ |
464a1ec9 | 520 | } |
273399de MD |
521 | gc_end: |
522 | /* Garbage collect logically removed nodes in the bucket */ | |
24365af7 MD |
523 | index = hash & (t->size - 1); |
524 | order = get_count_order_ulong(index + 1); | |
525 | lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)]; | |
526 | dummy_node = (struct rcu_ht_node *) lookup; | |
f5596c94 | 527 | _ht_gc_bucket(dummy_node, node); |
18117871 | 528 | return node; |
abc490a1 | 529 | } |
464a1ec9 | 530 | |
abc490a1 MD |
531 | static |
532 | int _ht_remove(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node) | |
533 | { | |
273399de | 534 | struct rcu_ht_node *dummy, *next, *old; |
24365af7 | 535 | struct _rcu_ht_node *lookup; |
abc490a1 | 536 | int flagged = 0; |
24365af7 | 537 | unsigned long hash, index, order; |
5e28c532 | 538 | |
7ec59d3b | 539 | /* logically delete the node */ |
cc4fcb10 | 540 | old = rcu_dereference(node->p.next); |
7ec59d3b MD |
541 | do { |
542 | next = old; | |
76412f24 | 543 | if (unlikely(is_removed(next))) |
7ec59d3b | 544 | goto end; |
1b81fe1a | 545 | assert(!is_dummy(next)); |
cc4fcb10 | 546 | old = uatomic_cmpxchg(&node->p.next, next, |
7ec59d3b MD |
547 | flag_removed(next)); |
548 | } while (old != next); | |
549 | ||
550 | /* We performed the (logical) deletion. */ | |
551 | flagged = 1; | |
552 | ||
553 | /* | |
554 | * Ensure that the node is not visible to readers anymore: lookup for | |
273399de MD |
555 | * the node, and remove it (along with any other logically removed node) |
556 | * if found. | |
11519af6 | 557 | */ |
cc4fcb10 | 558 | hash = bit_reverse_ulong(node->p.reverse_hash); |
24365af7 MD |
559 | index = hash & (t->size - 1); |
560 | order = get_count_order_ulong(index + 1); | |
561 | lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)]; | |
562 | dummy = (struct rcu_ht_node *) lookup; | |
273399de | 563 | _ht_gc_bucket(dummy, node); |
2ed95849 | 564 | end: |
11519af6 MD |
565 | /* |
566 | * Only the flagging action indicated that we (and no other) | |
567 | * removed the node from the hash. | |
568 | */ | |
7ec59d3b | 569 | if (flagged) { |
cc4fcb10 | 570 | assert(is_removed(rcu_dereference(node->p.next))); |
11519af6 | 571 | return 0; |
7ec59d3b | 572 | } else |
11519af6 | 573 | return -ENOENT; |
abc490a1 | 574 | } |
2ed95849 | 575 | |
abc490a1 MD |
576 | static |
577 | void init_table(struct rcu_ht *ht, struct rcu_table *t, | |
24365af7 MD |
578 | unsigned long first_order, unsigned long len_order) |
579 | { | |
580 | unsigned long i, end_order; | |
581 | ||
f0c29ed7 | 582 | dbg_printf("init table: first_order %lu end_order %lu\n", |
24365af7 MD |
583 | first_order, first_order + len_order); |
584 | end_order = first_order + len_order; | |
585 | t->size = !first_order ? 0 : (1UL << (first_order - 1)); | |
586 | for (i = first_order; i < end_order; i++) { | |
587 | unsigned long j, len; | |
588 | ||
589 | len = !i ? 1 : 1UL << (i - 1); | |
f0c29ed7 | 590 | dbg_printf("init order %lu len: %lu\n", i, len); |
24365af7 MD |
591 | t->tbl[i] = calloc(len, sizeof(struct _rcu_ht_node)); |
592 | for (j = 0; j < len; j++) { | |
f0c29ed7 | 593 | dbg_printf("init entry: i %lu j %lu hash %lu\n", |
24365af7 MD |
594 | i, j, !i ? 0 : (1UL << (i - 1)) + j); |
595 | struct rcu_ht_node *new_node = | |
596 | (struct rcu_ht_node *) &t->tbl[i][j]; | |
597 | new_node->p.reverse_hash = | |
598 | bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j); | |
599 | (void) _ht_add(ht, t, new_node, 0, 1); | |
33c7c748 MD |
600 | if (CMM_LOAD_SHARED(ht->in_progress_destroy)) |
601 | break; | |
24365af7 MD |
602 | } |
603 | /* Update table size */ | |
604 | t->size = !i ? 1 : (1UL << i); | |
f0c29ed7 | 605 | dbg_printf("init new size: %lu\n", t->size); |
33c7c748 MD |
606 | if (CMM_LOAD_SHARED(ht->in_progress_destroy)) |
607 | break; | |
abc490a1 | 608 | } |
24365af7 | 609 | t->resize_target = t->size; |
11519af6 | 610 | t->resize_initiated = 0; |
2ed95849 MD |
611 | } |
612 | ||
abc490a1 | 613 | struct rcu_ht *ht_new(ht_hash_fct hash_fct, |
732ad076 MD |
614 | ht_compare_fct compare_fct, |
615 | unsigned long hash_seed, | |
abc490a1 MD |
616 | unsigned long init_size, |
617 | void (*ht_call_rcu)(struct rcu_head *head, | |
618 | void (*func)(struct rcu_head *head))) | |
619 | { | |
620 | struct rcu_ht *ht; | |
24365af7 | 621 | unsigned long order; |
abc490a1 MD |
622 | |
623 | ht = calloc(1, sizeof(struct rcu_ht)); | |
624 | ht->hash_fct = hash_fct; | |
732ad076 MD |
625 | ht->compare_fct = compare_fct; |
626 | ht->hash_seed = hash_seed; | |
f000907d | 627 | ht->ht_call_rcu = ht_call_rcu; |
848d4088 | 628 | ht->in_progress_resize = 0; |
abc490a1 MD |
629 | /* this mutex should not nest in read-side C.S. */ |
630 | pthread_mutex_init(&ht->resize_mutex, NULL); | |
24365af7 | 631 | order = get_count_order_ulong(max(init_size, 1)) + 1; |
abc490a1 | 632 | ht->t = calloc(1, sizeof(struct rcu_table) |
24365af7 | 633 | + (order * sizeof(struct _rcu_ht_node *))); |
abc490a1 | 634 | ht->t->size = 0; |
f000907d | 635 | pthread_mutex_lock(&ht->resize_mutex); |
24365af7 | 636 | init_table(ht, ht->t, 0, order); |
f000907d | 637 | pthread_mutex_unlock(&ht->resize_mutex); |
abc490a1 MD |
638 | return ht; |
639 | } | |
640 | ||
732ad076 | 641 | struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key, size_t key_len) |
2ed95849 | 642 | { |
395270b6 | 643 | struct rcu_table *t; |
1b81fe1a | 644 | struct rcu_ht_node *node, *next; |
24365af7 MD |
645 | struct _rcu_ht_node *lookup; |
646 | unsigned long hash, reverse_hash, index, order; | |
2ed95849 | 647 | |
732ad076 | 648 | hash = ht->hash_fct(key, key_len, ht->hash_seed); |
abc490a1 | 649 | reverse_hash = bit_reverse_ulong(hash); |
464a1ec9 | 650 | |
395270b6 | 651 | t = rcu_dereference(ht->t); |
24365af7 MD |
652 | index = hash & (t->size - 1); |
653 | order = get_count_order_ulong(index + 1); | |
654 | lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)]; | |
f0c29ed7 | 655 | dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n", |
24365af7 MD |
656 | hash, index, order, index & ((1UL << (order - 1)) - 1)); |
657 | node = (struct rcu_ht_node *) lookup; | |
2ed95849 | 658 | for (;;) { |
abc490a1 MD |
659 | if (unlikely(!node)) |
660 | break; | |
cc4fcb10 | 661 | if (unlikely(node->p.reverse_hash > reverse_hash)) { |
abc490a1 MD |
662 | node = NULL; |
663 | break; | |
2ed95849 | 664 | } |
1b81fe1a MD |
665 | next = rcu_dereference(node->p.next); |
666 | if (likely(!is_removed(next)) | |
667 | && !is_dummy(next) | |
49c2e2d6 | 668 | && likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) { |
273399de | 669 | break; |
2ed95849 | 670 | } |
1b81fe1a | 671 | node = clear_flag(next); |
2ed95849 | 672 | } |
1b81fe1a | 673 | assert(!node || !is_dummy(rcu_dereference(node->p.next))); |
abc490a1 MD |
674 | return node; |
675 | } | |
e0ba718a | 676 | |
f000907d | 677 | void ht_add(struct rcu_ht *ht, struct rcu_ht_node *node) |
abc490a1 MD |
678 | { |
679 | struct rcu_table *t; | |
49c2e2d6 | 680 | unsigned long hash; |
ab7d5fc6 | 681 | |
49c2e2d6 | 682 | hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed); |
cc4fcb10 | 683 | node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash); |
2ed95849 | 684 | |
abc490a1 | 685 | t = rcu_dereference(ht->t); |
f5596c94 | 686 | (void) _ht_add(ht, t, node, 0, 0); |
3eca1b8c MD |
687 | } |
688 | ||
18117871 | 689 | struct rcu_ht_node *ht_add_unique(struct rcu_ht *ht, struct rcu_ht_node *node) |
3eca1b8c MD |
690 | { |
691 | struct rcu_table *t; | |
49c2e2d6 | 692 | unsigned long hash; |
3eca1b8c | 693 | |
49c2e2d6 | 694 | hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed); |
cc4fcb10 | 695 | node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash); |
3eca1b8c MD |
696 | |
697 | t = rcu_dereference(ht->t); | |
f5596c94 | 698 | return _ht_add(ht, t, node, 1, 0); |
2ed95849 MD |
699 | } |
700 | ||
abc490a1 | 701 | int ht_remove(struct rcu_ht *ht, struct rcu_ht_node *node) |
2ed95849 | 702 | { |
abc490a1 MD |
703 | struct rcu_table *t; |
704 | ||
705 | t = rcu_dereference(ht->t); | |
abc490a1 | 706 | return _ht_remove(ht, t, node); |
2ed95849 | 707 | } |
ab7d5fc6 | 708 | |
abc490a1 MD |
709 | static |
710 | int ht_delete_dummy(struct rcu_ht *ht) | |
674f7a69 | 711 | { |
395270b6 | 712 | struct rcu_table *t; |
abc490a1 | 713 | struct rcu_ht_node *node; |
24365af7 MD |
714 | struct _rcu_ht_node *lookup; |
715 | unsigned long order, i; | |
674f7a69 | 716 | |
abc490a1 MD |
717 | t = ht->t; |
718 | /* Check that the table is empty */ | |
24365af7 MD |
719 | lookup = &t->tbl[0][0]; |
720 | node = (struct rcu_ht_node *) lookup; | |
abc490a1 | 721 | do { |
1b81fe1a MD |
722 | node = clear_flag(node)->p.next; |
723 | if (!is_dummy(node)) | |
abc490a1 | 724 | return -EPERM; |
273399de | 725 | assert(!is_removed(node)); |
a2974903 | 726 | } while (clear_flag(node)); |
abc490a1 | 727 | /* Internal sanity check: all nodes left should be dummy */ |
24365af7 MD |
728 | for (order = 0; order < get_count_order_ulong(t->size) + 1; order++) { |
729 | unsigned long len; | |
730 | ||
731 | len = !order ? 1 : 1UL << (order - 1); | |
732 | for (i = 0; i < len; i++) { | |
f0c29ed7 | 733 | dbg_printf("delete order %lu i %lu hash %lu\n", |
24365af7 MD |
734 | order, i, |
735 | bit_reverse_ulong(t->tbl[order][i].reverse_hash)); | |
736 | assert(is_dummy(t->tbl[order][i].next)); | |
737 | } | |
738 | free(t->tbl[order]); | |
674f7a69 | 739 | } |
abc490a1 | 740 | return 0; |
674f7a69 MD |
741 | } |
742 | ||
743 | /* | |
744 | * Should only be called when no more concurrent readers nor writers can | |
745 | * possibly access the table. | |
746 | */ | |
5e28c532 | 747 | int ht_destroy(struct rcu_ht *ht) |
674f7a69 | 748 | { |
5e28c532 MD |
749 | int ret; |
750 | ||
848d4088 | 751 | /* Wait for in-flight resize operations to complete */ |
33c7c748 | 752 | CMM_STORE_SHARED(ht->in_progress_destroy, 1); |
848d4088 MD |
753 | while (uatomic_read(&ht->in_progress_resize)) |
754 | poll(NULL, 0, 100); /* wait for 100ms */ | |
abc490a1 MD |
755 | ret = ht_delete_dummy(ht); |
756 | if (ret) | |
757 | return ret; | |
395270b6 | 758 | free(ht->t); |
674f7a69 | 759 | free(ht); |
5e28c532 | 760 | return ret; |
674f7a69 MD |
761 | } |
762 | ||
273399de MD |
763 | void ht_count_nodes(struct rcu_ht *ht, |
764 | unsigned long *count, | |
765 | unsigned long *removed) | |
766 | { | |
767 | struct rcu_table *t; | |
768 | struct rcu_ht_node *node, *next; | |
24365af7 MD |
769 | struct _rcu_ht_node *lookup; |
770 | unsigned long nr_dummy = 0; | |
273399de MD |
771 | |
772 | *count = 0; | |
773 | *removed = 0; | |
774 | ||
775 | t = rcu_dereference(ht->t); | |
24365af7 MD |
776 | /* Count non-dummy nodes in the table */ |
777 | lookup = &t->tbl[0][0]; | |
778 | node = (struct rcu_ht_node *) lookup; | |
273399de | 779 | do { |
cc4fcb10 | 780 | next = rcu_dereference(node->p.next); |
273399de | 781 | if (is_removed(next)) { |
1b81fe1a | 782 | assert(!is_dummy(next)); |
273399de | 783 | (*removed)++; |
1b81fe1a | 784 | } else if (!is_dummy(next)) |
273399de | 785 | (*count)++; |
24365af7 MD |
786 | else |
787 | (nr_dummy)++; | |
273399de MD |
788 | node = clear_flag(next); |
789 | } while (node); | |
f0c29ed7 | 790 | dbg_printf("number of dummy nodes: %lu\n", nr_dummy); |
273399de MD |
791 | } |
792 | ||
abc490a1 MD |
793 | static |
794 | void ht_free_table_cb(struct rcu_head *head) | |
795 | { | |
796 | struct rcu_table *t = | |
797 | caa_container_of(head, struct rcu_table, head); | |
798 | free(t); | |
799 | } | |
800 | ||
801 | /* called with resize mutex held */ | |
802 | static | |
803 | void _do_ht_resize(struct rcu_ht *ht) | |
464a1ec9 | 804 | { |
24365af7 | 805 | unsigned long new_size, old_size, old_order, new_order; |
395270b6 | 806 | struct rcu_table *new_t, *old_t; |
464a1ec9 | 807 | |
395270b6 MD |
808 | old_t = ht->t; |
809 | old_size = old_t->size; | |
24365af7 | 810 | old_order = get_count_order_ulong(old_size) + 1; |
464a1ec9 | 811 | |
f9830efd | 812 | new_size = CMM_LOAD_SHARED(old_t->resize_target); |
abc490a1 | 813 | if (old_size == new_size) |
464a1ec9 | 814 | return; |
24365af7 | 815 | new_order = get_count_order_ulong(new_size) + 1; |
f0c29ed7 | 816 | dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", |
df03fab8 | 817 | old_size, old_order, new_size, new_order); |
f000907d | 818 | new_t = malloc(sizeof(struct rcu_table) |
24365af7 | 819 | + (new_order * sizeof(struct _rcu_ht_node *))); |
f000907d MD |
820 | assert(new_size > old_size); |
821 | memcpy(&new_t->tbl, &old_t->tbl, | |
24365af7 MD |
822 | old_order * sizeof(struct _rcu_ht_node *)); |
823 | init_table(ht, new_t, old_order, new_order - old_order); | |
f000907d MD |
824 | /* Changing table and size atomically wrt lookups */ |
825 | rcu_assign_pointer(ht->t, new_t); | |
826 | ht->ht_call_rcu(&old_t->head, ht_free_table_cb); | |
464a1ec9 MD |
827 | } |
828 | ||
abc490a1 | 829 | static |
f9830efd MD |
830 | unsigned long resize_target_update(struct rcu_table *t, |
831 | int growth_order) | |
464a1ec9 | 832 | { |
f9830efd MD |
833 | return _uatomic_max(&t->resize_target, |
834 | t->size << growth_order); | |
464a1ec9 MD |
835 | } |
836 | ||
464a1ec9 MD |
837 | void ht_resize(struct rcu_ht *ht, int growth) |
838 | { | |
f9830efd MD |
839 | struct rcu_table *t = rcu_dereference(ht->t); |
840 | unsigned long target_size; | |
841 | ||
f0c29ed7 MD |
842 | if (growth < 0) { |
843 | /* | |
844 | * Silently refuse to shrink hash table. (not supported) | |
845 | */ | |
846 | dbg_printf("shrinking hash table not supported.\n"); | |
847 | return; | |
848 | } | |
849 | ||
f9830efd MD |
850 | target_size = resize_target_update(t, growth); |
851 | if (t->size < target_size) { | |
11519af6 | 852 | CMM_STORE_SHARED(t->resize_initiated, 1); |
f9830efd MD |
853 | pthread_mutex_lock(&ht->resize_mutex); |
854 | _do_ht_resize(ht); | |
855 | pthread_mutex_unlock(&ht->resize_mutex); | |
856 | } | |
abc490a1 | 857 | } |
464a1ec9 | 858 | |
abc490a1 MD |
859 | static |
860 | void do_resize_cb(struct rcu_head *head) | |
861 | { | |
862 | struct rcu_resize_work *work = | |
863 | caa_container_of(head, struct rcu_resize_work, head); | |
864 | struct rcu_ht *ht = work->ht; | |
865 | ||
866 | pthread_mutex_lock(&ht->resize_mutex); | |
867 | _do_ht_resize(ht); | |
868 | pthread_mutex_unlock(&ht->resize_mutex); | |
869 | free(work); | |
848d4088 MD |
870 | cmm_smp_mb(); /* finish resize before decrement */ |
871 | uatomic_dec(&ht->in_progress_resize); | |
464a1ec9 MD |
872 | } |
873 | ||
abc490a1 | 874 | static |
f000907d | 875 | void ht_resize_lazy(struct rcu_ht *ht, struct rcu_table *t, int growth) |
ab7d5fc6 | 876 | { |
abc490a1 | 877 | struct rcu_resize_work *work; |
f9830efd | 878 | unsigned long target_size; |
abc490a1 | 879 | |
f9830efd | 880 | target_size = resize_target_update(t, growth); |
11519af6 | 881 | if (!CMM_LOAD_SHARED(t->resize_initiated) && t->size < target_size) { |
848d4088 MD |
882 | uatomic_inc(&ht->in_progress_resize); |
883 | cmm_smp_mb(); /* increment resize count before calling it */ | |
f9830efd MD |
884 | work = malloc(sizeof(*work)); |
885 | work->ht = ht; | |
886 | ht->ht_call_rcu(&work->head, do_resize_cb); | |
11519af6 | 887 | CMM_STORE_SHARED(t->resize_initiated, 1); |
f9830efd | 888 | } |
ab7d5fc6 | 889 | } |