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b45a45b9 MD |
1 | /* |
2 | * rcuja/rcuja-range.c | |
3 | * | |
4 | * Userspace RCU library - RCU Judy Array Range Support | |
5 | * | |
6 | * Copyright 2012-2013 - 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 <string.h> | |
28 | #include <assert.h> | |
29 | #include <pthread.h> | |
30 | #include <urcu/rcuja.h> | |
31 | #include <urcu/compiler.h> | |
32 | #include <urcu/arch.h> | |
33 | #include <urcu-pointer.h> | |
34 | #include <urcu/uatomic.h> | |
35 | #include <urcu/rcuja-range.h> | |
36 | #include <urcu-flavor.h> | |
37 | ||
38 | #include "rcuja-internal.h" | |
39 | ||
40 | /* | |
41 | * Discussion about order of lookup/lock vs allocated node deletion. | |
42 | * | |
43 | * - If node deletion returns before call to | |
44 | * cds_ja_range_lookup(), the node will not be found by lookup. | |
45 | * - If node deletion is called after cds_ja_range_lock() returns a | |
46 | * non-NULL range, the deletion will wait until the lock is released | |
47 | * before it takes place. | |
48 | * - If node deletion call/return overlaps with the call to | |
49 | * cds_ja_range_lookup() and return from cds_ja_range_lock(), the node | |
50 | * may or may not be found by each of cds_ja_range_lookup() and | |
51 | * cds_ja_range_lock(). | |
52 | */ | |
53 | ||
54 | /* | |
55 | * Discussion about order of lookup/lock vs allocated node add. Assuming | |
56 | * no concurrent delete. | |
57 | * | |
58 | * - If node add returns before call to | |
59 | * cds_ja_range_lookup(), the node will be found by lookup. | |
60 | * - If node add is called after cds_ja_range_lookup returns, the node | |
61 | * will not be found by lookup. | |
62 | * - If node add call/return overlaps with the call to and return from | |
63 | * cds_ja_range_lookup(), the node may or may not be found. | |
64 | * - If node add call/return overlaps with call to cds_ja_range_lookup() | |
65 | * and return from cds_ja_range_lock(), in the specific case where | |
66 | * cds_ja_range_lookup() _does_ succeed, then cds_ja_range_lock() will | |
67 | * succeed (still assuming no concurrent deletion). | |
68 | */ | |
69 | ||
c34bfad2 MD |
70 | /* |
71 | * Discussion: concurrent deletion of contiguous allocated ranges. | |
72 | * | |
73 | * Ensuring that merge of contiguous free ranges is always performed, we | |
74 | * need to ensure locking of concurrent removal of contiguous allocated | |
75 | * ranges one with respect to another. This is done by locking the | |
76 | * ranges prior to and after the range to remove, even if that range is | |
77 | * allocated. This serializes removal of contiguous ranges. The only | |
78 | * cases for which there is no range to lock is when removing an | |
79 | * allocated range starting at 0, and/or ending at the end of the key | |
80 | * space. | |
81 | */ | |
82 | ||
b45a45b9 MD |
83 | /* |
84 | * Discussion of the type state transitions. | |
85 | * | |
86 | * State transitions of "type" always go from either: | |
87 | * | |
88 | * CDS_JA_RANGE_FREE -> CDS_JA_RANGE_REMOVED | |
89 | * or | |
90 | * CDS_JA_RANGE_ALLOCATED -> CDS_JA_RANGE_REMOVED | |
91 | * | |
92 | * A range type never changes otherwise. | |
93 | */ | |
94 | ||
678624e7 | 95 | #define CDS_JA_RANGE_KEY_BITS 64 |
b45a45b9 | 96 | |
fe8ad3da MD |
97 | enum cds_ja_range_type { |
98 | CDS_JA_RANGE_ALLOCATED, | |
99 | CDS_JA_RANGE_FREE, | |
100 | CDS_JA_RANGE_REMOVED, | |
101 | }; | |
102 | ||
103 | /* | |
104 | * Range goes from start (inclusive) to end (inclusive). | |
105 | * Range start is used as node key in the Judy array. | |
106 | */ | |
107 | struct cds_ja_range { | |
108 | uint64_t end; | |
109 | struct cds_ja_node ja_node; | |
110 | pthread_mutex_t lock; | |
111 | void *priv; | |
112 | enum cds_ja_range_type type; | |
113 | ||
114 | /* not required on lookup fast-path */ | |
115 | uint64_t start; | |
116 | struct rcu_head head; | |
117 | }; | |
118 | ||
b45a45b9 MD |
119 | struct cds_ja_range *cds_ja_range_lookup(struct cds_ja *ja, uint64_t key) |
120 | { | |
121 | struct cds_ja_node *node, *last_node; | |
122 | struct cds_ja_range *range; | |
123 | ||
124 | node = cds_ja_lookup_below_equal(ja, key, NULL); | |
125 | assert(node); | |
126 | /* | |
127 | * Get the last of duplicate chain. Adding a node to Judy array | |
128 | * duplicates inserts them at the end of the chain. | |
129 | */ | |
130 | cds_ja_for_each_duplicate_rcu(node) | |
131 | last_node = node; | |
132 | range = caa_container_of(last_node, struct cds_ja_range, ja_node); | |
133 | /* | |
134 | * If last node in the duplicates is removed or free, we can | |
135 | * consider that either a removal or add operation is in | |
136 | * progress, or removal is the last completed operation to | |
137 | * update this range. We can therefore consider that this area | |
138 | * is not allocated. | |
139 | */ | |
140 | if (range->type != CDS_JA_RANGE_ALLOCATED) | |
141 | return NULL; | |
142 | /* | |
143 | * We found an allocated range. We can return it for use with | |
7c74dcc7 | 144 | * RCU read-side protection for existence. However, we have no |
b45a45b9 MD |
145 | * mutual exclusion against removal at this point. |
146 | */ | |
147 | return range; | |
148 | } | |
149 | ||
150 | /* | |
151 | * Provide mutual exclusion against removal. | |
152 | */ | |
153 | struct cds_ja_range *cds_ja_range_lock(struct cds_ja_range *range) | |
154 | { | |
155 | pthread_mutex_lock(&range->lock); | |
156 | ||
157 | if (range->type == CDS_JA_RANGE_REMOVED) | |
158 | goto removed; | |
159 | return range; | |
160 | ||
161 | removed: | |
162 | pthread_mutex_unlock(&range->lock); | |
163 | return NULL; | |
164 | } | |
165 | ||
166 | void cds_ja_range_unlock(struct cds_ja_range *range) | |
167 | { | |
168 | pthread_mutex_unlock(&range->lock); | |
169 | } | |
170 | ||
171 | static | |
172 | struct cds_ja_range *range_create( | |
173 | uint64_t start, /* inclusive */ | |
174 | uint64_t end, /* inclusive */ | |
fe8ad3da | 175 | void *priv, |
b45a45b9 MD |
176 | enum cds_ja_range_type type) |
177 | { | |
178 | struct cds_ja_range *range; | |
179 | ||
180 | range = calloc(sizeof(*range), 1); | |
181 | if (!range) | |
182 | return NULL; | |
183 | range->start = start; | |
184 | range->end = end; | |
fe8ad3da | 185 | range->priv = priv; |
b45a45b9 MD |
186 | range->type = type; |
187 | pthread_mutex_init(&range->lock, NULL); | |
188 | return range; | |
189 | } | |
190 | ||
191 | static | |
192 | void free_range_cb(struct rcu_head *head) | |
193 | { | |
194 | struct cds_ja_range *range = | |
195 | caa_container_of(head, struct cds_ja_range, head); | |
196 | free(range); | |
197 | } | |
198 | ||
199 | static | |
200 | void free_range(struct cds_ja_range *range) | |
201 | { | |
202 | free(range); | |
203 | } | |
204 | ||
205 | static | |
206 | void rcu_free_range(struct cds_ja *ja, struct cds_ja_range *range) | |
207 | { | |
208 | cds_lfht_rcu_flavor(ja->ht)->update_call_rcu(&range->head, | |
209 | free_range_cb); | |
210 | } | |
211 | ||
212 | struct cds_ja_range *cds_ja_range_add(struct cds_ja *ja, | |
213 | uint64_t start, /* inclusive */ | |
fe8ad3da MD |
214 | uint64_t end, /* inclusive */ |
215 | void *priv) | |
b45a45b9 MD |
216 | { |
217 | struct cds_ja_node *old_node, *old_node_end; | |
218 | struct cds_ja_range *old_range, *old_range_end, *new_range, *ranges[3]; | |
219 | unsigned int nr_ranges, i; | |
220 | int ret; | |
221 | ||
222 | retry: | |
223 | /* | |
224 | * Find if requested range is entirely contained within a single | |
225 | * free range. | |
226 | */ | |
227 | old_node = cds_ja_lookup_below_equal(ja, start, NULL); | |
228 | assert(old_node); | |
229 | ||
230 | old_range = caa_container_of(old_node, struct cds_ja_range, ja_node); | |
231 | switch (CMM_LOAD_SHARED(old_range->type)) { | |
232 | case CDS_JA_RANGE_ALLOCATED: | |
233 | return NULL; | |
234 | case CDS_JA_RANGE_FREE: | |
235 | break; | |
236 | case CDS_JA_RANGE_REMOVED: | |
237 | goto retry; | |
238 | } | |
239 | ||
240 | old_node_end = cds_ja_lookup_below_equal(ja, end, NULL); | |
241 | assert(old_node_end); | |
242 | old_range_end = caa_container_of(old_node_end, | |
243 | struct cds_ja_range, ja_node); | |
244 | if (old_range_end != old_range) { | |
245 | switch (CMM_LOAD_SHARED(old_range->type)) { | |
246 | case CDS_JA_RANGE_ALLOCATED: | |
247 | case CDS_JA_RANGE_FREE: /* fall-through */ | |
b45a45b9 MD |
248 | return NULL; |
249 | case CDS_JA_RANGE_REMOVED: | |
250 | goto retry; | |
251 | } | |
252 | } | |
253 | ||
254 | pthread_mutex_lock(&old_range->lock); | |
255 | ||
256 | if (old_range->type == CDS_JA_RANGE_REMOVED) { | |
257 | pthread_mutex_unlock(&old_range->lock); | |
258 | goto retry; | |
259 | } | |
260 | ||
261 | /* Create replacement ranges: at most 2 free and 1 allocated */ | |
262 | if (start == old_range->start) { | |
263 | if (end == old_range->end) { | |
264 | /* 1 range */ | |
265 | ranges[0] = new_range = range_create(start, end, | |
fe8ad3da | 266 | priv, CDS_JA_RANGE_ALLOCATED); |
b45a45b9 MD |
267 | nr_ranges = 1; |
268 | } else { | |
269 | /* 2 ranges */ | |
270 | ranges[0] = new_range = range_create(start, end, | |
fe8ad3da | 271 | priv, CDS_JA_RANGE_ALLOCATED); |
b45a45b9 | 272 | ranges[1] = range_create(end + 1, old_range->end, |
fe8ad3da | 273 | NULL, CDS_JA_RANGE_FREE); |
b45a45b9 MD |
274 | nr_ranges = 2; |
275 | } | |
276 | } else { | |
277 | if (end == old_range->end) { | |
278 | /* 2 ranges */ | |
279 | ranges[0] = range_create(old_range->start, start - 1, | |
fe8ad3da | 280 | NULL, CDS_JA_RANGE_FREE); |
b45a45b9 | 281 | ranges[1] = new_range = range_create(start, end, |
fe8ad3da | 282 | priv, CDS_JA_RANGE_ALLOCATED); |
b45a45b9 MD |
283 | nr_ranges = 2; |
284 | } else { | |
285 | /* 3 ranges */ | |
286 | ranges[0] = range_create(old_range->start, start - 1, | |
fe8ad3da | 287 | NULL, CDS_JA_RANGE_FREE); |
b45a45b9 | 288 | ranges[1] = new_range = range_create(start, end, |
fe8ad3da | 289 | priv, CDS_JA_RANGE_ALLOCATED); |
b45a45b9 | 290 | ranges[2] = range_create(end + 1, old_range->end, |
fe8ad3da | 291 | NULL, CDS_JA_RANGE_FREE); |
b45a45b9 MD |
292 | nr_ranges = 3; |
293 | } | |
294 | } | |
295 | ||
296 | /* Add replacement ranges to Judy array */ | |
297 | for (i = 0; i < nr_ranges; i++) { | |
298 | ret = cds_ja_add(ja, ranges[i]->start, &ranges[i]->ja_node); | |
299 | assert(!ret); | |
300 | } | |
301 | ||
302 | /* | |
303 | * We add replacement ranges _before_ removing old ranges, so | |
304 | * concurrent traversals will always see one or the other. This | |
305 | * is OK because we temporarily have a duplicate key, and Judy | |
306 | * arrays provide key existence guarantee for lookups performed | |
307 | * concurrently with add followed by del of duplicate keys. | |
308 | */ | |
309 | ||
310 | /* Remove old free range */ | |
311 | ret = cds_ja_del(ja, old_range->start, &old_range->ja_node); | |
312 | assert(!ret); | |
313 | old_range->type = CDS_JA_RANGE_REMOVED; | |
314 | pthread_mutex_unlock(&old_range->lock); | |
315 | ||
316 | rcu_free_range(ja, old_range); | |
317 | ||
318 | return new_range; | |
319 | } | |
320 | ||
321 | int cds_ja_range_del(struct cds_ja *ja, struct cds_ja_range *range) | |
322 | { | |
323 | struct cds_ja_node *prev_node, *next_node; | |
c34bfad2 MD |
324 | struct cds_ja_range *new_range; |
325 | struct cds_ja_range *merge_ranges[3], *lock_ranges[3]; | |
326 | unsigned int nr_merge, nr_lock, i; | |
b45a45b9 MD |
327 | uint64_t start, end; |
328 | int ret; | |
329 | ||
330 | retry: | |
331 | nr_merge = 0; | |
c34bfad2 | 332 | nr_lock = 0; |
b45a45b9 | 333 | prev_node = cds_ja_lookup_below_equal(ja, range->start - 1, NULL); |
c34bfad2 MD |
334 | if (prev_node) { |
335 | struct cds_ja_range *prev_range; | |
b45a45b9 | 336 | |
c34bfad2 MD |
337 | prev_range = caa_container_of(prev_node, |
338 | struct cds_ja_range, ja_node); | |
339 | lock_ranges[nr_lock++] = prev_range; | |
340 | if (prev_range->type != CDS_JA_RANGE_ALLOCATED) | |
341 | merge_ranges[nr_merge++] = prev_range; | |
342 | } | |
343 | ||
344 | lock_ranges[nr_lock++] = range; | |
b45a45b9 MD |
345 | merge_ranges[nr_merge++] = range; |
346 | ||
347 | next_node = cds_ja_lookup_above_equal(ja, range->end + 1, NULL); | |
c34bfad2 MD |
348 | if (next_node) { |
349 | struct cds_ja_range *next_range; | |
350 | ||
351 | next_range = caa_container_of(next_node, | |
352 | struct cds_ja_range, ja_node); | |
353 | lock_ranges[nr_lock++] = next_range; | |
354 | if (next_range->type != CDS_JA_RANGE_ALLOCATED) | |
355 | merge_ranges[nr_merge++] = next_range; | |
356 | } | |
b45a45b9 MD |
357 | |
358 | /* Acquire locks in increasing key order for range merge */ | |
c34bfad2 MD |
359 | for (i = 0; i < nr_lock; i++) |
360 | pthread_mutex_lock(&lock_ranges[i]->lock); | |
b45a45b9 | 361 | /* Ensure they are valid */ |
c34bfad2 MD |
362 | for (i = 0; i < nr_lock; i++) { |
363 | if (lock_ranges[i]->type == CDS_JA_RANGE_REMOVED) | |
b45a45b9 MD |
364 | goto unlock_retry; |
365 | } | |
366 | ||
367 | /* Create new free range */ | |
368 | start = merge_ranges[0]->start; | |
369 | end = merge_ranges[nr_merge - 1]->end; | |
fe8ad3da | 370 | new_range = range_create(start, end, NULL, CDS_JA_RANGE_FREE); |
b45a45b9 MD |
371 | ret = cds_ja_add(ja, start, &new_range->ja_node); |
372 | assert(!ret); | |
373 | ||
374 | /* Remove old ranges */ | |
375 | for (i = 0; i < nr_merge; i++) { | |
376 | ret = cds_ja_del(ja, merge_ranges[i]->start, | |
377 | &merge_ranges[i]->ja_node); | |
378 | assert(!ret); | |
379 | merge_ranges[i]->type = CDS_JA_RANGE_REMOVED; | |
b45a45b9 | 380 | } |
c34bfad2 MD |
381 | for (i = 0; i < nr_lock; i++) |
382 | pthread_mutex_unlock(&lock_ranges[i]->lock); | |
383 | /* Free old merged ranges */ | |
384 | for (i = 0; i < nr_merge; i++) | |
385 | rcu_free_range(ja, merge_ranges[i]); | |
b45a45b9 MD |
386 | |
387 | return 0; | |
388 | ||
389 | /* retry paths */ | |
390 | unlock_retry: | |
c34bfad2 MD |
391 | for (i = 0; i < nr_lock; i++) |
392 | pthread_mutex_unlock(&lock_ranges[i]->lock); | |
b45a45b9 MD |
393 | goto retry; |
394 | } | |
395 | ||
678624e7 | 396 | struct cds_ja *_cds_ja_range_new(const struct rcu_flavor_struct *flavor) |
b45a45b9 | 397 | { |
b45a45b9 | 398 | struct cds_ja_range *range; |
678624e7 | 399 | struct cds_ja *ja; |
b45a45b9 MD |
400 | int ret; |
401 | ||
678624e7 MD |
402 | ja = _cds_ja_new(CDS_JA_RANGE_KEY_BITS, flavor); |
403 | if (!ja) | |
404 | return NULL; | |
fe8ad3da | 405 | range = range_create(0, UINT64_MAX, NULL, CDS_JA_RANGE_FREE); |
b45a45b9 | 406 | if (!range) |
678624e7 | 407 | goto free_ja; |
dd1da0cb | 408 | cds_lfht_rcu_flavor(ja->ht)->read_lock(); |
b45a45b9 | 409 | ret = cds_ja_add(ja, 0, &range->ja_node); |
dd1da0cb | 410 | cds_lfht_rcu_flavor(ja->ht)->read_unlock(); |
678624e7 MD |
411 | if (ret) |
412 | goto free_range; | |
413 | return ja; | |
414 | ||
415 | free_range: | |
416 | free_range(range); | |
417 | free_ja: | |
418 | ret = cds_ja_destroy(ja); | |
419 | assert(!ret); | |
420 | return NULL; | |
b45a45b9 MD |
421 | } |
422 | ||
fe8ad3da MD |
423 | int cds_ja_range_destroy(struct cds_ja *ja, |
424 | void (*free_priv)(void *ptr)) | |
b45a45b9 MD |
425 | { |
426 | uint64_t key; | |
427 | struct cds_ja_node *ja_node; | |
428 | int ret = 0; | |
429 | ||
dd1da0cb | 430 | cds_lfht_rcu_flavor(ja->ht)->read_lock(); |
b45a45b9 MD |
431 | cds_ja_for_each_key_rcu(ja, key, ja_node) { |
432 | struct cds_ja_node *tmp_node; | |
433 | ||
434 | cds_ja_for_each_duplicate_safe_rcu(ja_node, tmp_node) { | |
435 | struct cds_ja_range *range; | |
436 | ||
437 | range = caa_container_of(ja_node, | |
438 | struct cds_ja_range, ja_node); | |
439 | ret = cds_ja_del(ja, key, &range->ja_node); | |
678624e7 MD |
440 | if (ret) |
441 | goto error; | |
fe8ad3da MD |
442 | if (free_priv) |
443 | free_priv(range->priv); | |
b45a45b9 MD |
444 | /* Alone using Judy array, OK to free now */ |
445 | free_range(range); | |
446 | } | |
447 | } | |
dd1da0cb | 448 | cds_lfht_rcu_flavor(ja->ht)->read_unlock(); |
678624e7 MD |
449 | return cds_ja_destroy(ja); |
450 | ||
451 | error: | |
dd1da0cb | 452 | cds_lfht_rcu_flavor(ja->ht)->read_unlock(); |
b45a45b9 MD |
453 | return ret; |
454 | } |