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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 | ||
95 | ||
96 | struct cds_ja_range *cds_ja_range_lookup(struct cds_ja *ja, uint64_t key) | |
97 | { | |
98 | struct cds_ja_node *node, *last_node; | |
99 | struct cds_ja_range *range; | |
100 | ||
101 | node = cds_ja_lookup_below_equal(ja, key, NULL); | |
102 | assert(node); | |
103 | /* | |
104 | * Get the last of duplicate chain. Adding a node to Judy array | |
105 | * duplicates inserts them at the end of the chain. | |
106 | */ | |
107 | cds_ja_for_each_duplicate_rcu(node) | |
108 | last_node = node; | |
109 | range = caa_container_of(last_node, struct cds_ja_range, ja_node); | |
110 | /* | |
111 | * If last node in the duplicates is removed or free, we can | |
112 | * consider that either a removal or add operation is in | |
113 | * progress, or removal is the last completed operation to | |
114 | * update this range. We can therefore consider that this area | |
115 | * is not allocated. | |
116 | */ | |
117 | if (range->type != CDS_JA_RANGE_ALLOCATED) | |
118 | return NULL; | |
119 | /* | |
120 | * We found an allocated range. We can return it for use with | |
7c74dcc7 | 121 | * RCU read-side protection for existence. However, we have no |
b45a45b9 MD |
122 | * mutual exclusion against removal at this point. |
123 | */ | |
124 | return range; | |
125 | } | |
126 | ||
127 | /* | |
128 | * Provide mutual exclusion against removal. | |
129 | */ | |
130 | struct cds_ja_range *cds_ja_range_lock(struct cds_ja_range *range) | |
131 | { | |
132 | pthread_mutex_lock(&range->lock); | |
133 | ||
134 | if (range->type == CDS_JA_RANGE_REMOVED) | |
135 | goto removed; | |
136 | return range; | |
137 | ||
138 | removed: | |
139 | pthread_mutex_unlock(&range->lock); | |
140 | return NULL; | |
141 | } | |
142 | ||
143 | void cds_ja_range_unlock(struct cds_ja_range *range) | |
144 | { | |
145 | pthread_mutex_unlock(&range->lock); | |
146 | } | |
147 | ||
148 | static | |
149 | struct cds_ja_range *range_create( | |
150 | uint64_t start, /* inclusive */ | |
151 | uint64_t end, /* inclusive */ | |
152 | enum cds_ja_range_type type) | |
153 | { | |
154 | struct cds_ja_range *range; | |
155 | ||
156 | range = calloc(sizeof(*range), 1); | |
157 | if (!range) | |
158 | return NULL; | |
159 | range->start = start; | |
160 | range->end = end; | |
161 | range->type = type; | |
162 | pthread_mutex_init(&range->lock, NULL); | |
163 | return range; | |
164 | } | |
165 | ||
166 | static | |
167 | void free_range_cb(struct rcu_head *head) | |
168 | { | |
169 | struct cds_ja_range *range = | |
170 | caa_container_of(head, struct cds_ja_range, head); | |
171 | free(range); | |
172 | } | |
173 | ||
174 | static | |
175 | void free_range(struct cds_ja_range *range) | |
176 | { | |
177 | free(range); | |
178 | } | |
179 | ||
180 | static | |
181 | void rcu_free_range(struct cds_ja *ja, struct cds_ja_range *range) | |
182 | { | |
183 | cds_lfht_rcu_flavor(ja->ht)->update_call_rcu(&range->head, | |
184 | free_range_cb); | |
185 | } | |
186 | ||
187 | struct cds_ja_range *cds_ja_range_add(struct cds_ja *ja, | |
188 | uint64_t start, /* inclusive */ | |
189 | uint64_t end) /* inclusive */ | |
190 | { | |
191 | struct cds_ja_node *old_node, *old_node_end; | |
192 | struct cds_ja_range *old_range, *old_range_end, *new_range, *ranges[3]; | |
193 | unsigned int nr_ranges, i; | |
194 | int ret; | |
195 | ||
196 | retry: | |
197 | /* | |
198 | * Find if requested range is entirely contained within a single | |
199 | * free range. | |
200 | */ | |
201 | old_node = cds_ja_lookup_below_equal(ja, start, NULL); | |
202 | assert(old_node); | |
203 | ||
204 | old_range = caa_container_of(old_node, struct cds_ja_range, ja_node); | |
205 | switch (CMM_LOAD_SHARED(old_range->type)) { | |
206 | case CDS_JA_RANGE_ALLOCATED: | |
207 | return NULL; | |
208 | case CDS_JA_RANGE_FREE: | |
209 | break; | |
210 | case CDS_JA_RANGE_REMOVED: | |
211 | goto retry; | |
212 | } | |
213 | ||
214 | old_node_end = cds_ja_lookup_below_equal(ja, end, NULL); | |
215 | assert(old_node_end); | |
216 | old_range_end = caa_container_of(old_node_end, | |
217 | struct cds_ja_range, ja_node); | |
218 | if (old_range_end != old_range) { | |
219 | switch (CMM_LOAD_SHARED(old_range->type)) { | |
220 | case CDS_JA_RANGE_ALLOCATED: | |
221 | case CDS_JA_RANGE_FREE: /* fall-through */ | |
b45a45b9 MD |
222 | return NULL; |
223 | case CDS_JA_RANGE_REMOVED: | |
224 | goto retry; | |
225 | } | |
226 | } | |
227 | ||
228 | pthread_mutex_lock(&old_range->lock); | |
229 | ||
230 | if (old_range->type == CDS_JA_RANGE_REMOVED) { | |
231 | pthread_mutex_unlock(&old_range->lock); | |
232 | goto retry; | |
233 | } | |
234 | ||
235 | /* Create replacement ranges: at most 2 free and 1 allocated */ | |
236 | if (start == old_range->start) { | |
237 | if (end == old_range->end) { | |
238 | /* 1 range */ | |
239 | ranges[0] = new_range = range_create(start, end, | |
240 | CDS_JA_RANGE_ALLOCATED); | |
241 | nr_ranges = 1; | |
242 | } else { | |
243 | /* 2 ranges */ | |
244 | ranges[0] = new_range = range_create(start, end, | |
245 | CDS_JA_RANGE_ALLOCATED); | |
246 | ranges[1] = range_create(end + 1, old_range->end, | |
247 | CDS_JA_RANGE_FREE); | |
248 | nr_ranges = 2; | |
249 | } | |
250 | } else { | |
251 | if (end == old_range->end) { | |
252 | /* 2 ranges */ | |
253 | ranges[0] = range_create(old_range->start, start - 1, | |
254 | CDS_JA_RANGE_FREE); | |
255 | ranges[1] = new_range = range_create(start, end, | |
256 | CDS_JA_RANGE_ALLOCATED); | |
257 | nr_ranges = 2; | |
258 | } else { | |
259 | /* 3 ranges */ | |
260 | ranges[0] = range_create(old_range->start, start - 1, | |
261 | CDS_JA_RANGE_FREE); | |
262 | ranges[1] = new_range = range_create(start, end, | |
263 | CDS_JA_RANGE_ALLOCATED); | |
264 | ranges[2] = range_create(end + 1, old_range->end, | |
265 | CDS_JA_RANGE_FREE); | |
266 | nr_ranges = 3; | |
267 | } | |
268 | } | |
269 | ||
270 | /* Add replacement ranges to Judy array */ | |
271 | for (i = 0; i < nr_ranges; i++) { | |
272 | ret = cds_ja_add(ja, ranges[i]->start, &ranges[i]->ja_node); | |
273 | assert(!ret); | |
274 | } | |
275 | ||
276 | /* | |
277 | * We add replacement ranges _before_ removing old ranges, so | |
278 | * concurrent traversals will always see one or the other. This | |
279 | * is OK because we temporarily have a duplicate key, and Judy | |
280 | * arrays provide key existence guarantee for lookups performed | |
281 | * concurrently with add followed by del of duplicate keys. | |
282 | */ | |
283 | ||
284 | /* Remove old free range */ | |
285 | ret = cds_ja_del(ja, old_range->start, &old_range->ja_node); | |
286 | assert(!ret); | |
287 | old_range->type = CDS_JA_RANGE_REMOVED; | |
288 | pthread_mutex_unlock(&old_range->lock); | |
289 | ||
290 | rcu_free_range(ja, old_range); | |
291 | ||
292 | return new_range; | |
293 | } | |
294 | ||
295 | int cds_ja_range_del(struct cds_ja *ja, struct cds_ja_range *range) | |
296 | { | |
297 | struct cds_ja_node *prev_node, *next_node; | |
c34bfad2 MD |
298 | struct cds_ja_range *new_range; |
299 | struct cds_ja_range *merge_ranges[3], *lock_ranges[3]; | |
300 | unsigned int nr_merge, nr_lock, i; | |
b45a45b9 MD |
301 | uint64_t start, end; |
302 | int ret; | |
303 | ||
304 | retry: | |
305 | nr_merge = 0; | |
c34bfad2 | 306 | nr_lock = 0; |
b45a45b9 | 307 | prev_node = cds_ja_lookup_below_equal(ja, range->start - 1, NULL); |
c34bfad2 MD |
308 | if (prev_node) { |
309 | struct cds_ja_range *prev_range; | |
b45a45b9 | 310 | |
c34bfad2 MD |
311 | prev_range = caa_container_of(prev_node, |
312 | struct cds_ja_range, ja_node); | |
313 | lock_ranges[nr_lock++] = prev_range; | |
314 | if (prev_range->type != CDS_JA_RANGE_ALLOCATED) | |
315 | merge_ranges[nr_merge++] = prev_range; | |
316 | } | |
317 | ||
318 | lock_ranges[nr_lock++] = range; | |
b45a45b9 MD |
319 | merge_ranges[nr_merge++] = range; |
320 | ||
321 | next_node = cds_ja_lookup_above_equal(ja, range->end + 1, NULL); | |
c34bfad2 MD |
322 | if (next_node) { |
323 | struct cds_ja_range *next_range; | |
324 | ||
325 | next_range = caa_container_of(next_node, | |
326 | struct cds_ja_range, ja_node); | |
327 | lock_ranges[nr_lock++] = next_range; | |
328 | if (next_range->type != CDS_JA_RANGE_ALLOCATED) | |
329 | merge_ranges[nr_merge++] = next_range; | |
330 | } | |
b45a45b9 MD |
331 | |
332 | /* Acquire locks in increasing key order for range merge */ | |
c34bfad2 MD |
333 | for (i = 0; i < nr_lock; i++) |
334 | pthread_mutex_lock(&lock_ranges[i]->lock); | |
b45a45b9 | 335 | /* Ensure they are valid */ |
c34bfad2 MD |
336 | for (i = 0; i < nr_lock; i++) { |
337 | if (lock_ranges[i]->type == CDS_JA_RANGE_REMOVED) | |
b45a45b9 MD |
338 | goto unlock_retry; |
339 | } | |
340 | ||
341 | /* Create new free range */ | |
342 | start = merge_ranges[0]->start; | |
343 | end = merge_ranges[nr_merge - 1]->end; | |
344 | new_range = range_create(start, end, CDS_JA_RANGE_FREE); | |
345 | ret = cds_ja_add(ja, start, &new_range->ja_node); | |
346 | assert(!ret); | |
347 | ||
348 | /* Remove old ranges */ | |
349 | for (i = 0; i < nr_merge; i++) { | |
350 | ret = cds_ja_del(ja, merge_ranges[i]->start, | |
351 | &merge_ranges[i]->ja_node); | |
352 | assert(!ret); | |
353 | merge_ranges[i]->type = CDS_JA_RANGE_REMOVED; | |
b45a45b9 | 354 | } |
c34bfad2 MD |
355 | for (i = 0; i < nr_lock; i++) |
356 | pthread_mutex_unlock(&lock_ranges[i]->lock); | |
357 | /* Free old merged ranges */ | |
358 | for (i = 0; i < nr_merge; i++) | |
359 | rcu_free_range(ja, merge_ranges[i]); | |
b45a45b9 MD |
360 | |
361 | return 0; | |
362 | ||
363 | /* retry paths */ | |
364 | unlock_retry: | |
c34bfad2 MD |
365 | for (i = 0; i < nr_lock; i++) |
366 | pthread_mutex_unlock(&lock_ranges[i]->lock); | |
b45a45b9 MD |
367 | goto retry; |
368 | } | |
369 | ||
370 | int cds_ja_range_init(struct cds_ja *ja) | |
371 | { | |
372 | struct cds_ja_node *node; | |
373 | struct cds_ja_range *range; | |
374 | int ret; | |
375 | ||
376 | /* | |
377 | * Sanity check: should be empty. | |
378 | */ | |
379 | node = cds_ja_lookup_above_equal(ja, 0, NULL); | |
380 | if (node) | |
381 | return -EINVAL; | |
382 | range = range_create(0, UINT64_MAX, CDS_JA_RANGE_FREE); | |
383 | if (!range) | |
384 | return -EINVAL; | |
385 | ret = cds_ja_add(ja, 0, &range->ja_node); | |
386 | return ret; | |
387 | } | |
388 | ||
389 | int cds_ja_range_fini(struct cds_ja *ja) | |
390 | { | |
391 | uint64_t key; | |
392 | struct cds_ja_node *ja_node; | |
393 | int ret = 0; | |
394 | ||
395 | cds_ja_for_each_key_rcu(ja, key, ja_node) { | |
396 | struct cds_ja_node *tmp_node; | |
397 | ||
398 | cds_ja_for_each_duplicate_safe_rcu(ja_node, tmp_node) { | |
399 | struct cds_ja_range *range; | |
400 | ||
401 | range = caa_container_of(ja_node, | |
402 | struct cds_ja_range, ja_node); | |
403 | ret = cds_ja_del(ja, key, &range->ja_node); | |
404 | if (ret) { | |
405 | goto end; | |
406 | } | |
407 | /* Alone using Judy array, OK to free now */ | |
408 | free_range(range); | |
409 | } | |
410 | } | |
411 | end: | |
412 | return ret; | |
413 | } |