Fix: doc/examples cross-build
[urcu.git] / rculfhash.c
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5e28c532 1/*
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2 * rculfhash.c
3 *
1475579c 4 * Userspace RCU library - Lock-Free Resizable RCU Hash Table
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5 *
6 * Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
0dcf4847 7 * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
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8 *
9 * This library is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * This library is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this library; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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22 */
23
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24/*
25 * Based on the following articles:
26 * - Ori Shalev and Nir Shavit. Split-ordered lists: Lock-free
27 * extensible hash tables. J. ACM 53, 3 (May 2006), 379-405.
28 * - Michael, M. M. High performance dynamic lock-free hash tables
29 * and list-based sets. In Proceedings of the fourteenth annual ACM
30 * symposium on Parallel algorithms and architectures, ACM Press,
31 * (2002), 73-82.
32 *
1475579c 33 * Some specificities of this Lock-Free Resizable RCU Hash Table
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34 * implementation:
35 *
36 * - RCU read-side critical section allows readers to perform hash
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37 * table lookups, as well as traversals, and use the returned objects
38 * safely by allowing memory reclaim to take place only after a grace
39 * period.
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40 * - Add and remove operations are lock-free, and do not need to
41 * allocate memory. They need to be executed within RCU read-side
42 * critical section to ensure the objects they read are valid and to
43 * deal with the cmpxchg ABA problem.
44 * - add and add_unique operations are supported. add_unique checks if
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45 * the node key already exists in the hash table. It ensures not to
46 * populate a duplicate key if the node key already exists in the hash
47 * table.
48 * - The resize operation executes concurrently with
49 * add/add_unique/add_replace/remove/lookup/traversal.
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50 * - Hash table nodes are contained within a split-ordered list. This
51 * list is ordered by incrementing reversed-bits-hash value.
1ee8f000 52 * - An index of bucket nodes is kept. These bucket nodes are the hash
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53 * table "buckets". These buckets are internal nodes that allow to
54 * perform a fast hash lookup, similarly to a skip list. These
55 * buckets are chained together in the split-ordered list, which
56 * allows recursive expansion by inserting new buckets between the
57 * existing buckets. The split-ordered list allows adding new buckets
58 * between existing buckets as the table needs to grow.
59 * - The resize operation for small tables only allows expanding the
60 * hash table. It is triggered automatically by detecting long chains
61 * in the add operation.
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62 * - The resize operation for larger tables (and available through an
63 * API) allows both expanding and shrinking the hash table.
4c42f1b8 64 * - Split-counters are used to keep track of the number of
1475579c 65 * nodes within the hash table for automatic resize triggering.
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66 * - Resize operation initiated by long chain detection is executed by a
67 * call_rcu thread, which keeps lock-freedom of add and remove.
68 * - Resize operations are protected by a mutex.
69 * - The removal operation is split in two parts: first, a "removed"
70 * flag is set in the next pointer within the node to remove. Then,
71 * a "garbage collection" is performed in the bucket containing the
72 * removed node (from the start of the bucket up to the removed node).
73 * All encountered nodes with "removed" flag set in their next
74 * pointers are removed from the linked-list. If the cmpxchg used for
75 * removal fails (due to concurrent garbage-collection or concurrent
76 * add), we retry from the beginning of the bucket. This ensures that
77 * the node with "removed" flag set is removed from the hash table
78 * (not visible to lookups anymore) before the RCU read-side critical
79 * section held across removal ends. Furthermore, this ensures that
80 * the node with "removed" flag set is removed from the linked-list
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81 * before its memory is reclaimed. After setting the "removal" flag,
82 * only the thread which removal is the first to set the "removal
83 * owner" flag (with an xchg) into a node's next pointer is considered
84 * to have succeeded its removal (and thus owns the node to reclaim).
85 * Because we garbage-collect starting from an invariant node (the
86 * start-of-bucket bucket node) up to the "removed" node (or find a
87 * reverse-hash that is higher), we are sure that a successful
88 * traversal of the chain leads to a chain that is present in the
1f67ba50 89 * linked-list (the start node is never removed) and that it does not
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90 * contain the "removed" node anymore, even if concurrent delete/add
91 * operations are changing the structure of the list concurrently.
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92 * - The add operations perform garbage collection of buckets if they
93 * encounter nodes with removed flag set in the bucket where they want
94 * to add their new node. This ensures lock-freedom of add operation by
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95 * helping the remover unlink nodes from the list rather than to wait
96 * for it do to so.
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97 * - There are three memory backends for the hash table buckets: the
98 * "order table", the "chunks", and the "mmap".
99 * - These bucket containers contain a compact version of the hash table
100 * nodes.
101 * - The RCU "order table":
102 * - has a first level table indexed by log2(hash index) which is
103 * copied and expanded by the resize operation. This order table
104 * allows finding the "bucket node" tables.
105 * - There is one bucket node table per hash index order. The size of
106 * each bucket node table is half the number of hashes contained in
107 * this order (except for order 0).
108 * - The RCU "chunks" is best suited for close interaction with a page
109 * allocator. It uses a linear array as index to "chunks" containing
110 * each the same number of buckets.
111 * - The RCU "mmap" memory backend uses a single memory map to hold
112 * all buckets.
5f177b1c 113 * - synchronize_rcu is used to garbage-collect the old bucket node table.
93d46c39 114 *
7f949215 115 * Ordering Guarantees:
0f5543cb 116 *
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117 * To discuss these guarantees, we first define "read" operation as any
118 * of the the basic cds_lfht_lookup, cds_lfht_next_duplicate,
119 * cds_lfht_first, cds_lfht_next operation, as well as
120 * cds_lfht_add_unique (failure).
121 *
122 * We define "read traversal" operation as any of the following
123 * group of operations
0f5543cb 124 * - cds_lfht_lookup followed by iteration with cds_lfht_next_duplicate
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125 * (and/or cds_lfht_next, although less common).
126 * - cds_lfht_add_unique (failure) followed by iteration with
127 * cds_lfht_next_duplicate (and/or cds_lfht_next, although less
128 * common).
129 * - cds_lfht_first followed iteration with cds_lfht_next (and/or
130 * cds_lfht_next_duplicate, although less common).
0f5543cb 131 *
bf09adc7 132 * We define "write" operations as any of cds_lfht_add, cds_lfht_replace,
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133 * cds_lfht_add_unique (success), cds_lfht_add_replace, cds_lfht_del.
134 *
135 * When cds_lfht_add_unique succeeds (returns the node passed as
136 * parameter), it acts as a "write" operation. When cds_lfht_add_unique
137 * fails (returns a node different from the one passed as parameter), it
138 * acts as a "read" operation. A cds_lfht_add_unique failure is a
139 * cds_lfht_lookup "read" operation, therefore, any ordering guarantee
140 * referring to "lookup" imply any of "lookup" or cds_lfht_add_unique
141 * (failure).
142 *
143 * We define "prior" and "later" node as nodes observable by reads and
144 * read traversals respectively before and after a write or sequence of
145 * write operations.
146 *
147 * Hash-table operations are often cascaded, for example, the pointer
148 * returned by a cds_lfht_lookup() might be passed to a cds_lfht_next(),
149 * whose return value might in turn be passed to another hash-table
150 * operation. This entire cascaded series of operations must be enclosed
151 * by a pair of matching rcu_read_lock() and rcu_read_unlock()
152 * operations.
153 *
154 * The following ordering guarantees are offered by this hash table:
155 *
156 * A.1) "read" after "write": if there is ordering between a write and a
157 * later read, then the read is guaranteed to see the write or some
158 * later write.
159 * A.2) "read traversal" after "write": given that there is dependency
160 * ordering between reads in a "read traversal", if there is
161 * ordering between a write and the first read of the traversal,
162 * then the "read traversal" is guaranteed to see the write or
163 * some later write.
164 * B.1) "write" after "read": if there is ordering between a read and a
165 * later write, then the read will never see the write.
166 * B.2) "write" after "read traversal": given that there is dependency
167 * ordering between reads in a "read traversal", if there is
168 * ordering between the last read of the traversal and a later
169 * write, then the "read traversal" will never see the write.
170 * C) "write" while "read traversal": if a write occurs during a "read
171 * traversal", the traversal may, or may not, see the write.
172 * D.1) "write" after "write": if there is ordering between a write and
173 * a later write, then the later write is guaranteed to see the
174 * effects of the first write.
175 * D.2) Concurrent "write" pairs: The system will assign an arbitrary
176 * order to any pair of concurrent conflicting writes.
177 * Non-conflicting writes (for example, to different keys) are
178 * unordered.
179 * E) If a grace period separates a "del" or "replace" operation
180 * and a subsequent operation, then that subsequent operation is
181 * guaranteed not to see the removed item.
182 * F) Uniqueness guarantee: given a hash table that does not contain
183 * duplicate items for a given key, there will only be one item in
184 * the hash table after an arbitrary sequence of add_unique and/or
185 * add_replace operations. Note, however, that a pair of
186 * concurrent read operations might well access two different items
187 * with that key.
188 * G.1) If a pair of lookups for a given key are ordered (e.g. by a
189 * memory barrier), then the second lookup will return the same
190 * node as the previous lookup, or some later node.
191 * G.2) A "read traversal" that starts after the end of a prior "read
192 * traversal" (ordered by memory barriers) is guaranteed to see the
193 * same nodes as the previous traversal, or some later nodes.
194 * G.3) Concurrent "read" pairs: concurrent reads are unordered. For
195 * example, if a pair of reads to the same key run concurrently
196 * with an insertion of that same key, the reads remain unordered
197 * regardless of their return values. In other words, you cannot
198 * rely on the values returned by the reads to deduce ordering.
199 *
200 * Progress guarantees:
201 *
202 * * Reads are wait-free. These operations always move forward in the
203 * hash table linked list, and this list has no loop.
204 * * Writes are lock-free. Any retry loop performed by a write operation
205 * is triggered by progress made within another update operation.
0f5543cb 206 *
1ee8f000 207 * Bucket node tables:
93d46c39 208 *
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209 * hash table hash table the last all bucket node tables
210 * order size bucket node 0 1 2 3 4 5 6(index)
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211 * table size
212 * 0 1 1 1
213 * 1 2 1 1 1
214 * 2 4 2 1 1 2
215 * 3 8 4 1 1 2 4
216 * 4 16 8 1 1 2 4 8
217 * 5 32 16 1 1 2 4 8 16
218 * 6 64 32 1 1 2 4 8 16 32
219 *
1ee8f000 220 * When growing/shrinking, we only focus on the last bucket node table
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221 * which size is (!order ? 1 : (1 << (order -1))).
222 *
223 * Example for growing/shrinking:
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224 * grow hash table from order 5 to 6: init the index=6 bucket node table
225 * shrink hash table from order 6 to 5: fini the index=6 bucket node table
93d46c39 226 *
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227 * A bit of ascii art explanation:
228 *
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229 * The order index is the off-by-one compared to the actual power of 2
230 * because we use index 0 to deal with the 0 special-case.
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231 *
232 * This shows the nodes for a small table ordered by reversed bits:
233 *
234 * bits reverse
235 * 0 000 000
236 * 4 100 001
237 * 2 010 010
238 * 6 110 011
239 * 1 001 100
240 * 5 101 101
241 * 3 011 110
242 * 7 111 111
243 *
244 * This shows the nodes in order of non-reversed bits, linked by
245 * reversed-bit order.
246 *
247 * order bits reverse
248 * 0 0 000 000
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249 * 1 | 1 001 100 <-
250 * 2 | | 2 010 010 <- |
f6fdd688 251 * | | | 3 011 110 | <- |
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252 * 3 -> | | | 4 100 001 | |
253 * -> | | 5 101 101 |
254 * -> | 6 110 011
255 * -> 7 111 111
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256 */
257
2ed95849 258#define _LGPL_SOURCE
125f41db 259#define _GNU_SOURCE
2ed95849 260#include <stdlib.h>
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261#include <errno.h>
262#include <assert.h>
263#include <stdio.h>
abc490a1 264#include <stdint.h>
f000907d 265#include <string.h>
125f41db 266#include <sched.h>
e0ba718a 267
15cfbec7 268#include "config.h"
2ed95849 269#include <urcu.h>
abc490a1 270#include <urcu-call-rcu.h>
7b17c13e 271#include <urcu-flavor.h>
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272#include <urcu/arch.h>
273#include <urcu/uatomic.h>
a42cc659 274#include <urcu/compiler.h>
abc490a1 275#include <urcu/rculfhash.h>
0b6aa001 276#include <rculfhash-internal.h>
5e28c532 277#include <stdio.h>
464a1ec9 278#include <pthread.h>
44395fb7 279
f8994aee 280/*
4c42f1b8 281 * Split-counters lazily update the global counter each 1024
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282 * addition/removal. It automatically keeps track of resize required.
283 * We use the bucket length as indicator for need to expand for small
ffa11a18 284 * tables and machines lacking per-cpu data support.
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285 */
286#define COUNT_COMMIT_ORDER 10
4ddbb355 287#define DEFAULT_SPLIT_COUNT_MASK 0xFUL
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288#define CHAIN_LEN_TARGET 1
289#define CHAIN_LEN_RESIZE_THRESHOLD 3
2ed95849 290
cd95516d 291/*
76a73da8 292 * Define the minimum table size.
cd95516d 293 */
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294#define MIN_TABLE_ORDER 0
295#define MIN_TABLE_SIZE (1UL << MIN_TABLE_ORDER)
cd95516d 296
b7d619b0 297/*
1ee8f000 298 * Minimum number of bucket nodes to touch per thread to parallelize grow/shrink.
b7d619b0 299 */
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300#define MIN_PARTITION_PER_THREAD_ORDER 12
301#define MIN_PARTITION_PER_THREAD (1UL << MIN_PARTITION_PER_THREAD_ORDER)
b7d619b0 302
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303/*
304 * The removed flag needs to be updated atomically with the pointer.
48ed1c18 305 * It indicates that no node must attach to the node scheduled for
b198f0fd 306 * removal, and that node garbage collection must be performed.
1ee8f000 307 * The bucket flag does not require to be updated atomically with the
d95bd160 308 * pointer, but it is added as a pointer low bit flag to save space.
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309 * The "removal owner" flag is used to detect which of the "del"
310 * operation that has set the "removed flag" gets to return the removed
311 * node to its caller. Note that the replace operation does not need to
312 * iteract with the "removal owner" flag, because it validates that
313 * the "removed" flag is not set before performing its cmpxchg.
d95bd160 314 */
d37166c6 315#define REMOVED_FLAG (1UL << 0)
1ee8f000 316#define BUCKET_FLAG (1UL << 1)
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317#define REMOVAL_OWNER_FLAG (1UL << 2)
318#define FLAGS_MASK ((1UL << 3) - 1)
d37166c6 319
bb7b2f26 320/* Value of the end pointer. Should not interact with flags. */
f9c80341 321#define END_VALUE NULL
bb7b2f26 322
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323/*
324 * ht_items_count: Split-counters counting the number of node addition
325 * and removal in the table. Only used if the CDS_LFHT_ACCOUNTING flag
326 * is set at hash table creation.
327 *
328 * These are free-running counters, never reset to zero. They count the
329 * number of add/remove, and trigger every (1 << COUNT_COMMIT_ORDER)
330 * operations to update the global counter. We choose a power-of-2 value
331 * for the trigger to deal with 32 or 64-bit overflow of the counter.
332 */
df44348d 333struct ht_items_count {
860d07e8 334 unsigned long add, del;
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335} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
336
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337/*
338 * rcu_resize_work: Contains arguments passed to RCU worker thread
339 * responsible for performing lazy resize.
340 */
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341struct rcu_resize_work {
342 struct rcu_head head;
14044b37 343 struct cds_lfht *ht;
abc490a1 344};
2ed95849 345
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346/*
347 * partition_resize_work: Contains arguments passed to worker threads
348 * executing the hash table resize on partitions of the hash table
349 * assigned to each processor's worker thread.
350 */
b7d619b0 351struct partition_resize_work {
1af6e26e 352 pthread_t thread_id;
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353 struct cds_lfht *ht;
354 unsigned long i, start, len;
355 void (*fct)(struct cds_lfht *ht, unsigned long i,
356 unsigned long start, unsigned long len);
357};
358
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359/*
360 * Algorithm to reverse bits in a word by lookup table, extended to
361 * 64-bit words.
f9830efd 362 * Source:
abc490a1 363 * http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable
f9830efd 364 * Originally from Public Domain.
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365 */
366
367static const uint8_t BitReverseTable256[256] =
2ed95849 368{
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369#define R2(n) (n), (n) + 2*64, (n) + 1*64, (n) + 3*64
370#define R4(n) R2(n), R2((n) + 2*16), R2((n) + 1*16), R2((n) + 3*16)
371#define R6(n) R4(n), R4((n) + 2*4 ), R4((n) + 1*4 ), R4((n) + 3*4 )
372 R6(0), R6(2), R6(1), R6(3)
373};
374#undef R2
375#undef R4
376#undef R6
2ed95849 377
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378static
379uint8_t bit_reverse_u8(uint8_t v)
380{
381 return BitReverseTable256[v];
382}
ab7d5fc6 383
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384#if (CAA_BITS_PER_LONG == 32)
385static
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386uint32_t bit_reverse_u32(uint32_t v)
387{
388 return ((uint32_t) bit_reverse_u8(v) << 24) |
389 ((uint32_t) bit_reverse_u8(v >> 8) << 16) |
390 ((uint32_t) bit_reverse_u8(v >> 16) << 8) |
391 ((uint32_t) bit_reverse_u8(v >> 24));
2ed95849 392}
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393#else
394static
abc490a1 395uint64_t bit_reverse_u64(uint64_t v)
2ed95849 396{
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397 return ((uint64_t) bit_reverse_u8(v) << 56) |
398 ((uint64_t) bit_reverse_u8(v >> 8) << 48) |
399 ((uint64_t) bit_reverse_u8(v >> 16) << 40) |
400 ((uint64_t) bit_reverse_u8(v >> 24) << 32) |
401 ((uint64_t) bit_reverse_u8(v >> 32) << 24) |
402 ((uint64_t) bit_reverse_u8(v >> 40) << 16) |
403 ((uint64_t) bit_reverse_u8(v >> 48) << 8) |
404 ((uint64_t) bit_reverse_u8(v >> 56));
405}
95bc7fb9 406#endif
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407
408static
409unsigned long bit_reverse_ulong(unsigned long v)
410{
411#if (CAA_BITS_PER_LONG == 32)
412 return bit_reverse_u32(v);
413#else
414 return bit_reverse_u64(v);
415#endif
416}
417
f9830efd 418/*
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419 * fls: returns the position of the most significant bit.
420 * Returns 0 if no bit is set, else returns the position of the most
421 * significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit).
f9830efd 422 */
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423#if defined(__i386) || defined(__x86_64)
424static inline
425unsigned int fls_u32(uint32_t x)
f9830efd 426{
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427 int r;
428
429 asm("bsrl %1,%0\n\t"
430 "jnz 1f\n\t"
431 "movl $-1,%0\n\t"
432 "1:\n\t"
433 : "=r" (r) : "rm" (x));
434 return r + 1;
435}
436#define HAS_FLS_U32
437#endif
438
439#if defined(__x86_64)
440static inline
441unsigned int fls_u64(uint64_t x)
442{
443 long r;
444
445 asm("bsrq %1,%0\n\t"
446 "jnz 1f\n\t"
447 "movq $-1,%0\n\t"
448 "1:\n\t"
449 : "=r" (r) : "rm" (x));
450 return r + 1;
451}
452#define HAS_FLS_U64
453#endif
454
455#ifndef HAS_FLS_U64
456static __attribute__((unused))
457unsigned int fls_u64(uint64_t x)
458{
459 unsigned int r = 64;
460
461 if (!x)
462 return 0;
463
464 if (!(x & 0xFFFFFFFF00000000ULL)) {
465 x <<= 32;
466 r -= 32;
467 }
468 if (!(x & 0xFFFF000000000000ULL)) {
469 x <<= 16;
470 r -= 16;
471 }
472 if (!(x & 0xFF00000000000000ULL)) {
473 x <<= 8;
474 r -= 8;
475 }
476 if (!(x & 0xF000000000000000ULL)) {
477 x <<= 4;
478 r -= 4;
479 }
480 if (!(x & 0xC000000000000000ULL)) {
481 x <<= 2;
482 r -= 2;
483 }
484 if (!(x & 0x8000000000000000ULL)) {
485 x <<= 1;
486 r -= 1;
487 }
488 return r;
489}
490#endif
491
492#ifndef HAS_FLS_U32
493static __attribute__((unused))
494unsigned int fls_u32(uint32_t x)
495{
496 unsigned int r = 32;
f9830efd 497
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498 if (!x)
499 return 0;
500 if (!(x & 0xFFFF0000U)) {
501 x <<= 16;
502 r -= 16;
503 }
504 if (!(x & 0xFF000000U)) {
505 x <<= 8;
506 r -= 8;
507 }
508 if (!(x & 0xF0000000U)) {
509 x <<= 4;
510 r -= 4;
511 }
512 if (!(x & 0xC0000000U)) {
513 x <<= 2;
514 r -= 2;
515 }
516 if (!(x & 0x80000000U)) {
517 x <<= 1;
518 r -= 1;
519 }
520 return r;
521}
522#endif
523
5bc6b66f 524unsigned int cds_lfht_fls_ulong(unsigned long x)
f9830efd 525{
6887cc5e 526#if (CAA_BITS_PER_LONG == 32)
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527 return fls_u32(x);
528#else
529 return fls_u64(x);
530#endif
531}
f9830efd 532
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533/*
534 * Return the minimum order for which x <= (1UL << order).
535 * Return -1 if x is 0.
536 */
5bc6b66f 537int cds_lfht_get_count_order_u32(uint32_t x)
24365af7 538{
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539 if (!x)
540 return -1;
24365af7 541
920f8ef6 542 return fls_u32(x - 1);
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543}
544
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545/*
546 * Return the minimum order for which x <= (1UL << order).
547 * Return -1 if x is 0.
548 */
5bc6b66f 549int cds_lfht_get_count_order_ulong(unsigned long x)
24365af7 550{
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551 if (!x)
552 return -1;
24365af7 553
5bc6b66f 554 return cds_lfht_fls_ulong(x - 1);
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555}
556
557static
ab65b890 558void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth);
f9830efd 559
f8994aee 560static
4105056a 561void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
f8994aee
MD
562 unsigned long count);
563
df44348d 564static long nr_cpus_mask = -1;
4c42f1b8
LJ
565static long split_count_mask = -1;
566
4ddbb355 567#if defined(HAVE_SYSCONF)
4c42f1b8
LJ
568static void ht_init_nr_cpus_mask(void)
569{
570 long maxcpus;
571
572 maxcpus = sysconf(_SC_NPROCESSORS_CONF);
573 if (maxcpus <= 0) {
574 nr_cpus_mask = -2;
575 return;
576 }
577 /*
578 * round up number of CPUs to next power of two, so we
579 * can use & for modulo.
580 */
5bc6b66f 581 maxcpus = 1UL << cds_lfht_get_count_order_ulong(maxcpus);
4c42f1b8
LJ
582 nr_cpus_mask = maxcpus - 1;
583}
4ddbb355
LJ
584#else /* #if defined(HAVE_SYSCONF) */
585static void ht_init_nr_cpus_mask(void)
586{
587 nr_cpus_mask = -2;
588}
589#endif /* #else #if defined(HAVE_SYSCONF) */
df44348d
MD
590
591static
5afadd12 592void alloc_split_items_count(struct cds_lfht *ht)
df44348d 593{
4c42f1b8
LJ
594 if (nr_cpus_mask == -1) {
595 ht_init_nr_cpus_mask();
4ddbb355
LJ
596 if (nr_cpus_mask < 0)
597 split_count_mask = DEFAULT_SPLIT_COUNT_MASK;
598 else
599 split_count_mask = nr_cpus_mask;
df44348d 600 }
4c42f1b8 601
4ddbb355 602 assert(split_count_mask >= 0);
5afadd12
LJ
603
604 if (ht->flags & CDS_LFHT_ACCOUNTING) {
95bc7fb9
MD
605 ht->split_count = calloc(split_count_mask + 1,
606 sizeof(struct ht_items_count));
5afadd12
LJ
607 assert(ht->split_count);
608 } else {
609 ht->split_count = NULL;
610 }
df44348d
MD
611}
612
613static
5afadd12 614void free_split_items_count(struct cds_lfht *ht)
df44348d 615{
5afadd12 616 poison_free(ht->split_count);
df44348d
MD
617}
618
14360f1c 619#if defined(HAVE_SCHED_GETCPU)
df44348d 620static
14360f1c 621int ht_get_split_count_index(unsigned long hash)
df44348d
MD
622{
623 int cpu;
624
4c42f1b8 625 assert(split_count_mask >= 0);
df44348d 626 cpu = sched_getcpu();
8ed51e04 627 if (caa_unlikely(cpu < 0))
14360f1c 628 return hash & split_count_mask;
df44348d 629 else
4c42f1b8 630 return cpu & split_count_mask;
df44348d 631}
14360f1c
LJ
632#else /* #if defined(HAVE_SCHED_GETCPU) */
633static
634int ht_get_split_count_index(unsigned long hash)
635{
636 return hash & split_count_mask;
637}
638#endif /* #else #if defined(HAVE_SCHED_GETCPU) */
df44348d
MD
639
640static
14360f1c 641void ht_count_add(struct cds_lfht *ht, unsigned long size, unsigned long hash)
df44348d 642{
4c42f1b8
LJ
643 unsigned long split_count;
644 int index;
314558bf 645 long count;
df44348d 646
8ed51e04 647 if (caa_unlikely(!ht->split_count))
3171717f 648 return;
14360f1c 649 index = ht_get_split_count_index(hash);
4c42f1b8 650 split_count = uatomic_add_return(&ht->split_count[index].add, 1);
314558bf
MD
651 if (caa_likely(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))
652 return;
653 /* Only if number of add multiple of 1UL << COUNT_COMMIT_ORDER */
654
655 dbg_printf("add split count %lu\n", split_count);
656 count = uatomic_add_return(&ht->count,
657 1UL << COUNT_COMMIT_ORDER);
4c299dcb 658 if (caa_likely(count & (count - 1)))
314558bf
MD
659 return;
660 /* Only if global count is power of 2 */
661
662 if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) < size)
663 return;
664 dbg_printf("add set global %ld\n", count);
665 cds_lfht_resize_lazy_count(ht, size,
666 count >> (CHAIN_LEN_TARGET - 1));
df44348d
MD
667}
668
669static
14360f1c 670void ht_count_del(struct cds_lfht *ht, unsigned long size, unsigned long hash)
df44348d 671{
4c42f1b8
LJ
672 unsigned long split_count;
673 int index;
314558bf 674 long count;
df44348d 675
8ed51e04 676 if (caa_unlikely(!ht->split_count))
3171717f 677 return;
14360f1c 678 index = ht_get_split_count_index(hash);
4c42f1b8 679 split_count = uatomic_add_return(&ht->split_count[index].del, 1);
314558bf
MD
680 if (caa_likely(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))
681 return;
682 /* Only if number of deletes multiple of 1UL << COUNT_COMMIT_ORDER */
683
684 dbg_printf("del split count %lu\n", split_count);
685 count = uatomic_add_return(&ht->count,
686 -(1UL << COUNT_COMMIT_ORDER));
4c299dcb 687 if (caa_likely(count & (count - 1)))
314558bf
MD
688 return;
689 /* Only if global count is power of 2 */
690
691 if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) >= size)
692 return;
693 dbg_printf("del set global %ld\n", count);
694 /*
695 * Don't shrink table if the number of nodes is below a
696 * certain threshold.
697 */
698 if (count < (1UL << COUNT_COMMIT_ORDER) * (split_count_mask + 1))
699 return;
700 cds_lfht_resize_lazy_count(ht, size,
701 count >> (CHAIN_LEN_TARGET - 1));
df44348d
MD
702}
703
f9830efd 704static
4105056a 705void check_resize(struct cds_lfht *ht, unsigned long size, uint32_t chain_len)
f9830efd 706{
f8994aee
MD
707 unsigned long count;
708
b8af5011
MD
709 if (!(ht->flags & CDS_LFHT_AUTO_RESIZE))
710 return;
f8994aee
MD
711 count = uatomic_read(&ht->count);
712 /*
713 * Use bucket-local length for small table expand and for
714 * environments lacking per-cpu data support.
715 */
716 if (count >= (1UL << COUNT_COMMIT_ORDER))
717 return;
24365af7 718 if (chain_len > 100)
f0c29ed7 719 dbg_printf("WARNING: large chain length: %u.\n",
24365af7 720 chain_len);
3390d470 721 if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD)
ab65b890 722 cds_lfht_resize_lazy_grow(ht, size,
5bc6b66f 723 cds_lfht_get_count_order_u32(chain_len - (CHAIN_LEN_TARGET - 1)));
f9830efd
MD
724}
725
abc490a1 726static
14044b37 727struct cds_lfht_node *clear_flag(struct cds_lfht_node *node)
abc490a1 728{
14044b37 729 return (struct cds_lfht_node *) (((unsigned long) node) & ~FLAGS_MASK);
abc490a1
MD
730}
731
732static
14044b37 733int is_removed(struct cds_lfht_node *node)
abc490a1 734{
d37166c6 735 return ((unsigned long) node) & REMOVED_FLAG;
abc490a1
MD
736}
737
f5596c94 738static
1ee8f000 739int is_bucket(struct cds_lfht_node *node)
f5596c94 740{
1ee8f000 741 return ((unsigned long) node) & BUCKET_FLAG;
f5596c94
MD
742}
743
744static
1ee8f000 745struct cds_lfht_node *flag_bucket(struct cds_lfht_node *node)
f5596c94 746{
1ee8f000 747 return (struct cds_lfht_node *) (((unsigned long) node) | BUCKET_FLAG);
f5596c94 748}
bb7b2f26 749
db00ccc3
MD
750static
751int is_removal_owner(struct cds_lfht_node *node)
752{
753 return ((unsigned long) node) & REMOVAL_OWNER_FLAG;
754}
755
756static
757struct cds_lfht_node *flag_removal_owner(struct cds_lfht_node *node)
758{
759 return (struct cds_lfht_node *) (((unsigned long) node) | REMOVAL_OWNER_FLAG);
760}
761
71bb3aca
MD
762static
763struct cds_lfht_node *flag_removed_or_removal_owner(struct cds_lfht_node *node)
764{
765 return (struct cds_lfht_node *) (((unsigned long) node) | REMOVED_FLAG | REMOVAL_OWNER_FLAG);
766}
767
bb7b2f26
MD
768static
769struct cds_lfht_node *get_end(void)
770{
771 return (struct cds_lfht_node *) END_VALUE;
772}
773
774static
775int is_end(struct cds_lfht_node *node)
776{
777 return clear_flag(node) == (struct cds_lfht_node *) END_VALUE;
778}
779
abc490a1 780static
ab65b890
LJ
781unsigned long _uatomic_xchg_monotonic_increase(unsigned long *ptr,
782 unsigned long v)
abc490a1
MD
783{
784 unsigned long old1, old2;
785
786 old1 = uatomic_read(ptr);
787 do {
788 old2 = old1;
789 if (old2 >= v)
f9830efd 790 return old2;
abc490a1 791 } while ((old1 = uatomic_cmpxchg(ptr, old2, v)) != old2);
ab65b890 792 return old2;
abc490a1
MD
793}
794
48f1b16d
LJ
795static
796void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order)
797{
0b6aa001 798 return ht->mm->alloc_bucket_table(ht, order);
48f1b16d
LJ
799}
800
801/*
802 * cds_lfht_free_bucket_table() should be called with decreasing order.
803 * When cds_lfht_free_bucket_table(0) is called, it means the whole
804 * lfht is destroyed.
805 */
806static
807void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order)
808{
0b6aa001 809 return ht->mm->free_bucket_table(ht, order);
48f1b16d
LJ
810}
811
9d72a73f
LJ
812static inline
813struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index)
f4a9cc0b 814{
0b6aa001 815 return ht->bucket_at(ht, index);
f4a9cc0b
LJ
816}
817
9d72a73f
LJ
818static inline
819struct cds_lfht_node *lookup_bucket(struct cds_lfht *ht, unsigned long size,
820 unsigned long hash)
821{
822 assert(size > 0);
823 return bucket_at(ht, hash & (size - 1));
824}
825
273399de
MD
826/*
827 * Remove all logically deleted nodes from a bucket up to a certain node key.
828 */
829static
1ee8f000 830void _cds_lfht_gc_bucket(struct cds_lfht_node *bucket, struct cds_lfht_node *node)
273399de 831{
14044b37 832 struct cds_lfht_node *iter_prev, *iter, *next, *new_next;
273399de 833
1ee8f000
LJ
834 assert(!is_bucket(bucket));
835 assert(!is_removed(bucket));
2f943cd7 836 assert(!is_removal_owner(bucket));
1ee8f000 837 assert(!is_bucket(node));
c90201ac 838 assert(!is_removed(node));
2f943cd7 839 assert(!is_removal_owner(node));
273399de 840 for (;;) {
1ee8f000
LJ
841 iter_prev = bucket;
842 /* We can always skip the bucket node initially */
04db56f8 843 iter = rcu_dereference(iter_prev->next);
b4cb483f 844 assert(!is_removed(iter));
2f943cd7 845 assert(!is_removal_owner(iter));
04db56f8 846 assert(iter_prev->reverse_hash <= node->reverse_hash);
bd4db153 847 /*
1ee8f000 848 * We should never be called with bucket (start of chain)
bd4db153
MD
849 * and logically removed node (end of path compression
850 * marker) being the actual same node. This would be a
851 * bug in the algorithm implementation.
852 */
1ee8f000 853 assert(bucket != node);
273399de 854 for (;;) {
8ed51e04 855 if (caa_unlikely(is_end(iter)))
f9c80341 856 return;
04db56f8 857 if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash))
f9c80341 858 return;
04db56f8 859 next = rcu_dereference(clear_flag(iter)->next);
8ed51e04 860 if (caa_likely(is_removed(next)))
273399de 861 break;
b453eae1 862 iter_prev = clear_flag(iter);
273399de
MD
863 iter = next;
864 }
b198f0fd 865 assert(!is_removed(iter));
2f943cd7 866 assert(!is_removal_owner(iter));
1ee8f000
LJ
867 if (is_bucket(iter))
868 new_next = flag_bucket(clear_flag(next));
f5596c94
MD
869 else
870 new_next = clear_flag(next);
04db56f8 871 (void) uatomic_cmpxchg(&iter_prev->next, iter, new_next);
273399de
MD
872 }
873}
874
9357c415
MD
875static
876int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
877 struct cds_lfht_node *old_node,
3fb86f26 878 struct cds_lfht_node *old_next,
9357c415
MD
879 struct cds_lfht_node *new_node)
880{
04db56f8 881 struct cds_lfht_node *bucket, *ret_next;
9357c415
MD
882
883 if (!old_node) /* Return -ENOENT if asked to replace NULL node */
7801dadd 884 return -ENOENT;
9357c415
MD
885
886 assert(!is_removed(old_node));
2f943cd7 887 assert(!is_removal_owner(old_node));
1ee8f000 888 assert(!is_bucket(old_node));
9357c415 889 assert(!is_removed(new_node));
2f943cd7 890 assert(!is_removal_owner(new_node));
1ee8f000 891 assert(!is_bucket(new_node));
9357c415 892 assert(new_node != old_node);
3fb86f26 893 for (;;) {
9357c415 894 /* Insert after node to be replaced */
9357c415
MD
895 if (is_removed(old_next)) {
896 /*
897 * Too late, the old node has been removed under us
898 * between lookup and replace. Fail.
899 */
7801dadd 900 return -ENOENT;
9357c415 901 }
feda2722
LJ
902 assert(old_next == clear_flag(old_next));
903 assert(new_node != old_next);
71bb3aca
MD
904 /*
905 * REMOVAL_OWNER flag is _NEVER_ set before the REMOVED
906 * flag. It is either set atomically at the same time
907 * (replace) or after (del).
908 */
909 assert(!is_removal_owner(old_next));
feda2722 910 new_node->next = old_next;
9357c415
MD
911 /*
912 * Here is the whole trick for lock-free replace: we add
913 * the replacement node _after_ the node we want to
914 * replace by atomically setting its next pointer at the
915 * same time we set its removal flag. Given that
916 * the lookups/get next use an iterator aware of the
917 * next pointer, they will either skip the old node due
918 * to the removal flag and see the new node, or use
919 * the old node, but will not see the new one.
db00ccc3
MD
920 * This is a replacement of a node with another node
921 * that has the same value: we are therefore not
71bb3aca
MD
922 * removing a value from the hash table. We set both the
923 * REMOVED and REMOVAL_OWNER flags atomically so we own
924 * the node after successful cmpxchg.
9357c415 925 */
04db56f8 926 ret_next = uatomic_cmpxchg(&old_node->next,
71bb3aca 927 old_next, flag_removed_or_removal_owner(new_node));
3fb86f26 928 if (ret_next == old_next)
7801dadd 929 break; /* We performed the replacement. */
3fb86f26
LJ
930 old_next = ret_next;
931 }
9357c415 932
9357c415
MD
933 /*
934 * Ensure that the old node is not visible to readers anymore:
935 * lookup for the node, and remove it (along with any other
936 * logically removed node) if found.
937 */
04db56f8
LJ
938 bucket = lookup_bucket(ht, size, bit_reverse_ulong(old_node->reverse_hash));
939 _cds_lfht_gc_bucket(bucket, new_node);
7801dadd 940
a85eff52 941 assert(is_removed(CMM_LOAD_SHARED(old_node->next)));
7801dadd 942 return 0;
9357c415
MD
943}
944
83beee94
MD
945/*
946 * A non-NULL unique_ret pointer uses the "add unique" (or uniquify) add
947 * mode. A NULL unique_ret allows creation of duplicate keys.
948 */
abc490a1 949static
83beee94 950void _cds_lfht_add(struct cds_lfht *ht,
91a75cc5 951 unsigned long hash,
0422d92c 952 cds_lfht_match_fct match,
996ff57c 953 const void *key,
83beee94
MD
954 unsigned long size,
955 struct cds_lfht_node *node,
956 struct cds_lfht_iter *unique_ret,
1ee8f000 957 int bucket_flag)
abc490a1 958{
14044b37 959 struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next,
960c9e4f 960 *return_node;
04db56f8 961 struct cds_lfht_node *bucket;
abc490a1 962
1ee8f000 963 assert(!is_bucket(node));
c90201ac 964 assert(!is_removed(node));
2f943cd7 965 assert(!is_removal_owner(node));
91a75cc5 966 bucket = lookup_bucket(ht, size, hash);
abc490a1 967 for (;;) {
adc0de68 968 uint32_t chain_len = 0;
abc490a1 969
11519af6
MD
970 /*
971 * iter_prev points to the non-removed node prior to the
972 * insert location.
11519af6 973 */
04db56f8 974 iter_prev = bucket;
1ee8f000 975 /* We can always skip the bucket node initially */
04db56f8
LJ
976 iter = rcu_dereference(iter_prev->next);
977 assert(iter_prev->reverse_hash <= node->reverse_hash);
abc490a1 978 for (;;) {
8ed51e04 979 if (caa_unlikely(is_end(iter)))
273399de 980 goto insert;
04db56f8 981 if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash))
273399de 982 goto insert;
238cc06e 983
1ee8f000
LJ
984 /* bucket node is the first node of the identical-hash-value chain */
985 if (bucket_flag && clear_flag(iter)->reverse_hash == node->reverse_hash)
194fdbd1 986 goto insert;
238cc06e 987
04db56f8 988 next = rcu_dereference(clear_flag(iter)->next);
8ed51e04 989 if (caa_unlikely(is_removed(next)))
9dba85be 990 goto gc_node;
238cc06e
LJ
991
992 /* uniquely add */
83beee94 993 if (unique_ret
1ee8f000 994 && !is_bucket(next)
04db56f8 995 && clear_flag(iter)->reverse_hash == node->reverse_hash) {
238cc06e
LJ
996 struct cds_lfht_iter d_iter = { .node = node, .next = iter, };
997
998 /*
999 * uniquely adding inserts the node as the first
1000 * node of the identical-hash-value node chain.
1001 *
1002 * This semantic ensures no duplicated keys
1003 * should ever be observable in the table
1f67ba50
MD
1004 * (including traversing the table node by
1005 * node by forward iterations)
238cc06e 1006 */
04db56f8 1007 cds_lfht_next_duplicate(ht, match, key, &d_iter);
238cc06e
LJ
1008 if (!d_iter.node)
1009 goto insert;
1010
1011 *unique_ret = d_iter;
83beee94 1012 return;
48ed1c18 1013 }
238cc06e 1014
11519af6 1015 /* Only account for identical reverse hash once */
04db56f8 1016 if (iter_prev->reverse_hash != clear_flag(iter)->reverse_hash
1ee8f000 1017 && !is_bucket(next))
4105056a 1018 check_resize(ht, size, ++chain_len);
11519af6 1019 iter_prev = clear_flag(iter);
273399de 1020 iter = next;
abc490a1 1021 }
48ed1c18 1022
273399de 1023 insert:
7ec59d3b 1024 assert(node != clear_flag(iter));
11519af6 1025 assert(!is_removed(iter_prev));
2f943cd7 1026 assert(!is_removal_owner(iter_prev));
c90201ac 1027 assert(!is_removed(iter));
2f943cd7 1028 assert(!is_removal_owner(iter));
f000907d 1029 assert(iter_prev != node);
1ee8f000 1030 if (!bucket_flag)
04db56f8 1031 node->next = clear_flag(iter);
f9c80341 1032 else
1ee8f000
LJ
1033 node->next = flag_bucket(clear_flag(iter));
1034 if (is_bucket(iter))
1035 new_node = flag_bucket(node);
f5596c94
MD
1036 else
1037 new_node = node;
04db56f8 1038 if (uatomic_cmpxchg(&iter_prev->next, iter,
48ed1c18 1039 new_node) != iter) {
273399de 1040 continue; /* retry */
48ed1c18 1041 } else {
83beee94 1042 return_node = node;
960c9e4f 1043 goto end;
48ed1c18
MD
1044 }
1045
9dba85be
MD
1046 gc_node:
1047 assert(!is_removed(iter));
2f943cd7 1048 assert(!is_removal_owner(iter));
1ee8f000
LJ
1049 if (is_bucket(iter))
1050 new_next = flag_bucket(clear_flag(next));
f5596c94
MD
1051 else
1052 new_next = clear_flag(next);
04db56f8 1053 (void) uatomic_cmpxchg(&iter_prev->next, iter, new_next);
273399de 1054 /* retry */
464a1ec9 1055 }
9357c415 1056end:
83beee94
MD
1057 if (unique_ret) {
1058 unique_ret->node = return_node;
1059 /* unique_ret->next left unset, never used. */
1060 }
abc490a1 1061}
464a1ec9 1062
abc490a1 1063static
860d07e8 1064int _cds_lfht_del(struct cds_lfht *ht, unsigned long size,
b65ec430 1065 struct cds_lfht_node *node)
abc490a1 1066{
db00ccc3 1067 struct cds_lfht_node *bucket, *next;
5e28c532 1068
9357c415 1069 if (!node) /* Return -ENOENT if asked to delete NULL node */
743f9143 1070 return -ENOENT;
9357c415 1071
7ec59d3b 1072 /* logically delete the node */
1ee8f000 1073 assert(!is_bucket(node));
c90201ac 1074 assert(!is_removed(node));
db00ccc3 1075 assert(!is_removal_owner(node));
48ed1c18 1076
db00ccc3
MD
1077 /*
1078 * We are first checking if the node had previously been
1079 * logically removed (this check is not atomic with setting the
1080 * logical removal flag). Return -ENOENT if the node had
1081 * previously been removed.
1082 */
a85eff52 1083 next = CMM_LOAD_SHARED(node->next); /* next is not dereferenced */
db00ccc3
MD
1084 if (caa_unlikely(is_removed(next)))
1085 return -ENOENT;
b65ec430 1086 assert(!is_bucket(next));
196f4fab
MD
1087 /*
1088 * The del operation semantic guarantees a full memory barrier
1089 * before the uatomic_or atomic commit of the deletion flag.
1090 */
1091 cmm_smp_mb__before_uatomic_or();
db00ccc3
MD
1092 /*
1093 * We set the REMOVED_FLAG unconditionally. Note that there may
1094 * be more than one concurrent thread setting this flag.
1095 * Knowing which wins the race will be known after the garbage
1096 * collection phase, stay tuned!
1097 */
1098 uatomic_or(&node->next, REMOVED_FLAG);
7ec59d3b 1099 /* We performed the (logical) deletion. */
7ec59d3b
MD
1100
1101 /*
1102 * Ensure that the node is not visible to readers anymore: lookup for
273399de
MD
1103 * the node, and remove it (along with any other logically removed node)
1104 * if found.
11519af6 1105 */
04db56f8
LJ
1106 bucket = lookup_bucket(ht, size, bit_reverse_ulong(node->reverse_hash));
1107 _cds_lfht_gc_bucket(bucket, node);
743f9143 1108
a85eff52 1109 assert(is_removed(CMM_LOAD_SHARED(node->next)));
db00ccc3
MD
1110 /*
1111 * Last phase: atomically exchange node->next with a version
1112 * having "REMOVAL_OWNER_FLAG" set. If the returned node->next
1113 * pointer did _not_ have "REMOVAL_OWNER_FLAG" set, we now own
1114 * the node and win the removal race.
1115 * It is interesting to note that all "add" paths are forbidden
1116 * to change the next pointer starting from the point where the
1117 * REMOVED_FLAG is set, so here using a read, followed by a
1118 * xchg() suffice to guarantee that the xchg() will ever only
1119 * set the "REMOVAL_OWNER_FLAG" (or change nothing if the flag
1120 * was already set).
1121 */
1122 if (!is_removal_owner(uatomic_xchg(&node->next,
1123 flag_removal_owner(node->next))))
1124 return 0;
1125 else
1126 return -ENOENT;
abc490a1 1127}
2ed95849 1128
b7d619b0
MD
1129static
1130void *partition_resize_thread(void *arg)
1131{
1132 struct partition_resize_work *work = arg;
1133
7b17c13e 1134 work->ht->flavor->register_thread();
b7d619b0 1135 work->fct(work->ht, work->i, work->start, work->len);
7b17c13e 1136 work->ht->flavor->unregister_thread();
b7d619b0
MD
1137 return NULL;
1138}
1139
1140static
1141void partition_resize_helper(struct cds_lfht *ht, unsigned long i,
1142 unsigned long len,
1143 void (*fct)(struct cds_lfht *ht, unsigned long i,
1144 unsigned long start, unsigned long len))
1145{
1146 unsigned long partition_len;
1147 struct partition_resize_work *work;
6083a889
MD
1148 int thread, ret;
1149 unsigned long nr_threads;
b7d619b0 1150
6083a889
MD
1151 /*
1152 * Note: nr_cpus_mask + 1 is always power of 2.
1153 * We spawn just the number of threads we need to satisfy the minimum
1154 * partition size, up to the number of CPUs in the system.
1155 */
91452a6a
MD
1156 if (nr_cpus_mask > 0) {
1157 nr_threads = min(nr_cpus_mask + 1,
1158 len >> MIN_PARTITION_PER_THREAD_ORDER);
1159 } else {
1160 nr_threads = 1;
1161 }
5bc6b66f 1162 partition_len = len >> cds_lfht_get_count_order_ulong(nr_threads);
6083a889 1163 work = calloc(nr_threads, sizeof(*work));
b7d619b0 1164 assert(work);
6083a889
MD
1165 for (thread = 0; thread < nr_threads; thread++) {
1166 work[thread].ht = ht;
1167 work[thread].i = i;
1168 work[thread].len = partition_len;
1169 work[thread].start = thread * partition_len;
1170 work[thread].fct = fct;
1af6e26e 1171 ret = pthread_create(&(work[thread].thread_id), ht->resize_attr,
6083a889 1172 partition_resize_thread, &work[thread]);
b7d619b0
MD
1173 assert(!ret);
1174 }
6083a889 1175 for (thread = 0; thread < nr_threads; thread++) {
1af6e26e 1176 ret = pthread_join(work[thread].thread_id, NULL);
b7d619b0
MD
1177 assert(!ret);
1178 }
1179 free(work);
b7d619b0
MD
1180}
1181
e8de508e
MD
1182/*
1183 * Holding RCU read lock to protect _cds_lfht_add against memory
1184 * reclaim that could be performed by other call_rcu worker threads (ABA
1185 * problem).
9ee0fc9a 1186 *
b7d619b0 1187 * When we reach a certain length, we can split this population phase over
9ee0fc9a
MD
1188 * many worker threads, based on the number of CPUs available in the system.
1189 * This should therefore take care of not having the expand lagging behind too
1190 * many concurrent insertion threads by using the scheduler's ability to
1ee8f000 1191 * schedule bucket node population fairly with insertions.
e8de508e 1192 */
4105056a 1193static
b7d619b0
MD
1194void init_table_populate_partition(struct cds_lfht *ht, unsigned long i,
1195 unsigned long start, unsigned long len)
4105056a 1196{
9d72a73f 1197 unsigned long j, size = 1UL << (i - 1);
4105056a 1198
d0d8f9aa 1199 assert(i > MIN_TABLE_ORDER);
7b17c13e 1200 ht->flavor->read_lock();
9d72a73f
LJ
1201 for (j = size + start; j < size + start + len; j++) {
1202 struct cds_lfht_node *new_node = bucket_at(ht, j);
1203
1204 assert(j >= size && j < (size << 1));
1205 dbg_printf("init populate: order %lu index %lu hash %lu\n",
1206 i, j, j);
1207 new_node->reverse_hash = bit_reverse_ulong(j);
91a75cc5 1208 _cds_lfht_add(ht, j, NULL, NULL, size, new_node, NULL, 1);
4105056a 1209 }
7b17c13e 1210 ht->flavor->read_unlock();
b7d619b0
MD
1211}
1212
1213static
1214void init_table_populate(struct cds_lfht *ht, unsigned long i,
1215 unsigned long len)
1216{
1217 assert(nr_cpus_mask != -1);
6083a889 1218 if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) {
7b17c13e 1219 ht->flavor->thread_online();
b7d619b0 1220 init_table_populate_partition(ht, i, 0, len);
7b17c13e 1221 ht->flavor->thread_offline();
b7d619b0
MD
1222 return;
1223 }
1224 partition_resize_helper(ht, i, len, init_table_populate_partition);
4105056a
MD
1225}
1226
abc490a1 1227static
4105056a 1228void init_table(struct cds_lfht *ht,
93d46c39 1229 unsigned long first_order, unsigned long last_order)
24365af7 1230{
93d46c39 1231 unsigned long i;
24365af7 1232
93d46c39
LJ
1233 dbg_printf("init table: first_order %lu last_order %lu\n",
1234 first_order, last_order);
d0d8f9aa 1235 assert(first_order > MIN_TABLE_ORDER);
93d46c39 1236 for (i = first_order; i <= last_order; i++) {
4105056a 1237 unsigned long len;
24365af7 1238
4f6e90b7 1239 len = 1UL << (i - 1);
f0c29ed7 1240 dbg_printf("init order %lu len: %lu\n", i, len);
4d676753
MD
1241
1242 /* Stop expand if the resize target changes under us */
7b3893e4 1243 if (CMM_LOAD_SHARED(ht->resize_target) < (1UL << i))
4d676753
MD
1244 break;
1245
48f1b16d 1246 cds_lfht_alloc_bucket_table(ht, i);
4105056a 1247
4105056a 1248 /*
1ee8f000
LJ
1249 * Set all bucket nodes reverse hash values for a level and
1250 * link all bucket nodes into the table.
4105056a 1251 */
dc1da8f6 1252 init_table_populate(ht, i, len);
4105056a 1253
f9c80341
MD
1254 /*
1255 * Update table size.
1256 */
1257 cmm_smp_wmb(); /* populate data before RCU size */
7b3893e4 1258 CMM_STORE_SHARED(ht->size, 1UL << i);
f9c80341 1259
4f6e90b7 1260 dbg_printf("init new size: %lu\n", 1UL << i);
4105056a
MD
1261 if (CMM_LOAD_SHARED(ht->in_progress_destroy))
1262 break;
1263 }
1264}
1265
e8de508e
MD
1266/*
1267 * Holding RCU read lock to protect _cds_lfht_remove against memory
1268 * reclaim that could be performed by other call_rcu worker threads (ABA
1269 * problem).
1270 * For a single level, we logically remove and garbage collect each node.
1271 *
1272 * As a design choice, we perform logical removal and garbage collection on a
1273 * node-per-node basis to simplify this algorithm. We also assume keeping good
1274 * cache locality of the operation would overweight possible performance gain
1275 * that could be achieved by batching garbage collection for multiple levels.
1276 * However, this would have to be justified by benchmarks.
1277 *
1278 * Concurrent removal and add operations are helping us perform garbage
1279 * collection of logically removed nodes. We guarantee that all logically
1280 * removed nodes have been garbage-collected (unlinked) before call_rcu is
1ee8f000 1281 * invoked to free a hole level of bucket nodes (after a grace period).
e8de508e 1282 *
1f67ba50
MD
1283 * Logical removal and garbage collection can therefore be done in batch
1284 * or on a node-per-node basis, as long as the guarantee above holds.
9ee0fc9a 1285 *
b7d619b0
MD
1286 * When we reach a certain length, we can split this removal over many worker
1287 * threads, based on the number of CPUs available in the system. This should
1288 * take care of not letting resize process lag behind too many concurrent
9ee0fc9a 1289 * updater threads actively inserting into the hash table.
e8de508e 1290 */
4105056a 1291static
b7d619b0
MD
1292void remove_table_partition(struct cds_lfht *ht, unsigned long i,
1293 unsigned long start, unsigned long len)
4105056a 1294{
9d72a73f 1295 unsigned long j, size = 1UL << (i - 1);
4105056a 1296
d0d8f9aa 1297 assert(i > MIN_TABLE_ORDER);
7b17c13e 1298 ht->flavor->read_lock();
9d72a73f 1299 for (j = size + start; j < size + start + len; j++) {
2e2ce1e9
LJ
1300 struct cds_lfht_node *fini_bucket = bucket_at(ht, j);
1301 struct cds_lfht_node *parent_bucket = bucket_at(ht, j - size);
9d72a73f
LJ
1302
1303 assert(j >= size && j < (size << 1));
1304 dbg_printf("remove entry: order %lu index %lu hash %lu\n",
1305 i, j, j);
2e2ce1e9
LJ
1306 /* Set the REMOVED_FLAG to freeze the ->next for gc */
1307 uatomic_or(&fini_bucket->next, REMOVED_FLAG);
1308 _cds_lfht_gc_bucket(parent_bucket, fini_bucket);
abc490a1 1309 }
7b17c13e 1310 ht->flavor->read_unlock();
b7d619b0
MD
1311}
1312
1313static
1314void remove_table(struct cds_lfht *ht, unsigned long i, unsigned long len)
1315{
1316
1317 assert(nr_cpus_mask != -1);
6083a889 1318 if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) {
7b17c13e 1319 ht->flavor->thread_online();
b7d619b0 1320 remove_table_partition(ht, i, 0, len);
7b17c13e 1321 ht->flavor->thread_offline();
b7d619b0
MD
1322 return;
1323 }
1324 partition_resize_helper(ht, i, len, remove_table_partition);
2ed95849
MD
1325}
1326
61adb337
MD
1327/*
1328 * fini_table() is never called for first_order == 0, which is why
1329 * free_by_rcu_order == 0 can be used as criterion to know if free must
1330 * be called.
1331 */
1475579c 1332static
4105056a 1333void fini_table(struct cds_lfht *ht,
93d46c39 1334 unsigned long first_order, unsigned long last_order)
1475579c 1335{
93d46c39 1336 long i;
48f1b16d 1337 unsigned long free_by_rcu_order = 0;
1475579c 1338
93d46c39
LJ
1339 dbg_printf("fini table: first_order %lu last_order %lu\n",
1340 first_order, last_order);
d0d8f9aa 1341 assert(first_order > MIN_TABLE_ORDER);
93d46c39 1342 for (i = last_order; i >= first_order; i--) {
4105056a 1343 unsigned long len;
1475579c 1344
4f6e90b7 1345 len = 1UL << (i - 1);
1475579c 1346 dbg_printf("fini order %lu len: %lu\n", i, len);
4105056a 1347
4d676753 1348 /* Stop shrink if the resize target changes under us */
7b3893e4 1349 if (CMM_LOAD_SHARED(ht->resize_target) > (1UL << (i - 1)))
4d676753
MD
1350 break;
1351
1352 cmm_smp_wmb(); /* populate data before RCU size */
7b3893e4 1353 CMM_STORE_SHARED(ht->size, 1UL << (i - 1));
4d676753
MD
1354
1355 /*
1356 * We need to wait for all add operations to reach Q.S. (and
1357 * thus use the new table for lookups) before we can start
1ee8f000 1358 * releasing the old bucket nodes. Otherwise their lookup will
4d676753
MD
1359 * return a logically removed node as insert position.
1360 */
7b17c13e 1361 ht->flavor->update_synchronize_rcu();
48f1b16d
LJ
1362 if (free_by_rcu_order)
1363 cds_lfht_free_bucket_table(ht, free_by_rcu_order);
4d676753 1364
21263e21 1365 /*
1ee8f000
LJ
1366 * Set "removed" flag in bucket nodes about to be removed.
1367 * Unlink all now-logically-removed bucket node pointers.
4105056a
MD
1368 * Concurrent add/remove operation are helping us doing
1369 * the gc.
21263e21 1370 */
4105056a
MD
1371 remove_table(ht, i, len);
1372
48f1b16d 1373 free_by_rcu_order = i;
4105056a
MD
1374
1375 dbg_printf("fini new size: %lu\n", 1UL << i);
1475579c
MD
1376 if (CMM_LOAD_SHARED(ht->in_progress_destroy))
1377 break;
1378 }
0d14ceb2 1379
48f1b16d 1380 if (free_by_rcu_order) {
7b17c13e 1381 ht->flavor->update_synchronize_rcu();
48f1b16d 1382 cds_lfht_free_bucket_table(ht, free_by_rcu_order);
0d14ceb2 1383 }
1475579c
MD
1384}
1385
ff0d69de 1386static
1ee8f000 1387void cds_lfht_create_bucket(struct cds_lfht *ht, unsigned long size)
ff0d69de 1388{
04db56f8 1389 struct cds_lfht_node *prev, *node;
9d72a73f 1390 unsigned long order, len, i;
ff0d69de 1391
48f1b16d 1392 cds_lfht_alloc_bucket_table(ht, 0);
ff0d69de 1393
9d72a73f
LJ
1394 dbg_printf("create bucket: order 0 index 0 hash 0\n");
1395 node = bucket_at(ht, 0);
1396 node->next = flag_bucket(get_end());
1397 node->reverse_hash = 0;
ff0d69de 1398
5bc6b66f 1399 for (order = 1; order < cds_lfht_get_count_order_ulong(size) + 1; order++) {
ff0d69de 1400 len = 1UL << (order - 1);
48f1b16d 1401 cds_lfht_alloc_bucket_table(ht, order);
ff0d69de 1402
9d72a73f
LJ
1403 for (i = 0; i < len; i++) {
1404 /*
1405 * Now, we are trying to init the node with the
1406 * hash=(len+i) (which is also a bucket with the
1407 * index=(len+i)) and insert it into the hash table,
1408 * so this node has to be inserted after the bucket
1409 * with the index=(len+i)&(len-1)=i. And because there
1410 * is no other non-bucket node nor bucket node with
1411 * larger index/hash inserted, so the bucket node
1412 * being inserted should be inserted directly linked
1413 * after the bucket node with index=i.
1414 */
1415 prev = bucket_at(ht, i);
1416 node = bucket_at(ht, len + i);
ff0d69de 1417
1ee8f000 1418 dbg_printf("create bucket: order %lu index %lu hash %lu\n",
9d72a73f
LJ
1419 order, len + i, len + i);
1420 node->reverse_hash = bit_reverse_ulong(len + i);
1421
1422 /* insert after prev */
1423 assert(is_bucket(prev->next));
ff0d69de 1424 node->next = prev->next;
1ee8f000 1425 prev->next = flag_bucket(node);
ff0d69de
LJ
1426 }
1427 }
1428}
1429
0422d92c 1430struct cds_lfht *_cds_lfht_new(unsigned long init_size,
0722081a 1431 unsigned long min_nr_alloc_buckets,
747d725c 1432 unsigned long max_nr_buckets,
b8af5011 1433 int flags,
0b6aa001 1434 const struct cds_lfht_mm_type *mm,
7b17c13e 1435 const struct rcu_flavor_struct *flavor,
b7d619b0 1436 pthread_attr_t *attr)
abc490a1 1437{
14044b37 1438 struct cds_lfht *ht;
24365af7 1439 unsigned long order;
abc490a1 1440
0722081a
LJ
1441 /* min_nr_alloc_buckets must be power of two */
1442 if (!min_nr_alloc_buckets || (min_nr_alloc_buckets & (min_nr_alloc_buckets - 1)))
5488222b 1443 return NULL;
747d725c 1444
8129be4e 1445 /* init_size must be power of two */
5488222b 1446 if (!init_size || (init_size & (init_size - 1)))
8129be4e 1447 return NULL;
747d725c 1448
c1888f3a
MD
1449 /*
1450 * Memory management plugin default.
1451 */
1452 if (!mm) {
5a2141a7
MD
1453 if (CAA_BITS_PER_LONG > 32
1454 && max_nr_buckets
c1888f3a
MD
1455 && max_nr_buckets <= (1ULL << 32)) {
1456 /*
1457 * For 64-bit architectures, with max number of
1458 * buckets small enough not to use the entire
1459 * 64-bit memory mapping space (and allowing a
1460 * fair number of hash table instances), use the
1461 * mmap allocator, which is faster than the
1462 * order allocator.
1463 */
1464 mm = &cds_lfht_mm_mmap;
1465 } else {
1466 /*
1467 * The fallback is to use the order allocator.
1468 */
1469 mm = &cds_lfht_mm_order;
1470 }
1471 }
1472
0b6aa001
LJ
1473 /* max_nr_buckets == 0 for order based mm means infinite */
1474 if (mm == &cds_lfht_mm_order && !max_nr_buckets)
747d725c
LJ
1475 max_nr_buckets = 1UL << (MAX_TABLE_ORDER - 1);
1476
1477 /* max_nr_buckets must be power of two */
1478 if (!max_nr_buckets || (max_nr_buckets & (max_nr_buckets - 1)))
1479 return NULL;
1480
0722081a 1481 min_nr_alloc_buckets = max(min_nr_alloc_buckets, MIN_TABLE_SIZE);
d0d8f9aa 1482 init_size = max(init_size, MIN_TABLE_SIZE);
747d725c
LJ
1483 max_nr_buckets = max(max_nr_buckets, min_nr_alloc_buckets);
1484 init_size = min(init_size, max_nr_buckets);
0b6aa001
LJ
1485
1486 ht = mm->alloc_cds_lfht(min_nr_alloc_buckets, max_nr_buckets);
b7d619b0 1487 assert(ht);
0b6aa001
LJ
1488 assert(ht->mm == mm);
1489 assert(ht->bucket_at == mm->bucket_at);
1490
b5d6b20f 1491 ht->flags = flags;
7b17c13e 1492 ht->flavor = flavor;
b7d619b0 1493 ht->resize_attr = attr;
5afadd12 1494 alloc_split_items_count(ht);
abc490a1
MD
1495 /* this mutex should not nest in read-side C.S. */
1496 pthread_mutex_init(&ht->resize_mutex, NULL);
5bc6b66f 1497 order = cds_lfht_get_count_order_ulong(init_size);
7b3893e4 1498 ht->resize_target = 1UL << order;
1ee8f000 1499 cds_lfht_create_bucket(ht, 1UL << order);
7b3893e4 1500 ht->size = 1UL << order;
abc490a1
MD
1501 return ht;
1502}
1503
6f554439 1504void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
996ff57c 1505 cds_lfht_match_fct match, const void *key,
6f554439 1506 struct cds_lfht_iter *iter)
2ed95849 1507{
04db56f8 1508 struct cds_lfht_node *node, *next, *bucket;
0422d92c 1509 unsigned long reverse_hash, size;
2ed95849 1510
abc490a1 1511 reverse_hash = bit_reverse_ulong(hash);
464a1ec9 1512
7b3893e4 1513 size = rcu_dereference(ht->size);
04db56f8 1514 bucket = lookup_bucket(ht, size, hash);
1ee8f000 1515 /* We can always skip the bucket node initially */
04db56f8 1516 node = rcu_dereference(bucket->next);
bb7b2f26 1517 node = clear_flag(node);
2ed95849 1518 for (;;) {
8ed51e04 1519 if (caa_unlikely(is_end(node))) {
96ad1112 1520 node = next = NULL;
abc490a1 1521 break;
bb7b2f26 1522 }
04db56f8 1523 if (caa_unlikely(node->reverse_hash > reverse_hash)) {
96ad1112 1524 node = next = NULL;
abc490a1 1525 break;
2ed95849 1526 }
04db56f8 1527 next = rcu_dereference(node->next);
7f52427b 1528 assert(node == clear_flag(node));
8ed51e04 1529 if (caa_likely(!is_removed(next))
1ee8f000 1530 && !is_bucket(next)
04db56f8 1531 && node->reverse_hash == reverse_hash
0422d92c 1532 && caa_likely(match(node, key))) {
273399de 1533 break;
2ed95849 1534 }
1b81fe1a 1535 node = clear_flag(next);
2ed95849 1536 }
a85eff52 1537 assert(!node || !is_bucket(CMM_LOAD_SHARED(node->next)));
adc0de68
MD
1538 iter->node = node;
1539 iter->next = next;
abc490a1 1540}
e0ba718a 1541
0422d92c 1542void cds_lfht_next_duplicate(struct cds_lfht *ht, cds_lfht_match_fct match,
996ff57c 1543 const void *key, struct cds_lfht_iter *iter)
a481e5ff 1544{
adc0de68 1545 struct cds_lfht_node *node, *next;
a481e5ff 1546 unsigned long reverse_hash;
a481e5ff 1547
adc0de68 1548 node = iter->node;
04db56f8 1549 reverse_hash = node->reverse_hash;
adc0de68 1550 next = iter->next;
a481e5ff
MD
1551 node = clear_flag(next);
1552
1553 for (;;) {
8ed51e04 1554 if (caa_unlikely(is_end(node))) {
96ad1112 1555 node = next = NULL;
a481e5ff 1556 break;
bb7b2f26 1557 }
04db56f8 1558 if (caa_unlikely(node->reverse_hash > reverse_hash)) {
96ad1112 1559 node = next = NULL;
a481e5ff
MD
1560 break;
1561 }
04db56f8 1562 next = rcu_dereference(node->next);
8ed51e04 1563 if (caa_likely(!is_removed(next))
1ee8f000 1564 && !is_bucket(next)
04db56f8 1565 && caa_likely(match(node, key))) {
a481e5ff
MD
1566 break;
1567 }
1568 node = clear_flag(next);
1569 }
a85eff52 1570 assert(!node || !is_bucket(CMM_LOAD_SHARED(node->next)));
adc0de68
MD
1571 iter->node = node;
1572 iter->next = next;
a481e5ff
MD
1573}
1574
4e9b9fbf
MD
1575void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter)
1576{
1577 struct cds_lfht_node *node, *next;
1578
853395e1 1579 node = clear_flag(iter->next);
4e9b9fbf 1580 for (;;) {
8ed51e04 1581 if (caa_unlikely(is_end(node))) {
4e9b9fbf
MD
1582 node = next = NULL;
1583 break;
1584 }
04db56f8 1585 next = rcu_dereference(node->next);
8ed51e04 1586 if (caa_likely(!is_removed(next))
1ee8f000 1587 && !is_bucket(next)) {
4e9b9fbf
MD
1588 break;
1589 }
1590 node = clear_flag(next);
1591 }
a85eff52 1592 assert(!node || !is_bucket(CMM_LOAD_SHARED(node->next)));
4e9b9fbf
MD
1593 iter->node = node;
1594 iter->next = next;
1595}
1596
1597void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter)
1598{
4e9b9fbf 1599 /*
1ee8f000 1600 * Get next after first bucket node. The first bucket node is the
4e9b9fbf
MD
1601 * first node of the linked list.
1602 */
9d72a73f 1603 iter->next = bucket_at(ht, 0)->next;
4e9b9fbf
MD
1604 cds_lfht_next(ht, iter);
1605}
1606
0422d92c
MD
1607void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
1608 struct cds_lfht_node *node)
abc490a1 1609{
0422d92c 1610 unsigned long size;
ab7d5fc6 1611
709bacf9 1612 node->reverse_hash = bit_reverse_ulong(hash);
7b3893e4 1613 size = rcu_dereference(ht->size);
91a75cc5 1614 _cds_lfht_add(ht, hash, NULL, NULL, size, node, NULL, 0);
14360f1c 1615 ht_count_add(ht, size, hash);
3eca1b8c
MD
1616}
1617
14044b37 1618struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
6f554439 1619 unsigned long hash,
0422d92c 1620 cds_lfht_match_fct match,
996ff57c 1621 const void *key,
48ed1c18 1622 struct cds_lfht_node *node)
3eca1b8c 1623{
0422d92c 1624 unsigned long size;
83beee94 1625 struct cds_lfht_iter iter;
3eca1b8c 1626
709bacf9 1627 node->reverse_hash = bit_reverse_ulong(hash);
7b3893e4 1628 size = rcu_dereference(ht->size);
91a75cc5 1629 _cds_lfht_add(ht, hash, match, key, size, node, &iter, 0);
83beee94 1630 if (iter.node == node)
14360f1c 1631 ht_count_add(ht, size, hash);
83beee94 1632 return iter.node;
2ed95849
MD
1633}
1634
9357c415 1635struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
6f554439 1636 unsigned long hash,
0422d92c 1637 cds_lfht_match_fct match,
996ff57c 1638 const void *key,
48ed1c18
MD
1639 struct cds_lfht_node *node)
1640{
0422d92c 1641 unsigned long size;
83beee94 1642 struct cds_lfht_iter iter;
48ed1c18 1643
709bacf9 1644 node->reverse_hash = bit_reverse_ulong(hash);
7b3893e4 1645 size = rcu_dereference(ht->size);
83beee94 1646 for (;;) {
91a75cc5 1647 _cds_lfht_add(ht, hash, match, key, size, node, &iter, 0);
83beee94 1648 if (iter.node == node) {
14360f1c 1649 ht_count_add(ht, size, hash);
83beee94
MD
1650 return NULL;
1651 }
1652
1653 if (!_cds_lfht_replace(ht, size, iter.node, iter.next, node))
1654 return iter.node;
1655 }
48ed1c18
MD
1656}
1657
2e79c445
MD
1658int cds_lfht_replace(struct cds_lfht *ht,
1659 struct cds_lfht_iter *old_iter,
1660 unsigned long hash,
1661 cds_lfht_match_fct match,
1662 const void *key,
9357c415
MD
1663 struct cds_lfht_node *new_node)
1664{
1665 unsigned long size;
1666
709bacf9 1667 new_node->reverse_hash = bit_reverse_ulong(hash);
2e79c445
MD
1668 if (!old_iter->node)
1669 return -ENOENT;
1670 if (caa_unlikely(old_iter->node->reverse_hash != new_node->reverse_hash))
1671 return -EINVAL;
1672 if (caa_unlikely(!match(old_iter->node, key)))
1673 return -EINVAL;
7b3893e4 1674 size = rcu_dereference(ht->size);
9357c415
MD
1675 return _cds_lfht_replace(ht, size, old_iter->node, old_iter->next,
1676 new_node);
1677}
1678
bc8c3c74 1679int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node)
2ed95849 1680{
95bc7fb9 1681 unsigned long size;
df44348d 1682 int ret;
abc490a1 1683
7b3893e4 1684 size = rcu_dereference(ht->size);
bc8c3c74 1685 ret = _cds_lfht_del(ht, size, node);
14360f1c 1686 if (!ret) {
95bc7fb9
MD
1687 unsigned long hash;
1688
bc8c3c74 1689 hash = bit_reverse_ulong(node->reverse_hash);
14360f1c
LJ
1690 ht_count_del(ht, size, hash);
1691 }
df44348d 1692 return ret;
2ed95849 1693}
ab7d5fc6 1694
df55172a
MD
1695int cds_lfht_is_node_deleted(struct cds_lfht_node *node)
1696{
a85eff52 1697 return is_removed(CMM_LOAD_SHARED(node->next));
df55172a
MD
1698}
1699
abc490a1 1700static
1ee8f000 1701int cds_lfht_delete_bucket(struct cds_lfht *ht)
674f7a69 1702{
14044b37 1703 struct cds_lfht_node *node;
4105056a 1704 unsigned long order, i, size;
674f7a69 1705
abc490a1 1706 /* Check that the table is empty */
9d72a73f 1707 node = bucket_at(ht, 0);
abc490a1 1708 do {
04db56f8 1709 node = clear_flag(node)->next;
1ee8f000 1710 if (!is_bucket(node))
abc490a1 1711 return -EPERM;
273399de 1712 assert(!is_removed(node));
2f943cd7 1713 assert(!is_removal_owner(node));
bb7b2f26 1714 } while (!is_end(node));
4105056a
MD
1715 /*
1716 * size accessed without rcu_dereference because hash table is
1717 * being destroyed.
1718 */
7b3893e4 1719 size = ht->size;
1f67ba50 1720 /* Internal sanity check: all nodes left should be buckets */
48f1b16d
LJ
1721 for (i = 0; i < size; i++) {
1722 node = bucket_at(ht, i);
1723 dbg_printf("delete bucket: index %lu expected hash %lu hash %lu\n",
1724 i, i, bit_reverse_ulong(node->reverse_hash));
1725 assert(is_bucket(node->next));
1726 }
24365af7 1727
5bc6b66f 1728 for (order = cds_lfht_get_count_order_ulong(size); (long)order >= 0; order--)
48f1b16d 1729 cds_lfht_free_bucket_table(ht, order);
5488222b 1730
abc490a1 1731 return 0;
674f7a69
MD
1732}
1733
1734/*
1735 * Should only be called when no more concurrent readers nor writers can
1736 * possibly access the table.
1737 */
b7d619b0 1738int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr)
674f7a69 1739{
a1e5e232 1740 int ret, was_online;
5e28c532 1741
848d4088 1742 /* Wait for in-flight resize operations to complete */
24953e08
MD
1743 _CMM_STORE_SHARED(ht->in_progress_destroy, 1);
1744 cmm_smp_mb(); /* Store destroy before load resize */
a1e5e232
MD
1745 was_online = ht->flavor->read_ongoing();
1746 if (was_online)
1747 ht->flavor->thread_offline();
10e68472
MD
1748 /* Calling with RCU read-side held is an error. */
1749 if (ht->flavor->read_ongoing()) {
1750 ret = -EINVAL;
1751 if (was_online)
1752 ht->flavor->thread_online();
1753 goto end;
1754 }
848d4088
MD
1755 while (uatomic_read(&ht->in_progress_resize))
1756 poll(NULL, 0, 100); /* wait for 100ms */
a1e5e232
MD
1757 if (was_online)
1758 ht->flavor->thread_online();
1ee8f000 1759 ret = cds_lfht_delete_bucket(ht);
abc490a1
MD
1760 if (ret)
1761 return ret;
5afadd12 1762 free_split_items_count(ht);
b7d619b0
MD
1763 if (attr)
1764 *attr = ht->resize_attr;
98808fb1 1765 poison_free(ht);
10e68472 1766end:
5e28c532 1767 return ret;
674f7a69
MD
1768}
1769
14044b37 1770void cds_lfht_count_nodes(struct cds_lfht *ht,
d933dd0e 1771 long *approx_before,
273399de 1772 unsigned long *count,
d933dd0e 1773 long *approx_after)
273399de 1774{
14044b37 1775 struct cds_lfht_node *node, *next;
caf3653d 1776 unsigned long nr_bucket = 0, nr_removed = 0;
273399de 1777
7ed7682f 1778 *approx_before = 0;
5afadd12 1779 if (ht->split_count) {
973e5e1b
MD
1780 int i;
1781
4c42f1b8
LJ
1782 for (i = 0; i < split_count_mask + 1; i++) {
1783 *approx_before += uatomic_read(&ht->split_count[i].add);
1784 *approx_before -= uatomic_read(&ht->split_count[i].del);
973e5e1b
MD
1785 }
1786 }
1787
273399de 1788 *count = 0;
273399de 1789
1ee8f000 1790 /* Count non-bucket nodes in the table */
9d72a73f 1791 node = bucket_at(ht, 0);
273399de 1792 do {
04db56f8 1793 next = rcu_dereference(node->next);
b198f0fd 1794 if (is_removed(next)) {
1ee8f000 1795 if (!is_bucket(next))
caf3653d 1796 (nr_removed)++;
973e5e1b 1797 else
1ee8f000
LJ
1798 (nr_bucket)++;
1799 } else if (!is_bucket(next))
273399de 1800 (*count)++;
24365af7 1801 else
1ee8f000 1802 (nr_bucket)++;
273399de 1803 node = clear_flag(next);
bb7b2f26 1804 } while (!is_end(node));
caf3653d 1805 dbg_printf("number of logically removed nodes: %lu\n", nr_removed);
1ee8f000 1806 dbg_printf("number of bucket nodes: %lu\n", nr_bucket);
7ed7682f 1807 *approx_after = 0;
5afadd12 1808 if (ht->split_count) {
973e5e1b
MD
1809 int i;
1810
4c42f1b8
LJ
1811 for (i = 0; i < split_count_mask + 1; i++) {
1812 *approx_after += uatomic_read(&ht->split_count[i].add);
1813 *approx_after -= uatomic_read(&ht->split_count[i].del);
973e5e1b
MD
1814 }
1815 }
273399de
MD
1816}
1817
1475579c 1818/* called with resize mutex held */
abc490a1 1819static
4105056a 1820void _do_cds_lfht_grow(struct cds_lfht *ht,
1475579c 1821 unsigned long old_size, unsigned long new_size)
abc490a1 1822{
1475579c 1823 unsigned long old_order, new_order;
1475579c 1824
5bc6b66f
MD
1825 old_order = cds_lfht_get_count_order_ulong(old_size);
1826 new_order = cds_lfht_get_count_order_ulong(new_size);
1a401918
LJ
1827 dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
1828 old_size, old_order, new_size, new_order);
1475579c 1829 assert(new_size > old_size);
93d46c39 1830 init_table(ht, old_order + 1, new_order);
abc490a1
MD
1831}
1832
1833/* called with resize mutex held */
1834static
4105056a 1835void _do_cds_lfht_shrink(struct cds_lfht *ht,
1475579c 1836 unsigned long old_size, unsigned long new_size)
464a1ec9 1837{
1475579c 1838 unsigned long old_order, new_order;
464a1ec9 1839
d0d8f9aa 1840 new_size = max(new_size, MIN_TABLE_SIZE);
5bc6b66f
MD
1841 old_order = cds_lfht_get_count_order_ulong(old_size);
1842 new_order = cds_lfht_get_count_order_ulong(new_size);
1a401918
LJ
1843 dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
1844 old_size, old_order, new_size, new_order);
1475579c 1845 assert(new_size < old_size);
1475579c 1846
1ee8f000 1847 /* Remove and unlink all bucket nodes to remove. */
93d46c39 1848 fini_table(ht, new_order + 1, old_order);
464a1ec9
MD
1849}
1850
1475579c
MD
1851
1852/* called with resize mutex held */
1853static
1854void _do_cds_lfht_resize(struct cds_lfht *ht)
1855{
1856 unsigned long new_size, old_size;
4105056a
MD
1857
1858 /*
1859 * Resize table, re-do if the target size has changed under us.
1860 */
1861 do {
d2be3620
MD
1862 assert(uatomic_read(&ht->in_progress_resize));
1863 if (CMM_LOAD_SHARED(ht->in_progress_destroy))
1864 break;
7b3893e4
LJ
1865 ht->resize_initiated = 1;
1866 old_size = ht->size;
1867 new_size = CMM_LOAD_SHARED(ht->resize_target);
4105056a
MD
1868 if (old_size < new_size)
1869 _do_cds_lfht_grow(ht, old_size, new_size);
1870 else if (old_size > new_size)
1871 _do_cds_lfht_shrink(ht, old_size, new_size);
7b3893e4 1872 ht->resize_initiated = 0;
4105056a
MD
1873 /* write resize_initiated before read resize_target */
1874 cmm_smp_mb();
7b3893e4 1875 } while (ht->size != CMM_LOAD_SHARED(ht->resize_target));
1475579c
MD
1876}
1877
abc490a1 1878static
ab65b890 1879unsigned long resize_target_grow(struct cds_lfht *ht, unsigned long new_size)
464a1ec9 1880{
7b3893e4 1881 return _uatomic_xchg_monotonic_increase(&ht->resize_target, new_size);
464a1ec9
MD
1882}
1883
1475579c 1884static
4105056a 1885void resize_target_update_count(struct cds_lfht *ht,
b8af5011 1886 unsigned long count)
1475579c 1887{
d0d8f9aa 1888 count = max(count, MIN_TABLE_SIZE);
747d725c 1889 count = min(count, ht->max_nr_buckets);
7b3893e4 1890 uatomic_set(&ht->resize_target, count);
1475579c
MD
1891}
1892
1893void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size)
464a1ec9 1894{
a1e5e232
MD
1895 int was_online;
1896
a1e5e232
MD
1897 was_online = ht->flavor->read_ongoing();
1898 if (was_online)
1899 ht->flavor->thread_offline();
10e68472
MD
1900 /* Calling with RCU read-side held is an error. */
1901 if (ht->flavor->read_ongoing()) {
1902 static int print_once;
1903
1904 if (!CMM_LOAD_SHARED(print_once))
1905 fprintf(stderr, "[error] rculfhash: cds_lfht_resize "
1906 "called with RCU read-side lock held.\n");
1907 CMM_STORE_SHARED(print_once, 1);
1908 assert(0);
1909 goto end;
1910 }
1911 resize_target_update_count(ht, new_size);
1912 CMM_STORE_SHARED(ht->resize_initiated, 1);
1475579c
MD
1913 pthread_mutex_lock(&ht->resize_mutex);
1914 _do_cds_lfht_resize(ht);
1915 pthread_mutex_unlock(&ht->resize_mutex);
10e68472 1916end:
a1e5e232
MD
1917 if (was_online)
1918 ht->flavor->thread_online();
abc490a1 1919}
464a1ec9 1920
abc490a1
MD
1921static
1922void do_resize_cb(struct rcu_head *head)
1923{
1924 struct rcu_resize_work *work =
1925 caa_container_of(head, struct rcu_resize_work, head);
14044b37 1926 struct cds_lfht *ht = work->ht;
abc490a1 1927
7b17c13e 1928 ht->flavor->thread_offline();
abc490a1 1929 pthread_mutex_lock(&ht->resize_mutex);
14044b37 1930 _do_cds_lfht_resize(ht);
abc490a1 1931 pthread_mutex_unlock(&ht->resize_mutex);
7b17c13e 1932 ht->flavor->thread_online();
98808fb1 1933 poison_free(work);
848d4088
MD
1934 cmm_smp_mb(); /* finish resize before decrement */
1935 uatomic_dec(&ht->in_progress_resize);
464a1ec9
MD
1936}
1937
abc490a1 1938static
f1f119ee 1939void __cds_lfht_resize_lazy_launch(struct cds_lfht *ht)
ab7d5fc6 1940{
abc490a1
MD
1941 struct rcu_resize_work *work;
1942
4105056a
MD
1943 /* Store resize_target before read resize_initiated */
1944 cmm_smp_mb();
7b3893e4 1945 if (!CMM_LOAD_SHARED(ht->resize_initiated)) {
848d4088 1946 uatomic_inc(&ht->in_progress_resize);
59290e9d 1947 cmm_smp_mb(); /* increment resize count before load destroy */
ed35e6d8
MD
1948 if (CMM_LOAD_SHARED(ht->in_progress_destroy)) {
1949 uatomic_dec(&ht->in_progress_resize);
59290e9d 1950 return;
ed35e6d8 1951 }
f9830efd 1952 work = malloc(sizeof(*work));
741f378e
MD
1953 if (work == NULL) {
1954 dbg_printf("error allocating resize work, bailing out\n");
1955 uatomic_dec(&ht->in_progress_resize);
1956 return;
1957 }
f9830efd 1958 work->ht = ht;
7b17c13e 1959 ht->flavor->update_call_rcu(&work->head, do_resize_cb);
7b3893e4 1960 CMM_STORE_SHARED(ht->resize_initiated, 1);
f9830efd 1961 }
ab7d5fc6 1962}
3171717f 1963
f1f119ee
LJ
1964static
1965void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth)
1966{
1967 unsigned long target_size = size << growth;
1968
747d725c 1969 target_size = min(target_size, ht->max_nr_buckets);
f1f119ee
LJ
1970 if (resize_target_grow(ht, target_size) >= target_size)
1971 return;
1972
1973 __cds_lfht_resize_lazy_launch(ht);
1974}
1975
89bb121d
LJ
1976/*
1977 * We favor grow operations over shrink. A shrink operation never occurs
1978 * if a grow operation is queued for lazy execution. A grow operation
1979 * cancels any pending shrink lazy execution.
1980 */
3171717f 1981static
4105056a 1982void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
3171717f
MD
1983 unsigned long count)
1984{
b8af5011
MD
1985 if (!(ht->flags & CDS_LFHT_AUTO_RESIZE))
1986 return;
d0d8f9aa 1987 count = max(count, MIN_TABLE_SIZE);
747d725c 1988 count = min(count, ht->max_nr_buckets);
89bb121d
LJ
1989 if (count == size)
1990 return; /* Already the right size, no resize needed */
1991 if (count > size) { /* lazy grow */
1992 if (resize_target_grow(ht, count) >= count)
1993 return;
1994 } else { /* lazy shrink */
1995 for (;;) {
1996 unsigned long s;
1997
7b3893e4 1998 s = uatomic_cmpxchg(&ht->resize_target, size, count);
89bb121d
LJ
1999 if (s == size)
2000 break; /* no resize needed */
2001 if (s > size)
2002 return; /* growing is/(was just) in progress */
2003 if (s <= count)
2004 return; /* some other thread do shrink */
2005 size = s;
2006 }
2007 }
f1f119ee 2008 __cds_lfht_resize_lazy_launch(ht);
3171717f 2009}
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