rculfhash: reorder cds_lfht for smaller cache footprint in fast-paths
[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
37 * table lookups and use the returned objects safely by delaying
38 * memory reclaim of a grace period.
39 * - Add and remove operations are lock-free, and do not need to
40 * allocate memory. They need to be executed within RCU read-side
41 * critical section to ensure the objects they read are valid and to
42 * deal with the cmpxchg ABA problem.
43 * - add and add_unique operations are supported. add_unique checks if
44 * the node key already exists in the hash table. It ensures no key
45 * duplicata exists.
46 * - The resize operation executes concurrently with add/remove/lookup.
47 * - Hash table nodes are contained within a split-ordered list. This
48 * list is ordered by incrementing reversed-bits-hash value.
1ee8f000 49 * - An index of bucket nodes is kept. These bucket nodes are the hash
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50 * table "buckets", and they are also chained together in the
51 * split-ordered list, which allows recursive expansion.
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52 * - The resize operation for small tables only allows expanding the hash table.
53 * It is triggered automatically by detecting long chains in the add
54 * operation.
55 * - The resize operation for larger tables (and available through an
56 * API) allows both expanding and shrinking the hash table.
4c42f1b8 57 * - Split-counters are used to keep track of the number of
1475579c 58 * nodes within the hash table for automatic resize triggering.
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59 * - Resize operation initiated by long chain detection is executed by a
60 * call_rcu thread, which keeps lock-freedom of add and remove.
61 * - Resize operations are protected by a mutex.
62 * - The removal operation is split in two parts: first, a "removed"
63 * flag is set in the next pointer within the node to remove. Then,
64 * a "garbage collection" is performed in the bucket containing the
65 * removed node (from the start of the bucket up to the removed node).
66 * All encountered nodes with "removed" flag set in their next
67 * pointers are removed from the linked-list. If the cmpxchg used for
68 * removal fails (due to concurrent garbage-collection or concurrent
69 * add), we retry from the beginning of the bucket. This ensures that
70 * the node with "removed" flag set is removed from the hash table
71 * (not visible to lookups anymore) before the RCU read-side critical
72 * section held across removal ends. Furthermore, this ensures that
73 * the node with "removed" flag set is removed from the linked-list
74 * before its memory is reclaimed. Only the thread which removal
75 * successfully set the "removed" flag (with a cmpxchg) into a node's
76 * next pointer is considered to have succeeded its removal (and thus
77 * owns the node to reclaim). Because we garbage-collect starting from
1ee8f000 78 * an invariant node (the start-of-bucket bucket node) up to the
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79 * "removed" node (or find a reverse-hash that is higher), we are sure
80 * that a successful traversal of the chain leads to a chain that is
81 * present in the linked-list (the start node is never removed) and
82 * that is does not contain the "removed" node anymore, even if
83 * concurrent delete/add operations are changing the structure of the
84 * list concurrently.
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85 * - The add operation performs gargage collection of buckets if it
86 * encounters nodes with removed flag set in the bucket where it wants
87 * to add its new node. This ensures lock-freedom of add operation by
88 * helping the remover unlink nodes from the list rather than to wait
89 * for it do to so.
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90 * - A RCU "order table" indexed by log2(hash index) is copied and
91 * expanded by the resize operation. This order table allows finding
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92 * the "bucket node" tables.
93 * - There is one bucket node table per hash index order. The size of
94 * each bucket node table is half the number of hashes contained in
93d46c39 95 * this order (except for order 0).
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96 * - synchronzie_rcu is used to garbage-collect the old bucket node table.
97 * - The per-order bucket node tables contain a compact version of the
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98 * hash table nodes. These tables are invariant after they are
99 * populated into the hash table.
93d46c39 100 *
1ee8f000 101 * Bucket node tables:
93d46c39 102 *
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103 * hash table hash table the last all bucket node tables
104 * order size bucket node 0 1 2 3 4 5 6(index)
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105 * table size
106 * 0 1 1 1
107 * 1 2 1 1 1
108 * 2 4 2 1 1 2
109 * 3 8 4 1 1 2 4
110 * 4 16 8 1 1 2 4 8
111 * 5 32 16 1 1 2 4 8 16
112 * 6 64 32 1 1 2 4 8 16 32
113 *
1ee8f000 114 * When growing/shrinking, we only focus on the last bucket node table
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115 * which size is (!order ? 1 : (1 << (order -1))).
116 *
117 * Example for growing/shrinking:
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118 * grow hash table from order 5 to 6: init the index=6 bucket node table
119 * shrink hash table from order 6 to 5: fini the index=6 bucket node table
93d46c39 120 *
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121 * A bit of ascii art explanation:
122 *
123 * Order index is the off-by-one compare to the actual power of 2 because
124 * we use index 0 to deal with the 0 special-case.
125 *
126 * This shows the nodes for a small table ordered by reversed bits:
127 *
128 * bits reverse
129 * 0 000 000
130 * 4 100 001
131 * 2 010 010
132 * 6 110 011
133 * 1 001 100
134 * 5 101 101
135 * 3 011 110
136 * 7 111 111
137 *
138 * This shows the nodes in order of non-reversed bits, linked by
139 * reversed-bit order.
140 *
141 * order bits reverse
142 * 0 0 000 000
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143 * 1 | 1 001 100 <-
144 * 2 | | 2 010 010 <- |
f6fdd688 145 * | | | 3 011 110 | <- |
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146 * 3 -> | | | 4 100 001 | |
147 * -> | | 5 101 101 |
148 * -> | 6 110 011
149 * -> 7 111 111
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150 */
151
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152#define _LGPL_SOURCE
153#include <stdlib.h>
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154#include <errno.h>
155#include <assert.h>
156#include <stdio.h>
abc490a1 157#include <stdint.h>
f000907d 158#include <string.h>
e0ba718a 159
15cfbec7 160#include "config.h"
2ed95849 161#include <urcu.h>
abc490a1 162#include <urcu-call-rcu.h>
7b17c13e 163#include <urcu-flavor.h>
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164#include <urcu/arch.h>
165#include <urcu/uatomic.h>
a42cc659 166#include <urcu/compiler.h>
abc490a1 167#include <urcu/rculfhash.h>
0b6aa001 168#include <rculfhash-internal.h>
5e28c532 169#include <stdio.h>
464a1ec9 170#include <pthread.h>
44395fb7 171
f8994aee 172/*
4c42f1b8 173 * Split-counters lazily update the global counter each 1024
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174 * addition/removal. It automatically keeps track of resize required.
175 * We use the bucket length as indicator for need to expand for small
176 * tables and machines lacking per-cpu data suppport.
177 */
178#define COUNT_COMMIT_ORDER 10
4ddbb355 179#define DEFAULT_SPLIT_COUNT_MASK 0xFUL
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180#define CHAIN_LEN_TARGET 1
181#define CHAIN_LEN_RESIZE_THRESHOLD 3
2ed95849 182
cd95516d 183/*
76a73da8 184 * Define the minimum table size.
cd95516d 185 */
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186#define MIN_TABLE_ORDER 0
187#define MIN_TABLE_SIZE (1UL << MIN_TABLE_ORDER)
cd95516d 188
b7d619b0 189/*
1ee8f000 190 * Minimum number of bucket nodes to touch per thread to parallelize grow/shrink.
b7d619b0 191 */
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192#define MIN_PARTITION_PER_THREAD_ORDER 12
193#define MIN_PARTITION_PER_THREAD (1UL << MIN_PARTITION_PER_THREAD_ORDER)
b7d619b0 194
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195/*
196 * The removed flag needs to be updated atomically with the pointer.
48ed1c18 197 * It indicates that no node must attach to the node scheduled for
b198f0fd 198 * removal, and that node garbage collection must be performed.
1ee8f000 199 * The bucket flag does not require to be updated atomically with the
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200 * pointer, but it is added as a pointer low bit flag to save space.
201 */
d37166c6 202#define REMOVED_FLAG (1UL << 0)
1ee8f000 203#define BUCKET_FLAG (1UL << 1)
b198f0fd 204#define FLAGS_MASK ((1UL << 2) - 1)
d37166c6 205
bb7b2f26 206/* Value of the end pointer. Should not interact with flags. */
f9c80341 207#define END_VALUE NULL
bb7b2f26 208
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209/*
210 * ht_items_count: Split-counters counting the number of node addition
211 * and removal in the table. Only used if the CDS_LFHT_ACCOUNTING flag
212 * is set at hash table creation.
213 *
214 * These are free-running counters, never reset to zero. They count the
215 * number of add/remove, and trigger every (1 << COUNT_COMMIT_ORDER)
216 * operations to update the global counter. We choose a power-of-2 value
217 * for the trigger to deal with 32 or 64-bit overflow of the counter.
218 */
df44348d 219struct ht_items_count {
860d07e8 220 unsigned long add, del;
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221} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
222
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223/*
224 * rcu_resize_work: Contains arguments passed to RCU worker thread
225 * responsible for performing lazy resize.
226 */
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227struct rcu_resize_work {
228 struct rcu_head head;
14044b37 229 struct cds_lfht *ht;
abc490a1 230};
2ed95849 231
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232/*
233 * partition_resize_work: Contains arguments passed to worker threads
234 * executing the hash table resize on partitions of the hash table
235 * assigned to each processor's worker thread.
236 */
b7d619b0 237struct partition_resize_work {
1af6e26e 238 pthread_t thread_id;
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239 struct cds_lfht *ht;
240 unsigned long i, start, len;
241 void (*fct)(struct cds_lfht *ht, unsigned long i,
242 unsigned long start, unsigned long len);
243};
244
76a73da8 245static
83beee94 246void _cds_lfht_add(struct cds_lfht *ht,
0422d92c 247 cds_lfht_match_fct match,
996ff57c 248 const void *key,
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249 unsigned long size,
250 struct cds_lfht_node *node,
251 struct cds_lfht_iter *unique_ret,
1ee8f000 252 int bucket);
48ed1c18 253
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254/*
255 * Algorithm to reverse bits in a word by lookup table, extended to
256 * 64-bit words.
f9830efd 257 * Source:
abc490a1 258 * http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable
f9830efd 259 * Originally from Public Domain.
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260 */
261
262static const uint8_t BitReverseTable256[256] =
2ed95849 263{
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264#define R2(n) (n), (n) + 2*64, (n) + 1*64, (n) + 3*64
265#define R4(n) R2(n), R2((n) + 2*16), R2((n) + 1*16), R2((n) + 3*16)
266#define R6(n) R4(n), R4((n) + 2*4 ), R4((n) + 1*4 ), R4((n) + 3*4 )
267 R6(0), R6(2), R6(1), R6(3)
268};
269#undef R2
270#undef R4
271#undef R6
2ed95849 272
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273static
274uint8_t bit_reverse_u8(uint8_t v)
275{
276 return BitReverseTable256[v];
277}
ab7d5fc6 278
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279static __attribute__((unused))
280uint32_t bit_reverse_u32(uint32_t v)
281{
282 return ((uint32_t) bit_reverse_u8(v) << 24) |
283 ((uint32_t) bit_reverse_u8(v >> 8) << 16) |
284 ((uint32_t) bit_reverse_u8(v >> 16) << 8) |
285 ((uint32_t) bit_reverse_u8(v >> 24));
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286}
287
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288static __attribute__((unused))
289uint64_t bit_reverse_u64(uint64_t v)
2ed95849 290{
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291 return ((uint64_t) bit_reverse_u8(v) << 56) |
292 ((uint64_t) bit_reverse_u8(v >> 8) << 48) |
293 ((uint64_t) bit_reverse_u8(v >> 16) << 40) |
294 ((uint64_t) bit_reverse_u8(v >> 24) << 32) |
295 ((uint64_t) bit_reverse_u8(v >> 32) << 24) |
296 ((uint64_t) bit_reverse_u8(v >> 40) << 16) |
297 ((uint64_t) bit_reverse_u8(v >> 48) << 8) |
298 ((uint64_t) bit_reverse_u8(v >> 56));
299}
300
301static
302unsigned long bit_reverse_ulong(unsigned long v)
303{
304#if (CAA_BITS_PER_LONG == 32)
305 return bit_reverse_u32(v);
306#else
307 return bit_reverse_u64(v);
308#endif
309}
310
f9830efd 311/*
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312 * fls: returns the position of the most significant bit.
313 * Returns 0 if no bit is set, else returns the position of the most
314 * significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit).
f9830efd 315 */
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316#if defined(__i386) || defined(__x86_64)
317static inline
318unsigned int fls_u32(uint32_t x)
f9830efd 319{
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320 int r;
321
322 asm("bsrl %1,%0\n\t"
323 "jnz 1f\n\t"
324 "movl $-1,%0\n\t"
325 "1:\n\t"
326 : "=r" (r) : "rm" (x));
327 return r + 1;
328}
329#define HAS_FLS_U32
330#endif
331
332#if defined(__x86_64)
333static inline
334unsigned int fls_u64(uint64_t x)
335{
336 long r;
337
338 asm("bsrq %1,%0\n\t"
339 "jnz 1f\n\t"
340 "movq $-1,%0\n\t"
341 "1:\n\t"
342 : "=r" (r) : "rm" (x));
343 return r + 1;
344}
345#define HAS_FLS_U64
346#endif
347
348#ifndef HAS_FLS_U64
349static __attribute__((unused))
350unsigned int fls_u64(uint64_t x)
351{
352 unsigned int r = 64;
353
354 if (!x)
355 return 0;
356
357 if (!(x & 0xFFFFFFFF00000000ULL)) {
358 x <<= 32;
359 r -= 32;
360 }
361 if (!(x & 0xFFFF000000000000ULL)) {
362 x <<= 16;
363 r -= 16;
364 }
365 if (!(x & 0xFF00000000000000ULL)) {
366 x <<= 8;
367 r -= 8;
368 }
369 if (!(x & 0xF000000000000000ULL)) {
370 x <<= 4;
371 r -= 4;
372 }
373 if (!(x & 0xC000000000000000ULL)) {
374 x <<= 2;
375 r -= 2;
376 }
377 if (!(x & 0x8000000000000000ULL)) {
378 x <<= 1;
379 r -= 1;
380 }
381 return r;
382}
383#endif
384
385#ifndef HAS_FLS_U32
386static __attribute__((unused))
387unsigned int fls_u32(uint32_t x)
388{
389 unsigned int r = 32;
f9830efd 390
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391 if (!x)
392 return 0;
393 if (!(x & 0xFFFF0000U)) {
394 x <<= 16;
395 r -= 16;
396 }
397 if (!(x & 0xFF000000U)) {
398 x <<= 8;
399 r -= 8;
400 }
401 if (!(x & 0xF0000000U)) {
402 x <<= 4;
403 r -= 4;
404 }
405 if (!(x & 0xC0000000U)) {
406 x <<= 2;
407 r -= 2;
408 }
409 if (!(x & 0x80000000U)) {
410 x <<= 1;
411 r -= 1;
412 }
413 return r;
414}
415#endif
416
417unsigned int fls_ulong(unsigned long x)
f9830efd 418{
6887cc5e 419#if (CAA_BITS_PER_LONG == 32)
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420 return fls_u32(x);
421#else
422 return fls_u64(x);
423#endif
424}
f9830efd 425
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426/*
427 * Return the minimum order for which x <= (1UL << order).
428 * Return -1 if x is 0.
429 */
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430int get_count_order_u32(uint32_t x)
431{
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432 if (!x)
433 return -1;
24365af7 434
920f8ef6 435 return fls_u32(x - 1);
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436}
437
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438/*
439 * Return the minimum order for which x <= (1UL << order).
440 * Return -1 if x is 0.
441 */
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442int get_count_order_ulong(unsigned long x)
443{
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444 if (!x)
445 return -1;
24365af7 446
920f8ef6 447 return fls_ulong(x - 1);
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448}
449
450static
ab65b890 451void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth);
f9830efd 452
f8994aee 453static
4105056a 454void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
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455 unsigned long count);
456
df44348d 457static long nr_cpus_mask = -1;
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458static long split_count_mask = -1;
459
4ddbb355 460#if defined(HAVE_SYSCONF)
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461static void ht_init_nr_cpus_mask(void)
462{
463 long maxcpus;
464
465 maxcpus = sysconf(_SC_NPROCESSORS_CONF);
466 if (maxcpus <= 0) {
467 nr_cpus_mask = -2;
468 return;
469 }
470 /*
471 * round up number of CPUs to next power of two, so we
472 * can use & for modulo.
473 */
474 maxcpus = 1UL << get_count_order_ulong(maxcpus);
475 nr_cpus_mask = maxcpus - 1;
476}
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477#else /* #if defined(HAVE_SYSCONF) */
478static void ht_init_nr_cpus_mask(void)
479{
480 nr_cpus_mask = -2;
481}
482#endif /* #else #if defined(HAVE_SYSCONF) */
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483
484static
5afadd12 485void alloc_split_items_count(struct cds_lfht *ht)
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486{
487 struct ht_items_count *count;
488
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489 if (nr_cpus_mask == -1) {
490 ht_init_nr_cpus_mask();
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491 if (nr_cpus_mask < 0)
492 split_count_mask = DEFAULT_SPLIT_COUNT_MASK;
493 else
494 split_count_mask = nr_cpus_mask;
df44348d 495 }
4c42f1b8 496
4ddbb355 497 assert(split_count_mask >= 0);
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498
499 if (ht->flags & CDS_LFHT_ACCOUNTING) {
500 ht->split_count = calloc(split_count_mask + 1, sizeof(*count));
501 assert(ht->split_count);
502 } else {
503 ht->split_count = NULL;
504 }
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505}
506
507static
5afadd12 508void free_split_items_count(struct cds_lfht *ht)
df44348d 509{
5afadd12 510 poison_free(ht->split_count);
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511}
512
14360f1c 513#if defined(HAVE_SCHED_GETCPU)
df44348d 514static
14360f1c 515int ht_get_split_count_index(unsigned long hash)
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516{
517 int cpu;
518
4c42f1b8 519 assert(split_count_mask >= 0);
df44348d 520 cpu = sched_getcpu();
8ed51e04 521 if (caa_unlikely(cpu < 0))
14360f1c 522 return hash & split_count_mask;
df44348d 523 else
4c42f1b8 524 return cpu & split_count_mask;
df44348d 525}
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526#else /* #if defined(HAVE_SCHED_GETCPU) */
527static
528int ht_get_split_count_index(unsigned long hash)
529{
530 return hash & split_count_mask;
531}
532#endif /* #else #if defined(HAVE_SCHED_GETCPU) */
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533
534static
14360f1c 535void ht_count_add(struct cds_lfht *ht, unsigned long size, unsigned long hash)
df44348d 536{
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537 unsigned long split_count;
538 int index;
df44348d 539
8ed51e04 540 if (caa_unlikely(!ht->split_count))
3171717f 541 return;
14360f1c 542 index = ht_get_split_count_index(hash);
4c42f1b8 543 split_count = uatomic_add_return(&ht->split_count[index].add, 1);
8ed51e04 544 if (caa_unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
e3ecefd6 545 long count;
df44348d 546
4c42f1b8 547 dbg_printf("add split count %lu\n", split_count);
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548 count = uatomic_add_return(&ht->count,
549 1UL << COUNT_COMMIT_ORDER);
550 /* If power of 2 */
551 if (!(count & (count - 1))) {
4105056a 552 if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) < size)
f8994aee 553 return;
e3ecefd6 554 dbg_printf("add set global %ld\n", count);
4105056a 555 cds_lfht_resize_lazy_count(ht, size,
6ea6bc67 556 count >> (CHAIN_LEN_TARGET - 1));
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557 }
558 }
559}
560
561static
14360f1c 562void ht_count_del(struct cds_lfht *ht, unsigned long size, unsigned long hash)
df44348d 563{
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564 unsigned long split_count;
565 int index;
df44348d 566
8ed51e04 567 if (caa_unlikely(!ht->split_count))
3171717f 568 return;
14360f1c 569 index = ht_get_split_count_index(hash);
4c42f1b8 570 split_count = uatomic_add_return(&ht->split_count[index].del, 1);
8ed51e04 571 if (caa_unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
e3ecefd6 572 long count;
df44348d 573
4c42f1b8 574 dbg_printf("del split count %lu\n", split_count);
df44348d 575 count = uatomic_add_return(&ht->count,
3171717f 576 -(1UL << COUNT_COMMIT_ORDER));
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577 /* If power of 2 */
578 if (!(count & (count - 1))) {
4105056a 579 if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) >= size)
f8994aee 580 return;
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581 dbg_printf("del set global %ld\n", count);
582 /*
c941bb9e 583 * Don't shrink table if the number of nodes is below a
e3ecefd6
MD
584 * certain threshold.
585 */
4c42f1b8 586 if (count < (1UL << COUNT_COMMIT_ORDER) * (split_count_mask + 1))
e3ecefd6 587 return;
4105056a 588 cds_lfht_resize_lazy_count(ht, size,
6ea6bc67 589 count >> (CHAIN_LEN_TARGET - 1));
df44348d
MD
590 }
591 }
592}
593
f9830efd 594static
4105056a 595void check_resize(struct cds_lfht *ht, unsigned long size, uint32_t chain_len)
f9830efd 596{
f8994aee
MD
597 unsigned long count;
598
b8af5011
MD
599 if (!(ht->flags & CDS_LFHT_AUTO_RESIZE))
600 return;
f8994aee
MD
601 count = uatomic_read(&ht->count);
602 /*
603 * Use bucket-local length for small table expand and for
604 * environments lacking per-cpu data support.
605 */
606 if (count >= (1UL << COUNT_COMMIT_ORDER))
607 return;
24365af7 608 if (chain_len > 100)
f0c29ed7 609 dbg_printf("WARNING: large chain length: %u.\n",
24365af7 610 chain_len);
3390d470 611 if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD)
ab65b890 612 cds_lfht_resize_lazy_grow(ht, size,
01370f0b 613 get_count_order_u32(chain_len - (CHAIN_LEN_TARGET - 1)));
f9830efd
MD
614}
615
abc490a1 616static
14044b37 617struct cds_lfht_node *clear_flag(struct cds_lfht_node *node)
abc490a1 618{
14044b37 619 return (struct cds_lfht_node *) (((unsigned long) node) & ~FLAGS_MASK);
abc490a1
MD
620}
621
622static
14044b37 623int is_removed(struct cds_lfht_node *node)
abc490a1 624{
d37166c6 625 return ((unsigned long) node) & REMOVED_FLAG;
abc490a1
MD
626}
627
628static
14044b37 629struct cds_lfht_node *flag_removed(struct cds_lfht_node *node)
abc490a1 630{
14044b37 631 return (struct cds_lfht_node *) (((unsigned long) node) | REMOVED_FLAG);
abc490a1
MD
632}
633
f5596c94 634static
1ee8f000 635int is_bucket(struct cds_lfht_node *node)
f5596c94 636{
1ee8f000 637 return ((unsigned long) node) & BUCKET_FLAG;
f5596c94
MD
638}
639
640static
1ee8f000 641struct cds_lfht_node *flag_bucket(struct cds_lfht_node *node)
f5596c94 642{
1ee8f000 643 return (struct cds_lfht_node *) (((unsigned long) node) | BUCKET_FLAG);
f5596c94 644}
bb7b2f26
MD
645
646static
647struct cds_lfht_node *get_end(void)
648{
649 return (struct cds_lfht_node *) END_VALUE;
650}
651
652static
653int is_end(struct cds_lfht_node *node)
654{
655 return clear_flag(node) == (struct cds_lfht_node *) END_VALUE;
656}
657
abc490a1 658static
ab65b890
LJ
659unsigned long _uatomic_xchg_monotonic_increase(unsigned long *ptr,
660 unsigned long v)
abc490a1
MD
661{
662 unsigned long old1, old2;
663
664 old1 = uatomic_read(ptr);
665 do {
666 old2 = old1;
667 if (old2 >= v)
f9830efd 668 return old2;
abc490a1 669 } while ((old1 = uatomic_cmpxchg(ptr, old2, v)) != old2);
ab65b890 670 return old2;
abc490a1
MD
671}
672
48f1b16d
LJ
673static
674void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order)
675{
0b6aa001 676 return ht->mm->alloc_bucket_table(ht, order);
48f1b16d
LJ
677}
678
679/*
680 * cds_lfht_free_bucket_table() should be called with decreasing order.
681 * When cds_lfht_free_bucket_table(0) is called, it means the whole
682 * lfht is destroyed.
683 */
684static
685void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order)
686{
0b6aa001 687 return ht->mm->free_bucket_table(ht, order);
48f1b16d
LJ
688}
689
9d72a73f
LJ
690static inline
691struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index)
f4a9cc0b 692{
0b6aa001 693 return ht->bucket_at(ht, index);
f4a9cc0b
LJ
694}
695
9d72a73f
LJ
696static inline
697struct cds_lfht_node *lookup_bucket(struct cds_lfht *ht, unsigned long size,
698 unsigned long hash)
699{
700 assert(size > 0);
701 return bucket_at(ht, hash & (size - 1));
702}
703
273399de
MD
704/*
705 * Remove all logically deleted nodes from a bucket up to a certain node key.
706 */
707static
1ee8f000 708void _cds_lfht_gc_bucket(struct cds_lfht_node *bucket, struct cds_lfht_node *node)
273399de 709{
14044b37 710 struct cds_lfht_node *iter_prev, *iter, *next, *new_next;
273399de 711
1ee8f000
LJ
712 assert(!is_bucket(bucket));
713 assert(!is_removed(bucket));
714 assert(!is_bucket(node));
c90201ac 715 assert(!is_removed(node));
273399de 716 for (;;) {
1ee8f000
LJ
717 iter_prev = bucket;
718 /* We can always skip the bucket node initially */
04db56f8 719 iter = rcu_dereference(iter_prev->next);
b4cb483f 720 assert(!is_removed(iter));
04db56f8 721 assert(iter_prev->reverse_hash <= node->reverse_hash);
bd4db153 722 /*
1ee8f000 723 * We should never be called with bucket (start of chain)
bd4db153
MD
724 * and logically removed node (end of path compression
725 * marker) being the actual same node. This would be a
726 * bug in the algorithm implementation.
727 */
1ee8f000 728 assert(bucket != node);
273399de 729 for (;;) {
8ed51e04 730 if (caa_unlikely(is_end(iter)))
f9c80341 731 return;
04db56f8 732 if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash))
f9c80341 733 return;
04db56f8 734 next = rcu_dereference(clear_flag(iter)->next);
8ed51e04 735 if (caa_likely(is_removed(next)))
273399de 736 break;
b453eae1 737 iter_prev = clear_flag(iter);
273399de
MD
738 iter = next;
739 }
b198f0fd 740 assert(!is_removed(iter));
1ee8f000
LJ
741 if (is_bucket(iter))
742 new_next = flag_bucket(clear_flag(next));
f5596c94
MD
743 else
744 new_next = clear_flag(next);
04db56f8 745 (void) uatomic_cmpxchg(&iter_prev->next, iter, new_next);
273399de 746 }
f9c80341 747 return;
273399de
MD
748}
749
9357c415
MD
750static
751int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
752 struct cds_lfht_node *old_node,
3fb86f26 753 struct cds_lfht_node *old_next,
9357c415
MD
754 struct cds_lfht_node *new_node)
755{
04db56f8 756 struct cds_lfht_node *bucket, *ret_next;
9357c415
MD
757
758 if (!old_node) /* Return -ENOENT if asked to replace NULL node */
7801dadd 759 return -ENOENT;
9357c415
MD
760
761 assert(!is_removed(old_node));
1ee8f000 762 assert(!is_bucket(old_node));
9357c415 763 assert(!is_removed(new_node));
1ee8f000 764 assert(!is_bucket(new_node));
9357c415 765 assert(new_node != old_node);
3fb86f26 766 for (;;) {
9357c415 767 /* Insert after node to be replaced */
9357c415
MD
768 if (is_removed(old_next)) {
769 /*
770 * Too late, the old node has been removed under us
771 * between lookup and replace. Fail.
772 */
7801dadd 773 return -ENOENT;
9357c415 774 }
1ee8f000 775 assert(!is_bucket(old_next));
9357c415 776 assert(new_node != clear_flag(old_next));
04db56f8 777 new_node->next = clear_flag(old_next);
9357c415
MD
778 /*
779 * Here is the whole trick for lock-free replace: we add
780 * the replacement node _after_ the node we want to
781 * replace by atomically setting its next pointer at the
782 * same time we set its removal flag. Given that
783 * the lookups/get next use an iterator aware of the
784 * next pointer, they will either skip the old node due
785 * to the removal flag and see the new node, or use
786 * the old node, but will not see the new one.
787 */
04db56f8 788 ret_next = uatomic_cmpxchg(&old_node->next,
9357c415 789 old_next, flag_removed(new_node));
3fb86f26 790 if (ret_next == old_next)
7801dadd 791 break; /* We performed the replacement. */
3fb86f26
LJ
792 old_next = ret_next;
793 }
9357c415 794
9357c415
MD
795 /*
796 * Ensure that the old node is not visible to readers anymore:
797 * lookup for the node, and remove it (along with any other
798 * logically removed node) if found.
799 */
04db56f8
LJ
800 bucket = lookup_bucket(ht, size, bit_reverse_ulong(old_node->reverse_hash));
801 _cds_lfht_gc_bucket(bucket, new_node);
7801dadd 802
04db56f8 803 assert(is_removed(rcu_dereference(old_node->next)));
7801dadd 804 return 0;
9357c415
MD
805}
806
83beee94
MD
807/*
808 * A non-NULL unique_ret pointer uses the "add unique" (or uniquify) add
809 * mode. A NULL unique_ret allows creation of duplicate keys.
810 */
abc490a1 811static
83beee94 812void _cds_lfht_add(struct cds_lfht *ht,
0422d92c 813 cds_lfht_match_fct match,
996ff57c 814 const void *key,
83beee94
MD
815 unsigned long size,
816 struct cds_lfht_node *node,
817 struct cds_lfht_iter *unique_ret,
1ee8f000 818 int bucket_flag)
abc490a1 819{
14044b37 820 struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next,
960c9e4f 821 *return_node;
04db56f8 822 struct cds_lfht_node *bucket;
abc490a1 823
1ee8f000 824 assert(!is_bucket(node));
c90201ac 825 assert(!is_removed(node));
04db56f8 826 bucket = lookup_bucket(ht, size, bit_reverse_ulong(node->reverse_hash));
abc490a1 827 for (;;) {
adc0de68 828 uint32_t chain_len = 0;
abc490a1 829
11519af6
MD
830 /*
831 * iter_prev points to the non-removed node prior to the
832 * insert location.
11519af6 833 */
04db56f8 834 iter_prev = bucket;
1ee8f000 835 /* We can always skip the bucket node initially */
04db56f8
LJ
836 iter = rcu_dereference(iter_prev->next);
837 assert(iter_prev->reverse_hash <= node->reverse_hash);
abc490a1 838 for (;;) {
8ed51e04 839 if (caa_unlikely(is_end(iter)))
273399de 840 goto insert;
04db56f8 841 if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash))
273399de 842 goto insert;
238cc06e 843
1ee8f000
LJ
844 /* bucket node is the first node of the identical-hash-value chain */
845 if (bucket_flag && clear_flag(iter)->reverse_hash == node->reverse_hash)
194fdbd1 846 goto insert;
238cc06e 847
04db56f8 848 next = rcu_dereference(clear_flag(iter)->next);
8ed51e04 849 if (caa_unlikely(is_removed(next)))
9dba85be 850 goto gc_node;
238cc06e
LJ
851
852 /* uniquely add */
83beee94 853 if (unique_ret
1ee8f000 854 && !is_bucket(next)
04db56f8 855 && clear_flag(iter)->reverse_hash == node->reverse_hash) {
238cc06e
LJ
856 struct cds_lfht_iter d_iter = { .node = node, .next = iter, };
857
858 /*
859 * uniquely adding inserts the node as the first
860 * node of the identical-hash-value node chain.
861 *
862 * This semantic ensures no duplicated keys
863 * should ever be observable in the table
864 * (including observe one node by one node
865 * by forward iterations)
866 */
04db56f8 867 cds_lfht_next_duplicate(ht, match, key, &d_iter);
238cc06e
LJ
868 if (!d_iter.node)
869 goto insert;
870
871 *unique_ret = d_iter;
83beee94 872 return;
48ed1c18 873 }
238cc06e 874
11519af6 875 /* Only account for identical reverse hash once */
04db56f8 876 if (iter_prev->reverse_hash != clear_flag(iter)->reverse_hash
1ee8f000 877 && !is_bucket(next))
4105056a 878 check_resize(ht, size, ++chain_len);
11519af6 879 iter_prev = clear_flag(iter);
273399de 880 iter = next;
abc490a1 881 }
48ed1c18 882
273399de 883 insert:
7ec59d3b 884 assert(node != clear_flag(iter));
11519af6 885 assert(!is_removed(iter_prev));
c90201ac 886 assert(!is_removed(iter));
f000907d 887 assert(iter_prev != node);
1ee8f000 888 if (!bucket_flag)
04db56f8 889 node->next = clear_flag(iter);
f9c80341 890 else
1ee8f000
LJ
891 node->next = flag_bucket(clear_flag(iter));
892 if (is_bucket(iter))
893 new_node = flag_bucket(node);
f5596c94
MD
894 else
895 new_node = node;
04db56f8 896 if (uatomic_cmpxchg(&iter_prev->next, iter,
48ed1c18 897 new_node) != iter) {
273399de 898 continue; /* retry */
48ed1c18 899 } else {
83beee94 900 return_node = node;
960c9e4f 901 goto end;
48ed1c18
MD
902 }
903
9dba85be
MD
904 gc_node:
905 assert(!is_removed(iter));
1ee8f000
LJ
906 if (is_bucket(iter))
907 new_next = flag_bucket(clear_flag(next));
f5596c94
MD
908 else
909 new_next = clear_flag(next);
04db56f8 910 (void) uatomic_cmpxchg(&iter_prev->next, iter, new_next);
273399de 911 /* retry */
464a1ec9 912 }
9357c415 913end:
83beee94
MD
914 if (unique_ret) {
915 unique_ret->node = return_node;
916 /* unique_ret->next left unset, never used. */
917 }
abc490a1 918}
464a1ec9 919
abc490a1 920static
860d07e8 921int _cds_lfht_del(struct cds_lfht *ht, unsigned long size,
4105056a 922 struct cds_lfht_node *node,
1ee8f000 923 int bucket_removal)
abc490a1 924{
04db56f8 925 struct cds_lfht_node *bucket, *next, *old;
5e28c532 926
9357c415 927 if (!node) /* Return -ENOENT if asked to delete NULL node */
743f9143 928 return -ENOENT;
9357c415 929
7ec59d3b 930 /* logically delete the node */
1ee8f000 931 assert(!is_bucket(node));
c90201ac 932 assert(!is_removed(node));
04db56f8 933 old = rcu_dereference(node->next);
7ec59d3b 934 do {
48ed1c18
MD
935 struct cds_lfht_node *new_next;
936
7ec59d3b 937 next = old;
8ed51e04 938 if (caa_unlikely(is_removed(next)))
743f9143 939 return -ENOENT;
1ee8f000
LJ
940 if (bucket_removal)
941 assert(is_bucket(next));
1475579c 942 else
1ee8f000 943 assert(!is_bucket(next));
48ed1c18 944 new_next = flag_removed(next);
04db56f8 945 old = uatomic_cmpxchg(&node->next, next, new_next);
7ec59d3b 946 } while (old != next);
7ec59d3b 947 /* We performed the (logical) deletion. */
7ec59d3b
MD
948
949 /*
950 * Ensure that the node is not visible to readers anymore: lookup for
273399de
MD
951 * the node, and remove it (along with any other logically removed node)
952 * if found.
11519af6 953 */
04db56f8
LJ
954 bucket = lookup_bucket(ht, size, bit_reverse_ulong(node->reverse_hash));
955 _cds_lfht_gc_bucket(bucket, node);
743f9143 956
04db56f8 957 assert(is_removed(rcu_dereference(node->next)));
743f9143 958 return 0;
abc490a1 959}
2ed95849 960
b7d619b0
MD
961static
962void *partition_resize_thread(void *arg)
963{
964 struct partition_resize_work *work = arg;
965
7b17c13e 966 work->ht->flavor->register_thread();
b7d619b0 967 work->fct(work->ht, work->i, work->start, work->len);
7b17c13e 968 work->ht->flavor->unregister_thread();
b7d619b0
MD
969 return NULL;
970}
971
972static
973void partition_resize_helper(struct cds_lfht *ht, unsigned long i,
974 unsigned long len,
975 void (*fct)(struct cds_lfht *ht, unsigned long i,
976 unsigned long start, unsigned long len))
977{
978 unsigned long partition_len;
979 struct partition_resize_work *work;
6083a889
MD
980 int thread, ret;
981 unsigned long nr_threads;
b7d619b0 982
6083a889
MD
983 /*
984 * Note: nr_cpus_mask + 1 is always power of 2.
985 * We spawn just the number of threads we need to satisfy the minimum
986 * partition size, up to the number of CPUs in the system.
987 */
91452a6a
MD
988 if (nr_cpus_mask > 0) {
989 nr_threads = min(nr_cpus_mask + 1,
990 len >> MIN_PARTITION_PER_THREAD_ORDER);
991 } else {
992 nr_threads = 1;
993 }
6083a889
MD
994 partition_len = len >> get_count_order_ulong(nr_threads);
995 work = calloc(nr_threads, sizeof(*work));
b7d619b0 996 assert(work);
6083a889
MD
997 for (thread = 0; thread < nr_threads; thread++) {
998 work[thread].ht = ht;
999 work[thread].i = i;
1000 work[thread].len = partition_len;
1001 work[thread].start = thread * partition_len;
1002 work[thread].fct = fct;
1af6e26e 1003 ret = pthread_create(&(work[thread].thread_id), ht->resize_attr,
6083a889 1004 partition_resize_thread, &work[thread]);
b7d619b0
MD
1005 assert(!ret);
1006 }
6083a889 1007 for (thread = 0; thread < nr_threads; thread++) {
1af6e26e 1008 ret = pthread_join(work[thread].thread_id, NULL);
b7d619b0
MD
1009 assert(!ret);
1010 }
1011 free(work);
b7d619b0
MD
1012}
1013
e8de508e
MD
1014/*
1015 * Holding RCU read lock to protect _cds_lfht_add against memory
1016 * reclaim that could be performed by other call_rcu worker threads (ABA
1017 * problem).
9ee0fc9a 1018 *
b7d619b0 1019 * When we reach a certain length, we can split this population phase over
9ee0fc9a
MD
1020 * many worker threads, based on the number of CPUs available in the system.
1021 * This should therefore take care of not having the expand lagging behind too
1022 * many concurrent insertion threads by using the scheduler's ability to
1ee8f000 1023 * schedule bucket node population fairly with insertions.
e8de508e 1024 */
4105056a 1025static
b7d619b0
MD
1026void init_table_populate_partition(struct cds_lfht *ht, unsigned long i,
1027 unsigned long start, unsigned long len)
4105056a 1028{
9d72a73f 1029 unsigned long j, size = 1UL << (i - 1);
4105056a 1030
d0d8f9aa 1031 assert(i > MIN_TABLE_ORDER);
7b17c13e 1032 ht->flavor->read_lock();
9d72a73f
LJ
1033 for (j = size + start; j < size + start + len; j++) {
1034 struct cds_lfht_node *new_node = bucket_at(ht, j);
1035
1036 assert(j >= size && j < (size << 1));
1037 dbg_printf("init populate: order %lu index %lu hash %lu\n",
1038 i, j, j);
1039 new_node->reverse_hash = bit_reverse_ulong(j);
1040 _cds_lfht_add(ht, NULL, NULL, size, new_node, NULL, 1);
4105056a 1041 }
7b17c13e 1042 ht->flavor->read_unlock();
b7d619b0
MD
1043}
1044
1045static
1046void init_table_populate(struct cds_lfht *ht, unsigned long i,
1047 unsigned long len)
1048{
1049 assert(nr_cpus_mask != -1);
6083a889 1050 if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) {
7b17c13e 1051 ht->flavor->thread_online();
b7d619b0 1052 init_table_populate_partition(ht, i, 0, len);
7b17c13e 1053 ht->flavor->thread_offline();
b7d619b0
MD
1054 return;
1055 }
1056 partition_resize_helper(ht, i, len, init_table_populate_partition);
4105056a
MD
1057}
1058
abc490a1 1059static
4105056a 1060void init_table(struct cds_lfht *ht,
93d46c39 1061 unsigned long first_order, unsigned long last_order)
24365af7 1062{
93d46c39 1063 unsigned long i;
24365af7 1064
93d46c39
LJ
1065 dbg_printf("init table: first_order %lu last_order %lu\n",
1066 first_order, last_order);
d0d8f9aa 1067 assert(first_order > MIN_TABLE_ORDER);
93d46c39 1068 for (i = first_order; i <= last_order; i++) {
4105056a 1069 unsigned long len;
24365af7 1070
4f6e90b7 1071 len = 1UL << (i - 1);
f0c29ed7 1072 dbg_printf("init order %lu len: %lu\n", i, len);
4d676753
MD
1073
1074 /* Stop expand if the resize target changes under us */
7b3893e4 1075 if (CMM_LOAD_SHARED(ht->resize_target) < (1UL << i))
4d676753
MD
1076 break;
1077
48f1b16d 1078 cds_lfht_alloc_bucket_table(ht, i);
4105056a 1079
4105056a 1080 /*
1ee8f000
LJ
1081 * Set all bucket nodes reverse hash values for a level and
1082 * link all bucket nodes into the table.
4105056a 1083 */
dc1da8f6 1084 init_table_populate(ht, i, len);
4105056a 1085
f9c80341
MD
1086 /*
1087 * Update table size.
1088 */
1089 cmm_smp_wmb(); /* populate data before RCU size */
7b3893e4 1090 CMM_STORE_SHARED(ht->size, 1UL << i);
f9c80341 1091
4f6e90b7 1092 dbg_printf("init new size: %lu\n", 1UL << i);
4105056a
MD
1093 if (CMM_LOAD_SHARED(ht->in_progress_destroy))
1094 break;
1095 }
1096}
1097
e8de508e
MD
1098/*
1099 * Holding RCU read lock to protect _cds_lfht_remove against memory
1100 * reclaim that could be performed by other call_rcu worker threads (ABA
1101 * problem).
1102 * For a single level, we logically remove and garbage collect each node.
1103 *
1104 * As a design choice, we perform logical removal and garbage collection on a
1105 * node-per-node basis to simplify this algorithm. We also assume keeping good
1106 * cache locality of the operation would overweight possible performance gain
1107 * that could be achieved by batching garbage collection for multiple levels.
1108 * However, this would have to be justified by benchmarks.
1109 *
1110 * Concurrent removal and add operations are helping us perform garbage
1111 * collection of logically removed nodes. We guarantee that all logically
1112 * removed nodes have been garbage-collected (unlinked) before call_rcu is
1ee8f000 1113 * invoked to free a hole level of bucket nodes (after a grace period).
e8de508e
MD
1114 *
1115 * Logical removal and garbage collection can therefore be done in batch or on a
1116 * node-per-node basis, as long as the guarantee above holds.
9ee0fc9a 1117 *
b7d619b0
MD
1118 * When we reach a certain length, we can split this removal over many worker
1119 * threads, based on the number of CPUs available in the system. This should
1120 * take care of not letting resize process lag behind too many concurrent
9ee0fc9a 1121 * updater threads actively inserting into the hash table.
e8de508e 1122 */
4105056a 1123static
b7d619b0
MD
1124void remove_table_partition(struct cds_lfht *ht, unsigned long i,
1125 unsigned long start, unsigned long len)
4105056a 1126{
9d72a73f 1127 unsigned long j, size = 1UL << (i - 1);
4105056a 1128
d0d8f9aa 1129 assert(i > MIN_TABLE_ORDER);
7b17c13e 1130 ht->flavor->read_lock();
9d72a73f
LJ
1131 for (j = size + start; j < size + start + len; j++) {
1132 struct cds_lfht_node *fini_node = bucket_at(ht, j);
1133
1134 assert(j >= size && j < (size << 1));
1135 dbg_printf("remove entry: order %lu index %lu hash %lu\n",
1136 i, j, j);
1137 fini_node->reverse_hash = bit_reverse_ulong(j);
1138 (void) _cds_lfht_del(ht, size, fini_node, 1);
abc490a1 1139 }
7b17c13e 1140 ht->flavor->read_unlock();
b7d619b0
MD
1141}
1142
1143static
1144void remove_table(struct cds_lfht *ht, unsigned long i, unsigned long len)
1145{
1146
1147 assert(nr_cpus_mask != -1);
6083a889 1148 if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) {
7b17c13e 1149 ht->flavor->thread_online();
b7d619b0 1150 remove_table_partition(ht, i, 0, len);
7b17c13e 1151 ht->flavor->thread_offline();
b7d619b0
MD
1152 return;
1153 }
1154 partition_resize_helper(ht, i, len, remove_table_partition);
2ed95849
MD
1155}
1156
1475579c 1157static
4105056a 1158void fini_table(struct cds_lfht *ht,
93d46c39 1159 unsigned long first_order, unsigned long last_order)
1475579c 1160{
93d46c39 1161 long i;
48f1b16d 1162 unsigned long free_by_rcu_order = 0;
1475579c 1163
93d46c39
LJ
1164 dbg_printf("fini table: first_order %lu last_order %lu\n",
1165 first_order, last_order);
d0d8f9aa 1166 assert(first_order > MIN_TABLE_ORDER);
93d46c39 1167 for (i = last_order; i >= first_order; i--) {
4105056a 1168 unsigned long len;
1475579c 1169
4f6e90b7 1170 len = 1UL << (i - 1);
1475579c 1171 dbg_printf("fini order %lu len: %lu\n", i, len);
4105056a 1172
4d676753 1173 /* Stop shrink if the resize target changes under us */
7b3893e4 1174 if (CMM_LOAD_SHARED(ht->resize_target) > (1UL << (i - 1)))
4d676753
MD
1175 break;
1176
1177 cmm_smp_wmb(); /* populate data before RCU size */
7b3893e4 1178 CMM_STORE_SHARED(ht->size, 1UL << (i - 1));
4d676753
MD
1179
1180 /*
1181 * We need to wait for all add operations to reach Q.S. (and
1182 * thus use the new table for lookups) before we can start
1ee8f000 1183 * releasing the old bucket nodes. Otherwise their lookup will
4d676753
MD
1184 * return a logically removed node as insert position.
1185 */
7b17c13e 1186 ht->flavor->update_synchronize_rcu();
48f1b16d
LJ
1187 if (free_by_rcu_order)
1188 cds_lfht_free_bucket_table(ht, free_by_rcu_order);
4d676753 1189
21263e21 1190 /*
1ee8f000
LJ
1191 * Set "removed" flag in bucket nodes about to be removed.
1192 * Unlink all now-logically-removed bucket node pointers.
4105056a
MD
1193 * Concurrent add/remove operation are helping us doing
1194 * the gc.
21263e21 1195 */
4105056a
MD
1196 remove_table(ht, i, len);
1197
48f1b16d 1198 free_by_rcu_order = i;
4105056a
MD
1199
1200 dbg_printf("fini new size: %lu\n", 1UL << i);
1475579c
MD
1201 if (CMM_LOAD_SHARED(ht->in_progress_destroy))
1202 break;
1203 }
0d14ceb2 1204
48f1b16d 1205 if (free_by_rcu_order) {
7b17c13e 1206 ht->flavor->update_synchronize_rcu();
48f1b16d 1207 cds_lfht_free_bucket_table(ht, free_by_rcu_order);
0d14ceb2 1208 }
1475579c
MD
1209}
1210
ff0d69de 1211static
1ee8f000 1212void cds_lfht_create_bucket(struct cds_lfht *ht, unsigned long size)
ff0d69de 1213{
04db56f8 1214 struct cds_lfht_node *prev, *node;
9d72a73f 1215 unsigned long order, len, i;
ff0d69de 1216
48f1b16d 1217 cds_lfht_alloc_bucket_table(ht, 0);
ff0d69de 1218
9d72a73f
LJ
1219 dbg_printf("create bucket: order 0 index 0 hash 0\n");
1220 node = bucket_at(ht, 0);
1221 node->next = flag_bucket(get_end());
1222 node->reverse_hash = 0;
ff0d69de
LJ
1223
1224 for (order = 1; order < get_count_order_ulong(size) + 1; order++) {
1225 len = 1UL << (order - 1);
48f1b16d 1226 cds_lfht_alloc_bucket_table(ht, order);
ff0d69de 1227
9d72a73f
LJ
1228 for (i = 0; i < len; i++) {
1229 /*
1230 * Now, we are trying to init the node with the
1231 * hash=(len+i) (which is also a bucket with the
1232 * index=(len+i)) and insert it into the hash table,
1233 * so this node has to be inserted after the bucket
1234 * with the index=(len+i)&(len-1)=i. And because there
1235 * is no other non-bucket node nor bucket node with
1236 * larger index/hash inserted, so the bucket node
1237 * being inserted should be inserted directly linked
1238 * after the bucket node with index=i.
1239 */
1240 prev = bucket_at(ht, i);
1241 node = bucket_at(ht, len + i);
ff0d69de 1242
1ee8f000 1243 dbg_printf("create bucket: order %lu index %lu hash %lu\n",
9d72a73f
LJ
1244 order, len + i, len + i);
1245 node->reverse_hash = bit_reverse_ulong(len + i);
1246
1247 /* insert after prev */
1248 assert(is_bucket(prev->next));
ff0d69de 1249 node->next = prev->next;
1ee8f000 1250 prev->next = flag_bucket(node);
ff0d69de
LJ
1251 }
1252 }
1253}
1254
0422d92c 1255struct cds_lfht *_cds_lfht_new(unsigned long init_size,
0722081a 1256 unsigned long min_nr_alloc_buckets,
747d725c 1257 unsigned long max_nr_buckets,
b8af5011 1258 int flags,
0b6aa001 1259 const struct cds_lfht_mm_type *mm,
7b17c13e 1260 const struct rcu_flavor_struct *flavor,
b7d619b0 1261 pthread_attr_t *attr)
abc490a1 1262{
14044b37 1263 struct cds_lfht *ht;
24365af7 1264 unsigned long order;
abc490a1 1265
0722081a
LJ
1266 /* min_nr_alloc_buckets must be power of two */
1267 if (!min_nr_alloc_buckets || (min_nr_alloc_buckets & (min_nr_alloc_buckets - 1)))
5488222b 1268 return NULL;
747d725c 1269
8129be4e 1270 /* init_size must be power of two */
5488222b 1271 if (!init_size || (init_size & (init_size - 1)))
8129be4e 1272 return NULL;
747d725c 1273
0b6aa001
LJ
1274 /* max_nr_buckets == 0 for order based mm means infinite */
1275 if (mm == &cds_lfht_mm_order && !max_nr_buckets)
747d725c
LJ
1276 max_nr_buckets = 1UL << (MAX_TABLE_ORDER - 1);
1277
1278 /* max_nr_buckets must be power of two */
1279 if (!max_nr_buckets || (max_nr_buckets & (max_nr_buckets - 1)))
1280 return NULL;
1281
0722081a 1282 min_nr_alloc_buckets = max(min_nr_alloc_buckets, MIN_TABLE_SIZE);
d0d8f9aa 1283 init_size = max(init_size, MIN_TABLE_SIZE);
747d725c
LJ
1284 max_nr_buckets = max(max_nr_buckets, min_nr_alloc_buckets);
1285 init_size = min(init_size, max_nr_buckets);
0b6aa001
LJ
1286
1287 ht = mm->alloc_cds_lfht(min_nr_alloc_buckets, max_nr_buckets);
b7d619b0 1288 assert(ht);
0b6aa001
LJ
1289 assert(ht->mm == mm);
1290 assert(ht->bucket_at == mm->bucket_at);
1291
b5d6b20f 1292 ht->flags = flags;
7b17c13e 1293 ht->flavor = flavor;
b7d619b0 1294 ht->resize_attr = attr;
5afadd12 1295 alloc_split_items_count(ht);
abc490a1
MD
1296 /* this mutex should not nest in read-side C.S. */
1297 pthread_mutex_init(&ht->resize_mutex, NULL);
5488222b 1298 order = get_count_order_ulong(init_size);
7b3893e4 1299 ht->resize_target = 1UL << order;
1ee8f000 1300 cds_lfht_create_bucket(ht, 1UL << order);
7b3893e4 1301 ht->size = 1UL << order;
abc490a1
MD
1302 return ht;
1303}
1304
6f554439 1305void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
996ff57c 1306 cds_lfht_match_fct match, const void *key,
6f554439 1307 struct cds_lfht_iter *iter)
2ed95849 1308{
04db56f8 1309 struct cds_lfht_node *node, *next, *bucket;
0422d92c 1310 unsigned long reverse_hash, size;
2ed95849 1311
abc490a1 1312 reverse_hash = bit_reverse_ulong(hash);
464a1ec9 1313
7b3893e4 1314 size = rcu_dereference(ht->size);
04db56f8 1315 bucket = lookup_bucket(ht, size, hash);
1ee8f000 1316 /* We can always skip the bucket node initially */
04db56f8 1317 node = rcu_dereference(bucket->next);
bb7b2f26 1318 node = clear_flag(node);
2ed95849 1319 for (;;) {
8ed51e04 1320 if (caa_unlikely(is_end(node))) {
96ad1112 1321 node = next = NULL;
abc490a1 1322 break;
bb7b2f26 1323 }
04db56f8 1324 if (caa_unlikely(node->reverse_hash > reverse_hash)) {
96ad1112 1325 node = next = NULL;
abc490a1 1326 break;
2ed95849 1327 }
04db56f8 1328 next = rcu_dereference(node->next);
7f52427b 1329 assert(node == clear_flag(node));
8ed51e04 1330 if (caa_likely(!is_removed(next))
1ee8f000 1331 && !is_bucket(next)
04db56f8 1332 && node->reverse_hash == reverse_hash
0422d92c 1333 && caa_likely(match(node, key))) {
273399de 1334 break;
2ed95849 1335 }
1b81fe1a 1336 node = clear_flag(next);
2ed95849 1337 }
1ee8f000 1338 assert(!node || !is_bucket(rcu_dereference(node->next)));
adc0de68
MD
1339 iter->node = node;
1340 iter->next = next;
abc490a1 1341}
e0ba718a 1342
0422d92c 1343void cds_lfht_next_duplicate(struct cds_lfht *ht, cds_lfht_match_fct match,
996ff57c 1344 const void *key, struct cds_lfht_iter *iter)
a481e5ff 1345{
adc0de68 1346 struct cds_lfht_node *node, *next;
a481e5ff 1347 unsigned long reverse_hash;
a481e5ff 1348
adc0de68 1349 node = iter->node;
04db56f8 1350 reverse_hash = node->reverse_hash;
adc0de68 1351 next = iter->next;
a481e5ff
MD
1352 node = clear_flag(next);
1353
1354 for (;;) {
8ed51e04 1355 if (caa_unlikely(is_end(node))) {
96ad1112 1356 node = next = NULL;
a481e5ff 1357 break;
bb7b2f26 1358 }
04db56f8 1359 if (caa_unlikely(node->reverse_hash > reverse_hash)) {
96ad1112 1360 node = next = NULL;
a481e5ff
MD
1361 break;
1362 }
04db56f8 1363 next = rcu_dereference(node->next);
8ed51e04 1364 if (caa_likely(!is_removed(next))
1ee8f000 1365 && !is_bucket(next)
04db56f8 1366 && caa_likely(match(node, key))) {
a481e5ff
MD
1367 break;
1368 }
1369 node = clear_flag(next);
1370 }
1ee8f000 1371 assert(!node || !is_bucket(rcu_dereference(node->next)));
adc0de68
MD
1372 iter->node = node;
1373 iter->next = next;
a481e5ff
MD
1374}
1375
4e9b9fbf
MD
1376void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter)
1377{
1378 struct cds_lfht_node *node, *next;
1379
853395e1 1380 node = clear_flag(iter->next);
4e9b9fbf 1381 for (;;) {
8ed51e04 1382 if (caa_unlikely(is_end(node))) {
4e9b9fbf
MD
1383 node = next = NULL;
1384 break;
1385 }
04db56f8 1386 next = rcu_dereference(node->next);
8ed51e04 1387 if (caa_likely(!is_removed(next))
1ee8f000 1388 && !is_bucket(next)) {
4e9b9fbf
MD
1389 break;
1390 }
1391 node = clear_flag(next);
1392 }
1ee8f000 1393 assert(!node || !is_bucket(rcu_dereference(node->next)));
4e9b9fbf
MD
1394 iter->node = node;
1395 iter->next = next;
1396}
1397
1398void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter)
1399{
4e9b9fbf 1400 /*
1ee8f000 1401 * Get next after first bucket node. The first bucket node is the
4e9b9fbf
MD
1402 * first node of the linked list.
1403 */
9d72a73f 1404 iter->next = bucket_at(ht, 0)->next;
4e9b9fbf
MD
1405 cds_lfht_next(ht, iter);
1406}
1407
0422d92c
MD
1408void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
1409 struct cds_lfht_node *node)
abc490a1 1410{
0422d92c 1411 unsigned long size;
ab7d5fc6 1412
04db56f8 1413 node->reverse_hash = bit_reverse_ulong((unsigned long) hash);
7b3893e4 1414 size = rcu_dereference(ht->size);
04db56f8 1415 _cds_lfht_add(ht, NULL, NULL, size, node, NULL, 0);
14360f1c 1416 ht_count_add(ht, size, hash);
3eca1b8c
MD
1417}
1418
14044b37 1419struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
6f554439 1420 unsigned long hash,
0422d92c 1421 cds_lfht_match_fct match,
996ff57c 1422 const void *key,
48ed1c18 1423 struct cds_lfht_node *node)
3eca1b8c 1424{
0422d92c 1425 unsigned long size;
83beee94 1426 struct cds_lfht_iter iter;
3eca1b8c 1427
04db56f8 1428 node->reverse_hash = bit_reverse_ulong((unsigned long) hash);
7b3893e4 1429 size = rcu_dereference(ht->size);
04db56f8 1430 _cds_lfht_add(ht, match, key, size, node, &iter, 0);
83beee94 1431 if (iter.node == node)
14360f1c 1432 ht_count_add(ht, size, hash);
83beee94 1433 return iter.node;
2ed95849
MD
1434}
1435
9357c415 1436struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
6f554439 1437 unsigned long hash,
0422d92c 1438 cds_lfht_match_fct match,
996ff57c 1439 const void *key,
48ed1c18
MD
1440 struct cds_lfht_node *node)
1441{
0422d92c 1442 unsigned long size;
83beee94 1443 struct cds_lfht_iter iter;
48ed1c18 1444
04db56f8 1445 node->reverse_hash = bit_reverse_ulong((unsigned long) hash);
7b3893e4 1446 size = rcu_dereference(ht->size);
83beee94 1447 for (;;) {
04db56f8 1448 _cds_lfht_add(ht, match, key, size, node, &iter, 0);
83beee94 1449 if (iter.node == node) {
14360f1c 1450 ht_count_add(ht, size, hash);
83beee94
MD
1451 return NULL;
1452 }
1453
1454 if (!_cds_lfht_replace(ht, size, iter.node, iter.next, node))
1455 return iter.node;
1456 }
48ed1c18
MD
1457}
1458
9357c415
MD
1459int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter,
1460 struct cds_lfht_node *new_node)
1461{
1462 unsigned long size;
1463
7b3893e4 1464 size = rcu_dereference(ht->size);
9357c415
MD
1465 return _cds_lfht_replace(ht, size, old_iter->node, old_iter->next,
1466 new_node);
1467}
1468
1469int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_iter *iter)
2ed95849 1470{
14360f1c 1471 unsigned long size, hash;
df44348d 1472 int ret;
abc490a1 1473
7b3893e4 1474 size = rcu_dereference(ht->size);
9357c415 1475 ret = _cds_lfht_del(ht, size, iter->node, 0);
14360f1c 1476 if (!ret) {
04db56f8 1477 hash = bit_reverse_ulong(iter->node->reverse_hash);
14360f1c
LJ
1478 ht_count_del(ht, size, hash);
1479 }
df44348d 1480 return ret;
2ed95849 1481}
ab7d5fc6 1482
abc490a1 1483static
1ee8f000 1484int cds_lfht_delete_bucket(struct cds_lfht *ht)
674f7a69 1485{
14044b37 1486 struct cds_lfht_node *node;
4105056a 1487 unsigned long order, i, size;
674f7a69 1488
abc490a1 1489 /* Check that the table is empty */
9d72a73f 1490 node = bucket_at(ht, 0);
abc490a1 1491 do {
04db56f8 1492 node = clear_flag(node)->next;
1ee8f000 1493 if (!is_bucket(node))
abc490a1 1494 return -EPERM;
273399de 1495 assert(!is_removed(node));
bb7b2f26 1496 } while (!is_end(node));
4105056a
MD
1497 /*
1498 * size accessed without rcu_dereference because hash table is
1499 * being destroyed.
1500 */
7b3893e4 1501 size = ht->size;
1ee8f000 1502 /* Internal sanity check: all nodes left should be bucket */
48f1b16d
LJ
1503 for (i = 0; i < size; i++) {
1504 node = bucket_at(ht, i);
1505 dbg_printf("delete bucket: index %lu expected hash %lu hash %lu\n",
1506 i, i, bit_reverse_ulong(node->reverse_hash));
1507 assert(is_bucket(node->next));
1508 }
24365af7 1509
48f1b16d
LJ
1510 for (order = get_count_order_ulong(size); (long)order >= 0; order--)
1511 cds_lfht_free_bucket_table(ht, order);
5488222b 1512
abc490a1 1513 return 0;
674f7a69
MD
1514}
1515
1516/*
1517 * Should only be called when no more concurrent readers nor writers can
1518 * possibly access the table.
1519 */
b7d619b0 1520int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr)
674f7a69 1521{
5e28c532
MD
1522 int ret;
1523
848d4088 1524 /* Wait for in-flight resize operations to complete */
24953e08
MD
1525 _CMM_STORE_SHARED(ht->in_progress_destroy, 1);
1526 cmm_smp_mb(); /* Store destroy before load resize */
848d4088
MD
1527 while (uatomic_read(&ht->in_progress_resize))
1528 poll(NULL, 0, 100); /* wait for 100ms */
1ee8f000 1529 ret = cds_lfht_delete_bucket(ht);
abc490a1
MD
1530 if (ret)
1531 return ret;
5afadd12 1532 free_split_items_count(ht);
b7d619b0
MD
1533 if (attr)
1534 *attr = ht->resize_attr;
98808fb1 1535 poison_free(ht);
5e28c532 1536 return ret;
674f7a69
MD
1537}
1538
14044b37 1539void cds_lfht_count_nodes(struct cds_lfht *ht,
d933dd0e 1540 long *approx_before,
273399de 1541 unsigned long *count,
973e5e1b 1542 unsigned long *removed,
d933dd0e 1543 long *approx_after)
273399de 1544{
14044b37 1545 struct cds_lfht_node *node, *next;
1ee8f000 1546 unsigned long nr_bucket = 0;
273399de 1547
7ed7682f 1548 *approx_before = 0;
5afadd12 1549 if (ht->split_count) {
973e5e1b
MD
1550 int i;
1551
4c42f1b8
LJ
1552 for (i = 0; i < split_count_mask + 1; i++) {
1553 *approx_before += uatomic_read(&ht->split_count[i].add);
1554 *approx_before -= uatomic_read(&ht->split_count[i].del);
973e5e1b
MD
1555 }
1556 }
1557
273399de
MD
1558 *count = 0;
1559 *removed = 0;
1560
1ee8f000 1561 /* Count non-bucket nodes in the table */
9d72a73f 1562 node = bucket_at(ht, 0);
273399de 1563 do {
04db56f8 1564 next = rcu_dereference(node->next);
b198f0fd 1565 if (is_removed(next)) {
1ee8f000 1566 if (!is_bucket(next))
973e5e1b
MD
1567 (*removed)++;
1568 else
1ee8f000
LJ
1569 (nr_bucket)++;
1570 } else if (!is_bucket(next))
273399de 1571 (*count)++;
24365af7 1572 else
1ee8f000 1573 (nr_bucket)++;
273399de 1574 node = clear_flag(next);
bb7b2f26 1575 } while (!is_end(node));
1ee8f000 1576 dbg_printf("number of bucket nodes: %lu\n", nr_bucket);
7ed7682f 1577 *approx_after = 0;
5afadd12 1578 if (ht->split_count) {
973e5e1b
MD
1579 int i;
1580
4c42f1b8
LJ
1581 for (i = 0; i < split_count_mask + 1; i++) {
1582 *approx_after += uatomic_read(&ht->split_count[i].add);
1583 *approx_after -= uatomic_read(&ht->split_count[i].del);
973e5e1b
MD
1584 }
1585 }
273399de
MD
1586}
1587
1475579c 1588/* called with resize mutex held */
abc490a1 1589static
4105056a 1590void _do_cds_lfht_grow(struct cds_lfht *ht,
1475579c 1591 unsigned long old_size, unsigned long new_size)
abc490a1 1592{
1475579c 1593 unsigned long old_order, new_order;
1475579c 1594
93d46c39
LJ
1595 old_order = get_count_order_ulong(old_size);
1596 new_order = get_count_order_ulong(new_size);
1a401918
LJ
1597 dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
1598 old_size, old_order, new_size, new_order);
1475579c 1599 assert(new_size > old_size);
93d46c39 1600 init_table(ht, old_order + 1, new_order);
abc490a1
MD
1601}
1602
1603/* called with resize mutex held */
1604static
4105056a 1605void _do_cds_lfht_shrink(struct cds_lfht *ht,
1475579c 1606 unsigned long old_size, unsigned long new_size)
464a1ec9 1607{
1475579c 1608 unsigned long old_order, new_order;
464a1ec9 1609
d0d8f9aa 1610 new_size = max(new_size, MIN_TABLE_SIZE);
93d46c39
LJ
1611 old_order = get_count_order_ulong(old_size);
1612 new_order = get_count_order_ulong(new_size);
1a401918
LJ
1613 dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
1614 old_size, old_order, new_size, new_order);
1475579c 1615 assert(new_size < old_size);
1475579c 1616
1ee8f000 1617 /* Remove and unlink all bucket nodes to remove. */
93d46c39 1618 fini_table(ht, new_order + 1, old_order);
464a1ec9
MD
1619}
1620
1475579c
MD
1621
1622/* called with resize mutex held */
1623static
1624void _do_cds_lfht_resize(struct cds_lfht *ht)
1625{
1626 unsigned long new_size, old_size;
4105056a
MD
1627
1628 /*
1629 * Resize table, re-do if the target size has changed under us.
1630 */
1631 do {
d2be3620
MD
1632 assert(uatomic_read(&ht->in_progress_resize));
1633 if (CMM_LOAD_SHARED(ht->in_progress_destroy))
1634 break;
7b3893e4
LJ
1635 ht->resize_initiated = 1;
1636 old_size = ht->size;
1637 new_size = CMM_LOAD_SHARED(ht->resize_target);
4105056a
MD
1638 if (old_size < new_size)
1639 _do_cds_lfht_grow(ht, old_size, new_size);
1640 else if (old_size > new_size)
1641 _do_cds_lfht_shrink(ht, old_size, new_size);
7b3893e4 1642 ht->resize_initiated = 0;
4105056a
MD
1643 /* write resize_initiated before read resize_target */
1644 cmm_smp_mb();
7b3893e4 1645 } while (ht->size != CMM_LOAD_SHARED(ht->resize_target));
1475579c
MD
1646}
1647
abc490a1 1648static
ab65b890 1649unsigned long resize_target_grow(struct cds_lfht *ht, unsigned long new_size)
464a1ec9 1650{
7b3893e4 1651 return _uatomic_xchg_monotonic_increase(&ht->resize_target, new_size);
464a1ec9
MD
1652}
1653
1475579c 1654static
4105056a 1655void resize_target_update_count(struct cds_lfht *ht,
b8af5011 1656 unsigned long count)
1475579c 1657{
d0d8f9aa 1658 count = max(count, MIN_TABLE_SIZE);
747d725c 1659 count = min(count, ht->max_nr_buckets);
7b3893e4 1660 uatomic_set(&ht->resize_target, count);
1475579c
MD
1661}
1662
1663void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size)
464a1ec9 1664{
4105056a 1665 resize_target_update_count(ht, new_size);
7b3893e4 1666 CMM_STORE_SHARED(ht->resize_initiated, 1);
7b17c13e 1667 ht->flavor->thread_offline();
1475579c
MD
1668 pthread_mutex_lock(&ht->resize_mutex);
1669 _do_cds_lfht_resize(ht);
1670 pthread_mutex_unlock(&ht->resize_mutex);
7b17c13e 1671 ht->flavor->thread_online();
abc490a1 1672}
464a1ec9 1673
abc490a1
MD
1674static
1675void do_resize_cb(struct rcu_head *head)
1676{
1677 struct rcu_resize_work *work =
1678 caa_container_of(head, struct rcu_resize_work, head);
14044b37 1679 struct cds_lfht *ht = work->ht;
abc490a1 1680
7b17c13e 1681 ht->flavor->thread_offline();
abc490a1 1682 pthread_mutex_lock(&ht->resize_mutex);
14044b37 1683 _do_cds_lfht_resize(ht);
abc490a1 1684 pthread_mutex_unlock(&ht->resize_mutex);
7b17c13e 1685 ht->flavor->thread_online();
98808fb1 1686 poison_free(work);
848d4088
MD
1687 cmm_smp_mb(); /* finish resize before decrement */
1688 uatomic_dec(&ht->in_progress_resize);
464a1ec9
MD
1689}
1690
abc490a1 1691static
f1f119ee 1692void __cds_lfht_resize_lazy_launch(struct cds_lfht *ht)
ab7d5fc6 1693{
abc490a1
MD
1694 struct rcu_resize_work *work;
1695
4105056a
MD
1696 /* Store resize_target before read resize_initiated */
1697 cmm_smp_mb();
7b3893e4 1698 if (!CMM_LOAD_SHARED(ht->resize_initiated)) {
848d4088 1699 uatomic_inc(&ht->in_progress_resize);
59290e9d 1700 cmm_smp_mb(); /* increment resize count before load destroy */
ed35e6d8
MD
1701 if (CMM_LOAD_SHARED(ht->in_progress_destroy)) {
1702 uatomic_dec(&ht->in_progress_resize);
59290e9d 1703 return;
ed35e6d8 1704 }
f9830efd
MD
1705 work = malloc(sizeof(*work));
1706 work->ht = ht;
7b17c13e 1707 ht->flavor->update_call_rcu(&work->head, do_resize_cb);
7b3893e4 1708 CMM_STORE_SHARED(ht->resize_initiated, 1);
f9830efd 1709 }
ab7d5fc6 1710}
3171717f 1711
f1f119ee
LJ
1712static
1713void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth)
1714{
1715 unsigned long target_size = size << growth;
1716
747d725c 1717 target_size = min(target_size, ht->max_nr_buckets);
f1f119ee
LJ
1718 if (resize_target_grow(ht, target_size) >= target_size)
1719 return;
1720
1721 __cds_lfht_resize_lazy_launch(ht);
1722}
1723
89bb121d
LJ
1724/*
1725 * We favor grow operations over shrink. A shrink operation never occurs
1726 * if a grow operation is queued for lazy execution. A grow operation
1727 * cancels any pending shrink lazy execution.
1728 */
3171717f 1729static
4105056a 1730void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
3171717f
MD
1731 unsigned long count)
1732{
b8af5011
MD
1733 if (!(ht->flags & CDS_LFHT_AUTO_RESIZE))
1734 return;
d0d8f9aa 1735 count = max(count, MIN_TABLE_SIZE);
747d725c 1736 count = min(count, ht->max_nr_buckets);
89bb121d
LJ
1737 if (count == size)
1738 return; /* Already the right size, no resize needed */
1739 if (count > size) { /* lazy grow */
1740 if (resize_target_grow(ht, count) >= count)
1741 return;
1742 } else { /* lazy shrink */
1743 for (;;) {
1744 unsigned long s;
1745
7b3893e4 1746 s = uatomic_cmpxchg(&ht->resize_target, size, count);
89bb121d
LJ
1747 if (s == size)
1748 break; /* no resize needed */
1749 if (s > size)
1750 return; /* growing is/(was just) in progress */
1751 if (s <= count)
1752 return; /* some other thread do shrink */
1753 size = s;
1754 }
1755 }
f1f119ee 1756 __cds_lfht_resize_lazy_launch(ht);
3171717f 1757}
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