| 1 | /* |
| 2 | * rculfhash.c |
| 3 | * |
| 4 | * Userspace RCU library - Lock-Free Resizable RCU Hash Table |
| 5 | * |
| 6 | * Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 7 | * |
| 8 | * This library is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU Lesser General Public |
| 10 | * License as published by the Free Software Foundation; either |
| 11 | * version 2.1 of the License, or (at your option) any later version. |
| 12 | * |
| 13 | * This library is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 16 | * Lesser General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU Lesser General Public |
| 19 | * License along with this library; if not, write to the Free Software |
| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 21 | */ |
| 22 | |
| 23 | /* |
| 24 | * Based on the following articles: |
| 25 | * - Ori Shalev and Nir Shavit. Split-ordered lists: Lock-free |
| 26 | * extensible hash tables. J. ACM 53, 3 (May 2006), 379-405. |
| 27 | * - Michael, M. M. High performance dynamic lock-free hash tables |
| 28 | * and list-based sets. In Proceedings of the fourteenth annual ACM |
| 29 | * symposium on Parallel algorithms and architectures, ACM Press, |
| 30 | * (2002), 73-82. |
| 31 | * |
| 32 | * Some specificities of this Lock-Free Resizable RCU Hash Table |
| 33 | * implementation: |
| 34 | * |
| 35 | * - RCU read-side critical section allows readers to perform hash |
| 36 | * table lookups and use the returned objects safely by delaying |
| 37 | * memory reclaim of a grace period. |
| 38 | * - Add and remove operations are lock-free, and do not need to |
| 39 | * allocate memory. They need to be executed within RCU read-side |
| 40 | * critical section to ensure the objects they read are valid and to |
| 41 | * deal with the cmpxchg ABA problem. |
| 42 | * - add and add_unique operations are supported. add_unique checks if |
| 43 | * the node key already exists in the hash table. It ensures no key |
| 44 | * duplicata exists. |
| 45 | * - The resize operation executes concurrently with add/remove/lookup. |
| 46 | * - Hash table nodes are contained within a split-ordered list. This |
| 47 | * list is ordered by incrementing reversed-bits-hash value. |
| 48 | * - An index of bucket nodes is kept. These bucket nodes are the hash |
| 49 | * table "buckets", and they are also chained together in the |
| 50 | * split-ordered list, which allows recursive expansion. |
| 51 | * - The resize operation for small tables only allows expanding the hash table. |
| 52 | * It is triggered automatically by detecting long chains in the add |
| 53 | * operation. |
| 54 | * - The resize operation for larger tables (and available through an |
| 55 | * API) allows both expanding and shrinking the hash table. |
| 56 | * - Split-counters are used to keep track of the number of |
| 57 | * nodes within the hash table for automatic resize triggering. |
| 58 | * - Resize operation initiated by long chain detection is executed by a |
| 59 | * call_rcu thread, which keeps lock-freedom of add and remove. |
| 60 | * - Resize operations are protected by a mutex. |
| 61 | * - The removal operation is split in two parts: first, a "removed" |
| 62 | * flag is set in the next pointer within the node to remove. Then, |
| 63 | * a "garbage collection" is performed in the bucket containing the |
| 64 | * removed node (from the start of the bucket up to the removed node). |
| 65 | * All encountered nodes with "removed" flag set in their next |
| 66 | * pointers are removed from the linked-list. If the cmpxchg used for |
| 67 | * removal fails (due to concurrent garbage-collection or concurrent |
| 68 | * add), we retry from the beginning of the bucket. This ensures that |
| 69 | * the node with "removed" flag set is removed from the hash table |
| 70 | * (not visible to lookups anymore) before the RCU read-side critical |
| 71 | * section held across removal ends. Furthermore, this ensures that |
| 72 | * the node with "removed" flag set is removed from the linked-list |
| 73 | * before its memory is reclaimed. Only the thread which removal |
| 74 | * successfully set the "removed" flag (with a cmpxchg) into a node's |
| 75 | * next pointer is considered to have succeeded its removal (and thus |
| 76 | * owns the node to reclaim). Because we garbage-collect starting from |
| 77 | * an invariant node (the start-of-bucket bucket node) up to the |
| 78 | * "removed" node (or find a reverse-hash that is higher), we are sure |
| 79 | * that a successful traversal of the chain leads to a chain that is |
| 80 | * present in the linked-list (the start node is never removed) and |
| 81 | * that is does not contain the "removed" node anymore, even if |
| 82 | * concurrent delete/add operations are changing the structure of the |
| 83 | * list concurrently. |
| 84 | * - The add operation performs gargage collection of buckets if it |
| 85 | * encounters nodes with removed flag set in the bucket where it wants |
| 86 | * to add its new node. This ensures lock-freedom of add operation by |
| 87 | * helping the remover unlink nodes from the list rather than to wait |
| 88 | * for it do to so. |
| 89 | * - A RCU "order table" indexed by log2(hash index) is copied and |
| 90 | * expanded by the resize operation. This order table allows finding |
| 91 | * the "bucket node" tables. |
| 92 | * - There is one bucket node table per hash index order. The size of |
| 93 | * each bucket node table is half the number of hashes contained in |
| 94 | * this order (except for order 0). |
| 95 | * - synchronzie_rcu is used to garbage-collect the old bucket node table. |
| 96 | * - The per-order bucket node tables contain a compact version of the |
| 97 | * hash table nodes. These tables are invariant after they are |
| 98 | * populated into the hash table. |
| 99 | * |
| 100 | * Bucket node tables: |
| 101 | * |
| 102 | * hash table hash table the last all bucket node tables |
| 103 | * order size bucket node 0 1 2 3 4 5 6(index) |
| 104 | * table size |
| 105 | * 0 1 1 1 |
| 106 | * 1 2 1 1 1 |
| 107 | * 2 4 2 1 1 2 |
| 108 | * 3 8 4 1 1 2 4 |
| 109 | * 4 16 8 1 1 2 4 8 |
| 110 | * 5 32 16 1 1 2 4 8 16 |
| 111 | * 6 64 32 1 1 2 4 8 16 32 |
| 112 | * |
| 113 | * When growing/shrinking, we only focus on the last bucket node table |
| 114 | * which size is (!order ? 1 : (1 << (order -1))). |
| 115 | * |
| 116 | * Example for growing/shrinking: |
| 117 | * grow hash table from order 5 to 6: init the index=6 bucket node table |
| 118 | * shrink hash table from order 6 to 5: fini the index=6 bucket node table |
| 119 | * |
| 120 | * A bit of ascii art explanation: |
| 121 | * |
| 122 | * Order index is the off-by-one compare to the actual power of 2 because |
| 123 | * we use index 0 to deal with the 0 special-case. |
| 124 | * |
| 125 | * This shows the nodes for a small table ordered by reversed bits: |
| 126 | * |
| 127 | * bits reverse |
| 128 | * 0 000 000 |
| 129 | * 4 100 001 |
| 130 | * 2 010 010 |
| 131 | * 6 110 011 |
| 132 | * 1 001 100 |
| 133 | * 5 101 101 |
| 134 | * 3 011 110 |
| 135 | * 7 111 111 |
| 136 | * |
| 137 | * This shows the nodes in order of non-reversed bits, linked by |
| 138 | * reversed-bit order. |
| 139 | * |
| 140 | * order bits reverse |
| 141 | * 0 0 000 000 |
| 142 | * 1 | 1 001 100 <- |
| 143 | * 2 | | 2 010 010 <- | |
| 144 | * | | | 3 011 110 | <- | |
| 145 | * 3 -> | | | 4 100 001 | | |
| 146 | * -> | | 5 101 101 | |
| 147 | * -> | 6 110 011 |
| 148 | * -> 7 111 111 |
| 149 | */ |
| 150 | |
| 151 | #define _LGPL_SOURCE |
| 152 | #include <stdlib.h> |
| 153 | #include <errno.h> |
| 154 | #include <assert.h> |
| 155 | #include <stdio.h> |
| 156 | #include <stdint.h> |
| 157 | #include <string.h> |
| 158 | |
| 159 | #include "config.h" |
| 160 | #include <urcu.h> |
| 161 | #include <urcu-call-rcu.h> |
| 162 | #include <urcu/arch.h> |
| 163 | #include <urcu/uatomic.h> |
| 164 | #include <urcu/compiler.h> |
| 165 | #include <urcu/rculfhash.h> |
| 166 | #include <stdio.h> |
| 167 | #include <pthread.h> |
| 168 | |
| 169 | #ifdef DEBUG |
| 170 | #define dbg_printf(fmt, args...) printf("[debug rculfhash] " fmt, ## args) |
| 171 | #else |
| 172 | #define dbg_printf(fmt, args...) |
| 173 | #endif |
| 174 | |
| 175 | /* |
| 176 | * Split-counters lazily update the global counter each 1024 |
| 177 | * addition/removal. It automatically keeps track of resize required. |
| 178 | * We use the bucket length as indicator for need to expand for small |
| 179 | * tables and machines lacking per-cpu data suppport. |
| 180 | */ |
| 181 | #define COUNT_COMMIT_ORDER 10 |
| 182 | #define DEFAULT_SPLIT_COUNT_MASK 0xFUL |
| 183 | #define CHAIN_LEN_TARGET 1 |
| 184 | #define CHAIN_LEN_RESIZE_THRESHOLD 3 |
| 185 | |
| 186 | /* |
| 187 | * Define the minimum table size. |
| 188 | */ |
| 189 | #define MIN_TABLE_SIZE 1 |
| 190 | |
| 191 | #if (CAA_BITS_PER_LONG == 32) |
| 192 | #define MAX_TABLE_ORDER 32 |
| 193 | #else |
| 194 | #define MAX_TABLE_ORDER 64 |
| 195 | #endif |
| 196 | |
| 197 | /* |
| 198 | * Minimum number of bucket nodes to touch per thread to parallelize grow/shrink. |
| 199 | */ |
| 200 | #define MIN_PARTITION_PER_THREAD_ORDER 12 |
| 201 | #define MIN_PARTITION_PER_THREAD (1UL << MIN_PARTITION_PER_THREAD_ORDER) |
| 202 | |
| 203 | #ifndef min |
| 204 | #define min(a, b) ((a) < (b) ? (a) : (b)) |
| 205 | #endif |
| 206 | |
| 207 | #ifndef max |
| 208 | #define max(a, b) ((a) > (b) ? (a) : (b)) |
| 209 | #endif |
| 210 | |
| 211 | /* |
| 212 | * The removed flag needs to be updated atomically with the pointer. |
| 213 | * It indicates that no node must attach to the node scheduled for |
| 214 | * removal, and that node garbage collection must be performed. |
| 215 | * The bucket flag does not require to be updated atomically with the |
| 216 | * pointer, but it is added as a pointer low bit flag to save space. |
| 217 | */ |
| 218 | #define REMOVED_FLAG (1UL << 0) |
| 219 | #define BUCKET_FLAG (1UL << 1) |
| 220 | #define FLAGS_MASK ((1UL << 2) - 1) |
| 221 | |
| 222 | /* Value of the end pointer. Should not interact with flags. */ |
| 223 | #define END_VALUE NULL |
| 224 | |
| 225 | /* |
| 226 | * ht_items_count: Split-counters counting the number of node addition |
| 227 | * and removal in the table. Only used if the CDS_LFHT_ACCOUNTING flag |
| 228 | * is set at hash table creation. |
| 229 | * |
| 230 | * These are free-running counters, never reset to zero. They count the |
| 231 | * number of add/remove, and trigger every (1 << COUNT_COMMIT_ORDER) |
| 232 | * operations to update the global counter. We choose a power-of-2 value |
| 233 | * for the trigger to deal with 32 or 64-bit overflow of the counter. |
| 234 | */ |
| 235 | struct ht_items_count { |
| 236 | unsigned long add, del; |
| 237 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
| 238 | |
| 239 | /* |
| 240 | * rcu_level: Contains the per order-index-level bucket node table. The |
| 241 | * size of each bucket node table is half the number of hashes contained |
| 242 | * in this order (except for order 0). The minimum allocation size |
| 243 | * parameter allows combining the bucket node arrays of the lowermost |
| 244 | * levels to improve cache locality for small index orders. |
| 245 | */ |
| 246 | struct rcu_level { |
| 247 | /* Note: manually update allocation length when adding a field */ |
| 248 | struct cds_lfht_node nodes[0]; |
| 249 | }; |
| 250 | |
| 251 | /* |
| 252 | * rcu_table: Contains the size and desired new size if a resize |
| 253 | * operation is in progress, as well as the statically-sized array of |
| 254 | * rcu_level pointers. |
| 255 | */ |
| 256 | struct rcu_table { |
| 257 | unsigned long size; /* always a power of 2, shared (RCU) */ |
| 258 | unsigned long resize_target; |
| 259 | int resize_initiated; |
| 260 | struct rcu_level *tbl[MAX_TABLE_ORDER]; |
| 261 | }; |
| 262 | |
| 263 | /* |
| 264 | * cds_lfht: Top-level data structure representing a lock-free hash |
| 265 | * table. Defined in the implementation file to make it be an opaque |
| 266 | * cookie to users. |
| 267 | */ |
| 268 | struct cds_lfht { |
| 269 | struct rcu_table t; |
| 270 | unsigned long min_alloc_order; |
| 271 | unsigned long min_alloc_size; |
| 272 | int flags; |
| 273 | /* |
| 274 | * We need to put the work threads offline (QSBR) when taking this |
| 275 | * mutex, because we use synchronize_rcu within this mutex critical |
| 276 | * section, which waits on read-side critical sections, and could |
| 277 | * therefore cause grace-period deadlock if we hold off RCU G.P. |
| 278 | * completion. |
| 279 | */ |
| 280 | pthread_mutex_t resize_mutex; /* resize mutex: add/del mutex */ |
| 281 | unsigned int in_progress_resize, in_progress_destroy; |
| 282 | void (*cds_lfht_call_rcu)(struct rcu_head *head, |
| 283 | void (*func)(struct rcu_head *head)); |
| 284 | void (*cds_lfht_synchronize_rcu)(void); |
| 285 | void (*cds_lfht_rcu_read_lock)(void); |
| 286 | void (*cds_lfht_rcu_read_unlock)(void); |
| 287 | void (*cds_lfht_rcu_thread_offline)(void); |
| 288 | void (*cds_lfht_rcu_thread_online)(void); |
| 289 | void (*cds_lfht_rcu_register_thread)(void); |
| 290 | void (*cds_lfht_rcu_unregister_thread)(void); |
| 291 | pthread_attr_t *resize_attr; /* Resize threads attributes */ |
| 292 | long count; /* global approximate item count */ |
| 293 | struct ht_items_count *split_count; /* split item count */ |
| 294 | }; |
| 295 | |
| 296 | /* |
| 297 | * rcu_resize_work: Contains arguments passed to RCU worker thread |
| 298 | * responsible for performing lazy resize. |
| 299 | */ |
| 300 | struct rcu_resize_work { |
| 301 | struct rcu_head head; |
| 302 | struct cds_lfht *ht; |
| 303 | }; |
| 304 | |
| 305 | /* |
| 306 | * partition_resize_work: Contains arguments passed to worker threads |
| 307 | * executing the hash table resize on partitions of the hash table |
| 308 | * assigned to each processor's worker thread. |
| 309 | */ |
| 310 | struct partition_resize_work { |
| 311 | pthread_t thread_id; |
| 312 | struct cds_lfht *ht; |
| 313 | unsigned long i, start, len; |
| 314 | void (*fct)(struct cds_lfht *ht, unsigned long i, |
| 315 | unsigned long start, unsigned long len); |
| 316 | }; |
| 317 | |
| 318 | static |
| 319 | void _cds_lfht_add(struct cds_lfht *ht, |
| 320 | cds_lfht_match_fct match, |
| 321 | const void *key, |
| 322 | unsigned long size, |
| 323 | struct cds_lfht_node *node, |
| 324 | struct cds_lfht_iter *unique_ret, |
| 325 | int bucket); |
| 326 | |
| 327 | /* |
| 328 | * Algorithm to reverse bits in a word by lookup table, extended to |
| 329 | * 64-bit words. |
| 330 | * Source: |
| 331 | * http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable |
| 332 | * Originally from Public Domain. |
| 333 | */ |
| 334 | |
| 335 | static const uint8_t BitReverseTable256[256] = |
| 336 | { |
| 337 | #define R2(n) (n), (n) + 2*64, (n) + 1*64, (n) + 3*64 |
| 338 | #define R4(n) R2(n), R2((n) + 2*16), R2((n) + 1*16), R2((n) + 3*16) |
| 339 | #define R6(n) R4(n), R4((n) + 2*4 ), R4((n) + 1*4 ), R4((n) + 3*4 ) |
| 340 | R6(0), R6(2), R6(1), R6(3) |
| 341 | }; |
| 342 | #undef R2 |
| 343 | #undef R4 |
| 344 | #undef R6 |
| 345 | |
| 346 | static |
| 347 | uint8_t bit_reverse_u8(uint8_t v) |
| 348 | { |
| 349 | return BitReverseTable256[v]; |
| 350 | } |
| 351 | |
| 352 | static __attribute__((unused)) |
| 353 | uint32_t bit_reverse_u32(uint32_t v) |
| 354 | { |
| 355 | return ((uint32_t) bit_reverse_u8(v) << 24) | |
| 356 | ((uint32_t) bit_reverse_u8(v >> 8) << 16) | |
| 357 | ((uint32_t) bit_reverse_u8(v >> 16) << 8) | |
| 358 | ((uint32_t) bit_reverse_u8(v >> 24)); |
| 359 | } |
| 360 | |
| 361 | static __attribute__((unused)) |
| 362 | uint64_t bit_reverse_u64(uint64_t v) |
| 363 | { |
| 364 | return ((uint64_t) bit_reverse_u8(v) << 56) | |
| 365 | ((uint64_t) bit_reverse_u8(v >> 8) << 48) | |
| 366 | ((uint64_t) bit_reverse_u8(v >> 16) << 40) | |
| 367 | ((uint64_t) bit_reverse_u8(v >> 24) << 32) | |
| 368 | ((uint64_t) bit_reverse_u8(v >> 32) << 24) | |
| 369 | ((uint64_t) bit_reverse_u8(v >> 40) << 16) | |
| 370 | ((uint64_t) bit_reverse_u8(v >> 48) << 8) | |
| 371 | ((uint64_t) bit_reverse_u8(v >> 56)); |
| 372 | } |
| 373 | |
| 374 | static |
| 375 | unsigned long bit_reverse_ulong(unsigned long v) |
| 376 | { |
| 377 | #if (CAA_BITS_PER_LONG == 32) |
| 378 | return bit_reverse_u32(v); |
| 379 | #else |
| 380 | return bit_reverse_u64(v); |
| 381 | #endif |
| 382 | } |
| 383 | |
| 384 | /* |
| 385 | * fls: returns the position of the most significant bit. |
| 386 | * Returns 0 if no bit is set, else returns the position of the most |
| 387 | * significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit). |
| 388 | */ |
| 389 | #if defined(__i386) || defined(__x86_64) |
| 390 | static inline |
| 391 | unsigned int fls_u32(uint32_t x) |
| 392 | { |
| 393 | int r; |
| 394 | |
| 395 | asm("bsrl %1,%0\n\t" |
| 396 | "jnz 1f\n\t" |
| 397 | "movl $-1,%0\n\t" |
| 398 | "1:\n\t" |
| 399 | : "=r" (r) : "rm" (x)); |
| 400 | return r + 1; |
| 401 | } |
| 402 | #define HAS_FLS_U32 |
| 403 | #endif |
| 404 | |
| 405 | #if defined(__x86_64) |
| 406 | static inline |
| 407 | unsigned int fls_u64(uint64_t x) |
| 408 | { |
| 409 | long r; |
| 410 | |
| 411 | asm("bsrq %1,%0\n\t" |
| 412 | "jnz 1f\n\t" |
| 413 | "movq $-1,%0\n\t" |
| 414 | "1:\n\t" |
| 415 | : "=r" (r) : "rm" (x)); |
| 416 | return r + 1; |
| 417 | } |
| 418 | #define HAS_FLS_U64 |
| 419 | #endif |
| 420 | |
| 421 | #ifndef HAS_FLS_U64 |
| 422 | static __attribute__((unused)) |
| 423 | unsigned int fls_u64(uint64_t x) |
| 424 | { |
| 425 | unsigned int r = 64; |
| 426 | |
| 427 | if (!x) |
| 428 | return 0; |
| 429 | |
| 430 | if (!(x & 0xFFFFFFFF00000000ULL)) { |
| 431 | x <<= 32; |
| 432 | r -= 32; |
| 433 | } |
| 434 | if (!(x & 0xFFFF000000000000ULL)) { |
| 435 | x <<= 16; |
| 436 | r -= 16; |
| 437 | } |
| 438 | if (!(x & 0xFF00000000000000ULL)) { |
| 439 | x <<= 8; |
| 440 | r -= 8; |
| 441 | } |
| 442 | if (!(x & 0xF000000000000000ULL)) { |
| 443 | x <<= 4; |
| 444 | r -= 4; |
| 445 | } |
| 446 | if (!(x & 0xC000000000000000ULL)) { |
| 447 | x <<= 2; |
| 448 | r -= 2; |
| 449 | } |
| 450 | if (!(x & 0x8000000000000000ULL)) { |
| 451 | x <<= 1; |
| 452 | r -= 1; |
| 453 | } |
| 454 | return r; |
| 455 | } |
| 456 | #endif |
| 457 | |
| 458 | #ifndef HAS_FLS_U32 |
| 459 | static __attribute__((unused)) |
| 460 | unsigned int fls_u32(uint32_t x) |
| 461 | { |
| 462 | unsigned int r = 32; |
| 463 | |
| 464 | if (!x) |
| 465 | return 0; |
| 466 | if (!(x & 0xFFFF0000U)) { |
| 467 | x <<= 16; |
| 468 | r -= 16; |
| 469 | } |
| 470 | if (!(x & 0xFF000000U)) { |
| 471 | x <<= 8; |
| 472 | r -= 8; |
| 473 | } |
| 474 | if (!(x & 0xF0000000U)) { |
| 475 | x <<= 4; |
| 476 | r -= 4; |
| 477 | } |
| 478 | if (!(x & 0xC0000000U)) { |
| 479 | x <<= 2; |
| 480 | r -= 2; |
| 481 | } |
| 482 | if (!(x & 0x80000000U)) { |
| 483 | x <<= 1; |
| 484 | r -= 1; |
| 485 | } |
| 486 | return r; |
| 487 | } |
| 488 | #endif |
| 489 | |
| 490 | unsigned int fls_ulong(unsigned long x) |
| 491 | { |
| 492 | #if (CAA_BITS_PER_LONG == 32) |
| 493 | return fls_u32(x); |
| 494 | #else |
| 495 | return fls_u64(x); |
| 496 | #endif |
| 497 | } |
| 498 | |
| 499 | /* |
| 500 | * Return the minimum order for which x <= (1UL << order). |
| 501 | * Return -1 if x is 0. |
| 502 | */ |
| 503 | int get_count_order_u32(uint32_t x) |
| 504 | { |
| 505 | if (!x) |
| 506 | return -1; |
| 507 | |
| 508 | return fls_u32(x - 1); |
| 509 | } |
| 510 | |
| 511 | /* |
| 512 | * Return the minimum order for which x <= (1UL << order). |
| 513 | * Return -1 if x is 0. |
| 514 | */ |
| 515 | int get_count_order_ulong(unsigned long x) |
| 516 | { |
| 517 | if (!x) |
| 518 | return -1; |
| 519 | |
| 520 | return fls_ulong(x - 1); |
| 521 | } |
| 522 | |
| 523 | #ifdef POISON_FREE |
| 524 | #define poison_free(ptr) \ |
| 525 | do { \ |
| 526 | if (ptr) { \ |
| 527 | memset(ptr, 0x42, sizeof(*(ptr))); \ |
| 528 | free(ptr); \ |
| 529 | } \ |
| 530 | } while (0) |
| 531 | #else |
| 532 | #define poison_free(ptr) free(ptr) |
| 533 | #endif |
| 534 | |
| 535 | static |
| 536 | void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth); |
| 537 | |
| 538 | static |
| 539 | void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size, |
| 540 | unsigned long count); |
| 541 | |
| 542 | static long nr_cpus_mask = -1; |
| 543 | static long split_count_mask = -1; |
| 544 | |
| 545 | #if defined(HAVE_SYSCONF) |
| 546 | static void ht_init_nr_cpus_mask(void) |
| 547 | { |
| 548 | long maxcpus; |
| 549 | |
| 550 | maxcpus = sysconf(_SC_NPROCESSORS_CONF); |
| 551 | if (maxcpus <= 0) { |
| 552 | nr_cpus_mask = -2; |
| 553 | return; |
| 554 | } |
| 555 | /* |
| 556 | * round up number of CPUs to next power of two, so we |
| 557 | * can use & for modulo. |
| 558 | */ |
| 559 | maxcpus = 1UL << get_count_order_ulong(maxcpus); |
| 560 | nr_cpus_mask = maxcpus - 1; |
| 561 | } |
| 562 | #else /* #if defined(HAVE_SYSCONF) */ |
| 563 | static void ht_init_nr_cpus_mask(void) |
| 564 | { |
| 565 | nr_cpus_mask = -2; |
| 566 | } |
| 567 | #endif /* #else #if defined(HAVE_SYSCONF) */ |
| 568 | |
| 569 | static |
| 570 | void alloc_split_items_count(struct cds_lfht *ht) |
| 571 | { |
| 572 | struct ht_items_count *count; |
| 573 | |
| 574 | if (nr_cpus_mask == -1) { |
| 575 | ht_init_nr_cpus_mask(); |
| 576 | if (nr_cpus_mask < 0) |
| 577 | split_count_mask = DEFAULT_SPLIT_COUNT_MASK; |
| 578 | else |
| 579 | split_count_mask = nr_cpus_mask; |
| 580 | } |
| 581 | |
| 582 | assert(split_count_mask >= 0); |
| 583 | |
| 584 | if (ht->flags & CDS_LFHT_ACCOUNTING) { |
| 585 | ht->split_count = calloc(split_count_mask + 1, sizeof(*count)); |
| 586 | assert(ht->split_count); |
| 587 | } else { |
| 588 | ht->split_count = NULL; |
| 589 | } |
| 590 | } |
| 591 | |
| 592 | static |
| 593 | void free_split_items_count(struct cds_lfht *ht) |
| 594 | { |
| 595 | poison_free(ht->split_count); |
| 596 | } |
| 597 | |
| 598 | #if defined(HAVE_SCHED_GETCPU) |
| 599 | static |
| 600 | int ht_get_split_count_index(unsigned long hash) |
| 601 | { |
| 602 | int cpu; |
| 603 | |
| 604 | assert(split_count_mask >= 0); |
| 605 | cpu = sched_getcpu(); |
| 606 | if (caa_unlikely(cpu < 0)) |
| 607 | return hash & split_count_mask; |
| 608 | else |
| 609 | return cpu & split_count_mask; |
| 610 | } |
| 611 | #else /* #if defined(HAVE_SCHED_GETCPU) */ |
| 612 | static |
| 613 | int ht_get_split_count_index(unsigned long hash) |
| 614 | { |
| 615 | return hash & split_count_mask; |
| 616 | } |
| 617 | #endif /* #else #if defined(HAVE_SCHED_GETCPU) */ |
| 618 | |
| 619 | static |
| 620 | void ht_count_add(struct cds_lfht *ht, unsigned long size, unsigned long hash) |
| 621 | { |
| 622 | unsigned long split_count; |
| 623 | int index; |
| 624 | |
| 625 | if (caa_unlikely(!ht->split_count)) |
| 626 | return; |
| 627 | index = ht_get_split_count_index(hash); |
| 628 | split_count = uatomic_add_return(&ht->split_count[index].add, 1); |
| 629 | if (caa_unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) { |
| 630 | long count; |
| 631 | |
| 632 | dbg_printf("add split count %lu\n", split_count); |
| 633 | count = uatomic_add_return(&ht->count, |
| 634 | 1UL << COUNT_COMMIT_ORDER); |
| 635 | /* If power of 2 */ |
| 636 | if (!(count & (count - 1))) { |
| 637 | if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) < size) |
| 638 | return; |
| 639 | dbg_printf("add set global %ld\n", count); |
| 640 | cds_lfht_resize_lazy_count(ht, size, |
| 641 | count >> (CHAIN_LEN_TARGET - 1)); |
| 642 | } |
| 643 | } |
| 644 | } |
| 645 | |
| 646 | static |
| 647 | void ht_count_del(struct cds_lfht *ht, unsigned long size, unsigned long hash) |
| 648 | { |
| 649 | unsigned long split_count; |
| 650 | int index; |
| 651 | |
| 652 | if (caa_unlikely(!ht->split_count)) |
| 653 | return; |
| 654 | index = ht_get_split_count_index(hash); |
| 655 | split_count = uatomic_add_return(&ht->split_count[index].del, 1); |
| 656 | if (caa_unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) { |
| 657 | long count; |
| 658 | |
| 659 | dbg_printf("del split count %lu\n", split_count); |
| 660 | count = uatomic_add_return(&ht->count, |
| 661 | -(1UL << COUNT_COMMIT_ORDER)); |
| 662 | /* If power of 2 */ |
| 663 | if (!(count & (count - 1))) { |
| 664 | if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) >= size) |
| 665 | return; |
| 666 | dbg_printf("del set global %ld\n", count); |
| 667 | /* |
| 668 | * Don't shrink table if the number of nodes is below a |
| 669 | * certain threshold. |
| 670 | */ |
| 671 | if (count < (1UL << COUNT_COMMIT_ORDER) * (split_count_mask + 1)) |
| 672 | return; |
| 673 | cds_lfht_resize_lazy_count(ht, size, |
| 674 | count >> (CHAIN_LEN_TARGET - 1)); |
| 675 | } |
| 676 | } |
| 677 | } |
| 678 | |
| 679 | static |
| 680 | void check_resize(struct cds_lfht *ht, unsigned long size, uint32_t chain_len) |
| 681 | { |
| 682 | unsigned long count; |
| 683 | |
| 684 | if (!(ht->flags & CDS_LFHT_AUTO_RESIZE)) |
| 685 | return; |
| 686 | count = uatomic_read(&ht->count); |
| 687 | /* |
| 688 | * Use bucket-local length for small table expand and for |
| 689 | * environments lacking per-cpu data support. |
| 690 | */ |
| 691 | if (count >= (1UL << COUNT_COMMIT_ORDER)) |
| 692 | return; |
| 693 | if (chain_len > 100) |
| 694 | dbg_printf("WARNING: large chain length: %u.\n", |
| 695 | chain_len); |
| 696 | if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD) |
| 697 | cds_lfht_resize_lazy_grow(ht, size, |
| 698 | get_count_order_u32(chain_len - (CHAIN_LEN_TARGET - 1))); |
| 699 | } |
| 700 | |
| 701 | static |
| 702 | struct cds_lfht_node *clear_flag(struct cds_lfht_node *node) |
| 703 | { |
| 704 | return (struct cds_lfht_node *) (((unsigned long) node) & ~FLAGS_MASK); |
| 705 | } |
| 706 | |
| 707 | static |
| 708 | int is_removed(struct cds_lfht_node *node) |
| 709 | { |
| 710 | return ((unsigned long) node) & REMOVED_FLAG; |
| 711 | } |
| 712 | |
| 713 | static |
| 714 | struct cds_lfht_node *flag_removed(struct cds_lfht_node *node) |
| 715 | { |
| 716 | return (struct cds_lfht_node *) (((unsigned long) node) | REMOVED_FLAG); |
| 717 | } |
| 718 | |
| 719 | static |
| 720 | int is_bucket(struct cds_lfht_node *node) |
| 721 | { |
| 722 | return ((unsigned long) node) & BUCKET_FLAG; |
| 723 | } |
| 724 | |
| 725 | static |
| 726 | struct cds_lfht_node *flag_bucket(struct cds_lfht_node *node) |
| 727 | { |
| 728 | return (struct cds_lfht_node *) (((unsigned long) node) | BUCKET_FLAG); |
| 729 | } |
| 730 | |
| 731 | static |
| 732 | struct cds_lfht_node *get_end(void) |
| 733 | { |
| 734 | return (struct cds_lfht_node *) END_VALUE; |
| 735 | } |
| 736 | |
| 737 | static |
| 738 | int is_end(struct cds_lfht_node *node) |
| 739 | { |
| 740 | return clear_flag(node) == (struct cds_lfht_node *) END_VALUE; |
| 741 | } |
| 742 | |
| 743 | static |
| 744 | unsigned long _uatomic_xchg_monotonic_increase(unsigned long *ptr, |
| 745 | unsigned long v) |
| 746 | { |
| 747 | unsigned long old1, old2; |
| 748 | |
| 749 | old1 = uatomic_read(ptr); |
| 750 | do { |
| 751 | old2 = old1; |
| 752 | if (old2 >= v) |
| 753 | return old2; |
| 754 | } while ((old1 = uatomic_cmpxchg(ptr, old2, v)) != old2); |
| 755 | return old2; |
| 756 | } |
| 757 | |
| 758 | static |
| 759 | struct cds_lfht_node *lookup_bucket(struct cds_lfht *ht, unsigned long size, |
| 760 | unsigned long hash) |
| 761 | { |
| 762 | unsigned long index, order; |
| 763 | |
| 764 | assert(size > 0); |
| 765 | index = hash & (size - 1); |
| 766 | |
| 767 | if (index < ht->min_alloc_size) { |
| 768 | dbg_printf("lookup hash %lu index %lu order 0 aridx 0\n", |
| 769 | hash, index); |
| 770 | return &ht->t.tbl[0]->nodes[index]; |
| 771 | } |
| 772 | /* |
| 773 | * equivalent to get_count_order_ulong(index + 1), but optimizes |
| 774 | * away the non-existing 0 special-case for |
| 775 | * get_count_order_ulong. |
| 776 | */ |
| 777 | order = fls_ulong(index); |
| 778 | dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n", |
| 779 | hash, index, order, index & ((1UL << (order - 1)) - 1)); |
| 780 | return &ht->t.tbl[order]->nodes[index & ((1UL << (order - 1)) - 1)]; |
| 781 | } |
| 782 | |
| 783 | /* |
| 784 | * Remove all logically deleted nodes from a bucket up to a certain node key. |
| 785 | */ |
| 786 | static |
| 787 | void _cds_lfht_gc_bucket(struct cds_lfht_node *bucket, struct cds_lfht_node *node) |
| 788 | { |
| 789 | struct cds_lfht_node *iter_prev, *iter, *next, *new_next; |
| 790 | |
| 791 | assert(!is_bucket(bucket)); |
| 792 | assert(!is_removed(bucket)); |
| 793 | assert(!is_bucket(node)); |
| 794 | assert(!is_removed(node)); |
| 795 | for (;;) { |
| 796 | iter_prev = bucket; |
| 797 | /* We can always skip the bucket node initially */ |
| 798 | iter = rcu_dereference(iter_prev->next); |
| 799 | assert(!is_removed(iter)); |
| 800 | assert(iter_prev->reverse_hash <= node->reverse_hash); |
| 801 | /* |
| 802 | * We should never be called with bucket (start of chain) |
| 803 | * and logically removed node (end of path compression |
| 804 | * marker) being the actual same node. This would be a |
| 805 | * bug in the algorithm implementation. |
| 806 | */ |
| 807 | assert(bucket != node); |
| 808 | for (;;) { |
| 809 | if (caa_unlikely(is_end(iter))) |
| 810 | return; |
| 811 | if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash)) |
| 812 | return; |
| 813 | next = rcu_dereference(clear_flag(iter)->next); |
| 814 | if (caa_likely(is_removed(next))) |
| 815 | break; |
| 816 | iter_prev = clear_flag(iter); |
| 817 | iter = next; |
| 818 | } |
| 819 | assert(!is_removed(iter)); |
| 820 | if (is_bucket(iter)) |
| 821 | new_next = flag_bucket(clear_flag(next)); |
| 822 | else |
| 823 | new_next = clear_flag(next); |
| 824 | (void) uatomic_cmpxchg(&iter_prev->next, iter, new_next); |
| 825 | } |
| 826 | return; |
| 827 | } |
| 828 | |
| 829 | static |
| 830 | int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size, |
| 831 | struct cds_lfht_node *old_node, |
| 832 | struct cds_lfht_node *old_next, |
| 833 | struct cds_lfht_node *new_node) |
| 834 | { |
| 835 | struct cds_lfht_node *bucket, *ret_next; |
| 836 | |
| 837 | if (!old_node) /* Return -ENOENT if asked to replace NULL node */ |
| 838 | return -ENOENT; |
| 839 | |
| 840 | assert(!is_removed(old_node)); |
| 841 | assert(!is_bucket(old_node)); |
| 842 | assert(!is_removed(new_node)); |
| 843 | assert(!is_bucket(new_node)); |
| 844 | assert(new_node != old_node); |
| 845 | for (;;) { |
| 846 | /* Insert after node to be replaced */ |
| 847 | if (is_removed(old_next)) { |
| 848 | /* |
| 849 | * Too late, the old node has been removed under us |
| 850 | * between lookup and replace. Fail. |
| 851 | */ |
| 852 | return -ENOENT; |
| 853 | } |
| 854 | assert(!is_bucket(old_next)); |
| 855 | assert(new_node != clear_flag(old_next)); |
| 856 | new_node->next = clear_flag(old_next); |
| 857 | /* |
| 858 | * Here is the whole trick for lock-free replace: we add |
| 859 | * the replacement node _after_ the node we want to |
| 860 | * replace by atomically setting its next pointer at the |
| 861 | * same time we set its removal flag. Given that |
| 862 | * the lookups/get next use an iterator aware of the |
| 863 | * next pointer, they will either skip the old node due |
| 864 | * to the removal flag and see the new node, or use |
| 865 | * the old node, but will not see the new one. |
| 866 | */ |
| 867 | ret_next = uatomic_cmpxchg(&old_node->next, |
| 868 | old_next, flag_removed(new_node)); |
| 869 | if (ret_next == old_next) |
| 870 | break; /* We performed the replacement. */ |
| 871 | old_next = ret_next; |
| 872 | } |
| 873 | |
| 874 | /* |
| 875 | * Ensure that the old node is not visible to readers anymore: |
| 876 | * lookup for the node, and remove it (along with any other |
| 877 | * logically removed node) if found. |
| 878 | */ |
| 879 | bucket = lookup_bucket(ht, size, bit_reverse_ulong(old_node->reverse_hash)); |
| 880 | _cds_lfht_gc_bucket(bucket, new_node); |
| 881 | |
| 882 | assert(is_removed(rcu_dereference(old_node->next))); |
| 883 | return 0; |
| 884 | } |
| 885 | |
| 886 | /* |
| 887 | * A non-NULL unique_ret pointer uses the "add unique" (or uniquify) add |
| 888 | * mode. A NULL unique_ret allows creation of duplicate keys. |
| 889 | */ |
| 890 | static |
| 891 | void _cds_lfht_add(struct cds_lfht *ht, |
| 892 | cds_lfht_match_fct match, |
| 893 | const void *key, |
| 894 | unsigned long size, |
| 895 | struct cds_lfht_node *node, |
| 896 | struct cds_lfht_iter *unique_ret, |
| 897 | int bucket_flag) |
| 898 | { |
| 899 | struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next, |
| 900 | *return_node; |
| 901 | struct cds_lfht_node *bucket; |
| 902 | |
| 903 | assert(!is_bucket(node)); |
| 904 | assert(!is_removed(node)); |
| 905 | bucket = lookup_bucket(ht, size, bit_reverse_ulong(node->reverse_hash)); |
| 906 | for (;;) { |
| 907 | uint32_t chain_len = 0; |
| 908 | |
| 909 | /* |
| 910 | * iter_prev points to the non-removed node prior to the |
| 911 | * insert location. |
| 912 | */ |
| 913 | iter_prev = bucket; |
| 914 | /* We can always skip the bucket node initially */ |
| 915 | iter = rcu_dereference(iter_prev->next); |
| 916 | assert(iter_prev->reverse_hash <= node->reverse_hash); |
| 917 | for (;;) { |
| 918 | if (caa_unlikely(is_end(iter))) |
| 919 | goto insert; |
| 920 | if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash)) |
| 921 | goto insert; |
| 922 | |
| 923 | /* bucket node is the first node of the identical-hash-value chain */ |
| 924 | if (bucket_flag && clear_flag(iter)->reverse_hash == node->reverse_hash) |
| 925 | goto insert; |
| 926 | |
| 927 | next = rcu_dereference(clear_flag(iter)->next); |
| 928 | if (caa_unlikely(is_removed(next))) |
| 929 | goto gc_node; |
| 930 | |
| 931 | /* uniquely add */ |
| 932 | if (unique_ret |
| 933 | && !is_bucket(next) |
| 934 | && clear_flag(iter)->reverse_hash == node->reverse_hash) { |
| 935 | struct cds_lfht_iter d_iter = { .node = node, .next = iter, }; |
| 936 | |
| 937 | /* |
| 938 | * uniquely adding inserts the node as the first |
| 939 | * node of the identical-hash-value node chain. |
| 940 | * |
| 941 | * This semantic ensures no duplicated keys |
| 942 | * should ever be observable in the table |
| 943 | * (including observe one node by one node |
| 944 | * by forward iterations) |
| 945 | */ |
| 946 | cds_lfht_next_duplicate(ht, match, key, &d_iter); |
| 947 | if (!d_iter.node) |
| 948 | goto insert; |
| 949 | |
| 950 | *unique_ret = d_iter; |
| 951 | return; |
| 952 | } |
| 953 | |
| 954 | /* Only account for identical reverse hash once */ |
| 955 | if (iter_prev->reverse_hash != clear_flag(iter)->reverse_hash |
| 956 | && !is_bucket(next)) |
| 957 | check_resize(ht, size, ++chain_len); |
| 958 | iter_prev = clear_flag(iter); |
| 959 | iter = next; |
| 960 | } |
| 961 | |
| 962 | insert: |
| 963 | assert(node != clear_flag(iter)); |
| 964 | assert(!is_removed(iter_prev)); |
| 965 | assert(!is_removed(iter)); |
| 966 | assert(iter_prev != node); |
| 967 | if (!bucket_flag) |
| 968 | node->next = clear_flag(iter); |
| 969 | else |
| 970 | node->next = flag_bucket(clear_flag(iter)); |
| 971 | if (is_bucket(iter)) |
| 972 | new_node = flag_bucket(node); |
| 973 | else |
| 974 | new_node = node; |
| 975 | if (uatomic_cmpxchg(&iter_prev->next, iter, |
| 976 | new_node) != iter) { |
| 977 | continue; /* retry */ |
| 978 | } else { |
| 979 | return_node = node; |
| 980 | goto end; |
| 981 | } |
| 982 | |
| 983 | gc_node: |
| 984 | assert(!is_removed(iter)); |
| 985 | if (is_bucket(iter)) |
| 986 | new_next = flag_bucket(clear_flag(next)); |
| 987 | else |
| 988 | new_next = clear_flag(next); |
| 989 | (void) uatomic_cmpxchg(&iter_prev->next, iter, new_next); |
| 990 | /* retry */ |
| 991 | } |
| 992 | end: |
| 993 | if (unique_ret) { |
| 994 | unique_ret->node = return_node; |
| 995 | /* unique_ret->next left unset, never used. */ |
| 996 | } |
| 997 | } |
| 998 | |
| 999 | static |
| 1000 | int _cds_lfht_del(struct cds_lfht *ht, unsigned long size, |
| 1001 | struct cds_lfht_node *node, |
| 1002 | int bucket_removal) |
| 1003 | { |
| 1004 | struct cds_lfht_node *bucket, *next, *old; |
| 1005 | |
| 1006 | if (!node) /* Return -ENOENT if asked to delete NULL node */ |
| 1007 | return -ENOENT; |
| 1008 | |
| 1009 | /* logically delete the node */ |
| 1010 | assert(!is_bucket(node)); |
| 1011 | assert(!is_removed(node)); |
| 1012 | old = rcu_dereference(node->next); |
| 1013 | do { |
| 1014 | struct cds_lfht_node *new_next; |
| 1015 | |
| 1016 | next = old; |
| 1017 | if (caa_unlikely(is_removed(next))) |
| 1018 | return -ENOENT; |
| 1019 | if (bucket_removal) |
| 1020 | assert(is_bucket(next)); |
| 1021 | else |
| 1022 | assert(!is_bucket(next)); |
| 1023 | new_next = flag_removed(next); |
| 1024 | old = uatomic_cmpxchg(&node->next, next, new_next); |
| 1025 | } while (old != next); |
| 1026 | /* We performed the (logical) deletion. */ |
| 1027 | |
| 1028 | /* |
| 1029 | * Ensure that the node is not visible to readers anymore: lookup for |
| 1030 | * the node, and remove it (along with any other logically removed node) |
| 1031 | * if found. |
| 1032 | */ |
| 1033 | bucket = lookup_bucket(ht, size, bit_reverse_ulong(node->reverse_hash)); |
| 1034 | _cds_lfht_gc_bucket(bucket, node); |
| 1035 | |
| 1036 | assert(is_removed(rcu_dereference(node->next))); |
| 1037 | return 0; |
| 1038 | } |
| 1039 | |
| 1040 | static |
| 1041 | void *partition_resize_thread(void *arg) |
| 1042 | { |
| 1043 | struct partition_resize_work *work = arg; |
| 1044 | |
| 1045 | work->ht->cds_lfht_rcu_register_thread(); |
| 1046 | work->fct(work->ht, work->i, work->start, work->len); |
| 1047 | work->ht->cds_lfht_rcu_unregister_thread(); |
| 1048 | return NULL; |
| 1049 | } |
| 1050 | |
| 1051 | static |
| 1052 | void partition_resize_helper(struct cds_lfht *ht, unsigned long i, |
| 1053 | unsigned long len, |
| 1054 | void (*fct)(struct cds_lfht *ht, unsigned long i, |
| 1055 | unsigned long start, unsigned long len)) |
| 1056 | { |
| 1057 | unsigned long partition_len; |
| 1058 | struct partition_resize_work *work; |
| 1059 | int thread, ret; |
| 1060 | unsigned long nr_threads; |
| 1061 | |
| 1062 | /* |
| 1063 | * Note: nr_cpus_mask + 1 is always power of 2. |
| 1064 | * We spawn just the number of threads we need to satisfy the minimum |
| 1065 | * partition size, up to the number of CPUs in the system. |
| 1066 | */ |
| 1067 | if (nr_cpus_mask > 0) { |
| 1068 | nr_threads = min(nr_cpus_mask + 1, |
| 1069 | len >> MIN_PARTITION_PER_THREAD_ORDER); |
| 1070 | } else { |
| 1071 | nr_threads = 1; |
| 1072 | } |
| 1073 | partition_len = len >> get_count_order_ulong(nr_threads); |
| 1074 | work = calloc(nr_threads, sizeof(*work)); |
| 1075 | assert(work); |
| 1076 | for (thread = 0; thread < nr_threads; thread++) { |
| 1077 | work[thread].ht = ht; |
| 1078 | work[thread].i = i; |
| 1079 | work[thread].len = partition_len; |
| 1080 | work[thread].start = thread * partition_len; |
| 1081 | work[thread].fct = fct; |
| 1082 | ret = pthread_create(&(work[thread].thread_id), ht->resize_attr, |
| 1083 | partition_resize_thread, &work[thread]); |
| 1084 | assert(!ret); |
| 1085 | } |
| 1086 | for (thread = 0; thread < nr_threads; thread++) { |
| 1087 | ret = pthread_join(work[thread].thread_id, NULL); |
| 1088 | assert(!ret); |
| 1089 | } |
| 1090 | free(work); |
| 1091 | } |
| 1092 | |
| 1093 | /* |
| 1094 | * Holding RCU read lock to protect _cds_lfht_add against memory |
| 1095 | * reclaim that could be performed by other call_rcu worker threads (ABA |
| 1096 | * problem). |
| 1097 | * |
| 1098 | * When we reach a certain length, we can split this population phase over |
| 1099 | * many worker threads, based on the number of CPUs available in the system. |
| 1100 | * This should therefore take care of not having the expand lagging behind too |
| 1101 | * many concurrent insertion threads by using the scheduler's ability to |
| 1102 | * schedule bucket node population fairly with insertions. |
| 1103 | */ |
| 1104 | static |
| 1105 | void init_table_populate_partition(struct cds_lfht *ht, unsigned long i, |
| 1106 | unsigned long start, unsigned long len) |
| 1107 | { |
| 1108 | unsigned long j; |
| 1109 | |
| 1110 | assert(i > ht->min_alloc_order); |
| 1111 | ht->cds_lfht_rcu_read_lock(); |
| 1112 | for (j = start; j < start + len; j++) { |
| 1113 | struct cds_lfht_node *new_node = &ht->t.tbl[i]->nodes[j]; |
| 1114 | |
| 1115 | dbg_printf("init populate: i %lu j %lu hash %lu\n", |
| 1116 | i, j, (1UL << (i - 1)) + j); |
| 1117 | new_node->reverse_hash = |
| 1118 | bit_reverse_ulong((1UL << (i - 1)) + j); |
| 1119 | _cds_lfht_add(ht, NULL, NULL, 1UL << (i - 1), |
| 1120 | new_node, NULL, 1); |
| 1121 | } |
| 1122 | ht->cds_lfht_rcu_read_unlock(); |
| 1123 | } |
| 1124 | |
| 1125 | static |
| 1126 | void init_table_populate(struct cds_lfht *ht, unsigned long i, |
| 1127 | unsigned long len) |
| 1128 | { |
| 1129 | assert(nr_cpus_mask != -1); |
| 1130 | if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) { |
| 1131 | ht->cds_lfht_rcu_thread_online(); |
| 1132 | init_table_populate_partition(ht, i, 0, len); |
| 1133 | ht->cds_lfht_rcu_thread_offline(); |
| 1134 | return; |
| 1135 | } |
| 1136 | partition_resize_helper(ht, i, len, init_table_populate_partition); |
| 1137 | } |
| 1138 | |
| 1139 | static |
| 1140 | void init_table(struct cds_lfht *ht, |
| 1141 | unsigned long first_order, unsigned long last_order) |
| 1142 | { |
| 1143 | unsigned long i; |
| 1144 | |
| 1145 | dbg_printf("init table: first_order %lu last_order %lu\n", |
| 1146 | first_order, last_order); |
| 1147 | assert(first_order > ht->min_alloc_order); |
| 1148 | for (i = first_order; i <= last_order; i++) { |
| 1149 | unsigned long len; |
| 1150 | |
| 1151 | len = 1UL << (i - 1); |
| 1152 | dbg_printf("init order %lu len: %lu\n", i, len); |
| 1153 | |
| 1154 | /* Stop expand if the resize target changes under us */ |
| 1155 | if (CMM_LOAD_SHARED(ht->t.resize_target) < (1UL << i)) |
| 1156 | break; |
| 1157 | |
| 1158 | ht->t.tbl[i] = calloc(1, len * sizeof(struct cds_lfht_node)); |
| 1159 | assert(ht->t.tbl[i]); |
| 1160 | |
| 1161 | /* |
| 1162 | * Set all bucket nodes reverse hash values for a level and |
| 1163 | * link all bucket nodes into the table. |
| 1164 | */ |
| 1165 | init_table_populate(ht, i, len); |
| 1166 | |
| 1167 | /* |
| 1168 | * Update table size. |
| 1169 | */ |
| 1170 | cmm_smp_wmb(); /* populate data before RCU size */ |
| 1171 | CMM_STORE_SHARED(ht->t.size, 1UL << i); |
| 1172 | |
| 1173 | dbg_printf("init new size: %lu\n", 1UL << i); |
| 1174 | if (CMM_LOAD_SHARED(ht->in_progress_destroy)) |
| 1175 | break; |
| 1176 | } |
| 1177 | } |
| 1178 | |
| 1179 | /* |
| 1180 | * Holding RCU read lock to protect _cds_lfht_remove against memory |
| 1181 | * reclaim that could be performed by other call_rcu worker threads (ABA |
| 1182 | * problem). |
| 1183 | * For a single level, we logically remove and garbage collect each node. |
| 1184 | * |
| 1185 | * As a design choice, we perform logical removal and garbage collection on a |
| 1186 | * node-per-node basis to simplify this algorithm. We also assume keeping good |
| 1187 | * cache locality of the operation would overweight possible performance gain |
| 1188 | * that could be achieved by batching garbage collection for multiple levels. |
| 1189 | * However, this would have to be justified by benchmarks. |
| 1190 | * |
| 1191 | * Concurrent removal and add operations are helping us perform garbage |
| 1192 | * collection of logically removed nodes. We guarantee that all logically |
| 1193 | * removed nodes have been garbage-collected (unlinked) before call_rcu is |
| 1194 | * invoked to free a hole level of bucket nodes (after a grace period). |
| 1195 | * |
| 1196 | * Logical removal and garbage collection can therefore be done in batch or on a |
| 1197 | * node-per-node basis, as long as the guarantee above holds. |
| 1198 | * |
| 1199 | * When we reach a certain length, we can split this removal over many worker |
| 1200 | * threads, based on the number of CPUs available in the system. This should |
| 1201 | * take care of not letting resize process lag behind too many concurrent |
| 1202 | * updater threads actively inserting into the hash table. |
| 1203 | */ |
| 1204 | static |
| 1205 | void remove_table_partition(struct cds_lfht *ht, unsigned long i, |
| 1206 | unsigned long start, unsigned long len) |
| 1207 | { |
| 1208 | unsigned long j; |
| 1209 | |
| 1210 | assert(i > ht->min_alloc_order); |
| 1211 | ht->cds_lfht_rcu_read_lock(); |
| 1212 | for (j = start; j < start + len; j++) { |
| 1213 | struct cds_lfht_node *fini_node = &ht->t.tbl[i]->nodes[j]; |
| 1214 | |
| 1215 | dbg_printf("remove entry: i %lu j %lu hash %lu\n", |
| 1216 | i, j, (1UL << (i - 1)) + j); |
| 1217 | fini_node->reverse_hash = |
| 1218 | bit_reverse_ulong((1UL << (i - 1)) + j); |
| 1219 | (void) _cds_lfht_del(ht, 1UL << (i - 1), fini_node, 1); |
| 1220 | } |
| 1221 | ht->cds_lfht_rcu_read_unlock(); |
| 1222 | } |
| 1223 | |
| 1224 | static |
| 1225 | void remove_table(struct cds_lfht *ht, unsigned long i, unsigned long len) |
| 1226 | { |
| 1227 | |
| 1228 | assert(nr_cpus_mask != -1); |
| 1229 | if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) { |
| 1230 | ht->cds_lfht_rcu_thread_online(); |
| 1231 | remove_table_partition(ht, i, 0, len); |
| 1232 | ht->cds_lfht_rcu_thread_offline(); |
| 1233 | return; |
| 1234 | } |
| 1235 | partition_resize_helper(ht, i, len, remove_table_partition); |
| 1236 | } |
| 1237 | |
| 1238 | static |
| 1239 | void fini_table(struct cds_lfht *ht, |
| 1240 | unsigned long first_order, unsigned long last_order) |
| 1241 | { |
| 1242 | long i; |
| 1243 | void *free_by_rcu = NULL; |
| 1244 | |
| 1245 | dbg_printf("fini table: first_order %lu last_order %lu\n", |
| 1246 | first_order, last_order); |
| 1247 | assert(first_order > ht->min_alloc_order); |
| 1248 | for (i = last_order; i >= first_order; i--) { |
| 1249 | unsigned long len; |
| 1250 | |
| 1251 | len = 1UL << (i - 1); |
| 1252 | dbg_printf("fini order %lu len: %lu\n", i, len); |
| 1253 | |
| 1254 | /* Stop shrink if the resize target changes under us */ |
| 1255 | if (CMM_LOAD_SHARED(ht->t.resize_target) > (1UL << (i - 1))) |
| 1256 | break; |
| 1257 | |
| 1258 | cmm_smp_wmb(); /* populate data before RCU size */ |
| 1259 | CMM_STORE_SHARED(ht->t.size, 1UL << (i - 1)); |
| 1260 | |
| 1261 | /* |
| 1262 | * We need to wait for all add operations to reach Q.S. (and |
| 1263 | * thus use the new table for lookups) before we can start |
| 1264 | * releasing the old bucket nodes. Otherwise their lookup will |
| 1265 | * return a logically removed node as insert position. |
| 1266 | */ |
| 1267 | ht->cds_lfht_synchronize_rcu(); |
| 1268 | if (free_by_rcu) |
| 1269 | free(free_by_rcu); |
| 1270 | |
| 1271 | /* |
| 1272 | * Set "removed" flag in bucket nodes about to be removed. |
| 1273 | * Unlink all now-logically-removed bucket node pointers. |
| 1274 | * Concurrent add/remove operation are helping us doing |
| 1275 | * the gc. |
| 1276 | */ |
| 1277 | remove_table(ht, i, len); |
| 1278 | |
| 1279 | free_by_rcu = ht->t.tbl[i]; |
| 1280 | |
| 1281 | dbg_printf("fini new size: %lu\n", 1UL << i); |
| 1282 | if (CMM_LOAD_SHARED(ht->in_progress_destroy)) |
| 1283 | break; |
| 1284 | } |
| 1285 | |
| 1286 | if (free_by_rcu) { |
| 1287 | ht->cds_lfht_synchronize_rcu(); |
| 1288 | free(free_by_rcu); |
| 1289 | } |
| 1290 | } |
| 1291 | |
| 1292 | static |
| 1293 | void cds_lfht_create_bucket(struct cds_lfht *ht, unsigned long size) |
| 1294 | { |
| 1295 | struct cds_lfht_node *prev, *node; |
| 1296 | unsigned long order, len, i, j; |
| 1297 | |
| 1298 | ht->t.tbl[0] = calloc(1, ht->min_alloc_size * sizeof(struct cds_lfht_node)); |
| 1299 | assert(ht->t.tbl[0]); |
| 1300 | |
| 1301 | dbg_printf("create bucket: order %lu index %lu hash %lu\n", 0, 0, 0); |
| 1302 | ht->t.tbl[0]->nodes[0].next = flag_bucket(get_end()); |
| 1303 | ht->t.tbl[0]->nodes[0].reverse_hash = 0; |
| 1304 | |
| 1305 | for (order = 1; order < get_count_order_ulong(size) + 1; order++) { |
| 1306 | len = 1UL << (order - 1); |
| 1307 | if (order <= ht->min_alloc_order) { |
| 1308 | ht->t.tbl[order] = (struct rcu_level *) (ht->t.tbl[0]->nodes + len); |
| 1309 | } else { |
| 1310 | ht->t.tbl[order] = calloc(1, len * sizeof(struct cds_lfht_node)); |
| 1311 | assert(ht->t.tbl[order]); |
| 1312 | } |
| 1313 | |
| 1314 | i = 0; |
| 1315 | prev = ht->t.tbl[i]->nodes; |
| 1316 | for (j = 0; j < len; j++) { |
| 1317 | if (j & (j - 1)) { /* Between power of 2 */ |
| 1318 | prev++; |
| 1319 | } else if (j) { /* At each power of 2 */ |
| 1320 | i++; |
| 1321 | prev = ht->t.tbl[i]->nodes; |
| 1322 | } |
| 1323 | |
| 1324 | node = &ht->t.tbl[order]->nodes[j]; |
| 1325 | dbg_printf("create bucket: order %lu index %lu hash %lu\n", |
| 1326 | order, j, j + len); |
| 1327 | node->next = prev->next; |
| 1328 | assert(is_bucket(node->next)); |
| 1329 | node->reverse_hash = bit_reverse_ulong(j + len); |
| 1330 | prev->next = flag_bucket(node); |
| 1331 | } |
| 1332 | } |
| 1333 | } |
| 1334 | |
| 1335 | struct cds_lfht *_cds_lfht_new(unsigned long init_size, |
| 1336 | unsigned long min_alloc_size, |
| 1337 | int flags, |
| 1338 | void (*cds_lfht_call_rcu)(struct rcu_head *head, |
| 1339 | void (*func)(struct rcu_head *head)), |
| 1340 | void (*cds_lfht_synchronize_rcu)(void), |
| 1341 | void (*cds_lfht_rcu_read_lock)(void), |
| 1342 | void (*cds_lfht_rcu_read_unlock)(void), |
| 1343 | void (*cds_lfht_rcu_thread_offline)(void), |
| 1344 | void (*cds_lfht_rcu_thread_online)(void), |
| 1345 | void (*cds_lfht_rcu_register_thread)(void), |
| 1346 | void (*cds_lfht_rcu_unregister_thread)(void), |
| 1347 | pthread_attr_t *attr) |
| 1348 | { |
| 1349 | struct cds_lfht *ht; |
| 1350 | unsigned long order; |
| 1351 | |
| 1352 | /* min_alloc_size must be power of two */ |
| 1353 | if (!min_alloc_size || (min_alloc_size & (min_alloc_size - 1))) |
| 1354 | return NULL; |
| 1355 | /* init_size must be power of two */ |
| 1356 | if (!init_size || (init_size & (init_size - 1))) |
| 1357 | return NULL; |
| 1358 | min_alloc_size = max(min_alloc_size, MIN_TABLE_SIZE); |
| 1359 | init_size = max(init_size, min_alloc_size); |
| 1360 | ht = calloc(1, sizeof(struct cds_lfht)); |
| 1361 | assert(ht); |
| 1362 | ht->flags = flags; |
| 1363 | ht->cds_lfht_call_rcu = cds_lfht_call_rcu; |
| 1364 | ht->cds_lfht_synchronize_rcu = cds_lfht_synchronize_rcu; |
| 1365 | ht->cds_lfht_rcu_read_lock = cds_lfht_rcu_read_lock; |
| 1366 | ht->cds_lfht_rcu_read_unlock = cds_lfht_rcu_read_unlock; |
| 1367 | ht->cds_lfht_rcu_thread_offline = cds_lfht_rcu_thread_offline; |
| 1368 | ht->cds_lfht_rcu_thread_online = cds_lfht_rcu_thread_online; |
| 1369 | ht->cds_lfht_rcu_register_thread = cds_lfht_rcu_register_thread; |
| 1370 | ht->cds_lfht_rcu_unregister_thread = cds_lfht_rcu_unregister_thread; |
| 1371 | ht->resize_attr = attr; |
| 1372 | alloc_split_items_count(ht); |
| 1373 | /* this mutex should not nest in read-side C.S. */ |
| 1374 | pthread_mutex_init(&ht->resize_mutex, NULL); |
| 1375 | order = get_count_order_ulong(init_size); |
| 1376 | ht->t.resize_target = 1UL << order; |
| 1377 | ht->min_alloc_size = min_alloc_size; |
| 1378 | ht->min_alloc_order = get_count_order_ulong(min_alloc_size); |
| 1379 | cds_lfht_create_bucket(ht, 1UL << order); |
| 1380 | ht->t.size = 1UL << order; |
| 1381 | return ht; |
| 1382 | } |
| 1383 | |
| 1384 | void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash, |
| 1385 | cds_lfht_match_fct match, const void *key, |
| 1386 | struct cds_lfht_iter *iter) |
| 1387 | { |
| 1388 | struct cds_lfht_node *node, *next, *bucket; |
| 1389 | unsigned long reverse_hash, size; |
| 1390 | |
| 1391 | reverse_hash = bit_reverse_ulong(hash); |
| 1392 | |
| 1393 | size = rcu_dereference(ht->t.size); |
| 1394 | bucket = lookup_bucket(ht, size, hash); |
| 1395 | /* We can always skip the bucket node initially */ |
| 1396 | node = rcu_dereference(bucket->next); |
| 1397 | node = clear_flag(node); |
| 1398 | for (;;) { |
| 1399 | if (caa_unlikely(is_end(node))) { |
| 1400 | node = next = NULL; |
| 1401 | break; |
| 1402 | } |
| 1403 | if (caa_unlikely(node->reverse_hash > reverse_hash)) { |
| 1404 | node = next = NULL; |
| 1405 | break; |
| 1406 | } |
| 1407 | next = rcu_dereference(node->next); |
| 1408 | assert(node == clear_flag(node)); |
| 1409 | if (caa_likely(!is_removed(next)) |
| 1410 | && !is_bucket(next) |
| 1411 | && node->reverse_hash == reverse_hash |
| 1412 | && caa_likely(match(node, key))) { |
| 1413 | break; |
| 1414 | } |
| 1415 | node = clear_flag(next); |
| 1416 | } |
| 1417 | assert(!node || !is_bucket(rcu_dereference(node->next))); |
| 1418 | iter->node = node; |
| 1419 | iter->next = next; |
| 1420 | } |
| 1421 | |
| 1422 | void cds_lfht_next_duplicate(struct cds_lfht *ht, cds_lfht_match_fct match, |
| 1423 | const void *key, struct cds_lfht_iter *iter) |
| 1424 | { |
| 1425 | struct cds_lfht_node *node, *next; |
| 1426 | unsigned long reverse_hash; |
| 1427 | |
| 1428 | node = iter->node; |
| 1429 | reverse_hash = node->reverse_hash; |
| 1430 | next = iter->next; |
| 1431 | node = clear_flag(next); |
| 1432 | |
| 1433 | for (;;) { |
| 1434 | if (caa_unlikely(is_end(node))) { |
| 1435 | node = next = NULL; |
| 1436 | break; |
| 1437 | } |
| 1438 | if (caa_unlikely(node->reverse_hash > reverse_hash)) { |
| 1439 | node = next = NULL; |
| 1440 | break; |
| 1441 | } |
| 1442 | next = rcu_dereference(node->next); |
| 1443 | if (caa_likely(!is_removed(next)) |
| 1444 | && !is_bucket(next) |
| 1445 | && caa_likely(match(node, key))) { |
| 1446 | break; |
| 1447 | } |
| 1448 | node = clear_flag(next); |
| 1449 | } |
| 1450 | assert(!node || !is_bucket(rcu_dereference(node->next))); |
| 1451 | iter->node = node; |
| 1452 | iter->next = next; |
| 1453 | } |
| 1454 | |
| 1455 | void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter) |
| 1456 | { |
| 1457 | struct cds_lfht_node *node, *next; |
| 1458 | |
| 1459 | node = clear_flag(iter->next); |
| 1460 | for (;;) { |
| 1461 | if (caa_unlikely(is_end(node))) { |
| 1462 | node = next = NULL; |
| 1463 | break; |
| 1464 | } |
| 1465 | next = rcu_dereference(node->next); |
| 1466 | if (caa_likely(!is_removed(next)) |
| 1467 | && !is_bucket(next)) { |
| 1468 | break; |
| 1469 | } |
| 1470 | node = clear_flag(next); |
| 1471 | } |
| 1472 | assert(!node || !is_bucket(rcu_dereference(node->next))); |
| 1473 | iter->node = node; |
| 1474 | iter->next = next; |
| 1475 | } |
| 1476 | |
| 1477 | void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter) |
| 1478 | { |
| 1479 | struct cds_lfht_node *lookup; |
| 1480 | |
| 1481 | /* |
| 1482 | * Get next after first bucket node. The first bucket node is the |
| 1483 | * first node of the linked list. |
| 1484 | */ |
| 1485 | lookup = &ht->t.tbl[0]->nodes[0]; |
| 1486 | iter->next = lookup->next; |
| 1487 | cds_lfht_next(ht, iter); |
| 1488 | } |
| 1489 | |
| 1490 | void cds_lfht_add(struct cds_lfht *ht, unsigned long hash, |
| 1491 | struct cds_lfht_node *node) |
| 1492 | { |
| 1493 | unsigned long size; |
| 1494 | |
| 1495 | node->reverse_hash = bit_reverse_ulong((unsigned long) hash); |
| 1496 | size = rcu_dereference(ht->t.size); |
| 1497 | _cds_lfht_add(ht, NULL, NULL, size, node, NULL, 0); |
| 1498 | ht_count_add(ht, size, hash); |
| 1499 | } |
| 1500 | |
| 1501 | struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, |
| 1502 | unsigned long hash, |
| 1503 | cds_lfht_match_fct match, |
| 1504 | const void *key, |
| 1505 | struct cds_lfht_node *node) |
| 1506 | { |
| 1507 | unsigned long size; |
| 1508 | struct cds_lfht_iter iter; |
| 1509 | |
| 1510 | node->reverse_hash = bit_reverse_ulong((unsigned long) hash); |
| 1511 | size = rcu_dereference(ht->t.size); |
| 1512 | _cds_lfht_add(ht, match, key, size, node, &iter, 0); |
| 1513 | if (iter.node == node) |
| 1514 | ht_count_add(ht, size, hash); |
| 1515 | return iter.node; |
| 1516 | } |
| 1517 | |
| 1518 | struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht, |
| 1519 | unsigned long hash, |
| 1520 | cds_lfht_match_fct match, |
| 1521 | const void *key, |
| 1522 | struct cds_lfht_node *node) |
| 1523 | { |
| 1524 | unsigned long size; |
| 1525 | struct cds_lfht_iter iter; |
| 1526 | |
| 1527 | node->reverse_hash = bit_reverse_ulong((unsigned long) hash); |
| 1528 | size = rcu_dereference(ht->t.size); |
| 1529 | for (;;) { |
| 1530 | _cds_lfht_add(ht, match, key, size, node, &iter, 0); |
| 1531 | if (iter.node == node) { |
| 1532 | ht_count_add(ht, size, hash); |
| 1533 | return NULL; |
| 1534 | } |
| 1535 | |
| 1536 | if (!_cds_lfht_replace(ht, size, iter.node, iter.next, node)) |
| 1537 | return iter.node; |
| 1538 | } |
| 1539 | } |
| 1540 | |
| 1541 | int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter, |
| 1542 | struct cds_lfht_node *new_node) |
| 1543 | { |
| 1544 | unsigned long size; |
| 1545 | |
| 1546 | size = rcu_dereference(ht->t.size); |
| 1547 | return _cds_lfht_replace(ht, size, old_iter->node, old_iter->next, |
| 1548 | new_node); |
| 1549 | } |
| 1550 | |
| 1551 | int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_iter *iter) |
| 1552 | { |
| 1553 | unsigned long size, hash; |
| 1554 | int ret; |
| 1555 | |
| 1556 | size = rcu_dereference(ht->t.size); |
| 1557 | ret = _cds_lfht_del(ht, size, iter->node, 0); |
| 1558 | if (!ret) { |
| 1559 | hash = bit_reverse_ulong(iter->node->reverse_hash); |
| 1560 | ht_count_del(ht, size, hash); |
| 1561 | } |
| 1562 | return ret; |
| 1563 | } |
| 1564 | |
| 1565 | static |
| 1566 | int cds_lfht_delete_bucket(struct cds_lfht *ht) |
| 1567 | { |
| 1568 | struct cds_lfht_node *node; |
| 1569 | unsigned long order, i, size; |
| 1570 | |
| 1571 | /* Check that the table is empty */ |
| 1572 | node = &ht->t.tbl[0]->nodes[0]; |
| 1573 | do { |
| 1574 | node = clear_flag(node)->next; |
| 1575 | if (!is_bucket(node)) |
| 1576 | return -EPERM; |
| 1577 | assert(!is_removed(node)); |
| 1578 | } while (!is_end(node)); |
| 1579 | /* |
| 1580 | * size accessed without rcu_dereference because hash table is |
| 1581 | * being destroyed. |
| 1582 | */ |
| 1583 | size = ht->t.size; |
| 1584 | /* Internal sanity check: all nodes left should be bucket */ |
| 1585 | for (order = 0; order < get_count_order_ulong(size) + 1; order++) { |
| 1586 | unsigned long len; |
| 1587 | |
| 1588 | len = !order ? 1 : 1UL << (order - 1); |
| 1589 | for (i = 0; i < len; i++) { |
| 1590 | dbg_printf("delete order %lu i %lu hash %lu\n", |
| 1591 | order, i, |
| 1592 | bit_reverse_ulong(ht->t.tbl[order]->nodes[i].reverse_hash)); |
| 1593 | assert(is_bucket(ht->t.tbl[order]->nodes[i].next)); |
| 1594 | } |
| 1595 | |
| 1596 | if (order == ht->min_alloc_order) |
| 1597 | poison_free(ht->t.tbl[0]); |
| 1598 | else if (order > ht->min_alloc_order) |
| 1599 | poison_free(ht->t.tbl[order]); |
| 1600 | /* Nothing to delete for order < ht->min_alloc_order */ |
| 1601 | } |
| 1602 | return 0; |
| 1603 | } |
| 1604 | |
| 1605 | /* |
| 1606 | * Should only be called when no more concurrent readers nor writers can |
| 1607 | * possibly access the table. |
| 1608 | */ |
| 1609 | int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr) |
| 1610 | { |
| 1611 | int ret; |
| 1612 | |
| 1613 | /* Wait for in-flight resize operations to complete */ |
| 1614 | _CMM_STORE_SHARED(ht->in_progress_destroy, 1); |
| 1615 | cmm_smp_mb(); /* Store destroy before load resize */ |
| 1616 | while (uatomic_read(&ht->in_progress_resize)) |
| 1617 | poll(NULL, 0, 100); /* wait for 100ms */ |
| 1618 | ret = cds_lfht_delete_bucket(ht); |
| 1619 | if (ret) |
| 1620 | return ret; |
| 1621 | free_split_items_count(ht); |
| 1622 | if (attr) |
| 1623 | *attr = ht->resize_attr; |
| 1624 | poison_free(ht); |
| 1625 | return ret; |
| 1626 | } |
| 1627 | |
| 1628 | void cds_lfht_count_nodes(struct cds_lfht *ht, |
| 1629 | long *approx_before, |
| 1630 | unsigned long *count, |
| 1631 | unsigned long *removed, |
| 1632 | long *approx_after) |
| 1633 | { |
| 1634 | struct cds_lfht_node *node, *next; |
| 1635 | unsigned long nr_bucket = 0; |
| 1636 | |
| 1637 | *approx_before = 0; |
| 1638 | if (ht->split_count) { |
| 1639 | int i; |
| 1640 | |
| 1641 | for (i = 0; i < split_count_mask + 1; i++) { |
| 1642 | *approx_before += uatomic_read(&ht->split_count[i].add); |
| 1643 | *approx_before -= uatomic_read(&ht->split_count[i].del); |
| 1644 | } |
| 1645 | } |
| 1646 | |
| 1647 | *count = 0; |
| 1648 | *removed = 0; |
| 1649 | |
| 1650 | /* Count non-bucket nodes in the table */ |
| 1651 | node = &ht->t.tbl[0]->nodes[0]; |
| 1652 | do { |
| 1653 | next = rcu_dereference(node->next); |
| 1654 | if (is_removed(next)) { |
| 1655 | if (!is_bucket(next)) |
| 1656 | (*removed)++; |
| 1657 | else |
| 1658 | (nr_bucket)++; |
| 1659 | } else if (!is_bucket(next)) |
| 1660 | (*count)++; |
| 1661 | else |
| 1662 | (nr_bucket)++; |
| 1663 | node = clear_flag(next); |
| 1664 | } while (!is_end(node)); |
| 1665 | dbg_printf("number of bucket nodes: %lu\n", nr_bucket); |
| 1666 | *approx_after = 0; |
| 1667 | if (ht->split_count) { |
| 1668 | int i; |
| 1669 | |
| 1670 | for (i = 0; i < split_count_mask + 1; i++) { |
| 1671 | *approx_after += uatomic_read(&ht->split_count[i].add); |
| 1672 | *approx_after -= uatomic_read(&ht->split_count[i].del); |
| 1673 | } |
| 1674 | } |
| 1675 | } |
| 1676 | |
| 1677 | /* called with resize mutex held */ |
| 1678 | static |
| 1679 | void _do_cds_lfht_grow(struct cds_lfht *ht, |
| 1680 | unsigned long old_size, unsigned long new_size) |
| 1681 | { |
| 1682 | unsigned long old_order, new_order; |
| 1683 | |
| 1684 | old_order = get_count_order_ulong(old_size); |
| 1685 | new_order = get_count_order_ulong(new_size); |
| 1686 | dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", |
| 1687 | old_size, old_order, new_size, new_order); |
| 1688 | assert(new_size > old_size); |
| 1689 | init_table(ht, old_order + 1, new_order); |
| 1690 | } |
| 1691 | |
| 1692 | /* called with resize mutex held */ |
| 1693 | static |
| 1694 | void _do_cds_lfht_shrink(struct cds_lfht *ht, |
| 1695 | unsigned long old_size, unsigned long new_size) |
| 1696 | { |
| 1697 | unsigned long old_order, new_order; |
| 1698 | |
| 1699 | new_size = max(new_size, ht->min_alloc_size); |
| 1700 | old_order = get_count_order_ulong(old_size); |
| 1701 | new_order = get_count_order_ulong(new_size); |
| 1702 | dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", |
| 1703 | old_size, old_order, new_size, new_order); |
| 1704 | assert(new_size < old_size); |
| 1705 | |
| 1706 | /* Remove and unlink all bucket nodes to remove. */ |
| 1707 | fini_table(ht, new_order + 1, old_order); |
| 1708 | } |
| 1709 | |
| 1710 | |
| 1711 | /* called with resize mutex held */ |
| 1712 | static |
| 1713 | void _do_cds_lfht_resize(struct cds_lfht *ht) |
| 1714 | { |
| 1715 | unsigned long new_size, old_size; |
| 1716 | |
| 1717 | /* |
| 1718 | * Resize table, re-do if the target size has changed under us. |
| 1719 | */ |
| 1720 | do { |
| 1721 | assert(uatomic_read(&ht->in_progress_resize)); |
| 1722 | if (CMM_LOAD_SHARED(ht->in_progress_destroy)) |
| 1723 | break; |
| 1724 | ht->t.resize_initiated = 1; |
| 1725 | old_size = ht->t.size; |
| 1726 | new_size = CMM_LOAD_SHARED(ht->t.resize_target); |
| 1727 | if (old_size < new_size) |
| 1728 | _do_cds_lfht_grow(ht, old_size, new_size); |
| 1729 | else if (old_size > new_size) |
| 1730 | _do_cds_lfht_shrink(ht, old_size, new_size); |
| 1731 | ht->t.resize_initiated = 0; |
| 1732 | /* write resize_initiated before read resize_target */ |
| 1733 | cmm_smp_mb(); |
| 1734 | } while (ht->t.size != CMM_LOAD_SHARED(ht->t.resize_target)); |
| 1735 | } |
| 1736 | |
| 1737 | static |
| 1738 | unsigned long resize_target_grow(struct cds_lfht *ht, unsigned long new_size) |
| 1739 | { |
| 1740 | return _uatomic_xchg_monotonic_increase(&ht->t.resize_target, new_size); |
| 1741 | } |
| 1742 | |
| 1743 | static |
| 1744 | void resize_target_update_count(struct cds_lfht *ht, |
| 1745 | unsigned long count) |
| 1746 | { |
| 1747 | count = max(count, ht->min_alloc_size); |
| 1748 | uatomic_set(&ht->t.resize_target, count); |
| 1749 | } |
| 1750 | |
| 1751 | void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size) |
| 1752 | { |
| 1753 | resize_target_update_count(ht, new_size); |
| 1754 | CMM_STORE_SHARED(ht->t.resize_initiated, 1); |
| 1755 | ht->cds_lfht_rcu_thread_offline(); |
| 1756 | pthread_mutex_lock(&ht->resize_mutex); |
| 1757 | _do_cds_lfht_resize(ht); |
| 1758 | pthread_mutex_unlock(&ht->resize_mutex); |
| 1759 | ht->cds_lfht_rcu_thread_online(); |
| 1760 | } |
| 1761 | |
| 1762 | static |
| 1763 | void do_resize_cb(struct rcu_head *head) |
| 1764 | { |
| 1765 | struct rcu_resize_work *work = |
| 1766 | caa_container_of(head, struct rcu_resize_work, head); |
| 1767 | struct cds_lfht *ht = work->ht; |
| 1768 | |
| 1769 | ht->cds_lfht_rcu_thread_offline(); |
| 1770 | pthread_mutex_lock(&ht->resize_mutex); |
| 1771 | _do_cds_lfht_resize(ht); |
| 1772 | pthread_mutex_unlock(&ht->resize_mutex); |
| 1773 | ht->cds_lfht_rcu_thread_online(); |
| 1774 | poison_free(work); |
| 1775 | cmm_smp_mb(); /* finish resize before decrement */ |
| 1776 | uatomic_dec(&ht->in_progress_resize); |
| 1777 | } |
| 1778 | |
| 1779 | static |
| 1780 | void __cds_lfht_resize_lazy_launch(struct cds_lfht *ht) |
| 1781 | { |
| 1782 | struct rcu_resize_work *work; |
| 1783 | |
| 1784 | /* Store resize_target before read resize_initiated */ |
| 1785 | cmm_smp_mb(); |
| 1786 | if (!CMM_LOAD_SHARED(ht->t.resize_initiated)) { |
| 1787 | uatomic_inc(&ht->in_progress_resize); |
| 1788 | cmm_smp_mb(); /* increment resize count before load destroy */ |
| 1789 | if (CMM_LOAD_SHARED(ht->in_progress_destroy)) { |
| 1790 | uatomic_dec(&ht->in_progress_resize); |
| 1791 | return; |
| 1792 | } |
| 1793 | work = malloc(sizeof(*work)); |
| 1794 | work->ht = ht; |
| 1795 | ht->cds_lfht_call_rcu(&work->head, do_resize_cb); |
| 1796 | CMM_STORE_SHARED(ht->t.resize_initiated, 1); |
| 1797 | } |
| 1798 | } |
| 1799 | |
| 1800 | static |
| 1801 | void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth) |
| 1802 | { |
| 1803 | unsigned long target_size = size << growth; |
| 1804 | |
| 1805 | if (resize_target_grow(ht, target_size) >= target_size) |
| 1806 | return; |
| 1807 | |
| 1808 | __cds_lfht_resize_lazy_launch(ht); |
| 1809 | } |
| 1810 | |
| 1811 | /* |
| 1812 | * We favor grow operations over shrink. A shrink operation never occurs |
| 1813 | * if a grow operation is queued for lazy execution. A grow operation |
| 1814 | * cancels any pending shrink lazy execution. |
| 1815 | */ |
| 1816 | static |
| 1817 | void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size, |
| 1818 | unsigned long count) |
| 1819 | { |
| 1820 | if (!(ht->flags & CDS_LFHT_AUTO_RESIZE)) |
| 1821 | return; |
| 1822 | count = max(count, ht->min_alloc_size); |
| 1823 | if (count == size) |
| 1824 | return; /* Already the right size, no resize needed */ |
| 1825 | if (count > size) { /* lazy grow */ |
| 1826 | if (resize_target_grow(ht, count) >= count) |
| 1827 | return; |
| 1828 | } else { /* lazy shrink */ |
| 1829 | for (;;) { |
| 1830 | unsigned long s; |
| 1831 | |
| 1832 | s = uatomic_cmpxchg(&ht->t.resize_target, size, count); |
| 1833 | if (s == size) |
| 1834 | break; /* no resize needed */ |
| 1835 | if (s > size) |
| 1836 | return; /* growing is/(was just) in progress */ |
| 1837 | if (s <= count) |
| 1838 | return; /* some other thread do shrink */ |
| 1839 | size = s; |
| 1840 | } |
| 1841 | } |
| 1842 | __cds_lfht_resize_lazy_launch(ht); |
| 1843 | } |