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