X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=liblttng-ht%2Frculfhash.c;fp=liblttng-ht%2Frculfhash.c;h=0000000000000000000000000000000000000000;hp=840de351bcf83f616116e4d4b937201505eecd4b;hb=10a8a2237343699e3923d87e24dbf2d7fe225377;hpb=734f79bf717d87817623d382c59086dc9e8ef610 diff --git a/liblttng-ht/rculfhash.c b/liblttng-ht/rculfhash.c deleted file mode 100644 index 840de351b..000000000 --- a/liblttng-ht/rculfhash.c +++ /dev/null @@ -1,1832 +0,0 @@ -/* - * rculfhash.c - * - * Userspace RCU library - Lock-Free Resizable RCU Hash Table - * - * Copyright 2010-2011 - Mathieu Desnoyers - * Copyright 2011 - Lai Jiangshan - * - * This library is free software; you can redistribute it and/or - * modify it under the terms of the GNU Lesser General Public - * License as published by the Free Software Foundation; either - * version 2.1 of the License, or (at your option) any later version. - * - * This library is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * Lesser General Public License for more details. - * - * You should have received a copy of the GNU Lesser General Public - * License along with this library; if not, write to the Free Software - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA - */ - -/* - * Based on the following articles: - * - Ori Shalev and Nir Shavit. Split-ordered lists: Lock-free - * extensible hash tables. J. ACM 53, 3 (May 2006), 379-405. - * - Michael, M. M. High performance dynamic lock-free hash tables - * and list-based sets. In Proceedings of the fourteenth annual ACM - * symposium on Parallel algorithms and architectures, ACM Press, - * (2002), 73-82. - * - * Some specificities of this Lock-Free Resizable RCU Hash Table - * implementation: - * - * - RCU read-side critical section allows readers to perform hash - * table lookups and use the returned objects safely by delaying - * memory reclaim of a grace period. - * - Add and remove operations are lock-free, and do not need to - * allocate memory. They need to be executed within RCU read-side - * critical section to ensure the objects they read are valid and to - * deal with the cmpxchg ABA problem. - * - add and add_unique operations are supported. add_unique checks if - * the node key already exists in the hash table. It ensures no key - * duplicata exists. - * - The resize operation executes concurrently with add/remove/lookup. - * - Hash table nodes are contained within a split-ordered list. This - * list is ordered by incrementing reversed-bits-hash value. - * - An index of bucket nodes is kept. These bucket nodes are the hash - * table "buckets", and they are also chained together in the - * split-ordered list, which allows recursive expansion. - * - The resize operation for small tables only allows expanding the hash table. - * It is triggered automatically by detecting long chains in the add - * operation. - * - The resize operation for larger tables (and available through an - * API) allows both expanding and shrinking the hash table. - * - Split-counters are used to keep track of the number of - * nodes within the hash table for automatic resize triggering. - * - Resize operation initiated by long chain detection is executed by a - * call_rcu thread, which keeps lock-freedom of add and remove. - * - Resize operations are protected by a mutex. - * - The removal operation is split in two parts: first, a "removed" - * flag is set in the next pointer within the node to remove. Then, - * a "garbage collection" is performed in the bucket containing the - * removed node (from the start of the bucket up to the removed node). - * All encountered nodes with "removed" flag set in their next - * pointers are removed from the linked-list. If the cmpxchg used for - * removal fails (due to concurrent garbage-collection or concurrent - * add), we retry from the beginning of the bucket. This ensures that - * the node with "removed" flag set is removed from the hash table - * (not visible to lookups anymore) before the RCU read-side critical - * section held across removal ends. Furthermore, this ensures that - * the node with "removed" flag set is removed from the linked-list - * before its memory is reclaimed. Only the thread which removal - * successfully set the "removed" flag (with a cmpxchg) into a node's - * next pointer is considered to have succeeded its removal (and thus - * owns the node to reclaim). Because we garbage-collect starting from - * an invariant node (the start-of-bucket bucket node) up to the - * "removed" node (or find a reverse-hash that is higher), we are sure - * that a successful traversal of the chain leads to a chain that is - * present in the linked-list (the start node is never removed) and - * that is does not contain the "removed" node anymore, even if - * concurrent delete/add operations are changing the structure of the - * list concurrently. - * - The add operation performs gargage collection of buckets if it - * encounters nodes with removed flag set in the bucket where it wants - * to add its new node. This ensures lock-freedom of add operation by - * helping the remover unlink nodes from the list rather than to wait - * for it do to so. - * - A RCU "order table" indexed by log2(hash index) is copied and - * expanded by the resize operation. This order table allows finding - * the "bucket node" tables. - * - There is one bucket node table per hash index order. The size of - * each bucket node table is half the number of hashes contained in - * this order (except for order 0). - * - synchronzie_rcu is used to garbage-collect the old bucket node table. - * - The per-order bucket node tables contain a compact version of the - * hash table nodes. These tables are invariant after they are - * populated into the hash table. - * - * Bucket node tables: - * - * hash table hash table the last all bucket node tables - * order size bucket node 0 1 2 3 4 5 6(index) - * table size - * 0 1 1 1 - * 1 2 1 1 1 - * 2 4 2 1 1 2 - * 3 8 4 1 1 2 4 - * 4 16 8 1 1 2 4 8 - * 5 32 16 1 1 2 4 8 16 - * 6 64 32 1 1 2 4 8 16 32 - * - * When growing/shrinking, we only focus on the last bucket node table - * which size is (!order ? 1 : (1 << (order -1))). - * - * Example for growing/shrinking: - * grow hash table from order 5 to 6: init the index=6 bucket node table - * shrink hash table from order 6 to 5: fini the index=6 bucket node table - * - * A bit of ascii art explanation: - * - * Order index is the off-by-one compare to the actual power of 2 because - * we use index 0 to deal with the 0 special-case. - * - * This shows the nodes for a small table ordered by reversed bits: - * - * bits reverse - * 0 000 000 - * 4 100 001 - * 2 010 010 - * 6 110 011 - * 1 001 100 - * 5 101 101 - * 3 011 110 - * 7 111 111 - * - * This shows the nodes in order of non-reversed bits, linked by - * reversed-bit order. - * - * order bits reverse - * 0 0 000 000 - * 1 | 1 001 100 <- - * 2 | | 2 010 010 <- | - * | | | 3 011 110 | <- | - * 3 -> | | | 4 100 001 | | - * -> | | 5 101 101 | - * -> | 6 110 011 - * -> 7 111 111 - */ - -#define _LGPL_SOURCE -#include -#include -#include -#include -#include -#include - -#include "config.h" -#include -#include -#include -#include -#include -#include -#include - -#include "rculfhash.h" -#include "rculfhash-internal.h" -#include "urcu-flavor.h" - -/* - * Split-counters lazily update the global counter each 1024 - * addition/removal. It automatically keeps track of resize required. - * We use the bucket length as indicator for need to expand for small - * tables and machines lacking per-cpu data suppport. - */ -#define COUNT_COMMIT_ORDER 10 -#define DEFAULT_SPLIT_COUNT_MASK 0xFUL -#define CHAIN_LEN_TARGET 1 -#define CHAIN_LEN_RESIZE_THRESHOLD 3 - -/* - * Define the minimum table size. - */ -#define MIN_TABLE_ORDER 0 -#define MIN_TABLE_SIZE (1UL << MIN_TABLE_ORDER) - -/* - * Minimum number of bucket nodes to touch per thread to parallelize grow/shrink. - */ -#define MIN_PARTITION_PER_THREAD_ORDER 12 -#define MIN_PARTITION_PER_THREAD (1UL << MIN_PARTITION_PER_THREAD_ORDER) - -/* - * The removed flag needs to be updated atomically with the pointer. - * It indicates that no node must attach to the node scheduled for - * removal, and that node garbage collection must be performed. - * The bucket flag does not require to be updated atomically with the - * pointer, but it is added as a pointer low bit flag to save space. - */ -#define REMOVED_FLAG (1UL << 0) -#define BUCKET_FLAG (1UL << 1) -#define REMOVAL_OWNER_FLAG (1UL << 2) -#define FLAGS_MASK ((1UL << 3) - 1) - -/* Value of the end pointer. Should not interact with flags. */ -#define END_VALUE NULL - -DEFINE_RCU_FLAVOR(rcu_flavor); - -/* - * ht_items_count: Split-counters counting the number of node addition - * and removal in the table. Only used if the CDS_LFHT_ACCOUNTING flag - * is set at hash table creation. - * - * These are free-running counters, never reset to zero. They count the - * number of add/remove, and trigger every (1 << COUNT_COMMIT_ORDER) - * operations to update the global counter. We choose a power-of-2 value - * for the trigger to deal with 32 or 64-bit overflow of the counter. - */ -struct ht_items_count { - unsigned long add, del; -} __attribute__((aligned(CAA_CACHE_LINE_SIZE))); - -/* - * rcu_resize_work: Contains arguments passed to RCU worker thread - * responsible for performing lazy resize. - */ -struct rcu_resize_work { - struct rcu_head head; - struct cds_lfht *ht; -}; - -/* - * partition_resize_work: Contains arguments passed to worker threads - * executing the hash table resize on partitions of the hash table - * assigned to each processor's worker thread. - */ -struct partition_resize_work { - pthread_t thread_id; - struct cds_lfht *ht; - unsigned long i, start, len; - void (*fct)(struct cds_lfht *ht, unsigned long i, - unsigned long start, unsigned long len); -}; - -/* - * Algorithm to reverse bits in a word by lookup table, extended to - * 64-bit words. - * Source: - * http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable - * Originally from Public Domain. - */ - -static const uint8_t BitReverseTable256[256] = -{ -#define R2(n) (n), (n) + 2*64, (n) + 1*64, (n) + 3*64 -#define R4(n) R2(n), R2((n) + 2*16), R2((n) + 1*16), R2((n) + 3*16) -#define R6(n) R4(n), R4((n) + 2*4 ), R4((n) + 1*4 ), R4((n) + 3*4 ) - R6(0), R6(2), R6(1), R6(3) -}; -#undef R2 -#undef R4 -#undef R6 - -static -uint8_t bit_reverse_u8(uint8_t v) -{ - return BitReverseTable256[v]; -} - -static __attribute__((unused)) -uint32_t bit_reverse_u32(uint32_t v) -{ - return ((uint32_t) bit_reverse_u8(v) << 24) | - ((uint32_t) bit_reverse_u8(v >> 8) << 16) | - ((uint32_t) bit_reverse_u8(v >> 16) << 8) | - ((uint32_t) bit_reverse_u8(v >> 24)); -} - -static __attribute__((unused)) -uint64_t bit_reverse_u64(uint64_t v) -{ - return ((uint64_t) bit_reverse_u8(v) << 56) | - ((uint64_t) bit_reverse_u8(v >> 8) << 48) | - ((uint64_t) bit_reverse_u8(v >> 16) << 40) | - ((uint64_t) bit_reverse_u8(v >> 24) << 32) | - ((uint64_t) bit_reverse_u8(v >> 32) << 24) | - ((uint64_t) bit_reverse_u8(v >> 40) << 16) | - ((uint64_t) bit_reverse_u8(v >> 48) << 8) | - ((uint64_t) bit_reverse_u8(v >> 56)); -} - -static -unsigned long bit_reverse_ulong(unsigned long v) -{ -#if (CAA_BITS_PER_LONG == 32) - return bit_reverse_u32(v); -#else - return bit_reverse_u64(v); -#endif -} - -/* - * fls: returns the position of the most significant bit. - * Returns 0 if no bit is set, else returns the position of the most - * significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit). - */ -#if defined(__i386) || defined(__x86_64) -static inline -unsigned int fls_u32(uint32_t x) -{ - int r; - - asm("bsrl %1,%0\n\t" - "jnz 1f\n\t" - "movl $-1,%0\n\t" - "1:\n\t" - : "=r" (r) : "rm" (x)); - return r + 1; -} -#define HAS_FLS_U32 -#endif - -#if defined(__x86_64) -static inline -unsigned int fls_u64(uint64_t x) -{ - long r; - - asm("bsrq %1,%0\n\t" - "jnz 1f\n\t" - "movq $-1,%0\n\t" - "1:\n\t" - : "=r" (r) : "rm" (x)); - return r + 1; -} -#define HAS_FLS_U64 -#endif - -#ifndef HAS_FLS_U64 -static __attribute__((unused)) -unsigned int fls_u64(uint64_t x) -{ - unsigned int r = 64; - - if (!x) - return 0; - - if (!(x & 0xFFFFFFFF00000000ULL)) { - x <<= 32; - r -= 32; - } - if (!(x & 0xFFFF000000000000ULL)) { - x <<= 16; - r -= 16; - } - if (!(x & 0xFF00000000000000ULL)) { - x <<= 8; - r -= 8; - } - if (!(x & 0xF000000000000000ULL)) { - x <<= 4; - r -= 4; - } - if (!(x & 0xC000000000000000ULL)) { - x <<= 2; - r -= 2; - } - if (!(x & 0x8000000000000000ULL)) { - x <<= 1; - r -= 1; - } - return r; -} -#endif - -#ifndef HAS_FLS_U32 -static __attribute__((unused)) -unsigned int fls_u32(uint32_t x) -{ - unsigned int r = 32; - - if (!x) - return 0; - if (!(x & 0xFFFF0000U)) { - x <<= 16; - r -= 16; - } - if (!(x & 0xFF000000U)) { - x <<= 8; - r -= 8; - } - if (!(x & 0xF0000000U)) { - x <<= 4; - r -= 4; - } - if (!(x & 0xC0000000U)) { - x <<= 2; - r -= 2; - } - if (!(x & 0x80000000U)) { - x <<= 1; - r -= 1; - } - return r; -} -#endif - -unsigned int cds_lfht_fls_ulong(unsigned long x) -{ -#if (CAA_BITS_PER_LONG == 32) - return fls_u32(x); -#else - return fls_u64(x); -#endif -} - -/* - * Return the minimum order for which x <= (1UL << order). - * Return -1 if x is 0. - */ -int cds_lfht_get_count_order_u32(uint32_t x) -{ - if (!x) - return -1; - - return fls_u32(x - 1); -} - -/* - * Return the minimum order for which x <= (1UL << order). - * Return -1 if x is 0. - */ -int cds_lfht_get_count_order_ulong(unsigned long x) -{ - if (!x) - return -1; - - return cds_lfht_fls_ulong(x - 1); -} - -static -void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth); - -static -void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size, - unsigned long count); - -static long nr_cpus_mask = -1; -static long split_count_mask = -1; - -#if defined(HAVE_SYSCONF) -static void ht_init_nr_cpus_mask(void) -{ - long maxcpus; - - maxcpus = sysconf(_SC_NPROCESSORS_CONF); - if (maxcpus <= 0) { - nr_cpus_mask = -2; - return; - } - /* - * round up number of CPUs to next power of two, so we - * can use & for modulo. - */ - maxcpus = 1UL << cds_lfht_get_count_order_ulong(maxcpus); - nr_cpus_mask = maxcpus - 1; -} -#else /* #if defined(HAVE_SYSCONF) */ -static void ht_init_nr_cpus_mask(void) -{ - nr_cpus_mask = -2; -} -#endif /* #else #if defined(HAVE_SYSCONF) */ - -static -void alloc_split_items_count(struct cds_lfht *ht) -{ - struct ht_items_count *count; - - if (nr_cpus_mask == -1) { - ht_init_nr_cpus_mask(); - if (nr_cpus_mask < 0) - split_count_mask = DEFAULT_SPLIT_COUNT_MASK; - else - split_count_mask = nr_cpus_mask; - } - - assert(split_count_mask >= 0); - - if (ht->flags & CDS_LFHT_ACCOUNTING) { - ht->split_count = calloc(split_count_mask + 1, sizeof(*count)); - assert(ht->split_count); - } else { - ht->split_count = NULL; - } -} - -static -void free_split_items_count(struct cds_lfht *ht) -{ - poison_free(ht->split_count); -} - -#if defined(HAVE_SCHED_GETCPU) -static -int ht_get_split_count_index(unsigned long hash) -{ - int cpu; - - assert(split_count_mask >= 0); - cpu = sched_getcpu(); - if (caa_unlikely(cpu < 0)) - return hash & split_count_mask; - else - return cpu & split_count_mask; -} -#else /* #if defined(HAVE_SCHED_GETCPU) */ -static -int ht_get_split_count_index(unsigned long hash) -{ - return hash & split_count_mask; -} -#endif /* #else #if defined(HAVE_SCHED_GETCPU) */ - -static -void ht_count_add(struct cds_lfht *ht, unsigned long size, unsigned long hash) -{ - unsigned long split_count; - int index; - long count; - - if (caa_unlikely(!ht->split_count)) - return; - index = ht_get_split_count_index(hash); - split_count = uatomic_add_return(&ht->split_count[index].add, 1); - if (caa_likely(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1))) - return; - /* Only if number of add multiple of 1UL << COUNT_COMMIT_ORDER */ - - dbg_printf("add split count %lu\n", split_count); - count = uatomic_add_return(&ht->count, - 1UL << COUNT_COMMIT_ORDER); - if (caa_likely(count & (count - 1))) - return; - /* Only if global count is power of 2 */ - - if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) < size) - return; - dbg_printf("add set global %ld\n", count); - cds_lfht_resize_lazy_count(ht, size, - count >> (CHAIN_LEN_TARGET - 1)); -} - -static -void ht_count_del(struct cds_lfht *ht, unsigned long size, unsigned long hash) -{ - unsigned long split_count; - int index; - long count; - - if (caa_unlikely(!ht->split_count)) - return; - index = ht_get_split_count_index(hash); - split_count = uatomic_add_return(&ht->split_count[index].del, 1); - if (caa_likely(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1))) - return; - /* Only if number of deletes multiple of 1UL << COUNT_COMMIT_ORDER */ - - dbg_printf("del split count %lu\n", split_count); - count = uatomic_add_return(&ht->count, - -(1UL << COUNT_COMMIT_ORDER)); - if (caa_likely(count & (count - 1))) - return; - /* Only if global count is power of 2 */ - - if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) >= size) - return; - dbg_printf("del set global %ld\n", count); - /* - * Don't shrink table if the number of nodes is below a - * certain threshold. - */ - if (count < (1UL << COUNT_COMMIT_ORDER) * (split_count_mask + 1)) - return; - cds_lfht_resize_lazy_count(ht, size, - count >> (CHAIN_LEN_TARGET - 1)); -} - -static -void check_resize(struct cds_lfht *ht, unsigned long size, uint32_t chain_len) -{ - unsigned long count; - - if (!(ht->flags & CDS_LFHT_AUTO_RESIZE)) - return; - count = uatomic_read(&ht->count); - /* - * Use bucket-local length for small table expand and for - * environments lacking per-cpu data support. - */ - if (count >= (1UL << COUNT_COMMIT_ORDER)) - return; - if (chain_len > 100) - dbg_printf("WARNING: large chain length: %u.\n", - chain_len); - if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD) - cds_lfht_resize_lazy_grow(ht, size, - cds_lfht_get_count_order_u32(chain_len - (CHAIN_LEN_TARGET - 1))); -} - -static -struct cds_lfht_node *clear_flag(struct cds_lfht_node *node) -{ - return (struct cds_lfht_node *) (((unsigned long) node) & ~FLAGS_MASK); -} - -static -int is_removed(struct cds_lfht_node *node) -{ - return ((unsigned long) node) & REMOVED_FLAG; -} - -static -struct cds_lfht_node *flag_removed(struct cds_lfht_node *node) -{ - return (struct cds_lfht_node *) (((unsigned long) node) | REMOVED_FLAG); -} - -static -int is_bucket(struct cds_lfht_node *node) -{ - return ((unsigned long) node) & BUCKET_FLAG; -} - -static -struct cds_lfht_node *flag_bucket(struct cds_lfht_node *node) -{ - return (struct cds_lfht_node *) (((unsigned long) node) | BUCKET_FLAG); -} - -static -int is_removal_owner(struct cds_lfht_node *node) -{ - return ((unsigned long) node) & REMOVAL_OWNER_FLAG; -} - -static -struct cds_lfht_node *flag_removal_owner(struct cds_lfht_node *node) -{ - return (struct cds_lfht_node *) (((unsigned long) node) | REMOVAL_OWNER_FLAG); -} - -static -struct cds_lfht_node *get_end(void) -{ - return (struct cds_lfht_node *) END_VALUE; -} - -static -int is_end(struct cds_lfht_node *node) -{ - return clear_flag(node) == (struct cds_lfht_node *) END_VALUE; -} - -static -unsigned long _uatomic_xchg_monotonic_increase(unsigned long *ptr, - unsigned long v) -{ - unsigned long old1, old2; - - old1 = uatomic_read(ptr); - do { - old2 = old1; - if (old2 >= v) - return old2; - } while ((old1 = uatomic_cmpxchg(ptr, old2, v)) != old2); - return old2; -} - -static -void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order) -{ - return ht->mm->alloc_bucket_table(ht, order); -} - -/* - * cds_lfht_free_bucket_table() should be called with decreasing order. - * When cds_lfht_free_bucket_table(0) is called, it means the whole - * lfht is destroyed. - */ -static -void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order) -{ - return ht->mm->free_bucket_table(ht, order); -} - -static inline -struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index) -{ - return ht->bucket_at(ht, index); -} - -static inline -struct cds_lfht_node *lookup_bucket(struct cds_lfht *ht, unsigned long size, - unsigned long hash) -{ - assert(size > 0); - return bucket_at(ht, hash & (size - 1)); -} - -/* - * Remove all logically deleted nodes from a bucket up to a certain node key. - */ -static -void _cds_lfht_gc_bucket(struct cds_lfht_node *bucket, struct cds_lfht_node *node) -{ - struct cds_lfht_node *iter_prev, *iter, *next, *new_next; - - assert(!is_bucket(bucket)); - assert(!is_removed(bucket)); - assert(!is_bucket(node)); - assert(!is_removed(node)); - for (;;) { - iter_prev = bucket; - /* We can always skip the bucket node initially */ - iter = rcu_dereference(iter_prev->next); - assert(!is_removed(iter)); - assert(iter_prev->reverse_hash <= node->reverse_hash); - /* - * We should never be called with bucket (start of chain) - * and logically removed node (end of path compression - * marker) being the actual same node. This would be a - * bug in the algorithm implementation. - */ - assert(bucket != node); - for (;;) { - if (caa_unlikely(is_end(iter))) - return; - if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash)) - return; - next = rcu_dereference(clear_flag(iter)->next); - if (caa_likely(is_removed(next))) - break; - iter_prev = clear_flag(iter); - iter = next; - } - assert(!is_removed(iter)); - if (is_bucket(iter)) - new_next = flag_bucket(clear_flag(next)); - else - new_next = clear_flag(next); - (void) uatomic_cmpxchg(&iter_prev->next, iter, new_next); - } -} - -static -int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size, - struct cds_lfht_node *old_node, - struct cds_lfht_node *old_next, - struct cds_lfht_node *new_node) -{ - struct cds_lfht_node *bucket, *ret_next; - - if (!old_node) /* Return -ENOENT if asked to replace NULL node */ - return -ENOENT; - - assert(!is_removed(old_node)); - assert(!is_bucket(old_node)); - assert(!is_removed(new_node)); - assert(!is_bucket(new_node)); - assert(new_node != old_node); - for (;;) { - /* Insert after node to be replaced */ - if (is_removed(old_next)) { - /* - * Too late, the old node has been removed under us - * between lookup and replace. Fail. - */ - return -ENOENT; - } - assert(old_next == clear_flag(old_next)); - assert(new_node != old_next); - new_node->next = old_next; - /* - * Here is the whole trick for lock-free replace: we add - * the replacement node _after_ the node we want to - * replace by atomically setting its next pointer at the - * same time we set its removal flag. Given that - * the lookups/get next use an iterator aware of the - * next pointer, they will either skip the old node due - * to the removal flag and see the new node, or use - * the old node, but will not see the new one. - * This is a replacement of a node with another node - * that has the same value: we are therefore not - * removing a value from the hash table. - */ - ret_next = uatomic_cmpxchg(&old_node->next, - old_next, flag_removed(new_node)); - if (ret_next == old_next) - break; /* We performed the replacement. */ - old_next = ret_next; - } - - /* - * Ensure that the old node is not visible to readers anymore: - * lookup for the node, and remove it (along with any other - * logically removed node) if found. - */ - bucket = lookup_bucket(ht, size, bit_reverse_ulong(old_node->reverse_hash)); - _cds_lfht_gc_bucket(bucket, new_node); - - assert(is_removed(rcu_dereference(old_node->next))); - return 0; -} - -/* - * A non-NULL unique_ret pointer uses the "add unique" (or uniquify) add - * mode. A NULL unique_ret allows creation of duplicate keys. - */ -static -void _cds_lfht_add(struct cds_lfht *ht, - unsigned long hash, - cds_lfht_match_fct match, - const void *key, - unsigned long size, - struct cds_lfht_node *node, - struct cds_lfht_iter *unique_ret, - int bucket_flag) -{ - struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next, - *return_node; - struct cds_lfht_node *bucket; - - assert(!is_bucket(node)); - assert(!is_removed(node)); - bucket = lookup_bucket(ht, size, hash); - for (;;) { - uint32_t chain_len = 0; - - /* - * iter_prev points to the non-removed node prior to the - * insert location. - */ - iter_prev = bucket; - /* We can always skip the bucket node initially */ - iter = rcu_dereference(iter_prev->next); - assert(iter_prev->reverse_hash <= node->reverse_hash); - for (;;) { - if (caa_unlikely(is_end(iter))) - goto insert; - if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash)) - goto insert; - - /* bucket node is the first node of the identical-hash-value chain */ - if (bucket_flag && clear_flag(iter)->reverse_hash == node->reverse_hash) - goto insert; - - next = rcu_dereference(clear_flag(iter)->next); - if (caa_unlikely(is_removed(next))) - goto gc_node; - - /* uniquely add */ - if (unique_ret - && !is_bucket(next) - && clear_flag(iter)->reverse_hash == node->reverse_hash) { - struct cds_lfht_iter d_iter = { .node = node, .next = iter, }; - - /* - * uniquely adding inserts the node as the first - * node of the identical-hash-value node chain. - * - * This semantic ensures no duplicated keys - * should ever be observable in the table - * (including observe one node by one node - * by forward iterations) - */ - cds_lfht_next_duplicate(ht, match, key, &d_iter); - if (!d_iter.node) - goto insert; - - *unique_ret = d_iter; - return; - } - - /* Only account for identical reverse hash once */ - if (iter_prev->reverse_hash != clear_flag(iter)->reverse_hash - && !is_bucket(next)) - check_resize(ht, size, ++chain_len); - iter_prev = clear_flag(iter); - iter = next; - } - - insert: - assert(node != clear_flag(iter)); - assert(!is_removed(iter_prev)); - assert(!is_removed(iter)); - assert(iter_prev != node); - if (!bucket_flag) - node->next = clear_flag(iter); - else - node->next = flag_bucket(clear_flag(iter)); - if (is_bucket(iter)) - new_node = flag_bucket(node); - else - new_node = node; - if (uatomic_cmpxchg(&iter_prev->next, iter, - new_node) != iter) { - continue; /* retry */ - } else { - return_node = node; - goto end; - } - - gc_node: - assert(!is_removed(iter)); - if (is_bucket(iter)) - new_next = flag_bucket(clear_flag(next)); - else - new_next = clear_flag(next); - (void) uatomic_cmpxchg(&iter_prev->next, iter, new_next); - /* retry */ - } -end: - if (unique_ret) { - unique_ret->node = return_node; - /* unique_ret->next left unset, never used. */ - } -} - -static -int _cds_lfht_del(struct cds_lfht *ht, unsigned long size, - struct cds_lfht_node *node) -{ - struct cds_lfht_node *bucket, *next; - - if (!node) /* Return -ENOENT if asked to delete NULL node */ - return -ENOENT; - - /* logically delete the node */ - assert(!is_bucket(node)); - assert(!is_removed(node)); - assert(!is_removal_owner(node)); - - /* - * We are first checking if the node had previously been - * logically removed (this check is not atomic with setting the - * logical removal flag). Return -ENOENT if the node had - * previously been removed. - */ - next = rcu_dereference(node->next); - if (caa_unlikely(is_removed(next))) - return -ENOENT; - assert(!is_bucket(next)); - /* - * We set the REMOVED_FLAG unconditionally. Note that there may - * be more than one concurrent thread setting this flag. - * Knowing which wins the race will be known after the garbage - * collection phase, stay tuned! - */ - uatomic_or(&node->next, REMOVED_FLAG); - /* We performed the (logical) deletion. */ - - /* - * Ensure that the node is not visible to readers anymore: lookup for - * the node, and remove it (along with any other logically removed node) - * if found. - */ - bucket = lookup_bucket(ht, size, bit_reverse_ulong(node->reverse_hash)); - _cds_lfht_gc_bucket(bucket, node); - - assert(is_removed(rcu_dereference(node->next))); - /* - * Last phase: atomically exchange node->next with a version - * having "REMOVAL_OWNER_FLAG" set. If the returned node->next - * pointer did _not_ have "REMOVAL_OWNER_FLAG" set, we now own - * the node and win the removal race. - * It is interesting to note that all "add" paths are forbidden - * to change the next pointer starting from the point where the - * REMOVED_FLAG is set, so here using a read, followed by a - * xchg() suffice to guarantee that the xchg() will ever only - * set the "REMOVAL_OWNER_FLAG" (or change nothing if the flag - * was already set). - */ - if (!is_removal_owner(uatomic_xchg(&node->next, - flag_removal_owner(node->next)))) - return 0; - else - return -ENOENT; -} - -static -void *partition_resize_thread(void *arg) -{ - struct partition_resize_work *work = arg; - - work->ht->flavor->register_thread(); - work->fct(work->ht, work->i, work->start, work->len); - work->ht->flavor->unregister_thread(); - return NULL; -} - -static -void partition_resize_helper(struct cds_lfht *ht, unsigned long i, - unsigned long len, - void (*fct)(struct cds_lfht *ht, unsigned long i, - unsigned long start, unsigned long len)) -{ - unsigned long partition_len; - struct partition_resize_work *work; - int thread, ret; - unsigned long nr_threads; - - /* - * Note: nr_cpus_mask + 1 is always power of 2. - * We spawn just the number of threads we need to satisfy the minimum - * partition size, up to the number of CPUs in the system. - */ - if (nr_cpus_mask > 0) { - nr_threads = min(nr_cpus_mask + 1, - len >> MIN_PARTITION_PER_THREAD_ORDER); - } else { - nr_threads = 1; - } - partition_len = len >> cds_lfht_get_count_order_ulong(nr_threads); - work = calloc(nr_threads, sizeof(*work)); - assert(work); - for (thread = 0; thread < nr_threads; thread++) { - work[thread].ht = ht; - work[thread].i = i; - work[thread].len = partition_len; - work[thread].start = thread * partition_len; - work[thread].fct = fct; - ret = pthread_create(&(work[thread].thread_id), ht->resize_attr, - partition_resize_thread, &work[thread]); - assert(!ret); - } - for (thread = 0; thread < nr_threads; thread++) { - ret = pthread_join(work[thread].thread_id, NULL); - assert(!ret); - } - free(work); -} - -/* - * Holding RCU read lock to protect _cds_lfht_add against memory - * reclaim that could be performed by other call_rcu worker threads (ABA - * problem). - * - * When we reach a certain length, we can split this population phase over - * many worker threads, based on the number of CPUs available in the system. - * This should therefore take care of not having the expand lagging behind too - * many concurrent insertion threads by using the scheduler's ability to - * schedule bucket node population fairly with insertions. - */ -static -void init_table_populate_partition(struct cds_lfht *ht, unsigned long i, - unsigned long start, unsigned long len) -{ - unsigned long j, size = 1UL << (i - 1); - - assert(i > MIN_TABLE_ORDER); - ht->flavor->read_lock(); - for (j = size + start; j < size + start + len; j++) { - struct cds_lfht_node *new_node = bucket_at(ht, j); - - assert(j >= size && j < (size << 1)); - dbg_printf("init populate: order %lu index %lu hash %lu\n", - i, j, j); - new_node->reverse_hash = bit_reverse_ulong(j); - _cds_lfht_add(ht, j, NULL, NULL, size, new_node, NULL, 1); - } - ht->flavor->read_unlock(); -} - -static -void init_table_populate(struct cds_lfht *ht, unsigned long i, - unsigned long len) -{ - assert(nr_cpus_mask != -1); - if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) { - ht->flavor->thread_online(); - init_table_populate_partition(ht, i, 0, len); - ht->flavor->thread_offline(); - return; - } - partition_resize_helper(ht, i, len, init_table_populate_partition); -} - -static -void init_table(struct cds_lfht *ht, - unsigned long first_order, unsigned long last_order) -{ - unsigned long i; - - dbg_printf("init table: first_order %lu last_order %lu\n", - first_order, last_order); - assert(first_order > MIN_TABLE_ORDER); - for (i = first_order; i <= last_order; i++) { - unsigned long len; - - len = 1UL << (i - 1); - dbg_printf("init order %lu len: %lu\n", i, len); - - /* Stop expand if the resize target changes under us */ - if (CMM_LOAD_SHARED(ht->resize_target) < (1UL << i)) - break; - - cds_lfht_alloc_bucket_table(ht, i); - - /* - * Set all bucket nodes reverse hash values for a level and - * link all bucket nodes into the table. - */ - init_table_populate(ht, i, len); - - /* - * Update table size. - */ - cmm_smp_wmb(); /* populate data before RCU size */ - CMM_STORE_SHARED(ht->size, 1UL << i); - - dbg_printf("init new size: %lu\n", 1UL << i); - if (CMM_LOAD_SHARED(ht->in_progress_destroy)) - break; - } -} - -/* - * Holding RCU read lock to protect _cds_lfht_remove against memory - * reclaim that could be performed by other call_rcu worker threads (ABA - * problem). - * For a single level, we logically remove and garbage collect each node. - * - * As a design choice, we perform logical removal and garbage collection on a - * node-per-node basis to simplify this algorithm. We also assume keeping good - * cache locality of the operation would overweight possible performance gain - * that could be achieved by batching garbage collection for multiple levels. - * However, this would have to be justified by benchmarks. - * - * Concurrent removal and add operations are helping us perform garbage - * collection of logically removed nodes. We guarantee that all logically - * removed nodes have been garbage-collected (unlinked) before call_rcu is - * invoked to free a hole level of bucket nodes (after a grace period). - * - * Logical removal and garbage collection can therefore be done in batch or on a - * node-per-node basis, as long as the guarantee above holds. - * - * When we reach a certain length, we can split this removal over many worker - * threads, based on the number of CPUs available in the system. This should - * take care of not letting resize process lag behind too many concurrent - * updater threads actively inserting into the hash table. - */ -static -void remove_table_partition(struct cds_lfht *ht, unsigned long i, - unsigned long start, unsigned long len) -{ - unsigned long j, size = 1UL << (i - 1); - - assert(i > MIN_TABLE_ORDER); - ht->flavor->read_lock(); - for (j = size + start; j < size + start + len; j++) { - struct cds_lfht_node *fini_bucket = bucket_at(ht, j); - struct cds_lfht_node *parent_bucket = bucket_at(ht, j - size); - - assert(j >= size && j < (size << 1)); - dbg_printf("remove entry: order %lu index %lu hash %lu\n", - i, j, j); - /* Set the REMOVED_FLAG to freeze the ->next for gc */ - uatomic_or(&fini_bucket->next, REMOVED_FLAG); - _cds_lfht_gc_bucket(parent_bucket, fini_bucket); - } - ht->flavor->read_unlock(); -} - -static -void remove_table(struct cds_lfht *ht, unsigned long i, unsigned long len) -{ - - assert(nr_cpus_mask != -1); - if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) { - ht->flavor->thread_online(); - remove_table_partition(ht, i, 0, len); - ht->flavor->thread_offline(); - return; - } - partition_resize_helper(ht, i, len, remove_table_partition); -} - -/* - * fini_table() is never called for first_order == 0, which is why - * free_by_rcu_order == 0 can be used as criterion to know if free must - * be called. - */ -static -void fini_table(struct cds_lfht *ht, - unsigned long first_order, unsigned long last_order) -{ - long i; - unsigned long free_by_rcu_order = 0; - - dbg_printf("fini table: first_order %lu last_order %lu\n", - first_order, last_order); - assert(first_order > MIN_TABLE_ORDER); - for (i = last_order; i >= first_order; i--) { - unsigned long len; - - len = 1UL << (i - 1); - dbg_printf("fini order %lu len: %lu\n", i, len); - - /* Stop shrink if the resize target changes under us */ - if (CMM_LOAD_SHARED(ht->resize_target) > (1UL << (i - 1))) - break; - - cmm_smp_wmb(); /* populate data before RCU size */ - CMM_STORE_SHARED(ht->size, 1UL << (i - 1)); - - /* - * We need to wait for all add operations to reach Q.S. (and - * thus use the new table for lookups) before we can start - * releasing the old bucket nodes. Otherwise their lookup will - * return a logically removed node as insert position. - */ - ht->flavor->update_synchronize_rcu(); - if (free_by_rcu_order) - cds_lfht_free_bucket_table(ht, free_by_rcu_order); - - /* - * Set "removed" flag in bucket nodes about to be removed. - * Unlink all now-logically-removed bucket node pointers. - * Concurrent add/remove operation are helping us doing - * the gc. - */ - remove_table(ht, i, len); - - free_by_rcu_order = i; - - dbg_printf("fini new size: %lu\n", 1UL << i); - if (CMM_LOAD_SHARED(ht->in_progress_destroy)) - break; - } - - if (free_by_rcu_order) { - ht->flavor->update_synchronize_rcu(); - cds_lfht_free_bucket_table(ht, free_by_rcu_order); - } -} - -static -void cds_lfht_create_bucket(struct cds_lfht *ht, unsigned long size) -{ - struct cds_lfht_node *prev, *node; - unsigned long order, len, i; - - cds_lfht_alloc_bucket_table(ht, 0); - - dbg_printf("create bucket: order 0 index 0 hash 0\n"); - node = bucket_at(ht, 0); - node->next = flag_bucket(get_end()); - node->reverse_hash = 0; - - for (order = 1; order < cds_lfht_get_count_order_ulong(size) + 1; order++) { - len = 1UL << (order - 1); - cds_lfht_alloc_bucket_table(ht, order); - - for (i = 0; i < len; i++) { - /* - * Now, we are trying to init the node with the - * hash=(len+i) (which is also a bucket with the - * index=(len+i)) and insert it into the hash table, - * so this node has to be inserted after the bucket - * with the index=(len+i)&(len-1)=i. And because there - * is no other non-bucket node nor bucket node with - * larger index/hash inserted, so the bucket node - * being inserted should be inserted directly linked - * after the bucket node with index=i. - */ - prev = bucket_at(ht, i); - node = bucket_at(ht, len + i); - - dbg_printf("create bucket: order %lu index %lu hash %lu\n", - order, len + i, len + i); - node->reverse_hash = bit_reverse_ulong(len + i); - - /* insert after prev */ - assert(is_bucket(prev->next)); - node->next = prev->next; - prev->next = flag_bucket(node); - } - } -} - -struct cds_lfht *_cds_lfht_new(unsigned long init_size, - unsigned long min_nr_alloc_buckets, - unsigned long max_nr_buckets, - int flags, - const struct cds_lfht_mm_type *mm, - const struct rcu_flavor_struct *flavor, - pthread_attr_t *attr) -{ - struct cds_lfht *ht; - unsigned long order; - - /* min_nr_alloc_buckets must be power of two */ - if (!min_nr_alloc_buckets || (min_nr_alloc_buckets & (min_nr_alloc_buckets - 1))) - return NULL; - - /* init_size must be power of two */ - if (!init_size || (init_size & (init_size - 1))) - return NULL; - - /* - * Memory management plugin default. - */ - if (!mm) { - if (CAA_BITS_PER_LONG > 32 - && max_nr_buckets - && max_nr_buckets <= (1ULL << 32)) { - /* - * For 64-bit architectures, with max number of - * buckets small enough not to use the entire - * 64-bit memory mapping space (and allowing a - * fair number of hash table instances), use the - * mmap allocator, which is faster than the - * order allocator. - */ - mm = &cds_lfht_mm_mmap; - } else { - /* - * The fallback is to use the order allocator. - */ - mm = &cds_lfht_mm_order; - } - } - - /* max_nr_buckets == 0 for order based mm means infinite */ - if (mm == &cds_lfht_mm_order && !max_nr_buckets) - max_nr_buckets = 1UL << (MAX_TABLE_ORDER - 1); - - /* max_nr_buckets must be power of two */ - if (!max_nr_buckets || (max_nr_buckets & (max_nr_buckets - 1))) - return NULL; - - min_nr_alloc_buckets = max(min_nr_alloc_buckets, MIN_TABLE_SIZE); - init_size = max(init_size, MIN_TABLE_SIZE); - max_nr_buckets = max(max_nr_buckets, min_nr_alloc_buckets); - init_size = min(init_size, max_nr_buckets); - - ht = mm->alloc_cds_lfht(min_nr_alloc_buckets, max_nr_buckets); - assert(ht); - assert(ht->mm == mm); - assert(ht->bucket_at == mm->bucket_at); - - ht->flags = flags; - ht->flavor = flavor; - ht->resize_attr = attr; - alloc_split_items_count(ht); - /* this mutex should not nest in read-side C.S. */ - pthread_mutex_init(&ht->resize_mutex, NULL); - order = cds_lfht_get_count_order_ulong(init_size); - ht->resize_target = 1UL << order; - cds_lfht_create_bucket(ht, 1UL << order); - ht->size = 1UL << order; - return ht; -} - -void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash, - cds_lfht_match_fct match, const void *key, - struct cds_lfht_iter *iter) -{ - struct cds_lfht_node *node, *next, *bucket; - unsigned long reverse_hash, size; - - reverse_hash = bit_reverse_ulong(hash); - - size = rcu_dereference(ht->size); - bucket = lookup_bucket(ht, size, hash); - /* We can always skip the bucket node initially */ - node = rcu_dereference(bucket->next); - node = clear_flag(node); - for (;;) { - if (caa_unlikely(is_end(node))) { - node = next = NULL; - break; - } - if (caa_unlikely(node->reverse_hash > reverse_hash)) { - node = next = NULL; - break; - } - next = rcu_dereference(node->next); - assert(node == clear_flag(node)); - if (caa_likely(!is_removed(next)) - && !is_bucket(next) - && node->reverse_hash == reverse_hash - && caa_likely(match(node, key))) { - break; - } - node = clear_flag(next); - } - assert(!node || !is_bucket(rcu_dereference(node->next))); - iter->node = node; - iter->next = next; -} - -void cds_lfht_next_duplicate(struct cds_lfht *ht, cds_lfht_match_fct match, - const void *key, struct cds_lfht_iter *iter) -{ - struct cds_lfht_node *node, *next; - unsigned long reverse_hash; - - node = iter->node; - reverse_hash = node->reverse_hash; - next = iter->next; - node = clear_flag(next); - - for (;;) { - if (caa_unlikely(is_end(node))) { - node = next = NULL; - break; - } - if (caa_unlikely(node->reverse_hash > reverse_hash)) { - node = next = NULL; - break; - } - next = rcu_dereference(node->next); - if (caa_likely(!is_removed(next)) - && !is_bucket(next) - && caa_likely(match(node, key))) { - break; - } - node = clear_flag(next); - } - assert(!node || !is_bucket(rcu_dereference(node->next))); - iter->node = node; - iter->next = next; -} - -void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter) -{ - struct cds_lfht_node *node, *next; - - node = clear_flag(iter->next); - for (;;) { - if (caa_unlikely(is_end(node))) { - node = next = NULL; - break; - } - next = rcu_dereference(node->next); - if (caa_likely(!is_removed(next)) - && !is_bucket(next)) { - break; - } - node = clear_flag(next); - } - assert(!node || !is_bucket(rcu_dereference(node->next))); - iter->node = node; - iter->next = next; -} - -void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter) -{ - /* - * Get next after first bucket node. The first bucket node is the - * first node of the linked list. - */ - iter->next = bucket_at(ht, 0)->next; - cds_lfht_next(ht, iter); -} - -void cds_lfht_add(struct cds_lfht *ht, unsigned long hash, - struct cds_lfht_node *node) -{ - unsigned long size; - - node->reverse_hash = bit_reverse_ulong(hash); - size = rcu_dereference(ht->size); - _cds_lfht_add(ht, hash, NULL, NULL, size, node, NULL, 0); - ht_count_add(ht, size, hash); -} - -struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, - unsigned long hash, - cds_lfht_match_fct match, - const void *key, - struct cds_lfht_node *node) -{ - unsigned long size; - struct cds_lfht_iter iter; - - node->reverse_hash = bit_reverse_ulong(hash); - size = rcu_dereference(ht->size); - _cds_lfht_add(ht, hash, match, key, size, node, &iter, 0); - if (iter.node == node) - ht_count_add(ht, size, hash); - return iter.node; -} - -struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht, - unsigned long hash, - cds_lfht_match_fct match, - const void *key, - struct cds_lfht_node *node) -{ - unsigned long size; - struct cds_lfht_iter iter; - - node->reverse_hash = bit_reverse_ulong(hash); - size = rcu_dereference(ht->size); - for (;;) { - _cds_lfht_add(ht, hash, match, key, size, node, &iter, 0); - if (iter.node == node) { - ht_count_add(ht, size, hash); - return NULL; - } - - if (!_cds_lfht_replace(ht, size, iter.node, iter.next, node)) - return iter.node; - } -} - -int cds_lfht_replace(struct cds_lfht *ht, - struct cds_lfht_iter *old_iter, - unsigned long hash, - cds_lfht_match_fct match, - const void *key, - struct cds_lfht_node *new_node) -{ - unsigned long size; - - new_node->reverse_hash = bit_reverse_ulong(hash); - if (!old_iter->node) - return -ENOENT; - if (caa_unlikely(old_iter->node->reverse_hash != new_node->reverse_hash)) - return -EINVAL; - if (caa_unlikely(!match(old_iter->node, key))) - return -EINVAL; - size = rcu_dereference(ht->size); - return _cds_lfht_replace(ht, size, old_iter->node, old_iter->next, - new_node); -} - -int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node) -{ - unsigned long size, hash; - int ret; - - size = rcu_dereference(ht->size); - ret = _cds_lfht_del(ht, size, node); - if (!ret) { - hash = bit_reverse_ulong(node->reverse_hash); - ht_count_del(ht, size, hash); - } - return ret; -} - -static -int cds_lfht_delete_bucket(struct cds_lfht *ht) -{ - struct cds_lfht_node *node; - unsigned long order, i, size; - - /* Check that the table is empty */ - node = bucket_at(ht, 0); - do { - node = clear_flag(node)->next; - if (!is_bucket(node)) - return -EPERM; - assert(!is_removed(node)); - } while (!is_end(node)); - /* - * size accessed without rcu_dereference because hash table is - * being destroyed. - */ - size = ht->size; - /* Internal sanity check: all nodes left should be bucket */ - for (i = 0; i < size; i++) { - node = bucket_at(ht, i); - dbg_printf("delete bucket: index %lu expected hash %lu hash %lu\n", - i, i, bit_reverse_ulong(node->reverse_hash)); - assert(is_bucket(node->next)); - } - - for (order = cds_lfht_get_count_order_ulong(size); (long)order >= 0; order--) - cds_lfht_free_bucket_table(ht, order); - - return 0; -} - -/* - * Should only be called when no more concurrent readers nor writers can - * possibly access the table. - */ -int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr) -{ - int ret; - - /* Wait for in-flight resize operations to complete */ - _CMM_STORE_SHARED(ht->in_progress_destroy, 1); - cmm_smp_mb(); /* Store destroy before load resize */ - while (uatomic_read(&ht->in_progress_resize)) - poll(NULL, 0, 100); /* wait for 100ms */ - ret = cds_lfht_delete_bucket(ht); - if (ret) - return ret; - free_split_items_count(ht); - if (attr) - *attr = ht->resize_attr; - poison_free(ht); - return ret; -} - -void cds_lfht_count_nodes(struct cds_lfht *ht, - long *approx_before, - unsigned long *count, - long *approx_after) -{ - struct cds_lfht_node *node, *next; - unsigned long nr_bucket = 0, nr_removed = 0; - - *approx_before = 0; - if (ht->split_count) { - int i; - - for (i = 0; i < split_count_mask + 1; i++) { - *approx_before += uatomic_read(&ht->split_count[i].add); - *approx_before -= uatomic_read(&ht->split_count[i].del); - } - } - - *count = 0; - - /* Count non-bucket nodes in the table */ - node = bucket_at(ht, 0); - do { - next = rcu_dereference(node->next); - if (is_removed(next)) { - if (!is_bucket(next)) - (nr_removed)++; - else - (nr_bucket)++; - } else if (!is_bucket(next)) - (*count)++; - else - (nr_bucket)++; - node = clear_flag(next); - } while (!is_end(node)); - dbg_printf("number of logically removed nodes: %lu\n", nr_removed); - dbg_printf("number of bucket nodes: %lu\n", nr_bucket); - *approx_after = 0; - if (ht->split_count) { - int i; - - for (i = 0; i < split_count_mask + 1; i++) { - *approx_after += uatomic_read(&ht->split_count[i].add); - *approx_after -= uatomic_read(&ht->split_count[i].del); - } - } -} - -/* called with resize mutex held */ -static -void _do_cds_lfht_grow(struct cds_lfht *ht, - unsigned long old_size, unsigned long new_size) -{ - unsigned long old_order, new_order; - - old_order = cds_lfht_get_count_order_ulong(old_size); - new_order = cds_lfht_get_count_order_ulong(new_size); - dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", - old_size, old_order, new_size, new_order); - assert(new_size > old_size); - init_table(ht, old_order + 1, new_order); -} - -/* called with resize mutex held */ -static -void _do_cds_lfht_shrink(struct cds_lfht *ht, - unsigned long old_size, unsigned long new_size) -{ - unsigned long old_order, new_order; - - new_size = max(new_size, MIN_TABLE_SIZE); - old_order = cds_lfht_get_count_order_ulong(old_size); - new_order = cds_lfht_get_count_order_ulong(new_size); - dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", - old_size, old_order, new_size, new_order); - assert(new_size < old_size); - - /* Remove and unlink all bucket nodes to remove. */ - fini_table(ht, new_order + 1, old_order); -} - - -/* called with resize mutex held */ -static -void _do_cds_lfht_resize(struct cds_lfht *ht) -{ - unsigned long new_size, old_size; - - /* - * Resize table, re-do if the target size has changed under us. - */ - do { - assert(uatomic_read(&ht->in_progress_resize)); - if (CMM_LOAD_SHARED(ht->in_progress_destroy)) - break; - ht->resize_initiated = 1; - old_size = ht->size; - new_size = CMM_LOAD_SHARED(ht->resize_target); - if (old_size < new_size) - _do_cds_lfht_grow(ht, old_size, new_size); - else if (old_size > new_size) - _do_cds_lfht_shrink(ht, old_size, new_size); - ht->resize_initiated = 0; - /* write resize_initiated before read resize_target */ - cmm_smp_mb(); - } while (ht->size != CMM_LOAD_SHARED(ht->resize_target)); -} - -static -unsigned long resize_target_grow(struct cds_lfht *ht, unsigned long new_size) -{ - return _uatomic_xchg_monotonic_increase(&ht->resize_target, new_size); -} - -static -void resize_target_update_count(struct cds_lfht *ht, - unsigned long count) -{ - count = max(count, MIN_TABLE_SIZE); - count = min(count, ht->max_nr_buckets); - uatomic_set(&ht->resize_target, count); -} - -void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size) -{ - resize_target_update_count(ht, new_size); - CMM_STORE_SHARED(ht->resize_initiated, 1); - ht->flavor->thread_offline(); - pthread_mutex_lock(&ht->resize_mutex); - _do_cds_lfht_resize(ht); - pthread_mutex_unlock(&ht->resize_mutex); - ht->flavor->thread_online(); -} - -static -void do_resize_cb(struct rcu_head *head) -{ - struct rcu_resize_work *work = - caa_container_of(head, struct rcu_resize_work, head); - struct cds_lfht *ht = work->ht; - - ht->flavor->thread_offline(); - pthread_mutex_lock(&ht->resize_mutex); - _do_cds_lfht_resize(ht); - pthread_mutex_unlock(&ht->resize_mutex); - ht->flavor->thread_online(); - poison_free(work); - cmm_smp_mb(); /* finish resize before decrement */ - uatomic_dec(&ht->in_progress_resize); -} - -static -void __cds_lfht_resize_lazy_launch(struct cds_lfht *ht) -{ - struct rcu_resize_work *work; - - /* Store resize_target before read resize_initiated */ - cmm_smp_mb(); - if (!CMM_LOAD_SHARED(ht->resize_initiated)) { - uatomic_inc(&ht->in_progress_resize); - cmm_smp_mb(); /* increment resize count before load destroy */ - if (CMM_LOAD_SHARED(ht->in_progress_destroy)) { - uatomic_dec(&ht->in_progress_resize); - return; - } - work = malloc(sizeof(*work)); - work->ht = ht; - ht->flavor->update_call_rcu(&work->head, do_resize_cb); - CMM_STORE_SHARED(ht->resize_initiated, 1); - } -} - -static -void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth) -{ - unsigned long target_size = size << growth; - - target_size = min(target_size, ht->max_nr_buckets); - if (resize_target_grow(ht, target_size) >= target_size) - return; - - __cds_lfht_resize_lazy_launch(ht); -} - -/* - * We favor grow operations over shrink. A shrink operation never occurs - * if a grow operation is queued for lazy execution. A grow operation - * cancels any pending shrink lazy execution. - */ -static -void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size, - unsigned long count) -{ - if (!(ht->flags & CDS_LFHT_AUTO_RESIZE)) - return; - count = max(count, MIN_TABLE_SIZE); - count = min(count, ht->max_nr_buckets); - if (count == size) - return; /* Already the right size, no resize needed */ - if (count > size) { /* lazy grow */ - if (resize_target_grow(ht, count) >= count) - return; - } else { /* lazy shrink */ - for (;;) { - unsigned long s; - - s = uatomic_cmpxchg(&ht->resize_target, size, count); - if (s == size) - break; /* no resize needed */ - if (s > size) - return; /* growing is/(was just) in progress */ - if (s <= count) - return; /* some other thread do shrink */ - size = s; - } - } - __cds_lfht_resize_lazy_launch(ht); -}