From d6b189345152f407360bc287997d38d30054bd2c Mon Sep 17 00:00:00 2001 From: David Goulet Date: Wed, 2 Nov 2011 15:43:50 -0400 Subject: [PATCH] Update RCU hashtable from upstream urcu Signed-off-by: David Goulet --- hashtable/rculfhash.c | 740 ++++++++++++++++++++++++------------------ hashtable/rculfhash.h | 46 ++- 2 files changed, 457 insertions(+), 329 deletions(-) diff --git a/hashtable/rculfhash.c b/hashtable/rculfhash.c index c79bafd42..27c0eeb10 100644 --- a/hashtable/rculfhash.c +++ b/hashtable/rculfhash.c @@ -53,7 +53,7 @@ * operation. * - The resize operation for larger tables (and available through an * API) allows both expanding and shrinking the hash table. - * - Per-CPU Split-counters are used to keep track of the number of + * - 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. @@ -91,12 +91,32 @@ * the "dummy node" tables. * - There is one dummy node table per hash index order. The size of * each dummy node table is half the number of hashes contained in - * this order. - * - call_rcu is used to garbage-collect the old order table. + * this order (except for order 0). + * - synchronzie_rcu is used to garbage-collect the old dummy node table. * - The per-order dummy node tables contain a compact version of the * hash table nodes. These tables are invariant after they are * populated into the hash table. - * + * + * Dummy node tables: + * + * hash table hash table the last all dummy node tables + * order size dummy 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 dummy 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 dummy node table + * shrink hash table from order 6 to 5: fini the index=6 dummy node table + * * A bit of ascii art explanation: * * Order index is the off-by-one compare to the actual power of 2 because @@ -119,12 +139,9 @@ * * order bits reverse * 0 0 000 000 - * | - * 1 | 1 001 100 <- <- - * | | | | - * 2 | | 2 010 010 | | + * 1 | 1 001 100 <- + * 2 | | 2 010 010 <- | * | | | 3 011 110 | <- | - * | | | | | | | * 3 -> | | | 4 100 001 | | * -> | | 5 101 101 | * -> | 6 110 011 @@ -139,6 +156,7 @@ #include #include +#include "config.h" #include #include #include @@ -156,12 +174,13 @@ #endif /* - * Per-CPU split-counters lazily update the global counter each 1024 + * 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 @@ -204,15 +223,37 @@ /* Value of the end pointer. Should not interact with flags. */ #define END_VALUE NULL +/* + * 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_level: Contains the per order-index-level dummy node table. The + * size of each dummy node table is half the number of hashes contained + * in this order (except for order 0). The minimum allocation size + * parameter allows combining the dummy node arrays of the lowermost + * levels to improve cache locality for small index orders. + */ struct rcu_level { - struct rcu_head head; + /* Note: manually update allocation length when adding a field */ struct _cds_lfht_node nodes[0]; }; +/* + * rcu_table: Contains the size and desired new size if a resize + * operation is in progress, as well as the statically-sized array of + * rcu_level pointers. + */ struct rcu_table { unsigned long size; /* always a power of 2, shared (RCU) */ unsigned long resize_target; @@ -220,10 +261,17 @@ struct rcu_table { struct rcu_level *tbl[MAX_TABLE_ORDER]; }; +/* + * cds_lfht: Top-level data structure representing a lock-free hash + * table. Defined in the implementation file to make it be an opaque + * cookie to users. + */ struct cds_lfht { struct rcu_table t; cds_lfht_hash_fct hash_fct; cds_lfht_compare_fct compare_fct; + unsigned long min_alloc_order; + unsigned long min_alloc_size; unsigned long hash_seed; int flags; /* @@ -246,33 +294,37 @@ struct cds_lfht { void (*cds_lfht_rcu_unregister_thread)(void); pthread_attr_t *resize_attr; /* Resize threads attributes */ long count; /* global approximate item count */ - struct ht_items_count *percpu_count; /* per-cpu item count */ + struct ht_items_count *split_count; /* split item count */ }; +/* + * 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 { - struct rcu_head head; + 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); }; -enum add_mode { - ADD_DEFAULT = 0, - ADD_UNIQUE = 1, - ADD_REPLACE = 2, -}; - static -struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, - unsigned long size, - struct cds_lfht_node *node, - enum add_mode mode, int dummy); +void _cds_lfht_add(struct cds_lfht *ht, + unsigned long size, + struct cds_lfht_node *node, + struct cds_lfht_iter *unique_ret, + int dummy); /* * Algorithm to reverse bits in a word by lookup table, extended to @@ -439,38 +491,44 @@ unsigned int fls_u32(uint32_t x) unsigned int fls_ulong(unsigned long x) { -#if (CAA_BITS_PER_lONG == 32) +#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 get_count_order_u32(uint32_t x) { - int order; + if (!x) + return -1; - order = fls_u32(x) - 1; - if (x & (x - 1)) - order++; - return order; + return fls_u32(x - 1); } +/* + * Return the minimum order for which x <= (1UL << order). + * Return -1 if x is 0. + */ int get_count_order_ulong(unsigned long x) { - int order; + if (!x) + return -1; - order = fls_ulong(x) - 1; - if (x & (x - 1)) - order++; - return order; + return fls_ulong(x - 1); } #ifdef POISON_FREE -#define poison_free(ptr) \ - do { \ - memset(ptr, 0x42, sizeof(*(ptr))); \ - free(ptr); \ +#define poison_free(ptr) \ + do { \ + if (ptr) { \ + memset(ptr, 0x42, sizeof(*(ptr))); \ + free(ptr); \ + } \ } while (0) #else #define poison_free(ptr) free(ptr) @@ -479,85 +537,101 @@ int get_count_order_ulong(unsigned long x) static void cds_lfht_resize_lazy(struct cds_lfht *ht, unsigned long size, int growth); -/* - * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are - * available, then we support hash table item accounting. - * In the unfortunate event the number of CPUs reported would be - * inaccurate, we use modulo arithmetic on the number of CPUs we got. - */ -#if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) - 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 << 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 -struct ht_items_count *alloc_per_cpu_items_count(void) +void alloc_split_items_count(struct cds_lfht *ht) { struct ht_items_count *count; - switch (nr_cpus_mask) { - case -2: - return NULL; - case -1: - { - long maxcpus; - - maxcpus = sysconf(_SC_NPROCESSORS_CONF); - if (maxcpus <= 0) { - nr_cpus_mask = -2; - return NULL; - } - /* - * round up number of CPUs to next power of two, so we - * can use & for modulo. - */ - maxcpus = 1UL << get_count_order_ulong(maxcpus); - nr_cpus_mask = maxcpus - 1; + 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; } - /* Fall-through */ - default: - return calloc(nr_cpus_mask + 1, sizeof(*count)); + + 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_per_cpu_items_count(struct ht_items_count *count) +void free_split_items_count(struct cds_lfht *ht) { - poison_free(count); + poison_free(ht->split_count); } +#if defined(HAVE_SCHED_GETCPU) static -int ht_get_cpu(void) +int ht_get_split_count_index(unsigned long hash) { int cpu; - assert(nr_cpus_mask >= 0); + assert(split_count_mask >= 0); cpu = sched_getcpu(); if (unlikely(cpu < 0)) - return cpu; + return hash & split_count_mask; else - return cpu & nr_cpus_mask; + 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) +void ht_count_add(struct cds_lfht *ht, unsigned long size, unsigned long hash) { - unsigned long percpu_count; - int cpu; + unsigned long split_count; + int index; - if (unlikely(!ht->percpu_count)) - return; - cpu = ht_get_cpu(); - if (unlikely(cpu < 0)) + if (unlikely(!ht->split_count)) return; - percpu_count = uatomic_add_return(&ht->percpu_count[cpu].add, 1); - if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) { + index = ht_get_split_count_index(hash); + split_count = uatomic_add_return(&ht->split_count[index].add, 1); + if (unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) { long count; - dbg_printf("add percpu %lu\n", percpu_count); + dbg_printf("add split count %lu\n", split_count); count = uatomic_add_return(&ht->count, 1UL << COUNT_COMMIT_ORDER); /* If power of 2 */ @@ -572,21 +646,19 @@ void ht_count_add(struct cds_lfht *ht, unsigned long size) } static -void ht_count_del(struct cds_lfht *ht, unsigned long size) +void ht_count_del(struct cds_lfht *ht, unsigned long size, unsigned long hash) { - unsigned long percpu_count; - int cpu; + unsigned long split_count; + int index; - if (unlikely(!ht->percpu_count)) - return; - cpu = ht_get_cpu(); - if (unlikely(cpu < 0)) + if (unlikely(!ht->split_count)) return; - percpu_count = uatomic_add_return(&ht->percpu_count[cpu].del, 1); - if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) { + index = ht_get_split_count_index(hash); + split_count = uatomic_add_return(&ht->split_count[index].del, 1); + if (unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) { long count; - dbg_printf("del percpu %lu\n", percpu_count); + dbg_printf("del split count %lu\n", split_count); count = uatomic_add_return(&ht->count, -(1UL << COUNT_COMMIT_ORDER)); /* If power of 2 */ @@ -598,7 +670,7 @@ void ht_count_del(struct cds_lfht *ht, unsigned long size) * Don't shrink table if the number of nodes is below a * certain threshold. */ - if (count < (1UL << COUNT_COMMIT_ORDER) * (nr_cpus_mask + 1)) + if (count < (1UL << COUNT_COMMIT_ORDER) * (split_count_mask + 1)) return; cds_lfht_resize_lazy_count(ht, size, count >> (CHAIN_LEN_TARGET - 1)); @@ -606,34 +678,6 @@ void ht_count_del(struct cds_lfht *ht, unsigned long size) } } -#else /* #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */ - -static const long nr_cpus_mask = -2; - -static -struct ht_items_count *alloc_per_cpu_items_count(void) -{ - return NULL; -} - -static -void free_per_cpu_items_count(struct ht_items_count *count) -{ -} - -static -void ht_count_add(struct cds_lfht *ht, unsigned long size) -{ -} - -static -void ht_count_del(struct cds_lfht *ht, unsigned long size) -{ -} - -#endif /* #else #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */ - - static void check_resize(struct cds_lfht *ht, unsigned long size, uint32_t chain_len) { @@ -713,11 +757,28 @@ unsigned long _uatomic_max(unsigned long *ptr, unsigned long v) } static -void cds_lfht_free_level(struct rcu_head *head) +struct _cds_lfht_node *lookup_bucket(struct cds_lfht *ht, unsigned long size, + unsigned long hash) { - struct rcu_level *l = - caa_container_of(head, struct rcu_level, head); - poison_free(l); + unsigned long index, order; + + assert(size > 0); + index = hash & (size - 1); + + if (index < ht->min_alloc_size) { + dbg_printf("lookup hash %lu index %lu order 0 aridx 0\n", + hash, index); + return &ht->t.tbl[0]->nodes[index]; + } + /* + * equivalent to get_count_order_ulong(index + 1), but optimizes + * away the non-existing 0 special-case for + * get_count_order_ulong. + */ + order = fls_ulong(index); + dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n", + hash, index, order, index & ((1UL << (order - 1)) - 1)); + return &ht->t.tbl[order]->nodes[index & ((1UL << (order - 1)) - 1)]; } /* @@ -736,6 +797,7 @@ void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node iter_prev = dummy; /* We can always skip the dummy node initially */ iter = rcu_dereference(iter_prev->p.next); + assert(!is_removed(iter)); assert(iter_prev->p.reverse_hash <= node->p.reverse_hash); /* * We should never be called with dummy (start of chain) @@ -760,8 +822,6 @@ void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node new_next = flag_dummy(clear_flag(next)); else new_next = clear_flag(next); - if (is_removed(iter)) - new_next = flag_removed(new_next); (void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next); } return; @@ -770,31 +830,28 @@ void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node static int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size, struct cds_lfht_node *old_node, - struct cds_lfht_node *ret_next, + struct cds_lfht_node *old_next, struct cds_lfht_node *new_node) { - struct cds_lfht_node *dummy, *old_next; + struct cds_lfht_node *dummy, *ret_next; struct _cds_lfht_node *lookup; - int flagged = 0; - unsigned long hash, index, order; if (!old_node) /* Return -ENOENT if asked to replace NULL node */ - goto end; + return -ENOENT; assert(!is_removed(old_node)); assert(!is_dummy(old_node)); assert(!is_removed(new_node)); assert(!is_dummy(new_node)); assert(new_node != old_node); - do { + for (;;) { /* Insert after node to be replaced */ - old_next = ret_next; if (is_removed(old_next)) { /* * Too late, the old node has been removed under us * between lookup and replace. Fail. */ - goto end; + return -ENOENT; } assert(!is_dummy(old_next)); assert(new_node != clear_flag(old_next)); @@ -811,55 +868,42 @@ int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size, */ ret_next = uatomic_cmpxchg(&old_node->p.next, old_next, flag_removed(new_node)); - } while (ret_next != old_next); - - /* We performed the replacement. */ - flagged = 1; + 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. */ - hash = bit_reverse_ulong(old_node->p.reverse_hash); - assert(size > 0); - index = hash & (size - 1); - order = get_count_order_ulong(index + 1); - lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))]; + lookup = lookup_bucket(ht, size, bit_reverse_ulong(old_node->p.reverse_hash)); dummy = (struct cds_lfht_node *) lookup; _cds_lfht_gc_bucket(dummy, new_node); -end: - /* - * Only the flagging action indicated that we (and no other) - * replaced the node from the hash table. - */ - if (flagged) { - assert(is_removed(rcu_dereference(old_node->p.next))); - return 0; - } else { - return -ENOENT; - } + + assert(is_removed(rcu_dereference(old_node->p.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 -struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, - unsigned long size, - struct cds_lfht_node *node, - enum add_mode mode, int dummy) +void _cds_lfht_add(struct cds_lfht *ht, + unsigned long size, + struct cds_lfht_node *node, + struct cds_lfht_iter *unique_ret, + int dummy) { struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next, - *dummy_node, *return_node; + *return_node; struct _cds_lfht_node *lookup; - unsigned long hash, index, order; assert(!is_dummy(node)); assert(!is_removed(node)); - if (!size) { - assert(dummy); - node->p.next = flag_dummy(get_end()); - return node; /* Initial first add (head) */ - } - hash = bit_reverse_ulong(node->p.reverse_hash); + lookup = lookup_bucket(ht, size, bit_reverse_ulong(node->p.reverse_hash)); for (;;) { uint32_t chain_len = 0; @@ -867,9 +911,6 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, * iter_prev points to the non-removed node prior to the * insert location. */ - index = hash & (size - 1); - order = get_count_order_ulong(index + 1); - lookup = &ht->t.tbl[order]->nodes[index & ((!order ? 0 : (1UL << (order - 1))) - 1)]; iter_prev = (struct cds_lfht_node *) lookup; /* We can always skip the dummy node initially */ iter = rcu_dereference(iter_prev->p.next); @@ -879,19 +920,38 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, goto insert; if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash)) goto insert; + + /* dummy node is the first node of the identical-hash-value chain */ + if (dummy && clear_flag(iter)->p.reverse_hash == node->p.reverse_hash) + goto insert; + next = rcu_dereference(clear_flag(iter)->p.next); if (unlikely(is_removed(next))) goto gc_node; - if ((mode == ADD_UNIQUE || mode == ADD_REPLACE) + + /* uniquely add */ + if (unique_ret && !is_dummy(next) - && !ht->compare_fct(node->key, node->key_len, - clear_flag(iter)->key, - clear_flag(iter)->key_len)) { - if (mode == ADD_UNIQUE) - return clear_flag(iter); - else /* mode == ADD_REPLACE */ - goto replace; + && clear_flag(iter)->p.reverse_hash == node->p.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, &d_iter); + if (!d_iter.node) + goto insert; + + *unique_ret = d_iter; + return; } + /* Only account for identical reverse hash once */ if (iter_prev->p.reverse_hash != clear_flag(iter)->p.reverse_hash && !is_dummy(next)) @@ -917,21 +977,8 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, new_node) != iter) { continue; /* retry */ } else { - if (mode == ADD_REPLACE) - return_node = NULL; - else /* ADD_DEFAULT and ADD_UNIQUE */ - return_node = node; - goto gc_end; - } - - replace: - - if (!_cds_lfht_replace(ht, size, clear_flag(iter), next, - node)) { - return_node = clear_flag(iter); - goto end; /* gc already done */ - } else { - continue; /* retry */ + return_node = node; + goto end; } gc_node: @@ -943,15 +990,11 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, (void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next); /* retry */ } -gc_end: - /* Garbage collect logically removed nodes in the bucket */ - index = hash & (size - 1); - order = get_count_order_ulong(index + 1); - lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))]; - dummy_node = (struct cds_lfht_node *) lookup; - _cds_lfht_gc_bucket(dummy_node, node); end: - return return_node; + if (unique_ret) { + unique_ret->node = return_node; + /* unique_ret->next left unset, never used. */ + } } static @@ -961,11 +1004,9 @@ int _cds_lfht_del(struct cds_lfht *ht, unsigned long size, { struct cds_lfht_node *dummy, *next, *old; struct _cds_lfht_node *lookup; - int flagged = 0; - unsigned long hash, index, order; if (!node) /* Return -ENOENT if asked to delete NULL node */ - goto end; + return -ENOENT; /* logically delete the node */ assert(!is_dummy(node)); @@ -976,7 +1017,7 @@ int _cds_lfht_del(struct cds_lfht *ht, unsigned long size, next = old; if (unlikely(is_removed(next))) - goto end; + return -ENOENT; if (dummy_removal) assert(is_dummy(next)); else @@ -984,33 +1025,19 @@ int _cds_lfht_del(struct cds_lfht *ht, unsigned long size, new_next = flag_removed(next); old = uatomic_cmpxchg(&node->p.next, next, new_next); } while (old != next); - /* We performed the (logical) deletion. */ - flagged = 1; /* * 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. */ - hash = bit_reverse_ulong(node->p.reverse_hash); - assert(size > 0); - index = hash & (size - 1); - order = get_count_order_ulong(index + 1); - lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))]; + lookup = lookup_bucket(ht, size, bit_reverse_ulong(node->p.reverse_hash)); dummy = (struct cds_lfht_node *) lookup; _cds_lfht_gc_bucket(dummy, node); -end: - /* - * Only the flagging action indicated that we (and no other) - * removed the node from the hash. - */ - if (flagged) { - assert(is_removed(rcu_dereference(node->p.next))); - return 0; - } else { - return -ENOENT; - } + + assert(is_removed(rcu_dereference(node->p.next))); + return 0; } static @@ -1034,7 +1061,6 @@ void partition_resize_helper(struct cds_lfht *ht, unsigned long i, struct partition_resize_work *work; int thread, ret; unsigned long nr_threads; - pthread_t *thread_id; /* * Note: nr_cpus_mask + 1 is always power of 2. @@ -1049,7 +1075,6 @@ void partition_resize_helper(struct cds_lfht *ht, unsigned long i, } partition_len = len >> get_count_order_ulong(nr_threads); work = calloc(nr_threads, sizeof(*work)); - thread_id = calloc(nr_threads, sizeof(*thread_id)); assert(work); for (thread = 0; thread < nr_threads; thread++) { work[thread].ht = ht; @@ -1057,16 +1082,15 @@ void partition_resize_helper(struct cds_lfht *ht, unsigned long i, work[thread].len = partition_len; work[thread].start = thread * partition_len; work[thread].fct = fct; - ret = pthread_create(&thread_id[thread], ht->resize_attr, + 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(thread_id[thread], NULL); + ret = pthread_join(work[thread].thread_id, NULL); assert(!ret); } free(work); - free(thread_id); } /* @@ -1086,19 +1110,18 @@ void init_table_populate_partition(struct cds_lfht *ht, unsigned long i, { unsigned long j; + assert(i > ht->min_alloc_order); ht->cds_lfht_rcu_read_lock(); for (j = start; j < start + len; j++) { struct cds_lfht_node *new_node = (struct cds_lfht_node *) &ht->t.tbl[i]->nodes[j]; dbg_printf("init populate: i %lu j %lu hash %lu\n", - i, j, !i ? 0 : (1UL << (i - 1)) + j); + i, j, (1UL << (i - 1)) + j); new_node->p.reverse_hash = - bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j); - (void) _cds_lfht_add(ht, !i ? 0 : (1UL << (i - 1)), - new_node, ADD_DEFAULT, 1); - if (CMM_LOAD_SHARED(ht->in_progress_destroy)) - break; + bit_reverse_ulong((1UL << (i - 1)) + j); + _cds_lfht_add(ht, 1UL << (i - 1), + new_node, NULL, 1); } ht->cds_lfht_rcu_read_unlock(); } @@ -1119,25 +1142,24 @@ void init_table_populate(struct cds_lfht *ht, unsigned long i, static void init_table(struct cds_lfht *ht, - unsigned long first_order, unsigned long len_order) + unsigned long first_order, unsigned long last_order) { - unsigned long i, end_order; + unsigned long i; - dbg_printf("init table: first_order %lu end_order %lu\n", - first_order, first_order + len_order); - end_order = first_order + len_order; - for (i = first_order; i < end_order; i++) { + dbg_printf("init table: first_order %lu last_order %lu\n", + first_order, last_order); + assert(first_order > ht->min_alloc_order); + for (i = first_order; i <= last_order; i++) { unsigned long len; - len = !i ? 1 : 1UL << (i - 1); + 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->t.resize_target) < (!i ? 1 : (1UL << i))) + if (CMM_LOAD_SHARED(ht->t.resize_target) < (1UL << i)) break; - ht->t.tbl[i] = calloc(1, sizeof(struct rcu_level) - + (len * sizeof(struct _cds_lfht_node))); + ht->t.tbl[i] = calloc(1, len * sizeof(struct _cds_lfht_node)); assert(ht->t.tbl[i]); /* @@ -1150,9 +1172,9 @@ void init_table(struct cds_lfht *ht, * Update table size. */ cmm_smp_wmb(); /* populate data before RCU size */ - CMM_STORE_SHARED(ht->t.size, !i ? 1 : (1UL << i)); + CMM_STORE_SHARED(ht->t.size, 1UL << i); - dbg_printf("init new size: %lu\n", !i ? 1 : (1UL << i)); + dbg_printf("init new size: %lu\n", 1UL << i); if (CMM_LOAD_SHARED(ht->in_progress_destroy)) break; } @@ -1189,19 +1211,17 @@ void remove_table_partition(struct cds_lfht *ht, unsigned long i, { unsigned long j; + assert(i > ht->min_alloc_order); ht->cds_lfht_rcu_read_lock(); for (j = start; j < start + len; j++) { struct cds_lfht_node *fini_node = (struct cds_lfht_node *) &ht->t.tbl[i]->nodes[j]; dbg_printf("remove entry: i %lu j %lu hash %lu\n", - i, j, !i ? 0 : (1UL << (i - 1)) + j); + i, j, (1UL << (i - 1)) + j); fini_node->p.reverse_hash = - bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j); - (void) _cds_lfht_del(ht, !i ? 0 : (1UL << (i - 1)), - fini_node, 1); - if (CMM_LOAD_SHARED(ht->in_progress_destroy)) - break; + bit_reverse_ulong((1UL << (i - 1)) + j); + (void) _cds_lfht_del(ht, 1UL << (i - 1), fini_node, 1); } ht->cds_lfht_rcu_read_unlock(); } @@ -1222,18 +1242,18 @@ void remove_table(struct cds_lfht *ht, unsigned long i, unsigned long len) static void fini_table(struct cds_lfht *ht, - unsigned long first_order, unsigned long len_order) + unsigned long first_order, unsigned long last_order) { - long i, end_order; + long i; + void *free_by_rcu = NULL; - dbg_printf("fini table: first_order %lu end_order %lu\n", - first_order, first_order + len_order); - end_order = first_order + len_order; - assert(first_order > 0); - for (i = end_order - 1; i >= first_order; i--) { + dbg_printf("fini table: first_order %lu last_order %lu\n", + first_order, last_order); + assert(first_order > ht->min_alloc_order); + for (i = last_order; i >= first_order; i--) { unsigned long len; - len = !i ? 1 : 1UL << (i - 1); + len = 1UL << (i - 1); dbg_printf("fini order %lu len: %lu\n", i, len); /* Stop shrink if the resize target changes under us */ @@ -1250,6 +1270,8 @@ void fini_table(struct cds_lfht *ht, * return a logically removed node as insert position. */ ht->cds_lfht_synchronize_rcu(); + if (free_by_rcu) + free(free_by_rcu); /* * Set "removed" flag in dummy nodes about to be removed. @@ -1259,18 +1281,67 @@ void fini_table(struct cds_lfht *ht, */ remove_table(ht, i, len); - ht->cds_lfht_call_rcu(&ht->t.tbl[i]->head, cds_lfht_free_level); + free_by_rcu = ht->t.tbl[i]; dbg_printf("fini new size: %lu\n", 1UL << i); if (CMM_LOAD_SHARED(ht->in_progress_destroy)) break; } + + if (free_by_rcu) { + ht->cds_lfht_synchronize_rcu(); + free(free_by_rcu); + } +} + +static +void cds_lfht_create_dummy(struct cds_lfht *ht, unsigned long size) +{ + struct _cds_lfht_node *prev, *node; + unsigned long order, len, i, j; + + ht->t.tbl[0] = calloc(1, ht->min_alloc_size * sizeof(struct _cds_lfht_node)); + assert(ht->t.tbl[0]); + + dbg_printf("create dummy: order %lu index %lu hash %lu\n", 0, 0, 0); + ht->t.tbl[0]->nodes[0].next = flag_dummy(get_end()); + ht->t.tbl[0]->nodes[0].reverse_hash = 0; + + for (order = 1; order < get_count_order_ulong(size) + 1; order++) { + len = 1UL << (order - 1); + if (order <= ht->min_alloc_order) { + ht->t.tbl[order] = (struct rcu_level *) (ht->t.tbl[0]->nodes + len); + } else { + ht->t.tbl[order] = calloc(1, len * sizeof(struct _cds_lfht_node)); + assert(ht->t.tbl[order]); + } + + i = 0; + prev = ht->t.tbl[i]->nodes; + for (j = 0; j < len; j++) { + if (j & (j - 1)) { /* Between power of 2 */ + prev++; + } else if (j) { /* At each power of 2 */ + i++; + prev = ht->t.tbl[i]->nodes; + } + + node = &ht->t.tbl[order]->nodes[j]; + dbg_printf("create dummy: order %lu index %lu hash %lu\n", + order, j, j + len); + node->next = prev->next; + assert(is_dummy(node->next)); + node->reverse_hash = bit_reverse_ulong(j + len); + prev->next = flag_dummy((struct cds_lfht_node *)node); + } + } } struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct, cds_lfht_compare_fct compare_fct, unsigned long hash_seed, unsigned long init_size, + unsigned long min_alloc_size, int flags, void (*cds_lfht_call_rcu)(struct rcu_head *head, void (*func)(struct rcu_head *head)), @@ -1286,11 +1357,17 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct, struct cds_lfht *ht; unsigned long order; + /* min_alloc_size must be power of two */ + if (!min_alloc_size || (min_alloc_size & (min_alloc_size - 1))) + return NULL; /* init_size must be power of two */ - if (init_size && (init_size & (init_size - 1))) + if (!init_size || (init_size & (init_size - 1))) return NULL; + min_alloc_size = max(min_alloc_size, MIN_TABLE_SIZE); + init_size = max(init_size, min_alloc_size); ht = calloc(1, sizeof(struct cds_lfht)); assert(ht); + ht->flags = flags; ht->hash_fct = hash_fct; ht->compare_fct = compare_fct; ht->hash_seed = hash_seed; @@ -1303,17 +1380,15 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct, ht->cds_lfht_rcu_register_thread = cds_lfht_rcu_register_thread; ht->cds_lfht_rcu_unregister_thread = cds_lfht_rcu_unregister_thread; ht->resize_attr = attr; - ht->percpu_count = alloc_per_cpu_items_count(); + alloc_split_items_count(ht); /* this mutex should not nest in read-side C.S. */ pthread_mutex_init(&ht->resize_mutex, NULL); - order = get_count_order_ulong(max(init_size, MIN_TABLE_SIZE)) + 1; - ht->flags = flags; - ht->cds_lfht_rcu_thread_offline(); - pthread_mutex_lock(&ht->resize_mutex); - ht->t.resize_target = 1UL << (order - 1); - init_table(ht, 0, order); - pthread_mutex_unlock(&ht->resize_mutex); - ht->cds_lfht_rcu_thread_online(); + order = get_count_order_ulong(init_size); + ht->t.resize_target = 1UL << order; + ht->min_alloc_size = min_alloc_size; + ht->min_alloc_order = get_count_order_ulong(min_alloc_size); + cds_lfht_create_dummy(ht, 1UL << order); + ht->t.size = 1UL << order; return ht; } @@ -1322,17 +1397,13 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len, { struct cds_lfht_node *node, *next, *dummy_node; struct _cds_lfht_node *lookup; - unsigned long hash, reverse_hash, index, order, size; + unsigned long hash, reverse_hash, size; hash = ht->hash_fct(key, key_len, ht->hash_seed); reverse_hash = bit_reverse_ulong(hash); size = rcu_dereference(ht->t.size); - index = hash & (size - 1); - order = get_count_order_ulong(index + 1); - lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1))) - 1)]; - dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n", - hash, index, order, index & (!order ? 0 : ((1UL << (order - 1)) - 1))); + lookup = lookup_bucket(ht, size, hash); dummy_node = (struct cds_lfht_node *) lookup; /* We can always skip the dummy node initially */ node = rcu_dereference(dummy_node->p.next); @@ -1347,8 +1418,10 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len, break; } next = rcu_dereference(node->p.next); + assert(node == clear_flag(node)); if (likely(!is_removed(next)) && !is_dummy(next) + && node->p.reverse_hash == reverse_hash && likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) { break; } @@ -1438,40 +1511,46 @@ void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node) node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash); size = rcu_dereference(ht->t.size); - (void) _cds_lfht_add(ht, size, node, ADD_DEFAULT, 0); - ht_count_add(ht, size); + _cds_lfht_add(ht, size, node, NULL, 0); + ht_count_add(ht, size, hash); } struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, struct cds_lfht_node *node) { unsigned long hash, size; - struct cds_lfht_node *ret; + struct cds_lfht_iter iter; hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed); node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash); size = rcu_dereference(ht->t.size); - ret = _cds_lfht_add(ht, size, node, ADD_UNIQUE, 0); - if (ret == node) - ht_count_add(ht, size); - return ret; + _cds_lfht_add(ht, 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, struct cds_lfht_node *node) { unsigned long hash, size; - struct cds_lfht_node *ret; + struct cds_lfht_iter iter; hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed); node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash); size = rcu_dereference(ht->t.size); - ret = _cds_lfht_add(ht, size, node, ADD_REPLACE, 0); - if (ret == NULL) - ht_count_add(ht, size); - return ret; + for (;;) { + _cds_lfht_add(ht, 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, @@ -1486,13 +1565,15 @@ int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter, int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_iter *iter) { - unsigned long size; + unsigned long size, hash; int ret; size = rcu_dereference(ht->t.size); ret = _cds_lfht_del(ht, size, iter->node, 0); - if (!ret) - ht_count_del(ht, size); + if (!ret) { + hash = bit_reverse_ulong(iter->node->p.reverse_hash); + ht_count_del(ht, size, hash); + } return ret; } @@ -1528,7 +1609,12 @@ int cds_lfht_delete_dummy(struct cds_lfht *ht) bit_reverse_ulong(ht->t.tbl[order]->nodes[i].reverse_hash)); assert(is_dummy(ht->t.tbl[order]->nodes[i].next)); } - poison_free(ht->t.tbl[order]); + + if (order == ht->min_alloc_order) + poison_free(ht->t.tbl[0]); + else if (order > ht->min_alloc_order) + poison_free(ht->t.tbl[order]); + /* Nothing to delete for order < ht->min_alloc_order */ } return 0; } @@ -1542,13 +1628,14 @@ 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_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_dummy(ht); if (ret) return ret; - free_per_cpu_items_count(ht->percpu_count); + free_split_items_count(ht); if (attr) *attr = ht->resize_attr; poison_free(ht); @@ -1566,12 +1653,12 @@ void cds_lfht_count_nodes(struct cds_lfht *ht, unsigned long nr_dummy = 0; *approx_before = 0; - if (nr_cpus_mask >= 0) { + if (ht->split_count) { int i; - for (i = 0; i < nr_cpus_mask + 1; i++) { - *approx_before += uatomic_read(&ht->percpu_count[i].add); - *approx_before -= uatomic_read(&ht->percpu_count[i].del); + 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); } } @@ -1596,12 +1683,12 @@ void cds_lfht_count_nodes(struct cds_lfht *ht, } while (!is_end(node)); dbg_printf("number of dummy nodes: %lu\n", nr_dummy); *approx_after = 0; - if (nr_cpus_mask >= 0) { + if (ht->split_count) { int i; - for (i = 0; i < nr_cpus_mask + 1; i++) { - *approx_after += uatomic_read(&ht->percpu_count[i].add); - *approx_after -= uatomic_read(&ht->percpu_count[i].del); + 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); } } } @@ -1613,12 +1700,12 @@ void _do_cds_lfht_grow(struct cds_lfht *ht, { unsigned long old_order, new_order; - old_order = get_count_order_ulong(old_size) + 1; - new_order = get_count_order_ulong(new_size) + 1; - printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", - old_size, old_order, new_size, new_order); + old_order = get_count_order_ulong(old_size); + new_order = 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, new_order - old_order); + init_table(ht, old_order + 1, new_order); } /* called with resize mutex held */ @@ -1628,15 +1715,15 @@ void _do_cds_lfht_shrink(struct cds_lfht *ht, { unsigned long old_order, new_order; - new_size = max(new_size, MIN_TABLE_SIZE); - old_order = get_count_order_ulong(old_size) + 1; - new_order = get_count_order_ulong(new_size) + 1; - printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", - old_size, old_order, new_size, new_order); + new_size = max(new_size, ht->min_alloc_size); + old_order = get_count_order_ulong(old_size); + new_order = 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 dummy nodes to remove. */ - fini_table(ht, new_order, old_order - new_order); + fini_table(ht, new_order + 1, old_order); } @@ -1650,6 +1737,9 @@ void _do_cds_lfht_resize(struct cds_lfht *ht) * 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->t.resize_initiated = 1; old_size = ht->t.size; new_size = CMM_LOAD_SHARED(ht->t.resize_target); @@ -1675,7 +1765,7 @@ static void resize_target_update_count(struct cds_lfht *ht, unsigned long count) { - count = max(count, MIN_TABLE_SIZE); + count = max(count, ht->min_alloc_size); uatomic_set(&ht->t.resize_target, count); } @@ -1718,7 +1808,11 @@ void cds_lfht_resize_lazy(struct cds_lfht *ht, unsigned long size, int growth) cmm_smp_mb(); if (!CMM_LOAD_SHARED(ht->t.resize_initiated) && size < target_size) { uatomic_inc(&ht->in_progress_resize); - cmm_smp_mb(); /* increment resize count before calling it */ + 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->cds_lfht_call_rcu(&work->head, do_resize_cb); @@ -1726,8 +1820,6 @@ void cds_lfht_resize_lazy(struct cds_lfht *ht, unsigned long size, int growth) } } -#if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) - static void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size, unsigned long count) @@ -1741,12 +1833,14 @@ void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size, cmm_smp_mb(); if (!CMM_LOAD_SHARED(ht->t.resize_initiated)) { uatomic_inc(&ht->in_progress_resize); - cmm_smp_mb(); /* increment resize count before calling it */ + 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->cds_lfht_call_rcu(&work->head, do_resize_cb); CMM_STORE_SHARED(ht->t.resize_initiated, 1); } } - -#endif diff --git a/hashtable/rculfhash.h b/hashtable/rculfhash.h index 0a739ee86..008b1d49f 100644 --- a/hashtable/rculfhash.h +++ b/hashtable/rculfhash.h @@ -37,12 +37,22 @@ extern "C" { * 4-bytes boundaries because the two lower bits are used as flags. */ +/* + * _cds_lfht_node: Contains the internal pointers and reverse-hash + * value required for lookup and traversal of the hash table. + */ struct _cds_lfht_node { struct cds_lfht_node *next; /* ptr | DUMMY_FLAG | REMOVED_FLAG */ unsigned long reverse_hash; } __attribute__((aligned(4))); /* + * cds_lfht_node: Contains the full key and length required to check for + * an actual match, and also contains an rcu_head structure that is used + * by RCU to track a node through a given RCU grace period. There is an + * instance of _cds_lfht_node enclosed as a field within each + * _cds_lfht_node structure. + * * struct cds_lfht_node can be embedded into a structure (as a field). * caa_container_of() can be used to get the structure from the struct * cds_lfht_node after a lookup. @@ -56,6 +66,7 @@ struct cds_lfht_node { struct rcu_head head; }; +/* cds_lfht_iter: Used to track state while traversing a hash chain. */ struct cds_lfht_iter { struct cds_lfht_node *node, *next; }; @@ -94,6 +105,7 @@ void cds_lfht_node_init(struct cds_lfht_node *node, void *key, */ enum { CDS_LFHT_AUTO_RESIZE = (1U << 0), + CDS_LFHT_ACCOUNTING = (1U << 1), }; /* @@ -103,6 +115,7 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct, cds_lfht_compare_fct compare_fct, unsigned long hash_seed, unsigned long init_size, + unsigned long min_alloc_size, int flags, void (*cds_lfht_call_rcu)(struct rcu_head *head, void (*func)(struct rcu_head *head)), @@ -121,6 +134,7 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct, * @compare_fct: the key comparison function. * @hash_seed: the seed for hash function. * @init_size: number of nodes to allocate initially. Must be power of two. + * @min_alloc_size: the smallest allocation size to use. Must be power of two. * @flags: hash table creation flags (can be combined with bitwise or: '|'). * 0: no flags. * CDS_LFHT_AUTO_RESIZE: automatically resize hash table. @@ -136,17 +150,19 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct, * this priority level. Having lower priority for call_rcu and resize threads * does not pose any correctness issue, but the resize operations could be * starved by updates, thus leading to long hash table bucket chains. + * Threads calling this API need to be registered RCU read-side threads. */ static inline struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct, cds_lfht_compare_fct compare_fct, unsigned long hash_seed, unsigned long init_size, + unsigned long min_alloc_size, int flags, pthread_attr_t *attr) { return _cds_lfht_new(hash_fct, compare_fct, hash_seed, - init_size, flags, + init_size, min_alloc_size, flags, call_rcu, synchronize_rcu, rcu_read_lock, rcu_read_unlock, rcu_thread_offline, rcu_thread_online, rcu_register_thread, @@ -158,28 +174,36 @@ struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct, * @ht: the hash table to destroy. * @attr: (output) resize worker thread attributes, as received by cds_lfht_new. * The caller will typically want to free this pointer if dynamically - * allocated. + * allocated. The attr point can be NULL if the caller does not + * need to be informed of the value passed to cds_lfht_new(). * * Return 0 on success, negative error value on error. + * Threads calling this API need to be registered RCU read-side threads. */ int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr); /* * cds_lfht_count_nodes - count the number of nodes in the hash table. - * + * @ht: the hash table. + * @split_count_before: Sample the node count split-counter before traversal. + * @count: Traverse the hash table, count the number of nodes observed. + * @removed: Number of logically removed nodes observed during traversal. + * @split_count_after: Sample the node count split-counter after traversal. * Call with rcu_read_lock held. + * Threads calling this API need to be registered RCU read-side threads. */ void cds_lfht_count_nodes(struct cds_lfht *ht, - long *approx_before, + long *split_count_before, unsigned long *count, unsigned long *removed, - long *approx_after); + long *split_count_after); /* * cds_lfht_lookup - lookup a node by key. * * Output in "*iter". *iter->node set to NULL if not found. * Call with rcu_read_lock held. + * Threads calling this API need to be registered RCU read-side threads. */ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len, struct cds_lfht_iter *iter); @@ -194,6 +218,7 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len, * cds_lfht_next calls, and also between cds_lfht_next calls using the * node returned by a previous cds_lfht_next. * Call with rcu_read_lock held. + * Threads calling this API need to be registered RCU read-side threads. */ void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter); @@ -202,6 +227,7 @@ void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter); * * Output in "*iter". *iter->node set to NULL if table is empty. * Call with rcu_read_lock held. + * Threads calling this API need to be registered RCU read-side threads. */ void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter); @@ -211,14 +237,16 @@ void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter); * Input/Output in "*iter". *iter->node set to NULL if *iter was * pointing to the last table node. * Call with rcu_read_lock held. + * Threads calling this API need to be registered RCU read-side threads. */ void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter); /* * cds_lfht_add - add a node to the hash table. * - * Call with rcu_read_lock held. * This function supports adding redundant keys into the table. + * Call with rcu_read_lock held. + * Threads calling this API need to be registered RCU read-side threads. */ void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node); @@ -230,6 +258,7 @@ void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node); * cds_lfht_add_unique fails, the node passed as parameter should be * freed by the caller. * Call with rcu_read_lock held. + * Threads calling this API need to be registered RCU read-side threads. * * The semantic of this function is that if only this function is used * to add keys into the table, no duplicated keys should ever be @@ -246,6 +275,7 @@ struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, * was present, return NULL, which also means the operation succeeded. * This replacement operation should never fail. * Call with rcu_read_lock held. + * Threads calling this API need to be registered RCU read-side threads. * After successful replacement, a grace period must be waited for before * freeing the memory reserved for the returned node. * @@ -271,6 +301,7 @@ struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht, * Old node can be looked up with cds_lfht_lookup and cds_lfht_next. * RCU read-side lock must be held between lookup and replacement. * Call with rcu_read_lock held. + * Threads calling this API need to be registered RCU read-side threads. * After successful replacement, a grace period must be waited for before * freeing the memory reserved for the old node (which can be accessed * with cds_lfht_iter_get_node). @@ -299,6 +330,7 @@ int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter, * cds_lfht_iter_get_node. * RCU read-side lock must be held between lookup and removal. * Call with rcu_read_lock held. + * Threads calling this API need to be registered RCU read-side threads. * After successful removal, a grace period must be waited for before * freeing the memory reserved for old node (which can be accessed with * cds_lfht_iter_get_node). @@ -308,6 +340,8 @@ int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_iter *iter); /* * cds_lfht_resize - Force a hash table resize * @new_size: update to this hash table size. + * + * Threads calling this API need to be registered RCU read-side threads. */ void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size); -- 2.34.1