X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=rculfhash.c;h=6a80049ddd1f783a21e117d63437eec5771ba514;hp=1720afb61669e971968fc2cfcd994db3e6b7b8be;hb=53960c9f970e231b1ca5f53913b60d298540cf9a;hpb=8129be4e7b668906bdbb68c4d7c9fcb403ae977a diff --git a/rculfhash.c b/rculfhash.c index 1720afb..6a80049 100644 --- a/rculfhash.c +++ b/rculfhash.c @@ -1,7 +1,7 @@ /* * rculfhash.c * - * Userspace RCU library - Lock-Free Expandable RCU Hash Table + * Userspace RCU library - Lock-Free Resizable RCU Hash Table * * Copyright 2010-2011 - Mathieu Desnoyers * @@ -29,7 +29,7 @@ * symposium on Parallel algorithms and architectures, ACM Press, * (2002), 73-82. * - * Some specificities of this Lock-Free Expandable RCU Hash Table + * Some specificities of this Lock-Free Resizable RCU Hash Table * implementation: * * - RCU read-side critical section allows readers to perform hash @@ -48,9 +48,13 @@ * - An index of dummy nodes is kept. These dummy nodes are the hash * table "buckets", and they are also chained together in the * split-ordered list, which allows recursive expansion. - * - The resize operation only allows expanding the hash table. - * It is triggered either through an API call or automatically by - * detecting long chains in the add operation. + * - 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. + * - Per-CPU 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. @@ -92,6 +96,39 @@ * - 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. + * + * 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 @@ -102,6 +139,7 @@ #include #include +#include "config.h" #include #include #include @@ -118,8 +156,28 @@ #define dbg_printf(fmt, args...) #endif -#define CHAIN_LEN_TARGET 4 -#define CHAIN_LEN_RESIZE_THRESHOLD 8 +/* For testing */ +#define POISON_FREE + +/* + * Per-CPU 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 CHAIN_LEN_TARGET 1 +#define CHAIN_LEN_RESIZE_THRESHOLD 3 + +/* + * Define the minimum table size. Protects against hash table resize overload + * when too many entries are added quickly before the resize can complete. + * This is especially the case if the table could be shrinked to a size of 1. + * TODO: we might want to make the add/remove operations help the resize to + * add or remove dummy nodes when a resize is ongoing to ensure upper-bound on + * chain length. + */ +#define MIN_TABLE_SIZE 128 #ifndef max #define max(a, b) ((a) > (b) ? (a) : (b)) @@ -134,12 +192,21 @@ #define DUMMY_FLAG (1UL << 1) #define FLAGS_MASK ((1UL << 2) - 1) +struct ht_items_count { + unsigned long add, remove; +} __attribute__((aligned(CAA_CACHE_LINE_SIZE))); + +struct rcu_level { + struct rcu_head head; + struct _cds_lfht_node nodes[0]; +}; + struct rcu_table { unsigned long size; /* always a power of 2 */ unsigned long resize_target; int resize_initiated; struct rcu_head head; - struct _cds_lfht_node *tbl[0]; + struct rcu_level *tbl[0]; }; struct cds_lfht { @@ -147,10 +214,14 @@ struct cds_lfht { cds_lfht_hash_fct hash_fct; cds_lfht_compare_fct compare_fct; unsigned long hash_seed; + int flags; pthread_mutex_t resize_mutex; /* resize mutex: add/del mutex */ unsigned int in_progress_resize, in_progress_destroy; void (*cds_lfht_call_rcu)(struct rcu_head *head, void (*func)(struct rcu_head *head)); + void (*cds_lfht_synchronize_rcu)(void); + unsigned long count; /* global approximate item count */ + struct ht_items_count *percpu_count; /* per-cpu item count */ }; struct rcu_resize_work { @@ -350,13 +421,185 @@ int get_count_order_ulong(unsigned long x) return order; } +#ifdef POISON_FREE +#define poison_free(ptr) \ + do { \ + memset(ptr, 0x42, sizeof(*(ptr))); \ + free(ptr); \ + } while (0) +#else +#define poison_free(ptr) free(ptr) +#endif + static void cds_lfht_resize_lazy(struct cds_lfht *ht, struct rcu_table *t, 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, struct rcu_table *t, + unsigned long count); + +static long nr_cpus_mask = -1; + +static +struct ht_items_count *alloc_per_cpu_items_count(void) +{ + 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; + } + /* Fall-through */ + default: + return calloc(nr_cpus_mask + 1, sizeof(*count)); + } +} + +static +void free_per_cpu_items_count(struct ht_items_count *count) +{ + poison_free(count); +} + +static +int ht_get_cpu(void) +{ + int cpu; + + assert(nr_cpus_mask >= 0); + cpu = sched_getcpu(); + if (unlikely(cpu < 0)) + return cpu; + else + return cpu & nr_cpus_mask; +} + +static +void ht_count_add(struct cds_lfht *ht, struct rcu_table *t) +{ + unsigned long percpu_count; + int cpu; + + if (unlikely(!ht->percpu_count)) + return; + cpu = ht_get_cpu(); + if (unlikely(cpu < 0)) + return; + percpu_count = uatomic_add_return(&ht->percpu_count[cpu].add, 1); + if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) { + unsigned long count; + + dbg_printf("add percpu %lu\n", percpu_count); + count = uatomic_add_return(&ht->count, + 1UL << COUNT_COMMIT_ORDER); + /* If power of 2 */ + if (!(count & (count - 1))) { + if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) + < t->size) + return; + dbg_printf("add set global %lu\n", count); + cds_lfht_resize_lazy_count(ht, t, + count >> (CHAIN_LEN_TARGET - 1)); + } + } +} + +static +void ht_count_remove(struct cds_lfht *ht, struct rcu_table *t) +{ + unsigned long percpu_count; + int cpu; + + if (unlikely(!ht->percpu_count)) + return; + cpu = ht_get_cpu(); + if (unlikely(cpu < 0)) + return; + percpu_count = uatomic_add_return(&ht->percpu_count[cpu].remove, -1); + if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) { + unsigned long count; + + dbg_printf("remove percpu %lu\n", percpu_count); + count = uatomic_add_return(&ht->count, + -(1UL << COUNT_COMMIT_ORDER)); + /* If power of 2 */ + if (!(count & (count - 1))) { + if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) + >= t->size) + return; + dbg_printf("remove set global %lu\n", count); + cds_lfht_resize_lazy_count(ht, t, + count >> (CHAIN_LEN_TARGET - 1)); + } + } +} + +#else /* #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */ + +static const long nr_cpus_mask = -1; + +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, struct rcu_table *t) +{ +} + +static +void ht_count_remove(struct cds_lfht *ht, struct rcu_table *t) +{ +} + +#endif /* #else #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */ + + static void check_resize(struct cds_lfht *ht, struct rcu_table *t, 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); @@ -409,6 +652,22 @@ unsigned long _uatomic_max(unsigned long *ptr, unsigned long v) return v; } +static +void cds_lfht_free_table_cb(struct rcu_head *head) +{ + struct rcu_table *t = + caa_container_of(head, struct rcu_table, head); + poison_free(t); +} + +static +void cds_lfht_free_level(struct rcu_head *head) +{ + struct rcu_level *l = + caa_container_of(head, struct rcu_level, head); + poison_free(l); +} + /* * Remove all logically deleted nodes from a bucket up to a certain node key. */ @@ -416,12 +675,28 @@ static void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node) { struct cds_lfht_node *iter_prev, *iter, *next, *new_next; - + struct cds_lfht_node *iter_trace[64]; + unsigned long trace_idx = 0; + + memset(iter_trace, 0, sizeof(iter_trace)); + assert(!is_dummy(dummy)); + assert(!is_removed(dummy)); + assert(!is_dummy(node)); + assert(!is_removed(node)); for (;;) { + iter_trace[trace_idx++ & (64 - 1)] = (void *) 0x1; iter_prev = dummy; /* We can always skip the dummy node initially */ iter = rcu_dereference(iter_prev->p.next); + iter_trace[trace_idx++ & (64 - 1)] = iter; assert(iter_prev->p.reverse_hash <= node->p.reverse_hash); + /* + * We should never be called with dummy (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(dummy != node); for (;;) { if (unlikely(!clear_flag(iter))) return; @@ -432,6 +707,7 @@ void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node break; iter_prev = clear_flag(iter); iter = next; + iter_trace[trace_idx++ & (64 - 1)] = iter; } assert(!is_removed(iter)); if (is_dummy(iter)) @@ -439,6 +715,7 @@ void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node else new_next = clear_flag(next); (void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next); + iter_trace[trace_idx++ & (64 - 1)] = (void *) 0x2; } } @@ -451,6 +728,8 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, struct rcu_table *t, struct _cds_lfht_node *lookup; unsigned long hash, index, order; + assert(!is_dummy(node)); + assert(!is_removed(node)); if (!t->size) { assert(dummy); node->p.next = flag_dummy(NULL); @@ -466,14 +745,16 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, struct rcu_table *t, */ index = hash & (t->size - 1); order = get_count_order_ulong(index + 1); - lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)]; + lookup = &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); assert(iter_prev->p.reverse_hash <= node->p.reverse_hash); for (;;) { + /* TODO: check if removed */ if (unlikely(!clear_flag(iter))) goto insert; + /* TODO: check if removed */ if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash)) goto insert; next = rcu_dereference(clear_flag(iter)->p.next); @@ -495,6 +776,7 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, struct rcu_table *t, insert: assert(node != clear_flag(iter)); assert(!is_removed(iter_prev)); + assert(!is_removed(iter)); assert(iter_prev != node); if (!dummy) node->p.next = clear_flag(iter); @@ -522,7 +804,7 @@ gc_end: /* Garbage collect logically removed nodes in the bucket */ index = hash & (t->size - 1); order = get_count_order_ulong(index + 1); - lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)]; + lookup = &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); return node; @@ -530,7 +812,7 @@ gc_end: static int _cds_lfht_remove(struct cds_lfht *ht, struct rcu_table *t, - struct cds_lfht_node *node) + struct cds_lfht_node *node, int dummy_removal) { struct cds_lfht_node *dummy, *next, *old; struct _cds_lfht_node *lookup; @@ -538,12 +820,17 @@ int _cds_lfht_remove(struct cds_lfht *ht, struct rcu_table *t, unsigned long hash, index, order; /* logically delete the node */ + assert(!is_dummy(node)); + assert(!is_removed(node)); old = rcu_dereference(node->p.next); do { next = old; if (unlikely(is_removed(next))) goto end; - assert(!is_dummy(next)); + if (dummy_removal) + assert(is_dummy(next)); + else + assert(!is_dummy(next)); old = uatomic_cmpxchg(&node->p.next, next, flag_removed(next)); } while (old != next); @@ -557,9 +844,10 @@ int _cds_lfht_remove(struct cds_lfht *ht, struct rcu_table *t, * if found. */ hash = bit_reverse_ulong(node->p.reverse_hash); + assert(t->size > 0); index = hash & (t->size - 1); order = get_count_order_ulong(index + 1); - lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)]; + lookup = &t->tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))]; dummy = (struct cds_lfht_node *) lookup; _cds_lfht_gc_bucket(dummy, node); end: @@ -589,12 +877,14 @@ void init_table(struct cds_lfht *ht, struct rcu_table *t, len = !i ? 1 : 1UL << (i - 1); dbg_printf("init order %lu len: %lu\n", i, len); - t->tbl[i] = calloc(len, sizeof(struct _cds_lfht_node)); + t->tbl[i] = calloc(1, sizeof(struct rcu_level) + + (len * sizeof(struct _cds_lfht_node))); for (j = 0; j < len; j++) { + struct cds_lfht_node *new_node = + (struct cds_lfht_node *) &t->tbl[i]->nodes[j]; + dbg_printf("init entry: i %lu j %lu hash %lu\n", i, j, !i ? 0 : (1UL << (i - 1)) + j); - struct cds_lfht_node *new_node = - (struct cds_lfht_node *) &t->tbl[i][j]; new_node->p.reverse_hash = bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j); (void) _cds_lfht_add(ht, t, new_node, 0, 1); @@ -611,31 +901,80 @@ void init_table(struct cds_lfht *ht, struct rcu_table *t, t->resize_initiated = 0; } +static +void fini_table(struct cds_lfht *ht, struct rcu_table *t, + unsigned long first_order, unsigned long len_order) +{ + long i, end_order; + + 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); + assert(t->size == (1UL << (end_order - 1))); + for (i = end_order - 1; i >= first_order; i--) { + unsigned long j, len; + + len = !i ? 1 : 1UL << (i - 1); + dbg_printf("fini order %lu len: %lu\n", i, len); + /* + * Update table size. Need to shrink this table prior to + * removal so gc lookups use non-logically-removed dummy + * nodes. + */ + t->size = 1UL << (i - 1); + /* Unlink */ + for (j = 0; j < len; j++) { + struct cds_lfht_node *fini_node = + (struct cds_lfht_node *) &t->tbl[i]->nodes[j]; + + dbg_printf("fini entry: i %lu j %lu hash %lu\n", + i, j, !i ? 0 : (1UL << (i - 1)) + j); + fini_node->p.reverse_hash = + bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j); + (void) _cds_lfht_remove(ht, t, fini_node, 1); + if (CMM_LOAD_SHARED(ht->in_progress_destroy)) + break; + } + ht->cds_lfht_call_rcu(&t->tbl[i]->head, cds_lfht_free_level); + dbg_printf("fini new size: %lu\n", t->size); + if (CMM_LOAD_SHARED(ht->in_progress_destroy)) + break; + } + t->resize_target = t->size; + t->resize_initiated = 0; +} + 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, + int flags, void (*cds_lfht_call_rcu)(struct rcu_head *head, - void (*func)(struct rcu_head *head))) + void (*func)(struct rcu_head *head)), + void (*cds_lfht_synchronize_rcu)(void)) { struct cds_lfht *ht; unsigned long order; /* init_size must be power of two */ - if (init_size & (init_size - 1)) + if (init_size && (init_size & (init_size - 1))) return NULL; ht = calloc(1, sizeof(struct cds_lfht)); ht->hash_fct = hash_fct; ht->compare_fct = compare_fct; ht->hash_seed = hash_seed; ht->cds_lfht_call_rcu = cds_lfht_call_rcu; + ht->cds_lfht_synchronize_rcu = cds_lfht_synchronize_rcu; ht->in_progress_resize = 0; + ht->percpu_count = alloc_per_cpu_items_count(); /* 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, 1)) + 1; + order = get_count_order_ulong(max(init_size, MIN_TABLE_SIZE)) + 1; ht->t = calloc(1, sizeof(struct cds_lfht) - + (order * sizeof(struct _cds_lfht_node *))); + + (order * sizeof(struct rcu_level *))); ht->t->size = 0; + ht->flags = flags; pthread_mutex_lock(&ht->resize_mutex); init_table(ht, ht->t, 0, order); pthread_mutex_unlock(&ht->resize_mutex); @@ -655,9 +994,9 @@ struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key t = rcu_dereference(ht->t); index = hash & (t->size - 1); order = get_count_order_ulong(index + 1); - lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)]; + lookup = &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 & ((1UL << (order - 1)) - 1)); + hash, index, order, index & (!order ? 0 : ((1UL << (order - 1)) - 1))); node = (struct cds_lfht_node *) lookup; for (;;) { if (unlikely(!node)) @@ -678,6 +1017,39 @@ struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key return node; } +struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, + struct cds_lfht_node *node) +{ + struct cds_lfht_node *next; + unsigned long reverse_hash; + void *key; + size_t key_len; + + reverse_hash = node->p.reverse_hash; + key = node->key; + key_len = node->key_len; + next = rcu_dereference(node->p.next); + node = clear_flag(next); + + for (;;) { + if (unlikely(!node)) + break; + if (unlikely(node->p.reverse_hash > reverse_hash)) { + node = NULL; + break; + } + next = rcu_dereference(node->p.next); + if (likely(!is_removed(next)) + && !is_dummy(next) + && likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) { + break; + } + node = clear_flag(next); + } + assert(!node || !is_dummy(rcu_dereference(node->p.next))); + return node; +} + void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node) { struct rcu_table *t; @@ -688,6 +1060,7 @@ void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node) t = rcu_dereference(ht->t); (void) _cds_lfht_add(ht, t, node, 0, 0); + ht_count_add(ht, t); } struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, @@ -695,20 +1068,28 @@ struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, { struct rcu_table *t; unsigned long hash; + struct cds_lfht_node *ret; hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed); node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash); t = rcu_dereference(ht->t); - return _cds_lfht_add(ht, t, node, 1, 0); + ret = _cds_lfht_add(ht, t, node, 1, 0); + if (ret != node) + ht_count_add(ht, t); + return ret; } int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node) { struct rcu_table *t; + int ret; t = rcu_dereference(ht->t); - return _cds_lfht_remove(ht, t, node); + ret = _cds_lfht_remove(ht, t, node, 0); + if (!ret) + ht_count_remove(ht, t); + return ret; } static @@ -721,7 +1102,7 @@ int cds_lfht_delete_dummy(struct cds_lfht *ht) t = ht->t; /* Check that the table is empty */ - lookup = &t->tbl[0][0]; + lookup = &t->tbl[0]->nodes[0]; node = (struct cds_lfht_node *) lookup; do { node = clear_flag(node)->p.next; @@ -737,10 +1118,10 @@ int cds_lfht_delete_dummy(struct cds_lfht *ht) for (i = 0; i < len; i++) { dbg_printf("delete order %lu i %lu hash %lu\n", order, i, - bit_reverse_ulong(t->tbl[order][i].reverse_hash)); - assert(is_dummy(t->tbl[order][i].next)); + bit_reverse_ulong(t->tbl[order]->nodes[i].reverse_hash)); + assert(is_dummy(t->tbl[order]->nodes[i].next)); } - free(t->tbl[order]); + poison_free(t->tbl[order]); } return 0; } @@ -760,8 +1141,9 @@ int cds_lfht_destroy(struct cds_lfht *ht) ret = cds_lfht_delete_dummy(ht); if (ret) return ret; - free(ht->t); - free(ht); + poison_free(ht->t); + free_per_cpu_items_count(ht->percpu_count); + poison_free(ht); return ret; } @@ -779,7 +1161,7 @@ void cds_lfht_count_nodes(struct cds_lfht *ht, t = rcu_dereference(ht->t); /* Count non-dummy nodes in the table */ - lookup = &t->tbl[0][0]; + lookup = &t->tbl[0]->nodes[0]; node = (struct cds_lfht_node *) lookup; do { next = rcu_dereference(node->p.next); @@ -795,42 +1177,87 @@ void cds_lfht_count_nodes(struct cds_lfht *ht, dbg_printf("number of dummy nodes: %lu\n", nr_dummy); } +/* called with resize mutex held */ static -void cds_lfht_free_table_cb(struct rcu_head *head) +void _do_cds_lfht_grow(struct cds_lfht *ht, struct rcu_table *old_t, + unsigned long old_size, unsigned long new_size) { - struct rcu_table *t = - caa_container_of(head, struct rcu_table, head); - free(t); + unsigned long old_order, new_order; + struct rcu_table *new_t; + + 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_t = malloc(sizeof(struct cds_lfht) + + (new_order * sizeof(struct rcu_level *))); + assert(new_size > old_size); + memcpy(&new_t->tbl, &old_t->tbl, + old_order * sizeof(struct rcu_level *)); + init_table(ht, new_t, old_order, new_order - old_order); + /* Changing table and size atomically wrt lookups */ + rcu_assign_pointer(ht->t, new_t); + ht->cds_lfht_call_rcu(&old_t->head, cds_lfht_free_table_cb); } /* called with resize mutex held */ static -void _do_cds_lfht_resize(struct cds_lfht *ht) +void _do_cds_lfht_shrink(struct cds_lfht *ht, struct rcu_table *old_t, + unsigned long old_size, unsigned long new_size) { - unsigned long new_size, old_size, old_order, new_order; - struct rcu_table *new_t, *old_t; + unsigned long old_order, new_order; + struct rcu_table *new_t; - old_t = ht->t; - old_size = old_t->size; + new_size = max(new_size, MIN_TABLE_SIZE); old_order = get_count_order_ulong(old_size) + 1; - - new_size = CMM_LOAD_SHARED(old_t->resize_target); - if (old_size == new_size) - return; new_order = get_count_order_ulong(new_size) + 1; - dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", + printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n", old_size, old_order, new_size, new_order); new_t = malloc(sizeof(struct cds_lfht) - + (new_order * sizeof(struct _cds_lfht_node *))); - assert(new_size > old_size); + + (new_order * sizeof(struct rcu_level *))); + assert(new_size < old_size); memcpy(&new_t->tbl, &old_t->tbl, - old_order * sizeof(struct _cds_lfht_node *)); - init_table(ht, new_t, old_order, new_order - old_order); + new_order * sizeof(struct rcu_level *)); + new_t->size = !new_order ? 1 : (1UL << (new_order - 1)); + assert(new_t->size == new_size); + new_t->resize_target = new_t->size; + new_t->resize_initiated = 0; + /* Changing table and size atomically wrt lookups */ rcu_assign_pointer(ht->t, new_t); + + /* + * 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 dummy nodes. Otherwise their lookup will + * return a logically removed node as insert position. + */ + ht->cds_lfht_synchronize_rcu(); + + /* Unlink and remove all now-unused dummy node pointers. */ + fini_table(ht, old_t, new_order, old_order - new_order); ht->cds_lfht_call_rcu(&old_t->head, cds_lfht_free_table_cb); } + +/* called with resize mutex held */ +static +void _do_cds_lfht_resize(struct cds_lfht *ht) +{ + unsigned long new_size, old_size; + struct rcu_table *old_t; + + old_t = ht->t; + old_size = old_t->size; + new_size = CMM_LOAD_SHARED(old_t->resize_target); + if (old_size < new_size) + _do_cds_lfht_grow(ht, old_t, old_size, new_size); + else if (old_size > new_size) + _do_cds_lfht_shrink(ht, old_t, old_size, new_size); + else + CMM_STORE_SHARED(old_t->resize_initiated, 0); +} + static unsigned long resize_target_update(struct rcu_table *t, int growth_order) @@ -839,26 +1266,23 @@ unsigned long resize_target_update(struct rcu_table *t, t->size << growth_order); } -void cds_lfht_resize(struct cds_lfht *ht, int growth) +static +void resize_target_update_count(struct rcu_table *t, + unsigned long count) { - struct rcu_table *t = rcu_dereference(ht->t); - unsigned long target_size; + count = max(count, MIN_TABLE_SIZE); + uatomic_set(&t->resize_target, count); +} - if (growth < 0) { - /* - * Silently refuse to shrink hash table. (not supported) - */ - dbg_printf("shrinking hash table not supported.\n"); - return; - } +void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size) +{ + struct rcu_table *t = rcu_dereference(ht->t); - target_size = resize_target_update(t, growth); - if (t->size < target_size) { - CMM_STORE_SHARED(t->resize_initiated, 1); - pthread_mutex_lock(&ht->resize_mutex); - _do_cds_lfht_resize(ht); - pthread_mutex_unlock(&ht->resize_mutex); - } + resize_target_update_count(t, new_size); + CMM_STORE_SHARED(t->resize_initiated, 1); + pthread_mutex_lock(&ht->resize_mutex); + _do_cds_lfht_resize(ht); + pthread_mutex_unlock(&ht->resize_mutex); } static @@ -871,7 +1295,7 @@ void do_resize_cb(struct rcu_head *head) pthread_mutex_lock(&ht->resize_mutex); _do_cds_lfht_resize(ht); pthread_mutex_unlock(&ht->resize_mutex); - free(work); + poison_free(work); cmm_smp_mb(); /* finish resize before decrement */ uatomic_dec(&ht->in_progress_resize); } @@ -892,3 +1316,26 @@ void cds_lfht_resize_lazy(struct cds_lfht *ht, struct rcu_table *t, int growth) CMM_STORE_SHARED(t->resize_initiated, 1); } } + +#if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) + +static +void cds_lfht_resize_lazy_count(struct cds_lfht *ht, struct rcu_table *t, + unsigned long count) +{ + struct rcu_resize_work *work; + + if (!(ht->flags & CDS_LFHT_AUTO_RESIZE)) + return; + resize_target_update_count(t, count); + if (!CMM_LOAD_SHARED(t->resize_initiated)) { + uatomic_inc(&ht->in_progress_resize); + cmm_smp_mb(); /* increment resize count before calling it */ + work = malloc(sizeof(*work)); + work->ht = ht; + ht->cds_lfht_call_rcu(&work->head, do_resize_cb); + CMM_STORE_SHARED(t->resize_initiated, 1); + } +} + +#endif