X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=rculfhash.c;h=bff26a8d4fe668e2d4330927dcc812384aea039e;hp=359de13c82cb427a691fae8645da3adf4c5f1b08;hb=15cfbec77d2c573110cc936d5b33745d44207b50;hpb=c941bb9efd0c5b865988d46605e82c9b08c544d8 diff --git a/rculfhash.c b/rculfhash.c index 359de13..bff26a8 100644 --- a/rculfhash.c +++ b/rculfhash.c @@ -144,7 +144,6 @@ #include #include #include -#include #include #include #include @@ -768,6 +767,80 @@ void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node return; } +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 *new_node) +{ + struct cds_lfht_node *dummy, *old_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; + + 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 { + /* 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; + } + assert(!is_dummy(old_next)); + assert(new_node != clear_flag(old_next)); + new_node->p.next = clear_flag(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. + */ + 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; + + /* + * 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))]; + 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; + } +} + static struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, unsigned long size, @@ -852,36 +925,13 @@ struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, } replace: - /* Insert after node to be replaced */ - iter_prev = clear_flag(iter); - iter = next; - assert(node != clear_flag(iter)); - assert(!is_removed(iter_prev)); - assert(!is_removed(iter)); - assert(iter_prev != node); - assert(!dummy); - node->p.next = clear_flag(iter); - if (is_dummy(iter)) - new_node = flag_dummy(node); - else - new_node = node; - /* - * 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. - */ - new_node = flag_removed(new_node); - if (uatomic_cmpxchg(&iter_prev->p.next, - iter, new_node) != iter) { - continue; /* retry */ + + if (!_cds_lfht_replace(ht, size, clear_flag(iter), next, + node)) { + return_node = clear_flag(iter); + goto end; /* gc already done */ } else { - return_node = iter_prev; - goto gc_end; + continue; /* retry */ } gc_node: @@ -900,6 +950,7 @@ gc_end: 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; } @@ -913,6 +964,9 @@ int _cds_lfht_del(struct cds_lfht *ht, unsigned long size, int flagged = 0; unsigned long hash, index, order; + if (!node) /* Return -ENOENT if asked to delete NULL node */ + goto end; + /* logically delete the node */ assert(!is_dummy(node)); assert(!is_removed(node)); @@ -954,8 +1008,9 @@ end: if (flagged) { assert(is_removed(rcu_dereference(node->p.next))); return 0; - } else + } else { return -ENOENT; + } } static @@ -1280,11 +1335,11 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len, node = clear_flag(node); for (;;) { if (unlikely(is_end(node))) { - node = NULL; + node = next = NULL; break; } if (unlikely(node->p.reverse_hash > reverse_hash)) { - node = NULL; + node = next = NULL; break; } next = rcu_dereference(node->p.next); @@ -1300,7 +1355,7 @@ void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len, iter->next = next; } -void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter) +void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter) { struct cds_lfht_node *node, *next; unsigned long reverse_hash; @@ -1316,11 +1371,11 @@ void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter) for (;;) { if (unlikely(is_end(node))) { - node = NULL; + node = next = NULL; break; } if (unlikely(node->p.reverse_hash > reverse_hash)) { - node = NULL; + node = next = NULL; break; } next = rcu_dereference(node->p.next); @@ -1336,6 +1391,44 @@ void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter) iter->next = next; } +void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter) +{ + struct cds_lfht_node *node, *next; + + node = iter->node; + next = iter->next; + node = clear_flag(next); + + for (;;) { + if (unlikely(is_end(node))) { + node = next = NULL; + break; + } + next = rcu_dereference(node->p.next); + if (likely(!is_removed(next)) + && !is_dummy(next)) { + break; + } + node = clear_flag(next); + } + assert(!node || !is_dummy(rcu_dereference(node->p.next))); + iter->node = node; + iter->next = next; +} + +void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter) +{ + struct _cds_lfht_node *lookup; + + /* + * Get next after first dummy node. The first dummy node is the + * first node of the linked list. + */ + lookup = &ht->t.tbl[0]->nodes[0]; + iter->node = (struct cds_lfht_node *) lookup; + cds_lfht_next(ht, iter); +} + void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node) { unsigned long hash, size; @@ -1364,7 +1457,7 @@ struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, return ret; } -struct cds_lfht_node *cds_lfht_replace(struct cds_lfht *ht, +struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht, struct cds_lfht_node *node) { unsigned long hash, size; @@ -1380,13 +1473,23 @@ struct cds_lfht_node *cds_lfht_replace(struct cds_lfht *ht, return ret; } -int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node) +int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter, + struct cds_lfht_node *new_node) +{ + unsigned long size; + + size = rcu_dereference(ht->t.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_iter *iter) { unsigned long size; int ret; size = rcu_dereference(ht->t.size); - ret = _cds_lfht_del(ht, size, node, 0); + ret = _cds_lfht_del(ht, size, iter->node, 0); if (!ret) ht_count_del(ht, size); return ret; @@ -1452,10 +1555,10 @@ int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr) } void cds_lfht_count_nodes(struct cds_lfht *ht, - unsigned long *approx_before, + long *approx_before, unsigned long *count, unsigned long *removed, - unsigned long *approx_after) + long *approx_after) { struct cds_lfht_node *node, *next; struct _cds_lfht_node *lookup;