X-Git-Url: https://git.lttng.org/?p=urcu.git;a=blobdiff_plain;f=urcu%2Frculfhash.h;h=0a739ee86f7d11b1e9caa4b8bbb9091dbc0ff1b9;hp=94206e363bab3f9f3c5aca02e2a37cd890b7c780;hb=6b262fd76774cdd6c7ec62d2a74515d9a28c2317;hpb=732ad076c182b3ad706cd62f8a6694f921e1bb7c diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h index 94206e3..0a739ee 100644 --- a/urcu/rculfhash.h +++ b/urcu/rculfhash.h @@ -1,63 +1,318 @@ #ifndef _URCU_RCULFHASH_H #define _URCU_RCULFHASH_H +/* + * urcu/rculfhash.h + * + * Userspace RCU library - Lock-Free RCU Hash Table + * + * Copyright 2011 - Mathieu Desnoyers + * + * 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 + * + * Include this file _after_ including your URCU flavor. + */ + #include #include -struct rcu_ht_node { - struct rcu_ht_node *next; - void *key; - size_t key_len; - unsigned long hash; +#ifdef __cplusplus +extern "C" { +#endif + +/* + * struct cds_lfht_node and struct _cds_lfht_node should be aligned on + * 4-bytes boundaries because the two lower bits are used as flags. + */ + +struct _cds_lfht_node { + struct cds_lfht_node *next; /* ptr | DUMMY_FLAG | REMOVED_FLAG */ unsigned long reverse_hash; - unsigned int dummy; - void *value; +} __attribute__((aligned(4))); + +/* + * 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. + */ +struct cds_lfht_node { + /* cache-hot for iteration */ + struct _cds_lfht_node p; /* needs to be first field */ + void *key; + unsigned int key_len; + /* cache-cold for iteration */ struct rcu_head head; }; -struct rcu_ht; +struct cds_lfht_iter { + struct cds_lfht_node *node, *next; +}; + +static inline +struct cds_lfht_node *cds_lfht_iter_get_node(struct cds_lfht_iter *iter) +{ + return iter->node; +} + +struct cds_lfht; /* * Caution ! * Ensure reader and writer threads are registered as urcu readers. */ -typedef unsigned long (*ht_hash_fct)(void *key, size_t length, - unsigned long seed); -typedef unsigned long (*ht_compare_fct)(void *key1, size_t key1_len, - void *key2, size_t key2_len); +typedef unsigned long (*cds_lfht_hash_fct)(void *key, size_t length, + unsigned long seed); +typedef unsigned long (*cds_lfht_compare_fct)(void *key1, size_t key1_len, + void *key2, size_t key2_len); +/* + * cds_lfht_node_init - initialize a hash table node + */ static inline -void ht_node_init(struct rcu_ht_node *node, void *key, - size_t key_len, void *value) +void cds_lfht_node_init(struct cds_lfht_node *node, void *key, + size_t key_len) { node->key = key; node->key_len = key_len; - node->value = value; - node->dummy = 0; } /* - * init_size must be power of two. + * Hash table creation flags. */ -struct rcu_ht *ht_new(ht_hash_fct hash_fct, - ht_compare_fct compare_fct, - unsigned long hash_seed, - unsigned long init_size, - void (*ht_call_rcu)(struct rcu_head *head, - void (*func)(struct rcu_head *head))); +enum { + CDS_LFHT_AUTO_RESIZE = (1U << 0), +}; -int ht_destroy(struct rcu_ht *ht); +/* + * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly. + */ +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 (*cds_lfht_synchronize_rcu)(void), + void (*cds_lfht_rcu_read_lock)(void), + void (*cds_lfht_rcu_read_unlock)(void), + void (*cds_lfht_rcu_thread_offline)(void), + void (*cds_lfht_rcu_thread_online)(void), + void (*cds_lfht_rcu_register_thread)(void), + void (*cds_lfht_rcu_unregister_thread)(void), + pthread_attr_t *attr); -/* Call with rcu_read_lock held. */ -struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key, size_t key_len); +/* + * cds_lfht_new - allocate a hash table. + * @hash_fct: the hashing function. + * @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. + * @flags: hash table creation flags (can be combined with bitwise or: '|'). + * 0: no flags. + * CDS_LFHT_AUTO_RESIZE: automatically resize hash table. + * @attr: optional resize worker thread attributes. NULL for default. + * + * Return NULL on error. + * Note: the RCU flavor must be already included before the hash table header. + * + * The programmer is responsible for ensuring that resize operation has a + * priority equal to hash table updater threads. It should be performed by + * specifying the appropriate priority in the pthread "attr" argument, and, + * for CDS_LFHT_AUTO_RESIZE, by ensuring that call_rcu worker threads also have + * 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. + */ +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, + int flags, + pthread_attr_t *attr) +{ + return _cds_lfht_new(hash_fct, compare_fct, hash_seed, + init_size, flags, + call_rcu, synchronize_rcu, rcu_read_lock, + rcu_read_unlock, rcu_thread_offline, + rcu_thread_online, rcu_register_thread, + rcu_unregister_thread, attr); +} -/* Call with rcu_read_lock held. */ -void ht_add(struct rcu_ht *ht, struct rcu_ht_node *node); +/* + * cds_lfht_destroy - destroy a hash table. + * @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. + * + * Return 0 on success, negative error value on error. + */ +int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr); -/* Call with rcu_read_lock held. */ -int ht_remove(struct rcu_ht *ht, struct rcu_ht_node *node); +/* + * cds_lfht_count_nodes - count the number of nodes in the hash table. + * + * Call with rcu_read_lock held. + */ +void cds_lfht_count_nodes(struct cds_lfht *ht, + long *approx_before, + unsigned long *count, + unsigned long *removed, + long *approx_after); -void ht_resize(struct rcu_ht *ht, int growth); +/* + * 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. + */ +void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len, + struct cds_lfht_iter *iter); + +/* + * cds_lfht_next_duplicate - get the next item with same key (after a lookup). + * + * Uses an iterator initialized by a lookup. + * Sets *iter-node to the following node with same key. + * Sets *iter->node to NULL if no following node exists with same key. + * RCU read-side lock must be held across cds_lfht_lookup and + * 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. + */ +void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter); + +/* + * cds_lfht_first - get the first node in the table. + * + * Output in "*iter". *iter->node set to NULL if table is empty. + * Call with rcu_read_lock held. + */ +void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter); + +/* + * cds_lfht_next - get the next node in the table. + * + * Input/Output in "*iter". *iter->node set to NULL if *iter was + * pointing to the last table node. + * Call with rcu_read_lock held. + */ +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. + */ +void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node); + +/* + * cds_lfht_add_unique - add a node to hash table, if key is not present. + * + * Return the node added upon success. + * Return the unique node already present upon failure. If + * cds_lfht_add_unique fails, the node passed as parameter should be + * freed by the caller. + * Call with rcu_read_lock held. + * + * 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 + * observable in the table. The same guarantee apply for combination of + * add_unique and add_replace (see below). + */ +struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, + struct cds_lfht_node *node); + +/* + * cds_lfht_add_replace - replace or add a node within hash table. + * + * Return the node replaced upon success. If no node matching the key + * was present, return NULL, which also means the operation succeeded. + * This replacement operation should never fail. + * Call with rcu_read_lock held. + * After successful replacement, a grace period must be waited for before + * freeing the memory reserved for the returned node. + * + * The semantic of replacement vs lookups is the following: if lookups + * are performed between a key unique insertion and its removal, we + * guarantee that the lookups and get next will always find exactly one + * instance of the key if it is replaced concurrently with the lookups. + * + * Providing this semantic allows us to ensure that replacement-only + * schemes will never generate duplicated keys. It also allows us to + * guarantee that a combination of add_replace and add_unique updates + * will never generate duplicated keys. + */ +struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht, + struct cds_lfht_node *node); + +/* + * cds_lfht_replace - replace a node pointer to by iter within hash table. + * + * Return 0 if replacement is successful, negative value otherwise. + * Replacing a NULL old node or an already removed node will fail with a + * negative value. + * 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. + * 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). + * + * The semantic of replacement vs lookups is the following: if lookups + * are performed between a key unique insertion and its removal, we + * guarantee that the lookups and get next will always find exactly one + * instance of the key if it is replaced concurrently with the lookups. + * + * Providing this semantic allows us to ensure that replacement-only + * schemes will never generate duplicated keys. It also allows us to + * guarantee that a combination of add_replace and add_unique updates + * will never generate duplicated keys. + */ +int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter, + struct cds_lfht_node *new_node); + +/* + * cds_lfht_del - remove node pointed to by iterator from hash table. + * + * Return 0 if the node is successfully removed, negative value + * otherwise. + * Replacing a NULL node or an already removed node will fail with a + * negative value. + * Node can be looked up with cds_lfht_lookup and cds_lfht_next. + * cds_lfht_iter_get_node. + * RCU read-side lock must be held between lookup and removal. + * Call with rcu_read_lock held. + * 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). + */ +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. + */ +void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size); + +#ifdef __cplusplus +} +#endif #endif /* _URCU_RCULFHASH_H */