X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=hashtable%2Frculfhash.h;h=008b1d49f55ae86ae4bcdf86c2ce2a8c0a1c7617;hp=860ef3d1c2d05e3516ec4a8849c9d47b39f1371f;hb=d6b189345152f407360bc287997d38d30054bd2c;hpb=fa68aa62ac4200144504075ef9186e961df2c263 diff --git a/hashtable/rculfhash.h b/hashtable/rculfhash.h index 860ef3d1c..008b1d49f 100644 --- a/hashtable/rculfhash.h +++ b/hashtable/rculfhash.h @@ -37,11 +37,26 @@ 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. + */ struct cds_lfht_node { /* cache-hot for iteration */ struct _cds_lfht_node p; /* needs to be first field */ @@ -51,6 +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; }; @@ -89,6 +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), }; /* @@ -98,6 +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)), @@ -116,6 +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. @@ -131,17 +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, @@ -153,34 +174,42 @@ 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); /* - * cds_lfht_next - get the next item with same key (after a lookup). + * 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. @@ -189,14 +218,35 @@ 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); + +/* + * 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. + * 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); + +/* + * 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. + * 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); @@ -208,6 +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 @@ -224,6 +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. * @@ -249,6 +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). @@ -277,6 +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). @@ -286,6 +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);