X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu%2Frculfhash.h;h=7a411ad688ee92cbd753a7f04f798f355179beca;hp=8f501ea29b7b1e549c9b2d87f9ecf2e769251af0;hb=28d5c1b5f2bdbb630c4aafa35c9b6e0d58542c73;hpb=01dbfa62037e08aa2d08ab0e721267ccdd99b947 diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h index 8f501ea..7a411ad 100644 --- a/urcu/rculfhash.h +++ b/urcu/rculfhash.h @@ -7,6 +7,7 @@ * Userspace RCU library - Lock-Free RCU Hash Table * * Copyright 2011 - Mathieu Desnoyers + * Copyright 2011 - Lai Jiangshan * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public @@ -21,34 +22,57 @@ * 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 #include +#include #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. + * cds_lfht_node: Contains the next pointers and reverse-hash + * value required for lookup and traversal of the hash table. + * + * struct cds_lfht_node should be aligned on 8-bytes boundaries because + * the three lower bits are used as flags. It is worth noting that the + * information contained within these three bits could be represented on + * two bits by re-using the same bit for REMOVAL_OWNER_FLAG and + * BUCKET_FLAG. This can be done if we ensure that no iterator nor + * updater check the BUCKET_FLAG after it detects that the REMOVED_FLAG + * is set. Given the minimum size of struct cds_lfht_node is 8 bytes on + * 32-bit architectures, we choose to go for simplicity and reserve + * three bits. + * + * 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. + * + * The structure which embeds it typically holds the key (or key-value + * pair) of the object. The caller code is responsible for calculation + * of the hash value for cds_lfht APIs. */ - -struct _cds_lfht_node { - struct cds_lfht_node *next; /* ptr | DUMMY_FLAG | REMOVED_FLAG */ +struct cds_lfht_node { + struct cds_lfht_node *next; /* ptr | REMOVAL_OWNER_FLAG | BUCKET_FLAG | REMOVED_FLAG */ unsigned long reverse_hash; -}; +} __attribute__((aligned(8))); -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; +/* cds_lfht_iter: Used to track state while traversing a hash chain. */ +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; /* @@ -56,20 +80,18 @@ struct cds_lfht; * Ensure reader and writer threads are registered as urcu readers. */ -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); +typedef int (*cds_lfht_match_fct)(struct cds_lfht_node *node, const void *key); /* * cds_lfht_node_init - initialize a hash table node + * @node: the node to initialize. + * + * This function is kept to be eventually used for debugging purposes + * (detection of memory corruption). */ static inline -void cds_lfht_node_init(struct cds_lfht_node *node, void *key, - size_t key_len) +void cds_lfht_node_init(struct cds_lfht_node *node) { - node->key = key; - node->key_len = key_len; } /* @@ -77,91 +99,393 @@ void cds_lfht_node_init(struct cds_lfht_node *node, void *key, */ enum { CDS_LFHT_AUTO_RESIZE = (1U << 0), + CDS_LFHT_ACCOUNTING = (1U << 1), +}; + +struct cds_lfht_mm_type { + struct cds_lfht *(*alloc_cds_lfht)(unsigned long min_nr_alloc_buckets, + unsigned long max_nr_buckets); + void (*alloc_bucket_table)(struct cds_lfht *ht, unsigned long order); + void (*free_bucket_table)(struct cds_lfht *ht, unsigned long order); + struct cds_lfht_node *(*bucket_at)(struct cds_lfht *ht, + unsigned long index); }; +extern const struct cds_lfht_mm_type cds_lfht_mm_order; +extern const struct cds_lfht_mm_type cds_lfht_mm_chunk; +extern const struct cds_lfht_mm_type cds_lfht_mm_mmap; + +/* + * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly. + */ +extern +struct cds_lfht *_cds_lfht_new(unsigned long init_size, + unsigned long min_nr_alloc_buckets, + unsigned long max_nr_buckets, + int flags, + const struct cds_lfht_mm_type *mm, + const struct rcu_flavor_struct *flavor, + pthread_attr_t *attr); + /* * cds_lfht_new - allocate a hash table. + * @init_size: number of buckets to allocate initially. Must be power of two. + * @min_nr_alloc_buckets: the minimum number of allocated buckets. + * (must be power of two) + * @max_nr_buckets: the maximum number of hash table buckets allowed. + * (must be power of two, 0 is accepted, means + * "infinite") + * @flags: hash table creation flags (can be combined with bitwise or: '|'). + * 0: no flags. + * CDS_LFHT_AUTO_RESIZE: automatically resize hash table. + * CDS_LFHT_ACCOUNTING: count the number of node addition + * and removal in the table + * @attr: optional resize worker thread attributes. NULL for default. * - * init_size must be power of two. * 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. + * Threads calling cds_lfht_new are NOT required to be registered RCU + * read-side threads. It can be called very early. (e.g. before RCU is + * initialized) */ -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, +static inline +struct cds_lfht *cds_lfht_new(unsigned long init_size, + unsigned long min_nr_alloc_buckets, + unsigned long max_nr_buckets, 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)); + pthread_attr_t *attr) +{ + return _cds_lfht_new(init_size, min_nr_alloc_buckets, max_nr_buckets, + flags, NULL, &rcu_flavor, attr); +} /* * 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. 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. + * cds_lfht_destroy should *not* be called from a RCU read-side critical + * section. It should *not* be called from a call_rcu thread context + * neither. */ -int cds_lfht_destroy(struct cds_lfht *ht); +extern +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. + * @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. */ +extern void cds_lfht_count_nodes(struct cds_lfht *ht, - unsigned long *count, - unsigned long *removed); + long *split_count_before, + unsigned long *count, + long *split_count_after); /* * cds_lfht_lookup - lookup a node by key. + * @ht: the hash table. + * @hash: the key hash. + * @match: the key match function. + * @key: the current node key. + * @iter: node, if found (output). *iter->node set to NULL if not found. * - * Return NULL if not found. * Call with rcu_read_lock held. + * Threads calling this API need to be registered RCU read-side threads. + * This function acts as a rcu_dereference() to read the node pointer. */ -struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len); +extern +void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash, + cds_lfht_match_fct match, const void *key, + 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 iterator. + * @ht: the hash table. + * @match: the key match function. + * @key: the current node key. + * @iter: input: current iterator. + * output: node, if found. *iter->node set to NULL if not found. * - * Return 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. + * Uses an iterator initialized by a lookup or traversal. Important: the + * iterator _needs_ to be initialized before calling + * cds_lfht_next_duplicate. + * 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. + * Threads calling this API need to be registered RCU read-side threads. + * This function acts as a rcu_dereference() to read the node pointer. */ -struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_node *node); +extern +void cds_lfht_next_duplicate(struct cds_lfht *ht, + cds_lfht_match_fct match, const void *key, + struct cds_lfht_iter *iter); + +/* + * cds_lfht_first - get the first node in the table. + * @ht: the hash table. + * @iter: First node, if exists (output). *iter->node set to NULL if not found. + * + * 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. + * This function acts as a rcu_dereference() to read the node pointer. + */ +extern +void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter); + +/* + * cds_lfht_next - get the next node in the table. + * @ht: the hash table. + * @iter: input: current iterator. + * output: next node, if exists. *iter->node set to NULL if not found. + * + * 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. + * This function acts as a rcu_dereference() to read the node pointer. + */ +extern +void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter); /* * cds_lfht_add - add a node to the hash table. + * @ht: the hash table. + * @hash: the key hash. + * @node: the node to add. * + * 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. + * This function issues a full memory barrier before and after its + * atomic commit. */ -void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node); +extern +void cds_lfht_add(struct cds_lfht *ht, unsigned long hash, + struct cds_lfht_node *node); /* * cds_lfht_add_unique - add a node to hash table, if key is not present. + * @ht: the hash table. + * @hash: the node's hash. + * @match: the key match function. + * @key: the node's key. + * @node: the node to try adding. * * 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. + * 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. In this case, the caller does NOT need to wait + * for a grace period before freeing the node. + * 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 + * observable in the table. The same guarantee apply for combination of + * add_unique and add_replace (see below). + * + * Upon success, this function issues a full memory barrier before and + * after its atomic commit. Upon failure, this function acts like a + * simple lookup operation: it acts as a rcu_dereference() to read the + * node pointer. The failure case does not guarantee any other memory + * barrier. + */ +extern +struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, + unsigned long hash, + cds_lfht_match_fct match, + const void *key, + struct cds_lfht_node *node); + +/* + * cds_lfht_add_replace - replace or add a node within hash table. + * @ht: the hash table. + * @hash: the node's hash. + * @match: the key match function. + * @key: the node's key. + * @node: the node to add. + * + * 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. + * 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. + * + * The semantic of replacement vs lookups and traversals is the + * following: if lookups and traversals are performed between a key + * unique insertion and its removal, we guarantee that the lookups and + * traversals 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. + * + * This function issues a full memory barrier before and after its + * atomic commit. */ -struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, struct cds_lfht_node *node); +extern +struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht, + unsigned long hash, + cds_lfht_match_fct match, + const void *key, + struct cds_lfht_node *node); /* - * cds_lfht_remove - remove node from hash table. + * cds_lfht_replace - replace a node pointed to by iter within hash table. + * @ht: the hash table. + * @old_iter: the iterator position of the node to replace. + * @hash: the node's hash. + * @match: the key match function. + * @key: the node's key. + * @new_node: the new node to use as replacement. * - * Node can be looked up with cds_lfht_lookup. RCU read-side lock must be held between - * lookup and removal. + * Return 0 if replacement is successful, negative value otherwise. + * Replacing a NULL old node or an already removed node will fail with + * -ENOENT. + * If the hash or value of the node to replace and the new node differ, + * this function returns -EINVAL without proceeding to the replacement. + * 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). + * + * The semantic of replacement vs lookups is the same as + * cds_lfht_add_replace(). + * + * Upon success, this function issues a full memory barrier before and + * after its atomic commit. Upon failure, this function does not issue + * any memory barrier. */ -int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node); +extern +int cds_lfht_replace(struct cds_lfht *ht, + struct cds_lfht_iter *old_iter, + unsigned long hash, + cds_lfht_match_fct match, + const void *key, + struct cds_lfht_node *new_node); + +/* + * cds_lfht_del - remove node pointed to by iterator from hash table. + * @ht: the hash table. + * @node: the node to delete. + * + * Return 0 if the node is successfully removed, negative value + * otherwise. + * Deleting 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, + * followed by use of 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). + * Upon success, this function issues a full memory barrier before and + * after its atomic commit. Upon failure, this function does not issue + * any memory barrier. + */ +extern +int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node); + +/* + * cds_lfht_is_node_deleted - query whether a node is removed from hash table. + * + * Return non-zero if the node is deleted from the hash table, 0 + * otherwise. + * Node can be looked up with cds_lfht_lookup and cds_lfht_next, + * followed by use of cds_lfht_iter_get_node. + * RCU read-side lock must be held between lookup and call to this + * function. + * Call with rcu_read_lock held. + * Threads calling this API need to be registered RCU read-side threads. + * This function does not issue any memory barrier. + */ +extern +int cds_lfht_is_node_deleted(struct cds_lfht_node *node); /* * cds_lfht_resize - Force a hash table resize + * @ht: the hash table. * @new_size: update to this hash table size. + * + * Threads calling this API need to be registered RCU read-side threads. + * This function does not (necessarily) issue memory barriers. + * cds_lfht_resize should *not* be called from a RCU read-side critical + * section. */ +extern void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size); +/* + * Note: it is safe to perform element removal (del), replacement, or + * any hash table update operation during any of the following hash + * table traversals. + * These functions act as rcu_dereference() to read the node pointers. + */ +#define cds_lfht_for_each(ht, iter, node) \ + for (cds_lfht_first(ht, iter), \ + node = cds_lfht_iter_get_node(iter); \ + node != NULL; \ + cds_lfht_next(ht, iter), \ + node = cds_lfht_iter_get_node(iter)) + +#define cds_lfht_for_each_duplicate(ht, hash, match, key, iter, node) \ + for (cds_lfht_lookup(ht, hash, match, key, iter), \ + node = cds_lfht_iter_get_node(iter); \ + node != NULL; \ + cds_lfht_next_duplicate(ht, match, key, iter), \ + node = cds_lfht_iter_get_node(iter)) + +#define cds_lfht_for_each_entry(ht, iter, pos, member) \ + for (cds_lfht_first(ht, iter), \ + pos = caa_container_of(cds_lfht_iter_get_node(iter), \ + __typeof__(*(pos)), member); \ + &(pos)->member != NULL; \ + cds_lfht_next(ht, iter), \ + pos = caa_container_of(cds_lfht_iter_get_node(iter), \ + __typeof__(*(pos)), member)) + +#define cds_lfht_for_each_entry_duplicate(ht, hash, match, key, \ + iter, pos, member) \ + for (cds_lfht_lookup(ht, hash, match, key, iter), \ + pos = caa_container_of(cds_lfht_iter_get_node(iter), \ + __typeof__(*(pos)), member); \ + &(pos)->member != NULL; \ + cds_lfht_next_duplicate(ht, match, key, iter), \ + pos = caa_container_of(cds_lfht_iter_get_node(iter), \ + __typeof__(*(pos)), member)) + #ifdef __cplusplus } #endif