X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=liblttng-ht%2Frculfhash.h;fp=liblttng-ht%2Frculfhash.h;h=136c7259bc45ff7d473f2b0f61f072b0b969875e;hp=0000000000000000000000000000000000000000;hb=bec399405a4667411ae06bbbcbed678e42e93a30;hpb=67cea2c94b841ee9b38ba80ab8a9eafff5f76408 diff --git a/liblttng-ht/rculfhash.h b/liblttng-ht/rculfhash.h new file mode 100644 index 000000000..136c7259b --- /dev/null +++ b/liblttng-ht/rculfhash.h @@ -0,0 +1,434 @@ +#ifndef _URCU_RCULFHASH_H +#define _URCU_RCULFHASH_H + +/* + * urcu/rculfhash.h + * + * 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 + * 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 +#include + +#include "urcu-flavor.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/* + * 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 | REMOVAL_OWNER_FLAG | BUCKET_FLAG | REMOVED_FLAG */ + unsigned long reverse_hash; +} __attribute__((aligned(8))); + +/* 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; + +/* + * Caution ! + * Ensure reader and writer threads are registered as urcu readers. + */ + +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) +{ +} + +/* + * Hash table creation flags. + */ +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. + */ +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) + * @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. + * + * 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 this API are NOT required to be registered RCU read-side + * threads. It can be called very early.(before rcu is initialized ...etc.) + */ +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, + 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. + */ +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. + */ +void cds_lfht_count_nodes(struct cds_lfht *ht, + 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. + * + * 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, unsigned long hash, + cds_lfht_match_fct match, const void *key, + struct cds_lfht_iter *iter); + +/* + * cds_lfht_next_duplicate - get the next item with same key (after a lookup). + * @ht: the hash table. + * @match: the key match function. + * @key: the current node key. + * @iter: Node, if found (output). *iter->node set to NULL if not found. + * + * 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. + * Threads calling this API need to be registered RCU read-side threads. + */ +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. + */ +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: Next node, if exists (output). *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. + */ +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. + */ +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. + * 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). + */ +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 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, + unsigned long hash, + cds_lfht_match_fct match, + const void *key, + struct cds_lfht_node *node); + +/* + * cds_lfht_replace - replace a node pointer 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. + * + * 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 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, + 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). + */ +int cds_lfht_del(struct cds_lfht *ht, 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. + */ +void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size); + +/* + * Note: cds_lfht_for_each are safe for element removal during + * iteration. + */ +#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 + +#endif /* _URCU_RCULFHASH_H */