+++ /dev/null
-/*
- * SPDX-License-Identifier: LGPL-2.1-or-later
- *
- * Copyright 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright 2011 Lai Jiangshan <laijs@cn.fujitsu.com>
- *
- * Userspace RCU library - Lock-Free RCU Hash Table
- */
-
-#ifndef _LTTNG_UST_RCULFHASH_H
-#define _LTTNG_UST_RCULFHASH_H
-
-#include <stdint.h>
-#include <pthread.h>
-#include <urcu/compiler.h>
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-struct lttng_ust_lfht;
-
-/*
- * lttng_ust_lfht_node: Contains the next pointers and reverse-hash
- * value required for lookup and traversal of the hash table.
- *
- * struct lttng_ust_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 lttng_ust_lfht_node is 8 bytes on
- * 32-bit architectures, we choose to go for simplicity and reserve
- * three bits.
- *
- * struct lttng_ust_lfht_node can be embedded into a structure (as a field).
- * caa_container_of() can be used to get the structure from the struct
- * lttng_ust_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 lttng_ust_lfht APIs.
- */
-struct lttng_ust_lfht_node {
- struct lttng_ust_lfht_node *next; /* ptr | REMOVAL_OWNER_FLAG | BUCKET_FLAG | REMOVED_FLAG */
- unsigned long reverse_hash;
-} __attribute__((aligned(8)));
-
-/* lttng_ust_lfht_iter: Used to track state while traversing a hash chain. */
-struct lttng_ust_lfht_iter {
- struct lttng_ust_lfht_node *node, *next;
-};
-
-static inline
-struct lttng_ust_lfht_node *lttng_ust_lfht_iter_get_node(struct lttng_ust_lfht_iter *iter)
-{
- return iter->node;
-}
-
-struct rcu_flavor_struct;
-
-/*
- * Caution !
- * Ensure reader and writer threads are registered as urcu readers.
- */
-
-typedef int (*lttng_ust_lfht_match_fct)(struct lttng_ust_lfht_node *node, const void *key);
-
-/*
- * lttng_ust_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 lttng_ust_lfht_node_init(struct lttng_ust_lfht_node *node __attribute__((unused)))
-{
-}
-
-/*
- * Hash table creation flags.
- */
-enum {
- LTTNG_UST_LFHT_AUTO_RESIZE = (1U << 0),
- LTTNG_UST_LFHT_ACCOUNTING = (1U << 1),
-};
-
-struct lttng_ust_lfht_mm_type {
- struct lttng_ust_lfht *(*alloc_lttng_ust_lfht)(unsigned long min_nr_alloc_buckets,
- unsigned long max_nr_buckets);
- void (*alloc_bucket_table)(struct lttng_ust_lfht *ht, unsigned long order);
- void (*free_bucket_table)(struct lttng_ust_lfht *ht, unsigned long order);
- struct lttng_ust_lfht_node *(*bucket_at)(struct lttng_ust_lfht *ht,
- unsigned long index);
-};
-
-extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_order
- __attribute__((visibility("hidden")));
-
-extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_chunk
- __attribute__((visibility("hidden")));
-
-extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_mmap
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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.
- * LTTNG_UST_LFHT_AUTO_RESIZE: automatically resize hash table.
- * LTTNG_UST_LFHT_ACCOUNTING: count the number of node addition
- * and removal in the table
- *
- * Return NULL on error.
- * Note: the RCU flavor must be already included before the hash table header.
- */
-extern struct lttng_ust_lfht *lttng_ust_lfht_new(unsigned long init_size,
- unsigned long min_nr_alloc_buckets,
- unsigned long max_nr_buckets,
- int flags,
- const struct lttng_ust_lfht_mm_type *mm)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_lfht_destroy - destroy a hash table.
- * @ht: the hash table to destroy.
- *
- * Return 0 on success, negative error value on error.
-
- * Prior to liburcu 0.10:
- * - Threads calling this API need to be registered RCU read-side
- * threads.
- * - lttng_ust_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.
- *
- * Starting from liburcu 0.10, rculfhash implements its own worker
- * thread to handle resize operations, which removes RCU requirements on
- * lttng_ust_lfht_destroy.
- */
-extern int lttng_ust_lfht_destroy(struct lttng_ust_lfht *ht)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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 lttng_ust_lfht_count_nodes(struct lttng_ust_lfht *ht,
- long *split_count_before,
- unsigned long *count,
- long *split_count_after)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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.
- * This function acts as a rcu_dereference() to read the node pointer.
- */
-extern void lttng_ust_lfht_lookup(struct lttng_ust_lfht *ht, unsigned long hash,
- lttng_ust_lfht_match_fct match, const void *key,
- struct lttng_ust_lfht_iter *iter)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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.
- *
- * Uses an iterator initialized by a lookup or traversal. Important: the
- * iterator _needs_ to be initialized before calling
- * lttng_ust_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 lttng_ust_lfht_lookup and
- * lttng_ust_lfht_next calls, and also between lttng_ust_lfht_next calls using the
- * node returned by a previous lttng_ust_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.
- */
-extern void lttng_ust_lfht_next_duplicate(struct lttng_ust_lfht *ht,
- lttng_ust_lfht_match_fct match, const void *key,
- struct lttng_ust_lfht_iter *iter)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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 lttng_ust_lfht_first(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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 lttng_ust_lfht_next(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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.
- */
-extern void lttng_ust_lfht_add(struct lttng_ust_lfht *ht, unsigned long hash,
- struct lttng_ust_lfht_node *node)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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
- * lttng_ust_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 or re-using 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 lttng_ust_lfht_node *lttng_ust_lfht_add_unique(struct lttng_ust_lfht *ht,
- unsigned long hash,
- lttng_ust_lfht_match_fct match,
- const void *key,
- struct lttng_ust_lfht_node *node)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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 or re-using 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.
- */
-extern struct lttng_ust_lfht_node *lttng_ust_lfht_add_replace(struct lttng_ust_lfht *ht,
- unsigned long hash,
- lttng_ust_lfht_match_fct match,
- const void *key,
- struct lttng_ust_lfht_node *node)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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.
- *
- * 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 lttng_ust_lfht_lookup and lttng_ust_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 or re-using the memory reserved for the old node (which can
- * be accessed with lttng_ust_lfht_iter_get_node).
- *
- * The semantic of replacement vs lookups is the same as
- * lttng_ust_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.
- */
-extern int lttng_ust_lfht_replace(struct lttng_ust_lfht *ht,
- struct lttng_ust_lfht_iter *old_iter,
- unsigned long hash,
- lttng_ust_lfht_match_fct match,
- const void *key,
- struct lttng_ust_lfht_node *new_node)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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 lttng_ust_lfht_lookup and lttng_ust_lfht_next,
- * followed by use of lttng_ust_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 or re-using the memory reserved for old node (which can be
- * accessed with lttng_ust_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 lttng_ust_lfht_del(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_node *node)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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 lttng_ust_lfht_lookup and lttng_ust_lfht_next,
- * followed by use of lttng_ust_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 lttng_ust_lfht_is_node_deleted(const struct lttng_ust_lfht_node *node)
- __attribute__((visibility("hidden")));
-
-/*
- * lttng_ust_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.
- * lttng_ust_lfht_resize should *not* be called from a RCU read-side critical
- * section.
- */
-extern void lttng_ust_lfht_resize(struct lttng_ust_lfht *ht, unsigned long new_size)
- __attribute__((visibility("hidden")));
-
-/*
- * 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 lttng_ust_lfht_for_each(ht, iter, node) \
- for (lttng_ust_lfht_first(ht, iter), \
- node = lttng_ust_lfht_iter_get_node(iter); \
- node != NULL; \
- lttng_ust_lfht_next(ht, iter), \
- node = lttng_ust_lfht_iter_get_node(iter))
-
-#define lttng_ust_lfht_for_each_duplicate(ht, hash, match, key, iter, node) \
- for (lttng_ust_lfht_lookup(ht, hash, match, key, iter), \
- node = lttng_ust_lfht_iter_get_node(iter); \
- node != NULL; \
- lttng_ust_lfht_next_duplicate(ht, match, key, iter), \
- node = lttng_ust_lfht_iter_get_node(iter))
-
-#define lttng_ust_lfht_for_each_entry(ht, iter, pos, member) \
- for (lttng_ust_lfht_first(ht, iter), \
- pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \
- __typeof__(*(pos)), member); \
- lttng_ust_lfht_iter_get_node(iter) != NULL; \
- lttng_ust_lfht_next(ht, iter), \
- pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \
- __typeof__(*(pos)), member))
-
-#define lttng_ust_lfht_for_each_entry_duplicate(ht, hash, match, key, \
- iter, pos, member) \
- for (lttng_ust_lfht_lookup(ht, hash, match, key, iter), \
- pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \
- __typeof__(*(pos)), member); \
- lttng_ust_lfht_iter_get_node(iter) != NULL; \
- lttng_ust_lfht_next_duplicate(ht, match, key, iter), \
- pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \
- __typeof__(*(pos)), member))
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* _LTTNG_UST_RCULFHASH_H */
projects / lttng-ust.git / blobdiff