* 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 <stdint.h>
* 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 */
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;
/*
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, void *key);
/*
* cds_lfht_node_init - initialize a hash table node
+ * @node: the node to initialize.
+ * @key: pointer to the key to use.
+ * @key_len: the length of the key, in bytes.
*/
static inline
void cds_lfht_node_init(struct cds_lfht_node *node, void *key,
node->key_len = key_len;
}
+/*
+ * Hash table creation flags.
+ */
+enum {
+ CDS_LFHT_AUTO_RESIZE = (1U << 0),
+ CDS_LFHT_ACCOUNTING = (1U << 1),
+};
+
+/*
+ * _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_alloc_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);
+
/*
* cds_lfht_new - allocate a hash table.
+ * @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.
+ * @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 this API need to be registered RCU read-side threads.
*/
-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,
- void (*cds_lfht_call_rcu)(struct rcu_head *head,
- void (*func)(struct rcu_head *head)));
+static inline
+struct cds_lfht *cds_lfht_new(unsigned long init_size,
+ unsigned long min_alloc_size,
+ int flags,
+ pthread_attr_t *attr)
+{
+ return _cds_lfht_new(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,
+ rcu_unregister_thread, 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);
+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,
- unsigned long *count,
- unsigned long *removed);
+ long *split_count_before,
+ unsigned long *count,
+ unsigned long *removed,
+ long *split_count_after);
/*
* cds_lfht_lookup - lookup a node by key.
+ * @ht: the hash table.
+ * @match: the key match function.
+ * @hash: the key hash.
+ * @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.
*/
-struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len);
+void cds_lfht_lookup(struct cds_lfht *ht, cds_lfht_match_fct match,
+ unsigned long hash, 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 a lookup).
+ * @ht: the hash table.
+ * @match: the key match function.
+ * @iter: Node, if found (output). *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.
+ * 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.
*/
-struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_node *node);
+void cds_lfht_next_duplicate(struct cds_lfht *ht,
+ cds_lfht_match_fct match, 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, struct cds_lfht_node *node);
+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.
+ * @match: the key match function.
+ * @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.
* 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,
+ cds_lfht_match_fct match,
+ unsigned long hash,
+ struct cds_lfht_node *node);
+
+/*
+ * cds_lfht_add_replace - replace or add a node within hash table.
+ * @ht: the hash table.
+ * @match: the key match function.
+ * @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,
+ cds_lfht_match_fct match,
+ unsigned long hash,
+ 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.
+ * @now_node: the new node to try using for replacement.
+ *
+ * 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.
+ * 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.
*/
-struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, struct cds_lfht_node *node);
+int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter,
+ struct cds_lfht_node *new_node);
/*
- * cds_lfht_remove - remove node from hash table.
+ * cds_lfht_del - remove node pointed to by iterator from hash table.
+ * @ht: the hash table.
+ * @iter: the iterator position of the node to delete.
*
- * Node can be looked up with cds_lfht_lookup. RCU read-side lock must be held between
- * lookup and removal.
+ * 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.
+ * 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_remove(struct cds_lfht *ht, struct cds_lfht_node *node);
+int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_iter *iter);
/*
* cds_lfht_resize - Force a hash table resize
- * @growth: growth order (current size is multiplied by 2^growth)
+ * @ht: the hash table.
+ * @new_size: update to this hash table size.
*
- * Currently, only expand operation is supported (growth >= 0).
+ * Threads calling this API need to be registered RCU read-side threads.
*/
-void cds_lfht_resize(struct cds_lfht *ht, int growth);
+void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
#ifdef __cplusplus
}
projects / urcu.git / blobdiff