X-Git-Url: http://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu%2Frculfhash.h;h=359edb574661400d53c3a2a94c79bf185fa67eb7;hp=8ee9bdd9ebd9eb368e139b26a3ab51d167d8ea99;hb=48ed1c184a1aa1da7d84c2d0bc1b9528627248ac;hpb=f0c29ed7ca7129056f5c757a9fbcbbfa8c14da44

diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
index 8ee9bdd..359edb5 100644
--- a/urcu/rculfhash.h
+++ b/urcu/rculfhash.h
@@ -21,6 +21,8 @@
  * 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>
@@ -31,124 +33,217 @@ extern "C" {
 #endif
 
 /*
- * struct rcu_ht_node and struct _rcu_ht_node should be aligned on
- * 4-bytes boundaries because the two lower bits are used as flags.
+ * struct cds_lfht_node and struct _cds_lfht_node should be aligned on
+ * 8-bytes boundaries because the two lower bits are used as flags.
  */
 
-struct _rcu_ht_node {
-	struct rcu_ht_node *next;	/* ptr | DUMMY_FLAG | REMOVED_FLAG */
+struct _cds_lfht_node {
+	struct cds_lfht_node *next;	/* ptr | DUMMY_FLAG | GC_FLAG | REMOVED_FLAG */
 	unsigned long reverse_hash;
-};
+} __attribute__((aligned(8)));
 
-struct rcu_ht_node {
+struct cds_lfht_node {
 	/* cache-hot for iteration */
-	struct _rcu_ht_node p;          /* needs to be first field */
+	struct _cds_lfht_node p;          /* needs to be first field */
 	void *key;
 	unsigned int key_len;
 	/* cache-cold for iteration */
 	struct rcu_head head;
 };
 
-struct rcu_ht;
+struct cds_lfht;
 
 /*
  * Caution !
  * Ensure reader and writer threads are registered as urcu readers.
  */
 
-typedef unsigned long (*ht_hash_fct)(void *key, size_t length,
-				     unsigned long seed);
-typedef unsigned long (*ht_compare_fct)(void *key1, size_t key1_len,
-				        void *key2, size_t key2_len);
+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);
 
 /*
- * ht_node_init - initialize a hash table node
+ * cds_lfht_node_init - initialize a hash table node
  */
 static inline
-void ht_node_init(struct rcu_ht_node *node, void *key,
-		  size_t key_len)
+void cds_lfht_node_init(struct cds_lfht_node *node, void *key,
+			size_t key_len)
 {
 	node->key = key;
 	node->key_len = key_len;
 }
 
 /*
- * ht_new - allocate a hash table.
+ * Hash table creation flags.
+ */
+enum {
+	CDS_LFHT_AUTO_RESIZE = (1U << 0),
+};
+
+/*
+ * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
+ */
+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,
+			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.
+ * @hash_fct: the hashing function.
+ * @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.
+ * @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.
  */
-struct rcu_ht *ht_new(ht_hash_fct hash_fct,
-		      ht_compare_fct compare_fct,
-		      unsigned long hash_seed,
-		      unsigned long init_size,
-		      void (*ht_call_rcu)(struct rcu_head *head,
-				void (*func)(struct rcu_head *head)));
+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,
+			int flags,
+			pthread_attr_t *attr)
+{
+	return _cds_lfht_new(hash_fct, compare_fct, hash_seed,
+			init_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);
+}
 
 /*
- * ht_destroy - destroy a hash table.
+ * 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.
+ *
+ * Return 0 on success, negative error value on error.
  */
-int ht_destroy(struct rcu_ht *ht);
+int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
 
 /*
- * ht_count_nodes - count the number of nodes in the hash table.
+ * cds_lfht_count_nodes - count the number of nodes in the hash table.
  *
  * Call with rcu_read_lock held.
  */
-void ht_count_nodes(struct rcu_ht *ht,
-		unsigned long *count,
-		unsigned long *removed);
+void cds_lfht_count_nodes(struct cds_lfht *ht,
+			unsigned long *count,
+			unsigned long *removed);
 
 /*
- * ht_lookup - lookup a node by key.
+ * cds_lfht_lookup - lookup a node by key.
  *
- * Returns NULL if not found.
+ * Return NULL if not found.
  * Call with rcu_read_lock held.
  */
-struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key, size_t key_len);
+struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len);
 
 /*
- * ht_next - get the next item with same key (after a lookup).
+ * cds_lfht_next - get the next item with same key (after a lookup).
  *
- * Returns NULL if no following node exists with same key.
- * RCU read-side lock must be held across ht_lookup and ht_next calls, and also
- * between ht_next calls using the node returned by a previous ht_next.
- * Call with rcu_read_lock held.
+ * 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.  Call with rcu_read_lock held.
  */
-struct rcu_ht_node *ht_next(struct rcu_ht *ht, struct rcu_ht_node *node);
+struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_node *node);
 
 /*
- * ht_add - add a node to the hash table.
+ * 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.
  */
-void ht_add(struct rcu_ht *ht, struct rcu_ht_node *node);
+void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node);
 
 /*
- * ht_add_unique - add a node to hash table, if key is not present.
+ * cds_lfht_add_unique - add a node to hash table, if key is not present.
  *
- * Returns the node added upon success.
- * Returns the unique node already present upon failure. If ht_add_unique fails,
- * the node passed as parameter should be freed by the caller.
+ * 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.
+ *
+ * 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 replace (see below).
  */
-struct rcu_ht_node *ht_add_unique(struct rcu_ht *ht, struct rcu_ht_node *node);
+struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, struct cds_lfht_node *node);
 
 /*
- * ht_remove - remove node from hash table.
+ * cds_lfht_replace - replace a node within hash table.
  *
- * Node can be looked up with ht_lookup. RCU read-side lock must be held between
- * lookup and removal.
+ * 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.
+ * 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 insertion and its removal, we guarantee
+ * that the lookups will always find the key if it is replaced
+ * concurrently with the lookups. Providing this guarantee require us to
+ * pin the node to remove in place (disallowing any insertion after this
+ * node temporarily) before we can proceed to its exchange with the new
+ * node atomically. This renders the "replace" operation not strictly
+ * lock-free, because a thread crashing in the middle of the replace
+ * operation could stop progress for other updaters.
+ *
+ * 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 replacement and add_unique updates
+ * will never generate duplicated keys.
  */
-int ht_remove(struct rcu_ht *ht, struct rcu_ht_node *node);
+struct cds_lfht_node *cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_node *node);
 
 /*
- * ht_resize - Force a hash table resize
- * @growth: growth order (current size is multiplied by 2^growth)
+ * cds_lfht_del - remove node from hash table.
  *
- * Currently, only expand operation is supported (growth >= 0).
+ * Return 0 if the node is successfully removed.
+ * Node can be looked up with cds_lfht_lookup. RCU read-side lock must
+ * be held between lookup and removal.
+ * Call with rcu_read_lock held.
+ * After successful removal, a grace period must be waited for before
+ * freeing the memory reserved for node.
+ */
+int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node);
+
+/*
+ * cds_lfht_resize - Force a hash table resize
+ * @new_size: update to this hash table size.
  */
-void ht_resize(struct rcu_ht *ht, int growth);
+void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
 
 #ifdef __cplusplus
 }