X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=urcu%2Frculfhash.h;h=6f09ddbde7cbe25f2afd83c85652c3609512f784;hb=22731b1993177a83bf5fbefde65c949df9c0ed22;hp=2d8a3104d7c18f5e94a5677c5fcca9870363b12d;hpb=3a9c66db35077a0437810157ba362a68262048de;p=urcu.git

diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
index 2d8a310..6f09ddb 100644
--- a/urcu/rculfhash.h
+++ b/urcu/rculfhash.h
@@ -132,7 +132,8 @@ struct cds_lfht *_cds_lfht_new(unsigned long init_size,
  * @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)
+ *                  (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.
@@ -175,6 +176,12 @@ struct cds_lfht *cds_lfht_new(unsigned long init_size,
  *
  * 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 call_rcu thread context
+ * neither.
+ * In userspace RCU 0.7.x, for QSBR RCU flavor, cds_lfht_destroy() has a
+ * side-effect: it puts the caller thread in "online" state. This will
+ * be fixed in userspace RCU 0.8.x.
  */
 int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
 
@@ -203,6 +210,7 @@ void cds_lfht_count_nodes(struct cds_lfht *ht,
  *
  * 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.
  */
 void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
 		cds_lfht_match_fct match, const void *key,
@@ -226,6 +234,7 @@ void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
  * 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.
  */
 void cds_lfht_next_duplicate(struct cds_lfht *ht,
 		cds_lfht_match_fct match, const void *key,
@@ -239,6 +248,7 @@ void cds_lfht_next_duplicate(struct cds_lfht *ht,
  * 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.
  */
 void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter);
 
@@ -252,6 +262,7 @@ void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter);
  * 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.
  */
 void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter);
 
@@ -264,6 +275,8 @@ void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter);
  * 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, unsigned long hash,
 		struct cds_lfht_node *node);
@@ -288,6 +301,12 @@ void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
  * 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.
  */
 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
 		unsigned long hash,
@@ -321,6 +340,9 @@ struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
  * 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_replace(struct cds_lfht *ht,
 		unsigned long hash,
@@ -352,6 +374,10 @@ struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
  *
  * 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_replace(struct cds_lfht *ht,
 		struct cds_lfht_iter *old_iter,
@@ -377,6 +403,9 @@ int cds_lfht_replace(struct cds_lfht *ht,
  * 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.
  */
 int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node);
 
@@ -391,6 +420,7 @@ int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node);
  * 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.
  */
 int cds_lfht_is_node_deleted(struct cds_lfht_node *node);
 
@@ -400,6 +430,12 @@ int cds_lfht_is_node_deleted(struct cds_lfht_node *node);
  * @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.
+ * In userspace RCU 0.7.x, for QSBR RCU flavor, cds_lfht_resize() has a
+ * side-effect: it puts the caller thread in "online" state. This will
+ * be fixed in userspace RCU 0.8.x.
  */
 void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
 
@@ -407,6 +443,7 @@ 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),					\
@@ -425,21 +462,21 @@ void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
 #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);	\
+					__typeof__(*(pos)), member);	\
 		&(pos)->member != NULL;					\
 		cds_lfht_next(ht, iter),				\
 			pos = caa_container_of(cds_lfht_iter_get_node(iter), \
-					typeof(*(pos)), member))
+					__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);	\
+					__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))
+					__typeof__(*(pos)), member))
 
 #ifdef __cplusplus
 }