urcu: avoid false sharing for rcu_gp_ctr

[urcu.git] / urcu / wfstack.h

diff --git a/urcu/wfstack.h b/urcu/wfstack.h
index 0adf392f7b317210befb027949d6d6205a133e53..34ddb3f3e665465aa22b83fff4d7a2cdf8a7d385 100644 (file)
--- a/urcu/wfstack.h
+++ b/urcu/wfstack.h
@@ -38,9 +38,10 @@ extern "C" {
  * Stack implementing push, pop, pop_all operations, as well as iterator
  * on the stack head returned by pop_all.
  *
- * Wait-free operations: cds_wfs_push, __cds_wfs_pop_all.
- * Blocking operations: cds_wfs_pop, cds_wfs_pop_all, iteration on stack
- *                      head returned by pop_all.
+ * Wait-free operations: cds_wfs_push, __cds_wfs_pop_all, cds_wfs_empty,
+ *                       cds_wfs_first.
+ * Blocking operations: cds_wfs_pop, cds_wfs_pop_all, cds_wfs_next,
+ *                      iteration on stack head returned by pop_all.
  *
  * Synchronization table:
  *
@@ -57,6 +58,8 @@ extern "C" {
  * synchronization.
  */
 
+#define CDS_WFS_WOULDBLOCK     ((void *) -1UL)
+
 /*
  * struct cds_wfs_node is returned by __cds_wfs_pop, and also used as
  * iterator on stack. It is not safe to dereference the node next
@@ -100,6 +103,7 @@ struct cds_wfs_stack {
  */
 #define cds_wfs_first                  _cds_wfs_first
 #define cds_wfs_next_blocking          _cds_wfs_next_blocking
+#define cds_wfs_next_nonblocking       _cds_wfs_next_nonblocking
 
 /* Pop locking with internal mutex */
 #define cds_wfs_pop_lock               _cds_wfs_pop_lock
@@ -107,6 +111,7 @@ struct cds_wfs_stack {
 
 /* Synchronization ensured by the caller. See synchronization table. */
 #define __cds_wfs_pop_blocking         ___cds_wfs_pop_blocking
+#define __cds_wfs_pop_nonblocking      ___cds_wfs_pop_nonblocking
 #define __cds_wfs_pop_all              ___cds_wfs_pop_all
 
 #else /* !_LGPL_SOURCE */
@@ -182,6 +187,14 @@ extern struct cds_wfs_node *cds_wfs_first(struct cds_wfs_head *head);
  */
 extern struct cds_wfs_node *cds_wfs_next_blocking(struct cds_wfs_node *node);
 
+/*
+ * cds_wfs_next_nonblocking: get next node of a popped stack.
+ *
+ * Same as cds_wfs_next_blocking, but returns CDS_WFS_WOULDBLOCK if it
+ * needs to block.
+ */
+extern struct cds_wfs_node *cds_wfs_next_nonblocking(struct cds_wfs_node *node);
+
 /*
  * cds_wfs_pop_lock: lock stack pop-protection mutex.
  */
@@ -210,6 +223,14 @@ extern void cds_wfs_pop_unlock(struct cds_wfs_stack *s);
  */
 extern struct cds_wfs_node *__cds_wfs_pop_blocking(struct cds_wfs_stack *s);
 
+/*
+ * __cds_wfs_pop_nonblocking: pop a node from the stack.
+ *
+ * Same as __cds_wfs_pop_blocking, but returns CDS_WFS_WOULDBLOCK if
+ * it needs to block.
+ */
+extern struct cds_wfs_node *__cds_wfs_pop_nonblocking(struct cds_wfs_stack *s);
+
 /*
  * __cds_wfs_pop_all: pop all nodes from a stack.
  *