wfstack: implement nonblocking pop and next

[urcu.git] / urcu / wfstack.h

diff --git a/urcu/wfstack.h b/urcu/wfstack.h
index 0e435ba6d8e899ede731739e0fb8cc41db2deaf1..03fee8fb63f74bb3ca8a110e0c8eb971e5ba6937 100644 (file)
--- a/urcu/wfstack.h
+++ b/urcu/wfstack.h
@@ -58,6 +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
@@ -183,6 +185,14 @@ 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.
  */
@@ -211,6 +221,14 @@ 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.
  *