lfstack: Implement mutex-free stack head with transparent union (v2)

[urcu.git] / urcu / wfstack.h

diff --git a/urcu/wfstack.h b/urcu/wfstack.h
index 0e435ba6d8e899ede731739e0fb8cc41db2deaf1..fc0b44b791fcf218c56714711e235cc40465296f 100644 (file)
--- a/urcu/wfstack.h
+++ b/urcu/wfstack.h
@@ -58,6 +58,12 @@ extern "C" {
  * synchronization.
  */
 
+#define CDS_WFS_WOULDBLOCK     ((void *) -1UL)
+
+enum cds_wfs_state {
+       CDS_WFS_STATE_LAST =            (1U << 0),
+};
+
 /*
  * 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
@@ -93,6 +99,7 @@ struct cds_wfs_stack {
 
 /* Locking performed internally */
 #define cds_wfs_pop_blocking           _cds_wfs_pop_blocking
+#define cds_wfs_pop_with_state_blocking        _cds_wfs_pop_with_state_blocking
 #define cds_wfs_pop_all_blocking       _cds_wfs_pop_all_blocking
 
 /*
@@ -101,6 +108,7 @@ 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
@@ -108,6 +116,11 @@ 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_with_state_blocking      \
+                                       ___cds_wfs_pop_with_state_blocking
+#define __cds_wfs_pop_nonblocking      ___cds_wfs_pop_nonblocking
+#define __cds_wfs_pop_with_state_nonblocking   \
+                                       ___cds_wfs_pop_with_state_nonblocking
 #define __cds_wfs_pop_all              ___cds_wfs_pop_all
 
 #else /* !_LGPL_SOURCE */
@@ -147,6 +160,15 @@ extern int cds_wfs_push(struct cds_wfs_stack *s, struct cds_wfs_node *node);
  */
 extern struct cds_wfs_node *cds_wfs_pop_blocking(struct cds_wfs_stack *s);
 
+/*
+ * cds_wfs_pop_with_state_blocking: pop a node from the stack, with state.
+ *
+ * Same as cds_wfs_pop_blocking, but stores whether the stack was
+ * empty into state (CDS_WFS_STATE_LAST).
+ */
+extern struct cds_wfs_node *
+       cds_wfs_pop_with_state_blocking(struct cds_wfs_stack *s, int *state);
+
 /*
  * cds_wfs_pop_all_blocking: pop all nodes from a stack.
  *
@@ -183,6 +205,14 @@ 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 +241,33 @@ 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_with_state_blocking: pop a node from the stack, with state.
+ *
+ * Same as __cds_wfs_pop_blocking, but stores whether the stack was
+ * empty into state (CDS_WFS_STATE_LAST).
+ */
+extern struct cds_wfs_node *
+       __cds_wfs_pop_with_state_blocking(struct cds_wfs_stack *s, int *state);
+
+/*
+ * __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_with_state_nonblocking: pop a node from the stack, with state.
+ *
+ * Same as __cds_wfs_pop_nonblocking, but stores whether the stack was
+ * empty into state (CDS_WFS_STATE_LAST).
+ */
+extern struct cds_wfs_node *
+       __cds_wfs_pop_with_state_nonblocking(struct cds_wfs_stack *s,
+               int *state);
+
 /*
  * __cds_wfs_pop_all: pop all nodes from a stack.
  *