*
* Userspace RCU library - Stack with wait-free push, blocking traversal.
*
- * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright 2010-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* 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:
*
* 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
struct cds_wfs_node node;
};
+struct __cds_wfs_stack {
+ struct cds_wfs_head *head;
+};
+
struct cds_wfs_stack {
struct cds_wfs_head *head;
pthread_mutex_t lock;
};
+/*
+ * The transparent union allows calling functions that work on both
+ * struct cds_wfs_stack and struct __cds_wfs_stack on any of those two
+ * types.
+ */
+typedef union {
+ struct __cds_wfs_stack *_s;
+ struct cds_wfs_stack *s;
+} __attribute__((__transparent_union__)) cds_wfs_stack_ptr_t;
+
#ifdef _LGPL_SOURCE
#include <urcu/static/wfstack.h>
#define cds_wfs_node_init _cds_wfs_node_init
#define cds_wfs_init _cds_wfs_init
+#define cds_wfs_destroy _cds_wfs_destroy
+#define __cds_wfs_init ___cds_wfs_init
#define cds_wfs_empty _cds_wfs_empty
#define cds_wfs_push _cds_wfs_push
/* 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
/*
* For iteration on cds_wfs_head returned by __cds_wfs_pop_all or
* cds_wfs_pop_all_blocking.
*/
-#define cds_wfs_first_blocking _cds_wfs_first_blocking
+#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
/* 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 */
extern void cds_wfs_node_init(struct cds_wfs_node *node);
/*
- * cds_wfs_init: initialize wait-free stack.
+ * cds_wfs_init: initialize wait-free stack (with lock). Pair with
+ * cds_wfs_destroy().
*/
extern void cds_wfs_init(struct cds_wfs_stack *s);
+/*
+ * cds_wfs_destroy: destroy wait-free stack (with lock). Pair with
+ * cds_wfs_init().
+ */
+extern void cds_wfs_destroy(struct cds_wfs_stack *s);
+
+/*
+ * __cds_wfs_init: initialize wait-free stack (no lock). Don't pair with
+ * any destroy function.
+ */
+extern void __cds_wfs_init(struct __cds_wfs_stack *s);
+
/*
* cds_wfs_empty: return whether wait-free stack is empty.
*
* No memory barrier is issued. No mutual exclusion is required.
*/
-extern bool cds_wfs_empty(struct cds_wfs_stack *s);
+extern bool cds_wfs_empty(cds_wfs_stack_ptr_t u_stack);
/*
* cds_wfs_push: push a node into the stack.
* Returns 0 if the stack was empty prior to adding the node.
* Returns non-zero otherwise.
*/
-extern int cds_wfs_push(struct cds_wfs_stack *s, struct cds_wfs_node *node);
+extern int cds_wfs_push(cds_wfs_stack_ptr_t u_stack, struct cds_wfs_node *node);
/*
* cds_wfs_pop_blocking: pop a node from the stack.
*/
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.
*
extern struct cds_wfs_head *cds_wfs_pop_all_blocking(struct cds_wfs_stack *s);
/*
- * cds_wfs_first_blocking: get first node of a popped stack.
+ * cds_wfs_first: get first node of a popped stack.
*
* Content written into the node before enqueue is guaranteed to be
* consistent, but no other memory ordering is ensured.
* Used by for-like iteration macros in urcu/wfstack.h:
* cds_wfs_for_each_blocking()
* cds_wfs_for_each_blocking_safe()
+ *
+ * Returns NULL if popped stack is empty, top stack node otherwise.
*/
-extern struct cds_wfs_node *cds_wfs_first_blocking(struct cds_wfs_head *head);
+extern struct cds_wfs_node *cds_wfs_first(struct cds_wfs_head *head);
/*
* cds_wfs_next_blocking: get next node of a popped stack.
* Used by for-like iteration macros in urcu/wfstack.h:
* cds_wfs_for_each_blocking()
* cds_wfs_for_each_blocking_safe()
+ *
+ * Returns NULL if reached end of popped stack, non-NULL next stack
+ * node otherwise.
*/
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.
*/
* 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking()
* and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme).
*/
-extern struct cds_wfs_node *__cds_wfs_pop_blocking(struct cds_wfs_stack *s);
+extern struct cds_wfs_node *__cds_wfs_pop_blocking(cds_wfs_stack_ptr_t u_stack);
+
+/*
+ * __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(cds_wfs_stack_ptr_t u_stack,
+ 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(cds_wfs_stack_ptr_t u_stack);
+
+/*
+ * __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(cds_wfs_stack_ptr_t u_stack,
+ int *state);
/*
* __cds_wfs_pop_all: pop all nodes from a stack.
* 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking()
* and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme).
*/
-extern struct cds_wfs_head *__cds_wfs_pop_all(struct cds_wfs_stack *s);
+extern struct cds_wfs_head *__cds_wfs_pop_all(cds_wfs_stack_ptr_t u_stack);
#endif /* !_LGPL_SOURCE */
* consistent, but no other memory ordering is ensured.
*/
#define cds_wfs_for_each_blocking(head, node) \
- for (node = cds_wfs_first_blocking(head); \
+ for (node = cds_wfs_first(head); \
node != NULL; \
node = cds_wfs_next_blocking(node))
* consistent, but no other memory ordering is ensured.
*/
#define cds_wfs_for_each_blocking_safe(head, node, n) \
- for (node = cds_wfs_first_blocking(head), \
+ for (node = cds_wfs_first(head), \
n = (node ? cds_wfs_next_blocking(node) : NULL); \
node != NULL; \
node = n, n = (node ? cds_wfs_next_blocking(node) : NULL))
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