extern "C" {
#endif
+#include <stdbool.h>
+#include <pthread.h>
+
+/*
+ * Lock-free stack.
+ *
+ * Stack implementing push, pop, pop_all operations, as well as iterator
+ * on the stack head returned by pop_all.
+ *
+ * Synchronization table:
+ *
+ * External synchronization techniques described in the API below is
+ * required between pairs marked with "X". No external synchronization
+ * required between pairs marked with "-".
+ *
+ * cds_lfs_push __cds_lfs_pop __cds_lfs_pop_all
+ * cds_lfs_push - - -
+ * __cds_lfs_pop - X X
+ * __cds_lfs_pop_all - X -
+ *
+ * cds_lfs_pop_blocking and cds_lfs_pop_all_blocking use an internal
+ * mutex to provide synchronization.
+ */
+
+/*
+ * struct cds_lfs_node is returned by cds_lfs_pop, and also used as
+ * iterator on stack. It is not safe to dereference the node next
+ * pointer when returned by cds_lfs_pop.
+ */
struct cds_lfs_node {
struct cds_lfs_node *next;
};
+/*
+ * struct cds_lfs_head is returned by __cds_lfs_pop_all, and can be used
+ * to begin iteration on the stack. "node" needs to be the first field
+ * of cds_lfs_head, so the end-of-stack pointer value can be used for
+ * both types.
+ */
+struct cds_lfs_head {
+ struct cds_lfs_node node;
+};
+
+struct __cds_lfs_stack {
+ struct cds_lfs_head *head;
+};
+
struct cds_lfs_stack {
- struct cds_lfs_node *head;
+ struct cds_lfs_head *head;
+ pthread_mutex_t lock;
};
+/*
+ * The transparent union allows calling functions that work on both
+ * struct cds_lfs_stack and struct __cds_lfs_stack on any of those two
+ * types.
+ */
+typedef union __attribute__((__transparent_union__)) {
+ struct __cds_lfs_stack *_s;
+ struct cds_lfs_stack *s;
+} cds_lfs_stack_ptr_t;
+
#ifdef _LGPL_SOURCE
#include <urcu/static/lfstack.h>
#define cds_lfs_node_init _cds_lfs_node_init
#define cds_lfs_init _cds_lfs_init
+#define __cds_lfs_init ___cds_lfs_init
+#define cds_lfs_empty _cds_lfs_empty
#define cds_lfs_push _cds_lfs_push
-#define cds_lfs_pop _cds_lfs_pop
+
+/* Locking performed internally */
+#define cds_lfs_pop_blocking _cds_lfs_pop_blocking
+#define cds_lfs_pop_all_blocking _cds_lfs_pop_all_blocking
+
+/* Synchronize pop with internal mutex */
+#define cds_lfs_pop_lock _cds_lfs_pop_lock
+#define cds_lfs_pop_unlock _cds_lfs_pop_unlock
+
+/* Synchronization ensured by the caller. See synchronization table. */
+#define __cds_lfs_pop ___cds_lfs_pop
+#define __cds_lfs_pop_all ___cds_lfs_pop_all
#else /* !_LGPL_SOURCE */
+/*
+ * cds_lfs_node_init: initialize lock-free stack node.
+ */
extern void cds_lfs_node_init(struct cds_lfs_node *node);
+
+/*
+ * cds_lfs_init: initialize lock-free stack.
+ */
extern void cds_lfs_init(struct cds_lfs_stack *s);
+/*
+ * __cds_lfs_init: initialize lock-free stack.
+ */
+extern void __cds_lfs_init(struct __cds_lfs_stack *s);
+
+/*
+ * cds_lfs_empty: return whether lock-free stack is empty.
+ *
+ * No memory barrier is issued. No mutual exclusion is required.
+ */
+extern bool cds_lfs_empty(cds_lfs_stack_ptr_t s);
+
/*
* cds_lfs_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_lfs_push(struct cds_lfs_stack *s,
+extern bool cds_lfs_push(cds_lfs_stack_ptr_t s,
struct cds_lfs_node *node);
/*
- * cds_lfs_pop: pop a node from the stack.
+ * cds_lfs_pop_blocking: pop a node from the stack.
+ *
+ * Calls __cds_lfs_pop with an internal pop mutex held.
+ */
+extern struct cds_lfs_node *cds_lfs_pop_blocking(struct cds_lfs_stack *s);
+
+/*
+ * cds_lfs_pop_all_blocking: pop all nodes from a stack.
+ *
+ * Calls __cds_lfs_pop_all with an internal pop mutex held.
+ */
+extern struct cds_lfs_head *cds_lfs_pop_all_blocking(struct cds_lfs_stack *s);
+
+/*
+ * cds_lfs_pop_lock: lock stack pop-protection mutex.
+ */
+extern void cds_lfs_pop_lock(struct cds_lfs_stack *s);
+
+/*
+ * cds_lfs_pop_unlock: unlock stack pop-protection mutex.
+ */
+extern void cds_lfs_pop_unlock(struct cds_lfs_stack *s);
+
+/*
+ * __cds_lfs_pop: pop a node from the stack.
*
* Returns NULL if stack is empty.
*
- * cds_lfs_pop needs to be synchronized using one of the following
+ * __cds_lfs_pop needs to be synchronized using one of the following
* techniques:
*
- * 1) Calling cds_lfs_pop under rcu read lock critical section. The
+ * 1) Calling __cds_lfs_pop under rcu read lock critical section. The
* caller must wait for a grace period to pass before freeing the
* returned node or modifying the cds_lfs_node structure.
- * 2) Using mutual exclusion (e.g. mutexes) to protect cds_lfs_pop
- * callers.
- * 3) Ensuring that only ONE thread can call cds_lfs_pop().
- * (multi-provider/single-consumer scheme).
+ * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop
+ * and __cds_lfs_pop_all callers.
+ * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
+ * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
+ */
+extern struct cds_lfs_node *__cds_lfs_pop(cds_lfs_stack_ptr_t s);
+
+/*
+ * __cds_lfs_pop_all: pop all nodes from a stack.
+ *
+ * __cds_lfs_pop_all does not require any synchronization with other
+ * push, nor with other __cds_lfs_pop_all, but requires synchronization
+ * matching the technique used to synchronize __cds_lfs_pop:
+ *
+ * 1) If __cds_lfs_pop is called under rcu read lock critical section,
+ * both __cds_lfs_pop and cds_lfs_pop_all callers must wait for a
+ * grace period to pass before freeing the returned node or modifying
+ * the cds_lfs_node structure. However, no RCU read-side critical
+ * section is needed around __cds_lfs_pop_all.
+ * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop and
+ * __cds_lfs_pop_all callers.
+ * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
+ * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
*/
-extern struct cds_lfs_node *cds_lfs_pop(struct cds_lfs_stack *s);
+extern struct cds_lfs_head *__cds_lfs_pop_all(cds_lfs_stack_ptr_t s);
#endif /* !_LGPL_SOURCE */
+/*
+ * cds_lfs_for_each: Iterate over all nodes returned by
+ * __cds_lfs_pop_all.
+ * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
+ * @__node: node to use as iterator (struct cds_lfs_node pointer).
+ *
+ * Content written into each node before push is guaranteed to be
+ * consistent, but no other memory ordering is ensured.
+ */
+#define cds_lfs_for_each(__head, __node) \
+ for (__node = &__head->node; \
+ __node != NULL; \
+ __node = __node->next)
+
+/*
+ * cds_lfs_for_each_safe: Iterate over all nodes returned by
+ * __cds_lfs_pop_all, safe against node deletion.
+ * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
+ * @__node: node to use as iterator (struct cds_lfs_node pointer).
+ * @__n: struct cds_lfs_node pointer holding the next pointer (used
+ * internally).
+ *
+ * Content written into each node before push is guaranteed to be
+ * consistent, but no other memory ordering is ensured.
+ */
+#define cds_lfs_for_each_safe(__head, __node, __n) \
+ for (__node = &__head->node, __n = (__node ? __node->next : NULL); \
+ __node != NULL; \
+ __node = __n, __n = (__node ? __node->next : NULL))
+
#ifdef __cplusplus
}
#endif
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