X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu%2Frculfqueue.h;h=598fa5071a2ca727e43d07a67cb2a62eb4980632;hp=b712998c07a929cfa5d49da370bd0c676c72ecdb;hb=6a00c945d10d68e174c9fe96b2a98eb124b0d77e;hpb=c91b00b73226a431d5f7d8e262950fd3e83f40f1

diff --git a/urcu/rculfqueue.h b/urcu/rculfqueue.h
index b712998..598fa50 100644
--- a/urcu/rculfqueue.h
+++ b/urcu/rculfqueue.h
@@ -23,123 +23,69 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#include <urcu/urcu_ref.h>
 #include <assert.h>
+#include <urcu-call-rcu.h>
 
-#if (!defined(_GNU_SOURCE) && !defined(_LGPL_SOURCE))
-#error "Dynamic loader LGPL wrappers not implemented yet"
+#ifdef __cplusplus
+extern "C" {
 #endif
 
-/*
- * Lock-free RCU queue using reference counting. Enqueue and dequeue operations
- * hold a RCU read lock to deal with cmpxchg ABA problem. This implementation
- * keeps a dummy head node to ensure we can always update the queue locklessly.
- * Given that this is a queue, the dummy head node must always advance as we
- * dequeue entries. Therefore, we keep a reference count on each entry we are
- * dequeueing, so they can be kept as dummy head node until the next dequeue, at
- * which point their reference count will be decremented.
- */
-
-#define URCU_LFQ_PERMANENT_REF		128
+struct cds_lfq_queue_rcu;
 
-struct rcu_lfq_node {
-	struct rcu_lfq_node *next;
-	struct urcu_ref ref;
+struct cds_lfq_node_rcu {
+	struct cds_lfq_node_rcu *next;
+	int dummy;
 };
 
-struct rcu_lfq_queue {
-	struct rcu_lfq_node *head, *tail;
-	struct rcu_lfq_node init;	/* Dummy initialization node */
+struct cds_lfq_queue_rcu {
+	struct cds_lfq_node_rcu *head, *tail;
+	void (*queue_call_rcu)(struct rcu_head *head,
+		void (*func)(struct rcu_head *head));
 };
 
-void rcu_lfq_node_init(struct rcu_lfq_node *node)
-{
-	node->next = NULL;
-	urcu_ref_init(&node->ref);
-}
+#ifdef _LGPL_SOURCE
 
-void rcu_lfq_init(struct rcu_lfq_queue *q)
-{
-	rcu_lfq_node_init(&q->init);
-	/* Make sure the initial node is never freed. */
-	urcu_ref_set(&q->init.ref, URCU_LFQ_PERMANENT_REF);
-	q->head = q->tail = &q->init;
-}
+#include <urcu/static/rculfqueue.h>
 
-void rcu_lfq_enqueue(struct rcu_lfq_queue *q, struct rcu_lfq_node *node)
-{
-	urcu_ref_get(&node->ref);
-
-	/*
-	 * uatomic_cmpxchg() implicit memory barrier orders earlier stores to
-	 * node before publication.
-	 */
-
-	for (;;) {
-		struct rcu_lfq_node *tail, *next;
-
-		rcu_read_lock();
-		tail = rcu_dereference(q->tail);
-		/*
-		 * Typically expect tail->next to be NULL.
-		 */
-		next = uatomic_cmpxchg(&tail->next, NULL, node);
-		if (next == NULL) {
-			/*
-			 * Tail was at the end of queue, we successfully
-			 * appended to it.
-			 * Now move tail (another enqueue might beat
-			 * us to it, that's fine).
-			 */
-			uatomic_cmpxchg(&q->tail, tail, node);
-			rcu_read_unlock();
-			return;
-		} else {
-			/*
-			 * Failure to append to current tail. Help moving tail
-			 * further and retry.
-			 */
-			uatomic_cmpxchg(&q->tail, tail, next);
-			rcu_read_unlock();
-			continue;
-		}
-	}
-}
+#define cds_lfq_node_init_rcu		_cds_lfq_node_init_rcu
+#define cds_lfq_init_rcu		_cds_lfq_init_rcu
+#define cds_lfq_destroy_rcu		_cds_lfq_destroy_rcu
+#define cds_lfq_enqueue_rcu		_cds_lfq_enqueue_rcu
+#define cds_lfq_dequeue_rcu		_cds_lfq_dequeue_rcu
+
+#else /* !_LGPL_SOURCE */
+
+extern void cds_lfq_node_init_rcu(struct cds_lfq_node_rcu *node);
+extern void cds_lfq_init_rcu(struct cds_lfq_queue_rcu *q,
+			     void queue_call_rcu(struct rcu_head *head,
+					void (*func)(struct rcu_head *head)));
+/*
+ * The queue should be emptied before calling destroy.
+ *
+ * Return 0 on success, -EPERM if queue is not empty.
+ */
+extern int cds_lfq_destroy_rcu(struct cds_lfq_queue_rcu *q);
 
 /*
- * The entry returned by dequeue must be taken care of by doing a urcu_ref_put,
- * which calls the release primitive when the reference count drops to zero. A
- * grace period must be waited before performing the actual memory reclamation
- * in the release primitive.
- * The entry lfq node returned by dequeue must not be modified/re-used/freed
- * until the reference count reaches zero and a grace period has elapsed (after
- * the refcount reached 0).
+ * Should be called under rcu read lock critical section.
  */
-struct rcu_lfq_node *
-rcu_lfq_dequeue(struct rcu_lfq_queue *q, void (*release)(struct urcu_ref *))
-{
-	for (;;) {
-		struct rcu_lfq_node *head, *next;
-
-		rcu_read_lock();
-		head = rcu_dereference(q->head);
-		next = rcu_dereference(head->next);
-		if (next) {
-			if (uatomic_cmpxchg(&q->head, head, next) == head) {
-				rcu_read_unlock();
-				urcu_ref_put(&head->ref, release);
-				return next;
-			} else {
-				/* Concurrently pushed, retry */
-				rcu_read_unlock();
-				continue;
-			}
-		} else {
-			/* Empty */
-			rcu_read_unlock();
-			return NULL;
-		}
-	}
+extern void cds_lfq_enqueue_rcu(struct cds_lfq_queue_rcu *q,
+				struct cds_lfq_node_rcu *node);
+
+/*
+ * Should be called 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_lfq_node_rcu structure.
+ * Returns NULL if queue is empty.
+ */
+extern
+struct cds_lfq_node_rcu *cds_lfq_dequeue_rcu(struct cds_lfq_queue_rcu *q);
+
+#endif /* !_LGPL_SOURCE */
+
+#ifdef __cplusplus
 }
+#endif
 
 #endif /* _URCU_RCULFQUEUE_H */