X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu%2Frculfqueue.h;h=f229cc77ca8d8a741a516dc4f3bbcae2cd67a90e;hp=f9b14fe93657343c5e1917ab77afcab4dc087a0d;hb=3d02c34dba0edc4a3554a3862a2ae96d77b3b4e8;hpb=453629a9317adef5b96c3d55e4dcd98db680997a

diff --git a/urcu/rculfqueue.h b/urcu/rculfqueue.h
index f9b14fe..f229cc7 100644
--- a/urcu/rculfqueue.h
+++ b/urcu/rculfqueue.h
@@ -1,3 +1,6 @@
+#ifndef _URCU_RCULFQUEUE_H
+#define _URCU_RCULFQUEUE_H
+
 /*
  * rculfqueue.h
  *
@@ -23,8 +26,8 @@
 #include <urcu/urcu_ref.h>
 #include <assert.h>
 
-#if (!defined(_GNU_SOURCE) && !defined(_LGPL_SOURCE))
-#error "Dynamic loader LGPL wrappers not implemented yet"
+#ifdef __cplusplus
+extern "C" {
 #endif
 
 /*
@@ -37,8 +40,6 @@
  * which point their reference count will be decremented.
  */
 
-#define URCU_LFQ_PERMANENT_REF		128
-
 struct rcu_lfq_node {
 	struct rcu_lfq_node *next;
 	struct urcu_ref ref;
@@ -49,88 +50,38 @@ struct rcu_lfq_queue {
 	struct rcu_lfq_node init;	/* Dummy initialization node */
 };
 
-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/rculfqueue-static.h>
 
-void rcu_lfq_enqueue(struct rcu_lfq_queue *q, struct rcu_lfq_node *node)
-{
-	urcu_ref_get(&node->ref);
+#define rcu_lfq_node_init	_rcu_lfq_node_init
+#define rcu_lfq_init		_rcu_lfq_init
+#define rcu_lfq_enqueue		_rcu_lfq_enqueue
+#define rcu_lfq_dequeue		_rcu_lfq_dequeue
 
-	/*
-	 * uatomic_cmpxchg() implicit memory barrier orders earlier stores to
-	 * node before publication.
-	 */
+#else /* !_LGPL_SOURCE */
 
-	rcu_read_lock();
-	for (;;) {
-		struct rcu_lfq_node *tail = rcu_dereference(q->tail);
-		struct rcu_lfq_node *next;
-
-		/*
-		 * Typically expect tail 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);
-			continue;
-		}
-	}
-}
+extern void rcu_lfq_node_init(struct rcu_lfq_node *node);
+extern void rcu_lfq_init(struct rcu_lfq_queue *q);
+extern void rcu_lfq_enqueue(struct rcu_lfq_queue *q, struct rcu_lfq_node *node);
 
 /*
  * 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 no be re-used before the
- * reference count reaches zero.
+ * grace period must be waited after execution of the release callback before
+ * performing the actual memory reclamation or modifying the rcu_lfq_node
+ * structure.
+ * In other words, 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).
  */
-struct rcu_lfq_node *
-rcu_lfq_dequeue(struct rcu_lfq_queue *q, void (*release)(struct urcu_ref *))
-{
-	rcu_read_lock();
-	for (;;) {
-		struct rcu_lfq_node *head = rcu_dereference(q->head);
-		struct rcu_lfq_node *next = rcu_dereference(head->next);
+extern struct rcu_lfq_node *
+rcu_lfq_dequeue(struct rcu_lfq_queue *q, void (*release)(struct urcu_ref *));
+
+#endif /* !_LGPL_SOURCE */
 
-		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 */
-				continue;
-			}
-		} else {
-			/* Empty */
-			rcu_read_unlock();
-			return NULL;
-		}
-	}
+#ifdef __cplusplus
 }
+#endif
+
+#endif /* _URCU_RCULFQUEUE_H */