LGPL-ize wfqueue

[urcu.git] / urcu / wfqueue.h

diff --git a/urcu/wfqueue.h b/urcu/wfqueue.h
index 2eaace1c260f99e7562a36649fc5129fdb03cce0..3d32b05c580c4634fd98a373cf86514228d3adba 100644 (file)
--- a/urcu/wfqueue.h
+++ b/urcu/wfqueue.h
@@ -31,13 +31,6 @@
 extern "C" {
 #endif
 
-#if (!defined(_GNU_SOURCE) && !defined(_LGPL_SOURCE))
-#error "Dynamic loader LGPL wrappers not implemented yet"
-#endif
-
-#define WFQ_ADAPT_ATTEMPTS             10      /* Retry if being set */
-#define WFQ_WAIT                       10      /* Wait 10 ms if being set */
-
 /*
  * Queue with wait-free enqueue/blocking dequeue.
  * This implementation adds a dummy head node when the queue is empty to ensure
@@ -57,100 +50,23 @@ struct wfq_queue {
        pthread_mutex_t lock;
 };
 
-void wfq_node_init(struct wfq_node *node)
-{
-       node->next = NULL;
-}
+#ifdef _LGPL_SOURCE
 
-void wfq_init(struct wfq_queue *q)
-{
-       int ret;
+#include <urcu/wfqueue-static.h>
 
-       wfq_node_init(&q->dummy);
-       /* Set queue head and tail */
-       q->head = &q->dummy;
-       q->tail = &q->dummy.next;
-       ret = pthread_mutex_init(&q->lock, NULL);
-       assert(!ret);
-}
+#define wfq_node_init          _wfq_node_init
+#define wfq_init               _wfq_init
+#define wfq_enqueue            _wfq_enqueue
+#define wfq_dequeue_blocking   _wfq_dequeue_blocking
 
-void wfq_enqueue(struct wfq_queue *q, struct wfq_node *node)
-{
-       struct wfq_node **old_tail;
+#else /* !_LGPL_SOURCE */
 
-       /*
-        * uatomic_xchg() implicit memory barrier orders earlier stores to data
-        * structure containing node and setting node->next to NULL before
-        * publication.
-        */
-       old_tail = uatomic_xchg(&q->tail, node);
-       /*
-        * At this point, dequeuers see a NULL old_tail->next, which indicates
-        * that the queue is being appended to. The following store will append
-        * "node" to the queue from a dequeuer perspective.
-        */
-       STORE_SHARED(*old_tail, node);
-}
+extern void wfq_node_init(struct wfq_node *node);
+extern void wfq_init(struct wfq_queue *q);
+extern void wfq_enqueue(struct wfq_queue *q, struct wfq_node *node);
+extern struct wfq_node *wfq_dequeue_blocking(struct wfq_queue *q);
 
-/*
- * It is valid to reuse and free a dequeued node immediately.
- *
- * No need to go on a waitqueue here, as there is no possible state in which the
- * list could cause dequeue to busy-loop needlessly while waiting for another
- * thread to be scheduled. The queue appears empty until tail->next is set by
- * enqueue.
- */
-struct wfq_node *
-__wfq_dequeue_blocking(struct wfq_queue *q)
-{
-       struct wfq_node *node, *next;
-       int attempt = 0;
-
-       /*
-        * Queue is empty if it only contains the dummy node.
-        */
-       if (q->head == &q->dummy && LOAD_SHARED(q->tail) == &q->dummy.next)
-               return NULL;
-       node = q->head;
-
-       /*
-        * Adaptative busy-looping waiting for enqueuer to complete enqueue.
-        */
-       while ((next = LOAD_SHARED(node->next)) == NULL) {
-               if (++attempt >= WFQ_ADAPT_ATTEMPTS) {
-                       poll(NULL, 0, WFQ_WAIT);        /* Wait for 10ms */
-                       attempt = 0;
-               } else
-                       cpu_relax();
-       }
-       /*
-        * Move queue head forward.
-        */
-       q->head = next;
-       /*
-        * Requeue dummy node if we just dequeued it.
-        */
-       if (node == &q->dummy) {
-               wfq_node_init(node);
-               wfq_enqueue(q, node);
-               return __wfq_dequeue_blocking(q);
-       }
-       return node;
-}
-
-struct wfq_node *
-wfq_dequeue_blocking(struct wfq_queue *q)
-{
-       struct wfq_node *retnode;
-       int ret;
-
-       ret = pthread_mutex_lock(&q->lock);
-       assert(!ret);
-       retnode = __wfq_dequeue_blocking(q);
-       ret = pthread_mutex_unlock(&q->lock);
-       assert(!ret);
-       return retnode;
-}
+#endif /* !_LGPL_SOURCE */
 
 #ifdef __cplusplus
 }