X-Git-Url: http://plrg.eecs.uci.edu/git/?p=model-checker-benchmarks.git;a=blobdiff_plain;f=ms-queue%2Fmy_queue.c;h=dfdf819574e49bf4914f0b5b819390bf3236c1eb;hp=2377d01a4679cad3a4bdcc3175aa01bfed26ccec;hb=647601d3f341bb2a2a79534b3d044c039695839d;hpb=19711e157e116e61d9e302c54afa21797e7ddada

diff --git a/ms-queue/my_queue.c b/ms-queue/my_queue.c
index 2377d01..dfdf819 100644
--- a/ms-queue/my_queue.c
+++ b/ms-queue/my_queue.c
@@ -4,6 +4,10 @@
 
 #include "my_queue.h"
 
+#define relaxed memory_order_relaxed
+#define release memory_order_release
+#define acquire memory_order_acquire
+
 static unsigned int *node_nums;
 
 static unsigned int new_node()
@@ -57,34 +61,38 @@ void enqueue(queue_t *q, unsigned int val)
 	pointer next;
 	pointer tmp;
 
+	/* Get a fresh node, set its value field, then set it's next reference to null */
 	node = new_node();
 	store_32(&q->nodes[node].value, val);
-	tmp = atomic_load(&q->nodes[node].next);
+	tmp = atomic_load_explicit(&q->nodes[node].next, relaxed);
 	set_ptr(&tmp, 0); // NULL
-	atomic_store(&q->nodes[node].next, tmp);
+	atomic_store_explicit(&q->nodes[node].next, tmp, relaxed);
 
 	while (!success) {
-		tail = atomic_load(&q->tail);
-		next = atomic_load(&q->nodes[get_ptr(tail)].next);
-		if (tail == atomic_load(&q->tail)) {
+		//tail isn't actually synchronization point
+		tail = atomic_load_explicit(&q->tail, relaxed);
+		//acquire reference...
+		next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, memory_order_seq_cst);
+		if (tail == atomic_load_explicit(&q->tail, memory_order_seq_cst)) {
 			if (get_ptr(next) == 0) { // == NULL
 				pointer value = MAKE_POINTER(node, get_count(next) + 1);
-				success = atomic_compare_exchange_weak(&q->nodes[get_ptr(tail)].next,
-						&next, value);
+				success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
+						&next, value, memory_order_seq_cst, memory_order_seq_cst);
 			}
 			if (!success) {
-				unsigned int ptr = get_ptr(atomic_load(&q->nodes[get_ptr(tail)].next));
+				unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, memory_order_relaxed));
 				pointer value = MAKE_POINTER(ptr,
 						get_count(tail) + 1);
-				atomic_compare_exchange_strong(&q->tail,
-						&tail, value);
-				thrd_yield();
+				atomic_compare_exchange_strong_explicit(&q->tail,
+						&tail, value,
+						memory_order_seq_cst, memory_order_seq_cst);
 			}
 		}
 	}
-	atomic_compare_exchange_strong(&q->tail,
+	atomic_compare_exchange_strong_explicit(&q->tail,
 			&tail,
-			MAKE_POINTER(node, get_count(tail) + 1));
+			MAKE_POINTER(node, get_count(tail) + 1),
+			memory_order_seq_cst, memory_order_seq_cst);
 }
 
 unsigned int dequeue(queue_t *q)
@@ -96,25 +104,24 @@ unsigned int dequeue(queue_t *q)
 	pointer next;
 
 	while (!success) {
-		head = atomic_load(&q->head);
-		tail = atomic_load(&q->tail);
-		next = atomic_load(&q->nodes[get_ptr(head)].next);
-		if (atomic_load(&q->head) == head) {
+		head = atomic_load_explicit(&q->head, memory_order_seq_cst);
+		tail = atomic_load_explicit(&q->tail, memory_order_seq_cst);
+		next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, memory_order_seq_cst);
+		if (atomic_load_explicit(&q->head, memory_order_seq_cst) == head) {
 			if (get_ptr(head) == get_ptr(tail)) {
 				if (get_ptr(next) == 0) { // NULL
 					return 0; // NULL
 				}
-				atomic_compare_exchange_strong(&q->tail,
+				atomic_compare_exchange_strong_explicit(&q->tail,
 						&tail,
-						MAKE_POINTER(get_ptr(next), get_count(tail) + 1));
-				thrd_yield();
+						MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
+						memory_order_seq_cst, memory_order_seq_cst);
 			} else {
 				value = load_32(&q->nodes[get_ptr(next)].value);
-				success = atomic_compare_exchange_weak(&q->head,
+				success = atomic_compare_exchange_strong_explicit(&q->head,
 						&head,
-						MAKE_POINTER(get_ptr(next), get_count(head) + 1));
-				if (!success)
-					thrd_yield();
+						MAKE_POINTER(get_ptr(next), get_count(head) + 1),
+						memory_order_seq_cst, memory_order_seq_cst);
 			}
 		}
 	}