add treiber stack

[model-checker-benchmarks.git] / treiber-stack / my_stack.c

diff --git a/treiber-stack/my_stack.c b/treiber-stack/my_stack.c
new file mode 100644 (file)
index 0000000..5f3cc89
--- /dev/null
+++ b/treiber-stack/my_stack.c
@@ -0,0 +1,123 @@
+#include <threads.h>
+#include <stdlib.h>
+#include "librace.h"
+#include "model-assert.h"
+
+#include "my_stack.h"
+
+#define MAX_FREELIST 4 /* Each thread can own up to MAX_FREELIST free nodes */
+#define INITIAL_FREE 2 /* Each thread starts with INITIAL_FREE free nodes */
+
+#define POISON_IDX 0x666
+
+static unsigned int (*free_lists)[MAX_FREELIST];
+
+/* Search this thread's free list for a "new" node */
+static unsigned int new_node()
+{
+       int i;
+       int t = get_thread_num();
+       for (i = 0; i < MAX_FREELIST; i++) {
+               //unsigned int node = load_32(&free_lists[t][i]);
+               unsigned int node = free_lists[t][i];
+               if (node) {
+                       //store_32(&free_lists[t][i], 0);
+                       free_lists[t][i] = 0;
+                       return node;
+               }
+       }
+       /* free_list is empty? */
+       MODEL_ASSERT(0);
+       return 0;
+}
+
+/* Place this node index back on this thread's free list */
+static void reclaim(unsigned int node)
+{
+       int i;
+       int t = get_thread_num();
+
+       /* Don't reclaim NULL node */
+       //MODEL_ASSERT(node);
+
+       for (i = 0; i < MAX_FREELIST; i++) {
+               /* Should never race with our own thread here */
+               //unsigned int idx = load_32(&free_lists[t][i]);
+               unsigned int idx = free_lists[t][i];
+
+               /* Found empty spot in free list */
+               if (idx == 0) {
+                       //store_32(&free_lists[t][i], node);
+                       free_lists[t][i] = node;
+                       return;
+               }
+       }
+       /* free list is full? */
+       MODEL_ASSERT(0);
+}
+
+void init_stack(stack_t *s, int num_threads)
+{
+       int i, j;
+
+       /* Initialize each thread's free list with INITIAL_FREE pointers */
+       /* The actual nodes are initialized with poison indexes */
+       free_lists = malloc(num_threads * sizeof(*free_lists));
+       for (i = 0; i < num_threads; i++) {
+               for (j = 0; j < INITIAL_FREE; j++) {
+                       free_lists[i][j] = 1 + i * MAX_FREELIST + j;
+                       atomic_init(&s->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
+               }
+       }
+
+       /* initialize stack */
+       atomic_init(&s->top, MAKE_POINTER(0, 0));
+}
+
+void push(stack_t *s, unsigned int val) {
+       unsigned int nodeIdx = new_node();
+       node_t *node = &s->nodes[nodeIdx];
+       node->value = val;
+       pointer oldTop, newTop;
+       bool success;
+       while (true) {
+               // acquire
+               oldTop = atomic_load_explicit(&s->top, acquire);
+               newTop = MAKE_POINTER(nodeIdx, get_count(oldTop) + 1);
+               // relaxed
+               atomic_store_explicit(&node->next, oldTop, relaxed);
+
+               // release & relaxed
+               success = atomic_compare_exchange_strong_explicit(&s->top, &oldTop,
+                       newTop, release, relaxed);
+               if (success)
+                       break;
+       } 
+}
+
+unsigned int pop(stack_t *s) 
+{
+       pointer oldTop, newTop, next;
+       node_t *node;
+       bool success;
+       int val;
+       while (true) {
+               // acquire
+               oldTop = atomic_load_explicit(&s->top, acquire);
+               if (get_ptr(oldTop) == 0)
+                       return 0;
+               node = &s->nodes[get_ptr(oldTop)];
+               // relaxed
+               next = atomic_load_explicit(&node->next, relaxed);
+               newTop = MAKE_POINTER(get_ptr(next), get_count(oldTop) + 1);
+               // release & relaxed
+               success = atomic_compare_exchange_strong_explicit(&s->top, &oldTop,
+                       newTop, release, relaxed);
+               if (success)
+                       break;
+       }
+       val = node->value;
+       /* Reclaim the used slot */
+       reclaim(get_ptr(oldTop));
+       return val;
+}