X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=ms-queue%2Fmy_queue.c;h=ef3555296b1933cfb0f1b8d34d203de6089ea4d6;hb=ff4cd01eb602228cbd4091539c3f9754cb946dda;hp=1f8a4461e87e7688d1ca73c32b2b4503b1b0955b;hpb=7df8191c93d3664a3b1ea2dfcd0e88de2cfcc7c9;p=model-checker-benchmarks.git

diff --git a/ms-queue/my_queue.c b/ms-queue/my_queue.c
index 1f8a446..ef35552 100644
--- a/ms-queue/my_queue.c
+++ b/ms-queue/my_queue.c
@@ -1,130 +1,162 @@
-#include "main.h"
+#include <threads.h>
+#include <stdlib.h>
+#include "librace.h"
+#include "model-assert.h"
 
-extern unsigned pid;
-extern unsigned iterations;
-extern unsigned initial_nodes;
-extern private_t private;
-extern shared_mem_t* smp;
+#include "my_queue.h"
 
-void init_private()
-{
-	private.node = 2 + initial_nodes + pid;
-	private.value = 1 + initial_nodes + (pid * iterations);
+#define relaxed memory_order_relaxed
+#define release memory_order_release
+#define acquire memory_order_acquire
 
-}
+#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 */
 
-void init_memory()
-{
-}
+#define POISON_IDX 0x666
+
+static unsigned int (*free_lists)[MAX_FREELIST];
 
-static unsigned new_node()
+/* Search this thread's free list for a "new" node */
+static unsigned int new_node()
 {
-	return private.node;
+	int i;
+	int t = get_thread_num();
+	for (i = 0; i < MAX_FREELIST; i++) {
+		unsigned int node = load_32(&free_lists[t][i]);
+		if (node) {
+			store_32(&free_lists[t][i], 0);
+			return node;
+		}
+	}
+	/* free_list is empty? */
+	MODEL_ASSERT(0);
+	return 0;
 }
 
-static void reclaim(unsigned node)
+/* Place this node index back on this thread's free list */
+static void reclaim(unsigned int node)
 {
-	private.node = 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]);
+
+		/* Found empty spot in free list */
+		if (idx == 0) {
+			store_32(&free_lists[t][i], node);
+			return;
+		}
+	}
+	/* free list is full? */
+	MODEL_ASSERT(0);
 }
 
-void init_queue()
+void init_queue(queue_t *q, int num_threads)
 {
-	unsigned i;
+	int i, j;
 
-	/* initialize queue */
-	smp->head.sep.ptr = 1;
-	smp->head.sep.count = 0;
-	smp->tail.sep.ptr = 1;
-	smp->tail.sep.count = 0;
-	smp->nodes[1].next.sep.ptr = NULL;
-	smp->nodes[1].next.sep.count = 0;
-
-	/* initialize avail list */
-	for (i=2; i<MAX_NODES; i++) {
-		smp->nodes[i].next.sep.ptr = i+1;
-		smp->nodes[i].next.sep.count = 0;
-	}
-	smp->nodes[MAX_NODES].next.sep.ptr = NULL;
-	smp->nodes[MAX_NODES].next.sep.count = 0;
-
-	/* initialize queue contents */
-	if (initial_nodes > 0) {
-		for (i=2; i<initial_nodes+2; i++) {
-			smp->nodes[i].value = i;
-			smp->nodes[i-1].next.sep.ptr = i;
-			smp->nodes[i].next.sep.ptr = NULL;
+	/* 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] = 2 + i * MAX_FREELIST + j;
+			atomic_init(&q->nodes[free_lists[i][j]].next, MAKE_POINTER(POISON_IDX, 0));
 		}
-		smp->head.sep.ptr = 1;
-		smp->tail.sep.ptr = 1 + initial_nodes;    
 	}
+
+	/* initialize queue */
+	atomic_init(&q->head, MAKE_POINTER(1, 0));
+	atomic_init(&q->tail, MAKE_POINTER(1, 0));
+	atomic_init(&q->nodes[1].next, MAKE_POINTER(0, 0));
 }
 
-void enqueue(unsigned val)
+void enqueue(queue_t *q, unsigned int val)
 {
-	unsigned success;
-	unsigned node;
-	pointer_t tail;
-	pointer_t next;
+	int success = 0;
+	unsigned int node;
+	pointer tail;
+	pointer next;
+	pointer tmp;
 
 	node = new_node();
-	smp->nodes[node].value = val;
-	smp->nodes[node].next.sep.ptr = NULL;
-
-	for (success = FALSE; success == FALSE; ) {
-		tail.con = smp->tail.con;
-		next.con = smp->nodes[tail.sep.ptr].next.con;
-		if (tail.con == smp->tail.con) {
-			if (next.sep.ptr == NULL) {
-				success = cas(&smp->nodes[tail.sep.ptr].next, 
-						next.con,
-						MAKE_LONG(node, next.sep.count+1));
+	store_32(&q->nodes[node].value, val);
+	tmp = atomic_load_explicit(&q->nodes[node].next, relaxed);
+	set_ptr(&tmp, 0); // NULL
+	atomic_store_explicit(&q->nodes[node].next, tmp, relaxed);
+
+	while (!success) {
+		tail = atomic_load_explicit(&q->tail, acquire);
+		next = atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire);
+		if (tail == atomic_load_explicit(&q->tail, relaxed)) {
+
+			/* Check for uninitialized 'next' */
+			MODEL_ASSERT(get_ptr(next) != POISON_IDX);
+
+			if (get_ptr(next) == 0) { // == NULL
+				pointer value = MAKE_POINTER(node, get_count(next) + 1);
+				success = atomic_compare_exchange_strong_explicit(&q->nodes[get_ptr(tail)].next,
+						&next, value, release, release);
 			}
-			if (success == FALSE) {
-				cas(&smp->tail,
-						tail.con,
-						MAKE_LONG(smp->nodes[tail.sep.ptr].next.sep.ptr,
-							tail.sep.count+1));
+			if (!success) {
+				unsigned int ptr = get_ptr(atomic_load_explicit(&q->nodes[get_ptr(tail)].next, acquire));
+				pointer value = MAKE_POINTER(ptr,
+						get_count(tail) + 1);
+				atomic_compare_exchange_strong_explicit(&q->tail,
+						&tail, value,
+						release, release);
 				thrd_yield();
 			}
 		}
 	}
-	cas(&smp->tail, 
-			tail.con,
-			MAKE_LONG(node, tail.sep.count+1));
+	atomic_compare_exchange_strong_explicit(&q->tail,
+			&tail,
+			MAKE_POINTER(node, get_count(tail) + 1),
+			release, release);
 }
 
-unsigned dequeue()
+unsigned int dequeue(queue_t *q)
 {
-	unsigned value;
-	unsigned success;
-	pointer_t head;
-	pointer_t tail;
-	pointer_t next;
-
-	for (success = FALSE; success == FALSE; ) {
-		head.con = smp->head.con;
-		tail.con = smp->tail.con;
-		next.con = smp->nodes[head.sep.ptr].next.con;
-		if (smp->head.con == head.con) {
-			if (head.sep.ptr == tail.sep.ptr) {
-				if (next.sep.ptr == NULL) {
-					return NULL;
+	unsigned int value;
+	int success = 0;
+	pointer head;
+	pointer tail;
+	pointer next;
+
+	while (!success) {
+		head = atomic_load_explicit(&q->head, acquire);
+		tail = atomic_load_explicit(&q->tail, relaxed);
+		next = atomic_load_explicit(&q->nodes[get_ptr(head)].next, acquire);
+		if (atomic_load_explicit(&q->head, relaxed) == head) {
+			if (get_ptr(head) == get_ptr(tail)) {
+
+				/* Check for uninitialized 'next' */
+				MODEL_ASSERT(get_ptr(next) != POISON_IDX);
+
+				if (get_ptr(next) == 0) { // NULL
+					return 0; // NULL
 				}
-				cas(&smp->tail,
-						tail.con,
-						MAKE_LONG(next.sep.ptr, tail.sep.count+1));
+				atomic_compare_exchange_strong_explicit(&q->tail,
+						&tail,
+						MAKE_POINTER(get_ptr(next), get_count(tail) + 1),
+						release, release);
 				thrd_yield();
 			} else {
-				value = smp->nodes[next.sep.ptr].value;
-				success = cas(&smp->head,
-						head.con,
-						MAKE_LONG(next.sep.ptr, head.sep.count+1));
-				if (success == FALSE) {
+				value = load_32(&q->nodes[get_ptr(next)].value);
+				success = atomic_compare_exchange_strong_explicit(&q->head,
+						&head,
+						MAKE_POINTER(get_ptr(next), get_count(head) + 1),
+						release, release);
+				if (!success)
 					thrd_yield();
-				}
 			}
 		}
 	}
-	reclaim(head.sep.ptr);
+	reclaim(get_ptr(head));
 	return value;
 }