map_key_t key;
map_val_t val;
int top_level;
- uint64_t next[];
+ markable_t next[];
} node_t;
struct sl_iter {
const datatype_t *key_type;
};
+// Marking the <next> field of a node logically removes it from the list
+#if 0
+static inline markable_t MARK_NODE(node_t * x) { return TAG_VALUE((markable_t)x, TAG1); }
+static inline int HAS_MARK(markable_t x) { return (IS_TAGGED(x, TAG1) == TAG1); }
+static inline node_t * GET_NODE(markable_t x) { assert(!HAS_MARK(x)); return (node_t *)x; }
+static inline node_t * STRIP_MARK(markable_t x) { return ((node_t *)STRIP_TAG(x, TAG1)); }
+#else
+#define MARK_NODE(x) TAG_VALUE((markable_t)(x), TAG1)
+#define HAS_MARK(x) (IS_TAGGED((x), TAG1) == TAG1)
+#define GET_NODE(x) ((node_t *)(x))
+#define STRIP_MARK(x) ((node_t *)STRIP_TAG((x), TAG1))
+#endif
+
static int random_level (void) {
unsigned r = nbd_rand();
if (r & 1)
}
void sl_free (skiplist_t *sl) {
- node_t *item = (node_t *)(size_t)sl->head->next[0];
+ node_t *item = GET_NODE(sl->head->next[0]);
while (item) {
- node_t *next = (node_t *)(size_t)STRIP_TAG(item->next[0], TAG1);
+ node_t *next = STRIP_MARK(item->next[0]);
if (sl->key_type != NULL) {
- nbd_free((void *)(size_t)item->key);
+ nbd_free((void *)item->key);
}
nbd_free(item);
item = next;
}
}
-uint64_t sl_count (skiplist_t *sl) {
- uint64_t count = 0;
- node_t *item = (node_t *)(size_t)sl->head->next[0];
+size_t sl_count (skiplist_t *sl) {
+ size_t count = 0;
+ node_t *item = GET_NODE(sl->head->next[0]);
while (item) {
- if (!IS_TAGGED(item->next[0], TAG1)) {
+ if (!HAS_MARK(item->next[0])) {
count++;
}
- item = (node_t *)(size_t)STRIP_TAG(item->next[0], TAG1);
+ item = STRIP_MARK(item->next[0]);
}
return count;
}
// Traverse the levels of <sl> from the top level to the bottom
for (int level = start_level; level >= 0; --level) {
TRACE("s3", "find_preds: level %llu", level, 0);
- item = (node_t *)pred->next[level];
- if (EXPECT_FALSE(IS_TAGGED((uint64_t)item, TAG1))) {
- TRACE("s2", "find_preds: pred %p is marked for removal (item %p); retry", pred, item);
+ markable_t next = pred->next[level];
+ if (EXPECT_FALSE(HAS_MARK(next))) {
+ TRACE("s2", "find_preds: pred %p is marked for removal (next %p); retry", pred, next);
return find_preds(preds, succs, n, sl, key, help_remove); // retry
}
+ item = GET_NODE(next);
while (item != NULL) {
- uint64_t next = item->next[level];
+ next = item->next[level];
// A tag means an item is logically removed but not physically unlinked yet.
- while (EXPECT_FALSE(IS_TAGGED(next, TAG1))) {
+ while (EXPECT_FALSE(HAS_MARK(next))) {
// Skip over logically removed items.
if (!help_remove) {
- item = (node_t *)(size_t)STRIP_TAG(next, TAG1);
+ item = STRIP_MARK(next);
if (EXPECT_FALSE(item == NULL))
break;
next = item->next[level];
// Unlink logically removed items.
TRACE("s3", "find_preds: unlinking marked item %p; next is 0x%llx", item, next);
- uint64_t other = SYNC_CAS(&pred->next[level], (uint64_t)(size_t)item, STRIP_TAG(next, TAG1));
- if (other == (uint64_t)(size_t)item) {
- item = (node_t *)(size_t)STRIP_TAG(next, TAG1);
+ markable_t other = SYNC_CAS(&pred->next[level], item, STRIP_MARK(next));
+ if (other == (markable_t)item) {
+ item = STRIP_MARK(next);
next = (item != NULL) ? item->next[level] : DOES_NOT_EXIST;
TRACE("s3", "find_preds: now the current item is %p next is 0x%llx", item, next);
// The thread that completes the unlink should free the memory.
if (level == 0) {
+ node_t *unlinked = GET_NODE(other);
if (sl->key_type != NULL) {
- nbd_defer_free((void *)(size_t)((node_t *)(size_t)other)->key);
+ nbd_defer_free((void *)unlinked->key);
}
- nbd_defer_free(((node_t *)(size_t)other));
+ nbd_defer_free(unlinked);
}
} else {
TRACE("s3", "find_preds: lost race to unlink item %p from pred %p", item, pred);
TRACE("s3", "find_preds: pred's link changed to %p", other, 0);
- if (IS_TAGGED(other, TAG1))
+ if (HAS_MARK(other))
return find_preds(preds, succs, n, sl, key, help_remove); // retry
- item = (node_t *)(size_t)other;
+ item = GET_NODE(other);
next = (item != NULL) ? item->next[level] : DOES_NOT_EXIST;
}
}
break;
TRACE("s4", "find_preds: visiting item %p (next is %p)", item, next);
- TRACE("s4", "find_preds: key %p val %p", STRIP_TAG(item->key, TAG1), item->val);
+ TRACE("s4", "find_preds: key %p val %p", STRIP_MARK(item->key), item->val);
if (EXPECT_TRUE(sl->key_type == NULL)) {
- d = (uint64_t)item->key - (uint64_t)key;
+ d = item->key - key;
} else {
- d = sl->key_type->cmp((void *)(size_t)item->key, (void *)(size_t)key);
+ d = sl->key_type->cmp((void *)item->key, (void *)key);
}
if (d >= 0) {
}
pred = item;
- item = (node_t *)(size_t)next;
+ item = GET_NODE(next);
}
// The cast to unsigned is for the case when n is -1.
}
map_key_t sl_min_key (skiplist_t *sl) {
- node_t *item = (node_t *)(size_t)sl->head->next[0];
+ node_t *item = GET_NODE(sl->head->next[0]);
while (item != NULL) {
- uint64_t next = item->next[0];
- if (!IS_TAGGED(next, TAG1))
+ markable_t next = item->next[0];
+ if (!HAS_MARK(next))
return item->key;
- item = (node_t *)(size_t)STRIP_TAG(next, TAG1);
+ item = STRIP_MARK(next);
}
return DOES_NOT_EXIST;
}
// First insert <new_item> into the bottom level.
TRACE("s3", "sl_cas: attempting to insert item between %p and %p", preds[0], nexts[0]);
- map_key_t new_key = (sl->key_type == NULL)
- ? key
- : (map_key_t)(size_t)sl->key_type->clone((void *)(size_t)key);
+ map_key_t new_key = sl->key_type == NULL ? key : (map_key_t)sl->key_type->clone((void *)key);
new_item = node_alloc(n, new_key, new_val);
node_t *pred = preds[0];
- uint64_t next = new_item->next[0] = (uint64_t)(size_t)nexts[0];
+ markable_t next = new_item->next[0] = (markable_t)nexts[0];
for (int level = 1; level <= new_item->top_level; ++level) {
- new_item->next[level] = (uint64_t)(size_t)nexts[level];
+ new_item->next[level] = (markable_t)nexts[level];
}
- uint64_t other = SYNC_CAS(&pred->next[0], next, (uint64_t)(size_t)new_item);
+ markable_t other = SYNC_CAS(&pred->next[0], next, new_item);
if (other == next) {
TRACE("s3", "sl_cas: successfully inserted item %p at level 0", new_item, 0);
break; // success
}
TRACE("s3", "sl_cas: failed to change pred's link: expected %p found %p", next, other);
if (sl->key_type != NULL) {
- nbd_free((void *)(size_t)new_key);
+ nbd_free((void *)new_key);
}
nbd_free(new_item);
continue;
// Link <new_item> into <sl> from the bottom up.
for (int level = 1; level <= new_item->top_level; ++level) {
node_t *pred = preds[level];
- uint64_t next = (uint64_t)(size_t)nexts[level];
+ markable_t next = (markable_t)nexts[level];
do {
TRACE("s3", "sl_cas: attempting to insert item between %p and %p", pred, next);
- uint64_t other = SYNC_CAS(&pred->next[level], next, (uint64_t)(size_t)new_item);
+ markable_t other = SYNC_CAS(&pred->next[level], next, (markable_t)new_item);
if (other == next) {
TRACE("s3", "sl_cas: successfully inserted item %p at level %llu", new_item, level);
break; // success
TRACE("s3", "sl_cas: failed to change pred's link: expected %p found %p", next, other);
find_preds(preds, nexts, new_item->top_level, sl, key, TRUE);
pred = preds[level];
- next = (uint64_t)(size_t)nexts[level];
+ next = (markable_t)nexts[level];
// Update <new_item>'s next pointer
do {
// There in no need to continue linking in the item if another thread removed it.
- uint64_t old_next = ((volatile node_t *)new_item)->next[level];
- if (IS_TAGGED(old_next, TAG1))
+ markable_t old_next = ((volatile node_t *)new_item)->next[level];
+ if (HAS_MARK(old_next))
return DOES_NOT_EXIST; // success
// Use a CAS so we do not inadvertantly stomp on a mark another thread placed on the item.
// Mark and unlink <item> at each level of <sl> from the top down. If multiple threads try to concurrently remove
// the same item only one of them should succeed. Marking the bottom level establishes which of them succeeds.
for (int level = item->top_level; level > 0; --level) {
- uint64_t next;
- uint64_t old_next = item->next[level];
+ markable_t next;
+ markable_t old_next = item->next[level];
do {
next = old_next;
- old_next = SYNC_CAS(&item->next[level], next, TAG_VALUE(next, TAG1));
- if (IS_TAGGED(old_next, TAG1)) {
+ old_next = SYNC_CAS(&item->next[level], next, MARK_NODE((node_t *)next));
+ if (HAS_MARK(old_next)) {
TRACE("s2", "sl_remove: %p is already marked for removal by another thread at level %llu", item, level);
break;
}
} while (next != old_next);
node_t *pred = preds[level];
- TRACE("s2", "sl_remove: linking the item's pred %p to the item's successor %p", pred, STRIP_TAG(next, TAG1));
- uint64_t other = SYNC_CAS(&pred->next[level], (uint64_t)(size_t)item, STRIP_TAG(next, TAG1));
- if (other != (uint64_t)(size_t)item) {
+ TRACE("s2", "sl_remove: linking the item's pred %p to the item's successor %p", pred, STRIP_MARK(next));
+ markable_t other = SYNC_CAS(&pred->next[level], item, STRIP_MARK(next));
+ if (other != (markable_t)item) {
TRACE("s1", "sl_remove: unlink failed; pred's link changed from %p to %p", item, other);
// If our former predecessor now points past us we know another thread unlinked us. Otherwise, we need
// to search for a new set of preds.
continue; // <pred> points past <item> to the end of the list; go on to the next level.
int d = -1;
- if (!IS_TAGGED(other, TAG1)) {
- map_key_t other_key = ((node_t *)(size_t)other)->key;
+ if (!HAS_MARK(other)) {
+ map_key_t other_key = GET_NODE(other)->key;
if (EXPECT_TRUE(sl->key_type == NULL)) {
- d = (uint64_t)item->key - (uint64_t)other_key;
+ d = item->key - other_key;
} else {
- d = sl->key_type->cmp((void *)(size_t)item->key, (void *)(size_t)other_key);
+ d = sl->key_type->cmp((void *)item->key, (void *)other_key);
}
}
if (d > 0) {
}
}
- uint64_t next;
- uint64_t old_next = item->next[0];
+ markable_t next;
+ markable_t old_next = item->next[0];
do {
next = old_next;
- old_next = SYNC_CAS(&item->next[0], next, TAG_VALUE(next, TAG1));
- if (IS_TAGGED(old_next, TAG1)) {
+ old_next = SYNC_CAS(&item->next[0], next, MARK_NODE((node_t *)next));
+ if (HAS_MARK(old_next)) {
TRACE("s2", "sl_remove: %p is already marked for removal by another thread at level 0", item, 0);
return DOES_NOT_EXIST;
}
TRACE("s2", "sl_remove: replaced item %p's value with DOES_NOT_EXIT", item, 0);
node_t *pred = preds[0];
- TRACE("s2", "sl_remove: linking the item's pred %p to the item's successor %p", pred, STRIP_TAG(next, TAG1));
- if (SYNC_CAS(&pred->next[0], item, STRIP_TAG(next, TAG1))) {
+ TRACE("s2", "sl_remove: linking the item's pred %p to the item's successor %p", pred, STRIP_MARK(next));
+ if (SYNC_CAS(&pred->next[0], item, STRIP_MARK(next))) {
TRACE("s2", "sl_remove: unlinked item %p from the skiplist at level 0", item, 0);
// The thread that completes the unlink should free the memory.
if (sl->key_type != NULL) {
- nbd_defer_free((void *)(size_t)item->key);
+ nbd_defer_free((void *)item->key);
}
nbd_defer_free(item);
}
printf("(%d) ", level);
int i = 0;
while (item) {
- uint64_t next = item->next[level];
- printf("%s%p ", IS_TAGGED(next, TAG1) ? "*" : "", item);
- item = (node_t *)(size_t)STRIP_TAG(next, TAG1);
+ markable_t next = item->next[level];
+ printf("%s%p ", HAS_MARK(next) ? "*" : "", item);
+ item = STRIP_MARK(next);
if (i++ > 30) {
printf("...");
break;
node_t *item = sl->head;
int i = 0;
while (item) {
- int is_marked = IS_TAGGED(item->next[0], TAG1);
- printf("%s%p:0x%llx ", is_marked ? "*" : "", item, (uint64_t)(size_t)item->key);
+ int is_marked = HAS_MARK(item->next[0]);
+ printf("%s%p:0x%llx ", is_marked ? "*" : "", item, (map_key_t)item->key);
if (item != sl->head) {
printf("[%d]", item->top_level);
} else {
printf("[HEAD]");
}
for (int level = 1; level <= item->top_level; ++level) {
- node_t *next = (node_t *)(size_t)STRIP_TAG(item->next[level], TAG1);
- is_marked = IS_TAGGED(item->next[0], TAG1);
+ node_t *next = STRIP_MARK(item->next[level]);
+ is_marked = HAS_MARK(item->next[0]);
printf(" %p%s", next, is_marked ? "*" : "");
if (item == sl->head && item->next[level] == DOES_NOT_EXIST)
break;
}
printf("\n");
fflush(stdout);
- item = (node_t *)(size_t)STRIP_TAG(item->next[0], TAG1);
+ item = STRIP_MARK(item->next[0]);
if (i++ > 30) {
printf("...\n");
break;
map_val_t sl_iter_next (sl_iter_t *iter, map_key_t *key_ptr) {
assert(iter);
node_t *item = iter->next;
- while (item != NULL && IS_TAGGED(item->next[0], TAG1)) {
- item = (node_t *)(size_t)STRIP_TAG(item->next[0], TAG1);
+ while (item != NULL && HAS_MARK(item->next[0])) {
+ item = STRIP_MARK(item->next[0]);
}
if (item == NULL) {
iter->next = NULL;
return DOES_NOT_EXIST;
}
- iter->next = (node_t *)(size_t)STRIP_TAG(item->next[0], TAG1);
+ iter->next = STRIP_MARK(item->next[0]);
if (key_ptr != NULL) {
*key_ptr = item->key;
}
projects / nbds / blobdiff