#include "mem.h"
typedef struct node {
- map_key_t key;
- map_val_t val;
- uint64_t next; // next node
+ map_key_t key;
+ map_val_t val;
+ markable_t next; // next node
} node_t;
struct ll_iter {
const datatype_t *key_type;
};
+// Marking the <next> field of a node logically removes it from the list
+#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))
+
static node_t *node_alloc (map_key_t key, map_val_t val) {
node_t *item = (node_t *)nbd_malloc(sizeof(node_t));
item->key = key;
}
void ll_free (list_t *ll) {
- node_t *item = (node_t *)(size_t)ll->head->next; // the head can't be tagged
- while (item) {
- node_t *next = (node_t *)(size_t)STRIP_TAG(item->next, TAG1);
+ node_t *item = STRIP_MARK(ll->head->next);
+ while (item != NULL) {
+ node_t *next = STRIP_MARK(item->next);
nbd_free(item);
item = next;
}
}
-uint64_t ll_count (list_t *ll) {
- uint64_t count = 0;
- node_t *item = (node_t *)(size_t)ll->head->next;
+size_t ll_count (list_t *ll) {
+ size_t count = 0;
+ node_t *item = STRIP_MARK(ll->head->next);
while (item) {
- if (!IS_TAGGED(item->next, TAG1)) {
+ if (!HAS_MARK(item->next)) {
count++;
}
- item = (node_t *)(size_t)STRIP_TAG(item->next, TAG1);
+ item = STRIP_MARK(item->next);
}
return count;
}
static int find_pred (node_t **pred_ptr, node_t **item_ptr, list_t *ll, map_key_t key, int help_remove) {
node_t *pred = ll->head;
- node_t *item = (node_t *)(size_t)pred->next;
+ node_t *item = GET_NODE(pred->next);
TRACE("l2", "find_pred: searching for key %p in list (head is %p)", key, pred);
while (item != NULL) {
- uint64_t next = item->next;
+ markable_t next = item->next;
- // A tag means an item is logically removed but not physically unlinked yet.
- while (EXPECT_FALSE(IS_TAGGED(next, TAG1))) {
+ // A mark means the node is logically removed but not physically unlinked yet.
+ while (EXPECT_FALSE(HAS_MARK(next))) {
// Skip over logically removed items.
if (!help_remove) {
- item = (node_t *)(size_t)STRIP_TAG(item->next, TAG1);
+ item = STRIP_MARK(item->next);
if (EXPECT_FALSE(item == NULL))
break;
TRACE("l3", "find_pred: skipping marked item %p (next is %p)", item, next);
// Unlink logically removed items.
TRACE("l3", "find_pred: unlinking marked item %p next is %p", item, next);
- uint64_t other = SYNC_CAS(&pred->next, (uint64_t)(size_t)item, STRIP_TAG(next, TAG1));
- if (other == (uint64_t)(size_t)item) {
+ markable_t other = SYNC_CAS(&pred->next, item, STRIP_MARK(next));
+ if (other == (markable_t)item) {
TRACE("l2", "find_pred: unlinked item %p from pred %p", item, pred);
- item = (node_t *)(size_t)STRIP_TAG(next, TAG1);
+ item = STRIP_MARK(next);
next = (item != NULL) ? item->next : DOES_NOT_EXIST;
TRACE("l3", "find_pred: now current item is %p next is %p", item, next);
// The thread that completes the unlink should free the memory.
+ node_t *unlinked = GET_NODE(other);
if (ll->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("l2", "find_pred: lost a race to unlink item %p from pred %p", item, pred);
TRACE("l2", "find_pred: pred's link changed to %p", other, 0);
- if (IS_TAGGED(other, TAG1))
+ if (HAS_MARK(other))
return find_pred(pred_ptr, item_ptr, ll, key, help_remove); // retry
- item = (node_t *)(size_t)other;
+ item = GET_NODE(other);
next = (item != NULL) ? item->next : DOES_NOT_EXIST;
}
}
int d;
if (EXPECT_TRUE(ll->key_type == NULL)) {
- d = (uint64_t)item->key - (uint64_t)key;
+ d = item->key - key;
} else {
- d = ll->key_type->cmp((void *)(size_t)item->key, (void *)(size_t)key);
+ d = ll->key_type->cmp((void *)item->key, (void *)key);
}
- if (next != DOES_NOT_EXIST && ((node_t *)next)->key < item->key) {
+ if (next != DOES_NOT_EXIST && GET_NODE(next)->key < item->key) {
lwt_halt();
assert(0);
}
}
pred = item;
- item = (node_t *)(size_t)next;
+ item = GET_NODE(next);
}
// <key> is not in <ll>.
// Create a new item and insert it into the list.
TRACE("l2", "ll_cas: attempting to insert item between %p and %p", pred, pred->next);
- map_key_t new_key = (ll->key_type == NULL)
- ? key
- : (map_key_t)(size_t)ll->key_type->clone((void *)(size_t)key);
+ map_key_t new_key = ll->key_type == NULL ? key : (map_key_t)ll->key_type->clone((void *)key);
node_t *new_item = node_alloc(new_key, new_val);
- uint64_t next = new_item->next = (uint64_t)(size_t)old_item;
- uint64_t other = SYNC_CAS(&pred->next, next, new_item);
+ markable_t next = new_item->next = (markable_t)old_item;
+ markable_t other = SYNC_CAS(&pred->next, next, new_item);
if (other == next) {
TRACE("l1", "ll_cas: successfully inserted new item %p", new_item, 0);
return DOES_NOT_EXIST; // success
// Lost a race. Failed to insert the new item into the list.
TRACE("l1", "ll_cas: lost a race. CAS failed. expected pred's link to be %p but found %p", next, other);
if (ll->key_type != NULL) {
- nbd_free((void *)(size_t)new_key);
+ nbd_free((void *)new_key);
}
nbd_free(new_item);
continue; // retry
}
// Mark <item> removed. If multiple threads try to remove the same item only one of them should succeed.
- uint64_t next;
- uint64_t old_next = item->next;
+ markable_t next;
+ markable_t old_next = item->next;
do {
next = old_next;
- old_next = SYNC_CAS(&item->next, next, TAG_VALUE(next, TAG1));
- if (IS_TAGGED(old_next, TAG1)) {
+ old_next = SYNC_CAS(&item->next, next, MARK_NODE(STRIP_MARK(next)));
+ if (HAS_MARK(old_next)) {
TRACE("l1", "ll_remove: lost a race -- %p is already marked for removal by another thread", item, 0);
return DOES_NOT_EXIST;
}
} while (next != old_next);
TRACE("l2", "ll_remove: logically removed item %p", item, 0);
- ASSERT(IS_TAGGED(((volatile node_t *)item)->next, TAG1));
+ ASSERT(HAS_MARK(((volatile node_t *)item)->next));
// Atomically swap out the item's value in case another thread is updating the item while we are
// removing it. This establishes which operation occurs first logically, the update or the remove.
// item logically removed for a later call (or some other thread) to physically unlink. By marking the
// item earlier, we logically removed it.
TRACE("l2", "ll_remove: unlink the item by linking its pred %p to its successor %p", pred, next);
- uint64_t other;
- if ((other = SYNC_CAS(&pred->next, (uint64_t)(size_t)item, next)) != (uint64_t)(size_t)item) {
+ markable_t other;
+ if ((other = SYNC_CAS(&pred->next, item, next)) != (markable_t)item) {
TRACE("l1", "ll_remove: unlink failed; pred's link changed from %p to %p", item, other);
return val;
}
// The thread that completes the unlink should free the memory.
if (ll->key_type != NULL) {
- nbd_defer_free((void *)(size_t)item->key);
+ nbd_defer_free((void *)item->key);
}
nbd_defer_free(item);
TRACE("l1", "ll_remove: successfully unlinked item %p from the list", item, 0);
}
void ll_print (list_t *ll) {
- uint64_t next = ll->head->next;
+ markable_t next = ll->head->next;
int i = 0;
while (next != DOES_NOT_EXIST) {
- if (IS_TAGGED(next, TAG1)) {
+ if (HAS_MARK(next)) {
printf("*");
}
- node_t *item = (node_t *)(size_t)STRIP_TAG(next, TAG1);
+ node_t *item = STRIP_MARK(next);
if (item == NULL)
break;
printf("%p:0x%llx ", item, item->key);
map_val_t ll_iter_next (ll_iter_t *iter, map_key_t *key_ptr) {
assert(iter);
node_t *item = iter->next;
- while (item != NULL && IS_TAGGED(item->next, TAG1)) {
- item = (node_t *)(size_t)STRIP_TAG(item->next, TAG1);
+ while (item != NULL && HAS_MARK(item->next)) {
+ item = STRIP_MARK(item->next);
}
if (item == NULL) {
iter->next = NULL;
return DOES_NOT_EXIST;
}
- iter->next = (node_t *)(size_t)STRIP_TAG(item->next, TAG1);
+ iter->next = STRIP_MARK(item->next);
if (key_ptr != NULL) {
*key_ptr = item->key;
}
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