// Setting MAX_LEVEL to 0 essentially makes this data structure the Harris-Michael lock-free list (in list.c).
#define MAX_LEVEL 31
-typedef struct sl_iter node_t;
-
-struct sl_iter {
+typedef struct node {
map_key_t key;
map_val_t val;
int top_level;
- node_t *next[];
+ uint64_t next[];
+} node_t;
+
+struct sl_iter {
+ node_t *next;
};
struct sl {
skiplist_t *sl_alloc (const datatype_t *key_type) {
skiplist_t *sl = (skiplist_t *)nbd_malloc(sizeof(skiplist_t));
sl->key_type = key_type;
- sl->head = node_alloc(MAX_LEVEL, NULL, 0);
+ sl->head = node_alloc(MAX_LEVEL, 0, 0);
memset(sl->head->next, 0, (MAX_LEVEL+1) * sizeof(skiplist_t *));
return sl;
}
void sl_free (skiplist_t *sl) {
- node_t *item = sl->head->next[0];
+ node_t *item = (node_t *)(size_t)sl->head->next[0];
while (item) {
- node_t *next = (node_t *)STRIP_TAG(item->next[0], TAG1);
+ node_t *next = (node_t *)(size_t)STRIP_TAG(item->next[0], TAG1);
+ if (sl->key_type != NULL) {
+ nbd_free((void *)(size_t)item->key);
+ }
nbd_free(item);
item = next;
}
uint64_t sl_count (skiplist_t *sl) {
uint64_t count = 0;
- node_t *item = sl->head->next[0];
+ node_t *item = (node_t *)(size_t)sl->head->next[0];
while (item) {
if (!IS_TAGGED(item->next[0], TAG1)) {
count++;
}
- item = (node_t *)STRIP_TAG(item->next[0], TAG1);
+ item = (node_t *)(size_t)STRIP_TAG(item->next[0], TAG1);
}
return count;
}
#if MAX_LEVEL > 2
// Optimization for small lists. No need to traverse empty higher levels.
start_level = 2;
- while (pred->next[start_level+1] != NULL) {
+ while (pred->next[start_level+1] != DOES_NOT_EXIST) {
start_level += start_level - 1;
if (EXPECT_FALSE(start_level >= MAX_LEVEL)) {
start_level = MAX_LEVEL;
// 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 = pred->next[level];
- if (EXPECT_FALSE(IS_TAGGED(item, TAG1))) {
- TRACE("s2", "find_preds: pred %p is marked for removal (item %p); retry", pred, item);
+ uint64_t next = pred->next[level];
+ if (EXPECT_FALSE(IS_TAGGED(next, TAG1))) {
+ 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
}
- while (item != NULL) {
- node_t *next = item->next[level];
+ while (next != DOES_NOT_EXIST) {
+ item = (node_t *)(size_t)next;
+ next = item->next[level];
// A tag means an item is logically removed but not physically unlinked yet.
while (EXPECT_FALSE(IS_TAGGED(next, TAG1))) {
// Skip over logically removed items.
if (!help_remove) {
- item = (node_t *)STRIP_TAG(item->next, TAG1);
+ item = (node_t *)(size_t)STRIP_TAG(next, TAG1);
if (EXPECT_FALSE(item == NULL))
break;
- TRACE("s3", "find_preds: skipping marked item %p (next is %p)", item, next);
next = item->next[level];
+ TRACE("s3", "find_preds: skipping marked item %p (next is 0x%llx)", item, next);
continue;
}
// Unlink logically removed items.
- node_t *other;
- TRACE("s3", "find_preds: unlinking marked item %p; next is %p", item, next);
- if ((other = SYNC_CAS(&pred->next[level], item, STRIP_TAG(next, TAG1))) == item) {
- item = (node_t *)STRIP_TAG(next, TAG1);
- if (EXPECT_FALSE(item == NULL))
- break;
- next = item->next[level];
- TRACE("s3", "find_preds: now the current item is %p next is %p", item, next);
+ 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);
+ 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) {
if (sl->key_type != NULL) {
- nbd_defer_free((void*)other->key);
+ nbd_defer_free((void *)(size_t)((node_t *)(size_t)other)->key);
}
- nbd_defer_free(other);
+ nbd_defer_free(((node_t *)(size_t)other));
}
} 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))
return find_preds(preds, succs, n, sl, key, help_remove); // retry
- item = other;
- if (EXPECT_FALSE(item == NULL))
- break;
- next = item->next[level];
+ item = (node_t *)(size_t)other;
+ next = (item != NULL) ? item->next[level] : DOES_NOT_EXIST;
}
}
if (EXPECT_TRUE(sl->key_type == NULL)) {
d = (uint64_t)item->key - (uint64_t)key;
} else {
- d = sl->key_type->cmp(item->key, key);
+ d = sl->key_type->cmp((void *)(size_t)item->key, (void *)(size_t)key);
}
if (d >= 0) {
}
pred = item;
- item = next;
+ item = (node_t *)(size_t)next;
}
// The cast to unsigned is for the case when n is -1.
// fill in empty levels
if (n == -1 && item != NULL) {
+ assert(item->top_level <= MAX_LEVEL);
for (int level = start_level + 1; level <= item->top_level; ++level) {
preds[level] = sl->head;
}
}
map_key_t sl_min_key (skiplist_t *sl) {
- node_t *item = sl->head->next[0];
+ node_t *item = (node_t *)(size_t)sl->head->next[0];
while (item != NULL) {
- node_t *next = item->next[0];
+ uint64_t next = item->next[0];
if (!IS_TAGGED(next, TAG1))
return item->key;
- item = (node_t *)STRIP_TAG(next, TAG1);
+ item = (node_t *)(size_t)STRIP_TAG(next, TAG1);
}
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 : sl->key_type->clone(key);
+ map_key_t new_key = (sl->key_type == NULL)
+ ? key
+ : (map_key_t)(size_t)sl->key_type->clone((void *)(size_t)key);
new_item = node_alloc(n, new_key, new_val);
node_t *pred = preds[0];
- node_t *next = new_item->next[0] = nexts[0];
+ uint64_t next = new_item->next[0] = (uint64_t)(size_t)nexts[0];
for (int level = 1; level <= new_item->top_level; ++level) {
- new_item->next[level] = nexts[level];
+ new_item->next[level] = (uint64_t)(size_t)nexts[level];
}
- node_t *other = SYNC_CAS(&pred->next[0], next, new_item);
+ uint64_t other = SYNC_CAS(&pred->next[0], next, (uint64_t)(size_t)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(new_key);
+ nbd_free((void *)(size_t)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];
- node_t *next = nexts[level];
+ uint64_t next = (uint64_t)(size_t)nexts[level];
do {
TRACE("s3", "sl_cas: attempting to insert item between %p and %p", pred, next);
- node_t *other = SYNC_CAS(&pred->next[level], next, new_item);
+ uint64_t other = SYNC_CAS(&pred->next[level], next, (uint64_t)(size_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 = nexts[level];
+ next = (uint64_t)(size_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.
- node_t *old_next = ((volatile node_t *)new_item)->next[level];
+ uint64_t old_next = ((volatile node_t *)new_item)->next[level];
if (IS_TAGGED(old_next, TAG1))
return DOES_NOT_EXIST; // success
// 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) {
- node_t *next;
- node_t *old_next = item->next[level];
+ uint64_t next;
+ uint64_t old_next = item->next[level];
do {
next = old_next;
old_next = SYNC_CAS(&item->next[level], next, TAG_VALUE(next, TAG1));
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));
- node_t *other = NULL;
- if ((other = SYNC_CAS(&pred->next[level], item, STRIP_TAG(next, TAG1))) != item) {
+ 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("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.
- if (other == NULL)
+ if (other == DOES_NOT_EXIST)
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 (EXPECT_TRUE(sl->key_type == NULL)) {
- d = (uint64_t)item->key - (uint64_t)other->key;
+ d = (uint64_t)item->key - (uint64_t)other_key;
} else {
- d = sl->key_type->cmp(item->key, other->key);
+ d = sl->key_type->cmp((void *)(size_t)item->key, (void *)(size_t)other_key);
}
}
if (d > 0) {
}
}
- node_t *next;
- node_t *old_next = item->next[0];
+ uint64_t next;
+ uint64_t old_next = item->next[0];
do {
next = old_next;
old_next = SYNC_CAS(&item->next[0], next, TAG_VALUE(next, TAG1));
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(item->key);
+ nbd_defer_free((void *)(size_t)item->key);
}
nbd_defer_free(item);
}
void sl_print (skiplist_t *sl) {
for (int level = MAX_LEVEL; level >= 0; --level) {
node_t *item = sl->head;
- if (item->next[level] == NULL)
+ if (item->next[level] == DOES_NOT_EXIST)
continue;
printf("(%d) ", level);
int i = 0;
while (item) {
- node_t *next = item->next[level];
+ uint64_t next = item->next[level];
printf("%s%p ", IS_TAGGED(next, TAG1) ? "*" : "", item);
- item = (node_t *)STRIP_TAG(next, TAG1);
+ item = (node_t *)(size_t)STRIP_TAG(next, TAG1);
if (i++ > 30) {
printf("...");
break;
int i = 0;
while (item) {
int is_marked = IS_TAGGED(item->next[0], TAG1);
- printf("%s%p:%p ", is_marked ? "*" : "", item, item->key);
+ printf("%s%p:0x%llx ", is_marked ? "*" : "", item, (uint64_t)(size_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 *)STRIP_TAG(item->next[level], TAG1);
+ node_t *next = (node_t *)(size_t)STRIP_TAG(item->next[level], TAG1);
is_marked = IS_TAGGED(item->next[0], TAG1);
printf(" %p%s", next, is_marked ? "*" : "");
- if (item == sl->head && item->next[level] == NULL)
+ if (item == sl->head && item->next[level] == DOES_NOT_EXIST)
break;
}
printf("\n");
fflush(stdout);
- item = (node_t *)STRIP_TAG(item->next[0], TAG1);
+ item = (node_t *)(size_t)STRIP_TAG(item->next[0], TAG1);
if (i++ > 30) {
printf("...\n");
break;
}
sl_iter_t *sl_iter_begin (skiplist_t *sl, map_key_t key) {
- node_t *iter = node_alloc(0, 0, 0);
- find_preds(NULL, &iter->next[0], 0, sl, key, FALSE);
+ sl_iter_t *iter = (sl_iter_t *)nbd_malloc(sizeof(sl_iter_t));
+ find_preds(NULL, &iter->next, 0, sl, key, FALSE);
return iter;
}
map_val_t sl_iter_next (sl_iter_t *iter, map_key_t *key_ptr) {
assert(iter);
- node_t *item = iter->next[0];
+ node_t *item = iter->next;
while (item != NULL && IS_TAGGED(item->next[0], TAG1)) {
- item = (node_t *)STRIP_TAG(item->next[0], TAG1);
+ item = (node_t *)(size_t)STRIP_TAG(item->next[0], TAG1);
}
if (item == NULL) {
- iter->next[0] = NULL;
+ iter->next = NULL;
return DOES_NOT_EXIST;
}
- iter->next[0] = item->next[0];
+ iter->next = (node_t *)(size_t)STRIP_TAG(item->next[0], TAG1);
if (key_ptr != NULL) {
*key_ptr = item->key;
}
projects / nbds / blobdiff