X-Git-Url: https://pd.if.org/git/?p=nbds;a=blobdiff_plain;f=map%2Fskiplist.c;h=afdb1f72393cba01d5849dbad735f9087c2945fc;hp=49ef21b3d32bcfe43c0e38cfdad883be1994eda5;hb=a19bce63ef088ad03004bc8e9bfde4901d978151;hpb=f7a1c10d18dcc2654d0c9b1f5ffc9f4ec9b23776

diff --git a/map/skiplist.c b/map/skiplist.c
index 49ef21b..afdb1f7 100644
--- a/map/skiplist.c
+++ b/map/skiplist.c
@@ -28,12 +28,14 @@
 // 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 node {
-    void *key;
-    uint64_t val;
+typedef struct sl_iter node_t;
+
+struct sl_iter {
+    map_key_t key;
+    map_val_t val;
     int top_level;
-    struct node *next[];
-} node_t;
+    node_t *next[];
+};
 
 struct sl {
     node_t *head;
@@ -52,7 +54,7 @@ static int random_level (void) {
     return n;
 }
 
-static node_t *node_alloc (int level, void *key, uint64_t val) {
+static node_t *node_alloc (int level, map_key_t key, map_val_t val) {
     assert(level >= 0 && level <= MAX_LEVEL);
     size_t sz = sizeof(node_t) + (level + 1) * sizeof(node_t *);
     node_t *item = (node_t *)nbd_malloc(sz);
@@ -74,7 +76,7 @@ skiplist_t *sl_alloc (const datatype_t *key_type) {
 void sl_free (skiplist_t *sl) {
     node_t *item = sl->head->next[0];
     while (item) {
-        node_t *next = (node_t *)STRIP_TAG(item->next[0]);
+        node_t *next = (node_t *)STRIP_TAG(item->next[0], TAG1);
         nbd_free(item);
         item = next;
     }
@@ -84,15 +86,15 @@ uint64_t sl_count (skiplist_t *sl) {
     uint64_t count = 0;
     node_t *item = sl->head->next[0];
     while (item) {
-        if (!IS_TAGGED(item->next[0])) {
+        if (!IS_TAGGED(item->next[0], TAG1)) {
             count++;
         }
-        item = (node_t *)STRIP_TAG(item->next[0]);
+        item = (node_t *)STRIP_TAG(item->next[0], TAG1);
     }
     return count;
 }
 
-static node_t *find_preds (node_t **preds, node_t **succs, int n, skiplist_t *sl, void *key, int help_remove) {
+static node_t *find_preds (node_t **preds, node_t **succs, int n, skiplist_t *sl, map_key_t key, int help_remove) {
     node_t *pred = sl->head;
     node_t *item = NULL;
     TRACE("s2", "find_preds: searching for key %p in skiplist (head is %p)", key, pred);
@@ -117,7 +119,7 @@ static node_t *find_preds (node_t **preds, node_t **succs, int n, skiplist_t *sl
     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))) {
+        if (EXPECT_FALSE(IS_TAGGED(item, TAG1))) {
             TRACE("s2", "find_preds: pred %p is marked for removal (item %p); retry", pred, item);
             return find_preds(preds, succs, n, sl, key, help_remove); // retry
         }
@@ -125,11 +127,11 @@ static node_t *find_preds (node_t **preds, node_t **succs, int n, skiplist_t *sl
             node_t *next = item->next[level];
 
             // A tag means an item is logically removed but not physically unlinked yet.
-            while (EXPECT_FALSE(IS_TAGGED(next))) {
+            while (EXPECT_FALSE(IS_TAGGED(next, TAG1))) {
 
                 // Skip over logically removed items.
                 if (!help_remove) {
-                    item = (node_t *)STRIP_TAG(item->next);
+                    item = (node_t *)STRIP_TAG(item->next, TAG1);
                     if (EXPECT_FALSE(item == NULL))
                         break;
                     TRACE("s3", "find_preds: skipping marked item %p (next is %p)", item, next);
@@ -140,8 +142,8 @@ static node_t *find_preds (node_t **preds, node_t **succs, int n, skiplist_t *sl
                 // 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))) == item) {
-                    item = (node_t *)STRIP_TAG(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];
@@ -157,7 +159,7 @@ static node_t *find_preds (node_t **preds, node_t **succs, int n, skiplist_t *sl
                 } 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))
+                    if (IS_TAGGED(other, TAG1))
                         return find_preds(preds, succs, n, sl, key, help_remove); // retry
                     item = other;
                     if (EXPECT_FALSE(item == NULL))
@@ -170,7 +172,7 @@ static node_t *find_preds (node_t **preds, node_t **succs, int n, skiplist_t *sl
                 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), item->val);
+            TRACE("s4", "find_preds: key %p val %p", STRIP_TAG(item->key, TAG1), item->val);
 
             if (EXPECT_TRUE(sl->key_type == NULL)) {
                 d = (uint64_t)item->key - (uint64_t)key;
@@ -214,13 +216,13 @@ static node_t *find_preds (node_t **preds, node_t **succs, int n, skiplist_t *sl
 }
 
 // Fast find that does not help unlink partially removed nodes and does not return the node's predecessors.
-uint64_t sl_lookup (skiplist_t *sl, void *key) {
+map_val_t sl_lookup (skiplist_t *sl, map_key_t key) {
     TRACE("s1", "sl_lookup: searching for key %p in skiplist %p", key, sl);
     node_t *item = find_preds(NULL, NULL, 0, sl, key, FALSE);
 
     // If we found an <item> matching the <key> return its value.
     if (item != NULL) {
-        uint64_t val = item->val;
+        map_val_t val = item->val;
         if (val != DOES_NOT_EXIST) {
             TRACE("s1", "sl_lookup: found item %p. val %p. returning item", item, item->val);
             return val;
@@ -231,18 +233,18 @@ uint64_t sl_lookup (skiplist_t *sl, void *key) {
     return DOES_NOT_EXIST;
 }
 
-void *sl_min_key (skiplist_t *sl) {
+map_key_t sl_min_key (skiplist_t *sl) {
     node_t *item = sl->head->next[0];
     while (item != NULL) {
         node_t *next = item->next[0];
-        if (!IS_TAGGED(next))
+        if (!IS_TAGGED(next, TAG1))
             return item->key;
-        item = (node_t *)STRIP_TAG(next);
+        item = (node_t *)STRIP_TAG(next, TAG1);
     }
     return DOES_NOT_EXIST;
 }
 
-uint64_t sl_cas (skiplist_t *sl, void *key, uint64_t expectation, uint64_t new_val) {
+map_val_t sl_cas (skiplist_t *sl, map_key_t key, map_val_t expectation, map_val_t new_val) {
     TRACE("s1", "sl_cas: key %p skiplist %p", key, sl);
     TRACE("s1", "sl_cas: expectation %p new value %p", expectation, new_val);
     ASSERT((int64_t)new_val > 0);
@@ -265,7 +267,7 @@ uint64_t sl_cas (skiplist_t *sl, void *key, uint64_t expectation, uint64_t new_v
 
             // First insert <new_item> into the bottom level.
             TRACE("s3", "sl_cas: attempting to insert item between %p and %p", preds[0], nexts[0]);
-            void *new_key  = (sl->key_type == NULL) ? key : sl->key_type->clone(key);
+            map_key_t new_key  = (sl->key_type == NULL) ? key : sl->key_type->clone(key);
             new_item = node_alloc(n, new_key, new_val);
             node_t *pred = preds[0];
             node_t *next = new_item->next[0] = nexts[0];
@@ -286,7 +288,7 @@ uint64_t sl_cas (skiplist_t *sl, void *key, uint64_t expectation, uint64_t new_v
         }
 
         // Found an item in the skiplist that matches the key.
-        uint64_t old_item_val = old_item->val;
+        map_val_t old_item_val = old_item->val;
         do {
             // If the item's value is DOES_NOT_EXIST it means another thread removed the node out from under us.
             if (EXPECT_FALSE(old_item_val == DOES_NOT_EXIST)) {
@@ -304,7 +306,7 @@ uint64_t sl_cas (skiplist_t *sl, void *key, uint64_t expectation, uint64_t new_v
             // replace DOES_NOT_EXIST with our value. Then another thread that is updating the value could think it
             // succeeded and return our value even though we indicated that the node has been removed. If the CAS 
             // fails it means another thread either removed the node or updated its value.
-            uint64_t ret_val = SYNC_CAS(&old_item->val, old_item_val, new_val);
+            map_val_t ret_val = SYNC_CAS(&old_item->val, old_item_val, new_val);
             if (ret_val == old_item_val) {
                 TRACE("s1", "sl_cas: the CAS succeeded. updated the value of the item", 0, 0);
                 return ret_val; // success
@@ -335,7 +337,7 @@ uint64_t sl_cas (skiplist_t *sl, void *key, uint64_t expectation, uint64_t new_v
             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];
-                if (IS_TAGGED(old_next))
+                if (IS_TAGGED(old_next, TAG1))
                     return DOES_NOT_EXIST; // success
 
                 // Use a CAS so we do not inadvertantly stomp on a mark another thread placed on the item.
@@ -347,7 +349,7 @@ uint64_t sl_cas (skiplist_t *sl, void *key, uint64_t expectation, uint64_t new_v
     return DOES_NOT_EXIST; // success
 }
 
-uint64_t sl_remove (skiplist_t *sl, void *key) {
+map_val_t sl_remove (skiplist_t *sl, map_key_t key) {
     TRACE("s1", "sl_remove: removing item with key %p from skiplist %p", key, sl);
     node_t *preds[MAX_LEVEL+1];
     node_t *item = find_preds(preds, NULL, -1, sl, key, TRUE);
@@ -363,17 +365,17 @@ uint64_t sl_remove (skiplist_t *sl, void *key) {
         node_t *old_next = item->next[level];
         do {
             next = old_next;
-            old_next = SYNC_CAS(&item->next[level], next, TAG_VALUE(next));
-            if (IS_TAGGED(old_next)) {
+            old_next = SYNC_CAS(&item->next[level], next, TAG_VALUE(next, TAG1));
+            if (IS_TAGGED(old_next, TAG1)) {
                 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));
+        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))) != item) {
+        if ((other = SYNC_CAS(&pred->next[level], item, STRIP_TAG(next, TAG1))) != 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.
@@ -381,7 +383,7 @@ uint64_t sl_remove (skiplist_t *sl, void *key) {
                 continue; // <pred> points past <item> to the end of the list; go on to the next level.
 
             int d = -1;
-            if (!IS_TAGGED(other)) {
+            if (!IS_TAGGED(other, TAG1)) {
                 if (EXPECT_TRUE(sl->key_type == NULL)) {
                     d = (uint64_t)item->key - (uint64_t)other->key;
                 } else {
@@ -401,8 +403,8 @@ uint64_t sl_remove (skiplist_t *sl, void *key) {
     node_t *old_next = item->next[0];
     do {
         next = old_next;
-        old_next = SYNC_CAS(&item->next[0], next, TAG_VALUE(next));
-        if (IS_TAGGED(old_next)) {
+        old_next = SYNC_CAS(&item->next[0], next, TAG_VALUE(next, TAG1));
+        if (IS_TAGGED(old_next, TAG1)) {
             TRACE("s2", "sl_remove: %p is already marked for removal by another thread at level 0", item, 0);
             return DOES_NOT_EXIST;
         }
@@ -411,12 +413,12 @@ uint64_t sl_remove (skiplist_t *sl, void *key) {
 
     // 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. 
-    uint64_t val = SYNC_SWAP(&item->val, DOES_NOT_EXIST); 
+    map_val_t val = SYNC_SWAP(&item->val, 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));
-    if (SYNC_CAS(&pred->next[0], item, STRIP_TAG(next))) {
+    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: 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) {
@@ -436,8 +438,8 @@ void sl_print (skiplist_t *sl) {
         int i = 0;
         while (item) {
             node_t *next = item->next[level];
-            printf("%s%p ", IS_TAGGED(next) ? "*" : "", item);
-            item = (node_t *)STRIP_TAG(next);
+            printf("%s%p ", IS_TAGGED(next, TAG1) ? "*" : "", item);
+            item = (node_t *)STRIP_TAG(next, TAG1);
             if (i++ > 30) {
                 printf("...");
                 break;
@@ -449,7 +451,7 @@ void sl_print (skiplist_t *sl) {
     node_t *item = sl->head;
     int i = 0;
     while (item) {
-        int is_marked = IS_TAGGED(item->next[0]);
+        int is_marked = IS_TAGGED(item->next[0], TAG1);
         printf("%s%p:%p ", is_marked ? "*" : "", item, item->key);
         if (item != sl->head) {
             printf("[%d]", item->top_level);
@@ -457,18 +459,45 @@ void sl_print (skiplist_t *sl) {
             printf("[HEAD]");
         }
         for (int level = 1; level <= item->top_level; ++level) {
-            node_t *next = (node_t *)STRIP_TAG(item->next[level]);
-            is_marked = IS_TAGGED(item->next[0]);
+            node_t *next = (node_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)
                 break;
         }
         printf("\n");
         fflush(stdout);
-        item = (node_t *)STRIP_TAG(item->next[0]);
+        item = (node_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);
+    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];
+    while (item != NULL && IS_TAGGED(item->next[0], TAG1)) {
+        item = (node_t *)STRIP_TAG(item->next[0], TAG1);
+    }
+    if (item == NULL) {
+        iter->next[0] = NULL;
+        return DOES_NOT_EXIST;
+    }
+    iter->next[0] = item->next[0];
+    if (key_ptr != NULL) {
+        *key_ptr = item->key;
+    }
+    return item->val;
+}
+
+void sl_iter_free (sl_iter_t *iter) {
+    nbd_free(iter);
+}