ZSET B+ Tree PR 3: Replace skiplist with FB+ Tree implementation

.config/typos.toml

@@ -15,6 +15,8 @@ optin = "optin"
 smove = "smove"
 Parth = "Parth" # seems like the spellchecker does not like it is similar to "Path"
 nd = "nd"
+Ba = "Ba"
+Addd = "Addd"
 
 [default]
 extend-ignore-re = [

cmake/Modules/SourceFiles.cmake

@@ -33,7 +33,7 @@ set(VALKEY_SERVER_SRCS
     ${CMAKE_SOURCE_DIR}/src/t_list.c
     ${CMAKE_SOURCE_DIR}/src/t_set.c
     ${CMAKE_SOURCE_DIR}/src/t_zset.c
-    ${CMAKE_SOURCE_DIR}/src/skiplist.c
+    ${CMAKE_SOURCE_DIR}/src/fbtree.c
     ${CMAKE_SOURCE_DIR}/src/ordered_index.c
     ${CMAKE_SOURCE_DIR}/src/t_hash.c
     ${CMAKE_SOURCE_DIR}/src/config.c

src/Makefile

@@ -568,7 +568,7 @@ ENGINE_SERVER_OBJ = \
     t_stream.o \
     t_string.o \
     t_zset.o \
-    skiplist.o \
+    fbtree.o \
     threads_mngr.o \
     timeout.o \
     tls.o \

src/aof.c

@@ -2021,7 +2021,7 @@ int rewriteSortedSetObject(rio *r, robj *key, robj *o) {
             if (++count == AOF_REWRITE_ITEMS_PER_CMD) count = 0;
             items--;
         }
-    } else if (o->encoding == OBJ_ENCODING_SKIPLIST) {
+    } else if (o->encoding == OBJ_ENCODING_BTREE) {
         zset *zs = objectGetVal(o);
         hashtableIterator iter;
         hashtableInitIterator(&iter, zs->ht, 0);

src/db.c

@@ -1259,7 +1259,7 @@ void scanGenericCommandWithOptions(client *c, robj *o, unsigned long long cursor
     } else if (o->type == OBJ_HASH && o->encoding == OBJ_ENCODING_HASHTABLE) {
         ht = objectGetVal(o);
         free_callback = NULL;
-    } else if (o->type == OBJ_ZSET && o->encoding == OBJ_ENCODING_SKIPLIST) {
+    } else if (o->type == OBJ_ZSET && o->encoding == OBJ_ENCODING_BTREE) {
         zset *zs = objectGetVal(o);
         ht = zs->ht;
         /* scanning ZSET allocates temporary strings even though it's a dict */

src/debug.c

@@ -210,7 +210,7 @@ void xorObjectDigest(serverDb *db, robj *keyobj, unsigned char *digest, robj *o)
                 xorDigest(digest, eledigest, 20);
                 zzlNext(zl, &eptr, &sptr);
             }
-        } else if (o->encoding == OBJ_ENCODING_SKIPLIST) {
+        } else if (o->encoding == OBJ_ENCODING_BTREE) {
             zset *zs = objectGetVal(o);
             hashtableIterator iter;
             hashtableInitIterator(&iter, zs->ht, 0);
@@ -976,7 +976,7 @@ void debugCommand(client *c) {
         /* Get the hashtable reference from the object, if possible. */
         hashtable *ht = NULL;
         switch (o->encoding) {
-        case OBJ_ENCODING_SKIPLIST: {
+        case OBJ_ENCODING_BTREE: {
             zset *zs = objectGetVal(o);
             ht = zs->ht;
         } break;
@@ -1186,7 +1186,7 @@ void serverLogObjectDebugInfo(const robj *o) {
         serverLog(LL_WARNING, "Hash size: %d", (int)hashTypeLength(o));
     } else if (o->type == OBJ_ZSET) {
         serverLog(LL_WARNING, "Sorted set size: %d", (int)zsetLength(o));
-        if (o->encoding == OBJ_ENCODING_SKIPLIST) {
+        if (o->encoding == OBJ_ENCODING_BTREE) {
             /* Not declared in ordered_index.h — debug-only introspection. */
             extern int orderedIndexGetHeight(const OrderedIndex *oi);
             serverLog(LL_WARNING, "Index height: %d", orderedIndexGetHeight(((const zset *)o->ptr)->oi));

src/defrag.c

@@ -387,7 +387,7 @@ static long scanLaterList(robj *ob, unsigned long *cursor, monotime endtime) {
 }
 
 static void scanLaterZset(robj *ob, unsigned long *cursor) {
-    serverAssert(ob->type == OBJ_ZSET && ob->encoding == OBJ_ENCODING_SKIPLIST);
+    serverAssert(ob->type == OBJ_ZSET && ob->encoding == OBJ_ENCODING_BTREE);
     zset *zs = (zset *)objectGetVal(ob);
     *cursor = orderedIndexScanDefrag(zs->oi, *cursor, defragZsetNodeCallback, zs->ht, activeDefragAlloc);
 }
@@ -424,8 +424,8 @@ static void defragQuicklist(robj *ob) {
         activeDefragQuickListNodes(ql);
 }
 
-static void defragZsetSkiplist(robj *ob) {
-    serverAssert(ob->type == OBJ_ZSET && ob->encoding == OBJ_ENCODING_SKIPLIST);
+static void defragZset(robj *ob) {
+    serverAssert(ob->type == OBJ_ZSET && ob->encoding == OBJ_ENCODING_BTREE);
     zset *zs = (zset *)objectGetVal(ob);
 
     zset *newzs;
@@ -698,8 +698,8 @@ static void defragKey(defragKeysCtx *ctx, robj **elemref) {
     } else if (ob->type == OBJ_ZSET) {
         if (ob->encoding == OBJ_ENCODING_LISTPACK) {
             if ((newzl = activeDefragAlloc(objectGetVal(ob)))) objectSetVal(ob, newzl);
-        } else if (ob->encoding == OBJ_ENCODING_SKIPLIST) {
-            defragZsetSkiplist(ob);
+        } else if (ob->encoding == OBJ_ENCODING_BTREE) {
+            defragZset(ob);
         } else {
             serverPanic("Unknown sorted set encoding");
         }
@@ -767,7 +767,7 @@ static int defragLaterItem(robj *ob, unsigned long *cursor, monotime endtime, in
             return scanLaterList(ob, cursor, endtime);
         } else if (ob->type == OBJ_SET && ob->encoding == OBJ_ENCODING_HASHTABLE) {
             scanLaterSet(ob, cursor);
-        } else if (ob->type == OBJ_ZSET && ob->encoding == OBJ_ENCODING_SKIPLIST) {
+        } else if (ob->type == OBJ_ZSET && ob->encoding == OBJ_ENCODING_BTREE) {
             scanLaterZset(ob, cursor);
         } else if (ob->type == OBJ_HASH && ob->encoding == OBJ_ENCODING_HASHTABLE) {
             scanLaterHash(ob, cursor);