improve performance for scan command when matching data type (#12395)

Move the TYPE filtering to the scan callback so that avoided the
`lookupKey` operation. This is the follow-up to #12209 . In this thread
we introduced two breaking changes：
1. we will not attempt to do lazy expire (delete) a key that was
filtered by not matching the TYPE (like we already do for MATCH
pattern).
2. when the specified key TYPE filter is an unknown type, server will
reply a error immediately instead of doing a full scan that comes back
empty handed.

src/db.c

@@ -944,11 +944,10 @@ void scanCallback(void *privdata, const dictEntry *de) {
     serverAssert(!((data->type != LLONG_MAX) && o));
 
     /* Filter an element if it isn't the type we want. */
-    /* TODO: uncomment in redis 8.0
     if (!o && data->type != LLONG_MAX) {
         robj *rval = dictGetVal(de);
         if (!objectTypeCompare(rval, data->type)) return;
-    }*/
+    }
 
     /* Filter element if it does not match the pattern. */
     void *keyStr = dictGetKey(de);
@@ -1095,9 +1094,8 @@ void scanGenericCommand(client *c, robj *o, unsigned long long cursor) {
             typename = c->argv[i+1]->ptr;
             type = getObjectTypeByName(typename);
             if (type == LLONG_MAX) {
-                /* TODO: uncomment in redis 8.0
                 addReplyErrorFormat(c, "unknown type name '%s'", typename);
-                return; */
+                return;
             }
             i+= 2;
         } else if (!strcasecmp(c->argv[i]->ptr, "novalues")) {
@@ -1285,16 +1283,7 @@ void scanGenericCommand(client *c, robj *o, unsigned long long cursor) {
         while ((ln = listNext(&li))) {
             sds key = listNodeValue(ln);
             initStaticStringObject(kobj, key);
-            /* Filter an element if it isn't the type we want. */
+            if (expireIfNeeded(c->db, &kobj, 0)) {
-            /* TODO: remove this in redis 8.0 */
-            if (typename) {
-                robj* typecheck = lookupKeyReadWithFlags(c->db, &kobj, LOOKUP_NOTOUCH|LOOKUP_NONOTIFY);
-                if (!typecheck || !objectTypeCompare(typecheck, type)) {
-                    listDelNode(keys, ln);
-                }
-                continue;
-            }
-            if (expireIfNeeded(c->db, &kobj, 0) != KEY_VALID) {
                 listDelNode(keys, ln);
             }
         }

tests/unit/scan.tcl

@@ -109,25 +109,9 @@ proc test_scan {type} {
 
         after 2
 
-        # TODO: remove this in redis 8.0
+        assert_error "*unknown type name*" {r scan 0 type "string1"}
-        set cur 0
-        set keys {}
-        while 1 {
-            set res [r scan $cur type "string1"]
-            set cur [lindex $res 0]
-            set k [lindex $res 1]
-            lappend keys {*}$k
-            if {$cur == 0} break
-        }
-
-        assert_equal 0 [llength $keys]
-        # make sure that expired key have been removed by scan command
-        assert_equal 1000 [scan [regexp -inline {keys\=([\d]*)} [r info keyspace]] keys=%d]
-
-        # TODO: uncomment in redis 8.0
-        #assert_error "*unknown type name*" {r scan 0 type "string1"}
         # expired key will be no touched by scan command
-        #assert_equal 1001 [scan [regexp -inline {keys\=([\d]*)} [r info keyspace]] keys=%d]
+        assert_equal 1001 [scan [regexp -inline {keys\=([\d]*)} [r info keyspace]] keys=%d]
         r debug set-active-expire 1
     } {OK} {needs:debug}
 
@@ -191,11 +175,8 @@ proc test_scan {type} {
 
         assert_equal 1000 [llength $keys]
 
-        # make sure that expired key have been removed by scan command
-        assert_equal 1000 [scan [regexp -inline {keys\=([\d]*)} [r info keyspace]] keys=%d]
-        # TODO: uncomment in redis 8.0
         # make sure that only the expired key in the type match will been removed by scan command
-        #assert_equal 1001 [scan [regexp -inline {keys\=([\d]*)} [r info keyspace]] keys=%d]
+        assert_equal 1001 [scan [regexp -inline {keys\=([\d]*)} [r info keyspace]] keys=%d]
 
         r debug set-active-expire 1
     } {OK} {needs:debug}