Client side caching: split invalidation into key / slot.

src/server.c

@@ -3401,6 +3401,10 @@ int processCommand(client *c) {
         }
     }
 
+    /* Make sure to use a reasonable amount of memory for client side
+     * caching metadata. */
+    if (server.tracking_clients) trackingLimitUsedSlots();
+
     /* Don't accept write commands if there are problems persisting on disk
      * and if this is a master instance. */
     int deny_write_type = writeCommandsDeniedByDiskError();