add prototypes of loadStoredObject and

some relevant helpers in replicateddb

dbms/src/Databases/DatabaseReplicated.cpp

@@ -190,4 +190,26 @@ void DatabaseReplicated::drop(const Context & context)
     // zookeeper path. does it work recursively? hope so...
 }
 
+void DatabaseOrdinary::loadStoredObjects(
+    Context & context,
+    bool has_force_restore_data_flag)
+{
+    syncReplicaState(context);
+    updateMetadata(context);
+
+    DatabaseOrdinary::loadStoredObjects(context, has_force_restore_data_flag);
+
+}
+
+// sync replica's zookeeper metadata
+void syncReplicaState(Context & context) {
+
+}
+
+// get the up to date metadata from zookeeper to local metadata dir
+// for replicated (only?) tables
+void updateMetadata(Context & context) {
+
+}
+
 }

dbms/src/Databases/DatabaseReplicated.h

@@ -0,0 +1,61 @@
+#pragma once
+
+#include <Databases/DatabaseOrdinary.h>
+#include <Common/randomSeed.h>
+#include <Common/ZooKeeper/ZooKeeper.h>
+
+namespace DB
+{
+/** Replicated database engine.
+  * It stores tables list using list of .sql files,
+  *  that contain declaration of table represented by SQL ATTACH TABLE query
+  *  and operation log in zookeeper
+  */
+class DatabaseReplicated : public DatabaseOrdinary
+{
+public:
+    DatabaseReplicated(const String & name_, const String & metadata_path_, const String & zookeeper_path_, const String & replica_name_, const Context & context);
+
+    String getEngineName() const override { return "Replicated"; }
+
+    void createTable(
+        const Context & context,
+        const String & table_name,
+        const StoragePtr & table,
+        const ASTPtr & query) override;
+
+    void removeTable(
+        const Context & context,
+        const String & table_name) override;
+
+    void renameTable(
+        const Context & context,
+        const String & table_name,
+        IDatabase & to_database,
+        const String & to_table_name,
+        TableStructureWriteLockHolder & lock) override;
+
+    void drop(const Context & context) override;
+
+    void loadStoredObjects(
+        Context & context,
+        bool has_force_restore_data_flag) override;
+
+private:
+    String zookeeper_path;
+    String replica_name;
+    String replica_path;
+
+    zkutil::ZooKeeperPtr current_zookeeper;        /// Use only the methods below.
+    mutable std::mutex current_zookeeper_mutex;    /// To recreate the session in the background thread.
+
+    zkutil::ZooKeeperPtr tryGetZooKeeper() const;
+    zkutil::ZooKeeperPtr getZooKeeper() const;
+    void setZooKeeper(zkutil::ZooKeeperPtr zookeeper);
+
+    void syncReplicaState(Context & context);
+
+    void updateMetadata(Context & context);
+};
+
+}