Storage::RecordAccessor - added SwitchNew, SwitchOld and Reconstruct API and placeholder implementations

Reviewers: teon.banek, mislav.bradac, buda

Reviewed By: mislav.bradac

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D205

src/storage/record_accessor.cpp

@@ -61,6 +61,23 @@ const uint64_t RecordAccessor<TRecord>::temporary_id() const {
   return (uint64_t) vlist_;
 }
 
+template <typename TRecord>
+RecordAccessor<TRecord> &RecordAccessor<TRecord>::SwitchNew() {
+  // TODO implement
+  return *this;
+}
+
+template <typename TRecord>
+RecordAccessor<TRecord> &RecordAccessor<TRecord>::SwitchOld() {
+  // TODO implement
+  return *this;
+}
+
+template <typename TRecord>
+void RecordAccessor<TRecord>::Reconstruct() {
+  // TODO implement
+}
+
 template <typename TRecord>
 TRecord &RecordAccessor<TRecord>::update() {
   db_accessor().update(*this);

src/storage/record_accessor.hpp

@@ -148,6 +148,31 @@ class RecordAccessor {
    */
   const uint64_t temporary_id() const;
 
+  /*
+   * Switches this record accessor to use the latest
+   * version (visible to the current transaction+command).
+   *
+   * @return A reference to this.
+   */
+  RecordAccessor<TRecord> &SwitchNew();
+
+  /**
+   * Switches this record accessor to use the old
+   * (not updated) version visible to the current transaction+command.
+   *
+   * @return A reference to this.
+   */
+  RecordAccessor<TRecord> &SwitchOld();
+
+  /**
+   * Reconstructs the internal state of the record
+   * accessor so it uses the versions appropriate
+   * to this transaction+command.
+   *
+   * TODO consider what it does after delete+advance_command
+   */
+  void Reconstruct();
+
  protected:
   /**
    * Returns the update-ready version of the record.