Make the database dumper use only Vertices

Reviewers: teon.banek

Reviewed By: teon.banek

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D2539

src/database/single_node/dump.cpp

@@ -199,7 +199,7 @@ CypherDumpGenerator::CypherDumpGenerator(query::DbAccessor *dba)
   unique_constraints_state_.emplace(dba->ListUniqueConstraints());
 #endif
   vertices_state_.emplace(dba->Vertices(storage::View::OLD));
-  edges_state_.emplace(dba->Edges(storage::View::OLD));
+  edges_state_.emplace(dba->Vertices(storage::View::OLD));
 }
 
 bool CypherDumpGenerator::NextQuery(std::ostream *os) {
@@ -225,7 +225,7 @@ bool CypherDumpGenerator::NextQuery(std::ostream *os) {
     DumpVertex(os, dba_, *vertices_state_->GetCurrentAndAdvance());
     return true;
   } else if (!edges_state_->ReachedEnd()) {
-    DumpEdge(os, dba_, *edges_state_->GetCurrentAndAdvance());
+    DumpEdge(os, dba_, edges_state_->GetCurrentAndAdvance());
     return true;
   } else if (!vertices_state_->Empty() && !cleaned_internal_index_) {
     *os << "DROP INDEX ON :" << kInternalVertexLabel << "("
@@ -242,4 +242,29 @@ bool CypherDumpGenerator::NextQuery(std::ostream *os) {
   return false;
 }
 
+void CypherDumpGenerator::EdgesState::FindNext() {
+  current_edge_ = std::nullopt;
+  if (edges_list_state_ && !edges_list_state_->ReachedEnd()) {
+    current_edge_ = *edges_list_state_->GetCurrentAndAdvance();
+    return;
+  }
+  while (!vertices_state_->ReachedEnd()) {
+    auto vertex = *vertices_state_->GetCurrentAndAdvance();
+    auto maybe_edges = vertex.OutEdges(storage::View::OLD);
+    CHECK(maybe_edges.HasValue()) << "Invalid database state!";
+    auto &edges = maybe_edges.GetValue();
+    // We convert the itertools object to a list of edge accessors here because
+    // itertools have suspicious object lifetime handling.
+    std::vector<query::EdgeAccessor> edges_list;
+    for (auto edge : edges) {
+      edges_list.push_back(edge);
+    }
+    if (!edges_list.empty()) {
+      edges_list_state_.emplace(std::move(edges_list));
+      current_edge_ = *edges_list_state_->GetCurrentAndAdvance();
+      break;
+    }
+  }
+}
+
 }  // namespace database

src/database/single_node/dump.hpp

@@ -54,7 +54,7 @@ class CypherDumpGenerator {
 
     bool ReachedEnd() const { return current_ == end_; }
 
-    // Returns true iff the container is empty.
+    // Returns true if the container is empty.
     bool Empty() const { return empty_; }
 
    private:
@@ -67,6 +67,44 @@ class CypherDumpGenerator {
     bool empty_;
   };
 
+  class EdgesState {
+   private:
+    using TVertices = decltype(std::declval<query::DbAccessor>().Vertices(
+        std::declval<storage::View>()));
+
+   public:
+    explicit EdgesState(TVertices vertices)
+        : vertices_state_(std::move(vertices)) {
+      FindNext();
+    }
+
+    EdgesState(const EdgesState &other) = delete;
+    // NOLINTNEXTLINE(hicpp-noexcept-move,performance-noexcept-move-constructor)
+    EdgesState(EdgesState &&other) = default;
+    EdgesState &operator=(const EdgesState &other) = delete;
+    EdgesState &operator=(EdgesState &&other) = delete;
+    ~EdgesState() = default;
+
+    auto GetCurrentAndAdvance() {
+      auto edge = *current_edge_;
+      FindNext();
+      return edge;
+    }
+
+    bool ReachedEnd() const { return !current_edge_; }
+
+    // Returns true if the container is empty.
+    bool Empty() const { return !current_edge_; }
+
+   private:
+    void FindNext();
+
+    std::optional<ContainerState<TVertices>> vertices_state_;
+    std::optional<ContainerState<std::vector<query::EdgeAccessor>>>
+        edges_list_state_;
+    std::optional<query::EdgeAccessor> current_edge_;
+  };
+
   query::DbAccessor *dba_;
 
   bool created_internal_index_;
@@ -82,8 +120,7 @@ class CypherDumpGenerator {
 #endif
   std::optional<ContainerState<decltype(dba_->Vertices(storage::View::OLD))>>
       vertices_state_;
-  std::optional<ContainerState<decltype(dba_->Edges(storage::View::OLD))>>
-      edges_state_;
+  std::optional<EdgesState> edges_state_;
 };
 
 }  // namespace database

src/query/db_accessor.hpp

@@ -522,27 +522,6 @@ class DbAccessor final {
     Iterator end() { return Iterator(iterable_.end()); }
   };
 
-  class EdgesIterable final {
-   public:
-    class Iterator final {
-     public:
-      EdgeAccessor operator*() const {
-        throw utils::NotYetImplemented("operator*");
-      }
-
-      Iterator &operator++() { throw utils::NotYetImplemented("operator++"); }
-
-      bool operator==(const Iterator &other) const {
-        throw utils::NotYetImplemented("operator==");
-      }
-
-      bool operator!=(const Iterator &other) const { return !(other == *this); }
-    };
-
-    Iterator begin() { throw utils::NotYetImplemented("begin"); }
-    Iterator end() { throw utils::NotYetImplemented("end"); }
-  };
-
  public:
   explicit DbAccessor(storage::Storage::Accessor *accessor)
       : accessor_(accessor) {}
@@ -569,10 +548,6 @@ class DbAccessor final {
         accessor_->Vertices(label, property, lower, upper, view));
   }
 
-  EdgesIterable Edges(storage::View view) {
-    throw utils::NotYetImplemented("Edges");
-  }
-
   VertexAccessor InsertVertex() {
     return VertexAccessor(accessor_->CreateVertex());
   }
@@ -785,12 +760,6 @@ class DbAccessor final {
     return VerticesIterable<decltype(vertices)>(std::move(vertices));
   }
 
-  auto Edges(storage::View view) {
-    // TODO: Exceptions?
-    return iter::imap([](const auto &e) { return EdgeAccessor(e); },
-                      dba_->Edges(view == storage::View::NEW));
-  }
-
   storage::Property NameToProperty(const std::string_view &name) {
     return dba_->Property(std::string(name));
   }