Implement second-level cache for escaped netnames.

While it's a bit of an encapsulation leak (see comment in
CONNECTION_SUBGRAPH::driverName()), it more than doubles undo/redo
performance in documents with *lots* of nets.

eeschema/connection_graph.cpp

@@ -337,6 +337,7 @@ wxString CONNECTION_SUBGRAPH::driverName( SCH_ITEM* aItem ) const
     case SCH_LABEL_T:
     case SCH_GLOBAL_LABEL_T:
     case SCH_HIER_LABEL_T:
+        // NB: any changes here will need corresponding changes in SCH_LABEL_BASE::cacheShownText()
         return EscapeString( static_cast<SCH_TEXT*>( aItem )->GetShownText( &m_sheet, false ),
                              CTX_NETNAME );
 
@@ -357,6 +358,9 @@ wxString CONNECTION_SUBGRAPH::driverName( SCH_ITEM* aItem ) const
 
 const wxString& CONNECTION_SUBGRAPH::GetNameForDriver( SCH_ITEM* aItem ) const
 {
+    if( aItem->HasCachedDriverName() )
+        return aItem->GetCachedDriverName();
+
     auto it = m_driver_name_cache.find( aItem );
 
     if( it != m_driver_name_cache.end() )

eeschema/sch_item.cpp

@@ -253,6 +253,13 @@ SCH_CONNECTION* SCH_ITEM::GetOrInitConnection( const SCH_SHEET_PATH& aSheet,
 }
 
 
+const wxString& SCH_ITEM::GetCachedDriverName() const
+{
+    static wxString s_empty;
+    return s_empty;
+}
+
+
 void SCH_ITEM::SwapData( SCH_ITEM* aItem )
 {
     UNIMPLEMENTED_FOR( GetClass() );

eeschema/sch_item.h

@@ -430,6 +430,9 @@ public:
     /// Updates the connection graph for all connections in this item
     void SetConnectionGraph( CONNECTION_GRAPH* aGraph );
 
+    virtual bool HasCachedDriverName() const { return false; }
+    virtual const wxString& GetCachedDriverName() const;
+
     virtual void SetLastResolvedState( const SCH_ITEM* aItem ) { }
 
     std::shared_ptr<NETCLASS> GetEffectiveNetClass( const SCH_SHEET_PATH* aSheet = nullptr ) const;

eeschema/sch_label.cpp

@@ -691,6 +691,27 @@ bool SCH_LABEL_BASE::ResolveTextVar( const SCH_SHEET_PATH* aPath, wxString* toke
 }
 
 
+bool SCH_LABEL_BASE::HasCachedDriverName() const
+{
+    return !HasTextVars();
+}
+
+
+const wxString& SCH_LABEL_BASE::GetCachedDriverName() const
+{
+    return m_cached_driver_name;
+}
+
+
+void SCH_LABEL_BASE::cacheShownText()
+{
+    EDA_TEXT::cacheShownText();
+
+    if( !HasTextVars() )
+        m_cached_driver_name = EscapeString( EDA_TEXT::GetShownText( true, 0 ), CTX_NETNAME );
+}
+
+
 wxString SCH_LABEL_BASE::GetShownText( const SCH_SHEET_PATH* aPath, bool aAllowExtraText,
                                        int aDepth ) const
 {

eeschema/sch_label.h

@@ -156,6 +156,9 @@ public:
         return GetShownText( nullptr, aAllowExtraText, aDepth );
     }
 
+    bool HasCachedDriverName() const override;
+    const wxString& GetCachedDriverName() const override;
+
     void RunOnChildren( const std::function<void( SCH_ITEM* )>& aFunction ) override;
 
     INSPECT_RESULT Visit( INSPECTOR inspector, void* testData,
@@ -231,6 +234,9 @@ public:
      */
     virtual bool AutoRotateOnPlacementSupported() const = 0;
 
+protected:
+    void cacheShownText() override;
+
 protected:
     std::vector<SCH_FIELD>  m_fields;
 
@@ -241,6 +247,8 @@ protected:
     bool                    m_autoRotateOnPlacement = false;
 
     mutable COLOR4D         m_lastResolvedColor;
+
+    wxString                m_cached_driver_name;
 };
 
 

eeschema/sch_text.cpp

@@ -356,8 +356,8 @@ wxString SCH_TEXT::GetShownText( const SCH_SHEET_PATH* aPath, bool aAllowExtraTe
 
     if( aPath )
         sheet = aPath->Last();
-    else if( Schematic() )
-        sheet = Schematic()->CurrentSheet().Last();
+    else if( SCHEMATIC* schematic = Schematic() )
+        sheet = schematic->CurrentSheet().Last();
 
     std::function<bool( wxString* )> textResolver =
             [&]( wxString* token ) -> bool

include/eda_text.h

@@ -368,7 +368,7 @@ protected:
 
     virtual const KIFONT::METRICS& getFontMetrics() const;
 
-    void cacheShownText();
+    virtual void cacheShownText();
 
     /**
      * Print each line of this EDA_TEXT.