Unify code for refreshing Virtual Trees in a new helper method InvalidateVT. Fixes issue #1789 and issue #1790.

* Don't try to access a passed tree if it has been destroyed by some earlier event.
* Don't try to access registry in DoDisconnect after key has been closed.
* Now that DoDisconnect lives in FormDestroy it is save to call it slightly earlier, before registry has been closed. There should be no later paint events which will trigger random database queries.

source/column_selection.pas

@@ -87,8 +87,7 @@ begin
     if not chklistColumns.Checked[i] then
       Mainform.DataGridHiddenColumns.Add(chklistColumns.Items[i]);
   end;
-  Mainform.DataGrid.Tag := VTREE_NOTLOADED_PURGECACHE;
+  InvalidateVT(Mainform.DataGrid, VTREE_NOTLOADED_PURGECACHE, False);
-  Mainform.DataGrid.Invalidate;
   btnCancel.OnClick(Sender);
 end;
 

source/data_sorting.pas

@@ -315,8 +315,7 @@ procedure TDataSortingForm.btnOKClick(Sender: TObject);
 begin
   // TODO: apply ordering
   Mainform.DataGridSortColumns := OrderColumns;
-  Mainform.DataGrid.Tag := VTREE_NOTLOADED_PURGECACHE;
+  InvalidateVT(Mainform.DataGrid, VTREE_NOTLOADED_PURGECACHE, False);
-  Mainform.DataGrid.Invalidate;
   btnCancel.OnClick(Sender);
 end;
 

source/helpers.pas

@@ -249,6 +249,7 @@ type
   function GetIndexIcon(IndexType: String): Integer;
   function KeyPressed(Code: Integer): Boolean;
   function GeneratePassword(Len: Integer): String;
+  procedure InvalidateVT(VT: TVirtualStringTree; RefreshTag: Integer; ImmediateRepaint: Boolean);
 
 var
   MainReg: TRegistry;
@@ -3442,6 +3443,19 @@ begin
 end;
 
 
+procedure InvalidateVT(VT: TVirtualStringTree; RefreshTag: Integer; ImmediateRepaint: Boolean);
+begin
+  // Avoid AVs in OnDestroy events
+  if not Assigned(VT) then
+    Exit;
+  VT.Tag := RefreshTag;
+  if ImmediateRepaint then
+    VT.Repaint
+  else
+    VT.Invalidate;
+end;
+
+
 end.
 
 

source/main.pas

@@ -1121,7 +1121,7 @@ procedure TMainForm.FormDestroy(Sender: TObject);
 var
   filename : String;
 begin
-  // Destroy editors and dialogs. Must be done before connection gets closed, as some destructors do SQL stuff. 
+  // Destroy editors and dialogs. Must be done before connection gets closed, as some destructors do SQL stuff.
   FreeAndNil(RoutineEditor);
   FreeAndNil(TableToolsDialog);
   FreeAndNil(UserManagerForm);
@@ -1135,8 +1135,15 @@ begin
   FreeAndNil(CreateDatabaseForm);
   FreeAndNil(SearchReplaceDialog);
 
+  // Clearing query and browse data.
+  SetLength(DataGridResult.Rows, 0);
+  SetLength(DataGridResult.Columns, 0);
+
+  // Close database connection
+  DoDisconnect;
+
+  // Save various settings
   OpenRegistry;
-  // Position of Toolbars
   MainReg.WriteInteger(REGNAME_TOOLBAR2LEFT, ToolBarStandard.Left);
   MainReg.WriteInteger(REGNAME_TOOLBAR2TOP, ToolBarStandard.Top);
   MainReg.WriteInteger(REGNAME_TOOLBARDATALEFT, ToolBarData.Left);
@@ -1145,29 +1152,17 @@ begin
   MainReg.WriteInteger(REGNAME_TOOLBARQUERYTOP, ToolBarQuery.Top);
   MainReg.WriteBool(REGNAME_STOPONERRORSINBATCH, actQueryStopOnErrors.Checked);
   MainReg.WriteBool(REGNAME_BLOBASTEXT, actBlobAsText.Checked);
-
-  // Save delimiter
   MainReg.WriteString( REGNAME_DELIMITER, Delimiter );
-
   MainReg.WriteInteger( REGNAME_QUERYMEMOHEIGHT, pnlQueryMemo.Height );
   MainReg.WriteInteger( REGNAME_QUERYHELPERSWIDTH, pnlQueryHelpers.Width );
   MainReg.WriteInteger( REGNAME_DBTREEWIDTH, pnlLeft.width );
   MainReg.WriteInteger( REGNAME_SQLOUTHEIGHT, SynMemoSQLLog.Height );
-
-  // Filter panel
   MainReg.WriteBool(REGNAME_FILTERACTIVE, pnlFilterVT.Tag=Integer(True));
-
-  // Save width of probably resized columns of all VirtualTrees
   SaveListSetup(ListVariables);
   SaveListSetup(ListStatus);
   SaveListSetup(ListProcesses);
   SaveListSetup(ListCommandStats);
   SaveListSetup(ListTables);
-
-  debug('mem: clearing query and browse data.');
-  SetLength(DataGridResult.Rows, 0);
-  SetLength(DataGridResult.Columns, 0);
-
   saveWindowConfig;
 
   filename := GetTempDir+'\'+APPNAME+'-preview.';
@@ -1183,10 +1178,6 @@ begin
     MainReg.CloseKey;
     MainReg.Free;
   end;
-
-  // Close database connection at the very end, as above stuff can easily
-  // trigger some database query
-  DoDisconnect;
 end;
 
 
@@ -1815,6 +1806,10 @@ end;
 
 procedure TMainForm.DoDisconnect;
 begin
+  // Do nothing in case user clicked Cancel on session manager
+  if (not Assigned(Connection)) or (not Connection.Active) then
+    Exit;
+
   // Open server-specific registry-folder.
   // relative from already opened folder!
   OpenRegistry(SessionName);
@@ -1835,18 +1830,17 @@ begin
   SetLength(DataGridSortColumns, 0);
 
   // Closing connection
-  if Assigned(Connection) then
+  Connection.Active := False;
-    FreeAndNil(Connection);
 
   if prefLogToFile then
     DeactivateFileLogging;
 
   // Invalidate list contents
-  ListVariables.Tag := VTREE_NOTLOADED;
+  InvalidateVT(ListVariables, VTREE_NOTLOADED, False);
-  ListStatus.Tag := VTREE_NOTLOADED;
+  InvalidateVT(ListStatus, VTREE_NOTLOADED, False);
-  ListProcesses.Tag := VTREE_NOTLOADED;
+  InvalidateVT(ListProcesses, VTREE_NOTLOADED, False);
-  ListCommandstats.Tag := VTREE_NOTLOADED;
+  InvalidateVT(ListCommandstats, VTREE_NOTLOADED, False);
-  ListTables.Tag := VTREE_NOTLOADED;
+  InvalidateVT(ListTables, VTREE_NOTLOADED, False);
 
   Application.Title := APPNAME;
 end;
@@ -1957,10 +1951,8 @@ begin
     ActiveQueryTab.MemoFilename := '';
     ActiveQueryTab.Memo.Modified := False;
   end;
-  if m = SynMemoFilter then begin
+  if m = SynMemoFilter then
-    DataGrid.Tag := VTREE_NOTLOADED_PURGECACHE;
+    InvalidateVT(DataGrid, VTREE_NOTLOADED_PURGECACHE, False);
-    DataGrid.Invalidate;
-  end;
 end;
 
 procedure TMainForm.actTableToolsExecute(Sender: TObject);
@@ -2562,8 +2554,8 @@ begin
     end;
 
     Result := True;
-    if Assigned(Connection) then
+    DoDisconnect;
-      DoDisconnect;
+    FreeAndNil(Connection);
     Connection := ConnectionAttempt;
     SessionName := Session;
   end;
@@ -2767,15 +2759,11 @@ begin
       List := ListProcesses
     else
       List := ListCommandStats;
-    List.Tag := VTREE_NOTLOADED;
+    InvalidateVT(List, VTREE_NOTLOADED, True);
-    List.Repaint;
+  end else if tab1 = tabDatabase then
-  end else if tab1 = tabDatabase then begin
+    InvalidateVT(ListTables, VTREE_NOTLOADED_PURGECACHE, False)
-    ListTables.Tag := VTREE_NOTLOADED_PURGECACHE;
+  else if tab1 = tabData then
-    ListTables.Invalidate;
+    InvalidateVT(DataGrid, VTREE_NOTLOADED_PURGECACHE, False);
-  end else if tab1 = tabData then begin
-    DataGrid.Tag := VTREE_NOTLOADED_PURGECACHE;
-    DataGrid.Invalidate;
-  end;
 end;
 
 
@@ -3188,8 +3176,7 @@ begin
     FreeAndNil(OldNumbers);
     FreeAndNil(Filters);
   end;
-  DataGrid.Tag := VTREE_NOTLOADED_PURGECACHE;
+  InvalidateVT(DataGrid, VTREE_NOTLOADED_PURGECACHE, False);
-  DataGrid.Invalidate;
 end;
 
 
@@ -3238,8 +3225,7 @@ end;
 procedure TMainForm.actRemoveFilterExecute(Sender: TObject);
 begin
   actClearFilterEditor.Execute;
-  DataGrid.Tag := VTREE_NOTLOADED_PURGECACHE;
+  InvalidateVT(DataGrid, VTREE_NOTLOADED_PURGECACHE, False);
-  DataGrid.Invalidate;
 end;
 
 
@@ -3362,8 +3348,7 @@ begin
   OldRowCount := DatagridWantedRowCount;
   Inc(DatagridWantedRowCount, prefGridRowcountStep);
   DataGridWantedRowCount := Min(DataGridWantedRowCount, prefGridRowcountMax);
-  DataGrid.Tag := VTREE_NOTLOADED;
+  InvalidateVT(DataGrid, VTREE_NOTLOADED, True);
-  DataGrid.Repaint;
   SelectNode(DataGrid, OldRowCount);
 end;
 
@@ -3372,8 +3357,7 @@ procedure TMainForm.actDataShowAllExecute(Sender: TObject);
 begin
   // Remove LIMIT clause
   DatagridWantedRowCount := prefGridRowcountMax;
-  DataGrid.Tag := VTREE_NOTLOADED;
+  InvalidateVT(DataGrid, VTREE_NOTLOADED, True);
-  DataGrid.Repaint;
 end;
 
 
@@ -3434,8 +3418,7 @@ begin
   while Assigned(Node) do begin
     if not DataGridRowHasFullData(Node) then begin
       DataGridFullRowMode := True;
-      Grid.Tag := VTREE_NOTLOADED_PURGECACHE;
+      InvalidateVT(Grid, VTREE_NOTLOADED_PURGECACHE, True);
-      Grid.Repaint;
       break;
     end;
     if SelectedOnly then
@@ -4088,8 +4071,7 @@ begin
       on E:Exception do
         MessageDlg(E.Message, mtError, [mbOK], 0);
     end;
-    ListProcesses.Tag := VTREE_NOTLOADED;
+    InvalidateVT(ListProcesses, VTREE_NOTLOADED, True);
-    ListProcesses.Repaint;
   end;
   TimerRefresh.Enabled := t; // re-enable autorefresh timer
 end;
@@ -6530,8 +6512,7 @@ begin
           // tab is a Host or Database tab, switch to showing table columns.
           if (PagecontrolMain.ActivePage = tabHost) or (PagecontrolMain.ActivePage = tabDatabase) then
             PagecontrolMain.ActivePage := tabEditor;
-          DataGrid.Tag := VTREE_NOTLOADED;
+          InvalidateVT(DataGrid, VTREE_NOTLOADED, False);
-          DataGrid.Invalidate;
           // When a table is clicked in the tree, and the query
           // tab is active, update the list of columns
           if QueryTabActive then
@@ -6548,8 +6529,7 @@ begin
     tabDatabase.Caption := sstr('Database: ' + newDb, 30);
     ListTables.ClearSelection;
     ListTables.FocusedNode := nil;
-    ListTables.Tag := VTREE_NOTLOADED;
+    InvalidateVT(ListTables, VTREE_NOTLOADED, False);
-    ListTables.Invalidate;
   end;
   PreviousFocusedNode := DBTree.FocusedNode;
   FixQueryTabCloseButtons;
@@ -6584,8 +6564,7 @@ begin
   SelectedTableColumns.Clear;
   SelectedTableKeys.Clear;
   SelectedTableForeignKeys.Clear;
-  DataGrid.Tag := VTREE_NOTLOADED_PURGECACHE;
+  InvalidateVT(DataGrid, VTREE_NOTLOADED_PURGECACHE, False);
-  DataGrid.Invalidate;
   try
     case SelectedTable.NodeType of
       lntTable: begin
@@ -6609,10 +6588,8 @@ end;
 
 procedure TMainForm.AfterClearDBObjects(Database: String);
 begin
-  if (Database='') or (ActiveDatabase=Database) then begin
+  if (Database='') or (ActiveDatabase=Database) then
-    ListTables.Tag := VTREE_NOTLOADED;
+    InvalidateVT(ListTables, VTREE_NOTLOADED, False);
-    ListTables.Invalidate;
-  end;
 end;
 
 
@@ -6988,8 +6965,7 @@ begin
       DataGridSortColumns[i].ColumnName := ColName;
       DataGridSortColumns[i].SortDirection := ORDER_ASC;
     end;
-    DataGrid.Tag := VTREE_NOTLOADED_PURGECACHE;
+    InvalidateVT(DataGrid, VTREE_NOTLOADED_PURGECACHE, False);
-    DataGrid.Invalidate;
   end else begin
     frm := TColumnSelectionForm.Create(self);
     // Position new form relative to btn's position
@@ -7359,8 +7335,7 @@ begin
         Raise Exception.Create('Server failed to insert row.');
       Result := True;
       GridFinalizeEditing(Sender);
-      DataGrid.Tag := VTREE_NOTLOADED_PURGECACHE;
+      InvalidateVT(DataGrid, VTREE_NOTLOADED_PURGECACHE, False);
-      DataGrid.Invalidate;
     except
       on E:Exception do begin
         MessageDlg(E.Message, mtError, [mbOK], 0);
@@ -7432,8 +7407,7 @@ begin
       Sender.EndUpdate;
     end else begin
       // Should never get called as we block DELETEs on tables without a unique key
-      DataGrid.Tag := VTREE_NOTLOADED_PURGECACHE;
+      InvalidateVT(DataGrid, VTREE_NOTLOADED_PURGECACHE, False);
-      DataGrid.Invalidate;
       msg := 'Warning: Consistency problem detected.' + CRLF + CRLF
         + 'The last DELETE query affected ' + FormatNumber(Affected) + ' rows, when it should have touched '+FormatNumber(Sender.SelectedCount)+' row(s)!'
         + CRLF + CRLF
@@ -9271,8 +9245,7 @@ end;
 procedure TMainForm.actDataResetSortingExecute(Sender: TObject);
 begin
   SetLength(DataGridSortColumns, 0);
-  DataGrid.Tag := VTREE_NOTLOADED_PURGECACHE;
+  InvalidateVT(DataGrid, VTREE_NOTLOADED_PURGECACHE, False);
-  DataGrid.Invalidate;
 end;
 
 
@@ -9311,8 +9284,7 @@ end;
 procedure TMainForm.actBlobAsTextExecute(Sender: TObject);
 begin
   // Activate displaying BLOBs as text data, ignoring possible weird effects in grid updates/inserts
-  DataGrid.Tag := VTREE_NOTLOADED_PURGECACHE;
+  InvalidateVT(DataGrid, VTREE_NOTLOADED_PURGECACHE, False);
-  DataGrid.Invalidate;
 end;