Issue #140: Store application process id in each tabs.ini section, and don't restore tabs from other running processes. If the process no longer runs, restore such tab sections again, so nothing gets lost with multiple running application instances.

source/apphelpers.pas

@@ -359,6 +359,7 @@ type
   function DpiScaleFactor(Form: TForm): Double;
   function GetThemeColor(Color: TColor): TColor;
   function ThemeIsDark(ThemeName: String): Boolean;
+  function ProcessExists(pid: Cardinal): Boolean;
 
 var
   AppSettings: TAppSettings;
@@ -3010,6 +3011,26 @@ begin
 end;
 
 
+function ProcessExists(pid: Cardinal): Boolean;
+var
+  Proc: TProcessEntry32;
+  SnapShot: THandle;
+  ContinueLoop: Boolean;
+begin
+  // Check if a given process id exists
+  SnapShot := CreateToolhelp32Snapshot(TH32CS_SnapProcess, 0);
+  Proc.dwSize := Sizeof(Proc);
+  Result := False;
+  ContinueLoop := Process32First(SnapShot, Proc);
+  while ContinueLoop do begin
+    Result := Proc.th32ProcessID = pid;
+    if Result then
+      Break;
+    ContinueLoop := Process32Next(SnapShot, Proc);
+  end;
+  CloseHandle(Snapshot);
+end;
+
 
 
 { Threading stuff }

source/main.pas

@@ -2173,11 +2173,13 @@ begin
       Section := Tab.Uid;
 
       if Tab.Memo.GetTextLen > 0 then begin
-        // Avoid writing the tabs.ini file through WriteString if nothing was effectively changed
+        // Avoid writing the tabs.ini file if nothing was effectively changed
         if TabsIni.ReadString(Section, 'BackupFilename', '') <> Tab.MemoBackupFilename then
           TabsIni.WriteString(Section, 'BackupFilename', Tab.MemoBackupFilename);
         if TabsIni.ReadString(Section, 'Filename', '') <> Tab.MemoFilename then
           TabsIni.WriteString(Section, 'Filename', Tab.MemoFilename);
+        if TabsIni.ReadInteger(Section, 'pid', 0) <> Integer(GetCurrentProcessId) then
+          TabsIni.WriteInteger(Section, 'pid', Integer(GetCurrentProcessId));
       end;
     end;
 
@@ -2197,6 +2199,7 @@ var
   Sections: TStringList;
   Section, Filename, BackupFilename: String;
   TabsIni: TIniFile;
+  pid: Cardinal;
 begin
   // Restore query tab setup from tabs.ini
 
@@ -2206,9 +2209,19 @@ begin
 
     Sections := TStringList.Create;
     TabsIni.ReadSections(Sections);
+
     for Section in Sections do begin
+
       Filename := TabsIni.ReadString(Section, 'Filename', '');
       BackupFilename := TabsIni.ReadString(Section, 'BackupFilename', '');
+      pid := Cardinal(TabsIni.ReadInteger(Section, 'pid', 0));
+
+      // Don't restore this tab if it belongs to a different running process
+      if (pid > 0) and (pid <> GetCurrentProcessId) and ProcessExists(pid) then
+        Continue;
+
+      // Either we have a backup file, or a user stored file.
+      // Both of them may not exist.
       if not BackupFilename.IsEmpty then begin
         if FileExists(BackupFilename) then begin
           Tab := ActiveOrEmptyQueryTab(False);
@@ -2217,7 +2230,7 @@ begin
           Tab.MemoFilename := Filename;
           Tab.Memo.Modified := True;
         end else begin
-          // Remove ini item if file is gone
+          // Remove tab section if backup file is gone or inaccessible for some reason
           TabsIni.EraseSection(Section);
         end;
       end else if not Filename.IsEmpty then begin
@@ -2227,11 +2240,13 @@ begin
           Tab.LoadContents(Filename, True, nil);
           Tab.MemoFilename := Filename;
         end else begin
-          // Remove ini item if file is gone
+          // Remove tab section if user stored file was deleted by user
           TabsIni.EraseSection(Section);
         end;
       end;
+
     end;
+
     Sections.Free;
     // Close file
     TabsIni.Free;