Avoid enumerating untracked files when staging hunks of tracked files

We know that staging or unstaging a hunk in a tracked file doesn't have
influence on untracked files, so we can take them over from the previous state
of the model. This can be a performance improvement in repos with many untracked
files.

Author: stefanhaller

pkg/gui/controllers/helpers/refresh_helper.go

@@ -169,7 +169,7 @@ func (self *RefreshHelper) Refresh(options types.RefreshOptions) {
 		if scopeSet.Includes(types.FILES) || scopeSet.Includes(types.SUBMODULES) {
 			fileWg.Add(1)
 			refresh("files", func() {
-				_ = self.refreshFilesAndSubmodules()
+				_ = self.refreshFilesAndSubmodules(options.TakeOverUntrackedFilesFromPreviousModel)
 				fileWg.Done()
 			})
 		}
@@ -539,7 +539,7 @@ func (self *RefreshHelper) refreshBranches(refreshWorktrees bool, keepBranchSele
 	self.refreshStatus()
 }
 
-func (self *RefreshHelper) refreshFilesAndSubmodules() error {
+func (self *RefreshHelper) refreshFilesAndSubmodules(takeOverUntrackedFilesFromPreviousModel bool) error {
 	self.c.Mutexes().RefreshingFilesMutex.Lock()
 	self.c.State().SetIsRefreshingFiles(true)
 	defer func() {
@@ -551,7 +551,7 @@ func (self *RefreshHelper) refreshFilesAndSubmodules() error {
 		return err
 	}
 
-	if err := self.refreshStateFiles(); err != nil {
+	if err := self.refreshStateFiles(takeOverUntrackedFilesFromPreviousModel); err != nil {
 		return err
 	}
 
@@ -564,7 +564,7 @@ func (self *RefreshHelper) refreshFilesAndSubmodules() error {
 	return nil
 }
 
-func (self *RefreshHelper) refreshStateFiles() error {
+func (self *RefreshHelper) refreshStateFiles(takeOverUntrackedFilesFromPreviousModel bool) error {
 	fileTreeViewModel := self.c.Contexts().Files.FileTreeViewModel
 
 	prevConflictFileCount := 0
@@ -599,15 +599,27 @@ func (self *RefreshHelper) refreshStateFiles() error {
 		}
 	}
 
+	var previousUntrackedFiles []*models.File
+	if takeOverUntrackedFilesFromPreviousModel {
+		previousUntrackedFiles = lo.Filter(self.c.Model().Files,
+			func(file *models.File, _ int) bool { return file.ShortStatus == "??" })
+	}
+
 	showUntracked := git_commands.ShowUntrackedModeAuto
-	if self.c.Contexts().Files.ForceShowUntracked() {
+	if takeOverUntrackedFilesFromPreviousModel {
+		showUntracked = git_commands.ShowUntrackedModeOff
+	} else if self.c.Contexts().Files.ForceShowUntracked() {
 		showUntracked = git_commands.ShowUntrackedModeOn
 	}
 	files := self.c.Git().Loaders.FileLoader.
 		GetStatusFiles(git_commands.GetStatusFileOptions{
 			ShowUntracked: showUntracked,
 		})
 
+	if takeOverUntrackedFilesFromPreviousModel {
+		files = append(files, previousUntrackedFiles...)
+	}
+
 	conflictFileCount := 0
 	for _, file := range files {
 		if file.HasMergeConflicts {

pkg/gui/controllers/staging_controller.go

@@ -226,11 +226,16 @@ func (self *StagingController) DiscardSelection() error {
 }
 
 func (self *StagingController) applySelectionAndRefresh(reverse bool) error {
+	isTracked := self.c.Contexts().Files.GetSelectedFile().Tracked
+
 	if err := self.applySelection(reverse); err != nil {
 		return err
 	}
 
-	self.c.Refresh(types.RefreshOptions{Scope: []types.RefreshableView{types.FILES, types.STAGING}})
+	self.c.Refresh(types.RefreshOptions{
+		Scope:                                   []types.RefreshableView{types.FILES, types.STAGING},
+		TakeOverUntrackedFilesFromPreviousModel: isTracked,
+	})
 	return nil
 }
 
@@ -281,11 +286,16 @@ func (self *StagingController) applySelection(reverse bool) error {
 }
 
 func (self *StagingController) EditHunkAndRefresh() error {
+	isTracked := self.c.Contexts().Files.GetSelectedFile().Tracked
+
 	if err := self.editHunk(); err != nil {
 		return err
 	}
 
-	self.c.Refresh(types.RefreshOptions{Scope: []types.RefreshableView{types.FILES, types.STAGING}})
+	self.c.Refresh(types.RefreshOptions{
+		Scope:                                   []types.RefreshableView{types.FILES, types.STAGING},
+		TakeOverUntrackedFilesFromPreviousModel: isTracked,
+	})
 	return nil
 }
 

pkg/gui/types/refresh.go

@@ -44,4 +44,9 @@ type RefreshOptions struct {
 	// keeps the selection index the same. Useful after checking out a detached
 	// head, and selecting index 0.
 	KeepBranchSelectionIndex bool
+
+	// If true, call git status with --untracked-files=no to skip enumerating untracked files, and
+	// keep the ones we have in the model. Useful as a performance optimization when we know the
+	// untracked files can't have changed, e.g. after staging/unstaging hunks of tracked files.
+	TakeOverUntrackedFilesFromPreviousModel bool
 }