Pause background refreshes while driving a git operation

Several commands (rewording or amending an earlier commit, custom patch
operations, etc.) are implemented by starting an interactive rebase that stops
at a commit, amending it, and continuing. When no conflict occurs, the user
isn't meant to notice a rebase happened at all.

But a background file refresh can fire while the rebase is mid-flight and render
a dirty working copy of whatever the behind-the-scenes rebase is doing (e.g.
applying a custom patch).

To fix this, we pause the background routines for the duration of any
waiting-status operation — exactly the window in which lazygit is driving the
git operation itself and will refresh once at the end. The boundary is also
right for the conflict case: when a rebase stops on a conflict the operation
returns, the pause releases, and background refreshes resume for the interactive
resolution that follows.

Author: stefanhaller

pkg/gui/controllers/helpers/app_status_helper.go

@@ -66,12 +66,22 @@ func (self *AppStatusHelper) WithWaitingStatus(message string, f func(gocui.Task
 }
 
 func (self *AppStatusHelper) WithWaitingStatusImpl(message string, f func(gocui.Task) error, task gocui.Task) error {
+	// A waiting status means lazygit is driving a git operation itself (often
+	// one that internally runs a rebase and continues it). Pause the background
+	// routines for its duration so they don't refresh from an intermediate
+	// state and reveal, say, the half-finished history of a reword.
+	self.c.PauseBackgroundRefreshes(true)
+	defer self.c.PauseBackgroundRefreshes(false)
+
 	return self.statusMgr().WithWaitingStatus(message, self.renderAppStatus, func(waitingStatusHandle *status.WaitingStatusHandle) error {
 		return f(appStatusHelperTask{task, waitingStatusHandle})
 	})
 }
 
 func (self *AppStatusHelper) WithWaitingStatusSync(message string, f func() error) error {
+	self.c.PauseBackgroundRefreshes(true)
+	defer self.c.PauseBackgroundRefreshes(false)
+
 	return self.statusMgr().WithWaitingStatus(message, func() {}, func(*status.WaitingStatusHandle) error {
 		stop := make(chan struct{})
 		defer func() { close(stop) }()

pkg/gui/controllers/helpers/inline_status_helper.go

@@ -68,6 +68,14 @@ func (self *InlineStatusHelper) WithInlineStatus(opts InlineStatusOpts, f func(g
 	visible := view.Visible && self.windowHelper.TopViewInWindow(context.GetWindowName(), false) == view
 	if visible && context.IsItemVisible(opts.Item) {
 		self.c.OnWorker(func(task gocui.Task) error {
+			// An inline status is just a waiting status rendered on the item
+			// rather than in the bottom line, so it gets the same treatment:
+			// pause the background routines while we drive the operation. (The
+			// off-screen branch below goes through WithWaitingStatus, which
+			// already does this.)
+			self.c.PauseBackgroundRefreshes(true)
+			defer self.c.PauseBackgroundRefreshes(false)
+
 			self.start(opts)
 			defer self.stop(opts)
 

pkg/gui/gui_common.go

@@ -50,6 +50,10 @@ func (self *guiCommon) Resume() error {
 	return self.gui.resume()
 }
 
+func (self *guiCommon) PauseBackgroundRefreshes(pause bool) {
+	self.gui.BackgroundRoutineMgr.PauseBackgroundRefreshes(pause)
+}
+
 func (self *guiCommon) Context() types.IContextMgr {
 	return self.gui.State.ContextMgr
 }

pkg/gui/types/common.go

@@ -59,6 +59,10 @@ type IGuiCommon interface {
 	Suspend() error
 	Resume() error
 
+	// Pause or resume the background routines. Calls nest, so every pause must be balanced
+	// by a resume.
+	PauseBackgroundRefreshes(pause bool)
+
 	Context() IContextMgr
 	ContextForKey(key ContextKey) Context