From 6893d9a7590239c7a39aae3d2f3fd09a3e62f12d Mon Sep 17 00:00:00 2001 From: Stefan Haller Date: Wed, 8 Jul 2026 17:40:41 +0200 Subject: [PATCH] Add gocui primitives to block input during an operation Long-running operations that lazygit drives itself (rebases, and the commit surgery built on them) can be corrupted by keys the user presses while they run: pressing e to start an interactive rebase, then up+d before it finishes, must act on the resulting todo list, not race the rebase. WithWaitingStatusSync gets this today only as a side effect of freezing the UI thread, which the rest of this branch is moving away from. Add a nestable counter, BeginBlockingEvents/EndBlockingEvents, that withholds input at the event-dispatch layer without freezing anything: while blocked, key events are buffered and replayed in order once the count returns to zero (so they act on the now-current context), mouse clicks and hover are dropped (replaying them against a changed layout would target the wrong thing), and scrolling, resize, focus and all rendering keep flowing. These are the reusable core; a gui-level helper that brackets them around a worker operation follows. Co-Authored-By: Claude Opus 4.8 (1M context) --- pkg/gocui/block_events_test.go | 98 ++++++++++++++++++++++++++++++++++ pkg/gocui/gui.go | 73 +++++++++++++++++++++++++ 2 files changed, 171 insertions(+) create mode 100644 pkg/gocui/block_events_test.go diff --git a/pkg/gocui/block_events_test.go b/pkg/gocui/block_events_test.go new file mode 100644 index 000000000..277bac89a --- /dev/null +++ b/pkg/gocui/block_events_test.go @@ -0,0 +1,98 @@ +package gocui + +import ( + "testing" + + "github.com/stretchr/testify/assert" +) + +func TestEventWithheldWhileBlocking(t *testing.T) { + scenarios := []struct { + name string + event GocuiEvent + withheld bool + }{ + {"key", GocuiEvent{Type: eventKey, Key: NewKeyRune('x')}, true}, + {"mouse click", GocuiEvent{Type: eventMouse, Key: NewKeyName(MouseLeft)}, true}, + {"mouse scroll", GocuiEvent{Type: eventMouse, Key: NewKeyName(MouseWheelDown)}, false}, + {"mouse move", GocuiEvent{Type: eventMouseMove}, true}, + {"resize", GocuiEvent{Type: eventResize}, false}, + {"focus", GocuiEvent{Type: eventFocus}, false}, + {"paste", GocuiEvent{Type: eventPaste}, false}, + {"error", GocuiEvent{Type: eventError}, false}, + } + + for _, s := range scenarios { + t.Run(s.name, func(t *testing.T) { + assert.Equal(t, s.withheld, eventWithheldWhileBlocking(&s.event)) + }) + } +} + +// setupKeyRecorder wires a keybinding on a focused view that records each time +// it fires, and returns the key event that triggers it plus the record slice. +func setupKeyRecorder(t *testing.T, g *Gui) (GocuiEvent, *[]int) { + t.Helper() + + _, _ = g.SetView("main", 0, 0, 80, 22, 0) + _, err := g.SetCurrentView("main") + assert.NoError(t, err) + + fired := []int{} + callCount := 0 + key := NewKeyRune('x') + g.SetKeybinding("main", key, func(*Gui, *View) error { + callCount++ + fired = append(fired, callCount) + return nil + }) + + return GocuiEvent{Type: eventKey, Key: key}, &fired +} + +func TestBlockingEvents_KeysBufferedAndReplayed(t *testing.T) { + g := newTestGui(t) + keyEvent, fired := setupKeyRecorder(t, g) + + // Not blocking: the key dispatches immediately. + assert.NoError(t, g.handleEvent(&keyEvent)) + assert.Len(t, *fired, 1) + + // While blocking: the key is buffered, not dispatched. + g.BeginBlockingEvents() + assert.NoError(t, g.handleEvent(&keyEvent)) + assert.NoError(t, g.handleEvent(&keyEvent)) + assert.Len(t, *fired, 1, "buffered keys must not dispatch while blocking") + + // Unblocking replays the buffered keys. + assert.NoError(t, g.EndBlockingEvents()) + assert.Len(t, *fired, 3, "both buffered keys should replay on unblock") + assert.Empty(t, g.bufferedKeyEvents) +} + +func TestBlockingEvents_NestsWithCounter(t *testing.T) { + g := newTestGui(t) + keyEvent, fired := setupKeyRecorder(t, g) + + g.BeginBlockingEvents() + g.BeginBlockingEvents() + assert.NoError(t, g.handleEvent(&keyEvent)) + + // The inner block ending still leaves us blocked: no replay yet. + assert.NoError(t, g.EndBlockingEvents()) + assert.Empty(t, *fired) + + // Only the outermost block ending replays. + assert.NoError(t, g.EndBlockingEvents()) + assert.Len(t, *fired, 1) +} + +func TestBlockingEvents_MouseClicksDroppedNotBuffered(t *testing.T) { + g := newTestGui(t) + + g.BeginBlockingEvents() + click := GocuiEvent{Type: eventMouse, Key: NewKeyName(MouseLeft)} + assert.NoError(t, g.handleEvent(&click)) + assert.Empty(t, g.bufferedKeyEvents, "mouse clicks must be dropped, not buffered") + assert.NoError(t, g.EndBlockingEvents()) +} diff --git a/pkg/gocui/gui.go b/pkg/gocui/gui.go index 9da5225c0..700c2b54c 100644 --- a/pkg/gocui/gui.go +++ b/pkg/gocui/gui.go @@ -210,6 +210,14 @@ type Gui struct { // MainLoop starts. IsUIThread compares against it. Written once, read from // worker goroutines, so it's atomic. uiThreadID atomic.Int64 + + // blockInputCount, when greater than zero, withholds keyboard input from + // the handlers: key events are buffered into bufferedKeyEvents and replayed + // once the count drops back to zero, while mouse clicks and hover are + // dropped outright. It's a counter so blocking can nest. Both fields are + // only touched on the UI thread. See BeginBlockingEvents. + blockInputCount int + bufferedKeyEvents []GocuiEvent } type NewGuiOpts struct { @@ -806,6 +814,42 @@ func (g *Gui) IsUIThread() bool { return goid.Get() == g.uiThreadID.Load() } +// BeginBlockingEvents starts withholding keyboard input from the handlers, so a +// long-running operation can't be disrupted by keys the user presses while it +// runs. Keys are buffered and replayed once EndBlockingEvents balances this +// call; mouse clicks and hover are dropped for the duration. Scrolling, +// resizing, focus changes and all rendering keep working throughout. It's a +// counter, so blocking nests; every call must be paired with EndBlockingEvents. +// +// Must be called on the UI thread. Callers arrange this by beginning the block +// synchronously from the keybinding handler, before dispatching the operation +// to a worker — beginning it from the worker would race the next queued +// keypress, which is exactly the input we mean to withhold. +func (g *Gui) BeginBlockingEvents() { + g.blockInputCount++ +} + +// EndBlockingEvents balances a BeginBlockingEvents call. When the last nested +// block ends, the keys buffered while blocked are replayed in order through the +// normal dispatch path, so they act on the now-current context (a key whose +// binding no longer exists is simply ignored, just as if it had been pressed +// now). Must be called on the UI thread. +func (g *Gui) EndBlockingEvents() error { + g.blockInputCount-- + if g.blockInputCount > 0 { + return nil + } + + buffered := g.bufferedKeyEvents + g.bufferedKeyEvents = nil + for i := range buffered { + if err := g.handleEvent(&buffered[i]); err != nil { + return err + } + } + return nil +} + // OnUIThreadAndWait runs f on the main event-loop goroutine and blocks the // caller until f has run, returning f's error. Use it to read UI-thread-owned // state (the model, contexts) from a worker without racing the UI thread. @@ -1052,6 +1096,17 @@ func (g *Gui) processRemainingEvents() (bool, error) { // handleEvent handles an event, based on its type (key-press, error, // etc.) func (g *Gui) handleEvent(ev *GocuiEvent) error { + if g.blockInputCount > 0 && eventWithheldWhileBlocking(ev) { + if ev.Type == eventKey { + // Buffer keys so they replay against fresh state on unblock. + g.bufferedKeyEvents = append(g.bufferedKeyEvents, *ev) + } + // Mouse clicks and hover fall through to here without being buffered: + // replaying them once the operation has changed the layout underneath + // them would target the wrong thing, so we drop them outright. + return nil + } + switch ev.Type { case eventKey, eventMouse, eventMouseMove: return g.onKey(ev) @@ -1070,6 +1125,24 @@ func (g *Gui) handleEvent(ev *GocuiEvent) error { } } +// eventWithheldWhileBlocking reports whether an event must not reach the +// handlers while input is blocked (see BeginBlockingEvents). Key events are +// withheld (buffered for replay); mouse clicks and hover are withheld (dropped). +// Everything else — mouse scrolling, resize, focus, paste, errors — flows +// through as usual. +func eventWithheldWhileBlocking(ev *GocuiEvent) bool { + switch ev.Type { + case eventKey: + return true + case eventMouse: + return !IsMouseScrollKey(ev.Key.KeyName()) + case eventMouseMove: + return true + default: + return false + } +} + func (g *Gui) onResize() { // not sure if we actually need this // g.screen.Sync()