Fix race condition where preview window is not properly cleared

2 files changed, 28 insertions, 17 deletions

diff --git a/src/terminal.go b/src/terminal.go
index 18d5f0c5..213d3b06 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -82,6 +82,11 @@ type selectedItem struct {
 
 type byTimeOrder []selectedItem
 
+type previewRequest struct {
+	ok  bool
+	str string
+}
+
 func (a byTimeOrder) Len() int {
 	return len(a)
 }
@@ -908,21 +913,23 @@ func (t *Terminal) Loop() {
 	if t.hasPreviewWindow() {
 		go func() {
 			for {
-				focused := ""
+				request := previewRequest{false, ""}
 				t.previewBox.Wait(func(events *util.Events) {
 					for req, value := range *events {
 						switch req {
 						case reqPreviewEnqueue:
-							focused = value.(string)
+							request = value.(previewRequest)
 						}
 					}
 					events.Clear()
 				})
-				if len(focused) > 0 {
-					command := strings.Replace(t.preview.command, "{}", quoteEntry(focused), -1)
+				if request.ok {
+					command := strings.Replace(t.preview.command, "{}", quoteEntry(request.str), -1)
 					cmd := util.ExecCommand(command)
 					out, _ := cmd.CombinedOutput()
 					t.reqBox.Set(reqPreviewDisplay, string(out))
+				} else {
+					t.reqBox.Set(reqPreviewDisplay, "")
 				}
 			}
 		}()
@@ -936,7 +943,7 @@ func (t *Terminal) Loop() {
 	}
 
 	go func() {
-		focused := ""
+		focused := previewRequest{false, ""}
 		for {
 			t.reqBox.Wait(func(events *util.Events) {
 				defer events.Clear()
@@ -953,19 +960,17 @@ func (t *Terminal) Loop() {
 					case reqList:
 						t.printList()
 						cnt := t.merger.Length()
+						var currentFocus previewRequest
 						if cnt > 0 && cnt > t.cy {
-							currentFocus := t.current()
-							if currentFocus != focused {
-								focused = currentFocus
-								if t.isPreviewEnabled() {
-									t.previewBox.Set(reqPreviewEnqueue, focused)
-								}
-							}
+							currentFocus = previewRequest{true, t.current()}
 						} else {
-							if focused != "" && t.isPreviewEnabled() {
-								t.pwindow.Erase()
+							currentFocus = previewRequest{false, ""}
+						}
+						if currentFocus != focused {
+							focused = currentFocus
+							if t.isPreviewEnabled() {
+								t.previewBox.Set(reqPreviewEnqueue, focused)
 							}
-							focused = ""
 						}
 					case reqJump:
 						if t.merger.Length() == 0 {
@@ -1076,7 +1081,7 @@ func (t *Terminal) Loop() {
 					t.resizeWindows()
 					cnt := t.merger.Length()
 					if t.previewing && cnt > 0 && cnt > t.cy {
-						t.previewBox.Set(reqPreviewEnqueue, t.current())
+						t.previewBox.Set(reqPreviewEnqueue, previewRequest{true, t.current()})
 					}
 					req(reqList, reqInfo)
 				}
diff --git a/test/test_go.rb b/test/test_go.rb
index a6d67190..c375fac1 100644
--- a/test/test_go.rb
+++ b/test/test_go.rb
@@ -1229,14 +1229,20 @@ class TestGoFZF < TestBase
   end
 
   def test_preview
-    tmux.send_keys %[seq 1000 | #{FZF} --preview 'echo {{}-{}}' --bind ?:toggle-preview], :Enter
+    tmux.send_keys %[seq 1000 | sed s/^2$// | #{FZF} --preview 'sleep 0.2; echo {{}-{}}' --bind ?:toggle-preview], :Enter
     tmux.until { |lines| lines[1].include?(' {1-1}') }
+    tmux.send_keys :Up
+    tmux.until { |lines| lines[1].include?(' {-}') }
     tmux.send_keys '555'
     tmux.until { |lines| lines[1].include?(' {555-555}') }
     tmux.send_keys '?'
     tmux.until { |lines| !lines[1].include?(' {555-555}') }
     tmux.send_keys '?'
     tmux.until { |lines| lines[1].include?(' {555-555}') }
+    tmux.send_keys :BSpace
+    tmux.until { |lines| lines[-2].start_with? '  28/1000' }
+    tmux.send_keys 'foobar'
+    tmux.until { |lines| !lines[1].include?('{') }
   end
 
   def test_preview_hidden