vim-patch:8.1.0822: peeking and flushing output slows down execution

Problem:    Peeking and flushing output slows down execution.
Solution:   Do not update the mode message when global_busy is set.  Do not
            flush when only peeking for a character. (Ken Takata)
cb574f4154

src/nvim/edit.c

@@ -7803,7 +7803,7 @@ static bool ins_esc(long *count, int cmdchar, bool nomove)
   // Otherwise remove the mode message.
   if (reg_recording != 0 || restart_edit != NUL) {
     showmode();
-  } else if (p_smd) {
+  } else if (p_smd && !skip_showmode()) {
     MSG("");
   }
   // Exit Insert mode

src/nvim/getchar.c

@@ -2490,8 +2490,10 @@ int inchar(
     }
 
     // Always flush the output characters when getting input characters
-    // from the user.
+    // from the user and not just peeking.
-    ui_flush();
+    if (wait_time == -1L || wait_time > 10L) {
+      ui_flush();
+    }
 
     // Fill up to a third of the buffer, because each character may be
     // tripled below.

src/nvim/screen.c

@@ -6557,6 +6557,21 @@ void grid_del_lines(ScreenGrid *grid, int row, int line_count, int end, int col,
   return;
 }
 
+// Return true when postponing displaying the mode message: when not redrawing
+// or inside a mapping.
+bool skip_showmode(void)
+{
+  // Call char_avail() only when we are going to show something, because it
+  // takes a bit of time.  redrawing() may also call char_avail_avail().
+  if (global_busy
+      || msg_silent != 0
+      || !redrawing()
+      || (char_avail() && !KeyTyped)) {
+    redraw_cmdline = true;  // show mode later
+    return true;
+  }
+  return false;
+}
 
 // Show the current mode and ruler.
 //
@@ -6588,12 +6603,8 @@ int showmode(void)
                  || restart_edit
                  || VIsual_active));
   if (do_mode || reg_recording != 0) {
-    // Don't show mode right now, when not redrawing or inside a mapping.
+    if (skip_showmode()) {
-    // Call char_avail() only when we are going to show something, because
+      return 0;  // show mode later
-    // it takes a bit of time.
-    if (!redrawing() || (char_avail() && !KeyTyped) || msg_silent != 0) {
-      redraw_cmdline = TRUE;                    /* show mode later */
-      return 0;
     }
 
     nwr_save = need_wait_return;

test/functional/eval/null_spec.lua

@@ -121,7 +121,7 @@ describe('NULL', function()
     null_test('does not make Neovim crash when v:oldfiles gets assigned to that', ':let v:oldfiles = L|oldfiles', 0)
     null_expr_test('does not make complete() crash or error out',
                    'execute(":normal i\\<C-r>=complete(1, L)[-1]\\n")',
-                   '', '\n', function()
+                   0, '', function()
       eq({''}, curbufmeths.get_lines(0, -1, false))
     end)
     null_expr_test('is accepted by setmatches()', 'setmatches(L)', 0, 0)

test/functional/eval/timer_spec.lua

@@ -130,12 +130,12 @@ describe('timers', function()
     nvim_async("command", "call timer_start("..load_adjust(100)..", 'AddItem', {'repeat': -1})")
 
     screen:expect([[
-      ITEM 1                                  |
+      ^ITEM 1                                  |
       ITEM 2                                  |
       {1:~                                       }|
       {1:~                                       }|
       {1:~                                       }|
-      ^                                        |
+                                              |
     ]])
     nvim_async("command", "let g:cont = 1")
 

test/functional/terminal/tui_spec.lua

@@ -391,7 +391,7 @@ describe('TUI', function()
       {1:x}                                                 |
       {4:~                                                 }|
       {5:[No Name] [+]                   3,1            All}|
-                                                        |
+      :set ruler                                        |
       {3:-- TERMINAL --}                                    |
     ]]
     local expected_attr = {

test/functional/ui/screen.lua

@@ -807,7 +807,9 @@ function Screen:_handle_mouse_off()
 end
 
 function Screen:_handle_mode_change(mode, idx)
-  assert(mode == self._mode_info[idx+1].name)
+  if self._mode_info ~= nil then
+    assert(mode == self._mode_info[idx+1].name)
+  end
   self.mode = mode
 end