Elimination of unnecessary terminal flushes

ChangeLog

@@ -1,3 +1,6 @@
+2020-11-04  Markus Gans  <guru.mail@muenster.de>
+	* Elimination of unnecessary terminal flushes
+
 2020-11-03  Markus Gans  <guru.mail@muenster.de>
 	* Use FIONREAD to get the number of characters available 
 	  for reading on stdin

examples/mouse.cpp

@@ -521,6 +521,9 @@ void MouseDraw::drawCanvas()
   }
 
   printarea->has_changes = true;
+
+  if ( updateTerminal() )
+    flush();
 }
 
 //----------------------------------------------------------------------

src/fapplication.cpp

@@ -73,6 +73,7 @@ FMouseControl* FApplication::mouse           {nullptr};  // mouse control
 int            FApplication::loop_level      {0};        // event loop level
 int            FApplication::quit_code       {EXIT_SUCCESS};
 bool           FApplication::quit_now        {false};
+bool           FApplication::pending_updates {false};
 uInt64         FApplication::next_event_wait {5000};     // 5 ms (200 Hz)
 struct timeval FApplication::time_last_event {};
 
@@ -845,7 +846,6 @@ void FApplication::queuingKeyboardInput() const
   findKeyboardWidget();
   keyboard->escapeKeyHandling();  // special case: Esc key
   keyboard->clearKeyBufferOnTimeout();
-  std::fflush(stdout);
 
   if ( isKeyPressed() )
     keyboard->fetchKeyCode();
@@ -1234,11 +1234,18 @@ void FApplication::sendWheelEvent ( const FMouseData& md
 //----------------------------------------------------------------------
 inline void FApplication::flushTerminal()
 {
-  if ( flush_count == 0 || flush_count % 4 != 0 )
+  if ( ! pending_updates )
     return;
 
+  if ( flush_count < 4 )
+  {
+    flush_count++;
+    return;
+  }
+
   flush();
   flush_count = 0;
+  pending_updates = false;
 }
 
 //----------------------------------------------------------------------
@@ -1321,9 +1328,11 @@ bool FApplication::processNextEvent()
     processMouseEvent();
     processResizeEvent();
     processCloseWidget();
-    processTerminalUpdate();  // after terminal changes
+
+    if ( processTerminalUpdate() )  // after terminal changes
+      pending_updates = true;
+
     flushTerminal();
-    flush_count++;
     processLogger();
   }
 

src/fdialog.cpp

@@ -270,7 +270,9 @@ void FDialog::setPos (const FPoint& pos, bool)
   restoreOverlaidWindows();
   FWindow::adjustSize();
   setCursorToFocusWidget();
-  updateTerminal();
+
+  if ( updateTerminal() )
+    flush();
 }
 
 //----------------------------------------------------------------------

src/fkeyboard.cpp

@@ -467,15 +467,13 @@ FKey FKeyboard::UTF8decode (const char utf8[]) const
 //----------------------------------------------------------------------
 inline ssize_t FKeyboard::readKey()
 {
-  setNonBlockingInput();
   int len{0};
 
-  if ( ioctl(FTermios::getStdIn(), FIONREAD, &len) >= 0 && len > int(FIFO_BUF_SIZE) )
+  if ( ioctl(FTermios::getStdIn(), FIONREAD, &len) < 0 || len == 0 )
-    len = int(FIFO_BUF_SIZE);
+    return 0;
-  else
-    len = 1;
 
-  const ssize_t bytes = read(FTermios::getStdIn(), &read_character, std::size_t(len));
+  setNonBlockingInput();
+  const ssize_t bytes = read(FTermios::getStdIn(), &read_character, 1);
   unsetNonBlockingInput();
   return bytes;
 }
@@ -492,7 +490,7 @@ void FKeyboard::parseKeyBuffer()
 
     if ( bytesread + fifo_offset <= int(FIFO_BUF_SIZE) )
     {
-      fifo_buf[fifo_offset] = char(read_character);
+      fifo_buf[fifo_offset] = read_character;
       fifo_offset++;
       fifo_in_use = true;
     }
@@ -527,8 +525,6 @@ void FKeyboard::parseKeyBuffer()
     if ( fkey_queue.size() >= MAX_QUEUE_SIZE )
       break;
   }
-
-  read_character = 0;
 }
 
 //----------------------------------------------------------------------

src/flineedit.cpp

@@ -357,7 +357,9 @@ void FLineEdit::onKeyPress (FKeyEvent* ev)
     && key != fc::Fkey_enter )
   {
     drawInputField();
-    processTerminalUpdate();
+
+    if ( processTerminalUpdate() )
+      flush();
   }
 }
 
@@ -397,7 +399,9 @@ void FLineEdit::onMouseDown (FMouseEvent* ev)
       adjustTextOffset();
 
     drawInputField();
-    processTerminalUpdate();
+
+    if ( processTerminalUpdate() )
+      flush();
   }
 }
 
@@ -431,7 +435,9 @@ void FLineEdit::onMouseMove (FMouseEvent* ev)
 
     adjustTextOffset();
     drawInputField();
-    processTerminalUpdate();
+
+    if ( processTerminalUpdate() )
+      flush();
   }
 
   // auto-scrolling when dragging mouse outside the widget
@@ -534,7 +540,9 @@ void FLineEdit::onTimer (FTimerEvent*)
 
   adjustTextOffset();
   drawInputField();
-  processTerminalUpdate();
+
+  if ( processTerminalUpdate() )
+    flush();
 }
 
 //----------------------------------------------------------------------

src/flistbox.cpp

@@ -352,7 +352,8 @@ void FListBox::onMouseDown (FMouseEvent* ev)
     if ( yoffset_before != yoffset )
       vbar->drawBar();
 
-    processTerminalUpdate();
+    if ( processTerminalUpdate() )
+      flush();
   }
 }
 
@@ -425,7 +426,7 @@ void FListBox::onMouseMove (FMouseEvent* ev)
     if ( yoffset_before != yoffset )
       vbar->drawBar();
 
-    processTerminalUpdate();
+    if ( processTerminalUpdate() )
       flush();
   }
 
@@ -503,7 +504,8 @@ void FListBox::onTimer (FTimerEvent*)
   if ( yoffset_before != yoffset )
     vbar->drawBar();
 
-  processTerminalUpdate();
+  if ( processTerminalUpdate() )
+    flush();
 }
 
 //----------------------------------------------------------------------
@@ -545,7 +547,8 @@ void FListBox::onWheel (FWheelEvent* ev)
   if ( yoffset_before != yoffset )
     vbar->drawBar();
 
-  processTerminalUpdate();
+  if ( processTerminalUpdate() )
+    flush();
 }
 
 //----------------------------------------------------------------------
@@ -1079,7 +1082,8 @@ inline void FListBox::updateDrawing (bool draw_vbar, bool draw_hbar)
   if ( draw_hbar )
     hbar->drawBar();
 
-  processTerminalUpdate();
+  if ( processTerminalUpdate() )
+    flush();
 }
 
 //----------------------------------------------------------------------
@@ -1799,7 +1803,8 @@ void FListBox::cb_vbarChange (const FWidget*)
     if ( yoffset_before != yoffset )
       vbar->drawBar();
 
-    processTerminalUpdate();
+    if ( processTerminalUpdate() )
+      flush();
   }
 }
 
@@ -1867,7 +1872,8 @@ void FListBox::cb_hbarChange (const FWidget*)
     if ( xoffset_before != xoffset )
       hbar->drawBar();
 
-    processTerminalUpdate();
+    if ( processTerminalUpdate() )
+      flush();
   }
 }
 

src/flistview.cpp

@@ -1116,7 +1116,8 @@ void FListView::onMouseDown (FMouseEvent* ev)
       if ( first_line_position_before != first_visible_line.getPosition() )
         vbar->drawBar();
 
-      processTerminalUpdate();
+      if ( processTerminalUpdate() )
+        flush();
     }
   }
 }
@@ -1220,7 +1221,7 @@ void FListView::onMouseMove (FMouseEvent* ev)
     if ( first_line_position_before != first_visible_line.getPosition() )
       vbar->drawBar();
 
-    processTerminalUpdate();
+    if ( processTerminalUpdate() )
       flush();
   }
 
@@ -1307,7 +1308,8 @@ void FListView::onTimer (FTimerEvent*)
   if ( first_line_position_before != first_visible_line.getPosition() )
     vbar->drawBar();
 
-  processTerminalUpdate();
+  if ( processTerminalUpdate() )
+    flush();
 }
 
 //----------------------------------------------------------------------
@@ -1345,7 +1347,8 @@ void FListView::onWheel (FWheelEvent* ev)
   if ( first_line_position_before != first_visible_line.getPosition() )
     vbar->drawBar();
 
-  processTerminalUpdate();
+  if ( processTerminalUpdate() )
+    flush();
 }
 
 //----------------------------------------------------------------------
@@ -2149,7 +2152,8 @@ void FListView::updateDrawing (bool draw_vbar, bool draw_hbar)
   if ( draw_hbar )
     hbar->drawBar();
 
-  processTerminalUpdate();
+  if ( processTerminalUpdate() )
+    flush();
 }
 
 //----------------------------------------------------------------------
@@ -2868,7 +2872,8 @@ void FListView::cb_vbarChange (const FWidget*)
     if ( first_line_position_before != first_visible_line.getPosition() )
       vbar->drawBar();
 
-    processTerminalUpdate();
+    if ( processTerminalUpdate() )
+      flush();
   }
 }
 
@@ -2933,7 +2938,8 @@ void FListView::cb_hbarChange (const FWidget*)
     if ( xoffset_before != xoffset )
       hbar->drawBar();
 
-    processTerminalUpdate();
+    if ( processTerminalUpdate() )
+      flush();
   }
 }
 

src/fmenu.cpp

@@ -311,7 +311,8 @@ void FMenu::onMouseMove (FMouseEvent* ev)
   else if ( ms.hide_sub_menu )
   {
     closeOpenedSubMenu();
-    processTerminalUpdate();
+
+    if ( processTerminalUpdate() )
       flush();
   }
 }

src/fmenubar.cpp

@@ -223,8 +223,10 @@ void FMenuBar::onAccel (FAccelEvent* ev)
     getStatusBar()->drawMessage();
 
   redraw();
-  processTerminalUpdate();
+
+  if ( processTerminalUpdate() )
     flush();
+
   ev->accept();
 }
 
@@ -920,7 +922,8 @@ void FMenuBar::mouseMoveOverList (const FMouseEvent&& ev)
   if ( focus_changed )
   {
     redraw();
-    processTerminalUpdate();
+
+    if ( processTerminalUpdate() )
       flush();
   }
 }

src/fmenuitem.cpp

@@ -428,8 +428,9 @@ void FMenuItem::onAccel (FAccelEvent* ev)
     mbar->drop_down = false;
   }
 
-  processTerminalUpdate();
+  if ( processTerminalUpdate() )
     flush();
+
   ev->accept();
 }
 

src/fprogressbar.cpp

@@ -144,6 +144,7 @@ void FProgressbar::draw()
   if ( getFlags().shadow )
     drawShadow(this);
 
+  if ( processTerminalUpdate() )
     flush();
 }
 

src/fscrollbar.cpp

@@ -352,7 +352,10 @@ void FScrollbar::onMouseMove (FMouseEvent* ev)
     {
       setValue(new_val);
       drawBar();
-      processTerminalUpdate();
+
+      if ( processTerminalUpdate() )
+        flush();
+
       processScroll();
     }
   }
@@ -757,7 +760,10 @@ void FScrollbar::jumpToClickPos (int x, int y)
   {
     setValue(new_val);
     drawBar();
-    processTerminalUpdate();
+
+    if ( processTerminalUpdate() )
+      flush();
+
     scroll_type = FScrollbar::scrollJump;
     processScroll();
   }

src/fscrollview.cpp

@@ -411,7 +411,9 @@ void FScrollView::scrollTo (int x, int y)
 
   viewport->has_changes = true;
   copy2area();
-  processTerminalUpdate();
+
+  if ( processTerminalUpdate() )
+    flush();
 }
 
 //----------------------------------------------------------------------

src/ftextview.cpp

@@ -184,7 +184,9 @@ void FTextView::scrollTo (int x, int y)
   }
 
   drawText();
-  processTerminalUpdate();
+
+  if ( processTerminalUpdate() )
+    flush();
 }
 
 //----------------------------------------------------------------------
@@ -475,7 +477,8 @@ void FTextView::onWheel (FWheelEvent* ev)
   if ( isShown() )
     drawText();
 
-  processTerminalUpdate();
+  if ( processTerminalUpdate() )
+    flush();
 }
 
 //----------------------------------------------------------------------

src/fvterm.cpp

@@ -62,7 +62,7 @@ uInt                 FVTerm::clr_bol_length{};
 uInt                 FVTerm::clr_eol_length{};
 uInt                 FVTerm::cursor_address_length{};
 struct timeval       FVTerm::last_term_size_check{};
-std::queue<int>*     FVTerm::output_buffer{nullptr};
+std::vector<int>*    FVTerm::output_buffer{nullptr};
 FPoint*              FVTerm::term_pos{nullptr};
 const FVTerm*        FVTerm::init_object{nullptr};
 FSystem*             FVTerm::fsystem{nullptr};
@@ -266,7 +266,7 @@ void FVTerm::putVTerm() const
 }
 
 //----------------------------------------------------------------------
-void FVTerm::updateTerminal() const
+bool FVTerm::updateTerminal() const
 {
   // Updates pending changes to the terminal
 
@@ -275,7 +275,7 @@ void FVTerm::updateTerminal() const
   if ( no_terminal_updates || FApplication::isQuit()
     || ! (hasPendingUpdates(vterm) && draw_completed) )
   {
-    return;
+    return false;
   }
 
   std::size_t changedlines = 0;
@@ -287,12 +287,12 @@ void FVTerm::updateTerminal() const
       changedlines++;
 
     if ( changedlines % check_interval == 0
-      && (keyboard->hasUnprocessedInput() || keyboard->isKeyPressed(0))
+      && (keyboard->hasUnprocessedInput() || keyboard->isKeyPressed(0) )
       && skipped_terminal_update <= max_skip )
     {
       // Skipping terminal updates if there is unprocessed inputs
       skipped_terminal_update++;
-      return;
+      return false;
     }
   }
 
@@ -301,6 +301,7 @@ void FVTerm::updateTerminal() const
 
   // sets the new input cursor position
   updateTerminalCursor();
+  return changedlines > 0;
 }
 
 //----------------------------------------------------------------------
@@ -613,20 +614,18 @@ void FVTerm::flush()
 {
   // Flush the output buffer
 
-  if ( ! output_buffer )
+  if ( ! output_buffer || output_buffer->empty() )
     return;
 
-  while ( ! output_buffer->empty() )
-  {
   static const FTerm::defaultPutChar& FTermPutchar = FTerm::putchar();
 
-    if ( FTermPutchar )
+  if ( ! FTermPutchar )
-    {
+    return;
-      FTermPutchar (output_buffer->front());
-      output_buffer->pop();
-    }
-  }
 
+  for (auto&& ch : *output_buffer)
+    FTermPutchar(ch);
+
+  output_buffer->clear();
   std::fflush(stdout);
 }
 
@@ -1263,26 +1262,26 @@ void FVTerm::clearArea (FTermArea* area, int fillchar) const
 }
 
 //----------------------------------------------------------------------
-void FVTerm::processTerminalUpdate() const
+bool FVTerm::processTerminalUpdate() const
 {
   const auto& data = FTerm::getFTermData();
 
   // Checks if the resizing of the terminal is not finished
   if ( data && data->hasTermResized() )
-    return;
+    return false;
 
   // Monitor whether the terminal size has changed
   if ( isTermSizeChanged() )
   {
     raise (SIGWINCH);  // Send SIGWINCH
-    return;
+    return false;
   }
 
   // Update data on VTerm
   updateVTerm();
 
   // Update the visible terminal
-  updateTerminal();
+  return updateTerminal();
 }
 
 //----------------------------------------------------------------------
@@ -1845,7 +1844,7 @@ void FVTerm::init()
   {
     fterm         = new FTerm();
     term_pos      = new FPoint(-1, -1);
-    output_buffer = new std::queue<int>;
+    output_buffer = new std::vector<int>;
   }
   catch (const std::bad_alloc&)
   {
@@ -1857,6 +1856,9 @@ void FVTerm::init()
   // The final setting is made later in FTerm::init_locale().
   std::setlocale (LC_ALL, "");
 
+  // Reserve memory on the terminal output buffer
+  output_buffer->reserve(TERMINAL_OUTPUT_BUFFER_SIZE + 256);
+
   // term_attribute stores the current state of the terminal
   term_attribute.ch           = '\0';
   term_attribute.fg_color     = fc::Default;
@@ -3072,23 +3074,17 @@ inline void FVTerm::characterFilter (FChar& next_char)
 }
 
 //----------------------------------------------------------------------
-inline void FVTerm::appendOutputBuffer (const std::string& s)
+inline void FVTerm::appendOutputBuffer (const std::string& str)
 {
-  const auto& c_string = s.c_str();
+  for (auto&& ch : str)
-  FTermcap::paddingPrint (c_string, 1, appendOutputBuffer);
+    FVTerm::appendOutputBuffer(int(ch));
-}
-
-//----------------------------------------------------------------------
-inline void FVTerm::appendOutputBuffer (const char s[])
-{
-  FTermcap::paddingPrint (s, 1, appendOutputBuffer);
 }
 
 //----------------------------------------------------------------------
 int FVTerm::appendOutputBuffer (int ch)
 {
   // append method for unicode character
-  output_buffer->push(ch);
+  output_buffer->push_back(ch);
 
   if ( output_buffer->size() >= TERMINAL_OUTPUT_BUFFER_SIZE )
     flush();

src/fwidget.cpp

@@ -981,8 +981,10 @@ void FWidget::show()
   if ( show_root_widget && show_root_widget == this )
   {
     finishDrawing();
-    processTerminalUpdate();
+
+    if ( processTerminalUpdate() )
       flush();
+
     show_root_widget = nullptr;
   }
 

src/include/final/fapplication.h

@@ -243,10 +243,10 @@ class FApplication : public FWidget
     int                   flush_count{0};
     static uInt64         next_event_wait;
     static timeval        time_last_event;
+    static int            loop_level;
     static int            quit_code;
     static bool           quit_now;
-    static int            loop_level;
+    static bool           pending_updates;
-    static bool           process_timer_event;
     static FMouseControl* mouse;
     static FKeyboard*     keyboard;
     static FWidget*       keyboard_widget;

src/include/final/fkeyboard.h

@@ -197,7 +197,7 @@ class FKeyboard final
     std::queue<FKey>      fkey_queue{};
     FKey                  fkey{0};
     FKey                  key{0};
-    uChar                 read_character{};
+    char                  read_character{};
     char                  fifo_buf[FIFO_BUF_SIZE]{'\0'};
     int                   fifo_offset{0};
     int                   stdin_status_flags{0};

src/include/final/fvterm.h

@@ -50,7 +50,6 @@
 
 #include <sys/time.h>  // need for timeval (cygwin)
 
-#include <queue>
 #include <string>
 #include <utility>
 #include <vector>
@@ -255,7 +254,7 @@ class FVTerm
     void                  createVTerm (const FSize&);
     void                  resizeVTerm (const FSize&) const;
     void                  putVTerm() const;
-    void                  updateTerminal() const;
+    bool                  updateTerminal() const;
     virtual void          addPreprocessingHandler ( const FVTerm*
                                                   , const FPreprocessingFunction& );
     virtual void          delPreprocessingHandler (const FVTerm*);
@@ -318,7 +317,7 @@ class FVTerm
     void                  scrollAreaForward (FTermArea*) const;
     void                  scrollAreaReverse (FTermArea*) const;
     void                  clearArea (FTermArea*, int = ' ') const;
-    void                  processTerminalUpdate() const;
+    bool                  processTerminalUpdate() const;
     static void           startDrawing();
     static void           finishDrawing();
     virtual void          initTerminal();
@@ -420,7 +419,8 @@ class FVTerm
     void                  appendLowerRight (FChar&) const;
     static void           characterFilter (FChar&);
     static void           appendOutputBuffer (const std::string&);
-    static void           appendOutputBuffer (const char[]);
+    template <std::size_t N>
+    static void           appendOutputBuffer (const char (&)[N]);
     static int            appendOutputBuffer (int);
 
     // Data members
@@ -433,7 +433,7 @@ class FVTerm
     static FTermArea*        vterm;        // virtual terminal
     static FTermArea*        vdesktop;     // virtual desktop
     static FTermArea*        active_area;  // active area
-    static std::queue<int>* output_buffer;
+    static std::vector<int>* output_buffer;
     static FChar             term_attribute;
     static FChar             next_attribute;
     static FChar             s_ch;      // shadow character
@@ -988,6 +988,14 @@ inline bool FVTerm::isCursorHideable() const
 inline void FVTerm::hideVTermCursor() const
 { vterm->input_cursor_visible = false; }
 
+//----------------------------------------------------------------------
+template <std::size_t N>
+inline void FVTerm::appendOutputBuffer (const char (&str)[N])
+{
+  for (auto&& ch : str)
+    FVTerm::appendOutputBuffer(int(ch));
+}
+
 }  // namespace finalcut
 
 #endif  // FVTERM_H