[ruby/reline] Implement buffered output to Reline::ANSI

(ruby/reline#790)

Minimize the call of STDOUT.write
This will improve rendering performance especially when there is a busy thread `Thread.new{loop{}}`

ruby/reline@a6fe45f5ba

Author: tompng

lib/reline.rb

@@ -181,9 +181,7 @@ def input=(val)
     def output=(val)
       raise TypeError unless val.respond_to?(:write) or val.nil?
       @output = val
-      if io_gate.respond_to?(:output=)
-        io_gate.output = val
-      end
+      io_gate.output = val
     end
 
     def vi_editing_mode
@@ -317,7 +315,6 @@ def readline(prompt = '', add_hist = false)
       else
         line_editor.multiline_off
       end
-      line_editor.output = output
       line_editor.completion_proc = completion_proc
       line_editor.completion_append_character = completion_append_character
       line_editor.output_modifier_proc = output_modifier_proc

lib/reline/io/ansi.rb

@@ -29,10 +29,13 @@ class Reline::ANSI < Reline::IO
     'H' => [:ed_move_to_beg, {}],
   }
 
+  attr_writer :input, :output
+
   def initialize
     @input = STDIN
     @output = STDOUT
     @buf = []
+    @output_buffer = nil
     @old_winch_handler = nil
   end
 
@@ -114,14 +117,6 @@ def set_default_key_bindings_comprehensive_list(config)
     end
   end
 
-  def input=(val)
-    @input = val
-  end
-
-  def output=(val)
-    @output = val
-  end
-
   def with_raw_input
     if @input.tty?
       @input.raw(intr: true) { yield }
@@ -238,49 +233,65 @@ def both_tty?
     @input.tty? && @output.tty?
   end
 
+  def write(string)
+    if @output_buffer
+      @output_buffer << string
+    else
+      @output.write(string)
+    end
+  end
+
+  def buffered_output
+    @output_buffer = +''
+    yield
+    @output.write(@output_buffer)
+  ensure
+    @output_buffer = nil
+  end
+
   def move_cursor_column(x)
-    @output.write "\e[#{x + 1}G"
+    write "\e[#{x + 1}G"
   end
 
   def move_cursor_up(x)
     if x > 0
-      @output.write "\e[#{x}A"
+      write "\e[#{x}A"
     elsif x < 0
       move_cursor_down(-x)
     end
   end
 
   def move_cursor_down(x)
     if x > 0
-      @output.write "\e[#{x}B"
+      write "\e[#{x}B"
     elsif x < 0
       move_cursor_up(-x)
     end
   end
 
   def hide_cursor
-    @output.write "\e[?25l"
+    write "\e[?25l"
   end
 
   def show_cursor
-    @output.write "\e[?25h"
+    write "\e[?25h"
   end
 
   def erase_after_cursor
-    @output.write "\e[K"
+    write "\e[K"
   end
 
   # This only works when the cursor is at the bottom of the scroll range
   # For more details, see https://github.com/ruby/reline/pull/577#issuecomment-1646679623
   def scroll_down(x)
     return if x.zero?
     # We use `\n` instead of CSI + S because CSI + S would cause https://github.com/ruby/reline/issues/576
-    @output.write "\n" * x
+    write "\n" * x
   end
 
   def clear_screen
-    @output.write "\e[2J"
-    @output.write "\e[1;1H"
+    write "\e[2J"
+    write "\e[1;1H"
   end
 
   def set_winch_handler(&handler)
@@ -300,14 +311,14 @@ def set_winch_handler(&handler)
 
   def prep
     # Enable bracketed paste
-    @output.write "\e[?2004h" if Reline.core.config.enable_bracketed_paste && both_tty?
+    write "\e[?2004h" if Reline.core.config.enable_bracketed_paste && both_tty?
     retrieve_keybuffer
     nil
   end
 
   def deprep(otio)
     # Disable bracketed paste
-    @output.write "\e[?2004l" if Reline.core.config.enable_bracketed_paste && both_tty?
+    write "\e[?2004l" if Reline.core.config.enable_bracketed_paste && both_tty?
     Signal.trap('WINCH', @old_winch_handler) if @old_winch_handler
     Signal.trap('CONT', @old_cont_handler) if @old_cont_handler
   end

lib/reline/io/dumb.rb

@@ -3,8 +3,11 @@
 class Reline::Dumb < Reline::IO
   RESET_COLOR = '' # Do not send color reset sequence
 
+  attr_writer :output
+
   def initialize(encoding: nil)
     @input = STDIN
+    @output = STDOUT
     @buf = []
     @pasting = false
     @encoding = encoding
@@ -39,6 +42,14 @@ def with_raw_input
     yield
   end
 
+  def write(string)
+    @output.write(string)
+  end
+
+  def buffered_output
+    yield
+  end
+
   def getc(_timeout_second)
     unless @buf.empty?
       return @buf.shift

lib/reline/io/windows.rb

@@ -1,6 +1,9 @@
 require 'fiddle/import'
 
 class Reline::Windows < Reline::IO
+
+  attr_writer :output
+
   def initialize
     @input_buf = []
     @output_buf = []
@@ -308,6 +311,14 @@ def with_raw_input
     yield
   end
 
+  def write(string)
+    @output.write(string)
+  end
+
+  def buffered_output
+    yield
+  end
+
   def getc(_timeout_second)
     check_input_event
     @output_buf.shift

lib/reline/line_editor.rb

@@ -13,7 +13,6 @@ class Reline::LineEditor
   attr_accessor :prompt_proc
   attr_accessor :auto_indent_proc
   attr_accessor :dig_perfect_match_proc
-  attr_writer :output
 
   VI_MOTIONS = %i{
     ed_prev_char
@@ -414,7 +413,7 @@ def render_line_differential(old_items, new_items)
         # do nothing
       elsif level == :blank
         Reline::IOGate.move_cursor_column base_x
-        @output.write "#{Reline::IOGate.reset_color_sequence}#{' ' * width}"
+        Reline::IOGate.write "#{Reline::IOGate.reset_color_sequence}#{' ' * width}"
       else
         x, w, content = new_items[level]
         cover_begin = base_x != 0 && new_levels[base_x - 1] == level
@@ -424,7 +423,7 @@ def render_line_differential(old_items, new_items)
           content, pos = Reline::Unicode.take_mbchar_range(content, base_x - x, width, cover_begin: cover_begin, cover_end: cover_end, padding: true)
         end
         Reline::IOGate.move_cursor_column x + pos
-        @output.write "#{Reline::IOGate.reset_color_sequence}#{content}#{Reline::IOGate.reset_color_sequence}"
+        Reline::IOGate.write "#{Reline::IOGate.reset_color_sequence}#{content}#{Reline::IOGate.reset_color_sequence}"
       end
       base_x += width
     end
@@ -460,19 +459,21 @@ def update_dialogs(key = nil)
   end
 
   def render_finished
-    render_differential([], 0, 0)
-    lines = @buffer_of_lines.size.times.map do |i|
-      line = Reline::Unicode.strip_non_printing_start_end(prompt_list[i]) + modified_lines[i]
-      wrapped_lines = split_line_by_width(line, screen_width)
-      wrapped_lines.last.empty? ? "#{line} " : line
+    Reline::IOGate.buffered_output do
+      render_differential([], 0, 0)
+      lines = @buffer_of_lines.size.times.map do |i|
+        line = Reline::Unicode.strip_non_printing_start_end(prompt_list[i]) + modified_lines[i]
+        wrapped_lines = split_line_by_width(line, screen_width)
+        wrapped_lines.last.empty? ? "#{line} " : line
+      end
+      Reline::IOGate.write lines.map { |l| "#{l}\r\n" }.join
     end
-    @output.puts lines.map { |l| "#{l}\r\n" }.join
   end
 
   def print_nomultiline_prompt
     Reline::IOGate.disable_auto_linewrap(true) if Reline::IOGate.win?
     # Readline's test `TestRelineAsReadline#test_readline` requires first output to be prompt, not cursor reset escape sequence.
-    @output.write Reline::Unicode.strip_non_printing_start_end(@prompt) if @prompt && !@is_multiline
+    Reline::IOGate.write Reline::Unicode.strip_non_printing_start_end(@prompt) if @prompt && !@is_multiline
   ensure
     Reline::IOGate.disable_auto_linewrap(false) if Reline::IOGate.win?
   end
@@ -503,7 +504,9 @@ def render
       end
     end
 
-    render_differential new_lines, wrapped_cursor_x, wrapped_cursor_y - screen_scroll_top
+    Reline::IOGate.buffered_output do
+      render_differential new_lines, wrapped_cursor_x, wrapped_cursor_y - screen_scroll_top
+    end
   end
 
   # Reflects lines to be rendered and new cursor position to the screen

test/reline/test_line_editor.rb

@@ -61,6 +61,10 @@ def test_retrieve_completion_quote
 
   class RenderLineDifferentialTest < Reline::TestCase
     class TestIO < Reline::IO
+      def write(string)
+        @output << string
+      end
+
       def move_cursor_column(col)
         @output << "[COL_#{col}]"
       end
@@ -76,7 +80,6 @@ def setup
       @original_iogate = Reline::IOGate
       @output = StringIO.new
       @line_editor.instance_variable_set(:@screen_size, [24, 80])
-      @line_editor.instance_variable_set(:@output, @output)
       Reline.send(:remove_const, :IOGate)
       Reline.const_set(:IOGate, TestIO.new)
       Reline::IOGate.instance_variable_set(:@output, @output)

test/reline/test_macro.rb

@@ -6,7 +6,7 @@ def setup
     @config = Reline::Config.new
     @encoding = Reline.core.encoding
     @line_editor = Reline::LineEditor.new(@config)
-    @output = @line_editor.output = File.open(IO::NULL, "w")
+    @output = Reline::IOGate.output = File.open(IO::NULL, "w")
   end
 
   def teardown