Debounce key-presses to improve responsiveness

This idea is based on a patch from Yiding Jia, with some additional
logic added to ensure that potentially expensive matching only occurs
when really needed (ie. we don't re-match just because you hit a cursor
up or down key).

Not sure what the sweet spot for the debounce interval is, so starting
with 50ms, and making it configurable. I suspect that on really large
hierarchies you might want this to be higher (say, 100, 150 or even
200ms) in order to reduce the likelihood of unwanted match computations
kicking off just because you happened to slow a little in typing.

Note the use of augroups here to ensure that we don't keep adding more
and more autocmds to the buffer (depending on the platform, the buffer
will be cleaned up with bwipeout! or bunload!; in practice the same
buffer is usually used over and over again, so we wind up with a single
autocmd assigned to a buffer designated as `<buffer=2>` or similar).

Signed-off-by: Wincent Colaiuta <win@wincent.com>

LICENSE

@@ -1,4 +1,4 @@
-Copyright 2010-2012 Wincent Colaiuta. All rights reserved.
+Copyright 2010-2014 Wincent Colaiuta. All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:

doc/command-t.txt

@@ -477,6 +477,14 @@ Following is a list of all available options:
       If set to 0, the window will occupy as much of the available space as
       needed to show matching entries.
 
+                                               *g:CommandTInputDebounce*
+  |g:CommandTInputDebounce|                      number (default: 50)
+
+      The number of milliseconds to wait before updating the match listing
+      following a key-press. This can be used to avoid wasteful recomputation
+      when making a rapid series of key-presses in a directory with many tens
+      (or hundreds) of thousands of files.
+
                                                *g:CommandTMinHeight*
   |g:CommandTMinHeight|                          number (default: 0)
 
@@ -677,16 +685,16 @@ Command-T is written and maintained by Wincent Colaiuta <win@wincent.com>.
 Other contributors that have submitted patches include (in alphabetical
 order):
 
-  Andy Waite                Matthew Todd              Steven Moazami
-  Anthony Panozzo           Mike Lundy                Sung Pae
-  Daniel Hahler             Nate Kane                 Thomas Pelletier
-  Felix Tjandrawibawa       Nicholas Alpi             Victor Hugo Borja
-  Gary Bernhardt            Nadav Samet               Vít Ondruch
-  Ivan Ukhov                Noon Silk                 Woody Peterson
-  Jeff Kreeftmeijer         Paul Jolly                Yan Pritzker
-  Lucas de Vries            Rainux Luo                Zak Johnson
-  Marcus Brito              Scott Bronson
-  Marian Schubert           Seth Fowler
+  Andy Waite              Matthew Todd            Steven Moazami
+  Anthony Panozzo         Mike Lundy              Sung Pae
+  Daniel Hahler           Nadav Samet             Thomas Pelletier
+  Felix Tjandrawibawa     Nate Kane               Victor Hugo Borja
+  Gary Bernhardt          Nicholas Alpi           Vít Ondruch
+  Ivan Ukhov              Noon Silk               Woody Peterson
+  Jeff Kreeftmeijer       Paul Jolly              Yan Pritzker
+  Lucas de Vries          Rainux Luo              Yiding Jia
+  Marcus Brito            Scott Bronson           Zak Johnson
+  Marian Schubert         Seth Fowler
 
 As this was the first Vim plug-in I had ever written I was heavily influenced
 by the design of the LustyExplorer plug-in by Stephen Bach, which I understand
@@ -764,7 +772,7 @@ PayPal to win@wincent.com:
 
 LICENSE                                         *command-t-license*
 
-Copyright 2010-2013 Wincent Colaiuta. All rights reserved.
+Copyright 2010-2014 Wincent Colaiuta. All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:
@@ -789,6 +797,11 @@ POSSIBILITY OF SUCH DAMAGE.
 
 HISTORY                                         *command-t-history*
 
+1.7 (unreleased)
+
+- added |g:CommandTInputDebounce|, which can be used to improve responsiveness
+  in large file hierarchies (based on patch from Yiding Jia)
+
 1.6.1 (22 December 2013)
 
 - defer processor count detection until runtime (makes it possible to sensibly

plugin/command-t.vim

@@ -1,5 +1,5 @@
 " command-t.vim
-" Copyright 2010-2013 Wincent Colaiuta. All rights reserved.
+" Copyright 2010-2014 Wincent Colaiuta. All rights reserved.
 "
 " Redistribution and use in source and binary forms, with or without
 " modification, are permitted provided that the following conditions are met:
@@ -92,6 +92,10 @@ if !has('ruby')
   finish
 endif
 
+function CommandTListMatches()
+  ruby $command_t.list_matches
+endfunction
+
 function CommandTHandleKey(arg)
   ruby $command_t.handle_key
 endfunction

ruby/command-t/controller.rb

@@ -1,4 +1,4 @@
-# Copyright 2010-2013 Wincent Colaiuta. All rights reserved.
+# Copyright 2010-2014 Wincent Colaiuta. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are met:
@@ -95,7 +95,7 @@ def quickfix
     def refresh
       return unless @active_finder && @active_finder.respond_to?(:flush)
       @active_finder.flush
-      list_matches
+      list_matches!
     end
 
     def flush
@@ -109,7 +109,7 @@ def handle_key
       key = ::VIM::evaluate('a:arg').to_i.chr
       if @focus == @prompt
         @prompt.add! key
-        list_matches
+        @needs_update = true
       else
         @match_window.find key
       end
@@ -118,14 +118,14 @@ def handle_key
     def backspace
       if @focus == @prompt
         @prompt.backspace!
-        list_matches
+        @needs_update = true
       end
     end
 
     def delete
       if @focus == @prompt
         @prompt.delete!
-        list_matches
+        @needs_update.true
       end
     end
 
@@ -155,7 +155,7 @@ def select_prev
 
     def clear
       @prompt.clear!
-      list_matches
+      list_matches!
     end
 
     def cursor_left
@@ -182,8 +182,25 @@ def unload
       @match_window.unload
     end
 
+    def list_matches(options = {})
+      return unless @needs_update || options[:force]
+
+      @matches = @active_finder.sorted_matches_for(
+        @prompt.abbrev,
+        :limit   => match_limit,
+        :threads => CommandT::Util.processor_count
+      )
+      @match_window.matches = @matches
+
+      @needs_update = false
+    end
+
   private
 
+    def list_matches!
+      list_matches(:force => true)
+    end
+
     def show
       @initial_window   = $curwin
       @initial_buffer   = $curbuf
@@ -196,6 +213,7 @@ def show
       @focus            = @prompt
       @prompt.focus
       register_for_key_presses
+      set_up_autocmds
       clear # clears prompt and lists matches
     end
 
@@ -333,6 +351,16 @@ def register_for_key_presses
       end
     end
 
+    def set_up_autocmds
+      debounce_interval = get_number('g:CommandTInputDebounce') || 50
+
+      ::VIM::command 'augroup Command-T'
+      ::VIM::command 'au!'
+      ::VIM::command 'autocmd CursorHold <buffer> :call CommandTListMatches()'
+      ::VIM::command "setlocal updatetime=#{debounce_interval}"
+      ::VIM::command 'augroup END'
+    end
+
     # Returns the desired maximum number of matches, based on available
     # vertical space and the g:CommandTMaxHeight option.
     def match_limit
@@ -342,15 +370,6 @@ def match_limit
       limit
     end
 
-    def list_matches
-      @matches = @active_finder.sorted_matches_for(
-        @prompt.abbrev,
-        :limit   => match_limit,
-        :threads => CommandT::Util.processor_count
-      )
-      @match_window.matches = @matches
-    end
-
     def buffer_finder
       @buffer_finder ||= CommandT::BufferFinder.new
     end