Add g:CommandTMaxCachedDirectories option

This allows the user to specify an upper limit on the number of caches
which Command-T will use when changing directories. The default of 1
preserves the existing behavior, meaning that each time you change into
a different directory, Command-T will scan it.

Set to a higher number to increase the number of cached directories, or
to 0 for no limit at all.

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

doc/command-t.txt

@@ -399,6 +399,16 @@ Following is a list of all available options:
       current directory. Any directories at levels beyond this depth will be
       skipped.
 
+                                               *g:CommandTMaxCachedDirectories*
+  |g:CommandTMaxCachedDirectories|                           number (default 1)
+
+      The maximum number of directories whose contents should be cached when
+      recursively scanning. With the default value of 1, each time you change
+      directories the cache will be emptied and Command-T will have to
+      rescan. Higher values will make Command-T hold more directories in the
+      cache, bringing performance at the cost of memory usage. If set to 0,
+      there is no limit on the number of cached directories.
+
                                                *g:CommandTMaxHeight*
   |g:CommandTMaxHeight|                          number (default: 0)
 
@@ -650,6 +660,11 @@ POSSIBILITY OF SUCH DAMAGE.
 
 HISTORY                                         *command-t-history*
 
+1.3 (not yet released)
+
+- added the option to maintain multiple caches when changing among
+  directories; see the accompanying |g:CommandTMaxCachedDirectories| setting
+
 1.2.1 (30 April 2011)
 
 - Remove duplicate copy of the documentation that was causing "Duplicate tag"

ruby/command-t/controller.rb

@@ -171,8 +171,9 @@ def set_up_max_height
 
     def set_up_file_finder
       @file_finder = CommandT::FileFinder.new nil,
-        :max_files              => get_number('g:CommandTMaxFiles'),
         :max_depth              => get_number('g:CommandTMaxDepth'),
+        :max_files              => get_number('g:CommandTMaxFiles'),
+        :max_caches             => get_number('g:CommandTMaxCachedDirectories'),
         :always_show_dot_files  => get_bool('g:CommandTAlwaysShowDotFiles'),
         :never_show_dot_files   => get_bool('g:CommandTNeverShowDotFiles'),
         :scan_dot_directories   => get_bool('g:CommandTScanDotDirectories')

ruby/command-t/scanner/file_scanner.rb

@@ -32,15 +32,18 @@ class FileLimitExceeded < ::RuntimeError; end
 
     def initialize path = Dir.pwd, options = {}
       @paths                = {}
+      @paths_keys           = []
       @path                 = path
       @max_depth            = options[:max_depth] || 15
       @max_files            = options[:max_files] || 10_000
+      @max_caches           = options[:max_caches] || 1
       @scan_dot_directories = options[:scan_dot_directories] || false
     end
 
     def paths
       return @paths[@path] if @paths.has_key?(@path)
       begin
+        ensure_cache_under_limit
         @paths[@path] = []
         @depth        = 0
         @files        = 0
@@ -57,6 +60,15 @@ def flush
 
   private
 
+    def ensure_cache_under_limit
+      # Ruby 1.8 doesn't have an ordered hash, so use a separate stack to
+      # track and expire the oldest entry in the cache
+      if @max_caches > 0 && @paths_keys.length >= @max_caches
+        @paths.delete @paths_keys.shift
+      end
+      @paths_keys << @path
+    end
+
     def path_excluded? path
       # first strip common prefix (@path) from path to match VIM's behavior
       path = path[(@prefix_len + 1)..-1]