Refactor PathScanner to avoid Dir.glob

lib/bootsnap/load_path_cache/path_scanner.rb

@@ -5,7 +5,6 @@
 module Bootsnap
   module LoadPathCache
     module PathScanner
-      ALL_FILES = "/{,**/*/**/}*"
       REQUIRABLE_EXTENSIONS = [DOT_RB] + DL_EXTENSIONS
       NORMALIZE_NATIVE_EXTENSIONS = !DL_EXTENSIONS.include?(LoadPathCache::DOT_SO)
       ALTERNATIVE_NATIVE_EXTENSIONS_PATTERN = /\.(o|bundle|dylib)\z/
@@ -16,34 +15,47 @@ module PathScanner
         ''
       end
 
-      def self.call(path)
-        path = path.to_s
-
-        relative_slice = (path.size + 1)..-1
-        # If the bundle path is a descendent of this path, we do additional
-        # checks to prevent recursing into the bundle path as we recurse
-        # through this path. We don't want to scan the bundle path because
-        # anything useful in it will be present on other load path items.
-        #
-        # This can happen if, for example, the user adds '.' to the load path,
-        # and the bundle path is '.bundle'.
-        contains_bundle_path = BUNDLE_PATH.start_with?(path)
-
-        dirs = []
-        requirables = []
-
-        Dir.glob(path + ALL_FILES).each do |absolute_path|
-          next if contains_bundle_path && absolute_path.start_with?(BUNDLE_PATH)
-          relative_path = absolute_path.slice(relative_slice)
-
-          if File.directory?(absolute_path)
-            dirs << relative_path
-          elsif REQUIRABLE_EXTENSIONS.include?(File.extname(relative_path))
-            requirables << relative_path
+      class << self
+        def call(path)
+          path = File.expand_path(path.to_s).freeze
+
+          # If the bundle path is a descendent of this path, we do additional
+          # checks to prevent recursing into the bundle path as we recurse
+          # through this path. We don't want to scan the bundle path because
+          # anything useful in it will be present on other load path items.
+          #
+          # This can happen if, for example, the user adds '.' to the load path,
+          # and the bundle path is '.bundle'.
+          contains_bundle_path = BUNDLE_PATH.start_with?(path)
+
+          dirs = []
+          requirables = []
+          walk(path, nil) do |relative_path, absolute_path, is_directory|
+            if is_directory
+              dirs << relative_path
+              !contains_bundle_path || !absolute_path.start_with?(BUNDLE_PATH)
+            elsif relative_path.end_with?(*REQUIRABLE_EXTENSIONS)
+              requirables << relative_path
+            end
           end
+          [requirables, dirs]
         end
 
-        [requirables, dirs]
+        def walk(absolute_dir_path, relative_dir_path, &block)
+          Dir.foreach(absolute_dir_path) do |name|
+            next if name.start_with?('.')
+            relative_path = relative_dir_path ? "#{relative_dir_path}/#{name}" : name.freeze
+
+            absolute_path = "#{absolute_dir_path}/#{name}"
+            if File.directory?(absolute_path)
+              if yield relative_path, absolute_path, true
+                walk(absolute_path, relative_path, &block)
+              end
+            else
+              yield relative_path, absolute_path, false
+            end
+          end
+        end
       end
     end
   end