(#12126) Implement reloading changed files

This adds a reload_changed method to the autoloader. It checks all loaded
files for changes (based on the mtime of the files) and reload any paths that
have changed. Deleted files are still listed as loaded since there is no way
to actually unload code in Ruby.

lib/puppet/util/autoload.rb

@@ -13,12 +13,13 @@ class Puppet::Util::Autoload
   @loaded = {}
 
   class << self
-    attr_reader :autoloaders, :loaded
+    attr_reader :autoloaders
+    attr_accessor :loaded
     private :autoloaders, :loaded
 
     # List all loaded files.
     def list_loaded
-      @loaded.keys.sort { |a,b| a[0] <=> b[0] }.collect do |path, hash|
+      loaded.keys.sort { |a,b| a[0] <=> b[0] }.collect do |path, hash|
         "#{path}: #{hash[:file]}"
       end
     end
@@ -30,15 +31,25 @@ def list_loaded
     # reloaded.
     def loaded?(path)
       path = path.to_s.sub(/\.rb$/, '')
-      @loaded.include?(path)
+      loaded.include?(path)
     end
 
     # Save the fact that a given path has been loaded.  This is so
     # we can load downloaded plugins if they've already been loaded
     # into memory.
     def mark_loaded(name, file)
       $" << name + ".rb" unless $".include?(name)
-      @loaded[name] = [file, File.mtime(file)]
+      loaded[name] = [file, File.mtime(file)]
+    end
+
+    def changed?(name)
+      return true unless loaded.include?(name)
+      file, old_mtime = loaded[name]
+      begin
+        old_mtime != File.mtime(file)
+      rescue Errno::ENOENT
+        true
+      end
     end
 
     # Load a single plugin by name.  We use 'load' here so we can reload a
@@ -73,6 +84,10 @@ def loadall(path)
       end
     end
 
+    def reload_changed
+      loaded.keys.each { |file| load_file(file) if changed?(file) }
+    end
+
     def files_to_load(path)
       search_directories.map {|dir| files_in_dir(dir, path) }.flatten.uniq
     end

spec/unit/util/autoload_spec.rb

@@ -151,4 +151,58 @@
       @autoload.loadall
     end
   end
+
+  describe "when reloading files" do
+    before :each do
+      @file_a = "/a/file.rb"
+      @file_b = "/b/file.rb"
+      @first_time = Time.utc(2010, 'jan', 1, 6, 30)
+      @second_time = @first_time + 60
+    end
+
+    after :each do
+      $LOADED_FEATURES.delete("a/file.rb")
+      $LOADED_FEATURES.delete("b/file.rb")
+    end
+
+    describe "in one directory" do
+      before :each do
+        @autoload.class.stubs(:searchpath).returns %w{/a}
+        File.expects(:mtime).with(@file_a).returns(@first_time)
+        @autoload.class.mark_loaded("file", @file_a)
+      end
+
+      it "should reload if mtime changes" do
+        File.stubs(:mtime).with(@file_a).returns(@first_time + 60)
+        File.stubs(:exist?).with(@file_a).returns true
+        Kernel.expects(:load).with(@file_a, optionally(anything))
+        @autoload.class.reload_changed
+      end
+
+      it "should do nothing if the file is deleted" do
+        File.expects(:mtime).with(@file_a).raises(Errno::ENOENT)
+        File.stubs(:exist?).with(@file_a).returns false
+        Kernel.expects(:load).never
+        @autoload.class.reload_changed
+      end
+    end
+
+    describe "in two directories" do
+      before :each do
+        @autoload.class.stubs(:searchpath).returns %w{/a /b}
+        File.expects(:mtime).with(@file_a).returns(@first_time)
+        @autoload.class.mark_loaded("file", @file_a)
+      end
+
+      it "should load b/file when a/file is deleted" do
+        File.stubs(:mtime).with(@file_a).raises(Errno::ENOENT)
+        File.stubs(:exist?).with(@file_a).returns false
+        File.stubs(:exist?).with(@file_b).returns true
+        File.stubs(:mtime).with(@file_b).returns @first_time
+        Kernel.expects(:load).with(@file_b, optionally(anything))
+        @autoload.class.reload_changed
+        @autoload.class.send(:loaded)["file"].should == [@file_b, @first_time]
+      end
+    end
+  end
 end