Modifying Stream#update_last_event to consider mode.

The mtime mode is the default, and the only thing to do is the same old behavior of storing the last event time.
The cache mode involves more work, going through each path and storing a File::Stat object for each file.

lib/fsevents/stream.rb

@@ -2,7 +2,7 @@
 
 module FSEvents
   class Stream
-    attr_reader :stream, :mode, :last_event
+    attr_reader :stream, :mode, :last_event, :dirs
     attr_reader :allocator, :context, :paths, :since, :latency, :flags, :callback
 
     class StreamError < StandardError; end
@@ -18,6 +18,7 @@ def initialize(*paths, &callback)
 
       @mode = options[:mode] || :mtime
       raise ArgumentError, "Mode '#{mode}' unknown" unless MODES.include?(@mode)
+      @dirs = {}
 
       paths = Dir.pwd if paths.empty?
 
@@ -58,7 +59,17 @@ def start
     end
 
     def update_last_event
-      @last_event = Time.now
+      case mode
+      when :mtime
+        @last_event = Time.now
+      when :cache
+        paths.each do |path|
+          dirs[path] = {}
+          Dir["#{path}/*"].each do |file|
+            dirs[path][file] = File::Stat.new(file)
+          end
+        end
+      end
     end
 
     def startup

spec/stream_spec.rb

@@ -419,11 +419,79 @@
   end
 
   describe 'updating its last event' do
-    it 'should store the last event time' do
-      now = Time.now
-      Time.stubs(:now).returns(now)
-      @stream.update_last_event
-      @stream.last_event.should == now
+    describe 'when mode is mtime' do
+      before :each do
+        @stream.stubs(:mode).returns(:mtime)
+      end
+
+      it 'should store the last event time' do
+        now = Time.now
+        Time.stubs(:now).returns(now)
+        @stream.update_last_event
+        @stream.last_event.should == now
+      end
+    end
+
+    describe 'when mode is cache' do
+      before :each do
+        @stream.stubs(:mode).returns(:cache)
+        @files = Array.new(5) { |i|  stub("file #{i+1}") }
+        @stats = Array.new(5) { |i|  stub("file #{i+1} stat") }
+
+        @files.zip(@stats).each do |file, stat|
+          File::Stat.stubs(:new).with(file).returns(stat)
+        end
+
+        Dir.stubs(:[]).returns(@files)
+      end
+
+      it 'should get the contents of its path' do
+        Dir.expects(:[]).with("#{@path}/*").returns([])
+        @stream.update_last_event
+      end
+
+      it 'should get stat objects for the path contents' do
+        @files.zip(@stats).each do |file, stat|
+          File::Stat.expects(:new).with(file).returns(stat)
+        end
+        @stream.update_last_event
+      end
+
+      it 'should cache the stat objects' do
+        @stream.update_last_event
+
+        @files.zip(@stats).each do |file, stat|
+          @stream.dirs[@path][file].should == stat
+        end
+      end
+
+      it 'should update already-existent cache entries' do
+        file = @files[3]
+        val  = @stats[3]
+        @stream.dirs[@path] = { file => 'some other val' }
+
+        @stream.update_last_event
+        @stream.dirs[@path][file].should == val
+      end
+
+      it 'should remove non-needed cache entries' do
+        file = 'some other file'
+        @stream.dirs[@path] = { file => 'some val' }
+
+        @stream.update_last_event
+        @stream.dirs[@path].should_not have_key(file)
+      end
+
+      it 'should handle multiple paths' do
+        other_path = '/other/path'
+        paths = [@path, other_path]
+        @stream.stubs(:paths).returns(paths)
+
+        paths.each do |path|
+          Dir.expects(:[]).with("#{path}/*").returns([])
+        end
+        @stream.update_last_event
+      end
     end
   end