Issue #175, setting the mtime of each asset package to the mtime of the most recently modified file.

Author: jashkenas

lib/jammit/packager.rb

@@ -44,7 +44,7 @@ def precache_all(output_dir=nil, base_url=nil)
         if Jammit.embed_assets
           cache(p, 'css', pack_stylesheets(p, :datauri), output_dir, :datauri)
           if Jammit.mhtml_enabled && base_url
-            mtime = Time.now
+            mtime = latest_mtime package_for(p, :css)[:paths]
             asset_url = "#{base_url}#{Jammit.asset_url(p, :css, :mhtml, mtime)}"
             cache(p, 'css', pack_stylesheets(p, :mhtml, asset_url), output_dir, :mhtml, mtime)
           end
@@ -55,9 +55,10 @@ def precache_all(output_dir=nil, base_url=nil)
     # Caches a single prebuilt asset package and gzips it at the highest
     # compression level. Ensures that the modification time of both both
     # variants is identical, for web server caching modules, as well as MHTML.
-    def cache(package, extension, contents, output_dir, suffix=nil, mtime=Time.now)
+    def cache(package, extension, contents, output_dir, suffix=nil, mtime=nil)
       FileUtils.mkdir_p(output_dir) unless File.exists?(output_dir)
       raise OutputNotWritable, "Jammit doesn't have permission to write to \"#{output_dir}\"" unless File.writable?(output_dir)
+      mtime ||= latest_mtime package_for(package, extension.to_sym)[:paths]
       files = []
       files << file_name = File.join(output_dir, Jammit.filename(package, extension, suffix))
       File.open(file_name, 'wb+') {|f| f.write(contents) }
@@ -105,6 +106,12 @@ def glob_files(glob)
       Jammit.warn("No assets match '#{glob}'") if paths.empty?
       paths
     end
+    
+    # Get the latest mtime of a list of files (plus the config path).
+    def latest_mtime(paths)
+      paths += [Jammit.config_path]
+      paths.map {|p| File.mtime(p) }.max || Time.now
+    end
 
     # Return a list of all of the packages that should be cached. If "force" is
     # true, this is all of them -- otherwise only the packages that are missing