Works well enough for now

Rakefile

@@ -46,3 +46,7 @@ Rake::RDocTask.new do |rdoc|
   rdoc.rdoc_files.include('lib/**/*.rb')
 end
 
+desc "Start redis server"
+task :redis do
+  exec "redis-server /etc/conf.d/redis.conf"
+end

lib/resourceful-redis-cache-manager.rb

@@ -0,0 +1,80 @@
+
+require 'resourceful'
+require 'redis'
+require 'json'
+require 'digest/md5'
+require 'hitimes'
+
+module Resourceful
+  class RedisCacheManager
+
+    attr_reader :db
+
+    def initialize(options)
+      @logger = options[:logger]
+      @db = Redis.new(options)
+    end
+
+    def lookup(request)
+      response = nil
+      total_timer = Hitimes::TimedMetric.now("Total cache lookup")
+      fetch_timer = Hitimes::TimedMetric.new("Fetching from redis")
+
+      if metadata = fetch_timer.measure { db.list_range(request.uri.to_s, 0, -1) }
+        metadata.detect { |meta|
+          json = Marshal.load(meta)
+          if valid_for?(request, json[:vary_header_values])
+            key = json[:key]
+            text = fetch_timer.measure { db.get(key) }
+            response = Marshal.load(text)
+            total_timer.stop
+            @logger.debug("    [Redis] cache read: %0.4fs (%0.1f%%) fetching, %0.4f total" %
+                          [fetch_timer.sum, fetch_timer.sum / total_timer.sum * 100, total_timer.sum ])
+            true
+          else
+            @logger.debug("[Redis] cache miss")
+          end
+
+        }
+      end
+
+
+      response
+    end
+
+    def store(request, response)
+      @logger.info("Storing in cache")
+      key = Digest::MD5.hexdigest(request.uri.to_s)
+
+      response.header['Cache-Control'].match(/max-age=(\d+)/) if response.header['Cache-Control']
+      expires = $1
+      db.set(key, Marshal.dump(response), expires)
+
+      values = vary_header_values(request, response)
+      values = {:vary_header_values => values, :key => key}
+      text = Marshal.dump(values)
+      db.push_tail(request.uri.to_s, text)
+    end
+
+    def invalidate(url)
+      db.delete(url)
+    end
+
+    protected
+
+    def vary_header_values(request, response)
+      values = {}
+      response.header['Vary'].each do |name|
+        values[name] = request.header[name]
+      end if response.header['Vary']
+      values
+    end
+
+    def valid_for?(request, vary_header_values)
+      vary_header_values.all? do |name, value|
+        request.header[name] == value
+      end
+    end
+
+  end
+end