fix story pagination and caching for logged-out users

use a file store so each unicorn process can share the same set of
files (using redis would probably be cleaner)

put page number into how hash when creating the cache key

app/controllers/home_controller.rb

@@ -122,9 +122,9 @@ class HomeController < ApplicationController
 
 private
   def find_stories(how = {})
-    @page = 1
+    @page = how[:page] = 1
     if params[:page].to_i > 0
-      @page = params[:page].to_i
+      @page = how[:page] = params[:page].to_i
     end
 
     # guest views have caching, but don't bother for logged-in users or dev or
@@ -193,7 +193,7 @@ private
       )
     end
 
-    if how[:recent] && @page == 1
+    if how[:recent] && how[:page] == 1
       # try to help recently-submitted stories that didn't gain traction
 
       story_ids = []
@@ -228,7 +228,7 @@ private
     ).limit(
       STORIES_PER_PAGE + 1
     ).offset(
-      (@page - 1) * STORIES_PER_PAGE
+      (how[:page] - 1) * STORIES_PER_PAGE
     ).order(
       (how[:newest] || how[:recent]) ? "stories.created_at DESC" : "hotness"
     ).to_a

config/application.rb

@@ -30,7 +30,7 @@ module Lobsters
     # Raise an exception when using mass assignment with unpermitted attributes
     config.action_controller.action_on_unpermitted_parameters = :raise
 
-    config.cache_store = :memory_store
+    config.cache_store = :file_store, "#{config.root}/tmp/cache/"
   end
 end