stories: show archive link to archive.is

app/views/stories/_listdetail.html.erb

@@ -163,6 +163,11 @@ class="story <%= story.vote && story.vote[:vote] == 1 ? "upvoted" : "" %>
             (hidden by <%= pluralize(story.hider_count, "user") %>)
           <% end %>
         <% end %>
+        <% if story.url.present? %>
+          |
+          <a href="https://archive.is/<%= story.url %>" rel="nofollow"
+            target="_new">cached</a>
+        <% end %>
         <% if !story.is_gone? %>
           <span class="comments_label">
             |

extras/story_cacher.rb

@@ -41,6 +41,14 @@ class StoryCacher
       Rails.logger.error "error fetching #{db_url}: #{e.message}"
     end
 
+    begin
+      s = Sponge.new
+      s.timeout = 45
+      s.fetch("https://archive.is/#{db_url}")
+    rescue => e
+      Rails.logger.error "error caching #{db_url}: #{e.message}"
+    end
+
     nil
   end
 end