avatar caching

app/controllers/avatars_controller.rb

@@ -0,0 +1,38 @@
+class AvatarsController < ApplicationController
+  ALLOWED_SIZES = [ 16, 32, 100, 200 ]
+
+  CACHE_DIR = "#{Rails.root}/public/avatars/"
+
+  def show
+    username, size = params[:username_size].to_s.scan(/\A(.+)-(\d+)\z/).first
+    size = size.to_i
+
+    if !ALLOWED_SIZES.include?(size)
+      raise ActionController::RoutingError.new("invalid size")
+    end
+
+    if !username.match(User::VALID_USERNAME)
+      raise ActionController::RoutingError.new("invalid user name")
+    end
+
+    u = User.where(:username => username).first!
+
+    if !(av = u.fetched_avatar(size))
+      raise ActionController::RoutingError.new("failed fetching avatar")
+    end
+
+    if !Dir.exists?(CACHE_DIR)
+      Dir.mkdir(CACHE_DIR)
+    end
+
+    File.open("#{CACHE_DIR}/.#{u.username}-#{size}.png", "wb+") do |f|
+      f.write av
+    end
+
+    File.rename("#{CACHE_DIR}/.#{u.username}-#{size}.png",
+      "#{CACHE_DIR}/#{u.username}-#{size}.png")
+
+    response.headers["Expires"] = 1.hour.from_now.httpdate
+    send_data av, :type => "image/png", :disposition => "inline"
+  end
+end

app/models/user.rb

@@ -142,9 +142,7 @@ class User < ActiveRecord::Base
   end
 
   def avatar_url(size = 100)
-    "https://www.gravatar.com/avatar/" +
-      Digest::MD5.hexdigest(self.email.strip.downcase) +
-      "?r=pg&d=identicon&s=#{size}"
+    Rails.application.root_url + "avatars/#{self.username}-#{size}.png"
   end
 
   def average_karma
@@ -266,6 +264,25 @@ class User < ActiveRecord::Base
     Keystore.value_for("user:#{self.id}:comments_posted").to_i
   end
 
+  def fetched_avatar(size = 100)
+    gravatar_url = "https://www.gravatar.com/avatar/" <<
+      Digest::MD5.hexdigest(self.email.strip.downcase) <<
+      "?r=pg&d=identicon&s=#{size}"
+
+    begin
+      s = Sponge.new
+      s.timeout = 3
+      res = s.fetch(gravatar_url)
+      if res.present?
+        return res
+      end
+    rescue => e
+      Rails.logger.error "error fetching #{gravatar_url}: #{e.message}"
+    end
+
+    nil
+  end
+
   def update_comments_posted_count!
     Keystore.put("user:#{self.id}:comments_posted", self.comments.active.count)
   end

config/routes.rb

@@ -106,6 +106,8 @@ Lobsters::Application.routes.draw do
     get "/u" => "users#tree"
     get "/u/:username" => "users#show", :as => "user", :format => /html|json/
 
+    get "/avatars/:username_size.png" => "avatars#show"
+
     post "/users/:username/ban" => "users#ban", :as => "user_ban"
     post "/users/:username/unban" => "users#unban", :as => "user_unban"
     post "/users/:username/disable_invitation" => "users#disable_invitation", :as => "user_disable_invite"