Refactoring code to split redis service and fetch actions inside the …

…application

Gemfile

@@ -12,6 +12,7 @@ gem "jquery-rails"
 gem "jbuilder", "~> 2.0"
 gem "redis"
 gem "friendly_id"
+gem "connection_pool", "~> 2.2.0"
 
 group :development, :test do
   gem "byebug"

Gemfile.lock

@@ -53,6 +53,7 @@ GEM
       coffee-script-source
       execjs
     coffee-script-source (1.9.1.1)
+    connection_pool (2.2.0)
     debug_inspector (0.0.2)
     dotenv (2.0.2)
     dotenv-rails (2.0.2)
@@ -159,6 +160,7 @@ DEPENDENCIES
   better_errors
   byebug
   coffee-rails (~> 4.1.0)
+  connection_pool (~> 2.2.0)
   dotenv-rails
   friendly_id
   immigrant

app/controllers/application_controller.rb

@@ -2,4 +2,10 @@ class ApplicationController < ActionController::Base
   # Prevent CSRF attacks by raising an exception.
   # For APIs, you may want to use :null_session instead.
   protect_from_forgery with: :exception
+
+  before_action :set_most_read_news
+
+  def set_most_read_news
+    @most_read_news = ::MostReadNews.new.fetch
+  end
 end

app/controllers/news_controller.rb

@@ -10,15 +10,9 @@ def index
   # GET /news/1
   # GET /news/1.json
   def show
-    begin
-      # Using the ID column as a 'member' because the slug may change
-      $redis.zincrby(:page_counter, 1, News.find(params[:id]).id)
-      # Tag script <%= javascript_tag nil, src: count_page_path(request.original_fullpath) %>
-      # To get top read: `$redis.zrangebyscore(:page_counter, :'-inf', :'+inf').reverse`
-      # optional: `withscore: true`
-      @most_read = $redis.zrangebyscore(:page_counter, :'-inf', :'+inf', withscores: true).reverse
-    rescue
-      @most_read = nil
+    RedisPool.redis.with do |conn|
+      pageview_repository = PageViewRepository.new
+      pageview_repository.increment_news(News.find(params[:id]))
     end
   end
 

app/repositories/page_view_repository.rb

@@ -0,0 +1,26 @@
+class PageViewRepository
+  def redis(options = {}, &block)
+    @redis ||= RedisPool.redis.with(options, &block)
+  end
+
+  def increment_news(news)
+    redis do |conn|
+      conn.zincrby(:news_counter, 1, news.id)
+    end
+
+  rescue => e
+    logger.tagged("PAGEVIEW") { logger.error("Error increment pageview: #{e.message} . Trace: #{e.backtrace.join(" | ")}") }
+  end
+
+  def most_read_ids
+    redis do |conn|
+      conn.zrevrangebyscore(:news_counter, "+inf", "-inf", limit: [0, 5]) || []
+    end
+  rescue => e
+    logger.tagged("PAGEVIEW") { logger.error("Error while retrieving most read news: #{e.message} . Trace: #{e.backtrace.join(" | ")}") }
+  end
+
+  def logger
+    @logger ||= ActiveSupport::TaggedLogging.new(Rails.logger)
+  end
+end

app/use_cases/most_read_news.rb

@@ -0,0 +1,11 @@
+class MostReadNews
+  def pageview_repository
+    @pageview_repository ||= PageViewRepository.new
+  end
+
+  def fetch
+    ids = PageViewRepository.new.most_read_ids
+    ids.any? ? News.where(id: ids).order("field(id, #{ids.join(",")})") : []
+  end
+end
+

app/views/news/index.html.erb

@@ -18,6 +18,16 @@
         <td><%= link_to 'Destroy', news, method: :delete, data: { confirm: 'Are you sure?' } %></td>
       </tr>
     <% end %>
+    <% if @most_read_news.any? %>
+      <tr>
+        <th>Most Read News</th>
+      </tr>
+      <% @most_read_news.each do |news| %>
+        <tr>
+          <td><%= news.name %></td>
+        </tr>
+      <% end -%>
+    <% end -%>
   </tbody>
 </table>
 

config/application.rb

@@ -20,6 +20,10 @@ class Application < Rails::Application
     # config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
     # config.i18n.default_locale = :de
 
+    # Loading lib directory
+    config.autoload_paths += %W(#{config.root}/lib)
+    config.autoload_paths += %W(#{config.root}/app/use_cases)
+
     # Do not swallow errors in after_commit/after_rollback callbacks.
     config.active_record.raise_in_transactional_callbacks = true
   end

lib/redis_pool.rb

@@ -0,0 +1,7 @@
+class RedisPool
+  def self.redis
+    @redis ||= ConnectionPool.new(size: 5, timeout: 5) do
+      Redis.new(host: ENV["REDIS_HOST"], port: ENV["REDIS_PORT"])
+    end
+  end
+end