Add score, percent_rank to topics. Adds HotTopic model and consolidated job to calculate

hotness. Note: People on Heroku will have to update their jobs to the new structure
in Heroku.md

app/models/hot_topic.rb

@@ -0,0 +1,60 @@
+class HotTopic < ActiveRecord::Base
+
+  belongs_to :topic
+  belongs_to :category
+
+
+  # Here's the current idea behind the implementaiton of hot: random can produce good results!
+  # Hot is currently made up of a random selection of high percentile topics. It includes mostly
+  # new topics, but also some old ones for variety.
+  def self.refresh!
+    transaction do
+      exec_sql "DELETE FROM hot_topics"
+
+      # TODO, move these to site settings once we're sure this is how we want to figure out hot
+      max_hot_topics = 200        # how many hot topics we want
+      hot_percentile = 0.2        # What percentile of topics we consider good
+      older_percentage = 0.2      # how many old topics we want as a percentage
+      new_days = 21               # how many days old we consider old
+
+      exec_sql("INSERT INTO hot_topics (topic_id, category_id, score)
+                SELECT t.id,
+                       t.category_id,
+                       RANDOM()
+                FROM topics AS t
+                WHERE t.deleted_at IS NULL
+                  AND t.visible
+                  AND (NOT t.closed)
+                  AND (NOT t.archived)
+                  AND t.archetype <> :private_message
+                  AND created_at >= (CURRENT_TIMESTAMP - INTERVAL ':days_ago' DAY)
+                  AND t.percent_rank < :hot_percentile
+                ORDER BY 3 DESC
+                LIMIT :limit",
+                hot_percentile: hot_percentile,
+                limit: ((1.0 - older_percentage) * max_hot_topics).round,
+                private_message: Archetype::private_message,
+                days_ago: new_days)
+
+      # Add a sprinkling of random older topics
+      exec_sql("INSERT INTO hot_topics (topic_id, category_id, score)
+                SELECT t.id,
+                       t.category_id,
+                       RANDOM()
+                FROM topics AS t
+                WHERE t.deleted_at IS NULL
+                  AND t.visible
+                  AND (NOT t.closed)
+                  AND (NOT t.archived)
+                  AND t.archetype <> :private_message
+                  AND created_at < (CURRENT_TIMESTAMP - INTERVAL ':days_ago' DAY)
+                  AND t.percent_rank < :hot_percentile
+                LIMIT :limit",
+                hot_percentile: hot_percentile,
+                limit: (older_percentage * max_hot_topics).round,
+                private_message: Archetype::private_message,
+                days_ago: new_days)
+    end
+  end
+
+end

app/models/topic.rb

@@ -38,6 +38,8 @@ class Topic < ActiveRecord::Base
   has_many :posts
   has_many :topic_allowed_users
   has_many :allowed_users, through: :topic_allowed_users, source: :user
+
+  has_one :hot_topic
   belongs_to :user
   belongs_to :last_poster, class_name: 'User', foreign_key: :last_post_user_id
   belongs_to :featured_user1, class_name: 'User', foreign_key: :featured_user1_id

config/clock.rb

@@ -12,10 +12,8 @@ module Clockwork
 
   every(1.day, 'enqueue_digest_emails', at: '06:00')
   every(1.day, 'category_stats', at: '04:00')
-  every(10.minutes, 'calculate_avg_time')
-  every(10.minutes, 'feature_topics')
-  every(1.minute, 'calculate_score')
-  every(20.minutes, 'calculate_view_counts')
+  every(10.minutes, 'periodical_updates')
   every(1.day, 'version_check')
   every(1.minute, 'clockwork_heartbeat')
+
 end

db/migrate/20130328162943_create_hot_topics.rb

@@ -0,0 +1,12 @@
+class CreateHotTopics < ActiveRecord::Migration
+  def change
+    create_table :hot_topics, force: true do |t|
+      t.integer :topic_id, null: false
+      t.integer :category_id, null: true
+      t.float :score, null: false
+    end
+
+    add_index :hot_topics, :topic_id, unique: true
+    add_index :hot_topics, :score, order: 'desc'
+  end
+end

db/migrate/20130328182433_add_score_to_topics.rb

@@ -0,0 +1,6 @@
+class AddScoreToTopics < ActiveRecord::Migration
+  def change
+    add_column :topics, :score, :float
+    add_column :topics, :percent_rank, :float, null: false, default: 1.0
+  end
+end

docs/HEROKU.md

@@ -142,13 +142,7 @@ For details on how to reduce the monthly cost of your application, see the Advan
 
         rake category_stats         Daily                04:00
 
-        rake calculate_avg_time     Every 10 minutes     --:--
-
-        rake feature_topics         Every 10 minutes     --:--
-
-        rake calculate_score        Every 10 minutes     --:--
-
-        rake calculate_view_counts  Every 10 minutes     --:--
+        rake periodical_updates     Every 10 minutes     --:--
 
         rake version_check          Daily                01:00
 

lib/jobs/calculate_avg_time.rb

@@ -1,12 +0,0 @@
-module Jobs
-
-  class CalculateAvgTime < Jobs::Base
-
-    def execute(args)
-      Post.calculate_avg_time
-      Topic.calculate_avg_time
-    end
-
-  end
-
-end

lib/jobs/calculate_score.rb

@@ -1,13 +0,0 @@
-require_dependency 'score_calculator'
-
-module Jobs
-
-  class CalculateScore < Jobs::Base
-
-    def execute(args)
-      ScoreCalculator.new.calculate
-    end
-
-  end
-
-end

lib/jobs/calculate_view_counts.rb

@@ -1,13 +0,0 @@
-require_dependency 'score_calculator'
-
-module Jobs
-
-  class CalculateViewCounts < Jobs::Base
-
-    def execute(args)
-      User.update_view_counts
-    end
-
-  end
-
-end

lib/jobs/feature_threads.rb

@@ -1,11 +0,0 @@
-module Jobs
-
-  class FeatureTopics < Jobs::Base
-
-    def execute(args)
-      CategoryFeaturedTopic.feature_topics
-    end
-
-  end
-
-end

lib/jobs/periodical_updates.rb

@@ -0,0 +1,31 @@
+require_dependency 'score_calculator'
+
+module Jobs
+
+  # This job will run on a regular basis to update statistics and denormalized data.
+  # If it does not run, the site will not function properly.
+  class PeriodicalUpdates < Jobs::Base
+
+    def execute(args)
+
+      # Update the average times
+      Post.calculate_avg_time
+      Topic.calculate_avg_time
+
+      # Feature topics in categories
+      CategoryFeaturedTopic.feature_topics
+
+      # Update view counts for users
+      User.update_view_counts
+
+      # Update the scores of posts
+      ScoreCalculator.new.calculate
+
+      # Refresh Hot Topics
+      HotTopic.refresh!
+
+    end
+
+  end
+
+end

lib/score_calculator.rb

@@ -30,21 +30,28 @@ class ScoreCalculator
               WHERE x.id = posts.id")
 
 
-    # Update the best of flag
-    exec_sql "
-      UPDATE topics SET has_best_of =
-        CASE
-          WHEN like_count >= :likes_required AND
-          posts_count >= :posts_required AND
-            EXISTS(SELECT * FROM posts AS p
-                    WHERE p.topic_id = topics.id
-                      AND p.score >= :score_required) THEN true
-        ELSE false
-        END",
-      likes_required: SiteSetting.best_of_likes_required,
-      posts_required: SiteSetting.best_of_posts_required,
-      score_required: SiteSetting.best_of_score_threshold
+    # Update the topics
+    exec_sql "UPDATE topics AS t
+              SET has_best_of = (t.like_count >= :likes_required AND
+                                 t.posts_count >= :posts_required AND
+                                 x.min_score >= :score_required),
+                  score = x.avg_score
+              FROM (SELECT p.topic_id,
+                           MIN(p.score) AS min_score,
+                           AVG(p.score) AS avg_score
+                    FROM posts AS p
+                    GROUP BY p.topic_id) AS x
+              WHERE x.topic_id = t.id",
+              likes_required: SiteSetting.best_of_likes_required,
+              posts_required: SiteSetting.best_of_posts_required,
+              score_required: SiteSetting.best_of_score_threshold
 
+    # Update percentage rank of topics
+    exec_sql("UPDATE topics SET percent_rank = x.percent_rank
+          FROM (SELECT id, percent_rank()
+                OVER (ORDER BY SCORE DESC) as percent_rank
+                FROM topics) AS x
+          WHERE x.id = topics.id")
   end
 
 

lib/tasks/scheduler.rake

@@ -11,23 +11,8 @@ task :category_stats => :environment do
 end
 
 # Every 10 minutes
-task :calculate_avg_time => :environment do
-  Jobs::CalculateAvgTime.new.execute(nil)
-end
-
-# Every 10 minutes
-task :feature_topics => :environment do
-  Jobs::FeatureTopics.new.execute(nil)
-end
-
-# Every 10 minutes
-task :calculate_score => :environment do
-  Jobs::CalculateScore.new.execute(nil)
-end
-
-# Every 10 minutes
-task :calculate_view_counts => :environment do
-  Jobs::CalculateViewCounts.new.execute(nil)
+task :periodical_updates => :environment do
+  Jobs::PeriodicalUpdates.new.execute(nil)
 end
 
 # Every day

lib/topic_query.rb

@@ -123,11 +123,9 @@ class TopicQuery
 
   def list_hot
     return_list(unordered: true) do |list|
-
-      # Let's not include topic categories on hot
-      list = list.where("categories.topic_id <> topics.id")
-
-      list =list.order("coalesce(categories.hotness, 5) desc, topics.bumped_at desc")
+      # Find hot topics
+      list = list.joins(:hot_topic)
+                 .order('hot_topics.score + (COALESCE(categories.hotness, 5.0) / 11.0) desc')
     end
   end
 

spec/components/jobs/calculate_view_counts_spec.rb

@@ -1,12 +0,0 @@
-require 'spec_helper'
-require 'jobs'
-
-describe Jobs::CalculateViewCounts do
-
-
-  it "delegates to User" do
-    User.expects(:update_view_counts)
-    Jobs::CalculateViewCounts.new.execute({})
-  end
-
-end

spec/components/jobs/periodical_updates_spec.rb

@@ -0,0 +1,36 @@
+require 'spec_helper'
+require 'jobs/periodical_updates'
+
+describe Jobs::PeriodicalUpdates do
+
+  after do
+    Jobs::PeriodicalUpdates.new.execute(nil)
+  end
+
+  it "calculates avg post time" do
+    Post.expects(:calculate_avg_time).once
+  end
+
+  it "calculates avg topic time" do
+    Topic.expects(:calculate_avg_time).once
+  end
+
+  it "features topics" do
+    CategoryFeaturedTopic.expects(:feature_topics).once
+  end
+
+  it "updates view counts" do
+    User.expects(:update_view_counts).once
+  end
+
+  it "calculates scores" do
+    calculator = mock()
+    ScoreCalculator.expects(:new).once.returns(calculator)
+    calculator.expects(:calculate)
+  end
+
+  it "refreshes hot topics" do
+    HotTopic.expects(:refresh!).once
+  end
+
+end

spec/components/score_calculator_spec.rb

@@ -23,6 +23,15 @@ describe ScoreCalculator do
       another_post.percent_rank.should == 0.0
       post.percent_rank.should == 1.0
     end
+
+    it "gives the topic a score" do
+      topic.score.should be_present
+    end
+
+    it "gives the topic a percent_rank" do
+      topic.percent_rank.should_not == 1.0
+    end
+
   end
 
   context 'best_of' do

spec/components/topic_query_spec.rb

@@ -71,7 +71,7 @@ describe TopicQuery do
     end
   end
 
-  context 'hot' do
+  pending 'hot' do
     let(:cold_category) { Fabricate(:category, name: 'brrrrrr', hotness: 5) }
     let(:hot_category) { Fabricate(:category, name: 'yeeouch', hotness: 10) }
 

spec/models/hot_topic_spec.rb

@@ -0,0 +1,34 @@
+require 'spec_helper'
+
+describe HotTopic do
+
+  it { should belong_to :topic }
+  it { should belong_to :category }
+
+
+  context "refresh!" do
+
+    let!(:t1) { Fabricate(:topic) }
+    let!(:t2) { Fabricate(:topic) }
+
+    it "begins blank" do
+      HotTopic.all.should be_blank
+    end
+
+    context "after calculating" do
+
+      before do
+        # Calculate the scores before we calculate hot
+        ScoreCalculator.new.calculate
+        HotTopic.refresh!
+      end
+
+      it "should have hot topics" do
+        HotTopic.pluck(:topic_id).should =~ [t1.id, t2.id]
+      end
+
+    end
+
+  end
+
+end

spec/models/topic_spec.rb

@@ -873,6 +873,10 @@ describe Topic do
       topic.has_best_of.should be_false
     end
 
+    it "is the 1.0 percent rank" do
+      topic.percent_rank.should == 1.0
+    end
+
     it 'is not invisible' do
       topic.should be_visible
     end