User counters using PostgreSQL JSON (#5373) [deploy]

Co-authored-by: Ben Halpern <bendhalpern@gmail.com>

app/models/user.rb

@@ -55,6 +55,7 @@ class User < ApplicationRecord
   has_many :blocker_blocks, class_name: "UserBlock", foreign_key: :blocker_id, inverse_of: :blocker, dependent: :delete_all
   has_many :blocked_blocks, class_name: "UserBlock", foreign_key: :blocked_id, inverse_of: :blocked, dependent: :delete_all
   has_one :pro_membership, dependent: :destroy
+  has_one :counters, class_name: "UserCounter", dependent: :destroy
   has_many :created_podcasts, class_name: "Podcast", foreign_key: :creator_id, inverse_of: :creator, dependent: :nullify
 
   mount_uploader :profile_image, ProfileImageUploader
@@ -155,6 +156,16 @@ class User < ApplicationRecord
 
   scope :dev_account, -> { find_by(id: SiteConfig.staff_user_id) }
 
+  scope :with_this_week_comments, lambda { |number|
+    includes(:counters).joins(:counters).where("(user_counters.data -> 'comments_these_7_days')::int >= ?", number)
+  }
+  scope :with_previous_week_comments, lambda { |number|
+    includes(:counters).joins(:counters).where("(user_counters.data -> 'comments_prior_7_days')::int >= ?", number)
+  }
+  scope :top_commenters, lambda { |number = 10|
+    includes(:counters).order(Arel.sql("user_counters.data -> 'comments_these_7_days' DESC")).limit(number)
+  }
+
   after_create_commit :send_welcome_notification
   after_save  :bust_cache
   after_save  :subscribe_to_mailchimp_newsletter

app/models/user_counter.rb

@@ -0,0 +1,11 @@
+class UserCounter < ApplicationRecord
+  belongs_to :user
+
+  serialize :data, HashSerializer
+  store_accessor :data, :comments_these_7_days, :comments_prior_7_days
+
+  validates :user, presence: true, uniqueness: true
+
+  validates :comments_these_7_days, numericality: { only_integer: true }
+  validates :comments_prior_7_days, numericality: { only_integer: true }
+end

app/serializers/hash_serializer.rb

@@ -0,0 +1,9 @@
+class HashSerializer
+  def self.dump(hash)
+    hash
+  end
+
+  def self.load(hash)
+    (hash || {}).with_indifferent_access
+  end
+end

db/migrate/20200106074859_create_user_counters.rb

@@ -0,0 +1,14 @@
+class CreateUserCounters < ActiveRecord::Migration[5.2]
+  def change
+    create_table :user_counters do |t|
+      t.references :user, index: { unique: true }
+      t.jsonb :data, null: false, default: {}
+
+      t.timestamps null: false
+    end
+
+    add_foreign_key :user_counters, :users, on_delete: :cascade
+
+    add_index :user_counters, :data, using: :gin
+  end
+end

db/schema.rb

@@ -11,7 +11,6 @@
 # It's strongly recommended that you check this file into your version control system.
 
 ActiveRecord::Schema.define(version: 2020_01_20_053525) do
-
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
@@ -1018,6 +1017,15 @@ ActiveRecord::Schema.define(version: 2020_01_20_053525) do
     t.index ["blocked_id", "blocker_id"], name: "index_user_blocks_on_blocked_id_and_blocker_id", unique: true
   end
 
+  create_table "user_counters", force: :cascade do |t|
+    t.datetime "created_at", null: false
+    t.jsonb "data", default: {}, null: false
+    t.datetime "updated_at", null: false
+    t.bigint "user_id"
+    t.index ["data"], name: "index_user_counters_on_data", using: :gin
+    t.index ["user_id"], name: "index_user_counters_on_user_id", unique: true
+  end
+
   create_table "users", id: :serial, force: :cascade do |t|
     t.integer "articles_count", default: 0, null: false
     t.string "available_for"
@@ -1224,6 +1232,7 @@ ActiveRecord::Schema.define(version: 2020_01_20_053525) do
   add_foreign_key "tag_adjustments", "users", on_delete: :cascade
   add_foreign_key "user_blocks", "users", column: "blocked_id"
   add_foreign_key "user_blocks", "users", column: "blocker_id"
+  add_foreign_key "user_counters", "users", on_delete: :cascade
   add_foreign_key "users_roles", "users", on_delete: :cascade
   add_foreign_key "webhook_endpoints", "oauth_applications"
   add_foreign_key "webhook_endpoints", "users"

lib/tasks/counters.rake

@@ -0,0 +1,19 @@
+namespace :counters do
+  task update_users: :environment do
+    ActiveRecord::Base.transaction do
+      # NOTE: we could bypass Rails by using SQL directly to compute the counts and update these columns
+      User.includes(:counters).find_each do |user|
+        user.build_counters unless user.counters
+
+        relation = user.comments
+
+        user.counters.comments_these_7_days = relation.where("created_at > ?", 7.days.ago).size
+        user.counters.comments_prior_7_days = relation.
+          where("created_at > ? AND created_at < ?", 14.days.ago, 7.days.ago).
+          size
+
+        user.counters.save!
+      end
+    end
+  end
+end

spec/factories/user_counters.rb

@@ -0,0 +1,6 @@
+FactoryBot.define do
+  factory :user_counter do
+    user
+    data { { comments_these_7_days: 0, comments_prior_7_days: 0 } }
+  end
+end

spec/models/user_counter_spec.rb

@@ -0,0 +1,39 @@
+require "rails_helper"
+
+RSpec.describe UserCounter, type: :model do
+  let(:counters) { build(:user_counter) }
+
+  describe "validations" do
+    describe "builtin validations" do
+      subject { build(:user_counter, user: create(:user)) }
+
+      it { is_expected.to belong_to(:user) }
+      it { is_expected.to validate_presence_of(:user) }
+      it { is_expected.to validate_uniqueness_of(:user) }
+    end
+
+    describe "#comments_these_7_days" do
+      it "is valid if comments_these_7_days is an integer" do
+        counters.comments_these_7_days = 1
+        expect(counters).to be_valid
+      end
+
+      it "is is not if comments_these_7_days is not an integer" do
+        counters.comments_these_7_days = 1.2
+        expect(counters).not_to be_valid
+      end
+    end
+
+    describe "#comments_prior_7_days" do
+      it "is valid if comments_prior_7_days is an integer" do
+        counters.comments_prior_7_days = 1
+        expect(counters).to be_valid
+      end
+
+      it "is is not if comments_prior_7_days is not an integer" do
+        counters.comments_prior_7_days = 1.2
+        expect(counters).not_to be_valid
+      end
+    end
+  end
+end

spec/models/user_spec.rb

@@ -33,6 +33,7 @@ RSpec.describe User, type: :model do
       it { is_expected.to have_many(:chat_channels).through(:chat_channel_memberships) }
       it { is_expected.to have_many(:notification_subscriptions).dependent(:destroy) }
       it { is_expected.to have_one(:pro_membership).dependent(:destroy) }
+      it { is_expected.to have_one(:counters).dependent(:destroy) }
 
       # rubocop:disable RSpec/NamedSubject
       it "has created_podcasts" do