Cache welcome thread query (forem#22741)

* Cache welcome thread query

* Fix query

* Fix private keyword

* Fix spec

Author: benhalpern

app/controllers/community_controller.rb

@@ -48,8 +48,8 @@ def index
     @key_pages = Page.where(subforem_id: RequestStore.store[:subforem_id]).where(is_top_level_path: true).limit(6)
 
     # Get welcome article if it exists
-    @welcome_article = Article.from_subforem.admin_published_with("welcome").first ||
-                       Article.admin_published_with("welcome").first
+    @welcome_article = Article.cached_admin_published_with("welcome", subforem_id: RequestStore.store[:subforem_id]) ||
+                       Article.cached_admin_published_with("welcome")
 
     set_surrogate_key_header "community_hub"
   end

app/controllers/pages_controller.rb

@@ -107,15 +107,15 @@ def robots
   end
 
   def welcome
-    article = Article.from_subforem.admin_published_with("welcome").first
-    article = Article.admin_published_with("welcome").first unless article
+    article = Article.cached_admin_published_with("welcome", subforem_id: RequestStore.store[:subforem_id])
+    article ||= Article.cached_admin_published_with("welcome")
     redirect_daily_thread_request(article)
   end
 
   def challenge
-    article = Article.from_subforem.admin_published_with("welcome").first
-    article = Article.admin_published_with("welcome").first unless article
-    redirect_daily_thread_request(Article.admin_published_with("challenge").first)
+    article = Article.cached_admin_published_with("welcome", subforem_id: RequestStore.store[:subforem_id])
+    article ||= Article.cached_admin_published_with("welcome")
+    redirect_daily_thread_request(Article.cached_admin_published_with("challenge"))
   end
 
   def checkin

app/models/article.rb

@@ -414,14 +414,38 @@ def self.unique_url_error
                           .union(User.with_role(:admin))
                           .union(id: [Settings::Community.staff_user_id,
                                       Settings::General.mascot_user_id].compact)
-                          .select(:id)).order(published_at: :desc).tagged_with(tag_name)
+                          .select(:id)).order(published_at: :desc).cached_tagged_with(tag_name)
   }
 
+  def self.cached_admin_published_with(tag_name, subforem_id: nil, expires_in: 6.hours)
+    cache_key = [
+      "admin-published-with",
+      tag_name,
+      (subforem_id || "all"),
+    ].join(":")
+
+    Rails.cache.fetch(cache_key, expires_in: expires_in) do
+      scope = subforem_id ? from_subforem(subforem_id) : all
+      scope.admin_published_with(tag_name).first
+    end
+  end
+
+  def self.bust_cached_admin_published_with(tag_name, subforem_id: nil)
+    cache_key = [
+      "admin-published-with",
+      tag_name,
+      (subforem_id || "all"),
+    ].join(":")
+    Rails.cache.delete(cache_key)
+  end
+
+  after_commit :bust_cached_admin_welcome_thread, on: %i[create update]
+
   scope :user_published_with, lambda { |user_id, tag_name|
     published
       .where(user_id: user_id)
       .order(published_at: :desc)
-      .tagged_with(tag_name)
+      .cached_tagged_with(tag_name)
   }
 
   scope :active_help, lambda {
@@ -1576,6 +1600,15 @@ def record_field_test_event
 
   private
 
+  def bust_cached_admin_welcome_thread
+    return unless published?
+    return unless cached_tag_list.to_s.match?(/(?:^|,)\s*welcome(?:\s*,|$)/)
+    return unless user&.admin?
+
+    self.class.bust_cached_admin_published_with("welcome", subforem_id: subforem_id)
+    self.class.bust_cached_admin_published_with("welcome")
+  end
+
   def should_add_urls_from_title?
     # Only add URLs from title for quickie posts (status type) that have a title with URLs
     # Only run this when the title has changed or it's a new record to avoid duplicating embed tags

app/services/broadcasts/welcome_notification/generator.rb

@@ -95,7 +95,7 @@ def received_notification?(broadcast)
       end
 
       def commented_on_welcome_thread?
-        welcome_thread = Article.admin_published_with("welcome").first
+        welcome_thread = Article.cached_admin_published_with("welcome")
         Comment.where(commentable: welcome_thread, user: user).any?
       end
 

app/services/scheduled_automations/warm_welcome_badge_awarder.rb

@@ -70,10 +70,10 @@ def find_current_welcome_thread
       # Try from subforem context if available, otherwise just get the most recent one
       subforem_id = RequestStore.store[:subforem_id] if defined?(RequestStore) && RequestStore.store
       if subforem_id
-        Article.from_subforem(subforem_id).admin_published_with("welcome").first ||
-          Article.admin_published_with("welcome").first
+        Article.cached_admin_published_with("welcome", subforem_id: subforem_id) ||
+          Article.cached_admin_published_with("welcome")
       else
-        Article.admin_published_with("welcome").first
+        Article.cached_admin_published_with("welcome")
       end
     end
 

app/views/onboardings/_task_card.html.erb

@@ -30,7 +30,7 @@
   <h2 class="task-card-title" id="task-card-title"><%= t("views.onboardings.heading") %></h2>
   <p id="task-card-subtitle" class="task-card-subtitle"><%= t("views.onboardings.subtitle") %></p>
   <ul class="task-card-actions">
-    <% if Article.admin_published_with("welcome").any? %>
+    <% if Article.cached_admin_published_with("welcome").present? %>
       <li class="task-card-action">
         <a class="task-card-link" href="/welcome">
           <p><%= t("views.onboardings.welcome_html") %></p>

spec/models/article_spec.rb

@@ -1634,6 +1634,95 @@ def build_and_validate_article(*args)
     end
   end
 
+  describe ".cached_admin_published_with" do
+    let(:admin) { create(:user, :admin) }
+    let(:cache_store) { ActiveSupport::Cache::MemoryStore.new }
+
+    around do |example|
+      original_cache = Rails.cache
+      Rails.cache = cache_store
+      example.run
+    ensure
+      Rails.cache = original_cache
+    end
+
+    it "caches the admin published article by tag" do
+      article = create(:article, user: admin, tags: "welcome")
+
+      cached = described_class.cached_admin_published_with("welcome")
+
+      expect(cached).to eq(article)
+      expect(Rails.cache.read("admin-published-with:welcome:all").id).to eq(article.id)
+    end
+
+    it "caches the admin published article by tag and subforem" do
+      subforem = create(:subforem)
+      article = create(:article, user: admin, tags: "welcome", subforem_id: subforem.id)
+
+      cached = described_class.cached_admin_published_with("welcome", subforem_id: subforem.id)
+
+      expect(cached).to eq(article)
+      expect(Rails.cache.read("admin-published-with:welcome:#{subforem.id}").id).to eq(article.id)
+    end
+  end
+
+  describe "admin welcome cache busting" do
+    let(:admin) { create(:user, :admin) }
+    let(:cache_store) { ActiveSupport::Cache::MemoryStore.new }
+
+    around do |example|
+      original_cache = Rails.cache
+      Rails.cache = cache_store
+      example.run
+    ensure
+      Rails.cache = original_cache
+    end
+
+    it "busts cached welcome keys when an admin publishes a welcome article" do
+      subforem = create(:subforem)
+      article = create(:article, user: admin, tags: "welcome", subforem_id: subforem.id)
+
+      Rails.cache.write("admin-published-with:welcome:all", "cached")
+      Rails.cache.write("admin-published-with:welcome:#{subforem.id}", "cached")
+
+      article.update!(title: "Updated title")
+
+      expect(Rails.cache.read("admin-published-with:welcome:all")).to be_nil
+      expect(Rails.cache.read("admin-published-with:welcome:#{subforem.id}")).to be_nil
+    end
+
+    it "does not bust cached welcome keys for non-admin authors" do
+      user = create(:user)
+      article = create(:article, user: user, tags: "welcome")
+
+      Rails.cache.write("admin-published-with:welcome:all", "cached")
+
+      article.update!(title: "Updated title")
+
+      expect(Rails.cache.read("admin-published-with:welcome:all")).to eq("cached")
+    end
+
+    it "busts the cache when welcome is in a comma-separated tag list" do
+      article = create(:article, user: admin, tags: "ruby, welcome, rails")
+
+      Rails.cache.write("admin-published-with:welcome:all", "cached")
+
+      article.update!(title: "Updated title")
+
+      expect(Rails.cache.read("admin-published-with:welcome:all")).to be_nil
+    end
+
+    it "does not bust the cache for tags that only contain welcome as a substring" do
+      article = create(:article, user: admin, tags: "welcome2, ruby")
+
+      Rails.cache.write("admin-published-with:welcome:all", "cached")
+
+      article.update!(title: "Updated title")
+
+      expect(Rails.cache.read("admin-published-with:welcome:all")).to eq("cached")
+    end
+  end
+
   describe ".seo_boostable" do
     let!(:top_article) do
       create(:article, organic_page_views_past_month_count: 20, score: 30, tags: "good, greatalicious", user: user)