DEV: Refactor ApplicationHelper#server_plugin_outlet take 2 (#36418)

Take 1 reverted in
https://github.com/discourse/discourse/commit/dc97318ad12c16d28d2e80b944278aaed2c10d24
as it ended up causing a memory leak.

app/helpers/application_helper.rb

@@ -516,40 +516,42 @@ module ApplicationHelper
     CategoryBadge.html_for(category, opts).html_safe
   end
 
-  def self.all_connectors
-    @all_connectors = Dir.glob("plugins/*/app/views/connectors/**/*.html.erb")
+  SERVER_PLUGIN_OUTLET_PLUGINS_PREFIXES = [Rails.root.join("plugins/").to_s]
+  private_constant :SERVER_PLUGIN_OUTLET_PLUGINS_PREFIXES
+
+  if Rails.env.test?
+    SERVER_PLUGIN_OUTLET_PLUGINS_PREFIXES << Rails.root.join("spec/fixtures/plugins/").to_s
   end
 
-  PLUGIN_OUTLET_TEMPLATE_CACHE = Concurrent::Map.new
+  SERVER_PLUGIN_OUTLET_CONNECTOR_TEMPLATES =
+    SERVER_PLUGIN_OUTLET_PLUGINS_PREFIXES.each_with_object({}) do |plugins_prefix, connectors|
+      Dir
+        .glob("#{plugins_prefix}*/app/views/connectors/**/*.html.erb")
+        .each do |template_path|
+          template_path =~ Regexp.new("/connectors/(.*)/.*\.html\.erb$")
+          outlet_name = Regexp.last_match(1)
+          connectors[outlet_name] ||= []
+
+          connectors[outlet_name] << begin
+            ActionView::Template.new(
+              File.read(template_path),
+              "discourse_plugin_outlet__#{name}",
+              ActionView::Template.handler_for_extension("erb"),
+              locals: [],
+              format: :html,
+              virtual_path: template_path,
+            )
+          end
+        end
+    end
+  private_constant :SERVER_PLUGIN_OUTLET_CONNECTOR_TEMPLATES
 
   def server_plugin_outlet(name, locals: {})
     return "" if !GlobalSetting.load_plugins?
+    return "" if !SERVER_PLUGIN_OUTLET_CONNECTOR_TEMPLATES.key?(name)
 
-    matcher = Regexp.new("/connectors/#{name}/.*\.html\.erb$")
-    erbs = ApplicationHelper.all_connectors.select { |c| c =~ matcher }
-    return "" if erbs.blank?
-
-    erbs
-      .map do |erb|
-        cache_key = [erb, locals.keys.sort]
-
-        template =
-          PLUGIN_OUTLET_TEMPLATE_CACHE.compute_if_absent(cache_key) do
-            source = File.read(erb)
-            handler = ActionView::Template.handler_for_extension("erb")
-
-            ActionView::Template.new(
-              source,
-              "discourse_plugin_outlet__#{name}",
-              handler,
-              locals: locals.keys,
-              format: :html,
-              virtual_path: erb,
-            )
-          end
-
-        render template: template, locals: locals
-      end
+    SERVER_PLUGIN_OUTLET_CONNECTOR_TEMPLATES[name]
+      .map { |template| render template:, locals: }
       .join
       .html_safe
   end

config/initializers/development.rb

@@ -1,5 +0,0 @@
-# frozen_string_literal: true
-
-if Rails.env.development?
-  Rails.application.reloader.to_prepare { ApplicationHelper::PLUGIN_OUTLET_TEMPLATE_CACHE.clear }
-end

spec/fixtures/plugins/my_plugin/app/views/connectors/topic_header/template_1.html.erb

@@ -0,0 +1 @@
+Fixture from my_plugin template 1: <%= @topic_view.topic.title %>

spec/fixtures/plugins/my_plugin/app/views/connectors/topic_header/template_2.html.erb

@@ -0,0 +1 @@
+Fixture from my_plugin template 2: <%= @topic_view.topic.title %>

spec/fixtures/plugins/my_plugin_2/app/views/connectors/topic_header/template_1.html.erb

@@ -0,0 +1 @@
+Fixture from my_plugin_2 template 1: <%= @topic_view.topic.title %>

spec/fixtures/plugins/my_plugin_2/app/views/connectors/topic_header/template_2.html.erb

@@ -0,0 +1 @@
+Fixture from my_plugin_2 template 2: <%= @topic_view.topic.title %>

spec/fixtures/plugins/my_plugin_3/app/views/connectors/some_other_outlet/template_1.html.erb

@@ -0,0 +1 @@
+Fixture from my_plugin_3 template 1: <%= @topic_view.topic.title %>

spec/requests/topics_controller_spec.rb

@@ -40,34 +40,35 @@ RSpec.describe TopicsController do
   describe "topic_header plugin outlet" do
     fab!(:another_topic) { Fabricate(:topic, title: "Another topic by me") }
 
-    let(:tmp_dir) { Dir.mktmpdir }
-    let(:template_dir) do
-      path = File.join(tmp_dir, "connectors", "topic_header")
-      FileUtils.mkdir_p(path)
-      path
-    end
-    let(:template_file) do
-      file = Tempfile.new(%w[test_template .html.erb], template_dir)
-      file.write("Topic title from outlet: <%= @topic_view.topic.title %>")
-      file.close
-      file
-    end
+    before { global_setting(:load_plugins?, true) }
 
-    before do
-      global_setting(:load_plugins?, true)
-      ApplicationHelper.stubs(:all_connectors).returns([template_file.path])
-    end
-
-    after { FileUtils.remove_entry(tmp_dir) if tmp_dir }
-
-    it "doesn't leak state between requests" do
+    it "renders the connector templates from multiple plugins" do
       get "/t/#{topic.slug}/#{topic.id}"
+
       expect(response.status).to eq(200)
-      expect(response.body).to include("Topic title from outlet: #{topic.title}")
+      expect(response.body).to include("Fixture from my_plugin template 1: #{topic.title}")
+      expect(response.body).to include("Fixture from my_plugin template 2: #{topic.title}")
+      expect(response.body).to include("Fixture from my_plugin_2 template 1: #{topic.title}")
+      expect(response.body).to include("Fixture from my_plugin_2 template 2: #{topic.title}")
+      expect(response.body).not_to include("Fixture from my_plugin_3 template 1: #{topic.title}")
 
       get "/t/#{another_topic.slug}/#{another_topic.id}"
+
       expect(response.status).to eq(200)
-      expect(response.body).to include("Topic title from outlet: #{another_topic.title}")
+      expect(response.body).to include("Fixture from my_plugin template 1: #{another_topic.title}")
+      expect(response.body).to include("Fixture from my_plugin template 2: #{another_topic.title}")
+
+      expect(response.body).to include(
+        "Fixture from my_plugin_2 template 1: #{another_topic.title}",
+      )
+
+      expect(response.body).to include(
+        "Fixture from my_plugin_2 template 2: #{another_topic.title}",
+      )
+
+      expect(response.body).not_to include(
+        "Fixture from my_plugin_3 template 1: #{another_topic.title}",
+      )
     end
   end