Bound native fragment caching and collapse concurrent page renders

test/controllers/fragment_cache_test.rb

@@ -0,0 +1,125 @@
+require "test_helper"
+
+class FragmentRenderingTest < ActionDispatch::IntegrationTest
+  self.use_transactional_tests = false
+
+  setup do
+    host! "once.campfire.test"
+    sign_in :david
+    @previous_caching = ActionController::Base.perform_caching
+    @previous_message_caching = MessagesController.perform_caching
+    @class_store = ApplicationController.cache_store
+    @global_store = Rails.cache
+    ActionController::Base.perform_caching = true
+    MessagesController.perform_caching = true
+    FragmentCache.store.clear
+    ResponseCache.instance.clear
+    @room = rooms(:watercooler)
+    @message = @room.messages.ordered.last
+  end
+
+  teardown do
+    ActionController::Base.perform_caching = @previous_caching
+    MessagesController.perform_caching = @previous_message_caching
+    FragmentCache.store.clear
+    ResponseCache.instance.clear
+  end
+
+  test "native collection caching uses the bounded store without replacing shared stores" do
+    assert_same FragmentCache.store, ApplicationController.new.cache_store
+    assert_same FragmentCache.store, ActionView::PartialRenderer.collection_cache
+    assert_same @class_store, ApplicationController.cache_store
+    assert_same @global_store, Rails.cache
+    ResponseCache.instance.stubs(:budget).returns(0)
+    get room_messages_url(@room)
+    assert_response :success
+    hits = []
+    ActiveSupport::Notifications.subscribed(->(event) { hits.concat(event.payload[:hits]) }, "cache_read_multi.active_support") do
+      get room_messages_url(@room)
+    end
+    assert_response :success
+    assert_not_empty hits
+  end
+
+  test "disabled page caching retains fresh native fragments after foreign leaf writes" do
+    ResponseCache.instance.stubs(:budget).returns(0)
+    get room_messages_url(@room)
+    assert_response :success
+    foreign_write("UPDATE action_text_rich_texts SET body = ? WHERE record_type = 'Message' AND record_id = ?", "foreign disabled body", @message.id)
+    get room_messages_url(@room)
+    assert_response :success
+    assert_includes response.body, "foreign disabled body"
+  end
+
+  test "conditional pagination invalidates warmed native fragments without timestamp changes" do
+    get room_messages_url(@room), headers: { "If-None-Match" => "unmatched" }
+    assert_response :success
+    etag = response.headers["ETag"]
+    foreign_write("UPDATE action_text_rich_texts SET body = ? WHERE record_type = 'Message' AND record_id = ?", "foreign conditional body", @message.id)
+    get room_messages_url(@room), headers: { "If-None-Match" => etag }
+    assert_response :success
+    assert_includes response.body, "foreign conditional body"
+  end
+
+  test "refresh streams recheck native cached creator body and boost presentation" do
+    message = messages(:first)
+    room = message.room
+    get room_refresh_url(room, format: :turbo_stream), params: { since: 0 }
+    assert_response :success
+    foreign_write("UPDATE action_text_rich_texts SET body = ? WHERE record_type = 'Message' AND record_id = ?", "foreign refreshed body", message.id)
+    foreign_write("UPDATE users SET name = ? WHERE id = ?", "Foreign refreshed creator", message.creator_id)
+    foreign_write("UPDATE boosts SET content = ? WHERE message_id = ?", "Foreign refreshed boost", message.id)
+    get room_refresh_url(room, format: :turbo_stream), params: { since: 0 }
+    assert_response :success
+    assert_includes response.body, "foreign refreshed body"
+    assert_includes response.body, "Foreign refreshed creator"
+    assert_includes response.body, "Foreign refreshed boost"
+  end
+
+  test "Jbuilder fragments use the bounded store and do not create HTML token state" do
+    api = open_session { |session| session.host! "once.campfire.test" }
+    path = room_bot_messages_path(@room, users(:bender).bot_key)
+    api.get path
+    assert_equal 200, api.response.status
+    assert_not api.cookies["_campfire_session"]
+    hits = []
+    ActiveSupport::Notifications.subscribed(->(event) { hits << event.payload[:key] if event.payload[:hit] }, "cache_read.active_support") do
+      api.get path
+    end
+    assert_equal 200, api.response.status
+    assert_not_empty hits
+    foreign_write("UPDATE action_text_rich_texts SET body = ? WHERE record_type = 'Message' AND record_id = ?", "foreign JSON body", @message.id)
+    foreign_write("UPDATE users SET name = ? WHERE id = ?", "Foreign JSON creator", @message.creator_id)
+    api.get path
+    json = JSON.parse(api.response.body).find { |message| message["id"] == @message.id }
+    assert_includes json.dig("body", "html"), "foreign JSON body"
+    assert_equal "Foreign JSON creator", json.dig("creator", "name")
+    api.host! "another.campfire.test:8081"
+    api.get path
+    json = JSON.parse(api.response.body).find { |message| message["id"] == @message.id }
+    assert_includes json["url"], "another.campfire.test:8081"
+    assert_same @global_store, Rails.cache
+  end
+
+  test "detached broadcasts bypass fragments without a pre-render model snapshot" do
+    get room_messages_url(@room)
+    foreign_write("UPDATE action_text_rich_texts SET body = ? WHERE record_type = 'Message' AND record_id = ?", "foreign broadcast body", @message.id)
+    FragmentCache.store.expects(:read).never
+    FragmentCache.store.expects(:write).never
+    @message.reload.broadcast_create
+    assert_rendered_turbo_stream_broadcast @room, :messages, action: "append", target: [ @room, :messages ] do |stream|
+      assert_includes stream.to_html, "foreign broadcast body"
+    end
+    body = ApplicationController.render(partial: "messages/message", locals: { message: @message.reload })
+    assert_includes body, "foreign broadcast body"
+    assert_not ApplicationController.new.perform_caching
+  end
+
+  private
+    def foreign_write(sql, *bindings)
+      SQLite3::Database.new(ActiveRecord::Base.connection_db_config.database) do |database|
+        database.execute(sql, bindings)
+      end
+      ActiveRecord::Base.clear_query_caches_for_current_thread
+    end
+end

test/models/response_cache_test.rb

@@ -44,12 +44,43 @@ class ResponseCacheTest < ActiveSupport::TestCase
     assert_nil @cache.read("k" * 2049, version)
   end
 
-  test "observer namespaces cannot reuse old shared fragment keys after restart" do
+  test "clearing the observer gives later pages a distinct namespace" do
     version = @cache.version
     @cache.clear
     assert_not_equal version, @cache.version
   end
 
+  test "cold renders coalesce without holding the observer mutex" do
+    version = @cache.version
+    entered = Queue.new
+    release = Queue.new
+    first = Thread.new do
+      @cache.synchronize_render("page", version) do
+        entered << true
+        release.pop
+        @cache.write("page", version, entry("completed render"))
+      end
+    end
+    entered.pop
+    second_started = Queue.new
+    second = Thread.new do
+      second_started << true
+      @cache.synchronize_render("page", version) { @cache.read("page", version) }
+    end
+    second_started.pop
+    deadline = Process.clock_gettime(Process::CLOCK_MONOTONIC) + 2
+    Thread.pass until second.status == "sleep" || Process.clock_gettime(Process::CLOCK_MONOTONIC) >= deadline
+    assert_equal "sleep", second.status
+    assert_nil @cache.read("page", version)
+    assert_equal version, @cache.version
+    release << true
+    first.value
+    assert_equal "completed render", second.value[:body]
+  ensure
+    release << true if release
+    [ first, second ].compact.each { |thread| thread.join(2) }
+  end
+
   private
     def entry(body)
       { body: body, marker: "unexposed-marker", headers: {} }