synchronize documents generation

lib/submissions/ensure_result_generated.rb

@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+module Submissions
+  module EnsureResultGenerated
+    WAIT_FOR_RETRY = 2.seconds
+    CHECK_EVENT_INTERVAL = 1.second
+    CHECK_COMPLETE_TIMEOUT = 20.seconds
+
+    WaitForCompleteTimeout = Class.new(StandardError)
+
+    module_function
+
+    def call(submitter)
+      return submitter.documents if submitter.document_generation_events.complete.exists?
+
+      events =
+        DocumentGenerationEvent.uncached do
+          DocumentGenerationEvent.where(submitter:).order(:created_at).to_a
+        end
+
+      if events.present? && events.last.event_name.in?(%w[start retry])
+        wait_for_complete_or_fail(submitter)
+      else
+        submitter.document_generation_events.create!(event_name: events.present? ? :retry : :start)
+
+        GenerateResultAttachments.call(submitter)
+
+        submitter.document_generation_events.create!(event_name: :complete)
+      end
+    rescue ActiveRecord::RecordNotUnique
+      sleep WAIT_FOR_RETRY
+
+      retry
+    rescue StandardError
+      submitter.document_generation_events.create!(event_name: :fail)
+
+      raise
+    end
+
+    def wait_for_complete_or_fail(submitter)
+      total_wait_time = 0
+
+      loop do
+        sleep CHECK_EVENT_INTERVAL
+        total_wait_time += CHECK_EVENT_INTERVAL
+
+        last_event =
+          DocumentGenerationEvent.uncached do
+            DocumentGenerationEvent.where(submitter:).order(:created_at).last
+          end
+
+        break last_event if last_event.event_name.in?(%w[complete fail])
+
+        raise WaitForCompleteTimeout if total_wait_time > CHECK_COMPLETE_TIMEOUT
+      end
+    end
+  end
+end

lib/submissions/generate_result_attachments.rb

@@ -209,9 +209,13 @@ module Submissions
     end
 
     def build_pdfs_index(submitter)
-      latest_submitter = submitter.submission.submitters
-                                  .select { |e| e.id != submitter.id && e.completed_at? }
-                                  .max_by(&:completed_at)
+      latest_submitter =
+        submitter.submission.submitters
+                 .select(&:completed_at?)
+                 .select { |e| e.id != submitter.id && e.completed_at <= submitter.completed_at }
+                 .max_by(&:completed_at)
+
+      Submissions::EnsureResultGenerated.call(latest_submitter) if latest_submitter
 
       documents   = latest_submitter&.documents&.preload(:blob).to_a.presence
       documents ||= submitter.submission.template.documents.preload(:blob)