From a7749d663f6de73984fb17b9b1c30f827c6feeb4 Mon Sep 17 00:00:00 2001
From: Ryan Lue <hello@ryanlue.com>
Date: Fri, 20 Jul 2018 13:08:26 +0800
Subject: [PATCH] Handle race condition when calling ActivityStream#assets
 (fixes #2066)

---
 lib/sessions/backend/activity_stream.rb       |  7 +++++-
 .../sessions/backend/activity_stream_spec.rb  | 24 +++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 spec/lib/sessions/backend/activity_stream_spec.rb

diff --git a/lib/sessions/backend/activity_stream.rb b/lib/sessions/backend/activity_stream.rb
index 4ec3e5abf..fbea4557f 100644
--- a/lib/sessions/backend/activity_stream.rb
+++ b/lib/sessions/backend/activity_stream.rb
@@ -31,8 +31,13 @@ class Sessions::Backend::ActivityStream
     assets = {}
     item_ids = []
     activity_stream.each do |item|
+      begin
+        assets = item.assets(assets)
+      rescue ActiveRecord::RecordNotFound
+        next
+      end
+
       item_ids.push item.id
-      assets = item.assets(assets)
     end
 
     {
diff --git a/spec/lib/sessions/backend/activity_stream_spec.rb b/spec/lib/sessions/backend/activity_stream_spec.rb
new file mode 100644
index 000000000..071cc28fd
--- /dev/null
+++ b/spec/lib/sessions/backend/activity_stream_spec.rb
@@ -0,0 +1,24 @@
+require 'rails_helper'
+
+RSpec.describe Sessions::Backend::ActivityStream do
+  context 'when async processes affect associated objects / DB records (#2066)' do
+    let(:subject)            { described_class.new(user, {}) }
+    let(:user)               { create(:agent_user, groups: [group]) }
+    let(:group)              { Group.find_by(name: 'Users') }
+    let(:associated_tickets) { create_list(:ticket, ticket_count, group: group) }
+    let(:ticket_count)       { 20 }
+
+    before do
+      Setting.set('system_init_done', true)
+
+      # these records must be created before the example begins
+      # (same as `let!`, but harder to miss)
+      associated_tickets
+    end
+
+    it 'manages race condition' do
+      Thread.new { associated_tickets.each(&:destroy) }
+      expect { subject.load }.not_to raise_error
+    end
+  end
+end