Send emails for issues due tomorrow

Also, refactor the mail sending slightly: instead of one worker sending all
emails, create a worker per project with issues due, which will send all emails
for that project.

5 files changed, 34 insertions, 11 deletions

diff --git a/app/workers/all_queues.yml b/app/workers/all_queues.yml
index ef445055f6e..9aea3bad27b 100644
--- a/app/workers/all_queues.yml
+++ b/app/workers/all_queues.yml
@@ -18,7 +18,7 @@
 - cronjob:stuck_import_jobs
 - cronjob:stuck_merge_jobs
 - cronjob:trending_projects
-- cronjob:issue_due
+- cronjob:issue_due_scheduler
 
 - gcp_cluster:cluster_install_app
 - gcp_cluster:cluster_provision
@@ -40,6 +40,8 @@
 - github_importer:github_import_stage_import_pull_requests
 - github_importer:github_import_stage_import_repository
 
+- mail_scheduler:mail_scheduler_issue_due
+
 - object_storage_upload
 - object_storage:object_storage_background_move
 - object_storage:object_storage_migrate_uploads
diff --git a/app/workers/concerns/mail_scheduler_queue.rb b/app/workers/concerns/mail_scheduler_queue.rb
new file mode 100644
index 00000000000..9df55ad9522
--- /dev/null
+++ b/app/workers/concerns/mail_scheduler_queue.rb
@@ -0,0 +1,7 @@
+module MailSchedulerQueue
+  extend ActiveSupport::Concern
+
+  included do
+    queue_namespace :mail_scheduler
+  end
+end
diff --git a/app/workers/issue_due_scheduler_worker.rb b/app/workers/issue_due_scheduler_worker.rb
new file mode 100644
index 00000000000..9c06304bff6
--- /dev/null
+++ b/app/workers/issue_due_scheduler_worker.rb
@@ -0,0 +1,10 @@
+class IssueDueSchedulerWorker
+  include ApplicationWorker
+  include CronjobQueue
+
+  def perform
+    Issue.opened.due_tomorrow.group(:project_id).pluck(:project_id).each do |project_id|
+      MailScheduler::IssueDueWorker.perform_async(project_id)
+    end
+  end
+end
diff --git a/app/workers/issue_due_worker.rb b/app/workers/issue_due_worker.rb
deleted file mode 100644
index 90d2cc09f1b..00000000000
--- a/app/workers/issue_due_worker.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-class IssueDueWorker
-  include ApplicationWorker
-  include CronjobQueue
-
-  def perform
-    Issue.where(due_date: Date.today).find_each do |issue|
-      NotificationService.new.issue_due_email(issue)
-    end
-  end
-end
diff --git a/app/workers/mail_scheduler/issue_due_worker.rb b/app/workers/mail_scheduler/issue_due_worker.rb
new file mode 100644
index 00000000000..b06079d68ca
--- /dev/null
+++ b/app/workers/mail_scheduler/issue_due_worker.rb
@@ -0,0 +1,14 @@
+module MailScheduler
+  class IssueDueWorker
+    include ApplicationWorker
+    include MailSchedulerQueue
+
+    def perform(project_id)
+      notification_service = NotificationService.new
+
+      Issue.opened.due_tomorrow.in_projects(project_id).preload(:project).find_each do |issue|
+        notification_service.issue_due(issue)
+      end
+    end
+  end
+end