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.

13 files changed, 87 insertions, 32 deletions

diff --git a/app/models/issue.rb b/app/models/issue.rb
index 7bfc45c1f43..f65cd8bf896 100644
--- a/app/models/issue.rb
+++ b/app/models/issue.rb
@@ -48,6 +48,7 @@ class Issue < ActiveRecord::Base
   scope :without_due_date, -> { where(due_date: nil) }
   scope :due_before, ->(date) { where('issues.due_date < ?', date) }
   scope :due_between, ->(from_date, to_date) { where('issues.due_date >= ?', from_date).where('issues.due_date <= ?', to_date) }
+  scope :due_tomorrow, -> { where(due_date: Date.tomorrow) }
 
   scope :order_due_date_asc, -> { reorder('issues.due_date IS NULL, issues.due_date ASC') }
   scope :order_due_date_desc, -> { reorder('issues.due_date IS NULL, issues.due_date DESC') }
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
diff --git a/changelogs/unreleased/16957-issue-due-email.yml b/changelogs/unreleased/16957-issue-due-email.yml
index 308f72e6a67..83944ca4f73 100644
--- a/changelogs/unreleased/16957-issue-due-email.yml
+++ b/changelogs/unreleased/16957-issue-due-email.yml
@@ -1,5 +1,5 @@
 ---
 title: Add cron job to email users on issue due date
-merge_request: 16957
+merge_request: 17985
 author: Stuart Nelson
 type: added
diff --git a/config/initializers/1_settings.rb b/config/initializers/1_settings.rb
index 1ddf380c56d..c8a4c1af50f 100644
--- a/config/initializers/1_settings.rb
+++ b/config/initializers/1_settings.rb
@@ -453,9 +453,9 @@ Settings.cron_jobs['pages_domain_verification_cron_worker'] ||= Settingslogic.ne
 Settings.cron_jobs['pages_domain_verification_cron_worker']['cron'] ||= '*/15 * * * *'
 Settings.cron_jobs['pages_domain_verification_cron_worker']['job_class'] = 'PagesDomainVerificationCronWorker'
 
-Settings.cron_jobs['issue_due_worker'] ||= Settingslogic.new({})
-Settings.cron_jobs['issue_due_worker']['cron'] ||= '50 00 * * *'
-Settings.cron_jobs['issue_due_worker']['job_class'] = 'IssueDueWorker'
+Settings.cron_jobs['issue_due_scheduler_worker'] ||= Settingslogic.new({})
+Settings.cron_jobs['issue_due_scheduler_worker']['cron'] ||= '50 00 * * *'
+Settings.cron_jobs['issue_due_scheduler_worker']['job_class'] = 'IssueDueSchedulerWorker'
 
 #
 # GitLab Shell
diff --git a/config/sidekiq_queues.yml b/config/sidekiq_queues.yml
index c811034b29d..47fbbed44cf 100644
--- a/config/sidekiq_queues.yml
+++ b/config/sidekiq_queues.yml
@@ -34,6 +34,7 @@
   - [email_receiver, 2]
   - [emails_on_push, 2]
   - [mailers, 2]
+  - [mail_scheduler, 2]
   - [invalid_gpg_signature_update, 2]
   - [create_gpg_signature, 2]
   - [rebase, 2]
diff --git a/doc/user/project/issues/due_dates.md b/doc/user/project/issues/due_dates.md
index e0c405353ce..400f581e513 100644
--- a/doc/user/project/issues/due_dates.md
+++ b/doc/user/project/issues/due_dates.md
@@ -35,5 +35,8 @@ Due dates also appear in your [todos list](../../../workflow/todos.md).
 
 ![Issues with due dates in the todos](img/due_dates_todos.png)
 
+The day before an open issue is due, an email will be sent to all participants
+of the issue.
+
 [ce-3614]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/3614
 [permissions]: ../../permissions.md#project
diff --git a/spec/workers/issue_due_scheduler_worker_spec.rb b/spec/workers/issue_due_scheduler_worker_spec.rb
new file mode 100644
index 00000000000..eff5855834c
--- /dev/null
+++ b/spec/workers/issue_due_scheduler_worker_spec.rb
@@ -0,0 +1,23 @@
+require 'spec_helper'
+
+describe IssueDueSchedulerWorker do
+  describe '#perform' do
+    it 'schedules one MailScheduler::IssueDueWorker per project with open issues due tomorrow' do
+      project1 = create(:project)
+      project2 = create(:project)
+      project_closed_issue = create(:project)
+      project_issue_due_another_day = create(:project)
+
+      create(:issue, :opened, project: project1, due_date: Date.tomorrow)
+      create(:issue, :opened, project: project1, due_date: Date.tomorrow)
+      create(:issue, :opened, project: project2, due_date: Date.tomorrow)
+      create(:issue, :closed, project: project_closed_issue, due_date: Date.tomorrow)
+      create(:issue, :opened, project: project_issue_due_another_day, due_date: Date.today)
+
+      expect(MailScheduler::IssueDueWorker).to receive(:perform_async).with(project1.id)
+      expect(MailScheduler::IssueDueWorker).to receive(:perform_async).with(project2.id)
+
+      described_class.new.perform
+    end
+  end
+end
diff --git a/spec/workers/issue_due_worker_spec.rb b/spec/workers/issue_due_worker_spec.rb
deleted file mode 100644
index 9004edbee3a..00000000000
--- a/spec/workers/issue_due_worker_spec.rb
+++ /dev/null
@@ -1,17 +0,0 @@
-require 'spec_helper'
-
-describe IssueDueWorker do
-  describe 'perform' do
-    let(:worker) { described_class.new }
-
-    it 'finds issues due on the day run' do
-      issue1 = create(:issue, :opened, due_date: Date.today)
-      create(:issue, :opened, due_date: 3.days.from_now)
-      create(:issue, :opened, due_date: 4.days.from_now)
-
-      expect_any_instance_of(NotificationService).to receive(:issue_due_email).with(issue1)
-
-      worker.perform
-    end
-  end
-end
diff --git a/spec/workers/mail_scheduler/issue_due_worker_spec.rb b/spec/workers/mail_scheduler/issue_due_worker_spec.rb
new file mode 100644
index 00000000000..48ac1b8a1a4
--- /dev/null
+++ b/spec/workers/mail_scheduler/issue_due_worker_spec.rb
@@ -0,0 +1,21 @@
+require 'spec_helper'
+
+describe MailScheduler::IssueDueWorker do
+  describe '#perform' do
+    let(:worker) { described_class.new }
+    let(:project) { create(:project) }
+
+    it 'sends emails for open issues due tomorrow in the project specified' do
+      issue1 = create(:issue, :opened, project: project, due_date: Date.tomorrow)
+      issue2 = create(:issue, :opened, project: project, due_date: Date.tomorrow)
+      create(:issue, :closed, project: project, due_date: Date.tomorrow) # closed
+      create(:issue, :opened, project: project, due_date: 2.days.from_now) # due on another day
+      create(:issue, :opened, due_date: Date.tomorrow) # different project
+
+      expect_any_instance_of(NotificationService).to receive(:issue_due).with(issue1)
+      expect_any_instance_of(NotificationService).to receive(:issue_due).with(issue2)
+
+      worker.perform(project.id)
+    end
+  end
+end