scrub old conversation batches

refs CORE-123

Change-Id: Id3181523ffbd574a1cbf4a92aad4999b2d09b3e8
Reviewed-on: https://gerrit.instructure.com/134279
Tested-by: Jenkins
Reviewed-by: Rob Orton <rob@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>

config/initializers/periodic_jobs.rb

@@ -143,6 +143,10 @@ Rails.configuration.after_initialize do
     with_each_shard_by_database(DelayedMessageScrubber, :scrub)
   end
 
+  Delayed::Periodic.cron 'ConversationBatchScrubber.scrub_all', '0 2 * * *' do
+    with_each_shard_by_database(ConversationBatchScrubber, :scrub)
+  end
+
   Delayed::Periodic.cron 'BounceNotificationProcessor.process', '*/5 * * * *' do
     DatabaseServer.send_in_each_region(
       BounceNotificationProcessor,

lib/conversation_batch_scrubber.rb

@@ -0,0 +1,39 @@
+#
+# Copyright (C) 2017 - present Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+
+# Public: Delete old (> 90 days) records from conversation_batches table.
+class ConversationBatchScrubber < MessageScrubber
+
+  protected
+
+  def filter_attribute
+    'updated_at'
+  end
+
+  def klass
+    ConversationBatch.where(workflow_state: 'sent')
+  end
+
+  def limit_setting
+    'conversation_batch_scrubber_limit'
+  end
+
+  def limit_size
+    90
+  end
+end