Support tuning batch size of DB purge operation

The heat-manage purge_deleted command supports customizing batch size,
number of stacks to delete by a single transaction. This change adds
the new parameter to customize the parameter.

Change-Id: Id980c6f975f22baa305d3cd84378c98b3e9f84f2

manifests/cron/purge_deleted.pp

@@ -46,6 +46,10 @@
 #    (optional) Path to file to which rows should be archived
 #    Defaults to '/var/log/heat/heat-purge_deleted.log'.
 #
+#  [*batch_size*]
+#    (optional) Number of stacks to delete at a time (per transaction).
+#    Defaults to undef.
+#
 class heat::cron::purge_deleted (
   $ensure      = present,
   $minute      = 1,
@@ -57,7 +61,8 @@ class heat::cron::purge_deleted (
   $user        = $::heat::params::user,
   $age         = 1,
   $age_type    = 'days',
-  $destination = '/var/log/heat/heat-purge_deleted.log'
+  $destination = '/var/log/heat/heat-purge_deleted.log',
+  $batch_size  = undef,
 ) inherits heat::params {
 
   if ! member(['days', 'hours', 'minutes', 'seconds'], $age_type) {
@@ -70,9 +75,15 @@ class heat::cron::purge_deleted (
     $sleep = "sleep `expr \${RANDOM} \\% ${maxdelay}`; "
   }
 
+  if $batch_size != undef {
+    $batch_size_opt = "-b ${batch_size} "
+  } else {
+    $batch_size_opt = ''
+  }
+
   cron { 'heat-manage purge_deleted':
     ensure      => $ensure,
-    command     => "${sleep}heat-manage purge_deleted -g ${age_type} ${age} >>${destination} 2>&1",
+    command     => "${sleep}heat-manage purge_deleted -g ${age_type} ${age} ${batch_size_opt}>>${destination} 2>&1",
     environment => 'PATH=/bin:/usr/bin:/usr/sbin SHELL=/bin/sh',
     user        => $user,
     minute      => $minute,

releasenotes/notes/purge-batch_size-12871727027b7357.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    The ``heat::cron::purge_deleted`` class now supports customizing batch size
+    of the purge operation.

spec/classes/heat_cron_purge_deleted_spec.rb

@@ -64,6 +64,29 @@ describe 'heat::cron::purge_deleted' do
       end
     end
 
+    describe 'when batch_size is set' do
+      before :each do
+        params.merge!(
+          :batch_size => 100
+        )
+      end
+
+      it 'disables the cron job' do
+        is_expected.to contain_cron('heat-manage purge_deleted').with(
+          :ensure      => params[:ensure],
+          :command     => "heat-manage purge_deleted -g days 1 -b #{params[:batch_size]} >>#{params[:destination]} 2>&1",
+          :environment => 'PATH=/bin:/usr/bin:/usr/sbin SHELL=/bin/sh',
+          :user        => 'heat',
+          :minute      => params[:minute],
+          :hour        => params[:hour],
+          :monthday    => params[:monthday],
+          :month       => params[:month],
+          :weekday     => params[:weekday],
+          :require     => 'Anchor[heat::dbsync::end]'
+        )
+      end
+    end
+
     describe 'when disabling cron job' do
       before :each do
         params.merge!(