Have doubled workers for keystone service

Since we have merged 2 keystone services(public and admin) into one,
we need to double keystone workers so that we have the same number of
workers, which is necessory to avoid performance degradation.

This patch introduced new facter, os_workers_keystone, which returns
2 x os_workers .

Change-Id: I737fb14739a69ac12c39c7faf6dd2be1f772daa6
(cherry picked from commit 74e0f5a317)

lib/facter/os_workers.rb

@@ -61,3 +61,16 @@ Facter.add(:os_workers_heat_engine) do
     [ [ (processors.to_i / 2), 4 ].max, 24 ].min
   end
 end
+
+#
+# Since we have merged keystone admin and keystone public into a single
+# keystone instance, we need doubled workers to have the same number
+# of workers in total to avoid performance degradation.
+#
+Facter.add(:os_workers_keystone) do
+  has_weight 100
+  setcode do
+    processors = Facter.value('processorcount')
+    [ [ processors.to_i, 4 ].max, 24 ].min
+  end
+end

spec/unit/facter/os_workers_keystone_spec.rb

@@ -0,0 +1,36 @@
+require 'spec_helper'
+
+describe 'os_workers_keystone' do
+
+  before { Facter.flush }
+
+  context 'with processorcount=1' do
+    before do
+      Facter.fact(:processorcount).stubs(:value).returns(1)
+    end
+
+    it 'returns a minimum of 4' do
+      expect(Facter.fact(:os_workers_keystone).value).to eq(4)
+    end
+  end
+
+  context 'with processorcount=8' do
+    before do
+      Facter.fact(:processorcount).stubs(:value).returns(8)
+    end
+
+    it 'returns processorcount' do
+      expect(Facter.fact(:os_workers_keystone).value).to eq(8)
+    end
+  end
+
+  context 'with processorcount=32' do
+    before do
+      Facter.fact(:processorcount).stubs(:value).returns(32)
+    end
+
+    it 'returns a maximum of 24' do
+      expect(Facter.fact(:os_workers_keystone).value).to eq(24)
+    end
+  end
+end