Added total query time to Sherlock

This makes it easier to see if a problem is caused by slow queries or
slow Ruby code (unrelated to any SQL queries that might be used).

app/views/sherlock/transactions/_general.html.haml

@@ -25,6 +25,12 @@
         %strong
           = @transaction.duration.round(2)
           = t('sherlock.seconds')
+      %li
+        %span.light
+          #{t('sherlock.query_time')}
+        %strong
+          = @transaction.query_duration.round(2)
+          = t('sherlock.seconds')
       %li
         %span.light
           #{t('sherlock.finished_at')}:

config/locales/sherlock.en.yml

@@ -35,3 +35,4 @@ en:
     events: Events
     percent: '%'
     count: Count
+    query_time: Query Time

lib/gitlab/sherlock/transaction.rb

@@ -36,6 +36,11 @@ module Gitlab
         @duration ||= started_at && finished_at ? finished_at - started_at : 0
       end
+      # Returns the total query duration in seconds.
+      def query_duration
+        @query_duration ||= @queries.map { |q| q.duration }.inject(:+) / 1000.0
+      end
+
       def to_param
         @id
       end

spec/lib/gitlab/sherlock/transaction_spec.rb

@@ -84,6 +84,19 @@ describe Gitlab::Sherlock::Transaction do
     end
   end
+  describe '#query_duration' do
+    it 'returns the total query duration in seconds' do
+      time   = Time.now
+      query1 = Gitlab::Sherlock::Query.new('SELECT 1', time, time + 5)
+      query2 = Gitlab::Sherlock::Query.new('SELECT 2', time, time + 2)
+
+      transaction.queries << query1
+      transaction.queries << query2
+
+      expect(transaction.query_duration).to be_within(0.1).of(7.0)
+    end
+  end
+
   describe '#to_param' do
     it 'returns the transaction ID' do
       expect(transaction.to_param).to eq(transaction.id)