Add start time to Gitaly items in the performance bar

Issue https://gitlab.com/groups/gitlab-org/-/epics/5590

lib/gitlab/gitaly_client/call.rb

@@ -50,11 +50,11 @@ module Gitlab
       end
 
       def recording_request
-        start = Gitlab::Metrics::System.monotonic_time
+        @start = Gitlab::Metrics::System.monotonic_time
 
         yield
       ensure
-        @duration += Gitlab::Metrics::System.monotonic_time - start
+        @duration += Gitlab::Metrics::System.monotonic_time - @start
       end
 
       def store_timings
@@ -64,8 +64,14 @@ module Gitlab
 
         request_hash = @request.is_a?(Google::Protobuf::MessageExts) ? @request.to_h : {}
 
-        GitalyClient.add_call_details(feature: "#{@service}##{@rpc}", duration: @duration, request: request_hash, rpc: @rpc,
-                                      backtrace: Gitlab::BacktraceCleaner.clean_backtrace(caller))
+        GitalyClient.add_call_details(
+          start: @start,
+          feature: "#{@service}##{@rpc}",
+          duration: @duration,
+          request: request_hash,
+          rpc: @rpc,
+          backtrace: Gitlab::BacktraceCleaner.clean_backtrace(caller)
+        )
       end
     end
   end

spec/lib/gitlab/gitaly_client/call_spec.rb

@@ -24,11 +24,14 @@ RSpec.describe Gitlab::GitalyClient::Call do
     def expect_call_details_to_match(duration_higher_than: 0)
       expect(client.list_call_details.size).to eq(1)
       expect(client.list_call_details.first)
-        .to match a_hash_including(feature: "#{service}##{rpc}",
-                                   duration: a_value > duration_higher_than,
-                                   request: an_instance_of(Hash),
-                                   rpc: rpc,
-                                   backtrace: an_instance_of(Array))
+        .to match a_hash_including(
+          start: a_value > 0,
+          feature: "#{service}##{rpc}",
+          duration: a_value > duration_higher_than,
+          request: an_instance_of(Hash),
+          rpc: rpc,
+          backtrace: an_instance_of(Array)
+        )
     end
 
     context 'when the response is not an enumerator' do