Group performance bar SQL queries

Instead of logging each query separately, queries are grouped
by its location (formed by filename and method name). The main
reason is that in Kibana it's not easy to group results by multiple
fields (the only option is using script field)

doc/administration/logs.md

@@ -1006,7 +1006,7 @@ installations from source.
 Performance bar statistics (currently only duration of SQL queries) are recorded in that file. For example:
 
 ```json
-{"severity":"INFO","time":"2020-12-04T09:29:44.592Z","correlation_id":"33680b1490ccd35981b03639c406a697","filename":"app/models/ci/pipeline.rb","filenum":"395","method":"each_with_object","request_id":"rYHomD0VJS4","duration_ms":26.889,"type": "sql"}
+{"severity":"INFO","time":"2020-12-04T09:29:44.592Z","correlation_id":"33680b1490ccd35981b03639c406a697","filename":"app/models/ci/pipeline.rb","method_path":"app/models/ci/pipeline.rb:each_with_object","request_id":"rYHomD0VJS4","duration_ms":26.889,"count":2,"type": "sql"}
 ```
 
 These statistics are logged on .com only, disabled on self-deployments.

lib/gitlab/performance_bar/stats.rb

@@ -27,27 +27,40 @@ module Gitlab
       end
 
       def log_sql_queries(id, data)
-        return [] unless queries = data.dig('data', 'active-record', 'details')
-
-        queries.each do |query|
-          next unless location = parse_backtrace(query['backtrace'])
+        queries_by_location(data).each do |location, queries|
+          next unless location
 
-          log_info = location.merge(
+          duration = queries.sum { |query| query['duration'].to_f }
+          log_info = {
+            method_path: "#{location[:filename]}:#{location[:method]}",
+            filename: location[:filename],
             type: :sql,
             request_id: id,
-            duration_ms: query['duration'].to_f
-          )
+            count: queries.count,
+            duration_ms: duration
+          }
 
           logger.info(log_info)
         end
       end
 
+      def queries_by_location(data)
+        return [] unless queries = data.dig('data', 'active-record', 'details')
+
+        queries.group_by do |query|
+          parse_backtrace(query['backtrace'])
+        end
+      end
+
       def parse_backtrace(backtrace)
         return unless match = /(?<filename>.*):(?<filenum>\d+):in `(?<method>.*)'/.match(backtrace.first)
 
         {
           filename: match[:filename],
-          filenum: match[:filenum].to_i,
+          # filenum may change quite frequently with every change in the file,
+          # because the intention is to aggregate these queries, we group
+          # them rather by method name which should not change so frequently
+          # filenum: match[:filenum].to_i,
           method: match[:method]
         }
       end

spec/lib/gitlab/performance_bar/stats_spec.rb

@@ -22,10 +22,12 @@ RSpec.describe Gitlab::PerformanceBar::Stats do
 
         expect(logger).to receive(:info)
           .with({ duration_ms: 1.096, filename: 'lib/gitlab/pagination/offset_pagination.rb',
-                  filenum: 53, method: 'add_pagination_headers', request_id: 'foo', type: :sql })
+                  method_path: 'lib/gitlab/pagination/offset_pagination.rb:add_pagination_headers',
+                  count: 1, request_id: 'foo', type: :sql })
         expect(logger).to receive(:info)
-          .with({ duration_ms: 0.817, filename: 'lib/api/helpers.rb',
-                  filenum: 112, method: 'find_project', request_id: 'foo', type: :sql }).twice
+          .with({ duration_ms: 1.634, filename: 'lib/api/helpers.rb',
+                  method_path: 'lib/api/helpers.rb:find_project',
+                  count: 2, request_id: 'foo', type: :sql })
 
         subject
       end