reword `targets` to `metric tags`

add changelog

app/workers/update_merge_requests_worker.rb

@@ -2,10 +2,10 @@ class UpdateMergeRequestsWorker
   include Sidekiq::Worker
   include DedicatedSidekiqQueue
 
-  attr_reader :targets # for metrics tags
+  attr_reader :metrics_tags
 
   def initialize
-    @targets = {}
+    @metrics_tags = {}
   end
 
   def perform(project_id, user_id, oldrev, newrev, ref)
@@ -15,10 +15,11 @@ class UpdateMergeRequestsWorker
     user = User.find_by(id: user_id)
     return unless user
 
-    @targets = {
+    @metrics_tags = {
       project_id: project_id,
       user_id: user_id
     }
+
     MergeRequests::RefreshService.new(project, user).execute(oldrev, newrev, ref)
   end
 end

changelogs/unreleased/35914-merge-request-update-worker-is-slow.yml

+---
+title: Add metric tagging for sidekiq workers
+merge_request: 15111
+author:
+type: added

lib/gitlab/metrics/sidekiq_middleware.rb

@@ -12,7 +12,7 @@ module Gitlab
           trans.set(:sidekiq_queue_duration, Time.now.to_f - (message['enqueued_at'] || message['created_at'] || 0))
           trans.run { yield }
 
-          worker.targets.each { |name, target| trans.add_tag(name, target) } if worker.respond_to?(:targets)
+          worker.metrics_tags.each { |tag, value| trans.add_tag(tag, value) } if worker.respond_to?(:metrics_tags)
         rescue Exception => error # rubocop: disable Lint/RescueException
           trans.add_event(:sidekiq_exception)
 

spec/lib/gitlab/metrics/sidekiq_middleware_spec.rb

@@ -47,11 +47,11 @@ describe Gitlab::Metrics::SidekiqMiddleware do
     end
 
     it 'tags the metrics accordingly' do
-      targets = { one: 1, two: 2 }
+      tags = { one: 1, two: 2 }
       worker = double(:worker, class: double(:class, name: 'TestWorker'))
-      allow(worker).to receive(:targets).and_return(targets)
+      allow(worker).to receive(:metrics_tags).and_return(tags)
 
-      targets.each do |tag, value|
+      tags.each do |tag, value|
         expect_any_instance_of(Gitlab::Metrics::Transaction).to receive(:add_tag)
           .with(tag, value)
       end