Improve performance bar permission checks

Checks the cookie first because it is a cheaper check. This also renames
enabled_for_user? to allowed_for_user? since that is more accurate.

app/controllers/concerns/with_performance_bar.rb

@@ -20,12 +20,12 @@ module WithPerformanceBar
   end
 
   def cookie_or_default_value
-    return false unless Gitlab::PerformanceBar.enabled_for_user?(current_user)
+    cookie_enabled = if cookies[:perf_bar_enabled].present?
+                       cookies[:perf_bar_enabled] == 'true'
+                     else
+                       cookies[:perf_bar_enabled] = 'true' if Rails.env.development?
+                     end
 
-    if cookies[:perf_bar_enabled].present?
-      cookies[:perf_bar_enabled] == 'true'
-    else
-      cookies[:perf_bar_enabled] = 'true' if Rails.env.development?
-    end
+    cookie_enabled && Gitlab::PerformanceBar.allowed_for_user?(current_user)
   end
 end

lib/api/helpers/performance_bar_helpers.rb

@@ -4,17 +4,17 @@ module API
   module Helpers
     module PerformanceBarHelpers
       def set_peek_enabled_for_current_request
-        Gitlab::SafeRequestStore.fetch(:peek_enabled) { perf_bar_cookie_enabled? && perf_bar_enabled_for_user? }
+        Gitlab::SafeRequestStore.fetch(:peek_enabled) { perf_bar_cookie_enabled? && perf_bar_allowed_for_user? }
       end
 
       def perf_bar_cookie_enabled?
         cookies[:perf_bar_enabled] == 'true'
       end
 
-      def perf_bar_enabled_for_user?
+      def perf_bar_allowed_for_user?
         # We cannot use `current_user` here because that method raises an exception when the user
         # is unauthorized and some API endpoints require that `current_user` is not called.
-        Gitlab::PerformanceBar.enabled_for_user?(find_user_from_sources)
+        Gitlab::PerformanceBar.allowed_for_user?(find_user_from_sources)
       end
     end
   end

lib/gitlab/performance_bar.rb

@@ -10,7 +10,7 @@ module Gitlab
       Gitlab::SafeRequestStore[:peek_enabled]
     end
 
-    def self.enabled_for_user?(user = nil)
+    def self.allowed_for_user?(user = nil)
       return true if Rails.env.development?
       return true if user&.admin?
       return false unless user && allowed_group_id

spec/lib/gitlab/performance_bar_spec.rb

@@ -6,7 +6,7 @@ RSpec.describe Gitlab::PerformanceBar do
   it { expect(described_class.l1_cache_backend).to eq(Gitlab::ProcessMemoryCache.cache_backend) }
   it { expect(described_class.l2_cache_backend).to eq(Rails.cache) }
 
-  describe '.enabled_for_user?' do
+  describe '.allowed_for_user?' do
     let(:user) { create(:user) }
 
     before do
@@ -14,24 +14,24 @@ RSpec.describe Gitlab::PerformanceBar do
     end
 
     it 'returns false when given user is nil' do
-      expect(described_class.enabled_for_user?(nil)).to be_falsy
+      expect(described_class.allowed_for_user?(nil)).to be_falsy
     end
 
     it 'returns true when given user is an admin' do
       user = build_stubbed(:user, :admin)
 
-      expect(described_class.enabled_for_user?(user)).to be_truthy
+      expect(described_class.allowed_for_user?(user)).to be_truthy
     end
 
     it 'returns false when allowed_group_id is nil' do
       expect(described_class).to receive(:allowed_group_id).and_return(nil)
 
-      expect(described_class.enabled_for_user?(user)).to be_falsy
+      expect(described_class.allowed_for_user?(user)).to be_falsy
     end
 
     context 'when allowed group ID does not exist' do
       it 'returns false' do
-        expect(described_class.enabled_for_user?(user)).to be_falsy
+        expect(described_class.allowed_for_user?(user)).to be_falsy
       end
     end
 
@@ -44,15 +44,15 @@ RSpec.describe Gitlab::PerformanceBar do
 
       context 'when user is not a member of the allowed group' do
         it 'returns false' do
-          expect(described_class.enabled_for_user?(user)).to be_falsy
+          expect(described_class.allowed_for_user?(user)).to be_falsy
         end
 
         context 'caching of allowed user IDs' do
-          subject { described_class.enabled_for_user?(user) }
+          subject { described_class.allowed_for_user?(user) }
 
           before do
             # Warm the caches
-            described_class.enabled_for_user?(user)
+            described_class.allowed_for_user?(user)
           end
 
           it_behaves_like 'allowed user IDs are cached'
@@ -65,15 +65,15 @@ RSpec.describe Gitlab::PerformanceBar do
         end
 
         it 'returns true' do
-          expect(described_class.enabled_for_user?(user)).to be_truthy
+          expect(described_class.allowed_for_user?(user)).to be_truthy
         end
 
         context 'caching of allowed user IDs' do
-          subject { described_class.enabled_for_user?(user) }
+          subject { described_class.allowed_for_user?(user) }
 
           before do
             # Warm the caches
-            described_class.enabled_for_user?(user)
+            described_class.allowed_for_user?(user)
           end
 
           it_behaves_like 'allowed user IDs are cached'
@@ -91,7 +91,7 @@ RSpec.describe Gitlab::PerformanceBar do
       end
 
       it 'returns the nested group' do
-        expect(described_class.enabled_for_user?(user)).to be_truthy
+        expect(described_class.allowed_for_user?(user)).to be_truthy
       end
     end
 
@@ -101,7 +101,7 @@ RSpec.describe Gitlab::PerformanceBar do
       end
 
       it 'returns false' do
-        expect(described_class.enabled_for_user?(user)).to be_falsy
+        expect(described_class.allowed_for_user?(user)).to be_falsy
       end
     end
   end