Cache PerformanceBar.allowed_user_ids list locally and in Redis

Signed-off-by: Rémy Coutable <remy@rymai.me>

lib/gitlab/performance_bar.rb

@@ -3,7 +3,8 @@
 module Gitlab
   module PerformanceBar
     ALLOWED_USER_IDS_KEY = 'performance_bar_allowed_user_ids:v2'.freeze
-    EXPIRY_TIME = 5.minutes
+    EXPIRY_TIME_L1_CACHE = 1.minute
+    EXPIRY_TIME_L2_CACHE = 5.minutes
 
     def self.enabled?(user = nil)
       return true if Rails.env.development?
@@ -19,20 +20,31 @@ module Gitlab
 
     # rubocop: disable CodeReuse/ActiveRecord
     def self.allowed_user_ids
-      Rails.cache.fetch(ALLOWED_USER_IDS_KEY, expires_in: EXPIRY_TIME) do
-        group = Group.find_by_id(allowed_group_id)
+      l1_cache_backend.fetch(ALLOWED_USER_IDS_KEY, expires_in: EXPIRY_TIME_L1_CACHE) do
+        l2_cache_backend.fetch(ALLOWED_USER_IDS_KEY, expires_in: EXPIRY_TIME_L2_CACHE) do
+          group = Group.find_by_id(allowed_group_id)
 
-        if group
-          GroupMembersFinder.new(group).execute.pluck(:user_id)
-        else
-          []
+          if group
+            GroupMembersFinder.new(group).execute.pluck(:user_id)
+          else
+            []
+          end
         end
       end
     end
     # rubocop: enable CodeReuse/ActiveRecord
 
     def self.expire_allowed_user_ids_cache
-      Rails.cache.delete(ALLOWED_USER_IDS_KEY)
+      l1_cache_backend.delete(ALLOWED_USER_IDS_KEY)
+      l2_cache_backend.delete(ALLOWED_USER_IDS_KEY)
+    end
+
+    def self.l1_cache_backend
+      Gitlab::ThreadMemoryCache.cache_backend
+    end
+
+    def self.l2_cache_backend
+      Rails.cache
     end
   end
 end

spec/lib/gitlab/performance_bar_spec.rb

@@ -3,17 +3,42 @@ require 'spec_helper'
 describe Gitlab::PerformanceBar do
   shared_examples 'allowed user IDs are cached' do
     before do
-      # Warm the Redis cache
+      # Warm the caches
       described_class.enabled?(user)
     end
 
     it 'caches the allowed user IDs in cache', :use_clean_rails_memory_store_caching do
       expect do
+        expect(described_class.l1_cache_backend).to receive(:fetch).and_call_original
+        expect(described_class.l2_cache_backend).not_to receive(:fetch)
         expect(described_class.enabled?(user)).to be_truthy
       end.not_to exceed_query_limit(0)
     end
+
+    it 'caches the allowed user IDs in L1 cache for 1 minute', :use_clean_rails_memory_store_caching do
+      Timecop.travel 2.minutes do
+        expect do
+          expect(described_class.l1_cache_backend).to receive(:fetch).and_call_original
+          expect(described_class.l2_cache_backend).to receive(:fetch).and_call_original
+          expect(described_class.enabled?(user)).to be_truthy
+        end.not_to exceed_query_limit(0)
+      end
+    end
+
+    it 'caches the allowed user IDs in L2 cache for 5 minutes', :use_clean_rails_memory_store_caching do
+      Timecop.travel 6.minutes do
+        expect do
+          expect(described_class.l1_cache_backend).to receive(:fetch).and_call_original
+          expect(described_class.l2_cache_backend).to receive(:fetch).and_call_original
+          expect(described_class.enabled?(user)).to be_truthy
+        end.not_to exceed_query_limit(2)
+      end
+    end
   end
 
+  it { expect(described_class.l1_cache_backend).to eq(Gitlab::ThreadMemoryCache.cache_backend) }
+  it { expect(described_class.l2_cache_backend).to eq(Rails.cache) }
+
   describe '.enabled?' do
     let(:user) { create(:user) }