Use `replicables_for_geo_node` as SSOT

...to answer the question: "Which records should be synced?".

ee/app/models/concerns/geo/blob_replicator_strategy.rb

@@ -21,7 +21,7 @@ module Geo
 
     # Called by Gitlab::Geo::Replicator#consume
     def consume_event_created(**params)
-      return if excluded_by_selective_sync?
+      return unless in_replicables_for_geo_node?
 
       download
     end
@@ -34,7 +34,7 @@ module Geo
 
     # Called by Gitlab::Geo::Replicator#consume
     def consume_event_deleted(**params)
-      return if excluded_by_selective_sync?
+      return unless in_replicables_for_geo_node?
 
       replicate_destroy(params)
     end

ee/lib/gitlab/geo/replicable_model.rb

@@ -82,6 +82,10 @@ module Gitlab
           replicator.carrierwave_uploader.exists?
         end
       end
+
+      def in_replicables_for_geo_node?
+        self.class.replicables_for_geo_node.id_in(self).exists?
+      end
     end
   end
 end

ee/lib/gitlab/geo/replicator.rb

@@ -19,6 +19,7 @@ module Gitlab
       attr_reader :model_record_id
 
       delegate :model, to: :class
+      delegate :in_replicables_for_geo_node?, to: :model_record
 
       class << self
         delegate :find_unsynced_registries, :find_failed_registries, to: :registry_class
@@ -275,26 +276,6 @@ module Gitlab
         registry.verification_checksum
       end
 
-      # This method does not yet cover resources that are owned by a namespace
-      # but not a project, because we do not have that use-case...yet.
-      # E.g. GroupWikis will need it.
-      def excluded_by_selective_sync?
-        # If the replicable is not owned by a project or namespace, then selective sync cannot apply to it.
-        return false unless parent_project_id
-
-        !current_node.projects_include?(parent_project_id)
-      end
-
-      def parent_project_id
-        strong_memoize(:parent_project_id) do
-          # We should never see this at runtime. All Replicators should be tested
-          # by `it_behaves_like 'a replicator'`, which would reveal this problem.
-          selective_sync_not_implemented_error(__method__) unless model_record.respond_to?(:project_id)
-
-          model_record.project_id
-        end
-      end
-
       # Return exactly the data needed by `for_replicable_params` to
       # reinstantiate this Replicator elsewhere.
       #
@@ -335,11 +316,6 @@ module Gitlab
       def current_node
         Gitlab::Geo.current_node
       end
-
-      def selective_sync_not_implemented_error(method_name)
-        raise NotImplementedError,
-            "#{self.class} does not implement #{method_name}. If selective sync is not applicable, just return nil."
-      end
     end
   end
 end

ee/spec/lib/gitlab/geo/replicator_spec.rb

@@ -179,68 +179,6 @@ RSpec.describe Gitlab::Geo::Replicator do
       end
     end
 
-    describe '#excluded_by_selective_sync?' do
-      subject(:replicator) { Geo::DummyReplicator.new }
-
-      before do
-        stub_current_geo_node(secondary_node)
-      end
-
-      context 'when parent_project_id is not nil' do
-        before do
-          allow(replicator).to receive(:parent_project_id).and_return(123456)
-        end
-
-        context 'when the current Geo node excludes the parent_project due to selective sync' do
-          it 'returns true' do
-            expect(secondary_node).to receive(:projects_include?).with(123456).and_return(false)
-
-            expect(replicator.excluded_by_selective_sync?).to eq(true)
-          end
-        end
-
-        context 'when the current Geo node does not exclude the parent_project due to selective sync' do
-          it 'returns false' do
-            expect(secondary_node).to receive(:projects_include?).with(123456).and_return(true)
-
-            expect(replicator.excluded_by_selective_sync?).to eq(false)
-          end
-        end
-      end
-
-      context 'when parent_project_id is nil' do
-        before do
-          expect(replicator).to receive(:parent_project_id).and_return(nil)
-        end
-
-        it 'returns false' do
-          expect(replicator.excluded_by_selective_sync?).to eq(false)
-        end
-      end
-    end
-
-    describe '#parent_project_id' do
-      subject(:replicator) { Geo::DummyReplicator.new(model_record: model_record) }
-
-      # We cannot infer parent project, so parent_project_id should be overridden.
-      context 'when model_record does not respond to project_id' do
-        let(:model_record) { double(:model_record, id: 555) }
-
-        it 'raises NotImplementedError' do
-          expect { replicator.parent_project_id }.to raise_error(NotImplementedError)
-        end
-      end
-
-      # We assume project_id to be the parent project.
-      context 'when model_record responds to project_id' do
-        let(:model_record) { double(:model_record, id: 555, project_id: 1234) }
-
-        it 'does not error' do
-          expect(replicator.parent_project_id).to eq(1234)
-        end
-      end
-    end
-
     describe '.for_replicable_params' do
       it 'returns the corresponding Replicator instance' do
         replicator = described_class.for_replicable_params(replicable_name: 'dummy', replicable_id: 123456)
@@ -295,5 +233,9 @@ RSpec.describe Gitlab::Geo::Replicator do
         end
       end
     end
+
+    describe '#in_replicables_for_geo_node?' do
+      it { is_expected.to delegate_method(:in_replicables_for_geo_node?).to(:model_record) }
+    end
   end
 end

ee/spec/support/shared_examples/models/concerns/blob_replicator_strategy_shared_examples.rb

@@ -104,9 +104,9 @@ RSpec.shared_examples 'a blob replicator' do
   end
 
   describe '#consume_event_created' do
-    context "when the blob's project is not excluded by selective sync" do
+    context "when the blob's project is in replicables for this geo node" do
       it 'invokes Geo::BlobDownloadService' do
-        expect(replicator).to receive(:excluded_by_selective_sync?).and_return(false)
+        expect(replicator).to receive(:in_replicables_for_geo_node?).and_return(true)
         service = double(:service)
 
         expect(service).to receive(:execute)
@@ -116,9 +116,9 @@ RSpec.shared_examples 'a blob replicator' do
       end
     end
 
-    context "when the blob's project is excluded by selective sync" do
+    context "when the blob's project is not in replicables for this geo node" do
       it 'does not invoke Geo::BlobDownloadService' do
-        expect(replicator).to receive(:excluded_by_selective_sync?).and_return(true)
+        expect(replicator).to receive(:in_replicables_for_geo_node?).and_return(false)
 
         expect(::Geo::BlobDownloadService).not_to receive(:new)
 
@@ -128,9 +128,9 @@ RSpec.shared_examples 'a blob replicator' do
   end
 
   describe '#consume_event_deleted' do
-    context "when the blob's project is not excluded by selective sync" do
+    context "when the blob's project is in replicables for this geo node" do
       it 'invokes Geo::FileRegistryRemovalService' do
-        expect(replicator).to receive(:excluded_by_selective_sync?).and_return(false)
+        expect(replicator).to receive(:in_replicables_for_geo_node?).and_return(true)
         service = double(:service)
 
         expect(service).to receive(:execute)
@@ -141,9 +141,9 @@ RSpec.shared_examples 'a blob replicator' do
       end
     end
 
-    context "when the blob's project is excluded by selective sync" do
+    context "when the blob's project is not in replicables for this geo node" do
       it 'does not invoke Geo::FileRegistryRemovalService' do
-        expect(replicator).to receive(:excluded_by_selective_sync?).and_return(true)
+        expect(replicator).to receive(:in_replicables_for_geo_node?).and_return(false)
 
         expect(::Geo::FileRegistryRemovalService).not_to receive(:new)
 

ee/spec/support/shared_examples/models/concerns/replicator_shared_examples.rb

@@ -13,12 +13,6 @@
 RSpec.shared_examples 'a replicator' do
   include EE::GeoHelpers
 
-  describe '#parent_project_id' do
-    it 'is implemented if needed' do
-      expect { replicator.parent_project_id }.not_to raise_error
-    end
-  end
-
   context 'Geo node status' do
     context 'on a secondary node' do
       let_it_be(:registry_factory) { registry_factory_name(described_class.registry_class) }