fix: handle deleted segments gracefully instead of looping on 404

lib/splitclient-rb/cache/repositories/segments_repository.rb

@@ -39,6 +39,10 @@ def used_segment_names
           @adapter.get_set(namespace_key('.segments.registered'))
         end
 
+        def remove_registered_segment(name)
+          @adapter.delete_from_set(namespace_key('.segments.registered'), name)
+        end
+
         def set_change_number(name, last_change)
           @adapter.set_string(namespace_key(".segment.#{name}.till"), last_change)
         end

lib/splitclient-rb/engine/api/segments.rb

@@ -19,6 +19,12 @@ def fetch_segments_by_names(names, fetch_options = { cache_control_headers: fals
 
           loop do
             segment = fetch_segment_changes(name, since, fetch_options)
+
+            if segment.nil?
+              @segments_repository.remove_registered_segment(name)
+              break
+            end
+
             @segments_repository.add_to_segment(segment)
 
             @config.split_logger.log_if_debug("Segment #{name} fetched before: #{since}, \
@@ -64,6 +70,9 @@ def fetch_segment_changes(name, since, fetch_options = { cache_control_headers:
           @config.logger.error('Factory Instantiation: You passed a browser type api_key, ' \
             'please grab an api key from the Split console that is of type sdk')
           @config.valid_mode =  false
+        elsif response.status == 404
+          @config.logger.warn("Segment '#{name}' not found (404). The segment may have been removed from the Split environment.")
+          nil
         else
           @telemetry_runtime_producer.record_sync_error(Telemetry::Domain::Constants::SEGMENT_SYNC, response.status)
 

spec/engine/api/segments_spec.rb

@@ -88,14 +88,24 @@
       expect(log.string).to include ':added=>["max", "dan"]'
     end
 
-    it 'throws exception if request to fetch segments from API returns unexpected status code' do
+    it 'returns nil and logs warning when segment is not found (404)' do
       stub_request(:get, 'https://sdk.split.io/api/segmentChanges/employees?since=-1')
         .to_return(status: 404)
 
-      expect { segments_api.send(:fetch_segment_changes, 'employees', -1) }.to raise_error(
-        'Split SDK failed to connect to backend to fetch segments'
-      )
-      expect(log.string).to include 'Unexpected status code while fetching segments'
+      result = segments_api.send(:fetch_segment_changes, 'employees', -1)
+      expect(result).to be_nil
+      expect(log.string).to include "Segment 'employees' not found (404)"
+    end
+
+    it 'removes segment from registered set on 404 during fetch_segments_by_names' do
+      stub_request(:get, 'https://sdk.split.io/api/segmentChanges/employees?since=-1')
+        .to_return(status: 404)
+
+      segments_repository.instance_variable_get(:@adapter)
+        .add_to_set('SPLITIO.segments.registered', 'employees')
+
+      expect { segments_api.fetch_segments_by_names(['employees']) }.not_to raise_error
+      expect(segments_repository.used_segment_names).not_to include('employees')
     end
 
     it 'throws exception if request to get splits from API fails' do