Fix last processed event id when no event_log_state exist

lib/gitlab/geo/log_cursor/events.rb

@@ -28,10 +28,16 @@ module Gitlab
 
         # @return [Integer] id of last replicated event
         def self.last_processed
-          last = ::Geo::EventLogState.last_processed.try(:id)
+          last = ::Geo::EventLogState.last_processed&.id
           return last if last
 
-          ::Geo::EventLog.any? ? ::Geo::EventLog.last.id : -1
+          if ::Geo::EventLog.any?
+            event_id = ::Geo::EventLog.last.id
+            save_processed(event_id)
+            event_id
+          else
+            -1
+          end
         end
 
         # private methods

spec/lib/gitlab/geo/log_cursor/events_spec.rb

@@ -2,20 +2,27 @@ require 'spec_helper'
 
 describe Gitlab::Geo::LogCursor::Events, lib: true do
   describe '.fetch_in_batches' do
-    let!(:event_log) { create(:geo_event_log) }
+    let!(:event_log_1) { create(:geo_event_log) }
+    let!(:event_log_2) { create(:geo_event_log) }
 
-    before do
-      allow(described_class).to receive(:last_processed) { -1 }
+    context 'when no event_log_state exist' do
+      it 'does not yield a group of events' do
+        expect { |b| described_class.fetch_in_batches(&b) }.not_to yield_with_args([event_log_1, event_log_2])
+      end
     end
 
-    it 'yields a group of events' do
-      expect { |b| described_class.fetch_in_batches(&b) }.to yield_with_args([event_log])
-    end
+    context 'when there is already an event_log_state' do
+      let!(:event_log_state) { create(:geo_event_log_state, event_id: event_log_1.id - 1) }
+
+      it 'yields a group of events' do
+        expect { |b| described_class.fetch_in_batches(&b) }.to yield_with_args([event_log_1, event_log_2])
+      end
 
-    it 'saves processed files after yielding' do
-      expect(described_class).to receive(:save_processed)
+      it 'saves last event as last processed after yielding' do
+        described_class.fetch_in_batches { |batch| batch }
 
-      described_class.fetch_in_batches { |batch| batch }
+        expect(Geo::EventLogState.last.event_id).to eq(event_log_2.id)
+      end
     end
 
     it 'skips execution if cannot achieve a lease' do
@@ -26,15 +33,15 @@ describe Gitlab::Geo::LogCursor::Events, lib: true do
   end
 
   describe '.save_processed' do
-    it 'saves a new entry in geo_event_log_state' do
+    it 'creates a new event_log_state when no event_log_state exist' do
       expect { described_class.save_processed(1) }.to change(Geo::EventLogState, :count).by(1)
       expect(Geo::EventLogState.last.event_id).to eq(1)
     end
 
-    it 'removes older entries from geo_event_log_state' do
+    it 'updates the event_id when there is already an event_log_state' do
       create(:geo_event_log_state)
 
-      expect { described_class.save_processed(2) }.to change(Geo::EventLogState, :count).by(0)
+      expect { described_class.save_processed(2) }.not_to change(Geo::EventLogState, :count)
       expect(Geo::EventLogState.last.event_id).to eq(2)
     end
   end
@@ -52,6 +59,11 @@ describe Gitlab::Geo::LogCursor::Events, lib: true do
       it 'returns last event id' do
         expect(described_class.last_processed).to eq(event_log.id)
       end
+
+      it 'saves last event as the last processed' do
+        expect { described_class.last_processed }.to change(Geo::EventLogState, :count).by(1)
+        expect(Geo::EventLogState.last.event_id).to eq(event_log.id)
+      end
     end
 
     context 'when there is already an event_log_state' do