batch enumerator optimization

no need to fetch next batch if the previous one is smaller than specified batch size
RailsEventStore · Dec 6, 2023 · 0ae6f8d · 0ae6f8d
1 parent 3315021
commit 0ae6f8d
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Showing 3 changed files with 8 additions and 9 deletions.
diff --git a/ruby_event_store-active_record/lib/ruby_event_store/active_record/batch_enumerator.rb b/ruby_event_store-active_record/lib/ruby_event_store/active_record/batch_enumerator.rb
@@ -17,8 +17,8 @@ def each
           batch_limit = [batch_size, total_limit - batch_offset].min
           results, offset_id = reader.call(offset_id, batch_limit)
 
-          break if results.empty?
-          yield results
+          yield results if results.any?
+          break if results.size < batch_size
         end
       end
 

diff --git a/ruby_event_store-active_record/spec/event_repository_spec.rb b/ruby_event_store-active_record/spec/event_repository_spec.rb
@@ -204,15 +204,14 @@ module ActiveRecord
           Stream.new("Dummy"),
           ExpectedVersion.any
         )
+        ::ActiveRecord::Base.logger = Logger.new(STDOUT)
 
         expect {
           repository.read(specification.in_batches.as_at.result).to_a
-        }.to match_query /SELECT.*FROM.*event_store_events.*ORDER BY .*event_store_events.*created_at.* ASC,.*event_store_events.*id.* ASC LIMIT.*.OFFSET.*/,
-                    2
+        }.to match_query /SELECT.*FROM.*event_store_events.*ORDER BY .*event_store_events.*created_at.* ASC,.*event_store_events.*id.* ASC LIMIT.*.OFFSET.*/
         expect {
           repository.read(specification.in_batches.as_of.result).to_a
-        }.to match_query /SELECT.*FROM.*event_store_events.*ORDER BY .*COALESCE(.*event_store_events.*valid_at.*, .*event_store_events.*created_at.*).* ASC,.*event_store_events.*id.* ASC LIMIT.*.OFFSET.*/,
-                    2
+        }.to match_query /SELECT.*FROM.*event_store_events.*ORDER BY .*COALESCE(.*event_store_events.*valid_at.*, .*event_store_events.*created_at.*).* ASC,.*event_store_events.*id.* ASC LIMIT.*.OFFSET.*/
       end
 
       specify "with batches and non-bi-temporal queries use monotonic ids" do
@@ -239,7 +238,7 @@ module ActiveRecord
         )
 
         expect {
-          repository.read(specification.in_batches.result).to_a
+          repository.read(specification.in_batches(3).result).to_a
         }.to match_query /SELECT.*FROM.*event_store_events.*WHERE.*event_store_events.id >*.*ORDER BY .*event_store_events.*id.* ASC LIMIT.*/
       end
 

diff --git a/ruby_event_store/lib/ruby_event_store/batch_enumerator.rb b/ruby_event_store/lib/ruby_event_store/batch_enumerator.rb
@@ -15,8 +15,8 @@ def each
         batch_limit = [batch_size, total_limit - batch_offset].min
         result = reader.call(batch_offset, batch_limit)
 
-        break if result.empty?
-        yield result
+        yield result if result.any?
+        break if result.size < batch_size
       end
     end