fix: speed on ReadN (#279)

* allocate memory on tests

* similar behavior as before

* fix performance

* fix lint

* remove comments

Author: raulb

source/logrepl/cdc.go

@@ -124,7 +124,7 @@ func (i *CDCIterator) NextN(ctx context.Context, n int) ([]opencdc.Record, error
 		return nil, fmt.Errorf("n must be greater than 0, got %d", n)
 	}
 
-	recs := make([]opencdc.Record, 0, n)
+	var recs []opencdc.Record
 
 	// Block until at least one record is received or context is canceled
 	select {

source/logrepl/cdc_test.go

@@ -510,7 +510,7 @@ func TestCDCIterator_NextN(t *testing.T) {
 		}
 
 		// Will keep calling NextN until all records are received
-		var records []opencdc.Record
+		records := make([]opencdc.Record, 0, 2)
 		for len(records) < 2 {
 			recordsTmp, err := i.NextN(ctx, 5)
 			is.NoErr(err)

source/logrepl/combined.go

@@ -131,7 +131,7 @@ func (c *CombinedIterator) NextN(ctx context.Context, n int) ([]opencdc.Record,
 		}
 
 		sdk.Logger(ctx).Debug().Msg("Snapshot completed, switching to CDC mode")
-		return c.activeIterator.NextN(ctx, n)
+		return c.NextN(ctx, n)
 	}
 	return records, nil
 }

source/logrepl/combined_test.go

@@ -289,7 +289,7 @@ func TestCombinedIterator_NextN(t *testing.T) {
 		is.NoErr(err)
 
 		// Request 2 records in CDC mode
-		var records []opencdc.Record
+		records := make([]opencdc.Record, 0, 2)
 		var retries int
 		maxRetries := 10
 		for retries < maxRetries {