[#182] Reuse search filter in policer

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/services/policer/queue.go

@@ -9,16 +9,15 @@ type jobQueue struct {
 	localStorage *localstore.Storage
 }
 
+var jobFilter object.SearchFilters
+
 func (q *jobQueue) Select(limit int) ([]*object.Address, error) {
 	// TODO: optimize the logic for selecting objects
 	// We can prioritize objects for migration, newly arrived objects, etc.
 	// It is recommended to make changes after updating the metabase
 
-	jobFilter := object.NewSearchFilters()
-	jobFilter.AddPhyFilter()
-
 	// FIXME: add the ability to limit Select result
-	res, err := q.localStorage.Select(jobFilter)
+	res, err := q.localStorage.Select(getJobFilter())
 	if err != nil {
 		return nil, err
 	}
@@ -29,3 +28,12 @@ func (q *jobQueue) Select(limit int) ([]*object.Address, error) {
 
 	return res[:limit], nil
 }
+
+// getJobFilter is a getter for a singleton instance.
+func getJobFilter() object.SearchFilters {
+	if len(jobFilter) == 0 {
+		jobFilter.AddPhyFilter() // this initiates a list of filters
+	}
+
+	return jobFilter
+}