[#142] metabase: Fix false-positive select

Fix a bug in the selection when an object could be added to the result after
a mismatch in the previous filter.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/local_object_storage/metabase/select.go

@@ -45,8 +45,8 @@ func (db *DB) Select(fs object.SearchFilters) ([]*object.Address, error) {
 			})
 		}
 
-		// keep processed addresses
-		mAddr := make(map[string]struct{})
+		// keep processed addresses (false if address was added and excluded later)
+		mAddr := make(map[string]bool)
 
 		for _, f := range fs {
 			matchFunc, ok := db.matchers[f.Operation()]
@@ -76,9 +76,11 @@ func (db *DB) Select(fs object.SearchFilters) ([]*object.Address, error) {
 
 				for i := range strs {
 					if include {
-						mAddr[strs[i]] = struct{}{}
+						if _, ok := mAddr[strs[i]]; !ok {
+							mAddr[strs[i]] = true
+						}
 					} else {
-						delete(mAddr, strs[i])
+						mAddr[strs[i]] = false
 					}
 				}
 
@@ -88,7 +90,11 @@ func (db *DB) Select(fs object.SearchFilters) ([]*object.Address, error) {
 			}
 		}
 
-		for a := range mAddr {
+		for a, inc := range mAddr {
+			if !inc {
+				continue
+			}
+
 			// check if object marked as deleted
 			if objectRemoved(tx, []byte(a)) {
 				return nil

pkg/local_object_storage/metabase/select_test.go

@@ -88,3 +88,26 @@ func BenchmarkDB_Select(b *testing.B) {
 		})
 	}
 }
+
+func TestMismatchAfterMatch(t *testing.T) {
+	db := newDB(t)
+	defer releaseDB(db)
+
+	obj := generateObject(t, testPrm{
+		attrNum: 1,
+	})
+
+	require.NoError(t, db.Put(obj))
+
+	a := obj.GetAttributes()[0]
+
+	fs := objectSDK.SearchFilters{}
+
+	// 1st - mismatching filter
+	fs.AddFilter(a.GetKey(), a.GetValue()+"1", objectSDK.MatchStringEqual)
+
+	// 2nd - matching filter
+	fs.AddFilter(a.GetKey(), a.GetValue(), objectSDK.MatchStringEqual)
+
+	testSelect(t, db, fs)
+}