meta,fstree: improve error message

Allow finding exact problematic IDs when iterating FSTree/resyncing Metabase.
Refs #3436.

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

Author: carpawell

pkg/local_object_storage/blobstor/fstree/fstree.go

@@ -247,6 +247,9 @@ func (t *FSTree) iterate(depth uint64, curPath []string,
 				}
 
 				err = objHandler(*addr, data)
+				if err != nil {
+					err = fmt.Errorf("handling %s object: %w", addr, err)
+				}
 			}
 		}
 

pkg/local_object_storage/shard/control.go

@@ -216,7 +216,7 @@ func (s *Shard) resyncObjectHandler(addr oid.Address, data []byte) error {
 
 		_, _, err = s.metaBase.Inhume(tombAddr, exp, false, tombMembers...)
 		if err != nil {
-			return fmt.Errorf("could not inhume objects: %w", err)
+			return fmt.Errorf("could not inhume [%s] objects: %w", oidsToString(memberIDs), err)
 		}
 	case objectSDK.TypeLock:
 		var lock objectSDK.Lock
@@ -229,7 +229,7 @@ func (s *Shard) resyncObjectHandler(addr oid.Address, data []byte) error {
 
 		err := s.metaBase.Lock(obj.GetContainerID(), obj.GetID(), locked)
 		if err != nil {
-			return fmt.Errorf("could not lock objects: %w", err)
+			return fmt.Errorf("could not lock [%s] objects: %w", oidsToString(locked), err)
 		}
 	}
 
@@ -241,6 +241,18 @@ func (s *Shard) resyncObjectHandler(addr oid.Address, data []byte) error {
 	return nil
 }
 
+func oidsToString(ids []oid.ID) string {
+	var res string
+	for i, id := range ids {
+		res += id.String()
+		if i != len(ids)-1 {
+			res += ", "
+		}
+	}
+
+	return res
+}
+
 // Close releases all Shard's components.
 func (s *Shard) Close() error {
 	components := []interface{ Close() error }{}