+# used for v2 (maybe)
+sub checkpoint {
+ my ($self) = @_;
+ return unless $self->{pid};
+ print { $self->{out} } "checkpoint\n" or wfail;
+ undef;
+}
+
+# used for v2
+sub get_mark {
+ my ($self, $mark) = @_;
+ die "not active\n" unless $self->{pid};
+ my ($r, $w) = $self->gfi_start;
+ print $w "get-mark $mark\n" or wfail;
+ defined(my $oid = <$r>) or die "get-mark failed, need git 2.6.0+\n";
+ $oid;
+}
+