+# faster than ->count due to how SQLite works
+sub has_entries {
+ my ($self) = @_;
+ my @n = $self->{dbh}->selectrow_array('SELECT k FROM kv LIMIT 1');
+ scalar(@n) ? 1 : undef;
+}
+
+sub dbh_release {
+ my ($self, $lock) = @_;
+ my $dbh = delete $self->{dbh} or return;
+ $lock //= $self->lock_for_scope_fast; # may be needed for WAL
+ %{$dbh->{CachedKids}} = (); # cleanup prepare_cached
+ $dbh->disconnect;
+}
+
+sub DESTROY {
+ my ($self) = @_;
+ dbh_release($self);
+ my $dir = delete $self->{"tmp$$.$self"} or return;
+ my $tries = 0;
+ do {
+ $! = 0;
+ eval { rmtree($dir) };
+ } while ($@ && $!{ENOENT} && $tries++ < 5);
+ warn "error removing $dir: $@" if $@;
+ warn "Took $tries tries to remove $dir\n" if $tries;
+}
+