static function perform($from, $to)
{
$from = gb::version_parse($from);
$to = gb::version_parse($to);
$froms = gb::version_format($from);
$tos = gb::version_format($to);
if ($from === $to) {
return null;
}
$is_upgrade = $from < $to;
$stages = self::build_stages($from, $to);
gb::log('%s gitblog %s -> %s in %d stages', $is_upgrade ? 'upgrading' : 'downgrading', $froms, $tos, count($stages));
# don't break on client abort
ignore_user_abort(true);
foreach ($stages as $v => $stagefunc) {
$prevvs = gb::version_format($v > 0 ? $v - 1 : $v);
gb::log('%s -> %s (%s)', $prevvs, gb::version_format($v), $stagefunc[1], $v);
# write prev version to site.json so next run will take off where we crashed, if we crash.
$orig_v = gb::$version;
gb::$version = $prevvs;
gb_maint::sync_site_state();
gb::$version = $orig_v;
$stages[$v] = call_user_func($stagefunc, $from, $to);
}
gb_maint::sync_site_state();
return $stages;
}