* ... * * Levels: a ratio 0..1 for cpu_usage and physical_utilisation, bytes per second for network_usage / disk_usage, KiB for * memory_free_kib (an alarm when it goes BELOW: alarm_trigger_sense low), MiB per second for sr_io_throughput_total_per_host. * When the value stays over the level for the trigger period, perfmon writes a message ALARM (body "value: …\nconfig: …"), * then keeps quiet for the inhibit period. */ final class Perfmon { /** what XenCenter offers for each kind of object */ public const VARIABLES = [ 'vm' => ['cpu_usage', 'network_usage', 'disk_usage'], 'host' => ['cpu_usage', 'memory_free_kib', 'network_usage'], 'sr' => ['physical_utilisation', 'sr_io_throughput_total_per_host'], ]; /** @return array variable name => its alarm */ public static function parse(string $xml): array { $out = []; preg_match_all('#(.*?)#s', $xml, $variables); foreach ($variables[1] as $variable) { $value = fn (string $tag): ?string => preg_match('#<' . $tag . '\s+value="([^"]*)"#', $variable, $m) ? html_entity_decode($m[1], ENT_XML1) : null; $name = $value('name'); $level = $value('alarm_trigger_level'); if ($name === null || $name === '' || $level === null) { continue; } $out[$name] = ['level' => (float)$level, 'period' => (int)($value('alarm_trigger_period') ?? 60), 'inhibit' => (int)($value('alarm_auto_inhibit_period') ?? 3600)]; } return $out; } /** @param array $alarms */ public static function build(array $alarms): string { $xml = ''; foreach ($alarms as $name => $a) { $xml .= self::variable($name, $a, ''); } return $xml . ''; } /** One , $indent between the lines (perfmon's message bodies are indented with tabs, one tag per line). @param array{level: float, period: int, inhibit: int} $a */ public static function variable(string $name, array $a, string $indent = "\n\t"): string { $end = $indent === '' ? '' : "\n"; return '' . $indent . '' . $indent . '' . $indent . '' . $indent . '' . ($name === 'memory_free_kib' ? $indent . '' : '') . $end . ''; } /** The body of the ALARM message perfmon writes. @param array{level: float, period: int, inhibit: int} $a */ public static function alarmBody(string $name, float $value, array $a): string { return 'value: ' . sprintf('%.6F', $value) . "\nconfig:\n" . self::variable($name, $a) . "\n"; } /** Below the level is the alarm for free memory, above it for the rest. */ public static function fires(string $name, float $value, float $level): bool { return $name === 'memory_free_kib' ? $value < $level : $value > $level; } private static function number(float $x): string { $s = rtrim(rtrim(sprintf('%.6F', $x), '0'), '.'); return $s === '' || $s === '-0' ? '0' : $s; } }