Class TcpMetrics

netty/src/main/java/io/grpc/netty/TcpMetrics.java:38–227

Utility for collecting TCP metrics from Netty channels.

 * Utility for collecting TCP metrics from Netty channels.
 */
final class TcpMetrics {
  private static final Logger log = Logger.getLogger(TcpMetrics.class.getName());

  static EpollInfo epollInfo = loadEpollInfo();

  static final class EpollInfo {
    final Class<?> channelClass;
    final java.lang.reflect.Constructor<?> infoConstructor;
    final Method tcpInfo;
    final Method totalRetrans;
    final Method retransmits;
    final Method rtt;

    EpollInfo(
        Class<?> channelClass,
        java.lang.reflect.Constructor<?> infoConstructor,
        Method tcpInfo,
        Method totalRetrans,
        Method retransmits,
        Method rtt) {
      this.channelClass = channelClass;
      this.infoConstructor = infoConstructor;
      this.tcpInfo = tcpInfo;
      this.totalRetrans = totalRetrans;
      this.retransmits = retransmits;
      this.rtt = rtt;
    }
  }

  static EpollInfo loadEpollInfo() {
    boolean epollAvailable = false;
    try {
      Class<?> epollClass = Class.forName("io.netty.channel.epoll.Epoll");
      Method isAvailableMethod = epollClass.getDeclaredMethod("isAvailable");
      epollAvailable = (Boolean) isAvailableMethod.invoke(null);
      if (epollAvailable) {
        Class<?> channelClass = Class.forName("io.netty.channel.epoll.EpollSocketChannel");
        Class<?> infoClass = Class.forName("io.netty.channel.epoll.EpollTcpInfo");
        return new EpollInfo(
            channelClass,
            infoClass.getDeclaredConstructor(),
            channelClass.getMethod("tcpInfo", infoClass),
            infoClass.getMethod("totalRetrans"),
            infoClass.getMethod("retrans"),
            infoClass.getMethod("rtt"));
      }
    } catch (ReflectiveOperationException e) {
      log.log(Level.FINE, "Failed to initialize Epoll tcp_info reflection", e);
    } finally {
      log.log(Level.INFO, "Epoll available during static init of TcpMetrics:"
          + "{0}", epollAvailable);
    }
    return null;
  }

  private static final long RECORD_INTERVAL_MILLIS = TimeUnit.MINUTES.toMillis(5);
  private final MetricRecorder metricRecorder;
  private final Object tcpInfo;