/**
   * Checks if address can be reached using one argument InetAddress.isReachable() version or ping
   * command if failed.
   *
   * @param addr Address to check.
   * @param reachTimeout Timeout for the check.
   * @return {@code True} if address is reachable.
   */
  public static boolean reachableByPing(InetAddress addr, int reachTimeout) {
    try {
      if (addr.isReachable(reachTimeout)) return true;

      String cmd = String.format("ping -%s 1 %s", U.isWindows() ? "n" : "c", addr.getHostAddress());

      Process myProc = Runtime.getRuntime().exec(cmd);

      myProc.waitFor();

      return myProc.exitValue() == 0;
    } catch (IOException ignore) {
      return false;
    } catch (InterruptedException ignored) {
      Thread.currentThread().interrupt();

      return false;
    }
  }
  /** {@inheritDoc} */
  @SuppressWarnings("BusyWait")
  @Override
  public void start(GridRestProtocolHandler hnd) throws GridException {
    InetAddress locHost;

    try {
      locHost = U.resolveLocalHost(ctx.config().getLocalHost());
    } catch (IOException e) {
      throw new GridException(
          "Failed to resolve local host to bind address: " + ctx.config().getLocalHost(), e);
    }

    System.setProperty(GG_JETTY_HOST, locHost.getHostAddress());

    jettyHnd =
        new GridJettyRestHandler(
            hnd,
            new C1<String, Boolean>() {
              @Override
              public Boolean apply(String tok) {
                return F.isEmpty(secretKey) || authenticate(tok);
              }
            },
            log);

    String jettyPath = ctx.config().getRestJettyPath();

    final URL cfgUrl;

    if (jettyPath == null) {
      cfgUrl = null;

      if (log.isDebugEnabled())
        log.debug("Jetty configuration file is not provided, using defaults.");
    } else {
      cfgUrl = U.resolveGridGainUrl(jettyPath);

      if (cfgUrl == null)
        throw new GridSpiException("Invalid Jetty configuration file: " + jettyPath);
      else if (log.isDebugEnabled()) log.debug("Jetty configuration file: " + cfgUrl);
    }

    loadJettyConfiguration(cfgUrl);

    AbstractNetworkConnector connector = getJettyConnector();

    try {
      host = InetAddress.getByName(connector.getHost());
    } catch (UnknownHostException e) {
      throw new GridException("Failed to resolve Jetty host address: " + connector.getHost(), e);
    }

    int initPort = connector.getPort();

    int lastPort = initPort + ctx.config().getRestPortRange() - 1;

    for (port = initPort; port <= lastPort; port++) {
      connector.setPort(port);

      if (startJetty()) {
        if (log.isInfoEnabled()) log.info(startInfo());

        return;
      }
    }

    U.warn(
        log,
        "Failed to start Jetty REST server (possibly all ports in range are in use) "
            + "[firstPort="
            + initPort
            + ", lastPort="
            + lastPort
            + ']');
  }