public void start()

in tajo-core/tajo-core-backend/src/main/java/org/apache/tajo/webapp/HttpServer.java [280:374]
89 lines of code
20 McCabe index (conditional complexity)

  public void start() throws IOException {
    try {
      if (listenerStartedExternally) { // Expect that listener was started
                                       // securely
        if (listener.getLocalPort() == -1) // ... and verify
          throw new Exception("Exepected webserver's listener to be started "
              + "previously but wasn't");
        // And skip all the port rolling issues.
        webServer.start();
      } else {
        int port;
        int oriPort = listener.getPort(); // The original requested port
        while (true) {
          try {
            port = webServer.getConnectors()[0].getLocalPort();
            LOG.debug("Port returned by webServer.getConnectors()[0]."
                + "getLocalPort() before open() is " + port
                + ". Opening the listener on " + oriPort);
            listener.open();
            port = listener.getLocalPort();
            LOG.debug("listener.getLocalPort() returned "
                + listener.getLocalPort()
                + " webServer.getConnectors()[0].getLocalPort() returned "
                + webServer.getConnectors()[0].getLocalPort());
            // Workaround to handle the problem reported in HADOOP-4744
            if (port < 0) {
              Thread.sleep(100);
              int numRetries = 1;
              while (port < 0) {
                LOG.warn("listener.getLocalPort returned " + port);
                if (numRetries++ > MAX_RETRIES) {
                  throw new Exception(" listener.getLocalPort is returning "
                      + "less than 0 even after " + numRetries + " resets");
                }
                for (int i = 0; i < 2; i++) {
                  LOG.info("Retrying listener.getLocalPort()");
                  port = listener.getLocalPort();
                  if (port > 0) {
                    break;
                  }
                  Thread.sleep(200);
                }
                if (port > 0) {
                  break;
                }
                LOG.info("Bouncing the listener");
                listener.close();
                Thread.sleep(1000);
                listener.setPort(oriPort == 0 ? 0 : (oriPort += 1));
                listener.open();
                Thread.sleep(100);
                port = listener.getLocalPort();
              }
            } // Workaround end
            LOG.info("Jetty bound to port " + port);
            webServer.start();
            break;
          } catch (IOException ex) {
            // if this is a bind exception,
            // then try the next port number.
            if (ex instanceof BindException) {
              if (!findPort) {
                BindException be = new BindException("Port in use: "
                    + listener.getHost() + ":" + listener.getPort());
                be.initCause(ex);
                throw be;
              }
            } else {
              LOG.info("HttpServer.start() threw a non Bind IOException");
              throw ex;
            }
          } catch (MultiException ex) {
            LOG.info("HttpServer.start() threw a MultiException");
            throw ex;
          }
          listener.setPort((oriPort += 1));
        }
      }
      // Make sure there is no handler failures.
      Handler[] handlers = webServer.getHandlers();
      for (int i = 0; i < handlers.length; i++) {
        if (handlers[i].isFailed()) {
          throw new IOException(
              "Problem in starting http server. Server handlers failed");
        }
      }
    } catch (IOException e) {
      throw e;
    } catch (InterruptedException e) {
      throw (IOException) new InterruptedIOException(
          "Interrupted while starting HTTP server").initCause(e);
    } catch (Exception e) {
      throw new IOException("Problem starting http server", e);
    }
  }