public void doGet()

in tez-common/src/main/java/org/apache/tez/common/web/ProfileServlet.java [159:301]
130 lines of code
22 McCabe index (conditional complexity)

  public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/plain; charset=UTF-8");
    PrintStream out = new PrintStream(response.getOutputStream(), false, "UTF-8");
    if (!HttpServer2.isInstrumentationAccessAllowed(this.getServletContext(), request, response)) {
      response.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
      setResponseHeader(response);
      out.println("Unauthorized: Instrumentation access is not allowed!");
      out.close();
      return;
    }

    // make sure async profiler home is set
    if (asyncProfilerHome == null || asyncProfilerHome.trim().isEmpty()) {
      response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
      setResponseHeader(response);
      out.println("ASYNC_PROFILER_HOME env is not set");
      out.close();
      return;
    }

    // if pid is explicitly specified, use it else default to current process
    pid = getInteger(request, "pid", pid);
    // if pid is not specified in query param and if current process pid cannot be determined
    if (pid == null) {
      response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
      setResponseHeader(response);
      out.println("'pid' query parameter unspecified or unable to determine PID of current process.");
      out.close();
      return;
    }

    final int duration = getInteger(request, "duration", DEFAULT_DURATION_SECONDS);
    final Output output = getOutput(request);
    final Event event = getEvent(request);
    final Long interval = getLong(request, "interval");
    final Integer jstackDepth = getInteger(request, "jstackdepth", null);
    final Long bufsize = getLong(request, "bufsize");
    final boolean thread = request.getParameterMap().containsKey("thread");
    final boolean simple = request.getParameterMap().containsKey("simple");
    final Integer width = getInteger(request, "width", null);
    final Integer height = getInteger(request, "height", null);
    final Double minwidth = getMinWidth(request);
    final boolean reverse = request.getParameterMap().containsKey("reverse");
    final String method = request.getParameter("method");

    if (request.getParameter("event") != null && method != null) {
      response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
      setResponseHeader(response);
      response.getWriter().write("Event and method aren't allowed to be both used in the same request.");
      return;
    }

    if (process == null || !process.isAlive()) {
      try {
        int lockTimeoutSecs = 3;
        if (profilerLock.tryLock(lockTimeoutSecs, TimeUnit.SECONDS)) {
          try {
            File outputFile = new File(OUTPUT_DIR,
                "async-prof-pid-" + pid + "-"
                    + (method == null ? event.name().toLowerCase() : method) + "-" + ID_GEN.incrementAndGet() + "."
                    + output.name().toLowerCase());
            List<String> cmd = new ArrayList<>();
            cmd.add(getProfilerScriptPath());
            cmd.add("-e");
            cmd.add(method == null ? event.getInternalName() : method);
            cmd.add("-d");
            cmd.add("" + duration);
            cmd.add("-o");
            cmd.add(output.name().toLowerCase());
            cmd.add("-f");
            cmd.add(outputFile.getAbsolutePath());
            if (interval != null) {
              cmd.add("-i");
              cmd.add(interval.toString());
            }
            if (jstackDepth != null) {
              cmd.add("-j");
              cmd.add(jstackDepth.toString());
            }
            if (bufsize != null) {
              cmd.add("-b");
              cmd.add(bufsize.toString());
            }
            if (thread) {
              cmd.add("-t");
            }
            if (simple) {
              cmd.add("-s");
            }
            if (width != null) {
              cmd.add("--width");
              cmd.add(width.toString());
            }
            if (height != null) {
              cmd.add("--height");
              cmd.add(height.toString());
            }
            if (minwidth != null) {
              cmd.add("--minwidth");
              cmd.add(minwidth.toString());
            }
            if (reverse) {
              cmd.add("--reverse");
            }
            cmd.add(pid.toString());
            process = new ProcessBuilder(cmd).start();

            // set response and set refresh header to output location
            setResponseHeader(response);
            response.setStatus(HttpServletResponse.SC_ACCEPTED);
            String relativeUrl = "/prof-output";
            // to avoid auto-refresh by ProfileOutputServlet, refreshDelay can be specified via url param
            int refreshDelay = getInteger(request, "refreshDelay", 0);
            // instead of sending redirect, set auto-refresh so that browsers will refresh with redirected url
            response.setHeader("Refresh", (duration + refreshDelay) + "; URL=" + relativeUrl + '?'
                + ProfileOutputServlet.FILE_QUERY_PARAM + '=' + outputFile.getName());

            out.println("Profiled PID: " + pid);
            out.println("Started [" + event.getInternalName()
                + "] profiling. This page will automatically redirect to "
                + relativeUrl + " after " + duration + " seconds.\n\ncommand:\n" + Joiner.on(" ").join(cmd));
            out.flush();
          } finally {
            profilerLock.unlock();
          }
        } else {
          setResponseHeader(response);
          response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
          out.println("Unable to acquire lock. Another instance of profiler might be running.");
          LOG.warn("Unable to acquire lock in {} seconds. Another instance of profiler might be running.",
              lockTimeoutSecs);
        }
      } catch (InterruptedException e) {
        LOG.warn("Interrupted while acquiring profile lock.", e);
        response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
      }
    } else {
      setResponseHeader(response);
      response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
      out.println("Another instance of profiler is already running.");
    }
    out.close();
  }