/**
   * Creates new HTTP requests handler.
   *
   * @param hnd Handler.
   * @param authChecker Authentication checking closure.
   * @param log Logger.
   */
  GridJettyRestHandler(
      GridRestProtocolHandler hnd, GridClosure<String, Boolean> authChecker, GridLogger log) {
    assert hnd != null;
    assert log != null;

    this.hnd = hnd;
    this.log = log;
    this.authChecker = authChecker;

    // Init default page and favicon.
    try {
      initDefaultPage();

      if (log.isDebugEnabled()) log.debug("Initialized default page.");
    } catch (IOException e) {
      U.warn(log, "Failed to initialize default page: " + e.getMessage());
    }

    try {
      initFavicon();

      if (log.isDebugEnabled())
        log.debug(
            favicon != null ? "Initialized favicon, size: " + favicon.length : "Favicon is null.");
    } catch (IOException e) {
      U.warn(log, "Failed to initialize favicon: " + e.getMessage());
    }
  }
  /**
   * @param rmtReducer Optional reducer.
   * @param rmtTransform Optional transformer.
   * @param args Arguments.
   * @return Future.
   */
  @SuppressWarnings("IfMayBeConditional")
  private <R> GridCacheQueryFuture<R> execute(
      @Nullable GridReducer<T, R> rmtReducer,
      @Nullable GridClosure<T, R> rmtTransform,
      @Nullable Object... args) {
    Collection<GridNode> nodes = nodes();

    cctx.checkSecurity(GridSecurityPermission.CACHE_READ);

    if (F.isEmpty(nodes))
      return new GridCacheQueryErrorFuture<>(
          cctx.kernalContext(),
          new GridEmptyProjectionException("There are no data nodes for cache: " + cctx.namexx()));

    if (log.isDebugEnabled())
      log.debug("Executing query [query=" + this + ", nodes=" + nodes + ']');

    if (cctx.deploymentEnabled()) {
      try {
        cctx.deploy().registerClasses(filter, rmtReducer, rmtTransform);
        cctx.deploy().registerClasses(args);
      } catch (GridException e) {
        return new GridCacheQueryErrorFuture<>(cctx.kernalContext(), e);
      }
    }

    if (subjId == null) subjId = cctx.localNodeId();

    taskHash = cctx.kernalContext().job().currentTaskNameHash();

    GridCacheQueryBean bean =
        new GridCacheQueryBean(
            this,
            (GridReducer<Object, Object>) rmtReducer,
            (GridClosure<Object, Object>) rmtTransform,
            args);

    GridCacheQueryManager qryMgr = cctx.queries();

    boolean loc = nodes.size() == 1 && F.first(nodes).id().equals(cctx.localNodeId());

    if (type == SQL_FIELDS)
      return (GridCacheQueryFuture<R>)
          (loc ? qryMgr.queryFieldsLocal(bean) : qryMgr.queryFieldsDistributed(bean, nodes));
    else
      return (GridCacheQueryFuture<R>)
          (loc ? qryMgr.queryLocal(bean) : qryMgr.queryDistributed(bean, nodes));
  }
  /** {@inheritDoc} */
  @Override
  public void handle(String target, Request req, HttpServletRequest srvReq, HttpServletResponse res)
      throws IOException, ServletException {
    if (log.isDebugEnabled())
      log.debug("Handling request [target=" + target + ", req=" + req + ", srvReq=" + srvReq + ']');

    if (target.startsWith("/gridgain")) {
      processRequest(target, srvReq, res);

      req.setHandled(true);
    } else if (target.startsWith("/favicon.ico")) {
      if (favicon == null) {
        res.setStatus(HttpServletResponse.SC_NOT_FOUND);

        req.setHandled(true);

        return;
      }

      res.setStatus(HttpServletResponse.SC_OK);

      res.setContentType("image/x-icon");

      res.getOutputStream().write(favicon);
      res.getOutputStream().flush();

      req.setHandled(true);
    } else {
      if (dfltPage == null) {
        res.setStatus(HttpServletResponse.SC_NOT_FOUND);

        req.setHandled(true);

        return;
      }

      res.setStatus(HttpServletResponse.SC_OK);

      res.setContentType("text/html");

      res.getWriter().write(dfltPage);
      res.getWriter().flush();

      req.setHandled(true);
    }
  }
  /**
   * @param res Query result.
   * @param err Error or {@code null} if query executed successfully.
   * @param startTime Start time.
   * @param duration Duration.
   */
  public void onExecuted(Object res, Throwable err, long startTime, long duration) {
    boolean fail = err != null;

    // Update own metrics.
    metrics.onQueryExecute(duration, fail);

    // Update metrics in query manager.
    cctx.queries().onMetricsUpdate(duration, fail);

    if (log.isDebugEnabled())
      log.debug(
          "Query execution finished [qry="
              + this
              + ", startTime="
              + startTime
              + ", duration="
              + duration
              + ", fail="
              + fail
              + ", res="
              + res
              + ']');
  }
  /**
   * Process HTTP request.
   *
   * @param act Action.
   * @param req Http request.
   * @param res Http response.
   */
  private void processRequest(String act, HttpServletRequest req, HttpServletResponse res) {
    res.setContentType("application/json");
    res.setCharacterEncoding("UTF-8");

    GridRestCommand cmd = command(req);

    if (cmd == null) {
      res.setStatus(HttpServletResponse.SC_BAD_REQUEST);

      return;
    }

    if (!authChecker.apply(req.getHeader("X-Signature"))) {
      res.setStatus(HttpServletResponse.SC_UNAUTHORIZED);

      return;
    }

    GridRestResponse cmdRes;

    Map<String, Object> params = parameters(req);

    try {
      GridRestRequest cmdReq = createRequest(cmd, params, req);

      if (log.isDebugEnabled()) log.debug("Initialized command request: " + cmdReq);

      cmdRes = hnd.handle(cmdReq);

      if (cmdRes == null)
        throw new IllegalStateException("Received null result from handler: " + hnd);

      byte[] sesTok = cmdRes.sessionTokenBytes();

      if (sesTok != null) cmdRes.setSessionToken(U.byteArray2HexString(sesTok));

      res.setStatus(HttpServletResponse.SC_OK);
    } catch (Exception e) {
      res.setStatus(HttpServletResponse.SC_OK);

      U.error(log, "Failed to process HTTP request [action=" + act + ", req=" + req + ']', e);

      cmdRes = new GridRestResponse(STATUS_FAILED, e.getMessage());
    } catch (Throwable e) {
      U.error(log, "Failed to process HTTP request [action=" + act + ", req=" + req + ']', e);

      throw e;
    }

    JsonConfig cfg = new GridJettyJsonConfig();

    // Workaround for not needed transformation of string into JSON object.
    if (cmdRes.getResponse() instanceof String)
      cfg.registerJsonValueProcessor(cmdRes.getClass(), "response", SKIP_STR_VAL_PROC);

    if (cmdRes.getResponse() instanceof GridClientTaskResultBean
        && ((GridClientTaskResultBean) cmdRes.getResponse()).getResult() instanceof String)
      cfg.registerJsonValueProcessor(cmdRes.getResponse().getClass(), "result", SKIP_STR_VAL_PROC);

    JSON json;

    try {
      json = JSONSerializer.toJSON(cmdRes, cfg);
    } catch (JSONException e) {
      U.error(log, "Failed to convert response to JSON: " + cmdRes, e);

      json = JSONSerializer.toJSON(new GridRestResponse(STATUS_FAILED, e.getMessage()), cfg);
    }

    try {
      if (log.isDebugEnabled())
        log.debug("Parsed command response into JSON object: " + json.toString(2));

      res.getWriter().write(json.toString());

      if (log.isDebugEnabled())
        log.debug(
            "Processed HTTP request [action=" + act + ", jsonRes=" + cmdRes + ", req=" + req + ']');
    } catch (IOException e) {
      U.error(log, "Failed to send HTTP response: " + json.toString(2), e);
    }
  }