class TraceableViewExecutable

class TraceableViewExecutable extends ViewExecutable {
    
    /**
     * @var float
     */
    protected $render_time;
    
    /**
     * Gets the build time.
     *
     * @return float
     */
    public function getBuildTime() {
        return $this->build_time;
    }
    
    /**
     * Gets the execute time.
     *
     * @return float
     */
    public function getExecuteTime() {
        return property_exists($this, 'execute_time') ? $this->execute_time : 0.0;
    }
    
    /**
     * Gets the render time.
     *
     * @return float
     */
    public function getRenderTime() {
        return $this->render_time;
    }
    
    /**
     * {@inheritdoc}
     */
    public function render($display_id = NULL) {
        $start = microtime(TRUE);
        $this->execute($display_id);
        // Check to see if the build failed.
        if (!empty($this->build_info['fail'])) {
            return;
        }
        if (!empty($this->build_info['denied'])) {
            return;
        }
        
        /** @var \Drupal\views\Plugin\views\exposed_form\ExposedFormPluginInterface $exposed_form */
        $exposed_form = $this->display_handler
            ->getPlugin('exposed_form');
        $exposed_form->preRender($this->result);
        $module_handler = \Drupal::moduleHandler();
        // @TODO In the longrun, it would be great to execute a view without
        //   the theme system at all. See https://www.drupal.org/node/2322623.
        $active_theme = \Drupal::theme()->getActiveTheme();
        $themes = array_keys($active_theme->getBaseThemes());
        $themes[] = $active_theme->getName();
        // Check for already-cached output.
        
        /** @var \Drupal\views\Plugin\views\cache\CachePluginBase $cache */
        if (!empty($this->live_preview)) {
            $cache = Views::pluginManager('cache')->createInstance('none');
        }
        else {
            $cache = $this->display_handler
                ->getPlugin('cache');
        }
        // Run preRender for the pager as it might change the result.
        if (!empty($this->pager)) {
            $this->pager
                ->preRender($this->result);
        }
        // Initialize the style plugin.
        $this->initStyle();
        if (!isset($this->response)) {
            // Set the response so other parts can alter it.
            $this->response = new Response('', 200);
        }
        // Give field handlers the opportunity to perform additional queries
        // using the entire resultset prior to rendering.
        if ($this->style_plugin
            ->usesFields()) {
            foreach ($this->field as $id => $handler) {
                if (!empty($this->field[$id])) {
                    $this->field[$id]
                        ->preRender($this->result);
                }
            }
        }
        $this->style_plugin
            ->preRender($this->result);
        // Let each area handler have access to the result set.
        $areas = [
            'header',
            'footer',
        ];
        // Only call preRender() on the empty handlers if the result is empty.
        if (empty($this->result)) {
            $areas[] = 'empty';
        }
        foreach ($areas as $area) {
            foreach ($this->{$area} as $handler) {
                $handler->preRender($this->result);
            }
        }
        // Let modules modify the view just prior to rendering it.
        $module_handler->invokeAll('views_pre_render', [
            $this,
        ]);
        // Let the themes play too, because pre render is a very themey thing.
        foreach ($themes as $theme_name) {
            $function = $theme_name . '_views_pre_render';
            if (function_exists($function)) {
                $function($this);
            }
        }
        $this->display_handler->output = $this->display_handler
            ->render();
        $exposed_form->postRender($this->display_handler->output);
        $cache->postRender($this->display_handler->output);
        // Let modules modify the view output after it is rendered.
        $module_handler->invokeAll('views_post_render', [
            $this,
            &$this->display_handler->output,
            $cache,
        ]);
        // Let the themes play too, because post render is a very themey thing.
        foreach ($themes as $theme_name) {
            $function = $theme_name . '_views_post_render';
            if (function_exists($function)) {
                $function($this, $this->display_handler->output, $cache);
            }
        }
        $this->render_time = microtime(TRUE) - $start;
        return $this->display_handler->output;
    }

}