Drupal 8: Get Block's parent Node title and full URL

themename.theme.php

<?php

use Drupal\Core\Url;

/**
 * Implements hook_preprocess_HOOK() for block.html.twig.
 */
function themename_preprocess_block(&$variables) {
  // Get Title of Block's parent Node.
  $request = \Drupal::request();
  $route_match = \Drupal::routeMatch();
  $title = \Drupal::service('title_resolver')->getTitle($request, $route_match->getRouteObject());
  $variables['node_title'] = $title;
  // Get full URL of Block's parent Node.
  $current_path = \Drupal::service('path.current')->getPath();
  $path_alias = \Drupal::service('path.alias_manager')->getAliasByPath($current_path);
  $current_url = \Drupal\Core\Url::fromUserInput($path_alias, array('absolute' => TRUE))->toString();
  $variables['abs_url'] = $current_url;
}