code: public function completeRendering(Mage_Core_Block_Abstract $block)
      {
          $this->isRendering = false;
          $this->renderedCompletedAt = microtime(true);
          $this->renderedDuration += ($this->renderedCompletedAt * 1000 - $this->renderedAt * 1000);
          $this->templateFile = $block instanceof Mage_Core_Block_Template ? $block->getTemplateFile() : '';
  
          self::$endRenderingTime = $this->renderedCompletedAt;
      }
docs: Captures rendering completion for specified block
  
  @param Mage_Core_Block_Abstract $block