class Stopwatch

ContainerAwareTraceableEventDispatcher.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Debug/ContainerAwareTraceableEventDispatcher.php

ContainerAwareTraceableEventDispatcherTest.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Tests/Debug/ContainerAwareTraceableEventDispatcherTest.php

StopwatchTest.php in drupal/core/vendor/symfony/http-kernel/Symfony/Component/HttpKernel/Tests/Debug/StopwatchTest.php

class Stopwatch {
  private $sections;
  private $activeSections;
  public function __construct() {
    $this->sections = $this->activeSections = array(
      '__root__' => new Section('__root__'),
    );
  }

  /**
   * Creates a new section or re-opens an existing section.
   *
   * @param string|null $id The id of the session to re-open, null to create a new one
   *
   * @throws \LogicException When the section to re-open is not reachable
   */
  public function openSection($id = null) {
    $current = end($this->activeSections);
    if (null !== $id && null === $current
      ->get($id)) {
      throw new \LogicException(sprintf('The section "%s" has been started at an other level and can not be opened.', $id));
    }
    $this
      ->start('__section__.child', 'section');
    $this->activeSections[] = $current
      ->open($id);
    $this
      ->start('__section__');
  }

  /**
   * Stops the last started section.
   *
   * The id parameter is used to retrieve the events from this section.
   *
   * @see getSectionEvents
   *
   * @param string $id The identifier of the section
   */
  public function stopSection($id) {
    $this
      ->stop('__section__');
    if (1 == count($this->activeSections)) {
      throw new \LogicException('There is no started section to stop.');
    }
    $this->sections[$id] = array_pop($this->activeSections)
      ->setId($id);
    $this
      ->stop('__section__.child');
  }

  /**
   * Starts an event.
   *
   * @param string $name     The event name
   * @param string $category The event category
   *
   * @return StopwatchEvent A StopwatchEvent instance
   */
  public function start($name, $category = null) {
    return end($this->activeSections)
      ->startEvent($name, $category);
  }

  /**
   * Stops an event.
   *
   * @param string $name The event name
   *
   * @return StopwatchEvent A StopwatchEvent instance
   */
  public function stop($name) {
    return end($this->activeSections)
      ->stopEvent($name);
  }

  /**
   * Stops then restarts an event.
   *
   * @param string $name The event name
   *
   * @return StopwatchEvent A StopwatchEvent instance
   */
  public function lap($name) {
    return end($this->activeSections)
      ->stopEvent($name)
      ->start();
  }

  /**
   * Gets all events for a given section.
   *
   * @param string $id A section identifier
   *
   * @return StopwatchEvent[] An array of StopwatchEvent instances
   */
  public function getSectionEvents($id) {
    return isset($this->sections[$id]) ? $this->sections[$id]
      ->getEvents() : array();
  }

}