public static function getKnownSegmentsToArchiveForSite($idSite)
    {
        $cacheId = 'KnownSegmentsToArchiveForSite' . $idSite;
        $cache   = PiwikCache::getTransientCache();
        if ($cache->contains($cacheId)) {
            return $cache->fetch($cacheId);
        }

        $segments = array();
        /**
         * Triggered during the cron archiving process to collect segments that
         * should be pre-processed for one specific site. The archiving process will be launched
         * for each of these segments when archiving data for that one site.
         *
         * This event can be used to add segments to be pre-processed for one site.
         *
         * _Note: If you just want to add a segment that is managed by the user, you should use the
         * SegmentEditor API._
         *
         * **Example**
         *
         *     Piwik::addAction('Segments.getKnownSegmentsToArchiveForSite', function (&$segments, $idSite) {
         *         $segments[] = 'country=jp;city=Tokyo';
         *     });
         *
         * @param array &$segmentsToProcess List of segment definitions, eg,
         *
         *                                      array(
         *                                          'browserCode=ff;resolution=800x600',
         *                                          'country=JP;city=Tokyo'
         *                                      )
         *
         *                                  Add segments to this array in your event handler.
         * @param int $idSite The ID of the site to get segments for.
         */
        Piwik::postEvent('Segments.getKnownSegmentsToArchiveForSite', array(&$segments, $idSite));

        $segments = array_unique($segments);

        $cache->save($cacheId, $segments);

        return $segments;
    }