public function work_sets_count($bucket = self::DEFAULT_BUCKET, $process_all_buckets = false)
	{
		// if asked to process all buckets, count all of them and return the count
		if ($process_all_buckets === true)
		{
			$count = 0;
			foreach ($this->buckets as $bucket_slot)
			{
				$count += count($this->work_units[$bucket_slot]);
			}
			return $count;
		}

		return count($this->work_units[$bucket]);
	}