CTaskTimerManager::start

public function start($taskId)
{
	global $CACHE_MANAGER;

	// Stop timer of user (if it is run)
	$this->stop();

	$task = CTaskItem::getInstance($taskId, $this->userId);

	try
	{
		$taskData = $task->getData(false);
	}
	catch (TasksException $e)
	{
		return false;
	}

	if (!$task->checkAccess(ActionDictionary::ACTION_TASK_TIME_TRACKING))
	{
		return false;
	}

	// Run timer for given task
	$timer = CTaskTimerCore::start($this->userId, $taskId);

	$this->cachedLastTimer = null;

	$affectedUsers = array_unique(
		array_merge(
			[$this->userId, $taskData['RESPONSIBLE_ID']],
			(array)$taskData['ACCOMPLICES']
		)
	);
	foreach ($affectedUsers as $userId)
	{
		$CACHE_MANAGER->ClearByTag("tasks_user_{$userId}");
	}

	if ($timer === false)
	{
		return false;
	}

	// Add task to day plan
	$currentUserId = User::getId();
	if ($currentUserId && ($currentUserId === $this->userId))
	{
		$dayPlanTasks = CTaskPlannerMaintance::getCurrentTasksList();
		if (!in_array($taskId, $dayPlanTasks))
		{
			CTaskPlannerMaintance::plannerActions(['add' => [$taskId]]);
		}
	}

	if ((int)$taskData['REAL_STATUS'] !== Status::IN_PROGRESS)
	{
		if ($task->checkAccess(ActionDictionary::ACTION_TASK_START))
		{
			$task->startExecution();
		}
		elseif ($task->checkAccess(ActionDictionary::ACTION_TASK_RENEW))
		{
			$task->renew();
		}
	}

	PushService::addEvent(
		$this->userId,
		[
			'module_id' => 'tasks',
			'command' => PushCommand::TASK_TIMER_STARTED,
			'params' => [
				'taskId' => $taskId,
				'timeElapsed' => (int)$taskData['TIME_SPENT_IN_LOGS'] + (time() - $timer['TIMER_STARTED_AT']),
			],
		]
	);

	return $timer;
}