CakePHP re-Cache content before the time end - php

Question

I have an application written in CakePHP version 1.2 and it was very slow because of the heavy and unoptimized queries to the database, this is an example of a deleas:
$pedidos_entregas = $this->Pedido->query('select pedidos.*, lojas.*, pessoas.*, formas_pagamentos.* from pedidos inner join veiculos_periodos
on pedidos.veiculos_periodo_id = veiculos_periodos.id inner join lojas
on veiculos_periodos.loja_id = lojas.id inner join pessoas
on pessoas.id = pedidos.pessoa_id inner join formas_pagamentos
on pedidos.formas_pagamento_id = formas_pagamentos.id
where
(finalizado = 1 or pedidos.id in
(
select pedido_id from status_pedidos where statu_id = 11
)
) order by entrega desc limit 200;');
Cache applied 30 minutes and much improved site performance. But when, after 30 minutes, one of the user will have to view the page slowly, to fill the cache again.
I captured the remaining time to finish each cache access controller that contains the use of the Cache.
$vencimento = file_get_contents(CACHE . 'cake_siv_financeiro_pedidos_entregas');
$vencimento = explode("\n", $vencimento);
$vencimento = $vencimento[0];
$agora = strtotime('now');
$faltam = ($vencimento - $agora)/60; //remaining time
echo $faltam;
For that, the win before the Cache 30 minutes, when missing 10 minutes or less, for example, if someone accesses the page, the cache already be updated again.
But still, a user will have to view the page slowly, because the query has to be done.
My question is: how to perform some function after the rendering of the view for the user? I want to do something like this, but this do not work
public function afterFilter()
{
parent::afterFilter();
//$this->atualizar_log();
$saida = $this->output;
$this->output = "";
ob_start();
print $saida;
flush();
ob_end_flush();
//I need that sleep after html returned to browser
sleep(500);
}
I have a second question, say I have a table sequinte:
table people
id (PK) name age
1 bob 20
2 ana 19
3 maria 50
and I run the following sql
UPDATE people SET age = 20 where id <3
 
This will affect the ID lines 1 and 2.
How, in CakePHP, after the update, grab the ids affected? (1 and 2)???
This is necessary when I delete existing caches;

Answer 1

It's not possible to execute code after a request. The best approach is to set up a cron job. You'll want to hook up a Cake Shell to cron - see http://book.cakephp.org/1.2/view/846/Running-Shells-as-cronjobs
If you can't use cron for whatever reason, consider having your clients fire an AJAX request to an action which updates the cache. This will happen after page load so there won't be a delay for the user.
edit: linked to 1.2 version of docs

Answer 2

to second question:
don't know if there is CakePHP way to do it but, you can still use mysql statement in query() method:
$sql = "SET #affids := '';
UPDATE people
SET age = 20
WHERE id < 3
AND ( SELECT #affids := CONCAT_WS(',', #affids, id) );
SELECT TRIM(LEADING ',' FROM #affids) AS affected; ";
$rs = $this->MODELNAME->query($sql);
debug($rs);
the query returns comma separated ids affected by the update.