Symfony2 skips default_ttl setting in AppCache - symfony

Question

When I set TTLs explicitly in a controller
$response->setMaxAge(60);
$response->setSharedMaxAge(60);
everything works perfectly OK and I get the right response headers:
X-Symfony-Cache GET /hello/show/: miss, store
... and then ...
X-Symfony-Cache GET /hello/show/: stale, invalid, store
... and then ...
X-Symfony-Cache GET /hello/show/: fresh
But when I don't set TTLs explicitly in a controller and want to use default TTL settings:
class AppCache extends HttpCache {
protected function getOptions() {
return array(
'debug' => true,
'default_ttl' => 60,
'private_headers' => array('Authorization', 'Cookie'),
'allow_reload' => false,
'allow_revalidate' => false,
'stale_while_revalidate' => 2,
'stale_if_error' => 60,
);
}
}
I always get a "miss".
X-Symfony-Cache GET /hello/show/: miss
It looks like Symfony doesn't take the default_ttl setting into account. Why?

Answer 1

I found the reason. It's due to private/public reponses. The documentation states:
Public vs private Responses¶
Both gateway and proxy caches are considered "shared" caches as the
cached content is shared by more than one user. If a user-specific
response were ever mistakenly stored by a shared cache, it might be
returned later to any number of different users. Imagine if your
account information were cached and then returned to every subsequent
user who asked for their account page!
To handle this situation, every response may be set to be public or
private:
public: Indicates that the response may be cached by both private and shared caches;
private: Indicates that all or part of the response message is intended for a single user and must not be cached by a shared cache.
Symfony conservatively defaults each response to be private. To take
advantage of shared caches (like the Symfony2 reverse proxy), the
response will need to be explicitly set as public
So to make Symfony use the default_ttl setting you have to explicitly set your Response to be public like so:
$response->setPublic();