Setting TTL in Redis

[sddaniels]

It looks like there's a TTL setting available for this plugin, but it's only used for internal calculations. There is no TTL passed to Redis, so each page is cached indefinitely. That seems to be why the allkeys-lru eviction policy is recommended.

With our current automation, we're not able to easily change this eviction strategy from the default, which does not evict any keys that do not have a TTL set. Is there any reason that this plugin couldn't optionally set the TTL in Redis?

[wkhayrattee]

hey @sddaniels this ticket is dated, but curious to follow along.

Did you try this:

// Change the cache time-to-live to 10 minutes
$redis_page_cache_config['ttl'] = 600;

Or what did you end up doing?

[soulseekah]

https://github.com/pressjitsu/pj-page-cache-red/blob/master/advanced-cache.php#L642 we actually do perform a setTimeout (which is deprected as of PHP 7.2, we need to change that to expire instead). This sets the TTL for all entries being added upon shutdown.

Can we have a confirmation on this, please?

[soulseekah]

so each page is cached indefinitely

I just checked and this is true, unfortunately. We are keeping these keys indefinitely.
We'll need to discuss why this is happening.

[AndPicc]

Hello @soulseekah and thanks for this very useful drop-in.

We've been using it for a while but I just recently realised that the keys are never expired automatically, as it's mentioned in this thread. The cache is only expired and refreshed if you visit the page again, but old pages that are never visited again are lingering in the database forever...

I've been testing and trying to figure out why, but unfortunately I couldn't make it work...
could you have a look and give me a hand please?

one thing I was wondering is why are you not passing the expiration directly when setting the cache value?
somewhere like here:

pj-page-cache-red/advanced-cache.php

Line 508 in 46e7316

$redis->set( sprintf( 'pjc-%s', self::$request_hash ), $data );

thanks in advance!