Cache Clearing - rocket_clean_home_feeds() runs even when feed caching is disabled

[vmanthos]

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• Made sure you’re on the latest version ✅ (3.9.0.5)
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Describe the bug

When rocket_clean_post() runs, rocket_clean_home_feeds() will run as well, even when we are not caching the site's feeds, which is the default:

wp-rocket/inc/common/purge.php

Line 245 in 93b71be

rocket_clean_home_feeds();

On a Cloudways site, these results in sending 2 PURGE requests to their Varnish. Each of these took 2 seconds.

To Reproduce
Steps to reproduce the behavior:

1. Install WP Rocket - feeds caching is disabled by default.
2. Add log statements in rocket_clean_home_feeds().
3. Clear a post's cache to trigger rocket_clean_post().
4. Check the log.

Expected behavior

rocket_clean_home_feeds() should run only if someone has activated feed caching.

Additional context
Ticket: https://secure.helpscout.net/conversation/1539262653/270635/
Slack convo: https://wp-media.slack.com/archives/C43T1AYMQ/p1625218864433800

Backlog Grooming (for WP Media dev team use only)

• Reproduce the problem
• Identify the root cause
• Scope a solution
• Estimate the effort

[remyperona]

Since we don't have an option (anymore) for the feed cache, we don't have an easy way to detect if we should or not call the clean function.

I'm wondering though if at that point we should remove the default call of this function in our code, and instead update our helper plugin to hook on after_rocket_clean_post and call the function only when the helper is enabled.

@piotrbak what do you think?

[piotrbak]

Yes, that sounds like the best approach. Thanks @Tabrisrp !

[vmanthos]

This approach will result in feeds not being cleared, when we make the change, and will create tickets.

How about using has_filter() for wp_rocket_cache_feed which is used in the helper plugin?
https://github.com/wp-media/wp-rocket-helpers/blob/fe97245d17d5341f206de1638db87bdc0554a141/cache/wp-rocket-cache-feed/wp-rocket-cache-feed/wp-rocket-cache-feed.php#L30

if( false !=== has_filter( 'rocket_cache_reject_uri', 'wp_rocket_cache_feed') ){
   rocket_clean_home_feeds();
}

Here I am making an assumption that whoever has enabled feeds caching has done it using our helper plugin.
If there are customers who've done it differently, they will be affected by the approach I'm suggesting.

I'm guessing they will be less than those that will be affected if we add rocket_clean_home_feeds() in the helper, given that in support and in our docs we suggest using the helper.

[remyperona]

We can do that too, it's true that it will has less side-effect

[juricazuanovic]

Related: https://secure.helpscout.net/conversation/1805560493/329554/

[remyperona]

Scope a solution ✅

In rocket_clean_post(), wrap the call to rocket_clean_home_feeds() to check if the helper plugin callback is used.

if ( false !=== has_filter( 'rocket_cache_reject_uri', 'wp_rocket_cache_feed') ) {
   rocket_clean_home_feeds();
}

Estimate the effort ✅

Effort [XS]