Cloudflare purged several times on post update

[WordPresseur]

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Describe the bug
When a post is updated, Cloudflare cache is purged 3 times:

1. via WP_Rocket/ThirdParty/Plugins/CDN/Cloudflare: purge_cloudflare_partial
2. via WP_Rocket/ThirdParty/Plugins/CDN/Cloudflare: purge_cloudflare_post
3. via official Cloudflare plugin: https://github.com/cloudflare/Cloudflare-WordPress/blob/34852c089cb121860ecabd485120eb1c2fc4a286/cloudflare.loader.php#L113
   (or on the WordPress Repo: https://plugins.trac.wordpress.org/browser/cloudflare/trunk/cloudflare.loader.php#L113)

Expected behavior
Cloudflare cache should only be purged once.

Additional context
Ticket: https://secure.helpscout.net/conversation/2273098471/424855?folderId=1213662

Backlog Grooming (for WP Media dev team use only)

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

[piotrbak]

Not sure what will we be able to improve here, as per our past discussions. Let's revisit this part of the code and try to do the following:

Prerequisites: WP Rocket enabled, CF plugin enabled, APO activated for the domain

Acceptance Criteria:

1. When updating the post, only two requests are being sent to APO (our and CF official one).*
2. No regressions in the Purge URL and Purge Whole Cache parts, only one request should be sent too.

• We can't make it to only one request for now, as CF Official plugin has a bug. We'll fix this whenever it's possible

[Tabrisrp]

We could remove the hook on after_clean_post, since rocket_clean_post() also uses rocket_clean_files(), so it will go through after_clean_files anyway.

If we remove our hooks entirely, it will allow to have only one request, but it might not cover all URLs to clean, as the CF plugin is not clearing as much as us. And as discussed earlier, their hooks are not implemented correctly so we can't add additional data to them.

[piotrbak]

@Tabrisrp I'd split this ticket into two then:

1. Removal of the after_clean_post hook
2. Creating PR related to the Cloudflare + maybe adding a PR in their repository to speed up the process.

What do you think?

[piotrbak]

So, in this PR we'll only remove the after_clean_post hook, I'll create an issue for the second iteration

[Tabrisrp]

I would not have high expectations for the PR on their side, there is already an issue about it that was not solved since at least a couple years.

[vmanthos]

@Tabrisrp @piotrbak While doing exploratory for this issue, I found that rocket_clean_post() and rocket_clean_files() are called twice every time a post is updated. The same goes for after_rocket_clean_files. Although I haven't tested this with the PR this is likely involved in increasing the number of requests towards Cloudflare. Further R & D is required.

For future reference, the reason those functions run twice is because clean_post_cache fires twice.
Here is the log - wp_debug_backtrace_summary includes the backtrace for the clean_post_cache() method using wp_debug_backtrace_summary():

clean_post_cache() run
wp_debug_backtrace_summary: 'require(\'wp-blog-header.php\'), wp, WP->main, WP->parse_request, do_action_ref_array(\'parse_request\'), WP_Hook->do_action, WP_Hook->apply_filters, rest_api_loaded, WP_REST_Server->serve_request, WP_REST_Server->dispatch, WP_REST_Server->respond_to_request, WP_REST_Posts_Controller->update_item, wp_update_post, wp_insert_post, clean_post_cache'

13:12:45 clean_post_cache fired
===== rocket_clean_files() =====
array (
  0 => 'https://wprocketest.test/hello-world',
  1 => 'https://wprocketest.test/blog',
  2 => 'https://wprocketest.test/author/vasilis/',
)

===== rocket_clean_post() =====
array (
  0 => 'https://wprocketest.test/hello-world',
  1 => 'https://wprocketest.test/blog',
  2 => 'https://wprocketest.test/author/vasilis/',
)

clean_post_cache run
wp_debug_backtrace_summary: 'edit_post, wp_update_post, wp_insert_post, clean_post_cache'


13:12:45 clean_post_cache fired
===== rocket_clean_files() =====
array (
  0 => 'https://wprocketest.test/hello-world',
  1 => 'https://wprocketest.test/blog',
  2 => 'https://wprocketest.test/post-53',
  3 => 'https://wprocketest.test/post-2',
  4 => 'https://wprocketest.test/gallery-layout',
  5 => 'https://wprocketest.test/author/vasilis/',
)

===== rocket_clean_post() =====
array (
  0 => 'https://wprocketest.test/hello-world',
  1 => 'https://wprocketest.test/blog',
  2 => 'https://wprocketest.test/post-53',
  3 => 'https://wprocketest.test/post-2',
  4 => 'https://wprocketest.test/gallery-layout',
  5 => 'https://wprocketest.test/author/vasilis/',
)