Clear the cache of certain language will clear the whole cache in some cases

[Mai-Saad]

Before submitting an issue please check that you’ve completed the following steps:

• Made sure you’re on the latest version => 3.12.3.1
• Used the search feature to ensure that the bug hasn’t been reported before

Describe the bug
Clearing the cache of one language will clear the whole cache

To Reproduce
Precondition:

• WPML language format using qs i.e Language name added as a parameter (https://rocketlabsqa.ovh?lang=ar - Arabic)
• Website has 3 languages
• The shop page is set
  Steps to reproduce the behavior:

1. Install and activate WPR
2. Visit the Product and shop page in 3 different languages => pages are cached and completed in preload table
3. Clear cache of 1 language i.e AR
4. All cache was cleared

Expected behavior
Clear only affected language and not clear the whole cache

Screenshots
If applicable, add screenshots to help explain your problem.

Screencast.2022-11-22.09.46.21.mp4

Screencast.2022-11-22.09.46.21.mp4

Additional context
Add any other context about the problem here.

• Same happened on 3.11.5
• Sometimes, after step 3, the shop page gets unset automatically when we edit the product
• Other setups for WPML shall be validated
• WPML Version 4.5.8, WooCommerce Version 7.1.0, WCML Version 5.0.2

Backlog Grooming (for WP Media dev team use only)

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

[vmanthos]

We are ignoring query strings when clearing the cache and keep only the path:

wp-rocket/inc/functions/files.php

Line 758 in 5ddfb40

foreach ( _rocket_get_cache_dirs( $parsed_url['host'], $cache_path ) as $dir ) {

So:

• https://vasilis.rocketlabsqa.ovh/?lang=el
• https://vasilis.rocketlabsqa.ovh/?lang=en
  are treated like https://vasilis.rocketlabsqa.ovh/

We will likely need to change how the cache is stored when $lang is used. For example:

• cache/wp-rocket/example.com/#lang=el should store all the el URLs.
• cache/wp-rocket/example.com/#lang=en should store all the en URLs, etc.

Things will be more complicated when more than one query string is used/cached, e.g. /about-us?lang=el&location=Greece.
In such a case, we could store the cache like this:

• cache/wp-rocket/example.com/#lang=el/about-us#location=Greece

To make things worse there is inconsistent behavior depending on whether permalinks have a trailing / or not.
For /about-us?lang=el :

• with a / we'll store its cache in a subfolder of the page to cache/wp-rocket/example.com/about-us/#lang=el
• without a / the cache will be stored to: cache/wp-rocket/example.com/about-us#lang=el

This likely needs to be tackled as well.

[Mai-Saad]

Some exploratory test note(s) on the same env (may need new GH):
1- After a fresh install of WPR, language qs folders are fetched only for the home page by strange names (while Home is set to the latest posts or specific page), if we clear and preload the cache, it will be removed
=> on 3.12.3.1 and 3.12.2.1 but not on 3.11.5

2- Even on newlabs (without WPML), visiting URLs with in-progress status while a separate mobile cache is enabled, will result in completed status although no mobile version of the cache exists in the cache folder
3- Preload is not changing the status of paginated pages after editing any post inside it although, the edited post, home, and page folder were already deleted from the cache (not only prev/next pagination)

[piotrbak]

To consider when fixing:

• ​​Cleaning the front page cache, doesn't clear cached homepage #lang folders #2983
• Query string version of the homepage is not cleared with rocket_clean_home #3444

[Mai-Saad]

on 3.15.2, Can see that clearing the cache of a specific language, will clear the whole cache except for this language (to the home page) and will change the language switch at admin to that specific language