3.17 - Make depth and type of LRC candidates filterable

[MathieuLamiot]

Context Currently, PHP adds hashes to LRC candidates up to depth 2 inside the body. Note that the depth and type are currently also checked by the beacon, but it should not and will be removed as part of https://github.com/wp-media/rocket-scripts/issues/25 Until then, it is possible to implement this issue and test it by checking what elements get the hash added, but they might not be picked up correctly by the beacon, hence not be in DB at the end of the visit.

Expected behavior We must provide a filter to change how deep we look for eligible LRC candidates to add the hashes to. We must provide a filter to change the list of eligible element types for LRC candidates.

Acceptance Criteria

• The filter is safeguarded to only accept strictly positive integers (for depth) and array of string for element types.
• With the default value, clear the cache and remove the Performance Hints data. Visit a page and check some elements that don't have the hash and that have the right type (typically div), but their parents have (so depth = 3) the hash. Then increase the depth with the filter and repeat. Those elements must have the hash.
• With the default value, clear the cache and remove the Performance Hints data. Visit a page and check some elements that don't have the hash because they are not the right type (but at the right depth). Then change the list of elibigle elements to include those elements and repeat. Those elements must have the hash

Proposed grooming I think the solution can be:

The constant here:

$this->add_hash_to_element( $body, 2 );

in /Users/mathieu/Documents/Github/wp-rocket/inc/Engine/Optimization/LazyRenderContent/Frontend/Processor/SimpleHtmlDom.php and /Users/mathieu/Documents/Github/wp-rocket/inc/Engine/Optimization/LazyRenderContent/Frontend/Processor/Dom.php

Same thing for the $skip_tags in:

/Users/mathieu/Documents/Github/wp-rocket/inc/Engine/Optimization/LazyRenderContent/Frontend/Processor/SimpleHtmlDom.php and /Users/mathieu/Documents/Github/wp-rocket/inc/Engine/Optimization/LazyRenderContent/Frontend/Processor/Dom.php /Users/mathieu/Documents/Github/wp-rocket/inc/Engine/Optimization/LazyRenderContent/Frontend/Processor/Regex.php

Effort: XS

[jeawhanlee]

@MathieuLamiot I'm not sure to understand the grooming completely to help me review, please could you elaborate. I can see how we can have a depth filter for DOM & SimpleDOM but how so for REGEX, it's not clear for me.

[MathieuLamiot]

For regex, we don't. In case of Regex processor, identifying depth was too complex hence discarded. Thisbis why the depth parameter is only for the 2 other processors. The list of eligible elements is used by the 3 processors though.

Therefore, depth control and related ACs don't apply to regex processor

Note that we will likely remove SimpleDom and Regex before the release (To be discussed and confirmed next week)

[jeawhanlee]

LGTM then...