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Add object caching for WP_Theme_JSON::compute_style_properties #5567

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Add object caching for WP_Theme_JSON::compute_style_properties #5567

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85e9170
Add object caching for `WP_Theme_JSON::compute_style_properties`
Oct 24, 2023
7450d26
The values of the args are only useful for the cache key
Oct 24, 2023
c9b36ea
Deal with cache before updating `$properties`
Oct 24, 2023
dd8c83e
Only use cache if not in dev mode for theme. Ensure we do not process…
Nov 3, 2023
7d97433
Address PHPCS warning. It really does not matter if the value of `$pr…
Nov 3, 2023
bd6f08c
Merge branch 'WordPress:trunk' into add/object-cache-compute-style-pr…
pereirinha Jan 4, 2024
2377348
Remove unecessary dev mode check for cache
Jan 4, 2024
d707a79
Add the global settings to the cache key recipe, so that when it chan…
Jan 4, 2024
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11 changes: 11 additions & 0 deletions src/wp-includes/class-wp-theme-json.php
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Original file line number Diff line number Diff line change
Expand Up @@ -1934,6 +1934,15 @@ protected static function compute_style_properties( $styles, $settings = array()
return $declarations;
}

// The global settings can include dynamic data related to typography. We need evaluate it so that the cache is invalidated when it changes.
$args = array( func_get_args(), wp_get_global_settings() ); // phpcs:ignore PHPCompatibility.FunctionUse.ArgumentFunctionsReportCurrentValue.Changed
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@oandregal oandregal Jan 15, 2024 •
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The way the theme.json code is organized is as follows:

  1. WP_Theme_JSON: private class that deals with a theme.json structure. It doesn't depend on anything else.
  2. WP_Theme_JSON_Resolver: private class that pulls data (theme.json files, theme.json from database) and merges it together appropriately (get_merged_data). It depends on the WP_Theme_JSON class.
  3. Public API: functions such as wp_get_global_settings, wp_get_global_styles, etc. They use and depend on the two previous private classes.

By using a public function such as wp_get_global_settings in the WP_Theme_JSON class, this code is creating a circular dependency. This code is saying: when processing any theme.json structure, read all existing theme.json (core, blocks, theme, user) first.

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@joemcgill joemcgill Jan 17, 2024

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Thanks for the feedback @oandregal. This makes perfect sense. I think we would either need to add the caching to the public function that relies on WP_Theme_JSON::compute_style_properties or find a different approach to invalidation within WP_Theme_JSON.

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@pereirinha pereirinha Jan 17, 2024

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Thanks for the feedback @oandregal. I'll have a closer look at this

$cache_key = 'compute_style_properties_' . md5( wp_json_encode( $args ) );
Comment on lines +1938 to +1939
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@joemcgill joemcgill Jan 8, 2024

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Suggestion/nitpick: rename $args to $cach_args for readability.

Suggested change
$args = array( func_get_args(), wp_get_global_settings() ); // phpcs:ignore PHPCompatibility.FunctionUse.ArgumentFunctionsReportCurrentValue.Changed
$cache_key = 'compute_style_properties_' . md5( wp_json_encode( $args ) );
$cache_args = array( func_get_args(), wp_get_global_settings() ); // phpcs:ignore PHPCompatibility.FunctionUse.ArgumentFunctionsReportCurrentValue.Changed
$cache_key = 'compute_style_properties_' . md5( wp_json_encode( $cache_args ) );

$cache = wp_cache_get( $cache_key, 'wp-styles' );
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@joemcgill joemcgill Jan 8, 2024

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Rather than introducing a new cache group, I think this should be a part of the existing theme_json group. Would need to change it below where this cache value is set, as well.

Suggested change
$cache = wp_cache_get( $cache_key, 'wp-styles' );
$cache = wp_cache_get( $cache_key, 'theme_json' );


if ( $cache ) {
return $cache;
}

$root_variable_duplicates = array();

foreach ( $properties as $css_property => $value_path ) {
Expand Down Expand Up @@ -2000,6 +2009,8 @@ protected static function compute_style_properties( $styles, $settings = array()
}
}

wp_cache_set( $cache_key, $declarations, 'wp-styles', DAY_IN_SECONDS );
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@joemcgill joemcgill Jan 8, 2024

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I'm unsure about the best expiration time here. If there is a side effect that we've not accounted for in the cache key value, showing stale styles for a full day without flushing the cache is pretty long. Maybe limiting this to once an hour for now would be safer?

Suggested change
wp_cache_set( $cache_key, $declarations, 'wp-styles', DAY_IN_SECONDS );
wp_cache_set( $cache_key, $declarations, 'theme_json', HOUR_IN_SECONDS );

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@spacedmonkey spacedmonkey Feb 5, 2024

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Theme json is a none presient cache, so there is no need for an expiry here.


return $declarations;
}

Expand Down