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<?php |
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namespace ABlocks\Performance; |
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|
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if ( ! defined( 'ABSPATH' ) ) { |
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exit; |
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} |
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|
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use ABlocks\Helper; |
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use ABlocks\Classes\FileUpload; |
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|
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/** |
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* Performance Suite — consolidate render-blocking inline CSS into cached files. |
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* |
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* Block themes emit a large amount of inline CSS into <head>: global styles, |
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* the block library, and one <style> per core block used on the page. Measured |
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* on Twenty Twenty-Four, that is ~43 KB across 20 blocks — around 40% of the |
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* document — and none of it can be reused by the browser across navigations, |
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* because it is embedded in the HTML rather than fetched as a file. |
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* |
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* This moves those blocks into content-addressed files under uploads so the |
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* browser caches them once, and every cached HTML page on disk shrinks by the |
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* same amount. |
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* |
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* ## Why per contiguous run, and not one bundle |
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* |
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* WordPress prints each stylesheet's <link> followed by its own inline <style>, |
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* so the inline blocks are *interleaved* with <link> tags — on the reference |
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* page they form 7 separate runs, not one. Concatenating all of them into a |
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* single file would move CSS across those <link> boundaries and silently |
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* reorder the cascade, which is exactly the class of bug that is impossible to |
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* attribute later. |
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* |
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* So each maximal run of adjacent <style> blocks is replaced, in place, by one |
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* <link> to a file containing exactly that run's CSS in its original order. The |
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* resulting cascade is byte-for-byte equivalent to what WordPress emitted. |
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* |
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* Runs below a byte threshold are left inline: below roughly a couple of KB a |
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* separate request costs more than the bytes saved, which is the same reasoning |
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* behind the existing `perf_inline_css` option. |
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* |
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* File names are a hash of their contents, so they are immutable and never need |
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* invalidating — a change in the CSS simply produces a different file. See |
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* docs/PAGE-CACHE-PLAN.md. |
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*/ |
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class StyleConsolidator { |
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|
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const DIR_NAME = 'consolidated-css'; |
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|
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/** |
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* Default minimum run size, in bytes, worth externalising. |
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*/ |
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const DEFAULT_MIN_BYTES = 2048; |
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|
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public static function init() { |
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if ( is_admin() ) { |
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return; |
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} |
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|
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$enabled = (bool) apply_filters( |
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'ablocks/perf/perf_consolidate_css', |
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(bool) Helper::get_settings( 'perf_consolidate_css', false ) |
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); |
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if ( ! $enabled ) { |
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return; |
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} |
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|
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// Never reshape the document for a logged-in editor previewing the |
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// frontend — consistent with the rest of the Performance Suite. |
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if ( is_user_logged_in() && current_user_can( 'edit_posts' ) |
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&& (bool) apply_filters( 'ablocks/perf/bypass_optimizations_for_editors', true ) ) { |
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return; |
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} |
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|
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$self = new self(); |
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|
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// Priority 1 puts this buffer *inside* PageCache's (priority 0). Nested |
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// buffers flush inner-first, so consolidation happens before the page |
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// cache sees the output — meaning what gets written to disk is the |
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// already-consolidated document, not the original. |
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add_action( 'template_redirect', [ $self, 'start_buffer' ], 1 ); |
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} |
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|
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/** |
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* Begin capturing output. |
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*/ |
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public function start_buffer() { |
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if ( is_feed() || is_robots() || is_trackback() ) { |
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return; |
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} |
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ob_start( [ $this, 'process' ] ); |
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} |
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|
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/** |
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* Rewrite the document head, replacing large runs of inline CSS with links. |
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* |
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* Must never throw and must always return usable HTML: a failure here should |
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* cost the optimisation, not the page. |
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* |
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* @param string $html Buffered output. |
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* @return string |
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*/ |
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public function process( $html ) { |
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if ( ! is_string( $html ) || '' === $html ) { |
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return $html; |
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} |
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|
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try { |
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$head_end = stripos( $html, '</head>' ); |
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if ( false === $head_end ) { |
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return $html; |
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} |
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|
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$head = substr( $html, 0, $head_end ); |
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$rest = substr( $html, $head_end ); |
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|
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$runs = $this->find_runs( $head ); |
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if ( empty( $runs ) ) { |
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return $html; |
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} |
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|
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$min = (int) apply_filters( |
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'ablocks/perf/consolidate_css/min_bytes', |
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(int) Helper::get_settings( 'perf_consolidate_css_min', self::DEFAULT_MIN_BYTES ) |
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); |
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|
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// Replace from the end backwards so earlier offsets stay valid. |
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foreach ( array_reverse( $runs ) as $run ) { |
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if ( strlen( $run['css'] ) < $min ) { |
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continue; |
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} |
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$url = $this->store_css( $run['css'] ); |
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if ( null === $url ) { |
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continue; |
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} |
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$tag = '<link rel="stylesheet" href="' . esc_url( $url ) . '" media="all" />'; |
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$head = substr_replace( $head, $tag, $run['start'], $run['end'] - $run['start'] ); |
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} |
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|
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return $head . $rest; |
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} catch ( \Throwable $e ) { |
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if ( defined( 'WP_DEBUG' ) && WP_DEBUG ) { |
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error_log( 'aBlocks style consolidator: ' . $e->getMessage() ); // phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log |
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} |
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return $html; |
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}//end try |
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} |
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|
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/** |
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* Locate maximal runs of adjacent <style> blocks within the head. |
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* |
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* Two blocks belong to the same run only when nothing but whitespace sits |
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* between them. Anything else — most importantly a <link> — ends the run, |
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* because merging across it would change the cascade. |
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* |
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* @param string $head Document head. |
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* @return array<int, array{start:int, end:int, css:string}> |
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*/ |
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private function find_runs( $head ) { |
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// Only tags carrying an id are considered: those are the ones WordPress |
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// generates from wp_add_inline_style(). A bare <style> is more likely to |
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// be hand-written critical CSS that a theme placed deliberately, and |
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// moving it into a file would defeat its purpose. |
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$pattern = '#<style[^>]*\bid=["\']([^"\']+)["\'][^>]*>(.*?)</style>#is'; |
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if ( ! preg_match_all( $pattern, $head, $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER ) ) { |
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return []; |
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} |
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|
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$skip = (array) apply_filters( 'ablocks/perf/consolidate_css/skip_handles', [] ); |
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|
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$runs = []; |
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$current = null; |
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$prev_end = null; |
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|
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foreach ( $matches as $match ) { |
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$tag = $match[0][0]; |
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$start = $match[0][1]; |
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$end = $start + strlen( $tag ); |
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$handle = $match[1][0]; |
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$css = $match[2][0]; |
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|
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$breaks_run = false; |
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|
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// A media query other than "all" changes when the CSS applies; it |
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// cannot be folded in with unconditional rules. |
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if ( preg_match( '#\bmedia=["\']([^"\']+)["\']#i', $tag, $media ) && 'all' !== strtolower( trim( $media[1] ) ) ) { |
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$breaks_run = true; |
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} |
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if ( in_array( $handle, $skip, true ) ) { |
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$breaks_run = true; |
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} |
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|
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$adjacent = ( null !== $prev_end && '' === trim( substr( $head, $prev_end, $start - $prev_end ) ) ); |
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|
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if ( $breaks_run ) { |
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if ( null !== $current ) { |
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$runs[] = $current; |
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$current = null; |
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} |
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$prev_end = $end; |
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continue; |
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} |
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|
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if ( null === $current || ! $adjacent ) { |
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if ( null !== $current ) { |
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$runs[] = $current; |
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} |
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$current = [ |
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'start' => $start, |
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'end' => $end, |
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'css' => $css, |
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]; |
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} else { |
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$current['end'] = $end; |
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$current['css'] .= "\n" . $css; |
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} |
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|
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$prev_end = $end; |
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}//end foreach |
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|
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if ( null !== $current ) { |
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$runs[] = $current; |
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} |
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|
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return $runs; |
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} |
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|
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/** |
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* Write CSS to a content-addressed file and return its URL. |
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* |
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* The name is a hash of the contents, so the file is immutable: changed CSS |
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* yields a different name rather than a stale file, and no invalidation |
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* hook is needed anywhere. |
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* |
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* @param string $css Stylesheet contents. |
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* @return string|null Public URL, or null on failure. |
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*/ |
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private function store_css( $css ) { |
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$hash = substr( sha1( $css ), 0, 20 ); |
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$dir = self::base_dir(); |
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$file = $dir . '/' . $hash . '.css'; |
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|
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if ( ! file_exists( $file ) ) { |
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if ( ! is_dir( $dir ) && ! wp_mkdir_p( $dir ) ) { |
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return null; |
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} |
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self::protect_dir(); |
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|
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// Written through the page-cache store so both features share one |
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// atomic write-then-rename implementation. |
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if ( ! \ABlocks\Classes\PageCache\Store::put_file( $file, $css ) ) { |
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return null; |
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} |
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} |
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|
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return self::base_url() . '/' . $hash . '.css'; |
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} |
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|
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/** |
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* Absolute path to the consolidated CSS directory. |
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* |
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* @return string |
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*/ |
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public static function base_dir() { |
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$upload = new FileUpload(); |
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return untrailingslashit( $upload->get_upload_dir() ) . '/' . self::DIR_NAME; |
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} |
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|
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/** |
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* Public URL of the consolidated CSS directory. |
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* |
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* @return string |
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*/ |
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public static function base_url() { |
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$upload = new FileUpload(); |
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return untrailingslashit( $upload->get_upload_url() ) . '/' . self::DIR_NAME; |
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} |
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|
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/** |
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* Drop an index.php guard so the directory cannot be browsed. |
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*/ |
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private static function protect_dir() { |
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$index = self::base_dir() . '/index.php'; |
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if ( ! file_exists( $index ) ) { |
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\ABlocks\Classes\PageCache\Store::put_file( $index, "<?php\n// Silence is golden.\n" ); |
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} |
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} |
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|
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/** |
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* Delete consolidated files untouched for longer than $days. |
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* |
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* Files are content-addressed and referenced by cached HTML, so they must |
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* never be purged alongside the page cache — doing so would leave cached |
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* pages pointing at stylesheets that no longer exist. Age-based collection |
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* is the safe way to reclaim space. |
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* |
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* @param int $days Age threshold. |
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* @return int Files removed. |
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*/ |
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public static function prune( $days = 30 ) { |
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$dir = self::base_dir(); |
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if ( ! is_dir( $dir ) ) { |
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return 0; |
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} |
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$cutoff = time() - ( max( 1, (int) $days ) * DAY_IN_SECONDS ); |
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$removed = 0; |
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// phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Return value is checked; a directory vanishing mid-sweep is normal. |
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$entries = @scandir( $dir ); |
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if ( false === $entries ) { |
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return 0; |
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} |
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foreach ( $entries as $entry ) { |
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if ( '.css' !== substr( $entry, -4 ) ) { |
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continue; |
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} |
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$path = $dir . '/' . $entry; |
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if ( filemtime( $path ) < $cutoff ) { |
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wp_delete_file( $path ); |
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$removed++; |
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} |
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} |
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return $removed; |
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} |
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} |
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|
