ablocks / includes / performance / page-cache.php

page-cache.php in aBlocks – Gutenberg Blocks, User Dashboard Builder, Popup Builder, Form Builder & Animation Builder trunk, at includes/performance/page-cache.php

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1	<?php
2	namespace ABlocks\Performance;
3
4	if ( ! defined( 'ABSPATH' ) ) {
5	exit;
6	}
7
8	use ABlocks\Classes\PageCache\Rules;
9	use ABlocks\Classes\PageCache\Store;
10
11	/**
12	* Performance Suite — full-page HTML cache (write path).
13	*
14	* Captures the rendered page and stores it on disk so later requests can be
15	* served without re-running WordPress, block parsing and theme rendering.
16	*
17	* This class owns the write side only. Serving happens far earlier in the
18	* request than any plugin class is loaded — see the serve hook registered from
19	* ablocks.php, the advanced-cache.php drop-in, and the nginx rule. All of them
20	* defer to {@see Rules} so every tier makes the same decision.
21	*
22	* Opt-in via `perf_page_cache` (default off). See docs/PAGE-CACHE-PLAN.md.
23	*/
24	class PageCache {
25
26	/**
27	* Marker appended to cached copies, so `curl` shows whether a response came
28	* from disk and when it was generated. Never present in the live response.
29	*/
30	const META_PREFIX = '<!-- ablocks-page-cache ';
31
32	public static function init() {
33	// Registered before the gates below: `purge` must stay available so a
34	// site owner can clear files left behind after switching the feature off.
35	if ( defined( 'WP_CLI' ) && \WP_CLI ) {
36	\ABlocks\Classes\PageCache\Cli::register();
37	}
38
39	// Maintenance is registered before the frontend gates below: pruning has
40	// to keep running in admin and cron contexts, which is where WP-Cron
41	// actually fires.
42	\ABlocks\Classes\PageCache\Scheduler::init();
43
44	// Also before the frontend gates: the toolbar has to appear both on the
45	// site and in wp-admin, and its action handler runs on admin-post.php.
46	\ABlocks\Classes\PageCache\AdminBar::init();
47
48	if ( is_admin() ) {
49	return;
50	}
51	if ( ! Rules::is_enabled() ) {
52	return;
53	}
54
55	$self = new self();
56
57	// Priority 0 on template_redirect: the earliest point at which the main
58	// query has run (so is_404()/is_search() are meaningful) while still
59	// being ahead of anything that renders. Starting first also makes this
60	// the outermost output buffer, and nested buffers flush inner-first —
61	// so the callback receives output after other plugins have transformed
62	// it, which is what we want to store.
63	add_action( 'template_redirect', [ $self, 'start_buffer' ], 0 );
64	}
65
66	/**
67	* Begin capturing output, unless the request is disqualified up front.
68	*/
69	public function start_buffer() {
70	// Cheap superglobal-only gate. The expensive, WordPress-aware checks run
71	// at write time, when the response is actually known.
72	if ( Rules::should_bypass_request() ) {
73	$this->debug_header( 'bypass', Rules::last_reason() );
74	return;
75	}
76
77	ob_start( [ $this, 'maybe_cache' ] );
78	}
79
80	/**
81	* Output-buffer callback: decide, write, and always return the buffer intact.
82	*
83	* This runs during shutdown. It must never throw and must never alter the
84	* response — a caching layer that can break the page it is caching is worse
85	* than no caching layer.
86	*
87	* @param string $buffer Rendered output.
88	* @return string The same buffer, unmodified.
89	*/
90	public function maybe_cache( $buffer ) {
91	if ( ! is_string( $buffer ) \|\| '' === $buffer ) {
92	return $buffer;
93	}
94
95	try {
96	$reason = Rules::response_bypass_reason();
97	if ( null === $reason ) {
98	$reason = Rules::body_bypass_reason( $buffer );
99	}
100
101	if ( null !== $reason ) {
102	$this->debug_header( 'bypass', $reason );
103	return $buffer;
104	}
105
106	$file = Store::current_file_path();
107	if ( null === $file ) {
108	$this->debug_header( 'bypass', 'unrepresentable-path' );
109	return $buffer;
110	}
111
112	$gzip = (bool) \ABlocks\Helper::get_settings( 'perf_page_cache_gzip', true );
113	$written = Store::write( $file, $buffer . $this->meta_comment(), $gzip );
114
115	$this->debug_header( $written ? 'store' : 'bypass', $written ? null : 'write-failed' );
116	} catch ( \Throwable $e ) {
117	// Any failure here is a caching failure, not a page failure. Swallow
118	// it, note it when debugging, and serve the page as normal.
119	$this->debug_header( 'bypass', 'exception' );
120	if ( defined( 'WP_DEBUG' ) && WP_DEBUG ) {
121	error_log( 'aBlocks page cache: ' . $e->getMessage() ); // phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log
122	}
123	}//end try
124
125	return $buffer;
126	}
127
128	/**
129	* Trailing marker stored with the cached copy.
130	*
131	* Kept inside an HTML comment rather than a sidecar file: no extra inode per
132	* page, harmless when nginx serves the file directly, and it makes a cache
133	* hit self-identifying when someone curls the URL.
134	*
135	* @return string
136	*/
137	private function meta_comment() {
138	$meta = [
139	'url' => home_url( Rules::request_path() ),
140	'created' => gmdate( 'c' ),
141	'version' => ABLOCKS_VERSION,
142	];
143
144	$json = wp_json_encode( $meta );
145	if ( false === $json ) {
146	return '';
147	}
148
149	// Defensive: a comment body containing "--" or ">" would break out of the
150	// comment. None of the values above can, but the URL is request-derived.
151	$json = str_replace( [ '--', '>' ], [ '- -', '' ], $json );
152
153	return "\n" . self::META_PREFIX . $json . " -->\n";
154	}
155
156	/**
157	* Emit a diagnostic header while debugging.
158	*
159	* Only under WP_DEBUG: the reason string names cookie prefixes and query
160	* behaviour, which is useful to a developer and needless surface on a
161	* production response.
162	*
163	* @param string $state 'store' or 'bypass'.
164	* @param string\|null $reason Bypass reason, when applicable.
165	*/
166	private function debug_header( $state, $reason = null ) {
167	if ( ! defined( 'WP_DEBUG' ) \|\| ! WP_DEBUG ) {
168	return;
169	}
170	if ( headers_sent() ) {
171	return;
172	}
173	$value = $state . ( $reason ? '; ' . $reason : '' );
174	header( 'X-ABlocks-Cache: ' . $value );
175	}
176	}
177