404-solution / includes / feedback / FeedbackEnvironmentExtras_CacheFingerprint.php

FeedbackEnvironmentExtras_CacheFingerprint.php in 404 Solution trunk, at includes/feedback/FeedbackEnvironmentExtras_CacheFingerprint.php

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1	<?php
2
3	if (!defined('ABSPATH')) {
4	exit;
5	}
6
7	/**
8	* Which cache implementation owns this site's request caches.
9	*
10	* Two questions with two different answers, and support reports need both.
11	* A drop-in file declares WHO INSTALLED the cache (`advanced-cache.php` and
12	* `object-cache.php` carry a `Plugin Name` header); the running constants,
13	* classes and extensions declare WHAT IS ACTUALLY RUNNING. They disagree more
14	* often than not on a site that has switched caching plugins without cleaning
15	* up, and that disagreement is itself the finding.
16	*
17	* Split from ABJ_404_Solution_FeedbackEnvironmentExtras_PlatformFingerprint,
18	* which answers a different question about a different subject: what the site
19	* is permanently sitting ON (host, panel, PHP execution stack). Cache
20	* ownership changes whenever an admin installs a plugin; hosting identity does
21	* not change for the life of the install, and the two marker vocabularies have
22	* nothing in common.
23	*
24	* No PII: only presence booleans, the declared plugin name from a drop-in
25	* header, and matched marker keys are returned. No file body and no path.
26	*
27	* Owned by ABJ_404_Solution_FeedbackEnvironmentExtras via composition; see that
28	* class's collect() method for the keyed probe registry that wraps each call
29	* below in recordProbe() for failure isolation.
30	*/
31	class ABJ_404_Solution_FeedbackEnvironmentExtras_CacheFingerprint {
32
33	/**
34	* How the presence of one object-cache backend is detected. A closed set,
35	* because the alternative -- a bare string beside two other bare strings --
36	* lets one typo silently switch a probe off. These values are also the
37	* `backend_detail` prefix, so they are part of what a support payload says.
38	*/
39	const MARKER_CONSTANT = 'const';
40	const MARKER_CLASS = 'class';
41	const MARKER_EXTENSION = 'ext';
42
43	/**
44	* The detector for each marker kind.
45	*
46	* A registry rather than three `if ($kind === ...)` branches: adding a
47	* fourth kind is then one entry that cannot be half-wired, and
48	* FeedbackEnvironmentExtras_CacheFingerprintTest asserts every kind used by
49	* probeObjectCacheBackend() has an entry here, so a marker whose kind has
50	* no detector fails a test instead of quietly never matching.
51	*
52	* @return array<string, callable(string): bool>
53	*/
54	private static function markerDetectors(): array {
55	return array(
56	self::MARKER_CONSTANT => static function (string $marker): bool {
57	return defined($marker);
58	},
59	// Autoloading is deliberately off: a support probe must observe what
60	// is already loaded, not cause a class to load as a side effect.
61	self::MARKER_CLASS => static function (string $marker): bool {
62	return class_exists($marker, false);
63	},
64	self::MARKER_EXTENSION => static function (string $marker): bool {
65	return extension_loaded($marker);
66	},
67	);
68	}
69
70	/**
71	* Report whether one of WordPress's two cache drop-ins is installed and
72	* the owner declared by its `Plugin Name` header. No file body, path, or
73	* other header is returned.
74	*
75	* The directory searched is WP_CONTENT_DIR (or ABSPATH/wp-content when
76	* that constant is absent), passed through the
77	* `abj404_cache_dropin_directory` filter so a site can point the probe
78	* somewhere else: installs that load their drop-ins from a relocated
79	* content directory, and anything that needs the probe scoped away from
80	* the live one, would otherwise be reported as having no cache drop-in at
81	* all. Same shape as `abj404_host_pressure_probe_paths` and
82	* `abj404_ajax_trace_directory`. A non-string or empty return leaves the
83	* computed default in force, so a misbehaving filter degrades to today's
84	* behaviour rather than probing '/'. Throwing is safe too: every probe
85	* runs inside FeedbackEnvironmentExtras::recordProbe(), which records the
86	* failure and substitutes the default.
87	*
88	* @param string $dropinKey One of `advanced_cache` or `object_cache`.
89	* @return array{present: bool, owner: string}
90	*/
91	public function probeCacheDropin(string $dropinKey): array {
92	$dropinFiles = array(
93	'advanced_cache' => 'advanced-cache.php',
94	'object_cache' => 'object-cache.php',
95	);
96	if (!isset($dropinFiles[$dropinKey])) {
97	return array('present' => false, 'owner' => '');
98	}
99
100	$contentDirectory = defined('WP_CONTENT_DIR')
101	? rtrim((string)WP_CONTENT_DIR, '/\\')
102	: rtrim((string)ABSPATH, '/\\') . '/wp-content';
103	if (function_exists('apply_filters')) {
104	$filtered = apply_filters('abj404_cache_dropin_directory', $contentDirectory, $dropinKey);
105	if (is_string($filtered) && trim($filtered) !== '') {
106	$contentDirectory = rtrim($filtered, '/\\');
107	}
108	}
109	$dropinPath = $contentDirectory . '/' . $dropinFiles[$dropinKey];
110	if (!is_file($dropinPath)) {
111	return array('present' => false, 'owner' => '');
112	}
113	if (!function_exists('get_file_data')) {
114	return array('present' => true, 'owner' => 'unknown');
115	}
116
117	$headers = get_file_data($dropinPath, array('owner' => 'Plugin Name'), 'plugin');
118	if (!is_array($headers) \|\| !isset($headers['owner']) \|\| !is_scalar($headers['owner'])) {
119	return array('present' => true, 'owner' => 'unknown');
120	}
121	$owner = trim(strip_tags((string)$headers['owner']));
122	$owner = preg_replace('/[[:cntrl:]]+/', ' ', $owner);
123	$owner = is_string($owner) ? trim($owner) : '';
124
125	return array(
126	'present' => true,
127	'owner' => $owner !== '' ? $owner : 'unknown',
128	);
129	}
130
131	/**
132	* Object-cache backend NAME. The base payload's `object_cache` enum
133	* answers "external or default"; this answers "external WHAT": Redis
134	* (predis vs phpredis vs Redis Object Cache plugin), Memcached,
135	* APCu, W3TC, LiteSpeed, WP Engine native, Pantheon, etc.
136	*
137	* @return array<string, mixed>
138	*/
139	public function probeObjectCacheBackend(): array {
140	$out = array(
141	'using_ext_cache' => false,
142	'backend' => 'unknown',
143	'backend_detail' => '',
144	);
145	if (function_exists('wp_using_ext_object_cache')) {
146	$out['using_ext_cache'] = (bool)wp_using_ext_object_cache();
147	}
148	// Known constants/classes/extensions from popular object-cache
149	// drop-ins. The first match wins, so a Redis Object Cache Pro install
150	// is not also tagged as plain Redis.
151	//
152	// Keyed rather than a (name, kind, marker) tuple, and the kind is one
153	// of the MARKER_* constants rather than a bare string, because a
154	// mistyped kind used to fail OPEN: no branch matched, the check simply
155	// never ran, and the probe reported "no object cache" for a host that
156	// has one. A detector that silently stops detecting is worse than one
157	// that reports nothing, since the answer still looks like an answer.
158	$checks = array(
159	array('backend' => 'redis_object_cache_pro', 'kind' => self::MARKER_CONSTANT, 'marker' => 'WP_REDIS_VERSION'),
160	array('backend' => 'redis_object_cache_pro', 'kind' => self::MARKER_CLASS, 'marker' => 'RedisCachePro\\Plugin'),
161	array('backend' => 'redis_object_cache', 'kind' => self::MARKER_CLASS, 'marker' => 'WP_Object_Cache'),
162	array('backend' => 'memcached', 'kind' => self::MARKER_CLASS, 'marker' => 'Memcached'),
163	array('backend' => 'apcu', 'kind' => self::MARKER_EXTENSION, 'marker' => 'apcu'),
164	array('backend' => 'w3_total_cache', 'kind' => self::MARKER_CONSTANT, 'marker' => 'W3TC_VERSION'),
165	array('backend' => 'litespeed_cache', 'kind' => self::MARKER_CONSTANT, 'marker' => 'LSCWP_DIR'),
166	array('backend' => 'wp_engine_native', 'kind' => self::MARKER_CONSTANT, 'marker' => 'WPE_APIKEY'),
167	array('backend' => 'pantheon', 'kind' => self::MARKER_CONSTANT, 'marker' => 'PANTHEON_ENVIRONMENT'),
168	);
169	$detectors = self::markerDetectors();
170	foreach ($checks as $check) {
171	$detector = $detectors[$check['kind']];
172	if ($detector($check['marker'])) {
173	$out['backend'] = $check['backend'];
174	$out['backend_detail'] = $check['kind'] . ':' . $check['marker'];
175	return $out;
176	}
177	}
178	// Default WP object cache used in-memory per request.
179	if (!$out['using_ext_cache']) {
180	$out['backend'] = 'default';
181	$out['backend_detail'] = 'wp_object_cache:in_memory';
182	}
183	return $out;
184	}
185	}
186