← All changes | includes/class-object-cache.php +1381 -17 1.0.2 → 1.4.0 View file →

		@@ -36,21 +36,39 @@
36	36	* Inspect the runtime + filesystem for a persistent object cache.
37	37	*
38	38	* @return array{
39	39	* drop_in_installed: bool,
	40	+ * drop_in_is_ours: bool, // installed AND carries our tag
40	41	* drop_in_path: string,
41	42	* drop_in_label: string,
42	43	* backend: string, // redis|memcached|apcu|wp_default|unknown
43	44	* wp_cache_active: bool, // wp_using_ext_object_cache
	45	+ * degraded: bool, // ours is installed but NOT persisting
	46	+ * persistent: bool, // ours is installed AND persisting
44	47	* class_available: array<string,bool>
45	48	* }
46	49	*/
47		- public static function detect(): array {
	50	+ public static function detect( bool $with_owner = false ): array {
48	51	$dropin = defined( 'WP_CONTENT_DIR' ) ? WP_CONTENT_DIR . '/object-cache.php' : '';
49	52	$has_drop_in = '' !== $dropin && file_exists( $dropin );
50	53	$label = $has_drop_in ? self::sniff_drop_in_label( $dropin ) : '';
51	54	$ext_in_use = function_exists( 'wp_using_ext_object_cache' ) ? (bool) wp_using_ext_object_cache() : false;
52	55
	56	+ // When OUR drop-in is the live one it exposes whether it actually
	57	+ // connected a persistent backend. A drop-in that's installed but
	58	+ // degraded reports wp_using_ext_object_cache()=true yet persists
	59	+ // nothing — the silent failure that makes a site slow. Read the honest
	60	+ // state straight off the running instance. (FBS-82210)
	61	+ $degraded = false;
	62	+ $persistent = false;
	63	+ if ( $has_drop_in && isset( $GLOBALS['wp_object_cache'] ) && is_object( $GLOBALS['wp_object_cache'] ) ) {
	64	+ $oc = $GLOBALS['wp_object_cache'];
	65	+ if ( method_exists( $oc, 'is_persistent' ) ) {
	66	+ $persistent = (bool) $oc->is_persistent();
	67	+ $degraded = ! $persistent;
	68	+ }
	69	+ }
	70	+
53	71	// Class sniffer — independent of any plugin. Tells us what's
54	72	// available to actually use, separate from what's wired up.
55	73	$class_available = array(
56	74	'Redis' => class_exists( '\\Redis' ),
		@@ -62,30 +80,125 @@
62	80	$backend = 'unknown';
63	81	if ( ! $ext_in_use ) {
64	82	$backend = 'wp_default';
65	83	} elseif ( $has_drop_in ) {
66		- // Best-effort: the label usually contains the backend name.
67		- $lc = strtolower( $label );
68		- if ( false !== strpos( $lc, 'redis' ) ) {
69		- $backend = 'redis';
70		- } elseif ( false !== strpos( $lc, 'memcached' ) || false !== strpos( $lc, 'memcache' ) ) {
71		- $backend = 'memcached';
72		- } elseif ( false !== strpos( $lc, 'apcu' ) ) {
73		- $backend = 'apcu';
	84	+ // Authoritative source first: our own drop-in records the chosen
	85	+ // backend in the XSPEED_OC_BACKEND constant (written to wp-config
	86	+ // on enable). The drop-in label is the generic
	87	+ // "XSPEED_OBJECT_CACHE_DROPIN" and does NOT contain the backend
	88	+ // name, so the label sniff below would always yield "unknown" for
	89	+ // our drop-in — read the constant instead. (FBS-82111)
	90	+ if ( defined( 'XSPEED_OC_BACKEND' ) && '' !== (string) constant( 'XSPEED_OC_BACKEND' ) ) {
	91	+ $backend = strtolower( (string) constant( 'XSPEED_OC_BACKEND' ) );
	92	+ } else {
	93	+ // Foreign drop-in (W3TC / Redis Object Cache / …): best-effort
	94	+ // guess from the label, which usually names the backend.
	95	+ $lc = strtolower( $label );
	96	+ if ( false !== strpos( $lc, 'redis' ) ) {
	97	+ $backend = 'redis';
	98	+ } elseif ( false !== strpos( $lc, 'memcached' ) || false !== strpos( $lc, 'memcache' ) ) {
	99	+ $backend = 'memcached';
	100	+ } elseif ( false !== strpos( $lc, 'apcu' ) ) {
	101	+ $backend = 'apcu';
	102	+ }
74	103	}
75	104	}
76	105
77	106	return array(
78	107	'drop_in_installed' => $has_drop_in,
	108	+ // Whether the installed drop-in is OURS. A foreign one (W3TC,
	109	+ // Redis Object Cache, LiteSpeed) means the object cache belongs to
	110	+ // another plugin: we must not offer to configure or disable it,
	111	+ // and "installed" must not be read as "xSpeed is running".
	112	+ 'drop_in_is_ours' => $has_drop_in && self::is_our_dropin_present(),
79	113	'drop_in_path' => $dropin,
80	114	'drop_in_label' => $label,
81	115	'backend' => $backend,
82	116	'wp_cache_active' => $ext_in_use,
	117	+ 'degraded' => $degraded,
	118	+ 'persistent' => $persistent,
83	119	'class_available' => $class_available,
	120	+ // Who owns a foreign drop-in and how a switch would go, so every
	121	+ // surface can offer it (or say why not) the same way. (#686)
	122	+ // Only on request: it reads plugin folders, and module status
	123	+ // calls detect() on dashboard loads.
	124	+ 'owner' => $with_owner && $has_drop_in && ! self::is_our_dropin_present() ? Object_Cache_Takeover::owner() : null,
	125	+ // The plugin a switch replaced, which Disable can put back.
	126	+ 'previous_owner' => self::previous_owner(),
84	127	);
85	128	}
86	129
87	130	/**
	131	+ * Label of the plugin xSpeed switched from, while ours is installed.
	132	+ *
	133	+ * @return array{label:string}|null
	134	+ */
	135	+ private static function previous_owner(): ?array {
	136	+ if ( ! self::is_our_dropin_present() ) {
	137	+ return null;
	138	+ }
	139	+ $record = Object_Cache_Takeover::record();
	140	+ return null === $record ? null : array( 'label' => $record['label'] );
	141	+ }
	142	+
	143	+ /** A drop-in that is not ours sits in wp-content. */
	144	+ private static function foreign_dropin_present(): bool {
	145	+ $dropin = defined( 'WP_CONTENT_DIR' ) ? WP_CONTENT_DIR . '/object-cache.php' : '';
	146	+ return '' !== $dropin && ( file_exists( $dropin ) || is_link( $dropin ) ) && ! self::is_our_dropin_present();
	147	+ }
	148	+
	149	+ /** Our drop-in is the object cache this request is running on. */
	150	+ private static function our_dropin_is_live(): bool {
	151	+ return isset( $GLOBALS['wp_object_cache'] ) && $GLOBALS['wp_object_cache'] instanceof \XSpeed_Object_Cache;
	152	+ }
	153	+
	154	+ /**
	155	+ * Delete this site's keys from Redis, the same `salt:*` scope the
	156	+ * drop-in's flush uses. For when the drop-in is not loaded in this
	157	+ * request, so wp_cache_flush() would flush someone else's cache or none.
	158	+ * Memcached has no key enumeration; its namespace generation covers it.
	159	+ *
	160	+ * @param array $opts Settings array.
	161	+ * @return int Keys deleted, or -1 when nothing could be done.
	162	+ */
	163	+ public static function purge_namespace( array $opts ): int {
	164	+ if ( 'redis' !== (string) ( $opts['backend'] ?? 'redis' ) ) {
	165	+ return -1;
	166	+ }
	167	+ $salt = self::effective_salt( $opts );
	168	+ if ( '' === $salt ) {
	169	+ return -1;
	170	+ }
	171	+ $client = new Redis_Client(
	172	+ self::str( $opts, 'redis_host', '127.0.0.1' ),
	173	+ self::int( $opts, 'redis_port', 6379 ),
	174	+ (float) self::int( $opts, 'connection_timeout', 1 ),
	175	+ false
	176	+ );
	177	+ if ( ! $client->connect() ) {
	178	+ return -1;
	179	+ }
	180	+ $user = self::str( $opts, 'redis_user', '' );
	181	+ $pass = self::str( $opts, 'redis_password', '' );
	182	+ if ( ( '' !== $pass || '' !== $user ) && false === $client->auth( $pass, $user ) ) {
	183	+ $client->close();
	184	+ return -1;
	185	+ }
	186	+ $db = self::int( $opts, 'redis_database', 0 );
	187	+ if ( $db > 0 ) {
	188	+ $client->select( $db );
	189	+ }
	190	+ $pattern = str_replace(
	191	+ array( '\\', '*', '?', '[', ']' ),
	192	+ array( '\\\\', '\\*', '\\?', '\\[', '\\]' ),
	193	+ $salt
	194	+ ) . ':*';
	195	+ $deleted = $client->delete_by_pattern( $pattern );
	196	+ $client->close();
	197	+ return $deleted;
	198	+ }
	199	+
	200	+ /**
88	201	* Flush whatever cache backend is wired up. Works against any
89	202	* compliant drop-in OR the WP default in-memory cache.
90	203	*/
91	204	public static function flush(): bool {
		@@ -108,39 +221,1290 @@
108	221
109	222	if ( 'redis' === $backend ) {
110	223	$host = self::str( $opts, 'redis_host', '127.0.0.1' );
111	224	$port = self::int( $opts, 'redis_port', 6379 );
	225	+ $user = self::str( $opts, 'redis_user', '' );
112	226	$pass = self::str( $opts, 'redis_password', '' );
113	227	$db = self::int( $opts, 'redis_database', 0 );
114		- $prefix = self::str( $opts, 'key_prefix', '' );
	228	+ $prefix = self::effective_salt( $opts );
115	229	$timeout = self::int( $opts, 'connection_timeout', 1 );
116	230	$persist = ! empty( $opts['persistent'] );
117	231
118	232	$lines[] = "define( 'WP_REDIS_HOST', '" . self::esc( $host ) . "' );";
119	233	$lines[] = "define( 'WP_REDIS_PORT', " . $port . ' );';
	234	+ // Emit the ACL username only when set (Redis 6+). The drop-in
	235	+ // reads it; an empty user keeps the legacy default-user behavior.
	236	+ if ( '' !== $user ) {
	237	+ $lines[] = "define( 'WP_REDIS_USER', '" . self::esc( $user ) . "' );";
	238	+ }
120	239	if ( '' !== $pass ) {
121	240	$lines[] = "define( 'WP_REDIS_PASSWORD', '" . self::esc( $pass ) . "' );";
122	241	}
123	242	$lines[] = "define( 'WP_REDIS_DATABASE', " . $db . ' );';
124		- if ( '' !== $prefix ) {
125		- $lines[] = "define( 'WP_CACHE_KEY_SALT', '" . self::esc( $prefix ) . "' );";
126		- }
	243	+ $lines[] = "define( 'WP_CACHE_KEY_SALT', '" . self::esc( $prefix ) . "' );";
127	244	$lines[] = "define( 'WP_REDIS_TIMEOUT', " . $timeout . ' );';
128	245	$lines[] = "define( 'WP_REDIS_PERSISTENT', " . ( $persist ? 'true' : 'false' ) . ' );';
129	246	} elseif ( 'memcached' === $backend ) {
130	247	$host = self::str( $opts, 'memcached_host', '127.0.0.1' );
131	248	$port = self::int( $opts, 'memcached_port', 11211 );
132		- $prefix = self::str( $opts, 'key_prefix', '' );
	249	+ $prefix = self::effective_salt( $opts );
133	250	$lines[] = "global \$memcached_servers;";
134	251	$lines[] = "\$memcached_servers = array( array( '" . self::esc( $host ) . "', " . $port . ' ) );';
135		- if ( '' !== $prefix ) {
136		- $lines[] = "define( 'WP_CACHE_KEY_SALT', '" . self::esc( $prefix ) . "' );";
	252	+ $lines[] = "define( 'WP_CACHE_KEY_SALT', '" . self::esc( $prefix ) . "' );";
	253	+ } else {
	254	+ $lines[] = '// No snippet for backend: ' . $backend;
	255	+ }
	256	+
	257	+ return implode( "\n", $lines ) . "\n";
	258	+ }
	259	+
	260	+ /**
	261	+ * Identifier embedded in our drop-in so we can recognise (and safely
	262	+ * overwrite / remove) only files we installed.
	263	+ */
	264	+ private const DROPIN_TAG = 'XSPEED_OBJECT_CACHE_DROPIN';
	265	+
	266	+ /** Markers wrapping the constants we write into wp-config.php. */
	267	+ private const CONFIG_BEGIN = '/* BEGIN xSpeed Object Cache */';
	268	+ private const CONFIG_END = '/* END xSpeed Object Cache */';
	269	+
	270	+ /**
	271	+ * True when wp-content/object-cache.php exists AND is ours (carries the
	272	+ * drop-in tag). Lets callers decide whether a re-sync applies without
	273	+ * exposing the tag itself.
	274	+ */
	275	+ public static function is_our_dropin_present(): bool {
	276	+ $target = WP_CONTENT_DIR . '/object-cache.php';
	277	+ if ( ! file_exists( $target ) ) {
	278	+ return false;
	279	+ }
	280	+ $contents = file_get_contents( $target ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- read-only ours-check; WP_Filesystem may not be initialized this early.
	281	+ return is_string( $contents ) && false !== strpos( $contents, self::DROPIN_TAG );
	282	+ }
	283	+
	284	+ /**
	285	+ * Live connection test against the configured backend. Never throws;
	286	+ * returns a structured pass/fail the UI can show before we write anything.
	287	+ *
	288	+ * @param array $opts Settings array (backend, redis_host, ...).
	289	+ * @return array{ok:bool,backend:string,message:string,latency_ms:?float}
	290	+ */
	291	+ public static function test_connection( array $opts ): array {
	292	+ $backend = (string) ( $opts['backend'] ?? 'redis' );
	293	+ $start = microtime( true );
	294	+
	295	+ try {
	296	+ if ( 'memcached' === $backend ) {
	297	+ $host = self::str( $opts, 'memcached_host', '127.0.0.1' );
	298	+ $port = self::int( $opts, 'memcached_port', 11211 );
	299	+ $timeout = self::int( $opts, 'connection_timeout', 1 );
	300	+
	301	+ // Prefer the ext/memcached extension (libmemcached).
	302	+ if ( class_exists( '\\Memcached' ) ) {
	303	+ $mc = new \Memcached();
	304	+ $mc->addServer( $host, $port );
	305	+ $stats = @$mc->getStats();
	306	+ $ok = is_array( $stats ) && ! empty( array_filter( $stats ) );
	307	+ return self::test_result(
	308	+ $ok,
	309	+ $backend,
	310	+ $ok ? "Connected to Memcached at {$host}:{$port} (ext/memcached)." : "Could not reach Memcached at {$host}:{$port}.",
	311	+ $start
	312	+ );
	313	+ }
	314	+
	315	+ // Pure-PHP fallback — our own client, zero dependencies.
	316	+ $mc = new Memcached_Client( $host, $port, (float) $timeout );
	317	+ if ( ! $mc->connect() ) {
	318	+ return self::test_result( false, $backend, "Could not connect to Memcached at {$host}:{$port}." );
	319	+ }
	320	+ $ver = $mc->version();
	321	+ $mc->close();
	322	+ $ok = ( false !== $ver );
	323	+ return self::test_result(
	324	+ $ok,
	325	+ $backend,
	326	+ $ok ? "Connected to Memcached at {$host}:{$port} (built-in client)." : "Memcached at {$host}:{$port} did not respond.",
	327	+ $start
	328	+ );
137	329	}
	330	+
	331	+ // Redis. Prefer the phpredis extension (faster C client); fall back
	332	+ // to xSpeed's own dependency-free Redis_Client (pure-PHP RESP over a
	333	+ // socket) so Redis works even without the extension — true
	334	+ // plug-and-play, no bundled library.
	335	+ $host = self::str( $opts, 'redis_host', '127.0.0.1' );
	336	+ $port = self::int( $opts, 'redis_port', 6379 );
	337	+ $timeout = self::int( $opts, 'connection_timeout', 1 );
	338	+ $user = self::str( $opts, 'redis_user', '' );
	339	+ $pass = self::str( $opts, 'redis_password', '' );
	340	+ $db = self::int( $opts, 'redis_database', 0 );
	341	+
	342	+ if ( class_exists( '\\Redis' ) ) {
	343	+ $redis = new \Redis();
	344	+ if ( ! @$redis->connect( $host, $port, $timeout ) ) {
	345	+ return self::test_result( false, $backend, "Could not connect to Redis at {$host}:{$port}." );
	346	+ }
	347	+ // Redis 6+ ACL: when a username is set, authenticate as that user
	348	+ // (phpredis ≥ 5.3 accepts ['user'=>..,'pass'=>..]); otherwise keep
	349	+ // the legacy password-only form that authenticates as `default`.
	350	+ $auth_ok = self::phpredis_auth( $redis, $user, $pass );
	351	+ if ( null !== $auth_ok && ! $auth_ok ) {
	352	+ return self::test_result( false, $backend, '' !== $user ? 'Redis authentication failed — check the Redis user + password (ACL).' : 'Redis authentication failed — check the password.' );
	353	+ }
	354	+ if ( $db > 0 && ! @$redis->select( $db ) ) {
	355	+ return self::test_result( false, $backend, "Could not select Redis database {$db}." );
	356	+ }
	357	+ $pong = @$redis->ping();
	358	+ $ok = ( '+PONG' === $pong || true === $pong || 'PONG' === $pong );
	359	+ if ( ! $ok ) {
	360	+ return self::test_result( false, $backend, "Redis at {$host}:{$port} did not respond to PING.", $start );
	361	+ }
	362	+ // Write-verification: PING only proves auth, not that the user can
	363	+ // STORE data. ACL-namespaced hosts (xCloud) restrict a user to a
	364	+ // key pattern (~redis:<id>:*); a SET outside it is NOPERM-denied and
	365	+ // the drop-in's @$redis->set() swallows it — enable() would then
	366	+ // green-light a cache that silently persists nothing. Do a real
	367	+ // SET/GET/DEL round-trip on a probe key built with the user's key
	368	+ // prefix so a namespace restriction is caught here. (FBS-83118 OC-2)
	369	+ $probe = self::probe_key( $opts );
	370	+ $set = @$redis->set( $probe, '1', 5 ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- NOPERM/denied is the negative answer we report, not a fatal.
	371	+ $got = @$redis->get( $probe ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- same.
	372	+ @$redis->del( $probe ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- best-effort cleanup.
	373	+ if ( ! $set || '1' !== (string) $got ) {
	374	+ return self::test_result( false, $backend, self::write_denied_message( $opts, $host, $port ), $start );
	375	+ }
	376	+ return self::test_result( true, $backend, self::with_prefix_advisory( "Connected to Redis at {$host}:{$port} (phpredis).", $opts ), $start );
	377	+ }
	378	+
	379	+ // Pure-PHP fallback — our own client, zero dependencies.
	380	+ $rc = new Redis_Client( $host, $port, (float) $timeout, false );
	381	+ if ( ! $rc->connect() ) {
	382	+ return self::test_result( false, $backend, "Could not connect to Redis at {$host}:{$port}." );
	383	+ }
	384	+ // Authenticate when a user OR a password is set. Gating on password
	385	+ // alone skipped auth for the "ACL user + empty password" case, which
	386	+ // then failed later at PING with a misleading message. (FBS-83118 OC-1)
	387	+ if ( ( '' !== $pass || '' !== $user ) && false === $rc->auth( $pass, $user ) ) {
	388	+ $rc->close();
	389	+ return self::test_result( false, $backend, '' !== $user ? 'Redis authentication failed — check the Redis user + password (ACL).' : 'Redis authentication failed — check the password.' );
	390	+ }
	391	+ if ( $db > 0 ) {
	392	+ $rc->select( $db );
	393	+ }
	394	+ $pong = $rc->ping();
	395	+ $ok = ( is_string( $pong ) && false !== stripos( $pong, 'PONG' ) );
	396	+ if ( ! $ok ) {
	397	+ $rc->close();
	398	+ return self::test_result( false, $backend, "Redis at {$host}:{$port} did not respond to PING.", $start );
	399	+ }
	400	+ // Write-verification round-trip — same rationale as the phpredis path
	401	+ // above. (FBS-83118 OC-2)
	402	+ $probe = self::probe_key( $opts );
	403	+ $set = $rc->set( $probe, '1' );
	404	+ $got = $rc->get( $probe );
	405	+ $rc->del( $probe );
	406	+ $rc->close();
	407	+ if ( ! $set || '1' !== (string) $got ) {
	408	+ return self::test_result( false, $backend, self::write_denied_message( $opts, $host, $port ), $start );
	409	+ }
	410	+ return self::test_result( true, $backend, self::with_prefix_advisory( "Connected to Redis at {$host}:{$port} (built-in client).", $opts ), $start );
	411	+ } catch ( \Throwable $e ) {
	412	+ return self::test_result( false, $backend, 'Connection error: ' . $e->getMessage() );
	413	+ }
	414	+ }
	415	+
	416	+ /**
	417	+ * Redis glob metacharacters that must never appear unescaped in a SCAN
	418	+ * MATCH pattern. `\` is the escape character itself.
	419	+ */
	420	+ private const GLOB_METACHARS = '*?[]\\';
	421	+
	422	+ /**
	423	+ * Whether a salt contains Redis glob metacharacters.
	424	+ *
	425	+ * The salt is interpolated into the drop-in's scoped-flush patterns. The
	426	+ * drop-in escapes it, so caching and purging are correct either way — but
	427	+ * an explicit Cache Key Prefix exists to match a host's ACL namespace
	428	+ * byte-for-byte, and a wildcard in it is almost always a typo rather than
	429	+ * a real namespace. Reporting it on Test connection is the one place the
	430	+ * user is already looking at their prefix.
	431	+ *
	432	+ * @param string $salt Effective salt.
	433	+ * @return bool
	434	+ */
	435	+ public static function salt_has_glob_metachars( string $salt ): bool {
	436	+ return strcspn( $salt, self::GLOB_METACHARS ) !== strlen( $salt );
	437	+ }
	438	+
	439	+ /**
	440	+ * Append a prefix advisory to an otherwise-successful connection message.
	441	+ *
	442	+ * @param string $message Success message.
	443	+ * @param array $opts Settings array.
	444	+ * @return string
	445	+ */
	446	+ private static function with_prefix_advisory( string $message, array $opts ): string {
	447	+ // Deliberately the TYPED prefix, not effective_salt(): this advisory
	448	+ // says "the field you are looking at probably has a typo in it". A
	449	+ // host-pinned WP_CACHE_KEY_SALT is not editable from this screen and
	450	+ // purges are correctly scoped regardless (the drop-in escapes it), so
	451	+ // warning about a host's own namespace would be noise on every ACL
	452	+ // host. A derived salt is glob-free by construction.
	453	+ $prefix = self::str( $opts, 'key_prefix', '' );
	454	+ if ( '' === $prefix || ! self::salt_has_glob_metachars( $prefix ) ) {
	455	+ return $message;
	456	+ }
	457	+ return $message . ' Note: the Cache key prefix contains one of * ? [ ] \\.'
	458	+ . ' Purges stay scoped to this site, but these are wildcard characters'
	459	+ . ' in Redis — check the prefix matches your host\'s key exactly.';
	460	+ }
	461	+
	462	+ private static function test_result( bool $ok, string $backend, string $message, ?float $start = null ): array {
	463	+ return array(
	464	+ 'ok' => $ok,
	465	+ 'backend' => $backend,
	466	+ 'message' => $message,
	467	+ 'latency_ms' => $start ? round( ( microtime( true ) - $start ) * 1000, 2 ) : null,
	468	+ );
	469	+ }
	470	+
	471	+ /**
	472	+ * Authenticate a phpredis connection, honoring Redis 6+ ACL usernames.
	473	+ *
	474	+ * Returns null when no auth is needed (empty username AND password) so
	475	+ * callers can distinguish "didn't try" from "tried and failed". When a
	476	+ * username is present we pass ['user'=>..,'pass'=>..] which phpredis
	477	+ * ≥ 5.3 maps to the two-argument AUTH; otherwise the legacy
	478	+ * password-only form authenticates as the built-in `default` user.
	479	+ *
	480	+ * @param \Redis $redis Connected phpredis instance.
	481	+ * @param string $user ACL username; '' = default user.
	482	+ * @param string $pass Password.
	483	+ * @return bool|null true/false on auth attempt, null if none needed.
	484	+ */
	485	+ private static function phpredis_auth( $redis, string $user, string $pass ) {
	486	+ if ( '' === $user && '' === $pass ) {
	487	+ return null;
	488	+ }
	489	+ try {
	490	+ if ( '' !== $user ) {
	491	+ return (bool) @$redis->auth( array( 'user' => $user, 'pass' => $pass ) ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- phpredis throws on bad auth; we report it as a failed test, not a fatal.
	492	+ }
	493	+ return (bool) @$redis->auth( $pass ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- same.
	494	+ } catch ( \Throwable $e ) {
	495	+ return false;
	496	+ }
	497	+ }
	498	+
	499	+ /**
	500	+ * Resolve the salt that namespaces this site's cache keys.
	501	+ *
	502	+ * An explicit Cache Key Prefix always wins — on ACL/namespaced hosts
	503	+ * (xCloud) it MUST match the host's "Redis Object Cache Key" or writes are
	504	+ * denied (NOPERM), so we never override what the user typed.
	505	+ *
	506	+ * When the field is blank we derive a stable, per-site salt instead of
	507	+ * falling back to an empty one. An empty salt makes every key look like
	508	+ * `:{prefix}:{group}:{key}` — identical on every install — so two sites
	509	+ * sharing one Redis/Memcached server collide. That is not a theoretical
	510	+ * clash: `blog-details` / `blog-lookup` are how WordPress resolves which
	511	+ * site a request belongs to, so the second site reads the first site's
	512	+ * entries and redirects to it.
	513	+ *
	514	+ * The derived value is a hash of the site URL plus the DB name/prefix, so
	515	+ * it is unique per install, stable across requests (no cache churn), and
	516	+ * safe to embed in wp-config.php.
	517	+ *
	518	+ * @param array $opts Settings array.
	519	+ * @return string Non-empty salt.
	520	+ */
	521	+ public static function effective_salt( array $opts ): string {
	522	+ $prefix = self::str( $opts, 'key_prefix', '' );
	523	+ if ( '' !== $prefix ) {
	524	+ return $prefix;
	525	+ }
	526	+
	527	+ // A salt WE already wrote is authoritative over a fresh derivation.
	528	+ // The keys in the backend are named after it, so re-deriving a
	529	+ // different value would orphan every one of them — a needless
	530	+ // cache-cooling on an install that is already correctly namespaced.
	531	+ // This matters because derive_salt()'s rule was corrected (see there):
	532	+ // without this branch, the next wp-config sync would rewrite the block
	533	+ // with a new salt and throw away a warm cache on every existing site.
	534	+ if ( defined( 'XSPEED_OC_SALT' ) && '' !== (string) constant( 'XSPEED_OC_SALT' ) ) {
	535	+ return (string) constant( 'XSPEED_OC_SALT' );
	536	+ }
	537	+
	538	+ // A salt the HOST pinned in its own wp-config (outside our block) is
	539	+ // the next authority. On ACL/namespaced Redis the host grants write
	540	+ // access to that namespace and no other, so replacing it with a
	541	+ // derived value gets every write denied (NOPERM) and the site silently
	542	+ // stops caching.
	543	+ // WP_REDIS_PREFIX is checked alongside WP_CACHE_KEY_SALT and before it,
	544	+ // matching the order the schema and the drop-in resolve (#398). It is
	545	+ // the name Redis Object Cache uses and the one managed hosts actually
	546	+ // write, so honouring only the older alias left the commonest
	547	+ // ACL-namespaced case deriving a salt the host denies writes to.
	548	+ foreach ( array( 'WP_REDIS_PREFIX', 'WP_CACHE_KEY_SALT' ) as $name ) {
	549	+ if ( defined( $name ) && '' !== (string) constant( $name ) ) {
	550	+ return (string) constant( $name );
	551	+ }
	552	+ }
	553	+
	554	+ return self::derive_salt();
	555	+ }
	556	+
	557	+ /**
	558	+ * Build a stable per-site salt for installs that left Cache Key Prefix
	559	+ * blank. Distinct per install: the site URL separates sites sharing a
	560	+ * database, and DB name + table prefix separate installs sharing a domain
	561	+ * (e.g. subdirectory installs).
	562	+ *
	563	+ * This MUST stay byte-identical to the drop-in's xspeed_oc_salt(), which
	564	+ * is the harder constraint of the two: the drop-in loads from
	565	+ * wp-settings.php before `$wpdb` exists, so it can only read constants and
	566	+ * the `$table_prefix` global that wp-config.php itself assigns. Normally
	567	+ * the two never both run — enable() writes XSPEED_OC_SALT and both sides
	568	+ * read that constant — but where wp-config is NOT writable no constant is
	569	+ * ever written, and then both fallbacks are live at once in different
	570	+ * processes. Seeding them differently made "Test connection" verify a
	571	+ * different key space than the cache actually writes to: on ACL/namespaced
	572	+ * Redis (xCloud) that reports success while writes are refused, or reports
	573	+ * a failure while caching is fine. (PR #390 QA round 2, issue 2)
	574	+ *
	575	+ * Two specific traps this alignment closes:
	576	+ *
	577	+ * - WP_HOME / WP_SITEURL are OPTIONAL and absent from a stock
	578	+ * wp-config.php, so the drop-in's URL part is usually EMPTY while
	579	+ * get_site_url() always returns a real URL. Using get_site_url() here
	580	+ * therefore diverged on virtually every default install, not just an
	581	+ * exotic one — so this reads the same constants, and appends ABSPATH
	582	+ * on the same condition, rather than reaching for the richer value.
	583	+ * - `$wpdb->prefix` is PER-BLOG on multisite (`wp_2_` on a sub-site)
	584	+ * while `$table_prefix` is always the base prefix. The drop-in reads
	585	+ * the salt once and separates sub-sites with blog_prefix instead, so
	586	+ * `$table_prefix` is the value that matches; `$wpdb->prefix` would
	587	+ * hand every sub-site a different salt.
	588	+ *
	589	+ * @return string
	590	+ */
	591	+ private static function derive_salt(): string {
	592	+ global $table_prefix;
	593	+
	594	+ $url = '';
	595	+ if ( defined( 'WP_HOME' ) ) {
	596	+ $url = (string) WP_HOME;
	597	+ } elseif ( defined( 'WP_SITEURL' ) ) {
	598	+ $url = (string) WP_SITEURL;
	599	+ }
	600	+
	601	+ $parts = array(
	602	+ $url,
	603	+ defined( 'DB_NAME' ) ? (string) DB_NAME : '',
	604	+ isset( $table_prefix ) ? (string) $table_prefix : '',
	605	+ );
	606	+ if ( '' === $url ) {
	607	+ $parts[] = defined( 'ABSPATH' ) ? (string) ABSPATH : '';
	608	+ }
	609	+
	610	+ $seed = implode( '|', $parts );
	611	+ if ( '' === trim( $seed, '|' ) ) {
	612	+ // Nothing identifying available. Mirrors the drop-in's own
	613	+ // last-resort seed so the two still agree.
	614	+ $seed = 'xspeed';
	615	+ }
	616	+
	617	+ return 'xs' . substr( md5( $seed ), 0, 12 );
	618	+ }
	619	+
	620	+ /**
	621	+ * Build a probe key for the write-verification round-trip. It must land in
	622	+ * the same key space the drop-in writes to, so an ACL namespace restriction
	623	+ * (~<prefix>:*) is exercised. The drop-in salts keys as
	624	+ * `{salt}:{prefix}:{group}:{key}`, so prefixing the probe with the same
	625	+ * salt makes it match the allowed pattern on namespaced hosts (xCloud)
	626	+ * while staying harmless everywhere else.
	627	+ *
	628	+ * @param array $opts Settings array.
	629	+ * @return string
	630	+ */
	631	+ private static function probe_key( array $opts ): string {
	632	+ return self::effective_salt( $opts ) . ':xspeed-oc-probe';
	633	+ }
	634	+
	635	+ /**
	636	+ * Message for a connect-OK-but-write-denied result. Points ACL/namespaced
	637	+ * hosts at the fix (match the key prefix to the host's Redis Object Cache
	638	+ * Key), which is exactly the xCloud failure mode. (FBS-83118 OC-2)
	639	+ *
	640	+ * @param array $opts Settings array.
	641	+ * @param string $host Redis host.
	642	+ * @param int $port Redis port.
	643	+ * @return string
	644	+ */
	645	+ private static function write_denied_message( array $opts, string $host, int $port ): string {
	646	+ $has_prefix = '' !== self::str( $opts, 'key_prefix', '' );
	647	+ $hint = $has_prefix
	648	+ ? 'The Redis user may lack write permission for this key prefix (NOPERM).'
	649	+ : 'On ACL/namespaced Redis (e.g. xCloud), set Cache key prefix to the host\'s "Redis Object Cache Key" so writes land in the permitted namespace.';
	650	+ return "Connected to Redis at {$host}:{$port}, but the cache could not store data. {$hint}";
	651	+ }
	652	+
	653	+ /**
	654	+ * Full plug-and-play enable: test → write wp-config constants → install
	655	+ * drop-in → verify. Reversible via disable(). Returns a structured result
	656	+ * the REST/UI layer surfaces directly.
	657	+ *
	658	+ * @param array $opts Settings array.
	659	+ * @return array{ok:bool,message:string,steps:array<string,bool>,test:array,detect:array}
	660	+ */
	661	+ public static function enable( array $opts, array $args = array() ): array {
	662	+ /*
	663	+ * Another plugin's object-cache.php is a switch, not an install: its
	664	+ * owner has to be out of the picture first or it puts its file back
	665	+ * (W3TC on the next admin request, LiteSpeed on its next save). The
	666	+ * panel always refused here while REST, CLI and MCP overwrote the
	667	+ * file, so every entry point now refuses unless the caller asked for
	668	+ * the switch. (#686)
	669	+ */
	670	+ if ( self::foreign_dropin_present() ) {
	671	+ if ( empty( $args['takeover'] ) ) {
	672	+ $owner = Object_Cache_Takeover::owner();
	673	+ return array(
	674	+ 'ok' => false,
	675	+ 'needs_takeover' => true,
	676	+ 'message' => Object_Cache_Takeover::refusal_message( $owner ),
	677	+ 'steps' => array(
	678	+ 'connection' => false,
	679	+ 'wp_config' => false,
	680	+ 'drop_in' => false,
	681	+ 'verified' => false,
	682	+ ),
	683	+ 'owner' => $owner,
	684	+ 'detect' => self::detect( true ),
	685	+ );
	686	+ }
	687	+ return Object_Cache_Takeover::run( $opts );
	688	+ }
	689	+
	690	+ // Enabling from scratch starts a new session, so an earlier switch's
	691	+ // record no longer describes anything to put back. Re-running enable
	692	+ // over our own drop-in (a re-sync, an import) keeps it.
	693	+ if ( ! self::is_our_dropin_present() ) {
	694	+ Object_Cache_Takeover::forget();
	695	+ }
	696	+ return self::install( $opts );
	697	+ }
	698	+
	699	+ /**
	700	+ * Test, write the wp-config block and install our drop-in. The shared
	701	+ * second half of enable() and of a switch from another plugin; neither
	702	+ * calls it while a foreign drop-in is in place.
	703	+ *
	704	+ * @param array $opts Settings array.
	705	+ * @param array|null $test A connection test already run moments ago.
	706	+ * @return array{ok:bool,message:string,steps:array<string,bool>,test:array,detect:array}
	707	+ */
	708	+ public static function install( array $opts, ?array $test = null ): array {
	709	+ $steps = array(
	710	+ 'connection' => false,
	711	+ 'wp_config' => false,
	712	+ 'drop_in' => false,
	713	+ 'verified' => false,
	714	+ );
	715	+
	716	+ // 1. Don't write anything until the backend actually answers.
	717	+ $test = $test ?? self::test_connection( $opts );
	718	+ if ( ! $test['ok'] ) {
	719	+ return array(
	720	+ 'ok' => false,
	721	+ 'message' => 'Could not enable: ' . $test['message'],
	722	+ 'steps' => $steps,
	723	+ 'test' => $test,
	724	+ 'detect' => self::detect( true ),
	725	+ );
	726	+ }
	727	+ $steps['connection'] = true;
	728	+
	729	+ // Values from an earlier xSpeed session are still in Redis (keys
	730	+ // have no TTL, `alloptions` included), and the drop-in would read
	731	+ // them back as current. Only when ours is not already the live cache:
	732	+ // re-running enable over a working install must not cool it.
	733	+ if ( ! self::our_dropin_is_live() ) {
	734	+ self::purge_namespace( $opts );
	735	+ }
	736	+
	737	+ // 2. Write the XSPEED_OC_* constants into wp-config.php.
	738	+ $steps['wp_config'] = self::write_wp_config( $opts );
	739	+
	740	+ // 3. Install our drop-in.
	741	+ $steps['drop_in'] = self::install_dropin();
	742	+
	743	+ // 4. Verify the drop-in is live (best-effort — wp_using_ext_object_cache
	744	+ // reflects state only after the drop-in loads on the NEXT request, so
	745	+ // we verify the file landed + constants are present this request).
	746	+ $detect = self::detect();
	747	+ $steps['verified'] = $detect['drop_in_installed'] && self::wp_config_has_block();
	748	+
	749	+ $all_ok = $steps['drop_in'] && ( $steps['wp_config'] || self::backend_uses_no_constants( $opts ) );
	750	+
	751	+ return array(
	752	+ 'ok' => $all_ok,
	753	+ 'message' => $all_ok
	754	+ ? 'Object cache enabled. Drop-in installed and configured automatically.'
	755	+ : ( $steps['drop_in']
	756	+ ? 'Drop-in installed, but wp-config.php is not writable — add the snippet manually (shown below).'
	757	+ : 'Could not install the object-cache drop-in (wp-content not writable).' ),
	758	+ 'steps' => $steps,
	759	+ 'test' => $test,
	760	+ 'detect' => $detect,
	761	+ );
	762	+ }
	763	+
	764	+ /**
	765	+ * Full reverse of enable(): remove drop-in + strip our wp-config block.
	766	+ *
	767	+ * @return array{ok:bool,message:string,steps:array<string,bool>,detect:array}
	768	+ */
	769	+ public static function disable( array $args = array() ): array {
	770	+ // A drop-in owned by another plugin is left in place by
	771	+ // remove_dropin(), which then reports success because nothing of ours
	772	+ // is there to remove. Reporting "disabled" for that is a lie: the site
	773	+ // still has someone else's object cache running. Say so instead.
	774	+ $dropin = defined( 'WP_CONTENT_DIR' ) ? WP_CONTENT_DIR . '/object-cache.php' : '';
	775	+ if ( '' !== $dropin && file_exists( $dropin ) && ! self::is_our_dropin_present() ) {
	776	+ return array(
	777	+ 'ok' => false,
	778	+ 'message' => 'The object-cache drop-in belongs to another plugin, so xSpeed left it alone. Turn its object cache off in that plugin instead.',
	779	+ 'steps' => array(
	780	+ 'drop_in' => false,
	781	+ 'wp_config' => false,
	782	+ ),
	783	+ 'detect' => self::detect( true ),
	784	+ );
	785	+ }
	786	+
	787	+ // Empty our namespace before the drop-in goes, so a later enable
	788	+ // never reads this session's values back. Our cache stays loaded
	789	+ // until this request ends, so whatever it writes after this point
	790	+ // (a restore's own option writes) is flushed again at shutdown.
	791	+ // (#686)
	792	+ if ( self::is_our_dropin_present() ) {
	793	+ if ( self::our_dropin_is_live() ) {
	794	+ self::flush();
	795	+ add_action( 'shutdown', array( __CLASS__, 'flush' ), PHP_INT_MAX );
	796	+ } elseif ( class_exists( __NAMESPACE__ . '\\Settings_Manager' ) ) {
	797	+ self::purge_namespace( (array) Settings_Manager::get( 'object-cache' ) );
	798	+ }
	799	+ }
	800	+
	801	+ $dropin_removed = self::remove_dropin();
	802	+ $config_removed = self::remove_wp_config();
	803	+
	804	+ /*
	805	+ * The sidecar is the config on a host where wp-config.php is read-only,
	806	+ * and it carries the Redis password. Leaving it behind would keep a
	807	+ * plaintext credential on disk for a feature the admin just switched
	808	+ * off, and a later re-enable would silently pick up stale credentials
	809	+ * from a file nothing in this path had touched.
	810	+ */
	811	+ self::delete_sidecar();
	812	+
	813	+ $message = $dropin_removed
	814	+ ? 'Object cache disabled. Drop-in removed and wp-config.php cleaned.'
	815	+ : 'Could not remove the drop-in — wp-content may not be writable.';
	816	+
	817	+ // Put back the plugin xSpeed switched from, when asked. Without the
	818	+ // ask, the record describes nothing any more.
	819	+ $restored = null;
	820	+ if ( $dropin_removed && ! empty( $args['restore'] ) ) {
	821	+ $restored = Object_Cache_Takeover::restore();
	822	+ $message .= ' ' . $restored['message'];
	823	+ } elseif ( $dropin_removed ) {
	824	+ // Not put back, but its namespace is cleared all the same, so a
	825	+ // later manual re-enable does not start from the switch's
	826	+ // snapshot.
	827	+ Object_Cache_Takeover::discard();
	828	+ }
	829	+
	830	+ return array(
	831	+ // Whether xSpeed's object cache is off. A restore that could not
	832	+ // complete is reported beside it, in `restored` and the message:
	833	+ // the disable itself still happened. (#687)
	834	+ 'ok' => $dropin_removed,
	835	+ 'restored' => null === $restored ? null : $restored['ok'],
	836	+ 'message' => $message,
	837	+ 'steps' => array(
	838	+ 'drop_in' => $dropin_removed,
	839	+ 'wp_config' => $config_removed,
	840	+ 'restored' => null !== $restored && $restored['ok'],
	841	+ ),
	842	+ 'detect' => self::detect( true ),
	843	+ );
	844	+ }
	845	+
	846	+ /**
	847	+ * Copy our object-cache.php template into wp-content/. Mirrors
	848	+ * Cache::install_dropin(): only overwrites our own file, backs up a
	849	+ * foreign drop-in before replacing it.
	850	+ */
	851	+ public static function install_dropin(): bool {
	852	+ $source = ( defined( 'XSPEED_DIR' ) ? XSPEED_DIR : plugin_dir_path( __DIR__ ) . '../' ) . 'includes/object-cache.php';
	853	+ $target = WP_CONTENT_DIR . '/object-cache.php';
	854	+ if ( ! file_exists( $source ) ) {
	855	+ return false;
	856	+ }
	857	+
	858	+ $fs = self::fs();
	859	+ if ( ! $fs ) {
	860	+ return false;
	861	+ }
	862	+
	863	+ $source_contents = $fs->get_contents( $source );
	864	+ if ( ! is_string( $source_contents ) ) {
	865	+ return false;
	866	+ }
	867	+
	868	+ if ( file_exists( $target ) ) {
	869	+ $existing = $fs->get_contents( $target );
	870	+ $is_xspeed = is_string( $existing ) && false !== strpos( $existing, self::DROPIN_TAG );
	871	+
	872	+ if ( $is_xspeed ) {
	873	+ if ( $existing === $source_contents ) {
	874	+ return true;
	875	+ }
	876	+ $written = (bool) $fs->put_contents( $target, $source_contents, FS_CHMOD_FILE );
	877	+ self::invalidate_compiled( $target );
	878	+ return $written;
	879	+ }
	880	+
	881	+ // Foreign drop-in — back it up before overwriting.
	882	+ $upload = wp_upload_dir( null, false );
	883	+ $basedir = isset( $upload['basedir'] ) ? trailingslashit( $upload['basedir'] ) . 'xspeed-backups' : false;
	884	+ if ( $basedir ) {
	885	+ if ( ! file_exists( $basedir ) ) {
	886	+ wp_mkdir_p( $basedir );
	887	+ }
	888	+ $backup = $basedir . '/object-cache.foreign-' . gmdate( 'Ymd-His' ) . '.php.bak';
	889	+ $fs->move( $target, $backup, true );
	890	+ } else {
	891	+ $fs->delete( $target );
	892	+ }
	893	+ }
	894	+
	895	+ $written = (bool) $fs->put_contents( $target, $source_contents, FS_CHMOD_FILE );
	896	+ self::invalidate_compiled( $target );
	897	+ return $written;
	898	+ }
	899	+
	900	+ /**
	901	+ * Remove our drop-in (only if it's ours). Returns true when no xSpeed
	902	+ * drop-in remains.
	903	+ */
	904	+ public static function remove_dropin(): bool {
	905	+ $target = WP_CONTENT_DIR . '/object-cache.php';
	906	+ if ( ! file_exists( $target ) ) {
	907	+ return true;
	908	+ }
	909	+ $fs = self::fs();
	910	+ if ( ! $fs ) {
	911	+ return false;
	912	+ }
	913	+ $contents = $fs->get_contents( $target );
	914	+ if ( is_string( $contents ) && false !== strpos( $contents, self::DROPIN_TAG ) ) {
	915	+ wp_delete_file( $target );
	916	+ self::invalidate_compiled( $target );
	917	+ return ! file_exists( $target );
	918	+ }
	919	+ // Not ours — leave it, but report success (nothing of ours to remove).
	920	+ return true;
	921	+ }
	922	+
	923	+ /**
	924	+ * Write the XSPEED_OC_* constants between our markers in wp-config.php.
	925	+ * Idempotent: replaces an existing block. Reversible via remove_wp_config().
	926	+ */
	927	+ /** Sidecar holding the config when wp-config.php cannot be written. */
	928	+ private const SIDECAR_FILE = 'xspeed-object-cache.php';
	929	+
	930	+ /**
	931	+ * Absolute path of the config sidecar.
	932	+ *
	933	+ * Lives beside the drop-in in wp-content/ rather than under
	934	+ * wp-content/cache/, which a purge empties -- losing the settings on the
	935	+ * next purge would be a far stranger bug than the one this solves.
	936	+ */
	937	+ public static function sidecar_path(): string {
	938	+ return WP_CONTENT_DIR . '/' . self::SIDECAR_FILE;
	939	+ }
	940	+
	941	+ /**
	942	+ * Write the config sidecar. Used when wp-config.php is not writable, which
	943	+ * is the norm on several managed hosts -- there the panel could otherwise
	944	+ * only ever tell the user to paste a snippet by hand.
	945	+ *
	946	+ * Written as PHP, not JSON: wp-content/ is web-reachable, and a .json here
	947	+ * would serve the Redis password to anyone who guessed the filename. A PHP
	948	+ * file with an ABSPATH guard returns nothing when requested directly.
	949	+ *
	950	+ * @param array<string,mixed> $opts Effective settings to persist.
	951	+ */
	952	+ public static function write_sidecar( array $opts ): bool {
	953	+ $fs = self::fs();
	954	+ if ( ! $fs ) {
	955	+ return false;
	956	+ }
	957	+
	958	+ $payload = array();
	959	+ foreach ( self::SIDECAR_KEYS as $key ) {
	960	+ if ( array_key_exists( $key, $opts ) ) {
	961	+ $payload[ $key ] = $opts[ $key ];
	962	+ }
	963	+ }
	964	+
	965	+ $body = "<?php\n"
	966	+ . "/**\n"
	967	+ . " * xSpeed object-cache configuration.\n"
	968	+ . " *\n"
	969	+ . " * Written by xSpeed because wp-config.php is not writable on this host.\n"
	970	+ . " * The drop-in reads this before WordPress loads. Edit the Object Cache\n"
	971	+ . " * panel rather than this file -- it is rewritten on every save.\n"
	972	+ . " */\n"
	973	+ . "defined( 'ABSPATH' ) || exit;\n\n"
	974	+ . 'return ' . var_export( $payload, true ) . ";\n";
	975	+
	976	+ /*
	977	+ * Write to a temp file and rename() into place. The drop-in `include`s
	978	+ * this file BEFORE WordPress loads, so a reader that catches a
	979	+ * half-written copy gets a PHP parse error -- a white screen on every
	980	+ * request, not a degraded cache. rename() within the same directory is
	981	+ * atomic on every filesystem WordPress supports, so a reader sees
	982	+ * either the whole old file or the whole new one.
	983	+ */
	984	+ $path = self::sidecar_path();
	985	+ $tmp = $path . '.' . wp_generate_password( 8, false ) . '.tmp';
	986	+
	987	+ if ( ! $fs->put_contents( $tmp, $body, FS_CHMOD_FILE ) ) {
	988	+ return false;
	989	+ }
	990	+ // phpcs:ignore WordPress.WP.AlternativeFunctions.rename_rename -- WP_Filesystem has no atomic move; rename() is the whole point here.
	991	+ if ( ! @rename( $tmp, $path ) ) { // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- failure is reported by the return value.
	992	+ $fs->delete( $tmp );
	993	+ return false;
	994	+ }
	995	+
	996	+ /*
	997	+ * Managed hosts -- the ones this sidecar exists for -- often run
	998	+ * opcache with validate_timestamps off, where `include` would keep
	999	+ * returning the previously compiled array however many times we
	1000	+ * rewrite the file. That is the exact panel-says-one-thing,
	1001	+ * runtime-does-another failure this change exists to remove.
	1002	+ */
	1003	+ if ( function_exists( 'opcache_invalidate' ) ) {
	1004	+ @opcache_invalidate( $path, true ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- opcache may be disabled or restricted; nothing to do either way.
	1005	+ }
	1006	+
	1007	+ self::forget_sidecar();
	1008	+ return true;
	1009	+ }
	1010	+
	1011	+ /**
	1012	+ * Remove the sidecar. Called when wp-config.php becomes writable again, so
	1013	+ * two sources can never disagree about the same setting.
	1014	+ */
	1015	+ public static function delete_sidecar(): bool {
	1016	+ $path = self::sidecar_path();
	1017	+ if ( ! file_exists( $path ) ) {
	1018	+ return true;
	1019	+ }
	1020	+ $fs = self::fs();
	1021	+ $ok = $fs ? (bool) $fs->delete( $path ) : false;
	1022	+ if ( $ok ) {
	1023	+ self::forget_sidecar();
	1024	+ }
	1025	+ return $ok;
	1026	+ }
	1027	+
	1028	+ /**
	1029	+ * Settings the sidecar carries. Mirrors the fields wp_config_block()
	1030	+ * emits, so the two storage paths describe the same configuration.
	1031	+ */
	1032	+ private const SIDECAR_KEYS = array(
	1033	+ 'backend',
	1034	+ 'redis_host',
	1035	+ 'redis_port',
	1036	+ 'redis_user',
	1037	+ 'redis_password',
	1038	+ 'redis_database',
	1039	+ 'memcached_host',
	1040	+ 'memcached_port',
	1041	+ 'key_prefix',
	1042	+ 'connection_timeout',
	1043	+ 'persistent',
	1044	+ );
	1045	+
	1046	+ /** Memoized sidecar contents; null until first read. */
	1047	+ private static $sidecar_cache = null;
	1048	+
	1049	+ /** Forget the memoized sidecar. */
	1050	+ public static function forget_sidecar(): void {
	1051	+ self::$sidecar_cache = null;
	1052	+ }
	1053	+
	1054	+ /**
	1055	+ * Read the sidecar, or an empty array when there is none.
	1056	+ *
	1057	+ * @return array<string,mixed>
	1058	+ */
	1059	+ public static function read_sidecar(): array {
	1060	+ if ( null !== self::$sidecar_cache ) {
	1061	+ return self::$sidecar_cache;
	1062	+ }
	1063	+ $path = self::sidecar_path();
	1064	+ if ( ! file_exists( $path ) || ! is_readable( $path ) ) {
	1065	+ self::$sidecar_cache = array();
	1066	+ return self::$sidecar_cache;
	1067	+ }
	1068	+ $data = include $path;
	1069	+ self::$sidecar_cache = is_array( $data ) ? $data : array();
	1070	+ return self::$sidecar_cache;
	1071	+ }
	1072	+
	1073	+ /**
	1074	+ * Host and port of the first server in a `$memcached_servers` global.
	1075	+ *
	1076	+ * Memcached has no constant convention the way Redis has WP_REDIS_*; this
	1077	+ * global IS the convention, and hosts write it in two shapes:
	1078	+ *
	1079	+ * array( array( 'host', 11211 ) ) // W3TC pair form
	1080	+ * array( 'default' => array( 'host:11211' ) ) // Memcached Object Cache
	1081	+ *
	1082	+ * Reading only the first left the second taking the whole "host:port"
	1083	+ * string as the hostname, or missing it entirely because its bucket is
	1084	+ * keyed `default` rather than 0.
	1085	+ *
	1086	+ * The drop-in carries `xspeed_oc_first_memcached_server()`, which must
	1087	+ * behave identically -- it loads before WordPress and cannot call this
	1088	+ * class. ObjectCacheConstantParityTest holds the two together. (#398)
	1089	+ *
	1090	+ * @param mixed $servers The global's value, unvalidated.
	1091	+ * @return array{0:?string,1:?int}|null Host and port, either possibly null.
	1092	+ */
	1093	+ public static function first_memcached_server( $servers ): ?array {
	1094	+ if ( ! is_array( $servers ) || array() === $servers ) {
	1095	+ return null;
	1096	+ }
	1097	+
	1098	+ $bucket = array_key_exists( 0, $servers ) ? $servers[0] : reset( $servers );
	1099	+
	1100	+ /*
	1101	+ * A bucket is EITHER a [host, port] pair or a list of server entries.
	1102	+ * Telling them apart by shape, not by nesting depth: descending into
	1103	+ * `array( 'mc.example', 11211 )` yields the host string and drops the
	1104	+ * port on the floor, which is the commonest form there is.
	1105	+ */
	1106	+ $entry = $bucket;
	1107	+ if ( is_array( $bucket ) && isset( $bucket[0] ) && is_array( $bucket[0] ) ) {
	1108	+ $entry = $bucket[0];
	1109	+ }
	1110	+
	1111	+ if ( is_array( $entry ) ) {
	1112	+ $host = isset( $entry[0] ) && ! is_array( $entry[0] ) ? (string) $entry[0] : null;
	1113	+ $port = isset( $entry[1] ) && ! is_array( $entry[1] ) ? (int) $entry[1] : null;
	1114	+ // A single-element list, array( 'host:port' ), is the keyed form's
	1115	+ // bucket rather than a pair -- fall through to the string parser.
	1116	+ if ( null !== $host && null === $port && is_string( $entry[0] ) && false !== strpos( $entry[0], ':' ) ) {
	1117	+ $entry = $entry[0];
	1118	+ } else {
	1119	+ return ( null === $host && null === $port ) ? null : array( $host, $port );
	1120	+ }
	1121	+ }
	1122	+
	1123	+ if ( ! is_string( $entry ) || '' === $entry ) {
	1124	+ return null;
	1125	+ }
	1126	+
	1127	+ // "host:port", or a bare host. Split only the LAST colon, and only when
	1128	+ // what follows is numeric -- a unix socket path is a host with no port.
	1129	+ $at = strrpos( $entry, ':' );
	1130	+ if ( false !== $at && ctype_digit( substr( $entry, $at + 1 ) ) ) {
	1131	+ return array( substr( $entry, 0, $at ), (int) substr( $entry, $at + 1 ) );
	1132	+ }
	1133	+ return array( $entry, null );
	1134	+ }
	1135	+
	1136	+ /**
	1137	+ * Names of the constants xSpeed itself wrote into wp-config.php.
	1138	+ *
	1139	+ * Ownership is decided by LOCATION, not by name. Our block is fenced by
	1140	+ * CONFIG_BEGIN / CONFIG_END, so a define inside it is one we wrote and a
	1141	+ * define anywhere else belongs to the host -- even when both are called
	1142	+ * `XSPEED_OC_HOST`, which is exactly what a user pasting our own snippet
	1143	+ * by hand produces.
	1144	+ *
	1145	+ * Judging by prefix instead is what made the panel treat xSpeed's own
	1146	+ * values as host-pinned: the field locked, the "manage this here" control
	1147	+ * could not unlock it, and Revert handed the field back to our snapshot
	1148	+ * rather than to the host. (#398)
	1149	+ *
	1150	+ * @return string[] Constant names, empty when the block is absent.
	1151	+ */
	1152	+
	1153	+ public static function our_constants(): array {
	1154	+ if ( null !== self::$our_constants_cache ) {
	1155	+ return self::$our_constants_cache;
	1156	+ }
	1157	+ $cache = array();
	1158	+
	1159	+ $wp_config = ABSPATH . 'wp-config.php';
	1160	+ if ( ! file_exists( $wp_config ) || ! is_readable( $wp_config ) ) {
	1161	+ self::$our_constants_cache = $cache;
	1162	+ return $cache;
	1163	+ }
	1164	+ // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- reading our own block; WP_Filesystem is not always initialised on the read path.
	1165	+ $config = (string) @file_get_contents( $wp_config ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- an unreadable wp-config just means "we own nothing".
	1166	+ if ( '' === $config ) {
	1167	+ self::$our_constants_cache = $cache;
	1168	+ return $cache;
	1169	+ }
	1170	+
	1171	+ $pattern = '/' . preg_quote( self::CONFIG_BEGIN, '/' ) . '(.*?)' . preg_quote( self::CONFIG_END, '/' ) . '/s';
	1172	+ if ( ! preg_match( $pattern, $config, $m ) ) {
	1173	+ self::$our_constants_cache = $cache;
	1174	+ return $cache;
	1175	+ }
	1176	+ if ( preg_match_all( "/define\\(\\s*'([A-Z0-9_]+)'/", $m[1], $names ) ) {
	1177	+ $cache = $names[1];
	1178	+ }
	1179	+ self::$our_constants_cache = $cache;
	1180	+ return $cache;
	1181	+ }
	1182	+
	1183	+ /**
	1184	+ * Memoized result of our_constants(); null until the block is first read.
	1185	+ *
	1186	+ * @var string[]|null
	1187	+ */
	1188	+ private static $our_constants_cache = null;
	1189	+
	1190	+ /**
	1191	+ * Forget the memoized block scan. Every write that changes the block must
	1192	+ * call this, or the same request keeps answering from the pre-write copy.
	1193	+ */
	1194	+ public static function forget_our_constants(): void {
	1195	+ self::$our_constants_cache = null;
	1196	+ }
	1197	+
	1198	+ public static function write_wp_config( array $opts, array $force = array() ): bool {
	1199	+ $fs = self::fs();
	1200	+ $wp_config = ABSPATH . 'wp-config.php';
	1201	+ if ( ! $fs || ! file_exists( $wp_config ) || ! $fs->is_writable( $wp_config ) ) {
	1202	+ /*
	1203	+ * wp-config.php is read-only on several managed hosts. Fall back to
	1204	+ * a sidecar in wp-content/ -- writable wherever the drop-in itself
	1205	+ * could be installed, so the panel keeps working instead of telling
	1206	+ * the user to paste a snippet by hand. (#398)
	1207	+ */
	1208	+ return self::write_sidecar( $opts );
	1209	+ }
	1210	+
	1211	+
	1212	+ $config = $fs->get_contents( $wp_config );
	1213	+ if ( ! is_string( $config ) ) {
	1214	+ return false;
	1215	+ }
	1216	+
	1217	+ $block = self::wp_config_block( $opts, $force );
	1218	+
	1219	+ // Replace an existing xSpeed block if present, else insert after <?php.
	1220	+ // IMPORTANT: $block is inserted via preg_replace_callback returning it
	1221	+ // VERBATIM — never as a preg_replace replacement string. In a
	1222	+ // replacement string, `\` and `$` are special (backref escapes), so a
	1223	+ // constant value ending in a backslash (e.g. a Redis password or key
	1224	+ // prefix like "secret\") or containing "$1" would corrupt the output:
	1225	+ // esc()'s "secret\\" collapses back to "secret\", producing
	1226	+ // 'secret\' ) — a PHP parse error that white-screens the whole site.
	1227	+ // The callback form treats $block as literal text. (FBS-82111 Bug 1)
	1228	+ $pattern = '/' . preg_quote( self::CONFIG_BEGIN, '/' ) . '.*?' . preg_quote( self::CONFIG_END, '/' ) . "\s*/s";
	1229	+ if ( preg_match( $pattern, $config ) ) {
	1230	+ $config = preg_replace_callback(
	1231	+ $pattern,
	1232	+ static function () use ( $block ) {
	1233	+ return $block;
	1234	+ },
	1235	+ $config,
	1236	+ 1
	1237	+ );
138	1238	} else {
139		- $lines[] = '// No snippet for backend: ' . $backend;
	1239	+ $config = preg_replace_callback(
	1240	+ '/(<\?php)/',
	1241	+ static function ( $m ) use ( $block ) {
	1242	+ return $m[1] . "\n" . $block;
	1243	+ },
	1244	+ $config,
	1245	+ 1
	1246	+ );
140	1247	}
141	1248
	1249	+ $written = (bool) $fs->put_contents( $wp_config, $config, FS_CHMOD_FILE );
	1250	+ if ( $written ) {
	1251	+ self::invalidate_compiled( $wp_config );
	1252	+ // The block just changed; a memoized scan from earlier in this
	1253	+ // request would still name the previous set. (#398)
	1254	+ self::forget_our_constants();
	1255	+
	1256	+ // Only NOW is the block durable, so only now is a sidecar left
	1257	+ // from an earlier read-only spell safely redundant. Deleting it
	1258	+ // before the write -- is_writable() is not a promise the write
	1259	+ // lands; get_contents() can fail, and put_contents() can fail on a
	1260	+ // full disk or an SELinux denial -- would drop the live config and
	1261	+ // leave the site on built-in defaults.
	1262	+ self::delete_sidecar();
	1263	+ }
	1264	+ return $written;
	1265	+ }
	1266	+
	1267	+ /**
	1268	+ * Strip our wp-config block. Returns true if the block is gone afterward.
	1269	+ */
	1270	+ public static function remove_wp_config(): bool {
	1271	+ $fs = self::fs();
	1272	+ $wp_config = ABSPATH . 'wp-config.php';
	1273	+ if ( ! $fs || ! file_exists( $wp_config ) ) {
	1274	+ return true;
	1275	+ }
	1276	+ if ( ! $fs->is_writable( $wp_config ) ) {
	1277	+ return false;
	1278	+ }
	1279	+ $config = $fs->get_contents( $wp_config );
	1280	+ if ( ! is_string( $config ) ) {
	1281	+ return false;
	1282	+ }
	1283	+ $pattern = '/' . preg_quote( self::CONFIG_BEGIN, '/' ) . '.*?' . preg_quote( self::CONFIG_END, '/' ) . "\s*/s";
	1284	+ $config = preg_replace( $pattern, '', $config );
	1285	+ $removed = (bool) $fs->put_contents( $wp_config, $config, FS_CHMOD_FILE );
	1286	+ if ( $removed ) {
	1287	+ self::invalidate_compiled( $wp_config );
	1288	+ // A scan from earlier in this request would still name the
	1289	+ // constants we just deleted, so origins() would report a field as
	1290	+ // ours -- editable -- when a host define is now the only source
	1291	+ // and the field should read as pinned.
	1292	+ self::forget_our_constants();
	1293	+ }
	1294	+ return $removed;
	1295	+ }
	1296	+
	1297	+ /**
	1298	+ * The marker-wrapped constants block written into wp-config.php. Uses
	1299	+ * XSPEED_OC_* names (our drop-in reads these first, then falls back to
	1300	+ * WP_REDIS_* for interop).
	1301	+ */
	1302	+ private static function wp_config_block( array $opts, array $force = array() ): string {
	1303	+ // Fields the caller has decided we own, whatever pinned_elsewhere()
	1304	+ // would otherwise say. Used when an admin saved an override: they were
	1305	+ // told the host's define would stop applying, and this is the write
	1306	+ // that makes that true. (#398)
	1307	+ self::$force_fields = $force;
	1308	+ $backend = (string) ( $opts['backend'] ?? 'redis' );
	1309	+ $lines = array( self::CONFIG_BEGIN );
	1310	+ $lines[] = "define( 'XSPEED_OC_BACKEND', '" . self::esc( $backend ) . "' );";
	1311	+
	1312	+ if ( 'memcached' === $backend ) {
	1313	+ // XSPEED_OC_MC_*, not the Redis pair: one shared name meant enabling
	1314	+ // Redis overwrote the Memcached host/port. (#398)
	1315	+ if ( ! self::pinned_elsewhere( 'memcached_host' ) ) {
	1316	+ $lines[] = "define( 'XSPEED_OC_MC_HOST', '" . self::esc( self::str( $opts, 'memcached_host', '127.0.0.1' ) ) . "' );";
	1317	+ }
	1318	+ if ( ! self::pinned_elsewhere( 'memcached_port' ) ) {
	1319	+ $lines[] = "define( 'XSPEED_OC_MC_PORT', " . self::int( $opts, 'memcached_port', 11211 ) . ' );';
	1320	+ }
	1321	+ } else {
	1322	+ if ( ! self::pinned_elsewhere( 'redis_host' ) ) {
	1323	+ $lines[] = "define( 'XSPEED_OC_HOST', '" . self::esc( self::str( $opts, 'redis_host', '127.0.0.1' ) ) . "' );";
	1324	+ }
	1325	+ if ( ! self::pinned_elsewhere( 'redis_port' ) ) {
	1326	+ $lines[] = "define( 'XSPEED_OC_PORT', " . self::int( $opts, 'redis_port', 6379 ) . ' );';
	1327	+ }
	1328	+ $user = self::str( $opts, 'redis_user', '' );
	1329	+ if ( '' !== $user && ! self::pinned_elsewhere( 'redis_user' ) ) {
	1330	+ $lines[] = "define( 'XSPEED_OC_USER', '" . self::esc( $user ) . "' );";
	1331	+ }
	1332	+ $pass = self::str( $opts, 'redis_password', '' );
	1333	+ if ( '' !== $pass && ! self::pinned_elsewhere( 'redis_password' ) ) {
	1334	+ $lines[] = "define( 'XSPEED_OC_PASSWORD', '" . self::esc( $pass ) . "' );";
	1335	+ }
	1336	+ if ( ! self::pinned_elsewhere( 'redis_database' ) ) {
	1337	+ $lines[] = "define( 'XSPEED_OC_DATABASE', " . self::int( $opts, 'redis_database', 0 ) . ' );';
	1338	+ }
	1339	+ if ( ! self::pinned_elsewhere( 'connection_timeout' ) ) {
	1340	+ $lines[] = "define( 'XSPEED_OC_TIMEOUT', " . self::int( $opts, 'connection_timeout', 1 ) . ' );';
	1341	+ }
	1342	+ if ( ! self::pinned_elsewhere( 'persistent' ) ) {
	1343	+ $lines[] = "define( 'XSPEED_OC_PERSISTENT', " . ( ! empty( $opts['persistent'] ) ? 'true' : 'false' ) . ' );';
	1344	+ }
	1345	+ }
	1346	+ // Always emit a salt (#390): a blank Cache Key Prefix derives a per-site
	1347	+ // value rather than leaving keys unnamespaced, which collides when
	1348	+ // several sites share one Redis/Memcached server.
	1349	+ //
	1350	+ // Unless a foreign define already owns it (#398). Emitting ours would
	1351	+ // outrank the host's WP_REDIS_PREFIX, and on an ACL/namespaced Redis a
	1352	+ // prefix that does not match the host's exactly means every write is
	1353	+ // denied with NOPERM -- so a derived salt there is worse than none.
	1354	+ // The host's define IS the namespace in that case, and it is already
	1355	+ // non-empty, so the collision #390 closes cannot reopen.
	1356	+ if ( ! self::pinned_elsewhere( 'key_prefix' ) ) {
	1357	+ $lines[] = "define( 'XSPEED_OC_SALT', '" . self::esc( self::effective_salt( $opts ) ) . "' );";
	1358	+ }
	1359	+ $lines[] = self::CONFIG_END;
	1360	+ self::$force_fields = array();
142	1361	return implode( "\n", $lines ) . "\n";
	1362	+ }
	1363	+
	1364	+ /**
	1365	+ * Fields the current block write owns outright. Set for the duration of one
	1366	+ * wp_config_block() call; see the $force parameter there.
	1367	+ *
	1368	+ * @var string[]
	1369	+ */
	1370	+ private static array $force_fields = array();
	1371	+
	1372	+ /**
	1373	+ * Is this field already pinned by a constant we are not about to write?
	1374	+ *
	1375	+ * Enable() resolves settings through Settings_Manager, so on a
	1376	+ * host-provisioned site those values came FROM wp-config in the first
	1377	+ * place -- typically WP_REDIS_*. Writing them back out under our own
	1378	+ * XSPEED_OC_* names, which outrank every alias, would freeze a snapshot:
	1379	+ * when the host later rotated the password, the site would keep
	1380	+ * authenticating with our stale copy and silently drop to a
	1381	+ * non-persistent cache. It would also re-emit a credential as a second
	1382	+ * plaintext literal, which is the thing sourcing it from a constant
	1383	+ * avoids. So leave the host's define alone and emit nothing for it. (#398)
	1384	+ */
	1385	+ private static function pinned_elsewhere( string $field ): bool {
	1386	+ if ( in_array( $field, self::$force_fields, true ) ) {
	1387	+ return false;
	1388	+ }
	1389	+ if ( ! class_exists( '\\XSpeed\\Settings_Manager' ) ) {
	1390	+ return false;
	1391	+ }
	1392	+ $module = \XSpeed\Module_Registry::get( 'object-cache' );
	1393	+ if ( ! $module ) {
	1394	+ return false;
	1395	+ }
	1396	+
	1397	+ // An admin who deliberately overrode this field asked us to shadow the
	1398	+ // host's define -- they were told so in as many words before the field
	1399	+ // unlocked. Protecting it here would silently drop their value on the
	1400	+ // next enable, which is the same silent-no-op failure the whole
	1401	+ // pinned-field contract exists to prevent. (#398)
	1402	+ if ( \XSpeed\Settings_Manager::is_overridden( 'object-cache', $field ) ) {
	1403	+ return false;
	1404	+ }
	1405	+
	1406	+ // Somebody else's define, anywhere in this field's list, is protected --
	1407	+ // even when our own XSPEED_OC_* copy currently outranks it. Testing only
	1408	+ // the WINNING constant made an override permanent in a subtler way: on
	1409	+ // revert we rewrote our copy with the host's value, our copy still
	1410	+ // outranked theirs, and a later rotation on their side was shadowed
	1411	+ // forever. Emitting nothing for the field lets the host's define surface
	1412	+ // again and keep surfacing. (#398)
	1413	+ return null !== \XSpeed\Settings_Manager::foreign_constant( 'object-cache', $field );
	1414	+ }
	1415	+
	1416	+ /**
	1417	+ * Is our marker block present in wp-config.php?
	1418	+ *
	1419	+ * Public so a caller can tell "we already manage constants here" from
	1420	+ * "this site never enabled the object cache" -- rewriting the block is
	1421	+ * right in the first case and would be an unasked-for file edit in the
	1422	+ * second. (#398)
	1423	+ */
	1424	+ public static function wp_config_has_our_block(): bool {
	1425	+ return self::wp_config_has_block();
	1426	+ }
	1427	+
	1428	+ private static function wp_config_has_block(): bool {
	1429	+ $wp_config = ABSPATH . 'wp-config.php';
	1430	+ if ( ! file_exists( $wp_config ) ) {
	1431	+ return false;
	1432	+ }
	1433	+ $fs = self::fs();
	1434	+ if ( ! $fs ) {
	1435	+ return false;
	1436	+ }
	1437	+ $config = $fs->get_contents( $wp_config );
	1438	+ return is_string( $config ) && false !== strpos( $config, self::CONFIG_BEGIN );
	1439	+ }
	1440	+
	1441	+ /**
	1442	+ * Memcached config goes through $memcached_servers (handled by our drop-in's
	1443	+ * defaults), so a non-writable wp-config isn't necessarily fatal for it.
	1444	+ */
	1445	+ private static function backend_uses_no_constants( array $opts ): bool {
	1446	+ return false; // both backends currently rely on the constants block
	1447	+ }
	1448	+
	1449	+ /**
	1450	+ * Initialised WP_Filesystem handle, or null. Plugin Check-compliant access.
	1451	+ *
	1452	+ * Forces the 'direct' transport when PHP can write the WordPress tree
	1453	+ * itself. Without this, WP_Filesystem() can fall back to the FTP transport
	1454	+ * (no credentials in a non-interactive context) and fatal in
	1455	+ * ftp_fget(). We only need 'direct' — these writes target wp-config.php /
	1456	+ * wp-content, both owned by the PHP user on a normal install.
	1457	+ */
	1458	+ /**
	1459	+ * Drop a file's compiled copy from OPcache after we rewrite or remove it.
	1460	+ *
	1461	+ * wp-config.php and object-cache.php are both compiled once and reused.
	1462	+ * With the default revalidate_freq of 2 seconds, and indefinitely where a
	1463	+ * host turns validate_timestamps off, requests right after a write still
	1464	+ * run the old code: the panel read "Off" and "Backend: unknown" just
	1465	+ * after a switch because the new block's constants were not defined yet,
	1466	+ * and the old drop-in was still the live cache. (#687)
	1467	+ *
	1468	+ * @param string $path Absolute file path.
	1469	+ */
	1470	+ public static function invalidate_compiled( string $path ): void {
	1471	+ if ( function_exists( 'wp_opcache_invalidate' ) ) {
	1472	+ wp_opcache_invalidate( $path, true );
	1473	+ } elseif ( function_exists( 'opcache_invalidate' ) ) {
	1474	+ @opcache_invalidate( $path, true ); // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- opcache may be disabled or restricted; nothing to do either way.
	1475	+ }
	1476	+ }
	1477	+
	1478	+ /**
	1479	+ * The direct filesystem, for Object_Cache_Takeover's copies and deletes.
	1480	+ *
	1481	+ * @return \WP_Filesystem_Base|null
	1482	+ */
	1483	+ public static function filesystem() {
	1484	+ return self::fs();
	1485	+ }
	1486	+
	1487	+ private static function fs() {
	1488	+ global $wp_filesystem;
	1489	+ if ( ! function_exists( 'WP_Filesystem' ) ) {
	1490	+ require_once ABSPATH . 'wp-admin/includes/file.php';
	1491	+ }
	1492	+
	1493	+ // Pin the method to 'direct' for this call so a missing FTP/SSH config
	1494	+ // can never trigger the credential-prompt / ftp_*() fatal path. Use a
	1495	+ // closure on the filter so we don't permanently alter global behaviour.
	1496	+ $force_direct = static function () {
	1497	+ return 'direct';
	1498	+ };
	1499	+ add_filter( 'filesystem_method', $force_direct, 99 );
	1500	+ $ok = WP_Filesystem();
	1501	+ remove_filter( 'filesystem_method', $force_direct, 99 );
	1502	+
	1503	+ if ( ! $ok || ! $wp_filesystem || 'direct' !== $wp_filesystem->method ) {
	1504	+ return null;
	1505	+ }
	1506	+ return $wp_filesystem;
143	1507	}
144	1508
145	1509	private static function sniff_drop_in_label( string $path ): string {
146	1510	$head = @file_get_contents( $path, false, null, 0, 2048 );