powered-cache / includes / dropins / redis-object-cache.php

redis-object-cache.php in Powered Cache – Caching and Optimization for WordPress – Easily Improve PageSpeed & Web Vitals Score 2.0.2, at includes/dropins/redis-object-cache.php

1,482 lines 44.6 KB

Raw Download Zip

1	<?php
2
3	// WP Redis
4	// This file needs to be symlinked or copied to wp-content/object-cache.php
5
6	// Users with setups where multiple installs share a common wp-config.php or $table_prefix
7	// can use this to guarantee uniqueness for the keys generated by this object cache.
8	if ( ! defined( 'WP_CACHE_KEY_SALT' ) ) {
9	define( 'WP_CACHE_KEY_SALT', '' );
10	}
11
12	if ( ! defined( 'WP_REDIS_OBJECT_CACHE' ) ) {
13	define( 'WP_REDIS_OBJECT_CACHE', true );
14	}
15
16	if ( ! defined( 'WP_REDIS_USE_CACHE_GROUPS' ) ) {
17	define( 'WP_REDIS_USE_CACHE_GROUPS', false );
18	}
19
20	if ( ! defined( 'WP_REDIS_DEFAULT_EXPIRE_SECONDS' ) ) {
21	define( 'WP_REDIS_DEFAULT_EXPIRE_SECONDS', 0 );
22	}
23
24	/**
25	* Adds data to the cache, if the cache key doesn't already exist.
26	*
27	* @uses $wp_object_cache Object Cache Class
28	* @see WP_Object_Cache::add()
29	*
30	* @param int\|string $key The cache key to use for retrieval later
31	* @param mixed $data The data to add to the cache store
32	* @param string $group The group to add the cache to
33	* @param int $expire When the cache data should be expired
34	* @return bool False if cache key and group already exist, true on success
35	*/
36	function wp_cache_add( $key, $data, $group = '', $expire = WP_REDIS_DEFAULT_EXPIRE_SECONDS ) {
37	global $wp_object_cache;
38
39	return $wp_object_cache->add( $key, $data, $group, (int) $expire );
40	}
41
42	/**
43	* Closes the cache.
44	*
45	* This function has ceased to do anything since WordPress 2.5. The
46	* functionality was removed along with the rest of the persistent cache. This
47	* does not mean that plugins can't implement this function when they need to
48	* make sure that the cache is cleaned up after WordPress no longer needs it.
49	*
50	* @return bool Always returns True
51	*/
52	function wp_cache_close() {
53	return true;
54	}
55
56	/**
57	* Decrement numeric cache item's value
58	*
59	* @uses $wp_object_cache Object Cache Class
60	* @see WP_Object_Cache::decr()
61	*
62	* @param int\|string $key The cache key to increment
63	* @param int $offset The amount by which to decrement the item's value. Default is 1.
64	* @param string $group The group the key is in.
65	* @return false\|int False on failure, the item's new value on success.
66	*/
67	function wp_cache_decr( $key, $offset = 1, $group = '' ) {
68	global $wp_object_cache;
69
70	return $wp_object_cache->decr( $key, $offset, $group );
71	}
72
73	/**
74	* Removes the cache contents matching key and group.
75	*
76	* @uses $wp_object_cache Object Cache Class
77	* @see WP_Object_Cache::delete()
78	*
79	* @param int\|string $key What the contents in the cache are called
80	* @param string $group Where the cache contents are grouped
81	* @return bool True on successful removal, false on failure
82	*/
83	function wp_cache_delete( $key, $group = '' ) {
84	global $wp_object_cache;
85
86	return $wp_object_cache->delete( $key, $group );
87	}
88
89	/**
90	* Removes cache contents for a given group.
91	*
92	* @uses $wp_object_cache Object Cache Class
93	* @see WP_Object_Cache::delete_group()
94	*
95	* @param string $group Where the cache contents are grouped
96	* @return bool True on successful removal, false on failure
97	*/
98	function wp_cache_delete_group( $group ) {
99	global $wp_object_cache;
100	return $wp_object_cache->delete_group( $group );
101	}
102
103
104	/**
105	* Removes all cache items.
106	*
107	* @uses $wp_object_cache Object Cache Class
108	* @see WP_Object_Cache::flush()
109	*
110	* @return bool False on failure, true on success
111	*/
112	function wp_cache_flush() {
113	global $wp_object_cache;
114
115	return $wp_object_cache->flush();
116	}
117
118	/**
119	* Retrieves the cache contents from the cache by key and group.
120	*
121	* @uses $wp_object_cache Object Cache Class
122	* @see WP_Object_Cache::get()
123	*
124	* @param int\|string $key What the contents in the cache are called
125	* @param string $group Where the cache contents are grouped
126	* @param bool $force Whether to force an update of the local cache from the persistent cache (default is false)
127	* @param &bool $found Whether key was found in the cache. Disambiguates a return of false, a storable value.
128	* @return bool\|mixed False on failure to retrieve contents or the cache contents on success
129	*/
130	function wp_cache_get( $key, $group = '', $force = false, &$found = null ) {
131	global $wp_object_cache;
132
133	return $wp_object_cache->get( $key, $group, $force, $found );
134	}
135
136	/**
137	* Retrieves multiple values from the cache in one call.
138	*
139	* @see WP_Object_Cache::get_multiple()
140	* @global WP_Object_Cache $wp_object_cache Object cache global instance.
141	*
142	* @param array $keys Array of keys under which the cache contents are stored.
143	* @param string $group Optional. Where the cache contents are grouped. Default empty.
144	* @param bool $force Optional. Whether to force an update of the local cache
145	* from the persistent cache. Default false.
146	* @return array Array of values organized into groups.
147	*/
148	function wp_cache_get_multiple( $keys, $group = '', $force = false ) {
149	global $wp_object_cache;
150
151	return $wp_object_cache->get_multiple( $keys, $group, $force );
152	}
153
154	/**
155	* Increment numeric cache item's value
156	*
157	* @uses $wp_object_cache Object Cache Class
158	* @see WP_Object_Cache::incr()
159	*
160	* @param int\|string $key The cache key to increment
161	* @param int $offset The amount by which to increment the item's value. Default is 1.
162	* @param string $group The group the key is in.
163	* @return false\|int False on failure, the item's new value on success.
164	*/
165	function wp_cache_incr( $key, $offset = 1, $group = '' ) {
166	global $wp_object_cache;
167
168	return $wp_object_cache->incr( $key, $offset, $group );
169	}
170
171	/**
172	* Sets up Object Cache Global and assigns it.
173	*
174	* @global WP_Object_Cache $wp_object_cache WordPress Object Cache
175	*/
176	function wp_cache_init() {
177	global $wp_object_cache;
178
179	if ( ! ( $wp_object_cache instanceof WP_Object_Cache ) ) {
180	$wp_object_cache = new WP_Object_Cache;
181	}
182	}
183
184	/**
185	* Replaces the contents of the cache with new data.
186	*
187	* @uses $wp_object_cache Object Cache Class
188	* @see WP_Object_Cache::replace()
189	*
190	* @param int\|string $key What to call the contents in the cache
191	* @param mixed $data The contents to store in the cache
192	* @param string $group Where to group the cache contents
193	* @param int $expire When to expire the cache contents
194	* @return bool False if not exists, true if contents were replaced
195	*/
196	function wp_cache_replace( $key, $data, $group = '', $expire = WP_REDIS_DEFAULT_EXPIRE_SECONDS ) {
197	global $wp_object_cache;
198
199	return $wp_object_cache->replace( $key, $data, $group, (int) $expire );
200	}
201
202	/**
203	* Saves the data to the cache.
204	*
205	* @uses $wp_object_cache Object Cache Class
206	* @see WP_Object_Cache::set()
207	*
208	* @param int\|string $key What to call the contents in the cache
209	* @param mixed $data The contents to store in the cache
210	* @param string $group Where to group the cache contents
211	* @param int $expire When to expire the cache contents
212	* @return bool False on failure, true on success
213	*/
214	function wp_cache_set( $key, $data, $group = '', $expire = WP_REDIS_DEFAULT_EXPIRE_SECONDS ) {
215	global $wp_object_cache;
216
217	return $wp_object_cache->set( $key, $data, $group, (int) $expire );
218	}
219
220	/**
221	* Switch the interal blog id.
222	*
223	* This changes the blog id used to create keys in blog specific groups.
224	*
225	* @param int $blog_id Blog ID
226	*/
227	function wp_cache_switch_to_blog( $blog_id ) {
228	global $wp_object_cache;
229
230	return $wp_object_cache->switch_to_blog( $blog_id );
231	}
232
233	/**
234	* Adds a group or set of groups to the list of global groups.
235	*
236	* @param string\|array $groups A group or an array of groups to add
237	*/
238	function wp_cache_add_global_groups( $groups ) {
239	global $wp_object_cache;
240
241	return $wp_object_cache->add_global_groups( $groups );
242	}
243
244	/**
245	* Adds a group or set of groups to the list of non-persistent groups.
246	*
247	* @param string\|array $groups A group or an array of groups to add
248	*/
249	function wp_cache_add_non_persistent_groups( $groups ) {
250	global $wp_object_cache;
251
252	$wp_object_cache->add_non_persistent_groups( $groups );
253	}
254
255	/**
256	* Adds a group or set of groups to the list of groups that use Redis hashes.
257	*
258	* @param string\|array $groups A group or an array of groups to add.
259	*/
260	function wp_cache_add_redis_hash_groups( $groups ) {
261	global $wp_object_cache;
262
263	$wp_object_cache->add_redis_hash_groups( $groups );
264	}
265
266	/**
267	* Reset internal cache keys and structures. If the cache backend uses global
268	* blog or site IDs as part of its cache keys, this function instructs the
269	* backend to reset those keys and perform any cleanup since blog or site IDs
270	* have changed since cache init.
271	*
272	* This function is deprecated. Use wp_cache_switch_to_blog() instead of this
273	* function when preparing the cache for a blog switch. For clearing the cache
274	* during unit tests, consider using wp_cache_init(). wp_cache_init() is not
275	* recommended outside of unit tests as the performance penality for using it is
276	* high.
277	*
278	* @deprecated 3.5.0
279	*/
280	function wp_cache_reset() {
281	_deprecated_function( __FUNCTION__, '3.5' );
282
283	global $wp_object_cache;
284
285	return $wp_object_cache->reset();
286	}
287
288	/**
289	* WordPress Object Cache
290	*
291	* The WordPress Object Cache is used to save on trips to the database. The
292	* Object Cache stores all of the cache data to memory and makes the cache
293	* contents available by using a key, which is used to name and later retrieve
294	* the cache contents.
295	*
296	* The Object Cache can be replaced by other caching mechanisms by placing files
297	* in the wp-content folder which is looked at in wp-settings. If that file
298	* exists, then this file will not be included.
299	*/
300	class WP_Object_Cache {
301
302	/**
303	* Holds the cached objects
304	*
305	* @var array
306	* @access private
307	*/
308	var $cache = array();
309
310	/**
311	* The amount of times the cache data was already stored in the cache.
312	*
313	* @access private
314	* @var int
315	*/
316	var $cache_hits = 0;
317
318	/**
319	* Amount of times the cache did not have the request in cache
320	*
321	* @var int
322	* @access public
323	*/
324	var $cache_misses = 0;
325
326	/**
327	* The amount of times a request was made to Redis
328	*
329	* @access private
330	* @var int
331	*/
332	var $redis_calls = array();
333
334	/**
335	* List of global groups
336	*
337	* @var array
338	* @access protected
339	*/
340	var $global_groups = array();
341
342	/**
343	* List of non-persistent groups
344	*
345	* @var array
346	* @access protected
347	*/
348	var $non_persistent_groups = array();
349
350	/**
351	* List of groups which use Redis hashes.
352	*
353	* @var array
354	* @access protected
355	*/
356	var $redis_hash_groups = array();
357
358	/**
359	* The blog prefix to prepend to keys in non-global groups.
360	*
361	* @var int
362	* @access private
363	*/
364	var $blog_prefix;
365
366	/**
367	* Whether or not Redis is connected
368	*
369	* @var bool
370	* @access private
371	*/
372	var $is_redis_connected = false;
373
374	/**
375	* Whether or not the object cache thinks Redis needs a flush
376	*
377	* @var bool
378	* @access private
379	*/
380	var $do_redis_failback_flush = false;
381
382	/**
383	* The last triggered error
384	*/
385	var $last_triggered_error = '';
386
387	/**
388	* Whether or not to use true cache groups, instead of flattening.
389	*
390	* @var bool
391	* @access private
392	*/
393	const USE_GROUPS = WP_REDIS_USE_CACHE_GROUPS;
394
395	/**
396	* Adds data to the cache if it doesn't already exist.
397	*
398	* @uses WP_Object_Cache::_exists Checks to see if the cache already has data.
399	* @uses WP_Object_Cache::set Sets the data after the checking the cache
400	* contents existence.
401	*
402	* @param int\|string $key What to call the contents in the cache
403	* @param mixed $data The contents to store in the cache
404	* @param string $group Where to group the cache contents
405	* @param int $expire When to expire the cache contents
406	* @return bool False if cache key and group already exist, true on success
407	*/
408	public function add( $key, $data, $group = 'default', $expire = WP_REDIS_DEFAULT_EXPIRE_SECONDS ) {
409
410	if ( empty( $group ) ) {
411	$group = 'default';
412	}
413
414	if ( function_exists( 'wp_suspend_cache_addition' ) && wp_suspend_cache_addition() ) {
415	return false;
416	}
417
418	if ( $this->_exists( $key, $group ) ) {
419	return false;
420	}
421
422	return $this->set( $key, $data, $group, (int) $expire );
423	}
424
425	/**
426	* Sets the list of global groups.
427	*
428	* @param array $groups List of groups that are global.
429	*/
430	public function add_global_groups( $groups ) {
431	$groups = (array) $groups;
432
433	$groups = array_fill_keys( $groups, true );
434	$this->global_groups = array_merge( $this->global_groups, $groups );
435	}
436
437	/**
438	* Sets the list of non-persistent groups.
439	*
440	* @param array $groups List of groups that are non-persistent.
441	*/
442	public function add_non_persistent_groups( $groups ) {
443	$groups = (array) $groups;
444
445	$groups = array_fill_keys( $groups, true );
446	$this->non_persistent_groups = array_merge( $this->non_persistent_groups, $groups );
447	}
448
449	/**
450	* Sets the list of groups that use Redis hashes.
451	*
452	* @param array $groups List of groups that use Redis hashes.
453	*/
454	public function add_redis_hash_groups( $groups ) {
455	$groups = (array) $groups;
456
457	$groups = array_fill_keys( $groups, true );
458	$this->redis_hash_groups = array_merge( $this->redis_hash_groups, $groups );
459	}
460
461	/**
462	* Decrement numeric cache item's value
463	*
464	* @param int\|string $key The cache key to increment
465	* @param int $offset The amount by which to decrement the item's value. Default is 1.
466	* @param string $group The group the key is in.
467	* @return false\|int False on failure, the item's new value on success.
468	*/
469	public function decr( $key, $offset = 1, $group = 'default' ) {
470
471	if ( empty( $group ) ) {
472	$group = 'default';
473	}
474
475	// The key needs to exist in order to be decremented
476	if ( ! $this->_exists( $key, $group ) ) {
477	return false;
478	}
479
480	$offset = (int) $offset;
481
482	// If this isn't a persistant group, we have to sort this out ourselves, grumble grumble.
483	if ( ! $this->_should_persist( $group ) ) {
484	$existing = $this->_get_internal( $key, $group );
485	if ( empty( $existing ) \|\| ! is_numeric( $existing ) ) {
486	$existing = 0;
487	} else {
488	$existing -= $offset;
489	}
490	if ( $existing < 0 ) {
491	$existing = 0;
492	}
493	$this->_set_internal( $key, $group, $existing );
494	return $existing;
495	}
496
497	if ( $this->_should_use_redis_hashes( $group ) ) {
498	$redis_safe_group = $this->_key( '', $group );
499	$result = $this->_call_redis( 'hIncrBy', $redis_safe_group, $key, -$offset, $group );
500	if ( $result < 0 ) {
501	$result = 0;
502	$this->_call_redis( 'hSet', $redis_safe_group, $key, $result );
503	}
504	} else {
505	$id = $this->_key( $key, $group );
506	$result = $this->_call_redis( 'decrBy', $id, $offset );
507	if ( $result < 0 ) {
508	$result = 0;
509	$this->_call_redis( 'set', $id, $result );
510	}
511	}
512
513	if ( is_int( $result ) ) {
514	$this->_set_internal( $key, $group, $result );
515	}
516	return $result;
517	}
518
519	/**
520	* Remove the contents of the cache key in the group
521	*
522	* If the cache key does not exist in the group and $force parameter is set
523	* to false, then nothing will happen. The $force parameter is set to false
524	* by default.
525	*
526	* @param int\|string $key What the contents in the cache are called
527	* @param string $group Where the cache contents are grouped
528	* @param bool $force Optional. Whether to force the unsetting of the cache
529	* key in the group
530	* @return bool False if the contents weren't deleted and true on success
531	*/
532	public function delete( $key, $group = 'default', $force = false ) {
533
534	if ( empty( $group ) ) {
535	$group = 'default';
536	}
537
538	if ( ! $force && ! $this->_exists( $key, $group ) ) {
539	return false;
540	}
541
542	if ( $this->_should_persist( $group ) ) {
543	if ( $this->_should_use_redis_hashes( $group ) ) {
544	$redis_safe_group = $this->_key( '', $group );
545	$result = $this->_call_redis( 'hDel', $redis_safe_group, $key );
546	} else {
547	$id = $this->_key( $key, $group );
548	$result = $this->_call_redis( 'del', $id );
549	}
550	if ( 1 !== $result ) {
551	return false;
552	}
553	}
554
555	$this->_unset_internal( $key, $group );
556	return true;
557	}
558
559	/**
560	* Remove the contents of all cache keys in the group.
561	*
562	* @param string $group Where the cache contents are grouped.
563	* @return boolean True on success, false on failure.
564	*/
565	public function delete_group( $group ) {
566	if ( ! $this->_should_use_redis_hashes( $group ) ) {
567	return false;
568	}
569
570	$multisite_safe_group = $this->multisite && ! isset( $this->global_groups[ $group ] ) ? $this->blog_prefix . $group : $group;
571	$redis_safe_group = $this->_key( '', $group );
572	if ( $this->_should_persist( $group ) ) {
573	$result = $this->_call_redis( 'del', $redis_safe_group );
574	if ( 1 !== $result ) {
575	return false;
576	}
577	} elseif ( ! $this->_should_persist( $group ) && ! isset( $this->cache[ $multisite_safe_group ] ) ) {
578	return false;
579	}
580	unset( $this->cache[ $multisite_safe_group ] );
581	return true;
582	}
583
584	/**
585	* Clears the object cache of all data.
586	*
587	* By default, this will flush the session cache as well as Redis, but we
588	* can leave the redis cache intact if we want. This is helpful when, for
589	* instance, you're running a batch process and want to clear the session
590	* store to reduce the memory footprint, but you don't want to have to
591	* re-fetch all the values from the database.
592	*
593	* @param bool $redis Should we flush redis as well as the session cache?
594	* @return bool Always returns true
595	*/
596	public function flush( $redis = true ) {
597	$this->cache = array();
598	if ( $redis ) {
599	$this->_call_redis( 'flushdb' );
600	}
601
602	return true;
603	}
604
605	/**
606	* Retrieves the cache contents, if it exists
607	*
608	* The contents will be first attempted to be retrieved by searching by the
609	* key in the cache group. If the cache is hit (success) then the contents
610	* are returned.
611	*
612	* On failure, the number of cache misses will be incremented.
613	*
614	* @param int\|string $key What the contents in the cache are called
615	* @param string $group Where the cache contents are grouped
616	* @param string $force Whether to force a refetch rather than relying on the local cache (default is false)
617	* @param bool $found Optional. Whether the key was found in the cache. Disambiguates a return of false, a storable value. Passed by reference. Default null.
618	* @return bool\|mixed False on failure to retrieve contents or the cache contents on success
619	*/
620	public function get( $key, $group = 'default', $force = false, &$found = null ) {
621
622	if ( empty( $group ) ) {
623	$group = 'default';
624	}
625
626	// Key is set internally, so we can use this value
627	if ( $this->_isset_internal( $key, $group ) && ! $force ) {
628	$this->cache_hits += 1;
629	$found = true;
630	return $this->_get_internal( $key, $group );
631	}
632
633	// Not a persistent group, so don't try Redis if the value doesn't exist
634	// internally
635	if ( ! $this->_should_persist( $group ) ) {
636	$this->cache_misses += 1;
637	$found = false;
638	return false;
639	}
640
641	if ( $this->_should_use_redis_hashes( $group ) ) {
642	$redis_safe_group = $this->_key( '', $group );
643	$value = $this->_call_redis( 'hGet', $redis_safe_group, $key );
644	} else {
645	$id = $this->_key( $key, $group );
646	$value = $this->_call_redis( 'get', $id );
647	}
648
649	// PhpRedis returns `false` when the key doesn't exist
650	if ( false === $value ) {
651	$this->cache_misses += 1;
652	$found = false;
653	return false;
654	}
655
656	// All non-numeric values are serialized
657	$value = is_numeric( $value ) ? intval( $value ) : unserialize( $value );
658
659	$this->_set_internal( $key, $group, $value );
660	$this->cache_hits += 1;
661	$found = true;
662	return $value;
663	}
664
665	/**
666	* Retrieves multiple values from the cache in one call.
667	*
668	* @param array $keys Array of keys under which the cache contents are stored.
669	* @param string $group Optional. Where the cache contents are grouped. Default empty.
670	* @param bool $force Optional. Whether to force an update of the local cache
671	* from the persistent cache. Default false.
672	* @return array Array of values organized into groups.
673	*/
674	public function get_multiple( $keys, $group = 'default', $force = false ) {
675	if ( empty( $group ) ) {
676	$group = 'default';
677	}
678
679	$cache = array();
680	if ( ! $this->_should_persist( $group ) ) {
681	foreach ( $keys as $key ) {
682	$cache[ $key ] = $this->_isset_internal( $key, $group ) ? $this->_get_internal( $key, $group ) : false;
683	false !== $cache[ $key ] ? $this->cache_hits++ : $this->cache_misses++;
684	}
685	return $cache;
686	}
687
688	// Attempt to fetch values from the internal cache.
689	if ( ! $force ) {
690	foreach ( $keys as $key ) {
691	if ( $this->_isset_internal( $key, $group ) ) {
692	$cache[ $key ] = $this->_get_internal( $key, $group );
693	$this->cache_hits++;
694	}
695	}
696	}
697	$remaining_keys = array_values( array_diff( $keys, array_keys( $cache ) ) );
698	// If all keys were satisfied by the internal cache, we're sorted.
699	if ( empty( $remaining_keys ) ) {
700	return $cache;
701	}
702	if ( $this->_should_use_redis_hashes( $group ) ) {
703	$redis_safe_group = $this->_key( '', $group );
704	$results = $this->_call_redis( 'hmGet', $redis_safe_group, $remaining_keys );
705	$results = is_array( $results ) ? array_values( $results ) : $results;
706	} else {
707	$ids = array();
708	foreach ( $remaining_keys as $key ) {
709	$ids[] = $this->_key( $key, $group );
710	}
711	$results = $this->_call_redis( 'mget', $ids );
712	}
713	// Process the results from the Redis call.
714	foreach ( $remaining_keys as $i => $key ) {
715	$value = isset( $results[ $i ] ) ? $results[ $i ] : false;
716	if ( false !== $value ) {
717	// All non-numeric values are serialized
718	$value = is_numeric( $value ) ? intval( $value ) : unserialize( $value );
719	$this->_set_internal( $key, $group, $value );
720	$this->cache_hits++;
721	} else {
722	$this->cache_misses++;
723	}
724	$cache[ $key ] = $value;
725	}
726	// Make sure return values are returned in the order of the passed keys.
727	$return_cache = array();
728	foreach ( $keys as $key ) {
729	$return_cache[ $key ] = isset( $cache[ $key ] ) ? $cache[ $key ] : false;
730	}
731	return $return_cache;
732	}
733
734	/**
735	* Increment numeric cache item's value
736	*
737	* @param int\|string $key The cache key to increment
738	* @param int $offset The amount by which to increment the item's value. Default is 1.
739	* @param string $group The group the key is in.
740	* @return false\|int False on failure, the item's new value on success.
741	*/
742	public function incr( $key, $offset = 1, $group = 'default' ) {
743
744	if ( empty( $group ) ) {
745	$group = 'default';
746	}
747
748	// The key needs to exist in order to be incremented
749	if ( ! $this->_exists( $key, $group ) ) {
750	return false;
751	}
752
753	$offset = (int) $offset;
754
755	// If this isn't a persistant group, we have to sort this out ourselves, grumble grumble.
756	if ( ! $this->_should_persist( $group ) ) {
757	$existing = $this->_get_internal( $key, $group );
758	if ( empty( $existing ) \|\| ! is_numeric( $existing ) ) {
759	$existing = 1;
760	} else {
761	$existing += $offset;
762	}
763	if ( $existing < 0 ) {
764	$existing = 0;
765	}
766	$this->_set_internal( $key, $group, $existing );
767	return $existing;
768	}
769
770	if ( $this->_should_use_redis_hashes( $group ) ) {
771	$redis_safe_group = $this->_key( '', $group );
772	$result = $this->_call_redis( 'hIncrBy', $redis_safe_group, $key, $offset, $group );
773	if ( $result < 0 ) {
774	$result = 0;
775	$this->_call_redis( 'hSet', $redis_safe_group, $key, $result );
776	}
777	} else {
778	$id = $this->_key( $key, $group );
779	$result = $this->_call_redis( 'incrBy', $id, $offset );
780	if ( $result < 0 ) {
781	$result = 0;
782	$this->_call_redis( 'set', $id, $result );
783	}
784	}
785
786	if ( is_int( $result ) ) {
787	$this->_set_internal( $key, $group, $result );
788	}
789	return $result;
790	}
791
792	/**
793	* Replace the contents in the cache, if contents already exist
794	* @see WP_Object_Cache::set()
795	*
796	* @param int\|string $key What to call the contents in the cache
797	* @param mixed $data The contents to store in the cache
798	* @param string $group Where to group the cache contents
799	* @param int $expire When to expire the cache contents
800	* @return bool False if not exists, true if contents were replaced
801	*/
802	public function replace( $key, $data, $group = 'default', $expire = WP_REDIS_DEFAULT_EXPIRE_SECONDS ) {
803
804	if ( empty( $group ) ) {
805	$group = 'default';
806	}
807
808	if ( ! $this->_exists( $key, $group ) ) {
809	return false;
810	}
811
812	return $this->set( $key, $data, $group, (int) $expire );
813	}
814
815	/**
816	* Reset keys
817	*
818	* @deprecated 3.5.0
819	*/
820	public function reset() {
821	_deprecated_function( __FUNCTION__, '3.5', 'switch_to_blog()' );
822	}
823
824	/**
825	* Sets the data contents into the cache
826	*
827	* The cache contents is grouped by the $group parameter followed by the
828	* $key. This allows for duplicate ids in unique groups. Therefore, naming of
829	* the group should be used with care and should follow normal function
830	* naming guidelines outside of core WordPress usage.
831	*
832	* The $expire parameter is not used, because the cache will automatically
833	* expire for each time a page is accessed and PHP finishes. The method is
834	* more for cache plugins which use files.
835	*
836	* @param int\|string $key What to call the contents in the cache
837	* @param mixed $data The contents to store in the cache
838	* @param string $group Where to group the cache contents
839	* @param int $expire TTL for the data, in seconds
840	* @return bool Always returns true
841	*/
842	public function set( $key, $data, $group = 'default', $expire = WP_REDIS_DEFAULT_EXPIRE_SECONDS ) {
843
844	if ( empty( $group ) ) {
845	$group = 'default';
846	}
847
848	if ( is_object( $data ) ) {
849	$data = clone $data;
850	}
851
852	$this->_set_internal( $key, $group, $data );
853
854	if ( ! $this->_should_persist( $group ) ) {
855	return true;
856	}
857
858	// If this is an integer, store it as such. Otherwise, serialize it.
859	if ( ! is_numeric( $data ) \|\| intval( $data ) !== $data ) {
860	$data = serialize( $data );
861	}
862
863	// Redis doesn't support expire on hash group keys
864	if ( $this->_should_use_redis_hashes( $group ) ) {
865	$redis_safe_group = $this->_key( '', $group );
866	$this->_call_redis( 'hSet', $redis_safe_group, $key, $data );
867	return true;
868	}
869
870	$id = $this->_key( $key, $group );
871	if ( empty( $expire ) ) {
872	$this->_call_redis( 'set', $id, $data );
873	} else {
874	$this->_call_redis( 'setex', $id, $expire, $data );
875	}
876	return true;
877	}
878
879	/**
880	* Echoes the stats of the caching.
881	*
882	* Gives the cache hits, and cache misses. Also prints every cached group,
883	* key and the data.
884	*/
885	public function stats() {
886	$total_redis_calls = 0;
887	foreach ( $this->redis_calls as $method => $calls ) {
888	$total_redis_calls += $calls;
889	}
890	$out = array();
891	$out[] = '<p>';
892	$out[] = '<strong>Cache Hits:</strong>' . (int) $this->cache_hits . '<br />';
893	$out[] = '<strong>Cache Misses:</strong>' . (int) $this->cache_misses . '<br />';
894	$out[] = '<strong>Redis Client:</strong>' . get_class( $this->redis ) . '<br />';
895	$out[] = '<strong>Redis Calls:</strong>' . (int) $total_redis_calls . ':<br />';
896	foreach ( $this->redis_calls as $method => $calls ) {
897	$out[] = ' - ' . esc_html( $method ) . ': ' . (int) $calls . '<br />';
898	}
899	$out[] = '</p>';
900	$out[] = '<ul>';
901	foreach ( $this->cache as $group => $cache ) {
902	$out[] = '<li><strong>Group:</strong> ' . esc_html( $group ) . ' - ( ' . number_format( strlen( serialize( $cache ) ) / 1024, 2 ) . 'k )</li>';
903	}
904	$out[] = '</ul>';
905	// @codingStandardsIgnoreStart
906	echo implode( PHP_EOL, $out );
907	// @codingStandardsIgnoreEnd
908	}
909
910	/**
911	* Switch the interal blog id.
912	*
913	* This changes the blog id used to create keys in blog specific groups.
914	*
915	* @param int $blog_id Blog ID
916	*/
917	public function switch_to_blog( $blog_id ) {
918	$blog_id = (int) $blog_id;
919	$this->blog_prefix = $this->multisite ? $blog_id . ':' : '';
920	}
921
922	/**
923	* Utility function to determine whether a key exists in the cache.
924	*
925	* @access protected
926	*/
927	protected function _exists( $key, $group ) {
928	if ( $this->_isset_internal( $key, $group ) ) {
929	return true;
930	}
931
932	if ( ! $this->_should_persist( $group ) ) {
933	return false;
934	}
935
936	if ( $this->_should_use_redis_hashes( $group ) ) {
937	$redis_safe_group = $this->_key( '', $group );
938	return $this->_call_redis( 'hExists', $redis_safe_group, $key );
939	}
940	$id = $this->_key( $key, $group );
941	return $this->_call_redis( 'exists', $id );
942	}
943
944	/**
945	* Check whether there's a value in the internal object cache.
946	*
947	* @param string $key
948	* @param string $group
949	* @return boolean
950	*/
951	protected function _isset_internal( $key, $group ) {
952	if ( $this->_should_use_redis_hashes( $group ) ) {
953	$multisite_safe_group = $this->multisite && ! isset( $this->global_groups[ $group ] ) ? $this->blog_prefix . $group : $group;
954	return isset( $this->cache[ $multisite_safe_group ] ) && array_key_exists( $key, $this->cache[ $multisite_safe_group ] );
955	} else {
956	$key = $this->_key( $key, $group );
957	return array_key_exists( $key, $this->cache );
958	}
959	}
960
961	/**
962	* Get a value from the internal object cache
963	*
964	* @param string $key
965	* @param string $group
966	* @return mixed
967	*/
968	protected function _get_internal( $key, $group ) {
969	$value = null;
970	if ( $this->_should_use_redis_hashes( $group ) ) {
971	$multisite_safe_group = $this->multisite && ! isset( $this->global_groups[ $group ] ) ? $this->blog_prefix . $group : $group;
972	if ( isset( $this->cache[ $multisite_safe_group ] ) && array_key_exists( $key, $this->cache[ $multisite_safe_group ] ) ) {
973	$value = $this->cache[ $multisite_safe_group ][ $key ];
974	}
975	} else {
976	$key = $this->_key( $key, $group );
977	if ( array_key_exists( $key, $this->cache ) ) {
978	$value = $this->cache[ $key ];
979	}
980	}
981	if ( is_object( $value ) ) {
982	return clone $value;
983	}
984	return $value;
985	}
986
987	/**
988	* Set a value to the internal object cache
989	*
990	* @param string $key
991	* @param string $group
992	* @param mixed $value
993	*/
994	protected function _set_internal( $key, $group, $value ) {
995	if ( $this->_should_use_redis_hashes( $group ) ) {
996	$multisite_safe_group = $this->multisite && ! isset( $this->global_groups[ $group ] ) ? $this->blog_prefix . $group : $group;
997	if ( ! isset( $this->cache[ $multisite_safe_group ] ) ) {
998	$this->cache[ $multisite_safe_group ] = array();
999	}
1000	$this->cache[ $multisite_safe_group ][ $key ] = $value;
1001	} else {
1002	$key = $this->_key( $key, $group );
1003	$this->cache[ $key ] = $value;
1004	}
1005	}
1006
1007	/**
1008	* Unset a value from the internal object cache
1009	*
1010	* @param string $key
1011	* @param string $group
1012	*/
1013	protected function _unset_internal( $key, $group ) {
1014	if ( $this->_should_use_redis_hashes( $group ) ) {
1015	$multisite_safe_group = $this->multisite && ! isset( $this->global_groups[ $group ] ) ? $this->blog_prefix . $group : $group;
1016	if ( isset( $this->cache[ $multisite_safe_group ] ) && array_key_exists( $key, $this->cache[ $multisite_safe_group ] ) ) {
1017	unset( $this->cache[ $multisite_safe_group ][ $key ] );
1018	}
1019	} else {
1020	$key = $this->_key( $key, $group );
1021	if ( array_key_exists( $key, $this->cache ) ) {
1022	unset( $this->cache[ $key ] );
1023	}
1024	}
1025	}
1026
1027	/**
1028	* Utility function to generate the redis key for a given key and group.
1029	*
1030	* @param string $key The cache key.
1031	* @param string $group The cache group.
1032	* @return string A properly prefixed redis cache key.
1033	*/
1034	protected function _key( $key = '', $group = 'default' ) {
1035	if ( empty( $group ) ) {
1036	$group = 'default';
1037	}
1038
1039	if ( ! empty( $this->global_groups[ $group ] ) ) {
1040	$prefix = $this->global_prefix;
1041	} else {
1042	$prefix = $this->blog_prefix;
1043	}
1044
1045	return preg_replace( '/\s+/', '', WP_CACHE_KEY_SALT . "$prefix$group:$key" );
1046	}
1047
1048	/**
1049	* Does this group use persistent storage?
1050	*
1051	* @param string $group Cache group.
1052	* @return bool true if the group is persistent, false if not.
1053	*/
1054	protected function _should_persist( $group ) {
1055	return empty( $this->non_persistent_groups[ $group ] );
1056	}
1057
1058	/**
1059	* Should this group use Redis hashes?
1060	*
1061	* @param string $group Cache group.
1062	* @return bool True if the group should use Redis hashes, false if not.
1063	*/
1064	protected function _should_use_redis_hashes( $group ) {
1065	if ( self::USE_GROUPS \|\| ! empty( $this->redis_hash_groups[ $group ] ) ) {
1066	return true;
1067	}
1068	return false;
1069	}
1070
1071	/**
1072	* Wrapper method for connecting to Redis, which lets us retry the connection
1073	*/
1074	protected function _connect_redis() {
1075	global $redis_server;
1076
1077	$check_dependencies = array( $this, 'check_client_dependencies' );
1078	/**
1079	* Permits alternate dependency check mechanism to be used.
1080	*
1081	* @param callable $check_dependencies Callback to execute.
1082	*/
1083	$check_dependencies = apply_filters( 'wp_redis_check_client_dependencies_callback', $check_dependencies );
1084	$dependencies_ok = call_user_func( $check_dependencies );
1085	if ( true !== $dependencies_ok ) {
1086	$this->is_redis_connected = false;
1087	$this->missing_redis_message = $dependencies_ok;
1088	return $this->is_redis_connected;
1089	}
1090	$client_parameters = $this->build_client_parameters( $redis_server );
1091
1092	try {
1093	$client_connection = array( $this, 'prepare_client_connection' );
1094	/**
1095	* Permits alternate initial client connection mechanism to be used.
1096	*
1097	* @param callable $client_connection Callback to execute.
1098	*/
1099	$client_connection = apply_filters( 'wp_redis_prepare_client_connection_callback', $client_connection );
1100	$this->redis = call_user_func_array( $client_connection, array( $client_parameters ) );
1101	} catch ( Exception $e ) {
1102	$this->_exception_handler( $e );
1103	$this->is_redis_connected = false;
1104	return $this->is_redis_connected;
1105	}
1106
1107	$keys_methods = array(
1108	'auth' => 'auth',
1109	'database' => 'select',
1110	);
1111
1112	try {
1113	$setup_connection = array( $this, 'perform_client_connection' );
1114	/**
1115	* Permits alternate setup client connection mechanism to be used.
1116	*
1117	* @param callable $setup_connection Callback to execute.
1118	*/
1119	$setup_connection = apply_filters( 'wp_redis_perform_client_connection_callback', $setup_connection );
1120	call_user_func_array( $setup_connection, array( $this->redis, $client_parameters, $keys_methods ) );
1121	} catch ( Exception $e ) {
1122	$this->_exception_handler( $e );
1123	$this->is_redis_connected = false;
1124	return $this->is_redis_connected;
1125	}
1126
1127	$this->is_redis_connected = $this->redis->isConnected();
1128	if ( ! $this->is_redis_connected ) {
1129	$this->missing_redis_message = 'Warning! WP Redis object cache cannot connect to Redis server.';
1130	}
1131	return $this->is_redis_connected;
1132	}
1133
1134	/**
1135	* Are the required dependencies for connecting to Redis available?
1136	*
1137	* @return mixed True if the required dependencies are present, string if
1138	* not with a message describing the issue.
1139	*/
1140	public function check_client_dependencies() {
1141	if ( ! class_exists( 'Redis' ) ) {
1142	return 'Warning! PHPRedis extension is unavailable, which is required by WP Redis object cache.';
1143	}
1144	return true;
1145	}
1146
1147	/**
1148	* Builds an array to be passed to a function that will set up the Redis
1149	* client.
1150	*
1151	* @param array $redis_server Parameters used to construct a Redis client.
1152	* @return array Final parameters to use to contruct a Redis client with
1153	* with defaults applied.
1154	*/
1155	public function build_client_parameters( $redis_server ) {
1156	if ( empty( $redis_server ) ) {
1157	// Attempt to automatically load Pantheon's Redis config from the env.
1158	if ( isset( $_SERVER['CACHE_HOST'] ) ) {
1159	$redis_server = array(
1160	'host' => $_SERVER['CACHE_HOST'],
1161	'port' => $_SERVER['CACHE_PORT'],
1162	'auth' => $_SERVER['CACHE_PASSWORD'],
1163	'database' => isset( $_SERVER['CACHE_DB'] ) ? $_SERVER['CACHE_DB'] : 0,
1164	);
1165	} else {
1166	$redis_server = array(
1167	'host' => '127.0.0.1',
1168	'port' => 6379,
1169	'database' => 0,
1170	);
1171	}
1172	}
1173
1174	if ( file_exists( $redis_server['host'] ) && 'socket' === filetype( $redis_server['host'] ) ) { //unix socket connection
1175	//port must be null or socket won't connect
1176	$port = null;
1177	} else { //tcp connection
1178	$port = ! empty( $redis_server['port'] ) ? $redis_server['port'] : 6379;
1179	}
1180
1181	$defaults = array(
1182	'host' => $redis_server['host'],
1183	'port' => $port,
1184	'timeout' => 1000, // I multiplied this by 1000 so we'd have a common measure of ms instead of s and ms, need to make sure this gets divided by 1000
1185	'retry_interval' => 100,
1186	);
1187	// 1s timeout, 100ms delay between reconnections
1188
1189	// merging the defaults with the original $redis_server enables any
1190	// custom parameters to get sent downstream to the redis client.
1191	return array_replace_recursive( $redis_server, $defaults );
1192	}
1193
1194	/**
1195	* Constructs a PHPRedis Redis client.
1196	*
1197	* @param array $client_parameters Parameters used to construct a Redis client.
1198	* @return Redis Redis client.
1199	*/
1200	public function prepare_client_connection( $client_parameters ) {
1201	$redis = new Redis;
1202
1203	$redis->connect(
1204	$client_parameters['host'],
1205	$client_parameters['port'],
1206	// $client_parameters['timeout'] is sent in milliseconds,
1207	// connect() takes seconds, so divide by 1000
1208	$client_parameters['timeout'] / 1000,
1209	null,
1210	$client_parameters['retry_interval']
1211	);
1212
1213	return $redis;
1214	}
1215
1216	/**
1217	* Sets up the Redis connection (ie authentication and specific database).
1218	*
1219	* @param Redis $redis Redis client.
1220	* @param array $client_parameters Parameters used to configure Redis.
1221	* @param array $keys_methods Associative array of keys from
1222	* $client_parameters to use as method arguments for $redis.
1223	* @return bool True if successful.
1224	*/
1225	public function perform_client_connection( $redis, $client_parameters, $keys_methods ) {
1226	foreach ( $keys_methods as $key => $method ) {
1227	if ( ! isset( $client_parameters[ $key ] ) ) {
1228	continue;
1229	}
1230	try {
1231	$redis->$method( $client_parameters[ $key ] );
1232	} catch ( RedisException $e ) {
1233
1234	// PhpRedis throws an Exception when it fails a server call.
1235	// To prevent WordPress from fataling, we catch the Exception.
1236	throw new Exception( $e->getMessage(), $e->getCode(), $e );
1237	}
1238	}
1239	return true;
1240	}
1241
1242	/**
1243	* Wrapper method for calls to Redis, which fails gracefully when Redis is unavailable
1244	*
1245	* @param string $method
1246	* @param mixed $args
1247	* @return mixed
1248	*/
1249	protected function _call_redis( $method ) {
1250	global $wpdb;
1251
1252	$arguments = func_get_args();
1253	array_shift( $arguments ); // ignore $method
1254
1255	// $group is intended for the failback, and isn't passed to the Redis callback
1256	if ( 'hIncrBy' === $method ) {
1257	$group = array_pop( $arguments );
1258	}
1259
1260	if ( $this->is_redis_connected ) {
1261	try {
1262	if ( ! isset( $this->redis_calls[ $method ] ) ) {
1263	$this->redis_calls[ $method ] = 0;
1264	}
1265	$this->redis_calls[ $method ]++;
1266	$retval = call_user_func_array( array( $this->redis, $method ), $arguments );
1267	return $retval;
1268	} catch ( Exception $e ) {
1269	$retry_exception_messages = $this->retry_exception_messages();
1270	// PhpRedis throws an Exception when it fails a server call.
1271	// To prevent WordPress from fataling, we catch the Exception.
1272	if ( $this->exception_message_matches( $e->getMessage(), $retry_exception_messages ) ) {
1273
1274	$this->_exception_handler( $e );
1275
1276	// Attempt to refresh the connection if it was successfully established once
1277	// $this->is_redis_connected will be set inside _connect_redis()
1278	if ( $this->_connect_redis() ) {
1279	return call_user_func_array( array( $this, '_call_redis' ), array_merge( array( $method ), $arguments ) );
1280	}
1281	// Fall through to fallback below
1282	} else {
1283	throw $e;
1284	}
1285	}
1286	} // End if().
1287
1288	if ( $this->is_redis_failback_flush_enabled() && ! $this->do_redis_failback_flush && ! empty( $wpdb ) ) {
1289	if ( $this->multisite ) {
1290	$table = $wpdb->sitemeta;
1291	$col1 = 'meta_key';
1292	$col2 = 'meta_value';
1293	} else {
1294	$table = $wpdb->options;
1295	$col1 = 'option_name';
1296	$col2 = 'option_value';
1297	}
1298	// @codingStandardsIgnoreStart
1299	$wpdb->query( "INSERT IGNORE INTO {$table} ({$col1},{$col2}) VALUES ('wp_redis_do_redis_failback_flush',1)" );
1300	// @codingStandardsIgnoreEnd
1301	$this->do_redis_failback_flush = true;
1302	}
1303
1304	// Mock expected behavior from Redis for these methods
1305	switch ( $method ) {
1306	case 'incr':
1307	case 'incrBy':
1308	$val = $this->cache[ $arguments[0] ];
1309	$offset = isset( $arguments[1] ) && 'incrBy' === $method ? $arguments[1] : 1;
1310	$val = $val + $offset;
1311	return $val;
1312	case 'hIncrBy':
1313	$val = $this->_get_internal( $arguments[1], $group );
1314	return $val + $arguments[2];
1315	case 'decrBy':
1316	case 'decr':
1317	$val = $this->cache[ $arguments[0] ];
1318	$offset = isset( $arguments[1] ) && 'decrBy' === $method ? $arguments[1] : 1;
1319	$val = $val - $offset;
1320	return $val;
1321	case 'del':
1322	case 'hDel':
1323	return 1;
1324	case 'flushAll':
1325	case 'flushdb':
1326	case 'IsConnected':
1327	case 'exists':
1328	case 'get':
1329	case 'mget':
1330	case 'hGet':
1331	case 'hmGet':
1332	return false;
1333	}
1334
1335	}
1336
1337	/**
1338	* Returns a filterable array of expected Exception messages that may be thrown
1339	*
1340	* @return array Array of expected exception messages
1341	*/
1342	public function retry_exception_messages() {
1343	$retry_exception_messages = array( 'socket error on read socket', 'Connection closed', 'Redis server went away' );
1344	return apply_filters( 'wp_redis_retry_exception_messages', $retry_exception_messages );
1345	}
1346
1347	/**
1348	* Compares individual message to list of messages.
1349	*
1350	* @param string $error Message to compare
1351	* @param array $errors Array of messages to compare to
1352	* @return bool whether $error matches any items in $errors
1353	*/
1354	public function exception_message_matches( $error, $errors ) {
1355	foreach ( $errors as $message ) {
1356	$pattern = $this->_format_message_for_pattern( $message );
1357	$matches = (bool) preg_match( $pattern, $error );
1358	if ( $matches ) {
1359	return true;
1360	}
1361	}
1362	return false;
1363	}
1364
1365	/**
1366	* Prepends and appends '/' if not present in a string
1367	*
1368	* @param string $message Potential regex string that may need '/'
1369	* @return string Regex pattern
1370	*/
1371	protected function _format_message_for_pattern( $message ) {
1372	$var = $message;
1373	$var = '/' === $var[0] ? $var : '/' . $var;
1374	$var = '/' === $var[ strlen( $var ) - 1 ] ? $var : $var . '/';
1375	return $var;
1376	}
1377
1378	/**
1379	* Handles exceptions by triggering a php error.
1380	*
1381	* @param Exception $exception
1382	* @return null
1383	*/
1384	protected function _exception_handler( $exception ) {
1385	try {
1386	$this->last_triggered_error = 'WP Redis: ' . $exception->getMessage();
1387	// pc:fix
1388	$this->missing_redis_message = 'Redis Connection error, please check the credentials!';
1389	// Be friendly to developers debugging production servers by triggering an error
1390	// @codingStandardsIgnoreStart
1391	trigger_error( $this->last_triggered_error, E_USER_WARNING );
1392	// @codingStandardsIgnoreEnd
1393	} catch ( PHPUnit_Framework_Error_Warning $e ) {
1394	// PHPUnit throws an Exception when `trigger_error()` is called.
1395	// To ensure our tests (which expect Exceptions to be caught) continue to run,
1396	// we catch the PHPUnit exception and inspect the RedisException message
1397	}
1398	}
1399
1400	/**
1401	* Admin UI to let the end user know something about the Redis connection isn't working.
1402	*/
1403	public function wp_action_admin_notices_warn_missing_redis() {
1404	if ( ! current_user_can( 'manage_options' ) \|\| empty( $this->missing_redis_message ) ) {
1405	return;
1406	}
1407	echo '<div class="message error"><p>' . esc_html( $this->missing_redis_message ) . '</p></div>';
1408	}
1409
1410	/**
1411	* Whether or not wakeup flush is enabled
1412	*
1413	* @return bool
1414	*/
1415	private function is_redis_failback_flush_enabled() {
1416	if ( defined( 'WP_INSTALLING' ) && WP_INSTALLING ) {
1417	return false;
1418	} elseif ( defined( 'WP_REDIS_DISABLE_FAILBACK_FLUSH' ) && WP_REDIS_DISABLE_FAILBACK_FLUSH ) {
1419	return false;
1420	}
1421	return true;
1422	}
1423
1424	/**
1425	* Sets up object properties; PHP 5 style constructor
1426	*
1427	* @return null\|WP_Object_Cache If cache is disabled, returns null.
1428	*/
1429	public function __construct() {
1430	global $blog_id, $table_prefix, $wpdb;
1431
1432	$this->multisite = is_multisite();
1433	$this->blog_prefix = $this->multisite ? $blog_id . ':' : '';
1434
1435	if ( ! $this->_connect_redis() && function_exists( 'add_action' ) ) {
1436	add_action( 'admin_notices', array( $this, 'wp_action_admin_notices_warn_missing_redis' ) );
1437	}
1438
1439	if ( $this->is_redis_failback_flush_enabled() && ! empty( $wpdb ) ) {
1440	if ( $this->multisite ) {
1441	$table = $wpdb->sitemeta;
1442	$col1 = 'meta_key';
1443	$col2 = 'meta_value';
1444	} else {
1445	$table = $wpdb->options;
1446	$col1 = 'option_name';
1447	$col2 = 'option_value';
1448	}
1449	// @codingStandardsIgnoreStart
1450	$this->do_redis_failback_flush = (bool) $wpdb->get_results( "SELECT {$col2} FROM {$table} WHERE {$col1}='wp_redis_do_redis_failback_flush'" );
1451	// @codingStandardsIgnoreEnd
1452	if ( $this->is_redis_connected && $this->do_redis_failback_flush ) {
1453	$ret = $this->_call_redis( 'flushdb' );
1454	if ( $ret ) {
1455	// @codingStandardsIgnoreStart
1456	$wpdb->query( "DELETE FROM {$table} WHERE {$col1}='wp_redis_do_redis_failback_flush'" );
1457	// @codingStandardsIgnoreEnd
1458	$this->do_redis_failback_flush = false;
1459	}
1460	}
1461	}
1462
1463	$this->global_prefix = ( $this->multisite \|\| defined( 'CUSTOM_USER_TABLE' ) && defined( 'CUSTOM_USER_META_TABLE' ) ) ? '' : $table_prefix;
1464
1465	/**
1466	* @todo This should be moved to the PHP4 style constructor, PHP5
1467	* already calls __destruct()
1468	*/
1469	register_shutdown_function( array( $this, '__destruct' ) );
1470	}
1471
1472	/**
1473	* Will save the object cache before object is completely destroyed.
1474	*
1475	* Called upon object destruction, which should be when PHP ends.
1476	*
1477	* @return bool True value. Won't be used by PHP
1478	*/
1479	public function __destruct() {
1480	return true;
1481	}
1482	}