redirection / models / redirect / redirect-cache.php

redirect-cache.php in Redirection 5.5.0, at models/redirect/redirect-cache.php

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1	<?php
2
3	/**
4	* Redirect caching.
5	*
6	* This is based on server requests and not database requests.
7	*
8	* The client requests a URL. We use the requested URL, the `cache_key` setting, and the plugin version, to look for a cache entry.
9	*
10	* The `cache_key` is updated each time any redirect is updated. This is because a URL can be affected by other redirects, such as regular expressions
11	* and redirects with dynamic conditions (i.e. cookie, login status etc).
12	*
13	* We include the plugin version as data can change between plugin versions, and it is safest to use new cache entries.
14	*
15	* If we have a cache hit then the data is used to perform the redirect.php
16	*
17	* If we do not have a cache hit then we request the URL from the database and perform redirect matches.
18	*
19	* After matching has been performed we then try and update the cache:
20	* - if no match was found, cache an empty result
21	* - if a match was found and no dynamic redirects were encountered, then cache that redirect only
22	* - if a match was found and dynamic redirects were involved then cache all redirects
23	*
24	* We have a maximum number of redirects that can be cached to avoid saturating the cache.
25	*/
26	class Redirect_Cache {
27	const EMPTY_VALUE = 'empty';
28	const CACHE_MAX = 10;
29
30	/**
31	* Singleton
32	*
33	* @var Redirect_Cache\|null
34	*/
35	private static $instance = null;
36
37	/**
38	* Array of URLs that have been cached
39	*
40	* @var array
41	*/
42	private $cached = [];
43
44	/**
45	* Cache key. Changed to current time whenever a redirect is updated.
46	*
47	* @var integer
48	*/
49	private $key = 0;
50
51	/**
52	* Initialiser
53	*
54	* @return Redirect_Cache
55	*/
56	public static function init() {
57	if ( is_null( self::$instance ) ) {
58	self::$instance = new Redirect_Cache();
59	}
60
61	return self::$instance;
62	}
63
64	/**
65	* Constructor
66	*/
67	public function __construct() {
68	$this->reset();
69	}
70
71	public function reset() {
72	$settings = red_get_options();
73	$this->key = $settings['cache_key'];
74	$this->cached = [];
75	}
76
77	/**
78	* Is the cache enabled?
79	*
80	* @return boolean
81	*/
82	public function can_cache() {
83	return $this->key > 0;
84	}
85
86	/**
87	* Get the current cache key
88	*
89	* @param string $url URL we are looking at.
90	* @return string
91	*/
92	private function get_key( $url ) {
93	return apply_filters( 'redirection_cache_key', md5( $url ) . '-' . (string) $this->key . '-' . REDIRECTION_VERSION );
94	}
95
96	/**
97	* Get the cache entry for a URL
98	*
99	* @param string $url Requested URL.
100	* @return Red_Item[]\|bool
101	*/
102	public function get( $url ) {
103	if ( ! $this->can_cache() ) {
104	return false;
105	}
106
107	$cache_key = $this->get_key( $url );
108
109	// Look in cache
110	$false = false;
111	$result = wp_cache_get( $cache_key, 'redirection', false, $false );
112
113	// If a result was found then remember we are using the cache so we don't need to re-save it later
114	if ( $result !== false ) {
115	$this->cached[ $url ] = true;
116	}
117
118	// Empty value is a special case. Storing [] in the cache doesn't work, so we store the special EMPTY_VALUE to represent []
119	if ( $result === self::EMPTY_VALUE ) {
120	return [];
121	}
122
123	return $result;
124	}
125
126	/**
127	* Set the cache for a URL
128	*
129	* @param string $url URL to cache.
130	* @param Red_Item\|false $matched The matched redirect.
131	* @param Red_Item[] $redirects All of the redirects the match the URL.
132	* @return boolean
133	*/
134	public function set( $url, $matched, $redirects ) {
135	if ( ! $this->can_cache() \|\| isset( $this->cached[ $url ] ) ) {
136	return false;
137	}
138
139	$cache_key = $this->get_key( $url );
140
141	// Default store the match redirect
142	$rows = [];
143	if ( $matched ) {
144	$rows[] = $matched;
145	}
146
147	// Are any of the redirects before, and including, the match a dynamic redirect?
148	$dynamic = $this->get_dynamic_matched( $redirects, $matched );
149	if ( count( $dynamic ) > 0 ) {
150	// Store all dynamic redirects
151	$rows = $dynamic;
152	}
153
154	// Have we exceeded our limit?
155	if ( count( $rows ) > self::CACHE_MAX ) {
156	return false;
157	}
158
159	$converted = $this->convert_to_rows( $rows );
160	$value = count( $converted ) === 0 ? self::EMPTY_VALUE : $converted;
161
162	wp_cache_set( $cache_key, $value, 'redirection' );
163
164	return true;
165	}
166
167	/**
168	* Convert a Red_Item to a format suitable for storing in the cache
169	*
170	* @param Red_Item[] $rows Redirects.
171	* @return array
172	*/
173	private function convert_to_rows( array $rows ) {
174	$converted = [];
175
176	foreach ( $rows as $row ) {
177	$converted[] = $row->to_sql();
178	}
179
180	return $converted;
181	}
182
183	/**
184	* If there are dynamic redirects before the matched redirect then return all dynamic redirects (including the matched one), otherwise return nothing.
185	*
186	* If the matched redirect is a static redirect then we include it in the list, but don't include any redirects after.
187	*
188	* @param Red_Item[] $redirects Array of redirects.
189	* @param Red_Item\|false $matched The matched item.
190	* @return Red_Item[]
191	*/
192	private function get_dynamic_matched( array $redirects, $matched ) {
193	$dynamic = [];
194
195	foreach ( $redirects as $redirect ) {
196	if ( $redirect->is_dynamic() ) {
197	$dynamic[] = $redirect;
198	}
199
200	// Is this the matched redirect?
201	if ( $matched === $redirect ) {
202	// Yes. Do we have any dynamic redirects so far?
203	if ( count( $dynamic ) === 0 ) {
204	// No. Just return an empty array
205	return [];
206	}
207
208	if ( ! $matched->is_dynamic() ) {
209	// We need to include the non-dynamic redirect in the list
210	return array_merge( $dynamic, [ $matched ] );
211	}
212	}
213	}
214
215	return $dynamic;
216	}
217	}
218