ObjectCache.php at 11.1.0-beta.1 · WooCommerce

woocommerce / src / Caching / ObjectCache.php

ObjectCache.php

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1	<?php
2
3	namespace Automattic\WooCommerce\Caching;
4
5	/**
6	* Base class for caching objects (or associative arrays) that have a unique identifier.
7	* At the very least, derived classes need to implement the 'get_object_type' method,
8	* but usually it will be convenient to override some of the other protected members.
9	*
10	* The actual caching is delegated to an instance of CacheEngine. By default WpCacheEngine is used,
11	* but a different engine can be used by either overriding the get_cache_engine_instance method
12	* or capturing the wc_object_cache_get_engine filter.
13	*
14	* Objects are identified by ids that are either integers or strings. The actual cache keys passed
15	* to the cache engine will be prefixed with the object type and a random string. The 'flush' operation
16	* just forces the generation a new prefix and lets the old cached objects expire.
17	*/
18	abstract class ObjectCache {
19
20	/**
21	* Expiration value to be passed to 'set' to use the value of $default_expiration.
22	*/
23	public const DEFAULT_EXPIRATION = -1;
24
25	/**
26	* Maximum expiration time value, in seconds, that can be passed to 'set'.
27	*/
28	public const MAX_EXPIRATION = MONTH_IN_SECONDS;
29
30	/**
31	* This needs to be set in each derived class.
32	*
33	* @var string
34	*/
35	private $object_type;
36
37	/**
38	* Default value for the duration of the objects in the cache, in seconds
39	* (may not be used depending on the cache engine used WordPress cache implementation).
40	*
41	* @var int
42	*/
43	protected $default_expiration = HOUR_IN_SECONDS;
44
45	/**
46	* Temporarily used when retrieving data in 'get'.
47	*
48	* @var array
49	*/
50	private $last_cached_data;
51
52	/**
53	* The cache engine to use.
54	*
55	* @var ?CacheEngine
56	*/
57	private $cache_engine = null;
58
59	/**
60	* Gets an identifier for the types of objects cached by this class.
61	* This identifier will be used to compose the keys passed to the cache engine.
62	* It must be unique for each class inheriting from ObjectCache.
63	*
64	* @return string
65	*/
66	abstract public function get_object_type(): string;
67
68	/**
69	* Creates a new instance of the class.
70	*
71	* @throws CacheException If get_object_type returns null or an empty string.
72	*/
73	public function __construct() {
74	$this->object_type = $this->get_object_type();
75	if ( empty( $this->object_type ) ) {
76	throw new CacheException( 'Class ' . get_class( $this ) . ' returns an empty value for get_object_type', $this );
77	}
78	}
79
80	/**
81	* Get the default expiration time for cached objects, in seconds.
82	*
83	* @return int
84	*/
85	public function get_default_expiration_value(): int {
86	return $this->default_expiration;
87	}
88
89	/**
90	* Get the cache engine to use and cache it internally.
91	*
92	* @return CacheEngine
93	*/
94	private function get_cache_engine(): CacheEngine {
95	if ( null === $this->cache_engine ) {
96	$engine = $this->get_cache_engine_instance();
97
98	/**
99	* Filters the underlying cache engine to be used by an instance of ObjectCache.
100	*
101	* @since 7.4.0
102	*
103	* @param CacheEngine $engine The cache engine to be used by default.
104	* @param ObjectCache $cache_instance The instance of ObjectCache that will use the cache engine.
105	* @returns CacheEngine The actual cache engine that will be used.
106	*/
107	$this->cache_engine = apply_filters( 'wc_object_cache_get_engine', $engine, $this );
108	}
109	return $this->cache_engine;
110	}
111
112	/**
113	* Add an object to the cache, or update an already cached object.
114	*
115	* @param object\|array $object The object to be cached.
116	* @param int\|string\|null $id Id of the object to be cached, if null, get_object_id will be used to get it.
117	* @param int $expiration Expiration of the cached data in seconds from the current time, or DEFAULT_EXPIRATION to use the default value.
118	* @return bool True on success, false on error.
119	* @throws CacheException Invalid parameter, or null id was passed and get_object_id returns null too.
120	*/
121	public function set( $object, $id = null, int $expiration = self::DEFAULT_EXPIRATION ): bool {
122	if ( null === $object ) {
123	throw new CacheException( "Can't cache a null value", $this, $id );
124	}
125
126	if ( ! is_array( $object ) && ! is_object( $object ) ) {
127	throw new CacheException( "Can't cache a non-object, non-array value", $this, $id );
128	}
129
130	if ( ! is_string( $id ) && ! is_int( $id ) && ! is_null( $id ) ) {
131	throw new CacheException( "Object id must be an int, a string, or null for 'set'", $this, $id );
132	}
133
134	$this->verify_expiration_value( $expiration );
135
136	$errors = $this->validate( $object );
137	if ( ! is_null( $errors ) ) {
138	try {
139	$id = $this->get_id_from_object_if_null( $object, $id );
140	} catch ( \Throwable $ex ) { // phpcs:ignore Generic.CodeAnalysis.EmptyStatement.DetectedCatch
141	// Nothing else to do, we won't be able to add any significant object id to the CacheException and that's it.
142	}
143
144	if ( count( $errors ) === 1 ) {
145	throw new CacheException( 'Object validation/serialization failed: ' . $errors[0], $this, $id, $errors );
146	} elseif ( ! empty( $errors ) ) {
147	throw new CacheException( 'Object validation/serialization failed', $this, $id, $errors );
148	}
149	}
150
151	$id = $this->get_id_from_object_if_null( $object, $id );
152
153	$this->last_cached_data = $object;
154	return $this->get_cache_engine()->cache_object(
155	$id,
156	$object,
157	self::DEFAULT_EXPIRATION === $expiration ? $this->default_expiration : $expiration,
158	$this->get_object_type()
159	);
160	}
161
162	/**
163	* Update an object in the cache, but only if an object is already cached with the same id.
164	*
165	* @param object\|array $object The new object that will replace the already cached one.
166	* @param int\|string\|null $id Id of the object to be cached, if null, get_object_id will be used to get it.
167	* @param int $expiration Expiration of the cached data in seconds from the current time, or DEFAULT_EXPIRATION to use the default value.
168	* @return bool True on success, false on error or if no object with the supplied id was cached.
169	* @throws CacheException Invalid parameter, or null id was passed and get_object_id returns null too.
170	*/
171	public function update_if_cached( $object, $id = null, int $expiration = self::DEFAULT_EXPIRATION ): bool {
172	$id = $this->get_id_from_object_if_null( $object, $id );
173
174	if ( ! $this->is_cached( $id ) ) {
175	return false;
176	}
177
178	return $this->set( $object, $id, $expiration );
179	}
180
181	/**
182	* Get the id from an object if the id itself is null.
183	*
184	* @param object\|array $object The object to get the id from.
185	* @param int\|string\|null $id An object id or null.
186	*
187	* @return int\|string\|null Passed $id if it wasn't null, otherwise id obtained from $object using get_object_id.
188	*
189	* @throws CacheException Passed $id is null and get_object_id returned null too.
190	*/
191	private function get_id_from_object_if_null( $object, $id ) {
192	if ( null === $id ) {
193	$id = $this->get_object_id( $object );
194	if ( null === $id ) {
195	throw new CacheException( "Null id supplied and the cache class doesn't implement get_object_id", $this );
196	}
197	}
198
199	return $id;
200	}
201
202	/**
203	* Check if the given expiration time value is valid, throw an exception if not.
204	*
205	* @param int $expiration Expiration time to check.
206	* @return void
207	* @throws CacheException Expiration time is negative or higher than MAX_EXPIRATION.
208	*/
209	private function verify_expiration_value( int $expiration ): void {
210	if ( self::DEFAULT_EXPIRATION !== $expiration && ( ( $expiration < 1 ) \|\| ( $expiration > self::MAX_EXPIRATION ) ) ) {
211	throw new CacheException( 'Invalid expiration value, must be ObjectCache::DEFAULT_EXPIRATION or a value between 1 and ObjectCache::MAX_EXPIRATION', $this );
212	}
213	}
214
215	/**
216	* Retrieve a cached object, and if no object is cached with the given id,
217	* try to get one via get_from_datastore method or by supplying a callback and then cache it.
218	*
219	* If you want to provide a callable but still use the default expiration value,
220	* pass "ObjectCache::DEFAULT_EXPIRATION" as the second parameter.
221	*
222	* @param int\|string $id The id of the object to retrieve.
223	* @param int $expiration Expiration of the cached data in seconds from the current time, used if an object is retrieved from datastore and cached.
224	* @param callable\|null $get_from_datastore_callback Optional callback to get the object if it's not cached, it must return an object/array or null.
225	* @return object\|array\|null Cached object, or null if it's not cached and can't be retrieved from datastore or via callback.
226	* @throws CacheException Invalid id parameter.
227	*/
228	public function get( $id, int $expiration = self::DEFAULT_EXPIRATION, ?callable $get_from_datastore_callback = null ) {
229	if ( ! is_string( $id ) && ! is_int( $id ) ) {
230	throw new CacheException( "Object id must be an int or a string for 'get'", $this );
231	}
232
233	$this->verify_expiration_value( $expiration );
234
235	$data = $this->get_cache_engine()->get_cached_object( $id, $this->get_object_type() );
236	if ( null === $data ) {
237	$object = null;
238	if ( $get_from_datastore_callback ) {
239	$object = $get_from_datastore_callback( $id );
240	}
241
242	if ( null === $object ) {
243	return null;
244	}
245	$this->set( $object, $id, $expiration );
246	$data = $this->last_cached_data;
247	}
248
249	return $data;
250	}
251
252	/**
253	* Remove an object from the cache.
254	*
255	* @param int\|string $id The id of the object to remove.
256	* @return bool True if the object is removed from the cache successfully, false otherwise (because the object wasn't cached or for other reason).
257	*/
258	public function remove( $id ): bool {
259	return $this->get_cache_engine()->delete_cached_object( $id, $this->get_object_type() );
260	}
261
262	/**
263	* Remove all the objects from the cache.
264	*
265	* @return bool True on success, false on error.
266	*/
267	public function flush(): bool {
268	return $this->get_cache_engine()->delete_cache_group( $this->get_object_type() );
269	}
270
271	/**
272	* Is a given object cached?
273	*
274	* @param int\|string $id The id of the object to check.
275	* @return bool True if there's a cached object with the specified id.
276	*/
277	public function is_cached( $id ): bool {
278	return $this->get_cache_engine()->is_cached( $id, $this->get_object_type() );
279	}
280
281	/**
282	* Get the id of an object. This is used by 'set' when a null id is passed.
283	* If the object id can't be determined the method must return null.
284	*
285	* @param array\|object $object The object to get the id for.
286	* @return int\|string\|null
287	*/
288	abstract protected function get_object_id( $object );
289
290	/**
291	* Validate an object before it's cached.
292	*
293	* @param array\|object $object Object to validate.
294	* @return array\|null An array with validation error messages, null or an empty array if there are no errors.
295	*/
296	abstract protected function validate( $object ): ?array;
297
298	/**
299	* Get the instance of the cache engine to use.
300	*
301	* @return CacheEngine
302	*/
303	protected function get_cache_engine_instance(): CacheEngine {
304	return wc_get_container()->get( WPCacheEngine::class );
305	}
306
307	/**
308	* Get a random string to be used to compose the cache key prefix.
309	* It should return a different string each time.
310	*
311	* @return string
312	*/
313	protected function get_random_string(): string {
314	return dechex( microtime( true ) * 1000 ) . bin2hex( random_bytes( 8 ) );
315	}
316	}
317