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ObjectCache::newAccelerator()   B

Complexity

Conditions 5
Paths 4

Size

Total Lines 11
Code Lines 7

Duplication

Lines 0
Ratio 0 %

Importance

Changes 0
Metric Value
cc 5
eloc 7
nc 4
nop 2
dl 0
loc 11
rs 8.8571
c 0
b 0
f 0
1
<?php
2
/**
3
 * Functions to get cache objects.
4
 *
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
7
 * the Free Software Foundation; either version 2 of the License, or
8
 * (at your option) any later version.
9
 *
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 * This program is distributed in the hope that it will be useful,
11
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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 * GNU General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License along
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 * with this program; if not, write to the Free Software Foundation, Inc.,
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 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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 * http://www.gnu.org/copyleft/gpl.html
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 *
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 * @file
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 * @ingroup Cache
22
 */
23
24
use MediaWiki\Logger\LoggerFactory;
25
use MediaWiki\MediaWikiServices;
26
27
/**
28
 * Functions to get cache objects
29
 *
30
 * The word "cache" has two main dictionary meanings, and both
31
 * are used in this factory class. They are:
32
 *
33
 *   - a) Cache (the computer science definition).
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 *        A place to store copies or computations on existing data for
35
 *        higher access speeds.
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 *   - b) Storage.
37
 *        A place to store lightweight data that is not canonically
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 *        stored anywhere else (e.g. a "hoard" of objects).
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 *
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 * The former should always use strongly consistent stores, so callers don't
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 * have to deal with stale reads. The latter may be eventually consistent, but
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 * callers can use BagOStuff:READ_LATEST to see the latest available data.
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 *
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 * Primary entry points:
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 *
46
 * - ObjectCache::getMainWANInstance()
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 *   Purpose: Memory cache.
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 *   Stored in the local data-center's main cache (keyspace different from local-cluster cache).
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 *   Delete events are broadcasted to other DCs main cache. See WANObjectCache for details.
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 *
51
 * - ObjectCache::getLocalServerInstance( $fallbackType )
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 *   Purpose: Memory cache for very hot keys.
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 *   Stored only on the individual web server (typically APC or APCu for web requests,
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 *   and EmptyBagOStuff in CLI mode).
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 *   Not replicated to the other servers.
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 *
57
 * - ObjectCache::getLocalClusterInstance()
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 *   Purpose: Memory storage for per-cluster coordination and tracking.
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 *   A typical use case would be a rate limit counter or cache regeneration mutex.
60
 *   Stored centrally within the local data-center. Not replicated to other DCs.
61
 *   Configured by $wgMainCacheType.
62
 *
63
 * - ObjectCache::getMainStashInstance()
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 *   Purpose: Ephemeral global storage.
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 *   Stored centrally within the primary data-center.
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 *   Changes are applied there first and replicated to other DCs (best-effort).
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 *   To retrieve the latest value (e.g. not from a replica DB), use BagOStuff::READ_LATEST.
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 *   This store may be subject to LRU style evictions.
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 *
70
 * - ObjectCache::getInstance( $cacheType )
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 *   Purpose: Special cases (like tiered memory/disk caches).
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 *   Get a specific cache type by key in $wgObjectCaches.
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 *
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 * All the above cache instances (BagOStuff and WANObjectCache) have their makeKey()
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 * method scoped to the *current* wiki ID. Use makeGlobalKey() to avoid this scoping
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 * when using keys that need to be shared amongst wikis.
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 *
78
 * @ingroup Cache
79
 */
80
class ObjectCache {
81
	/** @var BagOStuff[] Map of (id => BagOStuff) */
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	public static $instances = [];
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	/** @var WANObjectCache[] Map of (id => WANObjectCache) */
84
	public static $wanInstances = [];
85
86
	/**
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	 * Get a cached instance of the specified type of cache object.
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	 *
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	 * @param string $id A key in $wgObjectCaches.
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	 * @return BagOStuff
91
	 */
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	public static function getInstance( $id ) {
93
		if ( !isset( self::$instances[$id] ) ) {
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			self::$instances[$id] = self::newFromId( $id );
95
		}
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97
		return self::$instances[$id];
98
	}
99
100
	/**
101
	 * Get a cached instance of the specified type of WAN cache object.
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	 *
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	 * @since 1.26
104
	 * @param string $id A key in $wgWANObjectCaches.
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	 * @return WANObjectCache
106
	 */
107
	public static function getWANInstance( $id ) {
108
		if ( !isset( self::$wanInstances[$id] ) ) {
109
			self::$wanInstances[$id] = self::newWANCacheFromId( $id );
110
		}
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112
		return self::$wanInstances[$id];
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	}
114
115
	/**
116
	 * Create a new cache object of the specified type.
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	 *
118
	 * @param string $id A key in $wgObjectCaches.
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	 * @return BagOStuff
120
	 * @throws InvalidArgumentException
121
	 */
122
	public static function newFromId( $id ) {
123
		global $wgObjectCaches;
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125
		if ( !isset( $wgObjectCaches[$id] ) ) {
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			// Always recognize these ones
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			if ( $id === CACHE_NONE ) {
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Unused Code Bug introduced by
The strict comparison === seems to always evaluate to false as the types of $id (string) and CACHE_NONE (integer) can never be identical. Maybe you want to use a loose comparison == instead?
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128
				return new EmptyBagOStuff();
129
			} elseif ( $id === 'hash' ) {
130
				return new HashBagOStuff();
131
			}
132
133
			throw new InvalidArgumentException( "Invalid object cache type \"$id\" requested. " .
134
				"It is not present in \$wgObjectCaches." );
135
		}
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137
		return self::newFromParams( $wgObjectCaches[$id] );
138
	}
139
140
	/**
141
	 * Get the default keyspace for this wiki.
142
	 *
143
	 * This is either the value of the `CachePrefix` configuration variable,
144
	 * or (if the former is unset) the `DBname` configuration variable, with
145
	 * `DBprefix` (if defined).
146
	 *
147
	 * @return string
148
	 */
149
	public static function getDefaultKeyspace() {
150
		global $wgCachePrefix;
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		$keyspace = $wgCachePrefix;
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		if ( is_string( $keyspace ) && $keyspace !== '' ) {
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			return $keyspace;
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		}
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157
		return wfWikiID();
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	}
159
160
	/**
161
	 * Create a new cache object from parameters.
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	 *
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	 * @param array $params Must have 'factory' or 'class' property.
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	 *  - factory: Callback passed $params that returns BagOStuff.
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	 *  - class: BagOStuff subclass constructed with $params.
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	 *  - loggroup: Alias to set 'logger' key with LoggerFactory group.
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	 *  - .. Other parameters passed to factory or class.
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	 * @return BagOStuff
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	 * @throws InvalidArgumentException
170
	 */
171
	public static function newFromParams( $params ) {
0 ignored issues
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Coding Style introduced by
newFromParams uses the super-global variable $GLOBALS which is generally not recommended.

Instead of super-globals, we recommend to explicitly inject the dependencies of your class. This makes your code less dependent on global state and it becomes generally more testable:

// Bad
class Router
{
    public function generate($path)
    {
        return $_SERVER['HOST'].$path;
    }
}

// Better
class Router
{
    private $host;

    public function __construct($host)
    {
        $this->host = $host;
    }

    public function generate($path)
    {
        return $this->host.$path;
    }
}

class Controller
{
    public function myAction(Request $request)
    {
        // Instead of
        $page = isset($_GET['page']) ? intval($_GET['page']) : 1;

        // Better (assuming you use the Symfony2 request)
        $page = $request->query->get('page', 1);
    }
}
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172 View Code Duplication
		if ( isset( $params['loggroup'] ) ) {
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			$params['logger'] = LoggerFactory::getInstance( $params['loggroup'] );
174
		} else {
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			$params['logger'] = LoggerFactory::getInstance( 'objectcache' );
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		}
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		if ( !isset( $params['keyspace'] ) ) {
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			$params['keyspace'] = self::getDefaultKeyspace();
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		}
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		if ( isset( $params['factory'] ) ) {
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			return call_user_func( $params['factory'], $params );
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		} elseif ( isset( $params['class'] ) ) {
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			$class = $params['class'];
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			// Automatically set the 'async' update handler
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			$params['asyncHandler'] = isset( $params['asyncHandler'] )
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				? $params['asyncHandler']
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				: 'DeferredUpdates::addCallableUpdate';
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			// Enable reportDupes by default
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			$params['reportDupes'] = isset( $params['reportDupes'] )
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				? $params['reportDupes']
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				: true;
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			// Do b/c logic for SqlBagOStuff
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			if ( is_a( $class, SqlBagOStuff::class, true ) ) {
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				if ( isset( $params['server'] ) && !isset( $params['servers'] ) ) {
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					$params['servers'] = [ $params['server'] ];
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					unset( $params['server'] );
197
				}
198
				// In the past it was not required to set 'dbDirectory' in $wgObjectCaches
199
				if ( isset( $params['servers'] ) ) {
200
					foreach ( $params['servers'] as &$server ) {
201
						if ( $server['type'] === 'sqlite' && !isset( $server['dbDirectory'] ) ) {
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							$server['dbDirectory'] = MediaWikiServices::getInstance()
203
								->getMainConfig()->get( 'SQLiteDataDir' );
204
						}
205
					}
206
				}
207
			}
208
209
			// Do b/c logic for MemcachedBagOStuff
210
			if ( is_subclass_of( $class, MemcachedBagOStuff::class ) ) {
211
				if ( !isset( $params['servers'] ) ) {
212
					$params['servers'] = $GLOBALS['wgMemCachedServers'];
213
				}
214
				if ( !isset( $params['debug'] ) ) {
215
					$params['debug'] = $GLOBALS['wgMemCachedDebug'];
216
				}
217
				if ( !isset( $params['persistent'] ) ) {
218
					$params['persistent'] = $GLOBALS['wgMemCachedPersistent'];
219
				}
220
				if ( !isset( $params['timeout'] ) ) {
221
					$params['timeout'] = $GLOBALS['wgMemCachedTimeout'];
222
				}
223
			}
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			return new $class( $params );
225
		} else {
226
			throw new InvalidArgumentException( "The definition of cache type \""
227
				. print_r( $params, true ) . "\" lacks both "
228
				. "factory and class parameters." );
229
		}
230
	}
231
232
	/**
233
	 * Factory function for CACHE_ANYTHING (referenced from DefaultSettings.php)
234
	 *
235
	 * CACHE_ANYTHING means that stuff has to be cached, not caching is not an option.
236
	 * If a caching method is configured for any of the main caches ($wgMainCacheType,
237
	 * $wgMessageCacheType, $wgParserCacheType), then CACHE_ANYTHING will effectively
238
	 * be an alias to the configured cache choice for that.
239
	 * If no cache choice is configured (by default $wgMainCacheType is CACHE_NONE),
240
	 * then CACHE_ANYTHING will forward to CACHE_DB.
241
	 *
242
	 * @param array $params
243
	 * @return BagOStuff
244
	 */
245
	public static function newAnything( $params ) {
246
		global $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType;
247
		$candidates = [ $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType ];
248
		foreach ( $candidates as $candidate ) {
249
			if ( $candidate !== CACHE_NONE && $candidate !== CACHE_ANYTHING ) {
250
				return self::getInstance( $candidate );
251
			}
252
		}
253
254
		if ( MediaWikiServices::getInstance()->isServiceDisabled( 'DBLoadBalancer' ) ) {
255
			// The LoadBalancer is disabled, probably because
256
			// MediaWikiServices::disableStorageBackend was called.
257
			$candidate = CACHE_NONE;
258
		} else {
259
			$candidate = CACHE_DB;
260
		}
261
262
		return self::getInstance( $candidate );
263
	}
264
265
	/**
266
	 * Factory function for CACHE_ACCEL (referenced from DefaultSettings.php)
267
	 *
268
	 * This will look for any APC or APCu style server-local cache.
269
	 * A fallback cache can be specified if none is found.
270
	 *
271
	 *     // Direct calls
272
	 *     ObjectCache::getLocalServerInstance( $fallbackType );
273
	 *
274
	 *     // From $wgObjectCaches via newFromParams()
275
	 *     ObjectCache::getLocalServerInstance( [ 'fallback' => $fallbackType ] );
276
	 *
277
	 * @param int|string|array $fallback Fallback cache or parameter map with 'fallback'
278
	 * @return BagOStuff
279
	 * @throws InvalidArgumentException
280
	 * @since 1.27
281
	 */
282
	public static function getLocalServerInstance( $fallback = CACHE_NONE ) {
283
		$cache = MediaWikiServices::getInstance()->getLocalServerObjectCache();
284
		if ( $cache instanceof EmptyBagOStuff ) {
285
			if ( is_array( $fallback ) ) {
286
				$fallback = isset( $fallback['fallback'] ) ? $fallback['fallback'] : CACHE_NONE;
287
			}
288
			$cache = self::getInstance( $fallback );
289
		}
290
291
		return $cache;
292
	}
293
294
	/**
295
	 * Create a new cache object of the specified type.
296
	 *
297
	 * @since 1.26
298
	 * @param string $id A key in $wgWANObjectCaches.
299
	 * @return WANObjectCache
300
	 * @throws UnexpectedValueException
301
	 */
302
	public static function newWANCacheFromId( $id ) {
303
		global $wgWANObjectCaches, $wgObjectCaches;
304
305
		if ( !isset( $wgWANObjectCaches[$id] ) ) {
306
			throw new UnexpectedValueException(
307
				"Cache type \"$id\" requested is not present in \$wgWANObjectCaches." );
308
		}
309
310
		$params = $wgWANObjectCaches[$id];
311
		if ( !isset( $wgObjectCaches[$params['cacheId']] ) ) {
312
			throw new UnexpectedValueException(
313
				"Cache type \"{$params['cacheId']}\" is not present in \$wgObjectCaches." );
314
		}
315
		$params['store'] = $wgObjectCaches[$params['cacheId']];
316
317
		return self::newWANCacheFromParams( $params );
318
	}
319
320
	/**
321
	 * Create a new cache object of the specified type.
322
	 *
323
	 * @since 1.28
324
	 * @param array $params
325
	 * @return WANObjectCache
326
	 * @throws UnexpectedValueException
327
	 */
328
	public static function newWANCacheFromParams( array $params ) {
329
		foreach ( $params['channels'] as $action => $channel ) {
330
			$params['relayers'][$action] = MediaWikiServices::getInstance()->getEventRelayerGroup()
331
				->getRelayer( $channel );
332
			$params['channels'][$action] = $channel;
333
		}
334
		$params['cache'] = self::newFromParams( $params['store'] );
335 View Code Duplication
		if ( isset( $params['loggroup'] ) ) {
336
			$params['logger'] = LoggerFactory::getInstance( $params['loggroup'] );
337
		} else {
338
			$params['logger'] = LoggerFactory::getInstance( 'objectcache' );
339
		}
340
		$class = $params['class'];
341
342
		return new $class( $params );
343
	}
344
345
	/**
346
	 * Get the main cluster-local cache object.
347
	 *
348
	 * @since 1.27
349
	 * @return BagOStuff
350
	 */
351
	public static function getLocalClusterInstance() {
352
		global $wgMainCacheType;
353
354
		return self::getInstance( $wgMainCacheType );
355
	}
356
357
	/**
358
	 * Get the main WAN cache object.
359
	 *
360
	 * @since 1.26
361
	 * @return WANObjectCache
362
	 * @deprecated Since 1.28 Use MediaWikiServices::getMainWANCache()
363
	 */
364
	public static function getMainWANInstance() {
365
		return MediaWikiServices::getInstance()->getMainWANObjectCache();
366
	}
367
368
	/**
369
	 * Get the cache object for the main stash.
370
	 *
371
	 * Stash objects are BagOStuff instances suitable for storing light
372
	 * weight data that is not canonically stored elsewhere (such as RDBMS).
373
	 * Stashes should be configured to propagate changes to all data-centers.
374
	 *
375
	 * Callers should be prepared for:
376
	 *   - a) Writes to be slower in non-"primary" (e.g. HTTP GET/HEAD only) DCs
377
	 *   - b) Reads to be eventually consistent, e.g. for get()/getMulti()
378
	 * In general, this means avoiding updates on idempotent HTTP requests and
379
	 * avoiding an assumption of perfect serializability (or accepting anomalies).
380
	 * Reads may be eventually consistent or data might rollback as nodes flap.
381
	 * Callers can use BagOStuff:READ_LATEST to see the latest available data.
382
	 *
383
	 * @return BagOStuff
384
	 * @since 1.26
385
	 * @deprecated Since 1.28 Use MediaWikiServices::getMainObjectStash
386
	 */
387
	public static function getMainStashInstance() {
388
		return MediaWikiServices::getInstance()->getMainObjectStash();
389
	}
390
391
	/**
392
	 * Clear all the cached instances.
393
	 */
394
	public static function clear() {
395
		self::$instances = [];
396
		self::$wanInstances = [];
397
	}
398
}
399