includes/objectcache/ObjectCache.php

   1 <?php
   2 /**
   3  * Functions to get cache objects.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * 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  *
  10  * 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
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @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).
  34  *        A place to store copies or computations on existing data for
  35  *        higher access speeds.
  36  *   - b) Storage.
  37  *        A place to store lightweight data that is not canonically
  38  *        stored anywhere else (e.g. a "hoard" of objects).
  39  *
  40  * The former should always use strongly consistent stores, so callers don't
  41  * have to deal with stale reads. The latter may be eventually consistent, but
  42  * callers can use BagOStuff:READ_LATEST to see the latest available data.
  43  *
  44  * Primary entry points:
  45  *
  46  * - ObjectCache::getLocalServerInstance( $fallbackType )
  47  *   Purpose: Memory cache for very hot keys.
  48  *   Stored only on the individual web server (typically APC or APCu for web requests,
  49  *   and EmptyBagOStuff in CLI mode).
  50  *   Not replicated to the other servers.
  51  *
  52  * - ObjectCache::getLocalClusterInstance()
  53  *   Purpose: Memory storage for per-cluster coordination and tracking.
  54  *   A typical use case would be a rate limit counter or cache regeneration mutex.
  55  *   Stored centrally within the local data-center. Not replicated to other DCs.
  56  *   Configured by $wgMainCacheType.
  57  *
  58  * - ObjectCache::getInstance( $cacheType )
  59  *   Purpose: Special cases (like tiered memory/disk caches).
  60  *   Get a specific cache type by key in $wgObjectCaches.
  61  *
  62  * All the above cache instances (BagOStuff and WANObjectCache) have their makeKey()
  63  * method scoped to the *current* wiki ID. Use makeGlobalKey() to avoid this scoping
  64  * when using keys that need to be shared amongst wikis.
  65  *
  66  * @ingroup Cache
  67  */
  68 class ObjectCache {
  69         /** @var BagOStuff[] Map of (id => BagOStuff) */
  70         public static $instances = [];
  71         /** @var WANObjectCache[] Map of (id => WANObjectCache) */
  72         public static $wanInstances = [];
  73
  74         /**
  75          * Get a cached instance of the specified type of cache object.
  76          *
  77          * @param string $id A key in $wgObjectCaches.
  78          * @return BagOStuff
  79          */
  80         public static function getInstance( $id ) {
  81                 if ( !isset( self::$instances[$id] ) ) {
  82                         self::$instances[$id] = self::newFromId( $id );
  83                 }
  84
  85                 return self::$instances[$id];
  86         }
  87
  88         /**
  89          * Get a cached instance of the specified type of WAN cache object.
  90          *
  91          * @since 1.26
  92          * @param string $id A key in $wgWANObjectCaches.
  93          * @return WANObjectCache
  94          * @deprecated since 1.34 Use MediaWikiServices::getMainWANObjectCache instead
  95          */
  96         public static function getWANInstance( $id ) {
  97                 wfDeprecated( __METHOD__, '1.34' );
  98                 if ( !isset( self::$wanInstances[$id] ) ) {
  99                         self::$wanInstances[$id] = self::newWANCacheFromId( $id );
 100                 }
 101
 102                 return self::$wanInstances[$id];
 103         }
 104
 105         /**
 106          * Create a new cache object of the specified type.
 107          *
 108          * @param string $id A key in $wgObjectCaches.
 109          * @return BagOStuff
 110          * @throws InvalidArgumentException
 111          */
 112         private static function newFromId( $id ) {
 113                 global $wgObjectCaches;
 114
 115                 if ( !isset( $wgObjectCaches[$id] ) ) {
 116                         // Always recognize these ones
 117                         if ( $id === CACHE_NONE ) {
 118                                 return new EmptyBagOStuff();
 119                         } elseif ( $id === 'hash' ) {
 120                                 return new HashBagOStuff();
 121                         }
 122
 123                         throw new InvalidArgumentException( "Invalid object cache type \"$id\" requested. " .
 124                                 "It is not present in \$wgObjectCaches." );
 125                 }
 126
 127                 return self::newFromParams( $wgObjectCaches[$id] );
 128         }
 129
 130         /**
 131          * Get the default keyspace for this wiki.
 132          *
 133          * This is either the value of the `CachePrefix` configuration variable,
 134          * or (if the former is unset) the `DBname` configuration variable, with
 135          * `DBprefix` (if defined).
 136          *
 137          * @return string
 138          */
 139         private static function getDefaultKeyspace() {
 140                 global $wgCachePrefix;
 141
 142                 $keyspace = $wgCachePrefix;
 143                 if ( is_string( $keyspace ) && $keyspace !== '' ) {
 144                         return $keyspace;
 145                 }
 146
 147                 return WikiMap::getCurrentWikiDbDomain()->getId();
 148         }
 149
 150         /**
 151          * Create a new cache object from parameters.
 152          *
 153          * @param array $params Must have 'factory' or 'class' property.
 154          *  - factory: Callback passed $params that returns BagOStuff.
 155          *  - class: BagOStuff subclass constructed with $params.
 156          *  - loggroup: Alias to set 'logger' key with LoggerFactory group.
 157          *  - .. Other parameters passed to factory or class.
 158          * @return BagOStuff
 159          * @throws InvalidArgumentException
 160          */
 161         public static function newFromParams( $params ) {
 162                 $params['logger'] = $params['logger'] ??
 163                         LoggerFactory::getInstance( $params['loggroup'] ?? 'objectcache' );
 164                 if ( !isset( $params['keyspace'] ) ) {
 165                         $params['keyspace'] = self::getDefaultKeyspace();
 166                 }
 167                 if ( isset( $params['factory'] ) ) {
 168                         return call_user_func( $params['factory'], $params );
 169                 } elseif ( isset( $params['class'] ) ) {
 170                         $class = $params['class'];
 171                         // Automatically set the 'async' update handler
 172                         $params['asyncHandler'] = $params['asyncHandler']
 173                                 ?? [ DeferredUpdates::class, 'addCallableUpdate' ];
 174                         // Enable reportDupes by default
 175                         $params['reportDupes'] = $params['reportDupes'] ?? true;
 176                         // Do b/c logic for SqlBagOStuff
 177                         if ( is_a( $class, SqlBagOStuff::class, true ) ) {
 178                                 if ( isset( $params['server'] ) && !isset( $params['servers'] ) ) {
 179                                         $params['servers'] = [ $params['server'] ];
 180                                         unset( $params['server'] );
 181                                 }
 182                                 // In the past it was not required to set 'dbDirectory' in $wgObjectCaches
 183                                 if ( isset( $params['servers'] ) ) {
 184                                         foreach ( $params['servers'] as &$server ) {
 185                                                 if ( $server['type'] === 'sqlite' && !isset( $server['dbDirectory'] ) ) {
 186                                                         $server['dbDirectory'] = MediaWikiServices::getInstance()
 187                                                                 ->getMainConfig()->get( 'SQLiteDataDir' );
 188                                                 }
 189                                         }
 190                                 }
 191                         }
 192
 193                         // Do b/c logic for MemcachedBagOStuff
 194                         if ( is_subclass_of( $class, MemcachedBagOStuff::class ) ) {
 195                                 if ( !isset( $params['servers'] ) ) {
 196                                         $params['servers'] = $GLOBALS['wgMemCachedServers'];
 197                                 }
 198                                 if ( !isset( $params['persistent'] ) ) {
 199                                         $params['persistent'] = $GLOBALS['wgMemCachedPersistent'];
 200                                 }
 201                                 if ( !isset( $params['timeout'] ) ) {
 202                                         $params['timeout'] = $GLOBALS['wgMemCachedTimeout'];
 203                                 }
 204                         }
 205                         return new $class( $params );
 206                 } else {
 207                         throw new InvalidArgumentException( "The definition of cache type \""
 208                                 . print_r( $params, true ) . "\" lacks both "
 209                                 . "factory and class parameters." );
 210                 }
 211         }
 212
 213         /**
 214          * Factory function for CACHE_ANYTHING (referenced from DefaultSettings.php)
 215          *
 216          * CACHE_ANYTHING means that stuff has to be cached, not caching is not an option.
 217          * If a caching method is configured for any of the main caches ($wgMainCacheType,
 218          * $wgMessageCacheType, $wgParserCacheType), then CACHE_ANYTHING will effectively
 219          * be an alias to the configured cache choice for that.
 220          * If no cache choice is configured (by default $wgMainCacheType is CACHE_NONE),
 221          * then CACHE_ANYTHING will forward to CACHE_DB.
 222          *
 223          * @param array $params
 224          * @return BagOStuff
 225          */
 226         public static function newAnything( $params ) {
 227                 global $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType;
 228                 $candidates = [ $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType ];
 229                 foreach ( $candidates as $candidate ) {
 230                         if ( $candidate !== CACHE_NONE && $candidate !== CACHE_ANYTHING ) {
 231                                 $cache = self::getInstance( $candidate );
 232                                 // CACHE_ACCEL might default to nothing if no APCu
 233                                 // See includes/ServiceWiring.php
 234                                 if ( !( $cache instanceof EmptyBagOStuff ) ) {
 235                                         return $cache;
 236                                 }
 237                         }
 238                 }
 239
 240                 if ( MediaWikiServices::getInstance()->isServiceDisabled( 'DBLoadBalancer' ) ) {
 241                         // The LoadBalancer is disabled, probably because
 242                         // MediaWikiServices::disableStorageBackend was called.
 243                         $candidate = CACHE_NONE;
 244                 } else {
 245                         $candidate = CACHE_DB;
 246                 }
 247
 248                 return self::getInstance( $candidate );
 249         }
 250
 251         /**
 252          * Factory function for CACHE_ACCEL (referenced from DefaultSettings.php)
 253          *
 254          * This will look for any APC or APCu style server-local cache.
 255          * A fallback cache can be specified if none is found.
 256          *
 257          *     // Direct calls
 258          *     ObjectCache::getLocalServerInstance( $fallbackType );
 259          *
 260          *     // From $wgObjectCaches via newFromParams()
 261          *     ObjectCache::getLocalServerInstance( [ 'fallback' => $fallbackType ] );
 262          *
 263          * @param int|string|array $fallback Fallback cache or parameter map with 'fallback'
 264          * @return BagOStuff
 265          * @throws InvalidArgumentException
 266          * @since 1.27
 267          */
 268         public static function getLocalServerInstance( $fallback = CACHE_NONE ) {
 269                 $cache = MediaWikiServices::getInstance()->getLocalServerObjectCache();
 270                 if ( $cache instanceof EmptyBagOStuff ) {
 271                         if ( is_array( $fallback ) ) {
 272                                 $fallback = $fallback['fallback'] ?? CACHE_NONE;
 273                         }
 274                         $cache = self::getInstance( $fallback );
 275                 }
 276
 277                 return $cache;
 278         }
 279
 280         /**
 281          * Create a new cache object of the specified type.
 282          *
 283          * @since 1.26
 284          * @param string $id A key in $wgWANObjectCaches.
 285          * @return WANObjectCache
 286          * @throws UnexpectedValueException
 287          */
 288         private static function newWANCacheFromId( $id ) {
 289                 global $wgWANObjectCaches, $wgObjectCaches;
 290
 291                 if ( !isset( $wgWANObjectCaches[$id] ) ) {
 292                         throw new UnexpectedValueException(
 293                                 "Cache type \"$id\" requested is not present in \$wgWANObjectCaches." );
 294                 }
 295
 296                 $params = $wgWANObjectCaches[$id];
 297                 if ( !isset( $wgObjectCaches[$params['cacheId']] ) ) {
 298                         throw new UnexpectedValueException(
 299                                 "Cache type \"{$params['cacheId']}\" is not present in \$wgObjectCaches." );
 300                 }
 301                 $params['store'] = $wgObjectCaches[$params['cacheId']];
 302
 303                 return self::newWANCacheFromParams( $params );
 304         }
 305
 306         /**
 307          * Create a new cache object of the specified type.
 308          *
 309          * @since 1.28
 310          * @param array $params
 311          * @return WANObjectCache
 312          * @throws UnexpectedValueException
 313          * @suppress PhanTypeMismatchReturn
 314          * @deprecated since 1.34 Use MediaWikiServices::getMainWANObjectCache
 315          *  instead or use WANObjectCache::__construct directly
 316          */
 317         public static function newWANCacheFromParams( array $params ) {
 318                 wfDeprecated( __METHOD__, '1.34' );
 319                 global $wgCommandLineMode, $wgSecretKey;
 320
 321                 $services = MediaWikiServices::getInstance();
 322                 $params['cache'] = self::newFromParams( $params['store'] );
 323                 $params['logger'] = LoggerFactory::getInstance( $params['loggroup'] ?? 'objectcache' );
 324                 if ( !$wgCommandLineMode ) {
 325                         // Send the statsd data post-send on HTTP requests; avoid in CLI mode (T181385)
 326                         $params['stats'] = $services->getStatsdDataFactory();
 327                         // Let pre-emptive refreshes happen post-send on HTTP requests
 328                         $params['asyncHandler'] = [ DeferredUpdates::class, 'addCallableUpdate' ];
 329                 }
 330                 $params['secret'] = $params['secret'] ?? $wgSecretKey;
 331                 $class = $params['class'];
 332
 333                 return new $class( $params );
 334         }
 335
 336         /**
 337          * Get the main cluster-local cache object.
 338          *
 339          * @since 1.27
 340          * @return BagOStuff
 341          */
 342         public static function getLocalClusterInstance() {
 343                 global $wgMainCacheType;
 344
 345                 return self::getInstance( $wgMainCacheType );
 346         }
 347
 348         /**
 349          * Clear all the cached instances.
 350          */
 351         public static function clear() {
 352                 self::$instances = [];
 353                 self::$wanInstances = [];
 354         }
 355
 356         /**
 357          * Detects which local server cache library is present and returns a configuration for it
 358          * @since 1.32
 359          *
 360          * @return int|string Index to cache in $wgObjectCaches
 361          */
 362         public static function detectLocalServerCache() {
 363                 if ( function_exists( 'apcu_fetch' ) ) {
 364                         // Make sure the APCu methods actually store anything
 365                         if ( PHP_SAPI !== 'cli' || ini_get( 'apc.enable_cli' ) ) {
 366                                 return 'apcu';
 367                         }
 368                 } elseif ( function_exists( 'apc_fetch' ) ) {
 369                         // Make sure the APC methods actually store anything
 370                         if ( PHP_SAPI !== 'cli' || ini_get( 'apc.enable_cli' ) ) {
 371                                 return 'apc';
 372                         }
 373                 } elseif ( function_exists( 'wincache_ucache_get' ) ) {
 374                         return 'wincache';
 375                 }
 376
 377                 return CACHE_NONE;
 378         }
 379 }