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          */
  95         public static function getWANInstance( $id ) {
  96                 if ( !isset( self::$wanInstances[$id] ) ) {
  97                         self::$wanInstances[$id] = self::newWANCacheFromId( $id );
  98                 }
  99
 100                 return self::$wanInstances[$id];
 101         }
 102
 103         /**
 104          * Create a new cache object of the specified type.
 105          *
 106          * @param string $id A key in $wgObjectCaches.
 107          * @return BagOStuff
 108          * @throws InvalidArgumentException
 109          */
 110         private static function newFromId( $id ) {
 111                 global $wgObjectCaches;
 112
 113                 if ( !isset( $wgObjectCaches[$id] ) ) {
 114                         // Always recognize these ones
 115                         if ( $id === CACHE_NONE ) {
 116                                 return new EmptyBagOStuff();
 117                         } elseif ( $id === 'hash' ) {
 118                                 return new HashBagOStuff();
 119                         }
 120
 121                         throw new InvalidArgumentException( "Invalid object cache type \"$id\" requested. " .
 122                                 "It is not present in \$wgObjectCaches." );
 123                 }
 124
 125                 return self::newFromParams( $wgObjectCaches[$id] );
 126         }
 127
 128         /**
 129          * Get the default keyspace for this wiki.
 130          *
 131          * This is either the value of the `CachePrefix` configuration variable,
 132          * or (if the former is unset) the `DBname` configuration variable, with
 133          * `DBprefix` (if defined).
 134          *
 135          * @return string
 136          */
 137         private static function getDefaultKeyspace() {
 138                 global $wgCachePrefix;
 139
 140                 $keyspace = $wgCachePrefix;
 141                 if ( is_string( $keyspace ) && $keyspace !== '' ) {
 142                         return $keyspace;
 143                 }
 144
 145                 return WikiMap::getCurrentWikiDbDomain()->getId();
 146         }
 147
 148         /**
 149          * Create a new cache object from parameters.
 150          *
 151          * @param array $params Must have 'factory' or 'class' property.
 152          *  - factory: Callback passed $params that returns BagOStuff.
 153          *  - class: BagOStuff subclass constructed with $params.
 154          *  - loggroup: Alias to set 'logger' key with LoggerFactory group.
 155          *  - .. Other parameters passed to factory or class.
 156          * @return BagOStuff
 157          * @throws InvalidArgumentException
 158          */
 159         public static function newFromParams( $params ) {
 160                 $params['logger'] = LoggerFactory::getInstance( $params['loggroup'] ?? 'objectcache' );
 161                 if ( !isset( $params['keyspace'] ) ) {
 162                         $params['keyspace'] = self::getDefaultKeyspace();
 163                 }
 164                 if ( isset( $params['factory'] ) ) {
 165                         return call_user_func( $params['factory'], $params );
 166                 } elseif ( isset( $params['class'] ) ) {
 167                         $class = $params['class'];
 168                         // Automatically set the 'async' update handler
 169                         $params['asyncHandler'] = $params['asyncHandler']
 170                                 ?? [ DeferredUpdates::class, 'addCallableUpdate' ];
 171                         // Enable reportDupes by default
 172                         $params['reportDupes'] = $params['reportDupes'] ?? true;
 173                         // Do b/c logic for SqlBagOStuff
 174                         if ( is_a( $class, SqlBagOStuff::class, true ) ) {
 175                                 if ( isset( $params['server'] ) && !isset( $params['servers'] ) ) {
 176                                         $params['servers'] = [ $params['server'] ];
 177                                         unset( $params['server'] );
 178                                 }
 179                                 // In the past it was not required to set 'dbDirectory' in $wgObjectCaches
 180                                 if ( isset( $params['servers'] ) ) {
 181                                         foreach ( $params['servers'] as &$server ) {
 182                                                 if ( $server['type'] === 'sqlite' && !isset( $server['dbDirectory'] ) ) {
 183                                                         $server['dbDirectory'] = MediaWikiServices::getInstance()
 184                                                                 ->getMainConfig()->get( 'SQLiteDataDir' );
 185                                                 }
 186                                         }
 187                                 }
 188                         }
 189
 190                         // Do b/c logic for MemcachedBagOStuff
 191                         if ( is_subclass_of( $class, MemcachedBagOStuff::class ) ) {
 192                                 if ( !isset( $params['servers'] ) ) {
 193                                         $params['servers'] = $GLOBALS['wgMemCachedServers'];
 194                                 }
 195                                 if ( !isset( $params['persistent'] ) ) {
 196                                         $params['persistent'] = $GLOBALS['wgMemCachedPersistent'];
 197                                 }
 198                                 if ( !isset( $params['timeout'] ) ) {
 199                                         $params['timeout'] = $GLOBALS['wgMemCachedTimeout'];
 200                                 }
 201                         }
 202                         return new $class( $params );
 203                 } else {
 204                         throw new InvalidArgumentException( "The definition of cache type \""
 205                                 . print_r( $params, true ) . "\" lacks both "
 206                                 . "factory and class parameters." );
 207                 }
 208         }
 209
 210         /**
 211          * Factory function for CACHE_ANYTHING (referenced from DefaultSettings.php)
 212          *
 213          * CACHE_ANYTHING means that stuff has to be cached, not caching is not an option.
 214          * If a caching method is configured for any of the main caches ($wgMainCacheType,
 215          * $wgMessageCacheType, $wgParserCacheType), then CACHE_ANYTHING will effectively
 216          * be an alias to the configured cache choice for that.
 217          * If no cache choice is configured (by default $wgMainCacheType is CACHE_NONE),
 218          * then CACHE_ANYTHING will forward to CACHE_DB.
 219          *
 220          * @param array $params
 221          * @return BagOStuff
 222          */
 223         public static function newAnything( $params ) {
 224                 global $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType;
 225                 $candidates = [ $wgMainCacheType, $wgMessageCacheType, $wgParserCacheType ];
 226                 foreach ( $candidates as $candidate ) {
 227                         if ( $candidate !== CACHE_NONE && $candidate !== CACHE_ANYTHING ) {
 228                                 $cache = self::getInstance( $candidate );
 229                                 // CACHE_ACCEL might default to nothing if no APCu
 230                                 // See includes/ServiceWiring.php
 231                                 if ( !( $cache instanceof EmptyBagOStuff ) ) {
 232                                         return $cache;
 233                                 }
 234                         }
 235                 }
 236
 237                 if ( MediaWikiServices::getInstance()->isServiceDisabled( 'DBLoadBalancer' ) ) {
 238                         // The LoadBalancer is disabled, probably because
 239                         // MediaWikiServices::disableStorageBackend was called.
 240                         $candidate = CACHE_NONE;
 241                 } else {
 242                         $candidate = CACHE_DB;
 243                 }
 244
 245                 return self::getInstance( $candidate );
 246         }
 247
 248         /**
 249          * Factory function for CACHE_ACCEL (referenced from DefaultSettings.php)
 250          *
 251          * This will look for any APC or APCu style server-local cache.
 252          * A fallback cache can be specified if none is found.
 253          *
 254          *     // Direct calls
 255          *     ObjectCache::getLocalServerInstance( $fallbackType );
 256          *
 257          *     // From $wgObjectCaches via newFromParams()
 258          *     ObjectCache::getLocalServerInstance( [ 'fallback' => $fallbackType ] );
 259          *
 260          * @param int|string|array $fallback Fallback cache or parameter map with 'fallback'
 261          * @return BagOStuff
 262          * @throws InvalidArgumentException
 263          * @since 1.27
 264          */
 265         public static function getLocalServerInstance( $fallback = CACHE_NONE ) {
 266                 $cache = MediaWikiServices::getInstance()->getLocalServerObjectCache();
 267                 if ( $cache instanceof EmptyBagOStuff ) {
 268                         if ( is_array( $fallback ) ) {
 269                                 $fallback = $fallback['fallback'] ?? CACHE_NONE;
 270                         }
 271                         $cache = self::getInstance( $fallback );
 272                 }
 273
 274                 return $cache;
 275         }
 276
 277         /**
 278          * Create a new cache object of the specified type.
 279          *
 280          * @since 1.26
 281          * @param string $id A key in $wgWANObjectCaches.
 282          * @return WANObjectCache
 283          * @throws UnexpectedValueException
 284          */
 285         private static function newWANCacheFromId( $id ) {
 286                 global $wgWANObjectCaches, $wgObjectCaches;
 287
 288                 if ( !isset( $wgWANObjectCaches[$id] ) ) {
 289                         throw new UnexpectedValueException(
 290                                 "Cache type \"$id\" requested is not present in \$wgWANObjectCaches." );
 291                 }
 292
 293                 $params = $wgWANObjectCaches[$id];
 294                 if ( !isset( $wgObjectCaches[$params['cacheId']] ) ) {
 295                         throw new UnexpectedValueException(
 296                                 "Cache type \"{$params['cacheId']}\" is not present in \$wgObjectCaches." );
 297                 }
 298                 $params['store'] = $wgObjectCaches[$params['cacheId']];
 299
 300                 return self::newWANCacheFromParams( $params );
 301         }
 302
 303         /**
 304          * Create a new cache object of the specified type.
 305          *
 306          * @since 1.28
 307          * @param array $params
 308          * @return WANObjectCache
 309          * @throws UnexpectedValueException
 310          * @suppress PhanTypeMismatchReturn
 311          */
 312         public static function newWANCacheFromParams( array $params ) {
 313                 global $wgCommandLineMode, $wgSecretKey;
 314
 315                 $services = MediaWikiServices::getInstance();
 316                 $params['cache'] = self::newFromParams( $params['store'] );
 317                 $params['logger'] = LoggerFactory::getInstance( $params['loggroup'] ?? 'objectcache' );
 318                 if ( !$wgCommandLineMode ) {
 319                         // Send the statsd data post-send on HTTP requests; avoid in CLI mode (T181385)
 320                         $params['stats'] = $services->getStatsdDataFactory();
 321                         // Let pre-emptive refreshes happen post-send on HTTP requests
 322                         $params['asyncHandler'] = [ DeferredUpdates::class, 'addCallableUpdate' ];
 323                 }
 324                 $params['secret'] = $params['secret'] ?? $wgSecretKey;
 325                 $class = $params['class'];
 326
 327                 return new $class( $params );
 328         }
 329
 330         /**
 331          * Get the main cluster-local cache object.
 332          *
 333          * @since 1.27
 334          * @return BagOStuff
 335          */
 336         public static function getLocalClusterInstance() {
 337                 global $wgMainCacheType;
 338
 339                 return self::getInstance( $wgMainCacheType );
 340         }
 341
 342         /**
 343          * Clear all the cached instances.
 344          */
 345         public static function clear() {
 346                 self::$instances = [];
 347                 self::$wanInstances = [];
 348         }
 349
 350         /**
 351          * Detects which local server cache library is present and returns a configuration for it
 352          * @since 1.32
 353          *
 354          * @return int|string Index to cache in $wgObjectCaches
 355          */
 356         public static function detectLocalServerCache() {
 357                 if ( function_exists( 'apcu_fetch' ) ) {
 358                         // Make sure the APCu methods actually store anything
 359                         if ( PHP_SAPI !== 'cli' || ini_get( 'apc.enable_cli' ) ) {
 360                                 return 'apcu';
 361                         }
 362                 } elseif ( function_exists( 'apc_fetch' ) ) {
 363                         // Make sure the APC methods actually store anything
 364                         if ( PHP_SAPI !== 'cli' || ini_get( 'apc.enable_cli' ) ) {
 365                                 return 'apc';
 366                         }
 367                 } elseif ( function_exists( 'wincache_ucache_get' ) ) {
 368                         return 'wincache';
 369                 }
 370
 371                 return CACHE_NONE;
 372         }
 373 }