includes/MediaWikiServices.php

   1 <?php
   2 namespace MediaWiki;
   3
   4 use Config;
   5 use ConfigFactory;
   6 use EventRelayerGroup;
   7 use GenderCache;
   8 use GlobalVarConfig;
   9 use Hooks;
  10 use LBFactory;
  11 use LinkCache;
  12 use Liuggio\StatsdClient\Factory\StatsdDataFactory;
  13 use LoadBalancer;
  14 use MediaWiki\Services\SalvageableService;
  15 use MediaWiki\Services\ServiceContainer;
  16 use MWException;
  17 use ObjectCache;
  18 use ResourceLoader;
  19 use SearchEngine;
  20 use SearchEngineConfig;
  21 use SearchEngineFactory;
  22 use SiteLookup;
  23 use SiteStore;
  24 use WatchedItemStore;
  25 use SkinFactory;
  26 use TitleFormatter;
  27 use TitleParser;
  28 use MediaWiki\Interwiki\InterwikiLookup;
  29
  30 /**
  31  * Service locator for MediaWiki core services.
  32  *
  33  * This program is free software; you can redistribute it and/or modify
  34  * it under the terms of the GNU General Public License as published by
  35  * the Free Software Foundation; either version 2 of the License, or
  36  * (at your option) any later version.
  37  *
  38  * This program is distributed in the hope that it will be useful,
  39  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  40  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  41  * GNU General Public License for more details.
  42  *
  43  * You should have received a copy of the GNU General Public License along
  44  * with this program; if not, write to the Free Software Foundation, Inc.,
  45  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  46  * http://www.gnu.org/copyleft/gpl.html
  47  *
  48  * @file
  49  *
  50  * @since 1.27
  51  */
  52
  53 /**
  54  * MediaWikiServices is the service locator for the application scope of MediaWiki.
  55  * Its implemented as a simple configurable DI container.
  56  * MediaWikiServices acts as a top level factory/registry for top level services, and builds
  57  * the network of service objects that defines MediaWiki's application logic.
  58  * It acts as an entry point to MediaWiki's dependency injection mechanism.
  59  *
  60  * Services are defined in the "wiring" array passed to the constructor,
  61  * or by calling defineService().
  62  *
  63  * @see docs/injection.txt for an overview of using dependency injection in the
  64  *      MediaWiki code base.
  65  */
  66 class MediaWikiServices extends ServiceContainer {
  67
  68         /**
  69          * @var MediaWikiServices|null
  70          */
  71         private static $instance = null;
  72
  73         /**
  74          * Returns the global default instance of the top level service locator.
  75          *
  76          * @since 1.27
  77          *
  78          * The default instance is initialized using the service instantiator functions
  79          * defined in ServiceWiring.php.
  80          *
  81          * @note This should only be called by static functions! The instance returned here
  82          * should not be passed around! Objects that need access to a service should have
  83          * that service injected into the constructor, never a service locator!
  84          *
  85          * @return MediaWikiServices
  86          */
  87         public static function getInstance() {
  88                 if ( self::$instance === null ) {
  89                         // NOTE: constructing GlobalVarConfig here is not particularly pretty,
  90                         // but some information from the global scope has to be injected here,
  91                         // even if it's just a file name or database credentials to load
  92                         // configuration from.
  93                         $bootstrapConfig = new GlobalVarConfig();
  94                         self::$instance = self::newInstance( $bootstrapConfig, 'load' );
  95                 }
  96
  97                 return self::$instance;
  98         }
  99
 100         /**
 101          * Replaces the global MediaWikiServices instance.
 102          *
 103          * @since 1.28
 104          *
 105          * @note This is for use in PHPUnit tests only!
 106          *
 107          * @throws MWException if called outside of PHPUnit tests.
 108          *
 109          * @param MediaWikiServices $services The new MediaWikiServices object.
 110          *
 111          * @return MediaWikiServices The old MediaWikiServices object, so it can be restored later.
 112          */
 113         public static function forceGlobalInstance( MediaWikiServices $services ) {
 114                 if ( !defined( 'MW_PHPUNIT_TEST' ) ) {
 115                         throw new MWException( __METHOD__ . ' must not be used outside unit tests.' );
 116                 }
 117
 118                 $old = self::getInstance();
 119                 self::$instance = $services;
 120
 121                 return $old;
 122         }
 123
 124         /**
 125          * Creates a new instance of MediaWikiServices and sets it as the global default
 126          * instance. getInstance() will return a different MediaWikiServices object
 127          * after every call to resetGlobalInstance().
 128          *
 129          * @since 1.28
 130          *
 131          * @warning This should not be used during normal operation. It is intended for use
 132          * when the configuration has changed significantly since bootstrap time, e.g.
 133          * during the installation process or during testing.
 134          *
 135          * @warning Calling resetGlobalInstance() may leave the application in an inconsistent
 136          * state. Calling this is only safe under the ASSUMPTION that NO REFERENCE to
 137          * any of the services managed by MediaWikiServices exist. If any service objects
 138          * managed by the old MediaWikiServices instance remain in use, they may INTERFERE
 139          * with the operation of the services managed by the new MediaWikiServices.
 140          * Operating with a mix of services created by the old and the new
 141          * MediaWikiServices instance may lead to INCONSISTENCIES and even DATA LOSS!
 142          * Any class implementing LAZY LOADING is especially prone to this problem,
 143          * since instances would typically retain a reference to a storage layer service.
 144          *
 145          * @see forceGlobalInstance()
 146          * @see resetGlobalInstance()
 147          * @see resetBetweenTest()
 148          *
 149          * @param Config|null $bootstrapConfig The Config object to be registered as the
 150          *        'BootstrapConfig' service. This has to contain at least the information
 151          *        needed to set up the 'ConfigFactory' service. If not given, the bootstrap
 152          *        config of the old instance of MediaWikiServices will be re-used. If there
 153          *        was no previous instance, a new GlobalVarConfig object will be used to
 154          *        bootstrap the services.
 155          *
 156          * @param string $quick Set this to "quick" to allow expensive resources to be re-used.
 157          * See SalvageableService for details.
 158          *
 159          * @throws MWException If called after MW_SERVICE_BOOTSTRAP_COMPLETE has been defined in
 160          *         Setup.php (unless MW_PHPUNIT_TEST or MEDIAWIKI_INSTALL or RUN_MAINTENANCE_IF_MAIN
 161          *          is defined).
 162          */
 163         public static function resetGlobalInstance( Config $bootstrapConfig = null, $quick = '' ) {
 164                 if ( self::$instance === null ) {
 165                         // no global instance yet, nothing to reset
 166                         return;
 167                 }
 168
 169                 self::failIfResetNotAllowed( __METHOD__ );
 170
 171                 if ( $bootstrapConfig === null ) {
 172                         $bootstrapConfig = self::$instance->getBootstrapConfig();
 173                 }
 174
 175                 $oldInstance = self::$instance;
 176
 177                 self::$instance = self::newInstance( $bootstrapConfig );
 178                 self::$instance->importWiring( $oldInstance, [ 'BootstrapConfig' ] );
 179
 180                 if ( $quick === 'quick' ) {
 181                         self::$instance->salvage( $oldInstance );
 182                 } else {
 183                         $oldInstance->destroy();
 184                 }
 185
 186         }
 187
 188         /**
 189          * Salvages the state of any salvageable service instances in $other.
 190          *
 191          * @note $other will have been destroyed when salvage() returns.
 192          *
 193          * @param MediaWikiServices $other
 194          */
 195         private function salvage( self $other ) {
 196                 foreach ( $this->getServiceNames() as $name ) {
 197                         $oldService = $other->peekService( $name );
 198
 199                         if ( $oldService instanceof SalvageableService ) {
 200                                 /** @var SalvageableService $newService */
 201                                 $newService = $this->getService( $name );
 202                                 $newService->salvage( $oldService );
 203                         }
 204                 }
 205
 206                 $other->destroy();
 207         }
 208
 209         /**
 210          * Creates a new MediaWikiServices instance and initializes it according to the
 211          * given $bootstrapConfig. In particular, all wiring files defined in the
 212          * ServiceWiringFiles setting are loaded, and the MediaWikiServices hook is called.
 213          *
 214          * @param Config|null $bootstrapConfig The Config object to be registered as the
 215          *        'BootstrapConfig' service.
 216          *
 217          * @param string $loadWiring set this to 'load' to load the wiring files specified
 218          *        in the 'ServiceWiringFiles' setting in $bootstrapConfig.
 219          *
 220          * @return MediaWikiServices
 221          * @throws MWException
 222          * @throws \FatalError
 223          */
 224         private static function newInstance( Config $bootstrapConfig, $loadWiring = '' ) {
 225                 $instance = new self( $bootstrapConfig );
 226
 227                 // Load the default wiring from the specified files.
 228                 if ( $loadWiring === 'load' ) {
 229                         $wiringFiles = $bootstrapConfig->get( 'ServiceWiringFiles' );
 230                         $instance->loadWiringFiles( $wiringFiles );
 231                 }
 232
 233                 // Provide a traditional hook point to allow extensions to configure services.
 234                 Hooks::run( 'MediaWikiServices', [ $instance ] );
 235
 236                 return $instance;
 237         }
 238
 239         /**
 240          * Disables all storage layer services. After calling this, any attempt to access the
 241          * storage layer will result in an error. Use resetGlobalInstance() to restore normal
 242          * operation.
 243          *
 244          * @since 1.28
 245          *
 246          * @warning This is intended for extreme situations only and should never be used
 247          * while serving normal web requests. Legitimate use cases for this method include
 248          * the installation process. Test fixtures may also use this, if the fixture relies
 249          * on globalState.
 250          *
 251          * @see resetGlobalInstance()
 252          * @see resetChildProcessServices()
 253          */
 254         public static function disableStorageBackend() {
 255                 // TODO: also disable some Caches, JobQueues, etc
 256                 $destroy = [ 'DBLoadBalancer', 'DBLoadBalancerFactory' ];
 257                 $services = self::getInstance();
 258
 259                 foreach ( $destroy as $name ) {
 260                         $services->disableService( $name );
 261                 }
 262
 263                 ObjectCache::clear();
 264         }
 265
 266         /**
 267          * Resets any services that may have become stale after a child process
 268          * returns from after pcntl_fork(). It's also safe, but generally unnecessary,
 269          * to call this method from the parent process.
 270          *
 271          * @since 1.28
 272          *
 273          * @note This is intended for use in the context of process forking only!
 274          *
 275          * @see resetGlobalInstance()
 276          * @see disableStorageBackend()
 277          */
 278         public static function resetChildProcessServices() {
 279                 // NOTE: for now, just reset everything. Since we don't know the interdependencies
 280                 // between services, we can't do this more selectively at this time.
 281                 self::resetGlobalInstance();
 282
 283                 // Child, reseed because there is no bug in PHP:
 284                 // http://bugs.php.net/bug.php?id=42465
 285                 mt_srand( getmypid() );
 286         }
 287
 288         /**
 289          * Resets the given service for testing purposes.
 290          *
 291          * @since 1.28
 292          *
 293          * @warning This is generally unsafe! Other services may still retain references
 294          * to the stale service instance, leading to failures and inconsistencies. Subclasses
 295          * may use this method to reset specific services under specific instances, but
 296          * it should not be exposed to application logic.
 297          *
 298          * @note With proper dependency injection used throughout the codebase, this method
 299          * should not be needed. It is provided to allow tests that pollute global service
 300          * instances to clean up.
 301          *
 302          * @param string $name
 303          * @param bool $destroy Whether the service instance should be destroyed if it exists.
 304          *        When set to false, any existing service instance will effectively be detached
 305          *        from the container.
 306          *
 307          * @throws MWException if called outside of PHPUnit tests.
 308          */
 309         public function resetServiceForTesting( $name, $destroy = true ) {
 310                 if ( !defined( 'MW_PHPUNIT_TEST' ) && !defined( 'MW_PARSER_TEST' ) ) {
 311                         throw new MWException( 'resetServiceForTesting() must not be used outside unit tests.' );
 312                 }
 313
 314                 $this->resetService( $name, $destroy );
 315         }
 316
 317         /**
 318          * Convenience method that throws an exception unless it is called during a phase in which
 319          * resetting of global services is allowed. In general, services should not be reset
 320          * individually, since that may introduce inconsistencies.
 321          *
 322          * @since 1.28
 323          *
 324          * This method will throw an exception if:
 325          *
 326          * - self::$resetInProgress is false (to allow all services to be reset together
 327          *   via resetGlobalInstance)
 328          * - and MEDIAWIKI_INSTALL is not defined (to allow services to be reset during installation)
 329          * - and MW_PHPUNIT_TEST is not defined (to allow services to be reset during testing)
 330          *
 331          * This method is intended to be used to safeguard against accidentally resetting
 332          * global service instances that are not yet managed by MediaWikiServices. It is
 333          * defined here in the MediaWikiServices services class to have a central place
 334          * for managing service bootstrapping and resetting.
 335          *
 336          * @param string $method the name of the caller method, as given by __METHOD__.
 337          *
 338          * @throws MWException if called outside bootstrap mode.
 339          *
 340          * @see resetGlobalInstance()
 341          * @see forceGlobalInstance()
 342          * @see disableStorageBackend()
 343          */
 344         public static function failIfResetNotAllowed( $method ) {
 345                 if ( !defined( 'MW_PHPUNIT_TEST' )
 346                         && !defined( 'MW_PARSER_TEST' )
 347                         && !defined( 'MEDIAWIKI_INSTALL' )
 348                         && !defined( 'RUN_MAINTENANCE_IF_MAIN' )
 349                         && defined( 'MW_SERVICE_BOOTSTRAP_COMPLETE' )
 350                 ) {
 351                         throw new MWException( $method . ' may only be called during bootstrapping and unit tests!' );
 352                 }
 353         }
 354
 355         /**
 356          * @param Config $config The Config object to be registered as the 'BootstrapConfig' service.
 357          *        This has to contain at least the information needed to set up the 'ConfigFactory'
 358          *        service.
 359          */
 360         public function __construct( Config $config ) {
 361                 parent::__construct();
 362
 363                 // Register the given Config object as the bootstrap config service.
 364                 $this->defineService( 'BootstrapConfig', function() use ( $config ) {
 365                         return $config;
 366                 } );
 367         }
 368
 369         // CONVENIENCE GETTERS ////////////////////////////////////////////////////
 370
 371         /**
 372          * Returns the Config object containing the bootstrap configuration.
 373          * Bootstrap configuration would typically include database credentials
 374          * and other information that may be needed before the ConfigFactory
 375          * service can be instantiated.
 376          *
 377          * @note This should only be used during bootstrapping, in particular
 378          * when creating the MainConfig service. Application logic should
 379          * use getMainConfig() to get a Config instances.
 380          *
 381          * @since 1.27
 382          * @return Config
 383          */
 384         public function getBootstrapConfig() {
 385                 return $this->getService( 'BootstrapConfig' );
 386         }
 387
 388         /**
 389          * @since 1.27
 390          * @return ConfigFactory
 391          */
 392         public function getConfigFactory() {
 393                 return $this->getService( 'ConfigFactory' );
 394         }
 395
 396         /**
 397          * Returns the Config object that provides configuration for MediaWiki core.
 398          * This may or may not be the same object that is returned by getBootstrapConfig().
 399          *
 400          * @since 1.27
 401          * @return Config
 402          */
 403         public function getMainConfig() {
 404                 return $this->getService( 'MainConfig' );
 405         }
 406
 407         /**
 408          * @since 1.27
 409          * @return SiteLookup
 410          */
 411         public function getSiteLookup() {
 412                 return $this->getService( 'SiteLookup' );
 413         }
 414
 415         /**
 416          * @since 1.27
 417          * @return SiteStore
 418          */
 419         public function getSiteStore() {
 420                 return $this->getService( 'SiteStore' );
 421         }
 422
 423         /**
 424          * @since 1.28
 425          * @return InterwikiLookup
 426          */
 427         public function getInterwikiLookup() {
 428                 return $this->getService( 'InterwikiLookup' );
 429         }
 430
 431         /**
 432          * @since 1.27
 433          * @return StatsdDataFactory
 434          */
 435         public function getStatsdDataFactory() {
 436                 return $this->getService( 'StatsdDataFactory' );
 437         }
 438
 439         /**
 440          * @since 1.27
 441          * @return EventRelayerGroup
 442          */
 443         public function getEventRelayerGroup() {
 444                 return $this->getService( 'EventRelayerGroup' );
 445         }
 446
 447         /**
 448          * @since 1.27
 449          * @return SearchEngine
 450          */
 451         public function newSearchEngine() {
 452                 // New engine object every time, since they keep state
 453                 return $this->getService( 'SearchEngineFactory' )->create();
 454         }
 455
 456         /**
 457          * @since 1.27
 458          * @return SearchEngineFactory
 459          */
 460         public function getSearchEngineFactory() {
 461                 return $this->getService( 'SearchEngineFactory' );
 462         }
 463
 464         /**
 465          * @since 1.27
 466          * @return SearchEngineConfig
 467          */
 468         public function getSearchEngineConfig() {
 469                 return $this->getService( 'SearchEngineConfig' );
 470         }
 471
 472         /**
 473          * @since 1.27
 474          * @return SkinFactory
 475          */
 476         public function getSkinFactory() {
 477                 return $this->getService( 'SkinFactory' );
 478         }
 479
 480         /**
 481          * @since 1.28
 482          * @return LBFactory
 483          */
 484         public function getDBLoadBalancerFactory() {
 485                 return $this->getService( 'DBLoadBalancerFactory' );
 486         }
 487
 488         /**
 489          * @since 1.28
 490          * @return LoadBalancer The main DB load balancer for the local wiki.
 491          */
 492         public function getDBLoadBalancer() {
 493                 return $this->getService( 'DBLoadBalancer' );
 494         }
 495
 496         /**
 497          * @since 1.28
 498          * @return WatchedItemStore
 499          */
 500         public function getWatchedItemStore() {
 501                 return $this->getService( 'WatchedItemStore' );
 502         }
 503
 504         /**
 505          * @since 1.28
 506          * @return GenderCache
 507          */
 508         public function getGenderCache() {
 509                 return $this->getService( 'GenderCache' );
 510         }
 511
 512         /**
 513          * @since 1.28
 514          * @return LinkCache
 515          */
 516         public function getLinkCache() {
 517                 return $this->getService( 'LinkCache' );
 518         }
 519
 520         /**
 521          * @since 1.28
 522          * @return TitleFormatter
 523          */
 524         public function getTitleFormatter() {
 525                 return $this->getService( 'TitleFormatter' );
 526         }
 527
 528         /**
 529          * @since 1.28
 530          * @return TitleParser
 531          */
 532         public function getTitleParser() {
 533                 return $this->getService( 'TitleParser' );
 534         }
 535
 536         ///////////////////////////////////////////////////////////////////////////
 537         // NOTE: When adding a service getter here, don't forget to add a test
 538         // case for it in MediaWikiServicesTest::provideGetters() and in
 539         // MediaWikiServicesTest::provideGetService()!
 540         ///////////////////////////////////////////////////////////////////////////
 541
 542 }