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