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\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( $bootstrapConfig );
  92                 }
  93
  94                 return self::$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 resetGlobalServiceLocator().
 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 resetGlobalServiceLocator() 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          * @throws MWException If called after MW_SERVICE_BOOTSTRAP_COMPLETE has been defined in
 154          *         Setup.php (unless MW_PHPUNIT_TEST or MEDIAWIKI_INSTALL or RUN_MAINTENANCE_IF_MAIN
 155          *          is defined).
 156          */
 157         public static function resetGlobalInstance( Config $bootstrapConfig = null ) {
 158                 if ( self::$instance === null ) {
 159                         // no global instance yet, nothing to reset
 160                         return;
 161                 }
 162
 163                 self::failIfResetNotAllowed( __METHOD__ );
 164
 165                 if ( $bootstrapConfig === null ) {
 166                         $bootstrapConfig = self::$instance->getBootstrapConfig();
 167                 }
 168
 169                 self::$instance->destroy();
 170
 171                 self::$instance = self::newInstance( $bootstrapConfig );
 172         }
 173
 174         /**
 175          * Creates a new MediaWikiServices instance and initializes it according to the
 176          * given $bootstrapConfig. In particular, all wiring files defined in the
 177          * ServiceWiringFiles setting are loaded, and the MediaWikiServices hook is called.
 178          *
 179          * @param Config|null $bootstrapConfig The Config object to be registered as the
 180          *        'BootstrapConfig' service. This has to contain at least the information
 181          *        needed to set up the 'ConfigFactory' service. If not provided, any call
 182          *        to getBootstrapConfig(), getConfigFactory, or getMainConfig will fail.
 183          *        A MediaWikiServices instance without access to configuration is called
 184          *        "primordial".
 185          *
 186          * @return MediaWikiServices
 187          * @throws MWException
 188          */
 189         private static function newInstance( Config $bootstrapConfig ) {
 190                 $instance = new self( $bootstrapConfig );
 191
 192                 // Load the default wiring from the specified files.
 193                 $wiringFiles = $bootstrapConfig->get( 'ServiceWiringFiles' );
 194                 $instance->loadWiringFiles( $wiringFiles );
 195
 196                 // Provide a traditional hook point to allow extensions to configure services.
 197                 Hooks::run( 'MediaWikiServices', [ $instance ] );
 198
 199                 return $instance;
 200         }
 201
 202         /**
 203          * Disables all storage layer services. After calling this, any attempt to access the
 204          * storage layer will result in an error. Use resetGlobalInstance() to restore normal
 205          * operation.
 206          *
 207          * @since 1.28
 208          *
 209          * @warning This is intended for extreme situations only and should never be used
 210          * while serving normal web requests. Legitimate use cases for this method include
 211          * the installation process. Test fixtures may also use this, if the fixture relies
 212          * on globalState.
 213          *
 214          * @see resetGlobalInstance()
 215          * @see resetChildProcessServices()
 216          */
 217         public static function disableStorageBackend() {
 218                 // TODO: also disable some Caches, JobQueues, etc
 219                 $destroy = [ 'DBLoadBalancer', 'DBLoadBalancerFactory' ];
 220                 $services = self::getInstance();
 221
 222                 foreach ( $destroy as $name ) {
 223                         $services->disableService( $name );
 224                 }
 225         }
 226
 227         /**
 228          * Resets any services that may have become stale after a child process
 229          * returns from after pcntl_fork(). It's also safe, but generally unnecessary,
 230          * to call this method from the parent process.
 231          *
 232          * @since 1.28
 233          *
 234          * @note This is intended for use in the context of process forking only!
 235          *
 236          * @see resetGlobalInstance()
 237          * @see disableStorageBackend()
 238          */
 239         public static function resetChildProcessServices() {
 240                 // NOTE: for now, just reset everything. Since we don't know the interdependencies
 241                 // between services, we can't do this more selectively at this time.
 242                 self::resetGlobalInstance();
 243
 244                 // Child, reseed because there is no bug in PHP:
 245                 // http://bugs.php.net/bug.php?id=42465
 246                 mt_srand( getmypid() );
 247         }
 248
 249         /**
 250          * Resets the given service for testing purposes.
 251          *
 252          * @since 1.28
 253          *
 254          * @warning This is generally unsafe! Other services may still retain references
 255          * to the stale service instance, leading to failures and inconsistencies. Subclasses
 256          * may use this method to reset specific services under specific instances, but
 257          * it should not be exposed to application logic.
 258          *
 259          * @note With proper dependency injection used throughout the codebase, this method
 260          * should not be needed. It is provided to allow tests that pollute global service
 261          * instances to clean up.
 262          *
 263          * @param string $name
 264          * @param string $destroy Whether the service instance should be destroyed if it exists.
 265          *        When set to false, any existing service instance will effectively be detached
 266          *        from the container.
 267          *
 268          * @throws MWException if called outside of PHPUnit tests.
 269          */
 270         public function resetServiceForTesting( $name, $destroy = true ) {
 271                 if ( !defined( 'MW_PHPUNIT_TEST' ) && !defined( 'MW_PARSER_TEST' ) ) {
 272                         throw new MWException( 'resetServiceForTesting() must not be used outside unit tests.' );
 273                 }
 274
 275                 $this->resetService( $name, $destroy );
 276         }
 277
 278         /**
 279          * Convenience method that throws an exception unless it is called during a phase in which
 280          * resetting of global services is allowed. In general, services should not be reset
 281          * individually, since that may introduce inconsistencies.
 282          *
 283          * @since 1.28
 284          *
 285          * This method will throw an exception if:
 286          *
 287          * - self::$resetInProgress is false (to allow all services to be reset together
 288          *   via resetGlobalInstance)
 289          * - and MEDIAWIKI_INSTALL is not defined (to allow services to be reset during installation)
 290          * - and MW_PHPUNIT_TEST is not defined (to allow services to be reset during testing)
 291          *
 292          * This method is intended to be used to safeguard against accidentally resetting
 293          * global service instances that are not yet managed by MediaWikiServices. It is
 294          * defined here in the MediaWikiServices services class to have a central place
 295          * for managing service bootstrapping and resetting.
 296          *
 297          * @param string $method the name of the caller method, as given by __METHOD__.
 298          *
 299          * @throws MWException if called outside bootstrap mode.
 300          *
 301          * @see resetGlobalInstance()
 302          * @see forceGlobalInstance()
 303          * @see disableStorageBackend()
 304          */
 305         public static function failIfResetNotAllowed( $method ) {
 306                 if ( !defined( 'MW_PHPUNIT_TEST' )
 307                         && !defined( 'MW_PARSER_TEST' )
 308                         && !defined( 'MEDIAWIKI_INSTALL' )
 309                         && !defined( 'RUN_MAINTENANCE_IF_MAIN' )
 310                         && defined( 'MW_SERVICE_BOOTSTRAP_COMPLETE' )
 311                 ) {
 312                         throw new MWException( $method . ' may only be called during bootstrapping and unit tests!' );
 313                 }
 314         }
 315
 316         /**
 317          * @param Config $config The Config object to be registered as the 'BootstrapConfig' service.
 318          *        This has to contain at least the information needed to set up the 'ConfigFactory'
 319          *        service.
 320          */
 321         public function __construct( Config $config ) {
 322                 parent::__construct();
 323
 324                 // Register the given Config object as the bootstrap config service.
 325                 $this->defineService( 'BootstrapConfig', function() use ( $config ) {
 326                         return $config;
 327                 } );
 328         }
 329
 330         // CONVENIENCE GETTERS ////////////////////////////////////////////////////
 331
 332         /**
 333          * Returns the Config object containing the bootstrap configuration.
 334          * Bootstrap configuration would typically include database credentials
 335          * and other information that may be needed before the ConfigFactory
 336          * service can be instantiated.
 337          *
 338          * @note This should only be used during bootstrapping, in particular
 339          * when creating the MainConfig service. Application logic should
 340          * use getMainConfig() to get a Config instances.
 341          *
 342          * @since 1.27
 343          * @return Config
 344          */
 345         public function getBootstrapConfig() {
 346                 return $this->getService( 'BootstrapConfig' );
 347         }
 348
 349         /**
 350          * @since 1.27
 351          * @return ConfigFactory
 352          */
 353         public function getConfigFactory() {
 354                 return $this->getService( 'ConfigFactory' );
 355         }
 356
 357         /**
 358          * Returns the Config object that provides configuration for MediaWiki core.
 359          * This may or may not be the same object that is returned by getBootstrapConfig().
 360          *
 361          * @since 1.27
 362          * @return Config
 363          */
 364         public function getMainConfig() {
 365                 return $this->getService( 'MainConfig' );
 366         }
 367
 368         /**
 369          * @since 1.27
 370          * @return SiteLookup
 371          */
 372         public function getSiteLookup() {
 373                 return $this->getService( 'SiteLookup' );
 374         }
 375
 376         /**
 377          * @since 1.27
 378          * @return SiteStore
 379          */
 380         public function getSiteStore() {
 381                 return $this->getService( 'SiteStore' );
 382         }
 383
 384         /**
 385          * @since 1.27
 386          * @return StatsdDataFactory
 387          */
 388         public function getStatsdDataFactory() {
 389                 return $this->getService( 'StatsdDataFactory' );
 390         }
 391
 392         /**
 393          * @since 1.27
 394          * @return EventRelayerGroup
 395          */
 396         public function getEventRelayerGroup() {
 397                 return $this->getService( 'EventRelayerGroup' );
 398         }
 399
 400         /**
 401          * @since 1.27
 402          * @return SearchEngine
 403          */
 404         public function newSearchEngine() {
 405                 // New engine object every time, since they keep state
 406                 return $this->getService( 'SearchEngineFactory' )->create();
 407         }
 408
 409         /**
 410          * @since 1.27
 411          * @return SearchEngineFactory
 412          */
 413         public function getSearchEngineFactory() {
 414                 return $this->getService( 'SearchEngineFactory' );
 415         }
 416
 417         /**
 418          * @since 1.27
 419          * @return SearchEngineConfig
 420          */
 421         public function getSearchEngineConfig() {
 422                 return $this->getService( 'SearchEngineConfig' );
 423         }
 424
 425         /**
 426          * @since 1.27
 427          * @return SkinFactory
 428          */
 429         public function getSkinFactory() {
 430                 return $this->getService( 'SkinFactory' );
 431         }
 432
 433         /**
 434          * @since 1.28
 435          * @return LBFactory
 436          */
 437         public function getDBLoadBalancerFactory() {
 438                 return $this->getService( 'DBLoadBalancerFactory' );
 439         }
 440
 441         /**
 442          * @since 1.28
 443          * @return LoadBalancer The main DB load balancer for the local wiki.
 444          */
 445         public function getDBLoadBalancer() {
 446                 return $this->getService( 'DBLoadBalancer' );
 447         }
 448
 449         /**
 450          * @since 1.28
 451          * @return WatchedItemStore
 452          */
 453         public function getWatchedItemStore() {
 454                 return $this->getService( 'WatchedItemStore' );
 455         }
 456
 457         /**
 458          * @since 1.28
 459          * @return GenderCache
 460          */
 461         public function getGenderCache() {
 462                 return $this->getService( 'GenderCache' );
 463         }
 464
 465         /**
 466          * @since 1.28
 467          * @return LinkCache
 468          */
 469         public function getLinkCache() {
 470                 return $this->getService( 'LinkCache' );
 471         }
 472
 473         /**
 474          * @since 1.28
 475          * @return TitleFormatter
 476          */
 477         public function getTitleFormatter() {
 478                 return $this->getService( 'TitleFormatter' );
 479         }
 480
 481         /**
 482          * @since 1.28
 483          * @return TitleParser
 484          */
 485         public function getTitleParser() {
 486                 return $this->getService( 'TitleParser' );
 487         }
 488
 489         ///////////////////////////////////////////////////////////////////////////
 490         // NOTE: When adding a service getter here, don't forget to add a test
 491         // case for it in MediaWikiServicesTest::provideGetters() and in
 492         // MediaWikiServicesTest::provideGetService()!
 493         ///////////////////////////////////////////////////////////////////////////
 494
 495 }