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