includes/MediaWikiServices.php

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