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