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