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