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 LinkCache;
  12 use Liuggio\StatsdClient\Factory\StatsdDataFactory;
  13 use LoadBalancer;
  14 use MediaWiki\Services\ServiceContainer;
  15 use MWException;
  16 use ObjectCache;
  17 use ResourceLoader;
  18 use SearchEngine;
  19 use SearchEngineConfig;
  20 use SearchEngineFactory;
  21 use SiteLookup;
  22 use SiteStore;
  23 use WatchedItemStore;
  24 use SkinFactory;
  25 use TitleFormatter;
  26 use TitleParser;
  27
  28 /**
  29  * Service locator for MediaWiki core services.
  30  *
  31  * This program is free software; you can redistribute it and/or modify
  32  * it under the terms of the GNU General Public License as published by
  33  * the Free Software Foundation; either version 2 of the License, or
  34  * (at your option) any later version.
  35  *
  36  * This program is distributed in the hope that it will be useful,
  37  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  38  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  39  * GNU General Public License for more details.
  40  *
  41  * You should have received a copy of the GNU General Public License along
  42  * with this program; if not, write to the Free Software Foundation, Inc.,
  43  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  44  * http://www.gnu.org/copyleft/gpl.html
  45  *
  46  * @file
  47  *
  48  * @since 1.27
  49  */
  50
  51 /**
  52  * MediaWikiServices is the service locator for the application scope of MediaWiki.
  53  * Its implemented as a simple configurable DI container.
  54  * MediaWikiServices acts as a top level factory/registry for top level services, and builds
  55  * the network of service objects that defines MediaWiki's application logic.
  56  * It acts as an entry point to MediaWiki's dependency injection mechanism.
  57  *
  58  * Services are defined in the "wiring" array passed to the constructor,
  59  * or by calling defineService().
  60  *
  61  * @see docs/injection.txt for an overview of using dependency injection in the
  62  *      MediaWiki code base.
  63  */
  64 class MediaWikiServices extends ServiceContainer {
  65
  66         /**
  67          * @var MediaWikiServices|null
  68          */
  69         private static $instance = null;
  70
  71         /**
  72          * Returns the global default instance of the top level service locator.
  73          *
  74          * @since 1.27
  75          *
  76          * The default instance is initialized using the service instantiator functions
  77          * defined in ServiceWiring.php.
  78          *
  79          * @note This should only be called by static functions! The instance returned here
  80          * should not be passed around! Objects that need access to a service should have
  81          * that service injected into the constructor, never a service locator!
  82          *
  83          * @return MediaWikiServices
  84          */
  85         public static function getInstance() {
  86                 if ( self::$instance === null ) {
  87                         // NOTE: constructing GlobalVarConfig here is not particularly pretty,
  88                         // but some information from the global scope has to be injected here,
  89                         // even if it's just a file name or database credentials to load
  90                         // configuration from.
  91                         $bootstrapConfig = new GlobalVarConfig();
  92                         self::$instance = self::newInstance( $bootstrapConfig );
  93                 }
  94
  95                 return self::$instance;
  96         }
  97
  98         /**
  99          * Replaces the global MediaWikiServices instance.
 100          *
 101          * @since 1.28
 102          *
 103          * @note This is for use in PHPUnit tests only!
 104          *
 105          * @throws MWException if called outside of PHPUnit tests.
 106          *
 107          * @param MediaWikiServices $services The new MediaWikiServices object.
 108          *
 109          * @return MediaWikiServices The old MediaWikiServices object, so it can be restored later.
 110          */
 111         public static function forceGlobalInstance( MediaWikiServices $services ) {
 112                 if ( !defined( 'MW_PHPUNIT_TEST' ) ) {
 113                         throw new MWException( __METHOD__ . ' must not be used outside unit tests.' );
 114                 }
 115
 116                 $old = self::getInstance();
 117                 self::$instance = $services;
 118
 119                 return $old;
 120         }
 121
 122         /**
 123          * Creates a new instance of MediaWikiServices and sets it as the global default
 124          * instance. getInstance() will return a different MediaWikiServices object
 125          * after every call to resetGlobalServiceLocator().
 126          *
 127          * @since 1.28
 128          *
 129          * @warning This should not be used during normal operation. It is intended for use
 130          * when the configuration has changed significantly since bootstrap time, e.g.
 131          * during the installation process or during testing.
 132          *
 133          * @warning Calling resetGlobalServiceLocator() may leave the application in an inconsistent
 134          * state. Calling this is only safe under the ASSUMPTION that NO REFERENCE to
 135          * any of the services managed by MediaWikiServices exist. If any service objects
 136          * managed by the old MediaWikiServices instance remain in use, they may INTERFERE
 137          * with the operation of the services managed by the new MediaWikiServices.
 138          * Operating with a mix of services created by the old and the new
 139          * MediaWikiServices instance may lead to INCONSISTENCIES and even DATA LOSS!
 140          * Any class implementing LAZY LOADING is especially prone to this problem,
 141          * since instances would typically retain a reference to a storage layer service.
 142          *
 143          * @see forceGlobalInstance()
 144          * @see resetGlobalInstance()
 145          * @see resetBetweenTest()
 146          *
 147          * @param Config|null $bootstrapConfig The Config object to be registered as the
 148          *        'BootstrapConfig' service. This has to contain at least the information
 149          *        needed to set up the 'ConfigFactory' service. If not given, the bootstrap
 150          *        config of the old instance of MediaWikiServices will be re-used. If there
 151          *        was no previous instance, a new GlobalVarConfig object will be used to
 152          *        bootstrap the services.
 153          *
 154          * @throws MWException If called after MW_SERVICE_BOOTSTRAP_COMPLETE has been defined in
 155          *         Setup.php (unless MW_PHPUNIT_TEST or MEDIAWIKI_INSTALL or RUN_MAINTENANCE_IF_MAIN
 156          *          is defined).
 157          */
 158         public static function resetGlobalInstance( Config $bootstrapConfig = null ) {
 159                 if ( self::$instance === null ) {
 160                         // no global instance yet, nothing to reset
 161                         return;
 162                 }
 163
 164                 self::failIfResetNotAllowed( __METHOD__ );
 165
 166                 if ( $bootstrapConfig === null ) {
 167                         $bootstrapConfig = self::$instance->getBootstrapConfig();
 168                 }
 169
 170                 self::$instance->destroy();
 171
 172                 self::$instance = self::newInstance( $bootstrapConfig );
 173         }
 174
 175         /**
 176          * Creates a new MediaWikiServices instance and initializes it according to the
 177          * given $bootstrapConfig. In particular, all wiring files defined in the
 178          * ServiceWiringFiles setting are loaded, and the MediaWikiServices hook is called.
 179          *
 180          * @param Config|null $bootstrapConfig The Config object to be registered as the
 181          *        'BootstrapConfig' service. This has to contain at least the information
 182          *        needed to set up the 'ConfigFactory' service. If not provided, any call
 183          *        to getBootstrapConfig(), getConfigFactory, or getMainConfig will fail.
 184          *        A MediaWikiServices instance without access to configuration is called
 185          *        "primordial".
 186          *
 187          * @return MediaWikiServices
 188          * @throws MWException
 189          */
 190         private static function newInstance( Config $bootstrapConfig ) {
 191                 $instance = new self( $bootstrapConfig );
 192
 193                 // Load the default wiring from the specified files.
 194                 $wiringFiles = $bootstrapConfig->get( 'ServiceWiringFiles' );
 195                 $instance->loadWiringFiles( $wiringFiles );
 196
 197                 // Provide a traditional hook point to allow extensions to configure services.
 198                 Hooks::run( 'MediaWikiServices', [ $instance ] );
 199
 200                 return $instance;
 201         }
 202
 203         /**
 204          * Disables all storage layer services. After calling this, any attempt to access the
 205          * storage layer will result in an error. Use resetGlobalInstance() to restore normal
 206          * operation.
 207          *
 208          * @since 1.28
 209          *
 210          * @warning This is intended for extreme situations only and should never be used
 211          * while serving normal web requests. Legitimate use cases for this method include
 212          * the installation process. Test fixtures may also use this, if the fixture relies
 213          * on globalState.
 214          *
 215          * @see resetGlobalInstance()
 216          * @see resetChildProcessServices()
 217          */
 218         public static function disableStorageBackend() {
 219                 // TODO: also disable some Caches, JobQueues, etc
 220                 $destroy = [ 'DBLoadBalancer', 'DBLoadBalancerFactory' ];
 221                 $services = self::getInstance();
 222
 223                 foreach ( $destroy as $name ) {
 224                         $services->disableService( $name );
 225                 }
 226
 227                 ObjectCache::clear();
 228         }
 229
 230         /**
 231          * Resets any services that may have become stale after a child process
 232          * returns from after pcntl_fork(). It's also safe, but generally unnecessary,
 233          * to call this method from the parent process.
 234          *
 235          * @since 1.28
 236          *
 237          * @note This is intended for use in the context of process forking only!
 238          *
 239          * @see resetGlobalInstance()
 240          * @see disableStorageBackend()
 241          */
 242         public static function resetChildProcessServices() {
 243                 // NOTE: for now, just reset everything. Since we don't know the interdependencies
 244                 // between services, we can't do this more selectively at this time.
 245                 self::resetGlobalInstance();
 246
 247                 // Child, reseed because there is no bug in PHP:
 248                 // http://bugs.php.net/bug.php?id=42465
 249                 mt_srand( getmypid() );
 250         }
 251
 252         /**
 253          * Resets the given service for testing purposes.
 254          *
 255          * @since 1.28
 256          *
 257          * @warning This is generally unsafe! Other services may still retain references
 258          * to the stale service instance, leading to failures and inconsistencies. Subclasses
 259          * may use this method to reset specific services under specific instances, but
 260          * it should not be exposed to application logic.
 261          *
 262          * @note With proper dependency injection used throughout the codebase, this method
 263          * should not be needed. It is provided to allow tests that pollute global service
 264          * instances to clean up.
 265          *
 266          * @param string $name
 267          * @param string $destroy Whether the service instance should be destroyed if it exists.
 268          *        When set to false, any existing service instance will effectively be detached
 269          *        from the container.
 270          *
 271          * @throws MWException if called outside of PHPUnit tests.
 272          */
 273         public function resetServiceForTesting( $name, $destroy = true ) {
 274                 if ( !defined( 'MW_PHPUNIT_TEST' ) && !defined( 'MW_PARSER_TEST' ) ) {
 275                         throw new MWException( 'resetServiceForTesting() must not be used outside unit tests.' );
 276                 }
 277
 278                 $this->resetService( $name, $destroy );
 279         }
 280
 281         /**
 282          * Convenience method that throws an exception unless it is called during a phase in which
 283          * resetting of global services is allowed. In general, services should not be reset
 284          * individually, since that may introduce inconsistencies.
 285          *
 286          * @since 1.28
 287          *
 288          * This method will throw an exception if:
 289          *
 290          * - self::$resetInProgress is false (to allow all services to be reset together
 291          *   via resetGlobalInstance)
 292          * - and MEDIAWIKI_INSTALL is not defined (to allow services to be reset during installation)
 293          * - and MW_PHPUNIT_TEST is not defined (to allow services to be reset during testing)
 294          *
 295          * This method is intended to be used to safeguard against accidentally resetting
 296          * global service instances that are not yet managed by MediaWikiServices. It is
 297          * defined here in the MediaWikiServices services class to have a central place
 298          * for managing service bootstrapping and resetting.
 299          *
 300          * @param string $method the name of the caller method, as given by __METHOD__.
 301          *
 302          * @throws MWException if called outside bootstrap mode.
 303          *
 304          * @see resetGlobalInstance()
 305          * @see forceGlobalInstance()
 306          * @see disableStorageBackend()
 307          */
 308         public static function failIfResetNotAllowed( $method ) {
 309                 if ( !defined( 'MW_PHPUNIT_TEST' )
 310                         && !defined( 'MW_PARSER_TEST' )
 311                         && !defined( 'MEDIAWIKI_INSTALL' )
 312                         && !defined( 'RUN_MAINTENANCE_IF_MAIN' )
 313                         && defined( 'MW_SERVICE_BOOTSTRAP_COMPLETE' )
 314                 ) {
 315                         throw new MWException( $method . ' may only be called during bootstrapping and unit tests!' );
 316                 }
 317         }
 318
 319         /**
 320          * @param Config $config The Config object to be registered as the 'BootstrapConfig' service.
 321          *        This has to contain at least the information needed to set up the 'ConfigFactory'
 322          *        service.
 323          */
 324         public function __construct( Config $config ) {
 325                 parent::__construct();
 326
 327                 // Register the given Config object as the bootstrap config service.
 328                 $this->defineService( 'BootstrapConfig', function() use ( $config ) {
 329                         return $config;
 330                 } );
 331         }
 332
 333         // CONVENIENCE GETTERS ////////////////////////////////////////////////////
 334
 335         /**
 336          * Returns the Config object containing the bootstrap configuration.
 337          * Bootstrap configuration would typically include database credentials
 338          * and other information that may be needed before the ConfigFactory
 339          * service can be instantiated.
 340          *
 341          * @note This should only be used during bootstrapping, in particular
 342          * when creating the MainConfig service. Application logic should
 343          * use getMainConfig() to get a Config instances.
 344          *
 345          * @since 1.27
 346          * @return Config
 347          */
 348         public function getBootstrapConfig() {
 349                 return $this->getService( 'BootstrapConfig' );
 350         }
 351
 352         /**
 353          * @since 1.27
 354          * @return ConfigFactory
 355          */
 356         public function getConfigFactory() {
 357                 return $this->getService( 'ConfigFactory' );
 358         }
 359
 360         /**
 361          * Returns the Config object that provides configuration for MediaWiki core.
 362          * This may or may not be the same object that is returned by getBootstrapConfig().
 363          *
 364          * @since 1.27
 365          * @return Config
 366          */
 367         public function getMainConfig() {
 368                 return $this->getService( 'MainConfig' );
 369         }
 370
 371         /**
 372          * @since 1.27
 373          * @return SiteLookup
 374          */
 375         public function getSiteLookup() {
 376                 return $this->getService( 'SiteLookup' );
 377         }
 378
 379         /**
 380          * @since 1.27
 381          * @return SiteStore
 382          */
 383         public function getSiteStore() {
 384                 return $this->getService( 'SiteStore' );
 385         }
 386
 387         /**
 388          * @since 1.27
 389          * @return StatsdDataFactory
 390          */
 391         public function getStatsdDataFactory() {
 392                 return $this->getService( 'StatsdDataFactory' );
 393         }
 394
 395         /**
 396          * @since 1.27
 397          * @return EventRelayerGroup
 398          */
 399         public function getEventRelayerGroup() {
 400                 return $this->getService( 'EventRelayerGroup' );
 401         }
 402
 403         /**
 404          * @since 1.27
 405          * @return SearchEngine
 406          */
 407         public function newSearchEngine() {
 408                 // New engine object every time, since they keep state
 409                 return $this->getService( 'SearchEngineFactory' )->create();
 410         }
 411
 412         /**
 413          * @since 1.27
 414          * @return SearchEngineFactory
 415          */
 416         public function getSearchEngineFactory() {
 417                 return $this->getService( 'SearchEngineFactory' );
 418         }
 419
 420         /**
 421          * @since 1.27
 422          * @return SearchEngineConfig
 423          */
 424         public function getSearchEngineConfig() {
 425                 return $this->getService( 'SearchEngineConfig' );
 426         }
 427
 428         /**
 429          * @since 1.27
 430          * @return SkinFactory
 431          */
 432         public function getSkinFactory() {
 433                 return $this->getService( 'SkinFactory' );
 434         }
 435
 436         /**
 437          * @since 1.28
 438          * @return LBFactory
 439          */
 440         public function getDBLoadBalancerFactory() {
 441                 return $this->getService( 'DBLoadBalancerFactory' );
 442         }
 443
 444         /**
 445          * @since 1.28
 446          * @return LoadBalancer The main DB load balancer for the local wiki.
 447          */
 448         public function getDBLoadBalancer() {
 449                 return $this->getService( 'DBLoadBalancer' );
 450         }
 451
 452         /**
 453          * @since 1.28
 454          * @return WatchedItemStore
 455          */
 456         public function getWatchedItemStore() {
 457                 return $this->getService( 'WatchedItemStore' );
 458         }
 459
 460         /**
 461          * @since 1.28
 462          * @return GenderCache
 463          */
 464         public function getGenderCache() {
 465                 return $this->getService( 'GenderCache' );
 466         }
 467
 468         /**
 469          * @since 1.28
 470          * @return LinkCache
 471          */
 472         public function getLinkCache() {
 473                 return $this->getService( 'LinkCache' );
 474         }
 475
 476         /**
 477          * @since 1.28
 478          * @return TitleFormatter
 479          */
 480         public function getTitleFormatter() {
 481                 return $this->getService( 'TitleFormatter' );
 482         }
 483
 484         /**
 485          * @since 1.28
 486          * @return TitleParser
 487          */
 488         public function getTitleParser() {
 489                 return $this->getService( 'TitleParser' );
 490         }
 491
 492         ///////////////////////////////////////////////////////////////////////////
 493         // NOTE: When adding a service getter here, don't forget to add a test
 494         // case for it in MediaWikiServicesTest::provideGetters() and in
 495         // MediaWikiServicesTest::provideGetService()!
 496         ///////////////////////////////////////////////////////////////////////////
 497
 498 }