includes/resourceloader/ResourceLoaderModule.php

   1 <?php
   2 /**
   3  * Abstraction for ResourceLoader modules.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @author Trevor Parscal
  22  * @author Roan Kattouw
  23  */
  24
  25 use Psr\Log\LoggerAwareInterface;
  26 use Psr\Log\LoggerInterface;
  27 use Psr\Log\NullLogger;
  28
  29 /**
  30  * Abstraction for ResourceLoader modules, with name registration and maxage functionality.
  31  */
  32 abstract class ResourceLoaderModule implements LoggerAwareInterface {
  33         # Type of resource
  34         const TYPE_SCRIPTS = 'scripts';
  35         const TYPE_STYLES = 'styles';
  36         const TYPE_COMBINED = 'combined';
  37
  38         # Desired load type
  39         // Module only has styles (loaded via <style> or <link rel=stylesheet>)
  40         const LOAD_STYLES = 'styles';
  41         // Module may have other resources (loaded via mw.loader from a script)
  42         const LOAD_GENERAL = 'general';
  43
  44         # sitewide core module like a skin file or jQuery component
  45         const ORIGIN_CORE_SITEWIDE = 1;
  46
  47         # per-user module generated by the software
  48         const ORIGIN_CORE_INDIVIDUAL = 2;
  49
  50         # sitewide module generated from user-editable files, like MediaWiki:Common.js, or
  51         # modules accessible to multiple users, such as those generated by the Gadgets extension.
  52         const ORIGIN_USER_SITEWIDE = 3;
  53
  54         # per-user module generated from user-editable files, like User:Me/vector.js
  55         const ORIGIN_USER_INDIVIDUAL = 4;
  56
  57         # an access constant; make sure this is kept as the largest number in this group
  58         const ORIGIN_ALL = 10;
  59
  60         # script and style modules form a hierarchy of trustworthiness, with core modules like
  61         # skins and jQuery as most trustworthy, and user scripts as least trustworthy.  We can
  62         # limit the types of scripts and styles we allow to load on, say, sensitive special
  63         # pages like Special:UserLogin and Special:Preferences
  64         protected $origin = self::ORIGIN_CORE_SITEWIDE;
  65
  66         /* Protected Members */
  67
  68         protected $name = null;
  69         protected $targets = [ 'desktop' ];
  70
  71         // In-object cache for file dependencies
  72         protected $fileDeps = [];
  73         // In-object cache for message blob (keyed by language)
  74         protected $msgBlobs = [];
  75         // In-object cache for version hash
  76         protected $versionHash = [];
  77         // In-object cache for module content
  78         protected $contents = [];
  79
  80         /**
  81          * @var Config
  82          */
  83         protected $config;
  84
  85         /**
  86          * @var LoggerInterface
  87          */
  88         protected $logger;
  89
  90         /* Methods */
  91
  92         /**
  93          * Get this module's name. This is set when the module is registered
  94          * with ResourceLoader::register()
  95          *
  96          * @return string|null Name (string) or null if no name was set
  97          */
  98         public function getName() {
  99                 return $this->name;
 100         }
 101
 102         /**
 103          * Set this module's name. This is called by ResourceLoader::register()
 104          * when registering the module. Other code should not call this.
 105          *
 106          * @param string $name Name
 107          */
 108         public function setName( $name ) {
 109                 $this->name = $name;
 110         }
 111
 112         /**
 113          * Get this module's origin. This is set when the module is registered
 114          * with ResourceLoader::register()
 115          *
 116          * @return int ResourceLoaderModule class constant, the subclass default
 117          *     if not set manually
 118          */
 119         public function getOrigin() {
 120                 return $this->origin;
 121         }
 122
 123         /**
 124          * @param ResourceLoaderContext $context
 125          * @return bool
 126          */
 127         public function getFlip( $context ) {
 128                 global $wgContLang;
 129
 130                 return $wgContLang->getDir() !== $context->getDirection();
 131         }
 132
 133         /**
 134          * Get all JS for this module for a given language and skin.
 135          * Includes all relevant JS except loader scripts.
 136          *
 137          * @param ResourceLoaderContext $context
 138          * @return string JavaScript code
 139          */
 140         public function getScript( ResourceLoaderContext $context ) {
 141                 // Stub, override expected
 142                 return '';
 143         }
 144
 145         /**
 146          * Takes named templates by the module and returns an array mapping.
 147          *
 148          * @return array of templates mapping template alias to content
 149          */
 150         public function getTemplates() {
 151                 // Stub, override expected.
 152                 return [];
 153         }
 154
 155         /**
 156          * @return Config
 157          * @since 1.24
 158          */
 159         public function getConfig() {
 160                 if ( $this->config === null ) {
 161                         // Ugh, fall back to default
 162                         $this->config = ConfigFactory::getDefaultInstance()->makeConfig( 'main' );
 163                 }
 164
 165                 return $this->config;
 166         }
 167
 168         /**
 169          * @param Config $config
 170          * @since 1.24
 171          */
 172         public function setConfig( Config $config ) {
 173                 $this->config = $config;
 174         }
 175
 176         /**
 177          * @since 1.27
 178          * @param LoggerInterface $logger
 179          * @return null
 180          */
 181         public function setLogger( LoggerInterface $logger ) {
 182                 $this->logger = $logger;
 183         }
 184
 185         /**
 186          * @since 1.27
 187          * @return LoggerInterface
 188          */
 189         protected function getLogger() {
 190                 if ( !$this->logger ) {
 191                         $this->logger = new NullLogger();
 192                 }
 193                 return $this->logger;
 194         }
 195
 196         /**
 197          * Get the URL or URLs to load for this module's JS in debug mode.
 198          * The default behavior is to return a load.php?only=scripts URL for
 199          * the module, but file-based modules will want to override this to
 200          * load the files directly.
 201          *
 202          * This function is called only when 1) we're in debug mode, 2) there
 203          * is no only= parameter and 3) supportsURLLoading() returns true.
 204          * #2 is important to prevent an infinite loop, therefore this function
 205          * MUST return either an only= URL or a non-load.php URL.
 206          *
 207          * @param ResourceLoaderContext $context
 208          * @return array Array of URLs
 209          */
 210         public function getScriptURLsForDebug( ResourceLoaderContext $context ) {
 211                 $resourceLoader = $context->getResourceLoader();
 212                 $derivative = new DerivativeResourceLoaderContext( $context );
 213                 $derivative->setModules( [ $this->getName() ] );
 214                 $derivative->setOnly( 'scripts' );
 215                 $derivative->setDebug( true );
 216
 217                 $url = $resourceLoader->createLoaderURL(
 218                         $this->getSource(),
 219                         $derivative
 220                 );
 221
 222                 return [ $url ];
 223         }
 224
 225         /**
 226          * Whether this module supports URL loading. If this function returns false,
 227          * getScript() will be used even in cases (debug mode, no only param) where
 228          * getScriptURLsForDebug() would normally be used instead.
 229          * @return bool
 230          */
 231         public function supportsURLLoading() {
 232                 return true;
 233         }
 234
 235         /**
 236          * Get all CSS for this module for a given skin.
 237          *
 238          * @param ResourceLoaderContext $context
 239          * @return array List of CSS strings or array of CSS strings keyed by media type.
 240          *  like array( 'screen' => '.foo { width: 0 }' );
 241          *  or array( 'screen' => array( '.foo { width: 0 }' ) );
 242          */
 243         public function getStyles( ResourceLoaderContext $context ) {
 244                 // Stub, override expected
 245                 return [];
 246         }
 247
 248         /**
 249          * Get the URL or URLs to load for this module's CSS in debug mode.
 250          * The default behavior is to return a load.php?only=styles URL for
 251          * the module, but file-based modules will want to override this to
 252          * load the files directly. See also getScriptURLsForDebug()
 253          *
 254          * @param ResourceLoaderContext $context
 255          * @return array Array( mediaType => array( URL1, URL2, ... ), ... )
 256          */
 257         public function getStyleURLsForDebug( ResourceLoaderContext $context ) {
 258                 $resourceLoader = $context->getResourceLoader();
 259                 $derivative = new DerivativeResourceLoaderContext( $context );
 260                 $derivative->setModules( [ $this->getName() ] );
 261                 $derivative->setOnly( 'styles' );
 262                 $derivative->setDebug( true );
 263
 264                 $url = $resourceLoader->createLoaderURL(
 265                         $this->getSource(),
 266                         $derivative
 267                 );
 268
 269                 return [ 'all' => [ $url ] ];
 270         }
 271
 272         /**
 273          * Get the messages needed for this module.
 274          *
 275          * To get a JSON blob with messages, use MessageBlobStore::get()
 276          *
 277          * @return array List of message keys. Keys may occur more than once
 278          */
 279         public function getMessages() {
 280                 // Stub, override expected
 281                 return [];
 282         }
 283
 284         /**
 285          * Get the group this module is in.
 286          *
 287          * @return string Group name
 288          */
 289         public function getGroup() {
 290                 // Stub, override expected
 291                 return null;
 292         }
 293
 294         /**
 295          * Get the origin of this module. Should only be overridden for foreign modules.
 296          *
 297          * @return string Origin name, 'local' for local modules
 298          */
 299         public function getSource() {
 300                 // Stub, override expected
 301                 return 'local';
 302         }
 303
 304         /**
 305          * Where on the HTML page should this module's JS be loaded?
 306          *  - 'top': in the "<head>"
 307          *  - 'bottom': at the bottom of the "<body>"
 308          *
 309          * @return string
 310          */
 311         public function getPosition() {
 312                 return 'bottom';
 313         }
 314
 315         /**
 316          * Whether this module's JS expects to work without the client-side ResourceLoader module.
 317          * Returning true from this function will prevent mw.loader.state() call from being
 318          * appended to the bottom of the script.
 319          *
 320          * @return bool
 321          */
 322         public function isRaw() {
 323                 return false;
 324         }
 325
 326         /**
 327          * Get a list of modules this module depends on.
 328          *
 329          * Dependency information is taken into account when loading a module
 330          * on the client side.
 331          *
 332          * Note: It is expected that $context will be made non-optional in the near
 333          * future.
 334          *
 335          * @param ResourceLoaderContext $context
 336          * @return array List of module names as strings
 337          */
 338         public function getDependencies( ResourceLoaderContext $context = null ) {
 339                 // Stub, override expected
 340                 return [];
 341         }
 342
 343         /**
 344          * Get target(s) for the module, eg ['desktop'] or ['desktop', 'mobile']
 345          *
 346          * @return array Array of strings
 347          */
 348         public function getTargets() {
 349                 return $this->targets;
 350         }
 351
 352         /**
 353          * Get the module's load type.
 354          *
 355          * @since 1.28
 356          * @return string ResourceLoaderModule LOAD_* constant
 357          */
 358         public function getType() {
 359                 return self::LOAD_GENERAL;
 360         }
 361
 362         /**
 363          * Get the skip function.
 364          *
 365          * Modules that provide fallback functionality can provide a "skip function". This
 366          * function, if provided, will be passed along to the module registry on the client.
 367          * When this module is loaded (either directly or as a dependency of another module),
 368          * then this function is executed first. If the function returns true, the module will
 369          * instantly be considered "ready" without requesting the associated module resources.
 370          *
 371          * The value returned here must be valid javascript for execution in a private function.
 372          * It must not contain the "function () {" and "}" wrapper though.
 373          *
 374          * @return string|null A JavaScript function body returning a boolean value, or null
 375          */
 376         public function getSkipFunction() {
 377                 return null;
 378         }
 379
 380         /**
 381          * Get the files this module depends on indirectly for a given skin.
 382          *
 383          * These are only image files referenced by the module's stylesheet.
 384          *
 385          * @param ResourceLoaderContext $context
 386          * @return array List of files
 387          */
 388         protected function getFileDependencies( ResourceLoaderContext $context ) {
 389                 $vary = $context->getSkin() . '|' . $context->getLanguage();
 390
 391                 // Try in-object cache first
 392                 if ( !isset( $this->fileDeps[$vary] ) ) {
 393                         $dbr = wfGetDB( DB_SLAVE );
 394                         $deps = $dbr->selectField( 'module_deps',
 395                                 'md_deps',
 396                                 [
 397                                         'md_module' => $this->getName(),
 398                                         'md_skin' => $vary,
 399                                 ],
 400                                 __METHOD__
 401                         );
 402
 403                         if ( !is_null( $deps ) ) {
 404                                 $this->fileDeps[$vary] = self::expandRelativePaths(
 405                                         (array)FormatJson::decode( $deps, true )
 406                                 );
 407                         } else {
 408                                 $this->fileDeps[$vary] = [];
 409                         }
 410                 }
 411                 return $this->fileDeps[$vary];
 412         }
 413
 414         /**
 415          * Set in-object cache for file dependencies.
 416          *
 417          * This is used to retrieve data in batches. See ResourceLoader::preloadModuleInfo().
 418          * To save the data, use saveFileDependencies().
 419          *
 420          * @param ResourceLoaderContext $context
 421          * @param string[] $files Array of file names
 422          */
 423         public function setFileDependencies( ResourceLoaderContext $context, $files ) {
 424                 $vary = $context->getSkin() . '|' . $context->getLanguage();
 425                 $this->fileDeps[$vary] = $files;
 426         }
 427
 428         /**
 429          * Set the files this module depends on indirectly for a given skin.
 430          *
 431          * @since 1.27
 432          * @param ResourceLoaderContext $context
 433          * @param array $localFileRefs List of files
 434          */
 435         protected function saveFileDependencies( ResourceLoaderContext $context, $localFileRefs ) {
 436                 // Normalise array
 437                 $localFileRefs = array_values( array_unique( $localFileRefs ) );
 438                 sort( $localFileRefs );
 439
 440                 try {
 441                         // If the list has been modified since last time we cached it, update the cache
 442                         if ( $localFileRefs !== $this->getFileDependencies( $context ) ) {
 443                                 $cache = ObjectCache::getLocalClusterInstance();
 444                                 $key = $cache->makeKey( __METHOD__, $this->getName() );
 445                                 $scopeLock = $cache->getScopedLock( $key, 0 );
 446                                 if ( !$scopeLock ) {
 447                                         return; // T124649; avoid write slams
 448                                 }
 449
 450                                 $vary = $context->getSkin() . '|' . $context->getLanguage();
 451                                 $dbw = wfGetDB( DB_MASTER );
 452                                 $dbw->replace( 'module_deps',
 453                                         [ [ 'md_module', 'md_skin' ] ],
 454                                         [
 455                                                 'md_module' => $this->getName(),
 456                                                 'md_skin' => $vary,
 457                                                 // Use relative paths to avoid ghost entries when $IP changes (T111481)
 458                                                 'md_deps' => FormatJson::encode( self::getRelativePaths( $localFileRefs ) ),
 459                                         ]
 460                                 );
 461
 462                                 $dbw->onTransactionResolution( function () use ( &$scopeLock ) {
 463                                         ScopedCallback::consume( $scopeLock ); // release after commit
 464                                 } );
 465                         }
 466                 } catch ( Exception $e ) {
 467                         wfDebugLog( 'resourceloader', __METHOD__ . ": failed to update DB: $e" );
 468                 }
 469         }
 470
 471         /**
 472          * Make file paths relative to MediaWiki directory.
 473          *
 474          * This is used to make file paths safe for storing in a database without the paths
 475          * becoming stale or incorrect when MediaWiki is moved or upgraded (T111481).
 476          *
 477          * @since 1.27
 478          * @param array $filePaths
 479          * @return array
 480          */
 481         public static function getRelativePaths( array $filePaths ) {
 482                 global $IP;
 483                 return array_map( function ( $path ) use ( $IP ) {
 484                         return RelPath\getRelativePath( $path, $IP );
 485                 }, $filePaths );
 486         }
 487
 488         /**
 489          * Expand directories relative to $IP.
 490          *
 491          * @since 1.27
 492          * @param array $filePaths
 493          * @return array
 494          */
 495         public static function expandRelativePaths( array $filePaths ) {
 496                 global $IP;
 497                 return array_map( function ( $path ) use ( $IP ) {
 498                         return RelPath\joinPath( $IP, $path );
 499                 }, $filePaths );
 500         }
 501
 502         /**
 503          * Get the hash of the message blob.
 504          *
 505          * @since 1.27
 506          * @param ResourceLoaderContext $context
 507          * @return string|null JSON blob or null if module has no messages
 508          */
 509         protected function getMessageBlob( ResourceLoaderContext $context ) {
 510                 if ( !$this->getMessages() ) {
 511                         // Don't bother consulting MessageBlobStore
 512                         return null;
 513                 }
 514                 // Message blobs may only vary language, not by context keys
 515                 $lang = $context->getLanguage();
 516                 if ( !isset( $this->msgBlobs[$lang] ) ) {
 517                         $this->getLogger()->warning( 'Message blob for {module} should have been preloaded', [
 518                                 'module' => $this->getName(),
 519                         ] );
 520                         $store = $context->getResourceLoader()->getMessageBlobStore();
 521                         $this->msgBlobs[$lang] = $store->getBlob( $this, $lang );
 522                 }
 523                 return $this->msgBlobs[$lang];
 524         }
 525
 526         /**
 527          * Set in-object cache for message blobs.
 528          *
 529          * Used to allow fetching of message blobs in batches. See ResourceLoader::preloadModuleInfo().
 530          *
 531          * @since 1.27
 532          * @param string|null $blob JSON blob or null
 533          * @param string $lang Language code
 534          */
 535         public function setMessageBlob( $blob, $lang ) {
 536                 $this->msgBlobs[$lang] = $blob;
 537         }
 538
 539         /**
 540          * Get module-specific LESS variables, if any.
 541          *
 542          * @since 1.27
 543          * @param ResourceLoaderContext $context
 544          * @return array Module-specific LESS variables.
 545          */
 546         protected function getLessVars( ResourceLoaderContext $context ) {
 547                 return [];
 548         }
 549
 550         /**
 551          * Get an array of this module's resources. Ready for serving to the web.
 552          *
 553          * @since 1.26
 554          * @param ResourceLoaderContext $context
 555          * @return array
 556          */
 557         public function getModuleContent( ResourceLoaderContext $context ) {
 558                 $contextHash = $context->getHash();
 559                 // Cache this expensive operation. This calls builds the scripts, styles, and messages
 560                 // content which typically involves filesystem and/or database access.
 561                 if ( !array_key_exists( $contextHash, $this->contents ) ) {
 562                         $this->contents[$contextHash] = $this->buildContent( $context );
 563                 }
 564                 return $this->contents[$contextHash];
 565         }
 566
 567         /**
 568          * Bundle all resources attached to this module into an array.
 569          *
 570          * @since 1.26
 571          * @param ResourceLoaderContext $context
 572          * @return array
 573          */
 574         final protected function buildContent( ResourceLoaderContext $context ) {
 575                 $rl = $context->getResourceLoader();
 576                 $stats = RequestContext::getMain()->getStats();
 577                 $statStart = microtime( true );
 578
 579                 // Only include properties that are relevant to this context (e.g. only=scripts)
 580                 // and that are non-empty (e.g. don't include "templates" for modules without
 581                 // templates). This helps prevent invalidating cache for all modules when new
 582                 // optional properties are introduced.
 583                 $content = [];
 584
 585                 // Scripts
 586                 if ( $context->shouldIncludeScripts() ) {
 587                         // If we are in debug mode, we'll want to return an array of URLs if possible
 588                         // However, we can't do this if the module doesn't support it
 589                         // We also can't do this if there is an only= parameter, because we have to give
 590                         // the module a way to return a load.php URL without causing an infinite loop
 591                         if ( $context->getDebug() && !$context->getOnly() && $this->supportsURLLoading() ) {
 592                                 $scripts = $this->getScriptURLsForDebug( $context );
 593                         } else {
 594                                 $scripts = $this->getScript( $context );
 595                                 // rtrim() because there are usually a few line breaks
 596                                 // after the last ';'. A new line at EOF, a new line
 597                                 // added by ResourceLoaderFileModule::readScriptFiles, etc.
 598                                 if ( is_string( $scripts )
 599                                         && strlen( $scripts )
 600                                         && substr( rtrim( $scripts ), -1 ) !== ';'
 601                                 ) {
 602                                         // Append semicolon to prevent weird bugs caused by files not
 603                                         // terminating their statements right (bug 27054)
 604                                         $scripts .= ";\n";
 605                                 }
 606                         }
 607                         $content['scripts'] = $scripts;
 608                 }
 609
 610                 // Styles
 611                 if ( $context->shouldIncludeStyles() ) {
 612                         $styles = [];
 613                         // Don't create empty stylesheets like array( '' => '' ) for modules
 614                         // that don't *have* any stylesheets (bug 38024).
 615                         $stylePairs = $this->getStyles( $context );
 616                         if ( count( $stylePairs ) ) {
 617                                 // If we are in debug mode without &only= set, we'll want to return an array of URLs
 618                                 // See comment near shouldIncludeScripts() for more details
 619                                 if ( $context->getDebug() && !$context->getOnly() && $this->supportsURLLoading() ) {
 620                                         $styles = [
 621                                                 'url' => $this->getStyleURLsForDebug( $context )
 622                                         ];
 623                                 } else {
 624                                         // Minify CSS before embedding in mw.loader.implement call
 625                                         // (unless in debug mode)
 626                                         if ( !$context->getDebug() ) {
 627                                                 foreach ( $stylePairs as $media => $style ) {
 628                                                         // Can be either a string or an array of strings.
 629                                                         if ( is_array( $style ) ) {
 630                                                                 $stylePairs[$media] = [];
 631                                                                 foreach ( $style as $cssText ) {
 632                                                                         if ( is_string( $cssText ) ) {
 633                                                                                 $stylePairs[$media][] =
 634                                                                                         ResourceLoader::filter( 'minify-css', $cssText );
 635                                                                         }
 636                                                                 }
 637                                                         } elseif ( is_string( $style ) ) {
 638                                                                 $stylePairs[$media] = ResourceLoader::filter( 'minify-css', $style );
 639                                                         }
 640                                                 }
 641                                         }
 642                                         // Wrap styles into @media groups as needed and flatten into a numerical array
 643                                         $styles = [
 644                                                 'css' => $rl->makeCombinedStyles( $stylePairs )
 645                                         ];
 646                                 }
 647                         }
 648                         $content['styles'] = $styles;
 649                 }
 650
 651                 // Messages
 652                 $blob = $this->getMessageBlob( $context );
 653                 if ( $blob ) {
 654                         $content['messagesBlob'] = $blob;
 655                 }
 656
 657                 $templates = $this->getTemplates();
 658                 if ( $templates ) {
 659                         $content['templates'] = $templates;
 660                 }
 661
 662                 $statTiming = microtime( true ) - $statStart;
 663                 $statName = strtr( $this->getName(), '.', '_' );
 664                 $stats->timing( "resourceloader_build.all", 1000 * $statTiming );
 665                 $stats->timing( "resourceloader_build.$statName", 1000 * $statTiming );
 666
 667                 return $content;
 668         }
 669
 670         /**
 671          * Get a string identifying the current version of this module in a given context.
 672          *
 673          * Whenever anything happens that changes the module's response (e.g. scripts, styles, and
 674          * messages) this value must change. This value is used to store module responses in cache.
 675          * (Both client-side and server-side.)
 676          *
 677          * It is not recommended to override this directly. Use getDefinitionSummary() instead.
 678          * If overridden, one must call the parent getVersionHash(), append data and re-hash.
 679          *
 680          * This method should be quick because it is frequently run by ResourceLoaderStartUpModule to
 681          * propagate changes to the client and effectively invalidate cache.
 682          *
 683          * For backward-compatibility, the following optional data providers are automatically included:
 684          *
 685          * - getModifiedTime()
 686          * - getModifiedHash()
 687          *
 688          * @since 1.26
 689          * @param ResourceLoaderContext $context
 690          * @return string Hash (should use ResourceLoader::makeHash)
 691          */
 692         public function getVersionHash( ResourceLoaderContext $context ) {
 693                 // The startup module produces a manifest with versions representing the entire module.
 694                 // Typically, the request for the startup module itself has only=scripts. That must apply
 695                 // only to the startup module content, and not to the module version computed here.
 696                 $context = new DerivativeResourceLoaderContext( $context );
 697                 $context->setModules( [] );
 698                 // Version hash must cover all resources, regardless of startup request itself.
 699                 $context->setOnly( null );
 700                 // Compute version hash based on content, not debug urls.
 701                 $context->setDebug( false );
 702
 703                 // Cache this somewhat expensive operation. Especially because some classes
 704                 // (e.g. startup module) iterate more than once over all modules to get versions.
 705                 $contextHash = $context->getHash();
 706                 if ( !array_key_exists( $contextHash, $this->versionHash ) ) {
 707
 708                         if ( $this->enableModuleContentVersion() ) {
 709                                 // Detect changes directly
 710                                 $str = json_encode( $this->getModuleContent( $context ) );
 711                         } else {
 712                                 // Infer changes based on definition and other metrics
 713                                 $summary = $this->getDefinitionSummary( $context );
 714                                 if ( !isset( $summary['_cacheEpoch'] ) ) {
 715                                         throw new LogicException( 'getDefinitionSummary must call parent method' );
 716                                 }
 717                                 $str = json_encode( $summary );
 718
 719                                 $mtime = $this->getModifiedTime( $context );
 720                                 if ( $mtime !== null ) {
 721                                         // Support: MediaWiki 1.25 and earlier
 722                                         $str .= strval( $mtime );
 723                                 }
 724
 725                                 $mhash = $this->getModifiedHash( $context );
 726                                 if ( $mhash !== null ) {
 727                                         // Support: MediaWiki 1.25 and earlier
 728                                         $str .= strval( $mhash );
 729                                 }
 730                         }
 731
 732                         $this->versionHash[$contextHash] = ResourceLoader::makeHash( $str );
 733                 }
 734                 return $this->versionHash[$contextHash];
 735         }
 736
 737         /**
 738          * Whether to generate version hash based on module content.
 739          *
 740          * If a module requires database or file system access to build the module
 741          * content, consider disabling this in favour of manually tracking relevant
 742          * aspects in getDefinitionSummary(). See getVersionHash() for how this is used.
 743          *
 744          * @return bool
 745          */
 746         public function enableModuleContentVersion() {
 747                 return false;
 748         }
 749
 750         /**
 751          * Get the definition summary for this module.
 752          *
 753          * This is the method subclasses are recommended to use to track values in their
 754          * version hash. Call this in getVersionHash() and pass it to e.g. json_encode.
 755          *
 756          * Subclasses must call the parent getDefinitionSummary() and build on that.
 757          * It is recommended that each subclass appends its own new array. This prevents
 758          * clashes or accidental overwrites of existing keys and gives each subclass
 759          * its own scope for simple array keys.
 760          *
 761          * @code
 762          *     $summary = parent::getDefinitionSummary( $context );
 763          *     $summary[] = array(
 764          *         'foo' => 123,
 765          *         'bar' => 'quux',
 766          *     );
 767          *     return $summary;
 768          * @endcode
 769          *
 770          * Return an array containing values from all significant properties of this
 771          * module's definition.
 772          *
 773          * Be careful not to normalise too much. Especially preserve the order of things
 774          * that carry significance in getScript and getStyles (T39812).
 775          *
 776          * Avoid including things that are insiginificant (e.g. order of message keys is
 777          * insignificant and should be sorted to avoid unnecessary cache invalidation).
 778          *
 779          * This data structure must exclusively contain arrays and scalars as values (avoid
 780          * object instances) to allow simple serialisation using json_encode.
 781          *
 782          * If modules have a hash or timestamp from another source, that may be incuded as-is.
 783          *
 784          * A number of utility methods are available to help you gather data. These are not
 785          * called by default and must be included by the subclass' getDefinitionSummary().
 786          *
 787          * - getMessageBlob()
 788          *
 789          * @since 1.23
 790          * @param ResourceLoaderContext $context
 791          * @return array|null
 792          */
 793         public function getDefinitionSummary( ResourceLoaderContext $context ) {
 794                 return [
 795                         '_class' => get_class( $this ),
 796                         '_cacheEpoch' => $this->getConfig()->get( 'CacheEpoch' ),
 797                 ];
 798         }
 799
 800         /**
 801          * Get this module's last modification timestamp for a given context.
 802          *
 803          * @deprecated since 1.26 Use getDefinitionSummary() instead
 804          * @param ResourceLoaderContext $context Context object
 805          * @return int|null UNIX timestamp
 806          */
 807         public function getModifiedTime( ResourceLoaderContext $context ) {
 808                 return null;
 809         }
 810
 811         /**
 812          * Helper method for providing a version hash to getVersionHash().
 813          *
 814          * @deprecated since 1.26 Use getDefinitionSummary() instead
 815          * @param ResourceLoaderContext $context
 816          * @return string|null Hash
 817          */
 818         public function getModifiedHash( ResourceLoaderContext $context ) {
 819                 return null;
 820         }
 821
 822         /**
 823          * Back-compat dummy for old subclass implementations of getModifiedTime().
 824          *
 825          * This method used to use ObjectCache to track when a hash was first seen. That principle
 826          * stems from a time that ResourceLoader could only identify module versions by timestamp.
 827          * That is no longer the case. Use getDefinitionSummary() directly.
 828          *
 829          * @deprecated since 1.26 Superseded by getVersionHash()
 830          * @param ResourceLoaderContext $context
 831          * @return int UNIX timestamp
 832          */
 833         public function getHashMtime( ResourceLoaderContext $context ) {
 834                 if ( !is_string( $this->getModifiedHash( $context ) ) ) {
 835                         return 1;
 836                 }
 837                 // Dummy that is > 1
 838                 return 2;
 839         }
 840
 841         /**
 842          * Back-compat dummy for old subclass implementations of getModifiedTime().
 843          *
 844          * @since 1.23
 845          * @deprecated since 1.26 Superseded by getVersionHash()
 846          * @param ResourceLoaderContext $context
 847          * @return int UNIX timestamp
 848          */
 849         public function getDefinitionMtime( ResourceLoaderContext $context ) {
 850                 if ( $this->getDefinitionSummary( $context ) === null ) {
 851                         return 1;
 852                 }
 853                 // Dummy that is > 1
 854                 return 2;
 855         }
 856
 857         /**
 858          * Check whether this module is known to be empty. If a child class
 859          * has an easy and cheap way to determine that this module is
 860          * definitely going to be empty, it should override this method to
 861          * return true in that case. Callers may optimize the request for this
 862          * module away if this function returns true.
 863          * @param ResourceLoaderContext $context
 864          * @return bool
 865          */
 866         public function isKnownEmpty( ResourceLoaderContext $context ) {
 867                 return false;
 868         }
 869
 870         /** @var JSParser Lazy-initialized; use self::javaScriptParser() */
 871         private static $jsParser;
 872         private static $parseCacheVersion = 1;
 873
 874         /**
 875          * Validate a given script file; if valid returns the original source.
 876          * If invalid, returns replacement JS source that throws an exception.
 877          *
 878          * @param string $fileName
 879          * @param string $contents
 880          * @return string JS with the original, or a replacement error
 881          */
 882         protected function validateScriptFile( $fileName, $contents ) {
 883                 if ( $this->getConfig()->get( 'ResourceLoaderValidateJS' ) ) {
 884                         // Try for cache hit
 885                         $cache = ObjectCache::getMainWANInstance();
 886                         $key = $cache->makeKey(
 887                                 'resourceloader',
 888                                 'jsparse',
 889                                 self::$parseCacheVersion,
 890                                 md5( $contents )
 891                         );
 892                         $cacheEntry = $cache->get( $key );
 893                         if ( is_string( $cacheEntry ) ) {
 894                                 return $cacheEntry;
 895                         }
 896
 897                         $parser = self::javaScriptParser();
 898                         try {
 899                                 $parser->parse( $contents, $fileName, 1 );
 900                                 $result = $contents;
 901                         } catch ( Exception $e ) {
 902                                 // We'll save this to cache to avoid having to validate broken JS over and over...
 903                                 $err = $e->getMessage();
 904                                 $result = "mw.log.error(" .
 905                                         Xml::encodeJsVar( "JavaScript parse error: $err" ) . ");";
 906                         }
 907
 908                         $cache->set( $key, $result );
 909                         return $result;
 910                 } else {
 911                         return $contents;
 912                 }
 913         }
 914
 915         /**
 916          * @return JSParser
 917          */
 918         protected static function javaScriptParser() {
 919                 if ( !self::$jsParser ) {
 920                         self::$jsParser = new JSParser();
 921                 }
 922                 return self::$jsParser;
 923         }
 924
 925         /**
 926          * Safe version of filemtime(), which doesn't throw a PHP warning if the file doesn't exist.
 927          * Defaults to 1.
 928          *
 929          * @param string $filePath File path
 930          * @return int UNIX timestamp
 931          */
 932         protected static function safeFilemtime( $filePath ) {
 933                 MediaWiki\suppressWarnings();
 934                 $mtime = filemtime( $filePath ) ?: 1;
 935                 MediaWiki\restoreWarnings();
 936                 return $mtime;
 937         }
 938
 939         /**
 940          * Compute a non-cryptographic string hash of a file's contents.
 941          * If the file does not exist or cannot be read, returns an empty string.
 942          *
 943          * @since 1.26 Uses MD4 instead of SHA1.
 944          * @param string $filePath File path
 945          * @return string Hash
 946          */
 947         protected static function safeFileHash( $filePath ) {
 948                 return FileContentsHasher::getFileContentsHash( $filePath );
 949         }
 950 }