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 MediaWiki\MediaWikiServices;
  26 use Psr\Log\LoggerAwareInterface;
  27 use Psr\Log\LoggerInterface;
  28 use Psr\Log\NullLogger;
  29 use Wikimedia\ScopedCallback;
  30
  31 /**
  32  * Abstraction for ResourceLoader modules, with name registration and maxage functionality.
  33  */
  34 abstract class ResourceLoaderModule implements LoggerAwareInterface {
  35         # Type of resource
  36         const TYPE_SCRIPTS = 'scripts';
  37         const TYPE_STYLES = 'styles';
  38         const TYPE_COMBINED = 'combined';
  39
  40         # Desired load type
  41         // Module only has styles (loaded via <style> or <link rel=stylesheet>)
  42         const LOAD_STYLES = 'styles';
  43         // Module may have other resources (loaded via mw.loader from a script)
  44         const LOAD_GENERAL = 'general';
  45
  46         # sitewide core module like a skin file or jQuery component
  47         const ORIGIN_CORE_SITEWIDE = 1;
  48
  49         # per-user module generated by the software
  50         const ORIGIN_CORE_INDIVIDUAL = 2;
  51
  52         # sitewide module generated from user-editable files, like MediaWiki:Common.js, or
  53         # modules accessible to multiple users, such as those generated by the Gadgets extension.
  54         const ORIGIN_USER_SITEWIDE = 3;
  55
  56         # per-user module generated from user-editable files, like User:Me/vector.js
  57         const ORIGIN_USER_INDIVIDUAL = 4;
  58
  59         # an access constant; make sure this is kept as the largest number in this group
  60         const ORIGIN_ALL = 10;
  61
  62         # script and style modules form a hierarchy of trustworthiness, with core modules like
  63         # skins and jQuery as most trustworthy, and user scripts as least trustworthy.  We can
  64         # limit the types of scripts and styles we allow to load on, say, sensitive special
  65         # pages like Special:UserLogin and Special:Preferences
  66         protected $origin = self::ORIGIN_CORE_SITEWIDE;
  67
  68         /* Protected Members */
  69
  70         protected $name = null;
  71         protected $targets = [ 'desktop' ];
  72
  73         // In-object cache for file dependencies
  74         protected $fileDeps = [];
  75         // In-object cache for message blob (keyed by language)
  76         protected $msgBlobs = [];
  77         // In-object cache for version hash
  78         protected $versionHash = [];
  79         // In-object cache for module content
  80         protected $contents = [];
  81
  82         /**
  83          * @var Config
  84          */
  85         protected $config;
  86
  87         /**
  88          * @var array|bool
  89          */
  90         protected $deprecated = false;
  91
  92         /**
  93          * @var LoggerInterface
  94          */
  95         protected $logger;
  96
  97         /* Methods */
  98
  99         /**
 100          * Get this module's name. This is set when the module is registered
 101          * with ResourceLoader::register()
 102          *
 103          * @return string|null Name (string) or null if no name was set
 104          */
 105         public function getName() {
 106                 return $this->name;
 107         }
 108
 109         /**
 110          * Set this module's name. This is called by ResourceLoader::register()
 111          * when registering the module. Other code should not call this.
 112          *
 113          * @param string $name Name
 114          */
 115         public function setName( $name ) {
 116                 $this->name = $name;
 117         }
 118
 119         /**
 120          * Get this module's origin. This is set when the module is registered
 121          * with ResourceLoader::register()
 122          *
 123          * @return int ResourceLoaderModule class constant, the subclass default
 124          *     if not set manually
 125          */
 126         public function getOrigin() {
 127                 return $this->origin;
 128         }
 129
 130         /**
 131          * @param ResourceLoaderContext $context
 132          * @return bool
 133          */
 134         public function getFlip( $context ) {
 135                 global $wgContLang;
 136
 137                 return $wgContLang->getDir() !== $context->getDirection();
 138         }
 139
 140         /**
 141          * Get JS representing deprecation information for the current module if available
 142          *
 143          * @return string JavaScript code
 144          */
 145         protected function getDeprecationInformation() {
 146                 $deprecationInfo = $this->deprecated;
 147                 if ( $deprecationInfo ) {
 148                         $name = $this->getName();
 149                         $warning = 'This page is using the deprecated ResourceLoader module "' . $name . '".';
 150                         if ( !is_bool( $deprecationInfo ) && isset( $deprecationInfo['message'] ) ) {
 151                                 $warning .= "\n" . $deprecationInfo['message'];
 152                         }
 153                         return Xml::encodeJsCall(
 154                                 'mw.log.warn',
 155                                 [ $warning ]
 156                         );
 157                 } else {
 158                         return '';
 159                 }
 160         }
 161
 162         /**
 163          * Get all JS for this module for a given language and skin.
 164          * Includes all relevant JS except loader scripts.
 165          *
 166          * @param ResourceLoaderContext $context
 167          * @return string JavaScript code
 168          */
 169         public function getScript( ResourceLoaderContext $context ) {
 170                 // Stub, override expected
 171                 return '';
 172         }
 173
 174         /**
 175          * Takes named templates by the module and returns an array mapping.
 176          *
 177          * @return array of templates mapping template alias to content
 178          */
 179         public function getTemplates() {
 180                 // Stub, override expected.
 181                 return [];
 182         }
 183
 184         /**
 185          * @return Config
 186          * @since 1.24
 187          */
 188         public function getConfig() {
 189                 if ( $this->config === null ) {
 190                         // Ugh, fall back to default
 191                         $this->config = MediaWikiServices::getInstance()->getMainConfig();
 192                 }
 193
 194                 return $this->config;
 195         }
 196
 197         /**
 198          * @param Config $config
 199          * @since 1.24
 200          */
 201         public function setConfig( Config $config ) {
 202                 $this->config = $config;
 203         }
 204
 205         /**
 206          * @since 1.27
 207          * @param LoggerInterface $logger
 208          * @return null
 209          */
 210         public function setLogger( LoggerInterface $logger ) {
 211                 $this->logger = $logger;
 212         }
 213
 214         /**
 215          * @since 1.27
 216          * @return LoggerInterface
 217          */
 218         protected function getLogger() {
 219                 if ( !$this->logger ) {
 220                         $this->logger = new NullLogger();
 221                 }
 222                 return $this->logger;
 223         }
 224
 225         /**
 226          * Get the URL or URLs to load for this module's JS in debug mode.
 227          * The default behavior is to return a load.php?only=scripts URL for
 228          * the module, but file-based modules will want to override this to
 229          * load the files directly.
 230          *
 231          * This function is called only when 1) we're in debug mode, 2) there
 232          * is no only= parameter and 3) supportsURLLoading() returns true.
 233          * #2 is important to prevent an infinite loop, therefore this function
 234          * MUST return either an only= URL or a non-load.php URL.
 235          *
 236          * @param ResourceLoaderContext $context
 237          * @return array Array of URLs
 238          */
 239         public function getScriptURLsForDebug( ResourceLoaderContext $context ) {
 240                 $resourceLoader = $context->getResourceLoader();
 241                 $derivative = new DerivativeResourceLoaderContext( $context );
 242                 $derivative->setModules( [ $this->getName() ] );
 243                 $derivative->setOnly( 'scripts' );
 244                 $derivative->setDebug( true );
 245
 246                 $url = $resourceLoader->createLoaderURL(
 247                         $this->getSource(),
 248                         $derivative
 249                 );
 250
 251                 return [ $url ];
 252         }
 253
 254         /**
 255          * Whether this module supports URL loading. If this function returns false,
 256          * getScript() will be used even in cases (debug mode, no only param) where
 257          * getScriptURLsForDebug() would normally be used instead.
 258          * @return bool
 259          */
 260         public function supportsURLLoading() {
 261                 return true;
 262         }
 263
 264         /**
 265          * Get all CSS for this module for a given skin.
 266          *
 267          * @param ResourceLoaderContext $context
 268          * @return array List of CSS strings or array of CSS strings keyed by media type.
 269          *  like [ 'screen' => '.foo { width: 0 }' ];
 270          *  or [ 'screen' => [ '.foo { width: 0 }' ] ];
 271          */
 272         public function getStyles( ResourceLoaderContext $context ) {
 273                 // Stub, override expected
 274                 return [];
 275         }
 276
 277         /**
 278          * Get the URL or URLs to load for this module's CSS in debug mode.
 279          * The default behavior is to return a load.php?only=styles URL for
 280          * the module, but file-based modules will want to override this to
 281          * load the files directly. See also getScriptURLsForDebug()
 282          *
 283          * @param ResourceLoaderContext $context
 284          * @return array [ mediaType => [ URL1, URL2, ... ], ... ]
 285          */
 286         public function getStyleURLsForDebug( ResourceLoaderContext $context ) {
 287                 $resourceLoader = $context->getResourceLoader();
 288                 $derivative = new DerivativeResourceLoaderContext( $context );
 289                 $derivative->setModules( [ $this->getName() ] );
 290                 $derivative->setOnly( 'styles' );
 291                 $derivative->setDebug( true );
 292
 293                 $url = $resourceLoader->createLoaderURL(
 294                         $this->getSource(),
 295                         $derivative
 296                 );
 297
 298                 return [ 'all' => [ $url ] ];
 299         }
 300
 301         /**
 302          * Get the messages needed for this module.
 303          *
 304          * To get a JSON blob with messages, use MessageBlobStore::get()
 305          *
 306          * @return array List of message keys. Keys may occur more than once
 307          */
 308         public function getMessages() {
 309                 // Stub, override expected
 310                 return [];
 311         }
 312
 313         /**
 314          * Get the group this module is in.
 315          *
 316          * @return string Group name
 317          */
 318         public function getGroup() {
 319                 // Stub, override expected
 320                 return null;
 321         }
 322
 323         /**
 324          * Get the origin of this module. Should only be overridden for foreign modules.
 325          *
 326          * @return string Origin name, 'local' for local modules
 327          */
 328         public function getSource() {
 329                 // Stub, override expected
 330                 return 'local';
 331         }
 332
 333         /**
 334          * From where in the page HTML should this module be loaded?
 335          *
 336          * @deprecated since 1.29 Obsolete. All modules load async from `<head>`.
 337          * @return string
 338          */
 339         public function getPosition() {
 340                 return 'top';
 341         }
 342
 343         /**
 344          * Whether this module's JS expects to work without the client-side ResourceLoader module.
 345          * Returning true from this function will prevent mw.loader.state() call from being
 346          * appended to the bottom of the script.
 347          *
 348          * @return bool
 349          */
 350         public function isRaw() {
 351                 return false;
 352         }
 353
 354         /**
 355          * Get a list of modules this module depends on.
 356          *
 357          * Dependency information is taken into account when loading a module
 358          * on the client side.
 359          *
 360          * Note: It is expected that $context will be made non-optional in the near
 361          * future.
 362          *
 363          * @param ResourceLoaderContext $context
 364          * @return array List of module names as strings
 365          */
 366         public function getDependencies( ResourceLoaderContext $context = null ) {
 367                 // Stub, override expected
 368                 return [];
 369         }
 370
 371         /**
 372          * Get target(s) for the module, eg ['desktop'] or ['desktop', 'mobile']
 373          *
 374          * @return array Array of strings
 375          */
 376         public function getTargets() {
 377                 return $this->targets;
 378         }
 379
 380         /**
 381          * Get the module's load type.
 382          *
 383          * @since 1.28
 384          * @return string ResourceLoaderModule LOAD_* constant
 385          */
 386         public function getType() {
 387                 return self::LOAD_GENERAL;
 388         }
 389
 390         /**
 391          * Get the skip function.
 392          *
 393          * Modules that provide fallback functionality can provide a "skip function". This
 394          * function, if provided, will be passed along to the module registry on the client.
 395          * When this module is loaded (either directly or as a dependency of another module),
 396          * then this function is executed first. If the function returns true, the module will
 397          * instantly be considered "ready" without requesting the associated module resources.
 398          *
 399          * The value returned here must be valid javascript for execution in a private function.
 400          * It must not contain the "function () {" and "}" wrapper though.
 401          *
 402          * @return string|null A JavaScript function body returning a boolean value, or null
 403          */
 404         public function getSkipFunction() {
 405                 return null;
 406         }
 407
 408         /**
 409          * Get the files this module depends on indirectly for a given skin.
 410          *
 411          * These are only image files referenced by the module's stylesheet.
 412          *
 413          * @param ResourceLoaderContext $context
 414          * @return array List of files
 415          */
 416         protected function getFileDependencies( ResourceLoaderContext $context ) {
 417                 $vary = $context->getSkin() . '|' . $context->getLanguage();
 418
 419                 // Try in-object cache first
 420                 if ( !isset( $this->fileDeps[$vary] ) ) {
 421                         $dbr = wfGetDB( DB_REPLICA );
 422                         $deps = $dbr->selectField( 'module_deps',
 423                                 'md_deps',
 424                                 [
 425                                         'md_module' => $this->getName(),
 426                                         'md_skin' => $vary,
 427                                 ],
 428                                 __METHOD__
 429                         );
 430
 431                         if ( !is_null( $deps ) ) {
 432                                 $this->fileDeps[$vary] = self::expandRelativePaths(
 433                                         (array)FormatJson::decode( $deps, true )
 434                                 );
 435                         } else {
 436                                 $this->fileDeps[$vary] = [];
 437                         }
 438                 }
 439                 return $this->fileDeps[$vary];
 440         }
 441
 442         /**
 443          * Set in-object cache for file dependencies.
 444          *
 445          * This is used to retrieve data in batches. See ResourceLoader::preloadModuleInfo().
 446          * To save the data, use saveFileDependencies().
 447          *
 448          * @param ResourceLoaderContext $context
 449          * @param string[] $files Array of file names
 450          */
 451         public function setFileDependencies( ResourceLoaderContext $context, $files ) {
 452                 $vary = $context->getSkin() . '|' . $context->getLanguage();
 453                 $this->fileDeps[$vary] = $files;
 454         }
 455
 456         /**
 457          * Set the files this module depends on indirectly for a given skin.
 458          *
 459          * @since 1.27
 460          * @param ResourceLoaderContext $context
 461          * @param array $localFileRefs List of files
 462          */
 463         protected function saveFileDependencies( ResourceLoaderContext $context, $localFileRefs ) {
 464                 // Normalise array
 465                 $localFileRefs = array_values( array_unique( $localFileRefs ) );
 466                 sort( $localFileRefs );
 467
 468                 try {
 469                         // If the list has been modified since last time we cached it, update the cache
 470                         if ( $localFileRefs !== $this->getFileDependencies( $context ) ) {
 471                                 $cache = ObjectCache::getLocalClusterInstance();
 472                                 $key = $cache->makeKey( __METHOD__, $this->getName() );
 473                                 $scopeLock = $cache->getScopedLock( $key, 0 );
 474                                 if ( !$scopeLock ) {
 475                                         return; // T124649; avoid write slams
 476                                 }
 477
 478                                 $vary = $context->getSkin() . '|' . $context->getLanguage();
 479                                 // Use relative paths to avoid ghost entries when $IP changes (T111481)
 480                                 $deps = FormatJson::encode( self::getRelativePaths( $localFileRefs ) );
 481                                 $dbw = wfGetDB( DB_MASTER );
 482                                 $dbw->upsert( 'module_deps',
 483                                         [
 484                                                 'md_module' => $this->getName(),
 485                                                 'md_skin' => $vary,
 486                                                 'md_deps' => $deps,
 487                                         ],
 488                                         [ 'md_module', 'md_skin' ],
 489                                         [
 490                                                 'md_deps' => $deps,
 491                                         ]
 492                                 );
 493
 494                                 if ( $dbw->trxLevel() ) {
 495                                         $dbw->onTransactionResolution(
 496                                                 function () use ( &$scopeLock ) {
 497                                                         ScopedCallback::consume( $scopeLock ); // release after commit
 498                                                 },
 499                                                 __METHOD__
 500                                         );
 501                                 }
 502                         }
 503                 } catch ( Exception $e ) {
 504                         wfDebugLog( 'resourceloader', __METHOD__ . ": failed to update DB: $e" );
 505                 }
 506         }
 507
 508         /**
 509          * Make file paths relative to MediaWiki directory.
 510          *
 511          * This is used to make file paths safe for storing in a database without the paths
 512          * becoming stale or incorrect when MediaWiki is moved or upgraded (T111481).
 513          *
 514          * @since 1.27
 515          * @param array $filePaths
 516          * @return array
 517          */
 518         public static function getRelativePaths( array $filePaths ) {
 519                 global $IP;
 520                 return array_map( function ( $path ) use ( $IP ) {
 521                         return RelPath\getRelativePath( $path, $IP );
 522                 }, $filePaths );
 523         }
 524
 525         /**
 526          * Expand directories relative to $IP.
 527          *
 528          * @since 1.27
 529          * @param array $filePaths
 530          * @return array
 531          */
 532         public static function expandRelativePaths( array $filePaths ) {
 533                 global $IP;
 534                 return array_map( function ( $path ) use ( $IP ) {
 535                         return RelPath\joinPath( $IP, $path );
 536                 }, $filePaths );
 537         }
 538
 539         /**
 540          * Get the hash of the message blob.
 541          *
 542          * @since 1.27
 543          * @param ResourceLoaderContext $context
 544          * @return string|null JSON blob or null if module has no messages
 545          */
 546         protected function getMessageBlob( ResourceLoaderContext $context ) {
 547                 if ( !$this->getMessages() ) {
 548                         // Don't bother consulting MessageBlobStore
 549                         return null;
 550                 }
 551                 // Message blobs may only vary language, not by context keys
 552                 $lang = $context->getLanguage();
 553                 if ( !isset( $this->msgBlobs[$lang] ) ) {
 554                         $this->getLogger()->warning( 'Message blob for {module} should have been preloaded', [
 555                                 'module' => $this->getName(),
 556                         ] );
 557                         $store = $context->getResourceLoader()->getMessageBlobStore();
 558                         $this->msgBlobs[$lang] = $store->getBlob( $this, $lang );
 559                 }
 560                 return $this->msgBlobs[$lang];
 561         }
 562
 563         /**
 564          * Set in-object cache for message blobs.
 565          *
 566          * Used to allow fetching of message blobs in batches. See ResourceLoader::preloadModuleInfo().
 567          *
 568          * @since 1.27
 569          * @param string|null $blob JSON blob or null
 570          * @param string $lang Language code
 571          */
 572         public function setMessageBlob( $blob, $lang ) {
 573                 $this->msgBlobs[$lang] = $blob;
 574         }
 575
 576         /**
 577          * Get module-specific LESS variables, if any.
 578          *
 579          * @since 1.27
 580          * @param ResourceLoaderContext $context
 581          * @return array Module-specific LESS variables.
 582          */
 583         protected function getLessVars( ResourceLoaderContext $context ) {
 584                 return [];
 585         }
 586
 587         /**
 588          * Get an array of this module's resources. Ready for serving to the web.
 589          *
 590          * @since 1.26
 591          * @param ResourceLoaderContext $context
 592          * @return array
 593          */
 594         public function getModuleContent( ResourceLoaderContext $context ) {
 595                 $contextHash = $context->getHash();
 596                 // Cache this expensive operation. This calls builds the scripts, styles, and messages
 597                 // content which typically involves filesystem and/or database access.
 598                 if ( !array_key_exists( $contextHash, $this->contents ) ) {
 599                         $this->contents[$contextHash] = $this->buildContent( $context );
 600                 }
 601                 return $this->contents[$contextHash];
 602         }
 603
 604         /**
 605          * Bundle all resources attached to this module into an array.
 606          *
 607          * @since 1.26
 608          * @param ResourceLoaderContext $context
 609          * @return array
 610          */
 611         final protected function buildContent( ResourceLoaderContext $context ) {
 612                 $rl = $context->getResourceLoader();
 613                 $stats = RequestContext::getMain()->getStats();
 614                 $statStart = microtime( true );
 615
 616                 // Only include properties that are relevant to this context (e.g. only=scripts)
 617                 // and that are non-empty (e.g. don't include "templates" for modules without
 618                 // templates). This helps prevent invalidating cache for all modules when new
 619                 // optional properties are introduced.
 620                 $content = [];
 621
 622                 // Scripts
 623                 if ( $context->shouldIncludeScripts() ) {
 624                         // If we are in debug mode, we'll want to return an array of URLs if possible
 625                         // However, we can't do this if the module doesn't support it
 626                         // We also can't do this if there is an only= parameter, because we have to give
 627                         // the module a way to return a load.php URL without causing an infinite loop
 628                         if ( $context->getDebug() && !$context->getOnly() && $this->supportsURLLoading() ) {
 629                                 $scripts = $this->getScriptURLsForDebug( $context );
 630                         } else {
 631                                 $scripts = $this->getScript( $context );
 632                                 // rtrim() because there are usually a few line breaks
 633                                 // after the last ';'. A new line at EOF, a new line
 634                                 // added by ResourceLoaderFileModule::readScriptFiles, etc.
 635                                 if ( is_string( $scripts )
 636                                         && strlen( $scripts )
 637                                         && substr( rtrim( $scripts ), -1 ) !== ';'
 638                                 ) {
 639                                         // Append semicolon to prevent weird bugs caused by files not
 640                                         // terminating their statements right (bug 27054)
 641                                         $scripts .= ";\n";
 642                                 }
 643                         }
 644                         $content['scripts'] = $scripts;
 645                 }
 646
 647                 // Styles
 648                 if ( $context->shouldIncludeStyles() ) {
 649                         $styles = [];
 650                         // Don't create empty stylesheets like [ '' => '' ] for modules
 651                         // that don't *have* any stylesheets (bug 38024).
 652                         $stylePairs = $this->getStyles( $context );
 653                         if ( count( $stylePairs ) ) {
 654                                 // If we are in debug mode without &only= set, we'll want to return an array of URLs
 655                                 // See comment near shouldIncludeScripts() for more details
 656                                 if ( $context->getDebug() && !$context->getOnly() && $this->supportsURLLoading() ) {
 657                                         $styles = [
 658                                                 'url' => $this->getStyleURLsForDebug( $context )
 659                                         ];
 660                                 } else {
 661                                         // Minify CSS before embedding in mw.loader.implement call
 662                                         // (unless in debug mode)
 663                                         if ( !$context->getDebug() ) {
 664                                                 foreach ( $stylePairs as $media => $style ) {
 665                                                         // Can be either a string or an array of strings.
 666                                                         if ( is_array( $style ) ) {
 667                                                                 $stylePairs[$media] = [];
 668                                                                 foreach ( $style as $cssText ) {
 669                                                                         if ( is_string( $cssText ) ) {
 670                                                                                 $stylePairs[$media][] =
 671                                                                                         ResourceLoader::filter( 'minify-css', $cssText );
 672                                                                         }
 673                                                                 }
 674                                                         } elseif ( is_string( $style ) ) {
 675                                                                 $stylePairs[$media] = ResourceLoader::filter( 'minify-css', $style );
 676                                                         }
 677                                                 }
 678                                         }
 679                                         // Wrap styles into @media groups as needed and flatten into a numerical array
 680                                         $styles = [
 681                                                 'css' => $rl->makeCombinedStyles( $stylePairs )
 682                                         ];
 683                                 }
 684                         }
 685                         $content['styles'] = $styles;
 686                 }
 687
 688                 // Messages
 689                 $blob = $this->getMessageBlob( $context );
 690                 if ( $blob ) {
 691                         $content['messagesBlob'] = $blob;
 692                 }
 693
 694                 $templates = $this->getTemplates();
 695                 if ( $templates ) {
 696                         $content['templates'] = $templates;
 697                 }
 698
 699                 $statTiming = microtime( true ) - $statStart;
 700                 $statName = strtr( $this->getName(), '.', '_' );
 701                 $stats->timing( "resourceloader_build.all", 1000 * $statTiming );
 702                 $stats->timing( "resourceloader_build.$statName", 1000 * $statTiming );
 703
 704                 return $content;
 705         }
 706
 707         /**
 708          * Get a string identifying the current version of this module in a given context.
 709          *
 710          * Whenever anything happens that changes the module's response (e.g. scripts, styles, and
 711          * messages) this value must change. This value is used to store module responses in cache.
 712          * (Both client-side and server-side.)
 713          *
 714          * It is not recommended to override this directly. Use getDefinitionSummary() instead.
 715          * If overridden, one must call the parent getVersionHash(), append data and re-hash.
 716          *
 717          * This method should be quick because it is frequently run by ResourceLoaderStartUpModule to
 718          * propagate changes to the client and effectively invalidate cache.
 719          *
 720          * For backward-compatibility, the following optional data providers are automatically included:
 721          *
 722          * - getModifiedTime()
 723          * - getModifiedHash()
 724          *
 725          * @since 1.26
 726          * @param ResourceLoaderContext $context
 727          * @return string Hash (should use ResourceLoader::makeHash)
 728          */
 729         public function getVersionHash( ResourceLoaderContext $context ) {
 730                 // The startup module produces a manifest with versions representing the entire module.
 731                 // Typically, the request for the startup module itself has only=scripts. That must apply
 732                 // only to the startup module content, and not to the module version computed here.
 733                 $context = new DerivativeResourceLoaderContext( $context );
 734                 $context->setModules( [] );
 735                 // Version hash must cover all resources, regardless of startup request itself.
 736                 $context->setOnly( null );
 737                 // Compute version hash based on content, not debug urls.
 738                 $context->setDebug( false );
 739
 740                 // Cache this somewhat expensive operation. Especially because some classes
 741                 // (e.g. startup module) iterate more than once over all modules to get versions.
 742                 $contextHash = $context->getHash();
 743                 if ( !array_key_exists( $contextHash, $this->versionHash ) ) {
 744
 745                         if ( $this->enableModuleContentVersion() ) {
 746                                 // Detect changes directly
 747                                 $str = json_encode( $this->getModuleContent( $context ) );
 748                         } else {
 749                                 // Infer changes based on definition and other metrics
 750                                 $summary = $this->getDefinitionSummary( $context );
 751                                 if ( !isset( $summary['_cacheEpoch'] ) ) {
 752                                         throw new LogicException( 'getDefinitionSummary must call parent method' );
 753                                 }
 754                                 $str = json_encode( $summary );
 755
 756                                 $mtime = $this->getModifiedTime( $context );
 757                                 if ( $mtime !== null ) {
 758                                         // Support: MediaWiki 1.25 and earlier
 759                                         $str .= strval( $mtime );
 760                                 }
 761
 762                                 $mhash = $this->getModifiedHash( $context );
 763                                 if ( $mhash !== null ) {
 764                                         // Support: MediaWiki 1.25 and earlier
 765                                         $str .= strval( $mhash );
 766                                 }
 767                         }
 768
 769                         $this->versionHash[$contextHash] = ResourceLoader::makeHash( $str );
 770                 }
 771                 return $this->versionHash[$contextHash];
 772         }
 773
 774         /**
 775          * Whether to generate version hash based on module content.
 776          *
 777          * If a module requires database or file system access to build the module
 778          * content, consider disabling this in favour of manually tracking relevant
 779          * aspects in getDefinitionSummary(). See getVersionHash() for how this is used.
 780          *
 781          * @return bool
 782          */
 783         public function enableModuleContentVersion() {
 784                 return false;
 785         }
 786
 787         /**
 788          * Get the definition summary for this module.
 789          *
 790          * This is the method subclasses are recommended to use to track values in their
 791          * version hash. Call this in getVersionHash() and pass it to e.g. json_encode.
 792          *
 793          * Subclasses must call the parent getDefinitionSummary() and build on that.
 794          * It is recommended that each subclass appends its own new array. This prevents
 795          * clashes or accidental overwrites of existing keys and gives each subclass
 796          * its own scope for simple array keys.
 797          *
 798          * @code
 799          *     $summary = parent::getDefinitionSummary( $context );
 800          *     $summary[] = [
 801          *         'foo' => 123,
 802          *         'bar' => 'quux',
 803          *     ];
 804          *     return $summary;
 805          * @endcode
 806          *
 807          * Return an array containing values from all significant properties of this
 808          * module's definition.
 809          *
 810          * Be careful not to normalise too much. Especially preserve the order of things
 811          * that carry significance in getScript and getStyles (T39812).
 812          *
 813          * Avoid including things that are insiginificant (e.g. order of message keys is
 814          * insignificant and should be sorted to avoid unnecessary cache invalidation).
 815          *
 816          * This data structure must exclusively contain arrays and scalars as values (avoid
 817          * object instances) to allow simple serialisation using json_encode.
 818          *
 819          * If modules have a hash or timestamp from another source, that may be incuded as-is.
 820          *
 821          * A number of utility methods are available to help you gather data. These are not
 822          * called by default and must be included by the subclass' getDefinitionSummary().
 823          *
 824          * - getMessageBlob()
 825          *
 826          * @since 1.23
 827          * @param ResourceLoaderContext $context
 828          * @return array|null
 829          */
 830         public function getDefinitionSummary( ResourceLoaderContext $context ) {
 831                 return [
 832                         '_class' => get_class( $this ),
 833                         '_cacheEpoch' => $this->getConfig()->get( 'CacheEpoch' ),
 834                 ];
 835         }
 836
 837         /**
 838          * Get this module's last modification timestamp for a given context.
 839          *
 840          * @deprecated since 1.26 Use getDefinitionSummary() instead
 841          * @param ResourceLoaderContext $context Context object
 842          * @return int|null UNIX timestamp
 843          */
 844         public function getModifiedTime( ResourceLoaderContext $context ) {
 845                 return null;
 846         }
 847
 848         /**
 849          * Helper method for providing a version hash to getVersionHash().
 850          *
 851          * @deprecated since 1.26 Use getDefinitionSummary() instead
 852          * @param ResourceLoaderContext $context
 853          * @return string|null Hash
 854          */
 855         public function getModifiedHash( ResourceLoaderContext $context ) {
 856                 return null;
 857         }
 858
 859         /**
 860          * Back-compat dummy for old subclass implementations of getModifiedTime().
 861          *
 862          * This method used to use ObjectCache to track when a hash was first seen. That principle
 863          * stems from a time that ResourceLoader could only identify module versions by timestamp.
 864          * That is no longer the case. Use getDefinitionSummary() directly.
 865          *
 866          * @deprecated since 1.26 Superseded by getVersionHash()
 867          * @param ResourceLoaderContext $context
 868          * @return int UNIX timestamp
 869          */
 870         public function getHashMtime( ResourceLoaderContext $context ) {
 871                 if ( !is_string( $this->getModifiedHash( $context ) ) ) {
 872                         return 1;
 873                 }
 874                 // Dummy that is > 1
 875                 return 2;
 876         }
 877
 878         /**
 879          * Back-compat dummy for old subclass implementations of getModifiedTime().
 880          *
 881          * @since 1.23
 882          * @deprecated since 1.26 Superseded by getVersionHash()
 883          * @param ResourceLoaderContext $context
 884          * @return int UNIX timestamp
 885          */
 886         public function getDefinitionMtime( ResourceLoaderContext $context ) {
 887                 if ( $this->getDefinitionSummary( $context ) === null ) {
 888                         return 1;
 889                 }
 890                 // Dummy that is > 1
 891                 return 2;
 892         }
 893
 894         /**
 895          * Check whether this module is known to be empty. If a child class
 896          * has an easy and cheap way to determine that this module is
 897          * definitely going to be empty, it should override this method to
 898          * return true in that case. Callers may optimize the request for this
 899          * module away if this function returns true.
 900          * @param ResourceLoaderContext $context
 901          * @return bool
 902          */
 903         public function isKnownEmpty( ResourceLoaderContext $context ) {
 904                 return false;
 905         }
 906
 907         /** @var JSParser Lazy-initialized; use self::javaScriptParser() */
 908         private static $jsParser;
 909         private static $parseCacheVersion = 1;
 910
 911         /**
 912          * Validate a given script file; if valid returns the original source.
 913          * If invalid, returns replacement JS source that throws an exception.
 914          *
 915          * @param string $fileName
 916          * @param string $contents
 917          * @return string JS with the original, or a replacement error
 918          */
 919         protected function validateScriptFile( $fileName, $contents ) {
 920                 if ( $this->getConfig()->get( 'ResourceLoaderValidateJS' ) ) {
 921                         // Try for cache hit
 922                         $cache = ObjectCache::getMainWANInstance();
 923                         $key = $cache->makeKey(
 924                                 'resourceloader',
 925                                 'jsparse',
 926                                 self::$parseCacheVersion,
 927                                 md5( $contents )
 928                         );
 929                         $cacheEntry = $cache->get( $key );
 930                         if ( is_string( $cacheEntry ) ) {
 931                                 return $cacheEntry;
 932                         }
 933
 934                         $parser = self::javaScriptParser();
 935                         try {
 936                                 $parser->parse( $contents, $fileName, 1 );
 937                                 $result = $contents;
 938                         } catch ( Exception $e ) {
 939                                 // We'll save this to cache to avoid having to validate broken JS over and over...
 940                                 $err = $e->getMessage();
 941                                 $result = "mw.log.error(" .
 942                                         Xml::encodeJsVar( "JavaScript parse error: $err" ) . ");";
 943                         }
 944
 945                         $cache->set( $key, $result );
 946                         return $result;
 947                 } else {
 948                         return $contents;
 949                 }
 950         }
 951
 952         /**
 953          * @return JSParser
 954          */
 955         protected static function javaScriptParser() {
 956                 if ( !self::$jsParser ) {
 957                         self::$jsParser = new JSParser();
 958                 }
 959                 return self::$jsParser;
 960         }
 961
 962         /**
 963          * Safe version of filemtime(), which doesn't throw a PHP warning if the file doesn't exist.
 964          * Defaults to 1.
 965          *
 966          * @param string $filePath File path
 967          * @return int UNIX timestamp
 968          */
 969         protected static function safeFilemtime( $filePath ) {
 970                 MediaWiki\suppressWarnings();
 971                 $mtime = filemtime( $filePath ) ?: 1;
 972                 MediaWiki\restoreWarnings();
 973                 return $mtime;
 974         }
 975
 976         /**
 977          * Compute a non-cryptographic string hash of a file's contents.
 978          * If the file does not exist or cannot be read, returns an empty string.
 979          *
 980          * @since 1.26 Uses MD4 instead of SHA1.
 981          * @param string $filePath File path
 982          * @return string Hash
 983          */
 984         protected static function safeFileHash( $filePath ) {
 985                 return FileContentsHasher::getFileContentsHash( $filePath );
 986         }
 987 }