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