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