includes/resourceloader/ResourceLoaderModule.php

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