includes/filebackend/FileBackendMultiWrite.php

   1 <?php
   2 /**
   3  * Proxy backend that mirrors writes to several internal backends.
   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  * @ingroup FileBackend
  22  * @author Aaron Schulz
  23  */
  24
  25 /**
  26  * @brief Proxy backend that mirrors writes to several internal backends.
  27  *
  28  * This class defines a multi-write backend. Multiple backends can be
  29  * registered to this proxy backend and it will act as a single backend.
  30  * Use this when all access to those backends is through this proxy backend.
  31  * At least one of the backends must be declared the "master" backend.
  32  *
  33  * Only use this class when transitioning from one storage system to another.
  34  *
  35  * Read operations are only done on the 'master' backend for consistency.
  36  * Write operations are performed on all backends, in the order defined.
  37  * If an operation fails on one backend it will be rolled back from the others.
  38  *
  39  * @ingroup FileBackend
  40  * @since 1.19
  41  */
  42 class FileBackendMultiWrite extends FileBackend {
  43         /** @var array Prioritized list of FileBackendStore objects.
  44          * array of (backend index => backends)
  45          */
  46         protected $backends = array();
  47
  48         /** @var int Index of master backend */
  49         protected $masterIndex = -1;
  50
  51         /** @var int Bitfield */
  52         protected $syncChecks = 0;
  53
  54         /** @var string|bool */
  55         protected $autoResync = false;
  56
  57         /** @var array */
  58         protected $noPushDirConts = array();
  59
  60         /** @var bool */
  61         protected $noPushQuickOps = false;
  62
  63         /* Possible internal backend consistency checks */
  64         const CHECK_SIZE = 1;
  65         const CHECK_TIME = 2;
  66         const CHECK_SHA1 = 4;
  67
  68         /**
  69          * Construct a proxy backend that consists of several internal backends.
  70          * Locking, journaling, and read-only checks are handled by the proxy backend.
  71          *
  72          * Additional $config params include:
  73          *   - backends       : Array of backend config and multi-backend settings.
  74          *                      Each value is the config used in the constructor of a
  75          *                      FileBackendStore class, but with these additional settings:
  76          *                        - class         : The name of the backend class
  77          *                        - isMultiMaster : This must be set for one backend.
  78          *                        - template:     : If given a backend name, this will use
  79          *                                          the config of that backend as a template.
  80          *                                          Values specified here take precedence.
  81          *   - syncChecks     : Integer bitfield of internal backend sync checks to perform.
  82          *                      Possible bits include the FileBackendMultiWrite::CHECK_* constants.
  83          *                      There are constants for SIZE, TIME, and SHA1.
  84          *                      The checks are done before allowing any file operations.
  85          *   - autoResync     : Automatically resync the clone backends to the master backend
  86          *                      when pre-operation sync checks fail. This should only be used
  87          *                      if the master backend is stable and not missing any files.
  88          *                      Use "conservative" to limit resyncing to copying newer master
  89          *                      backend files over older (or non-existing) clone backend files.
  90          *                      Cases that cannot be handled will result in operation abortion.
  91          *   - noPushQuickOps : (hack) Only apply doQuickOperations() to the master backend.
  92          *   - noPushDirConts : (hack) Only apply directory functions to the master backend.
  93          *
  94          * @param array $config
  95          * @throws FileBackendError
  96          */
  97         public function __construct( array $config ) {
  98                 parent::__construct( $config );
  99                 $this->syncChecks = isset( $config['syncChecks'] )
 100                         ? $config['syncChecks']
 101                         : self::CHECK_SIZE;
 102                 $this->autoResync = isset( $config['autoResync'] )
 103                         ? $config['autoResync']
 104                         : false;
 105                 $this->noPushQuickOps = isset( $config['noPushQuickOps'] )
 106                         ? $config['noPushQuickOps']
 107                         : false;
 108                 $this->noPushDirConts = isset( $config['noPushDirConts'] )
 109                         ? $config['noPushDirConts']
 110                         : array();
 111                 // Construct backends here rather than via registration
 112                 // to keep these backends hidden from outside the proxy.
 113                 $namesUsed = array();
 114                 foreach ( $config['backends'] as $index => $config ) {
 115                         if ( isset( $config['template'] ) ) {
 116                                 // Config is just a modified version of a registered backend's.
 117                                 // This should only be used when that config is used only by this backend.
 118                                 $config = $config + FileBackendGroup::singleton()->config( $config['template'] );
 119                         }
 120                         $name = $config['name'];
 121                         if ( isset( $namesUsed[$name] ) ) { // don't break FileOp predicates
 122                                 throw new FileBackendError( "Two or more backends defined with the name $name." );
 123                         }
 124                         $namesUsed[$name] = 1;
 125                         // Alter certain sub-backend settings for sanity
 126                         unset( $config['readOnly'] ); // use proxy backend setting
 127                         unset( $config['fileJournal'] ); // use proxy backend journal
 128                         unset( $config['lockManager'] ); // lock under proxy backend
 129                         $config['wikiId'] = $this->wikiId; // use the proxy backend wiki ID
 130                         if ( !empty( $config['isMultiMaster'] ) ) {
 131                                 if ( $this->masterIndex >= 0 ) {
 132                                         throw new FileBackendError( 'More than one master backend defined.' );
 133                                 }
 134                                 $this->masterIndex = $index; // this is the "master"
 135                                 $config['fileJournal'] = $this->fileJournal; // log under proxy backend
 136                         }
 137                         // Create sub-backend object
 138                         if ( !isset( $config['class'] ) ) {
 139                                 throw new FileBackendError( 'No class given for a backend config.' );
 140                         }
 141                         $class = $config['class'];
 142                         $this->backends[$index] = new $class( $config );
 143                 }
 144                 if ( $this->masterIndex < 0 ) { // need backends and must have a master
 145                         throw new FileBackendError( 'No master backend defined.' );
 146                 }
 147         }
 148
 149         final protected function doOperationsInternal( array $ops, array $opts ) {
 150                 $status = Status::newGood();
 151
 152                 $mbe = $this->backends[$this->masterIndex]; // convenience
 153
 154                 // Try to lock those files for the scope of this function...
 155                 if ( empty( $opts['nonLocking'] ) ) {
 156                         // Try to lock those files for the scope of this function...
 157                         $scopeLock = $this->getScopedLocksForOps( $ops, $status );
 158                         if ( !$status->isOK() ) {
 159                                 return $status; // abort
 160                         }
 161                 }
 162                 // Clear any cache entries (after locks acquired)
 163                 $this->clearCache();
 164                 $opts['preserveCache'] = true; // only locked files are cached
 165                 // Get the list of paths to read/write...
 166                 $relevantPaths = $this->fileStoragePathsForOps( $ops );
 167                 // Check if the paths are valid and accessible on all backends...
 168                 $status->merge( $this->accessibilityCheck( $relevantPaths ) );
 169                 if ( !$status->isOK() ) {
 170                         return $status; // abort
 171                 }
 172                 // Do a consistency check to see if the backends are consistent...
 173                 $syncStatus = $this->consistencyCheck( $relevantPaths );
 174                 if ( !$syncStatus->isOK() ) {
 175                         wfDebugLog( 'FileOperation', get_class( $this ) .
 176                                 " failed sync check: " . FormatJson::encode( $relevantPaths ) );
 177                         // Try to resync the clone backends to the master on the spot...
 178                         if ( !$this->autoResync || !$this->resyncFiles( $relevantPaths )->isOK() ) {
 179                                 $status->merge( $syncStatus );
 180
 181                                 return $status; // abort
 182                         }
 183                 }
 184                 // Actually attempt the operation batch on the master backend...
 185                 $realOps = $this->substOpBatchPaths( $ops, $mbe );
 186                 $masterStatus = $mbe->doOperations( $realOps, $opts );
 187                 $status->merge( $masterStatus );
 188                 // Propagate the operations to the clone backends if there were no unexpected errors
 189                 // and if there were either no expected errors or if the 'force' option was used.
 190                 // However, if nothing succeeded at all, then don't replicate any of the operations.
 191                 // If $ops only had one operation, this might avoid backend sync inconsistencies.
 192                 if ( $masterStatus->isOK() && $masterStatus->successCount > 0 ) {
 193                         foreach ( $this->backends as $index => $backend ) {
 194                                 if ( $index !== $this->masterIndex ) { // not done already
 195                                         $realOps = $this->substOpBatchPaths( $ops, $backend );
 196                                         $status->merge( $backend->doOperations( $realOps, $opts ) );
 197                                 }
 198                         }
 199                 }
 200                 // Make 'success', 'successCount', and 'failCount' fields reflect
 201                 // the overall operation, rather than all the batches for each backend.
 202                 // Do this by only using success values from the master backend's batch.
 203                 $status->success = $masterStatus->success;
 204                 $status->successCount = $masterStatus->successCount;
 205                 $status->failCount = $masterStatus->failCount;
 206
 207                 return $status;
 208         }
 209
 210         /**
 211          * Check that a set of files are consistent across all internal backends
 212          *
 213          * @param array $paths List of storage paths
 214          * @return Status
 215          */
 216         public function consistencyCheck( array $paths ) {
 217                 $status = Status::newGood();
 218                 if ( $this->syncChecks == 0 || count( $this->backends ) <= 1 ) {
 219                         return $status; // skip checks
 220                 }
 221
 222                 $mBackend = $this->backends[$this->masterIndex];
 223                 foreach ( $paths as $path ) {
 224                         $params = array( 'src' => $path, 'latest' => true );
 225                         $mParams = $this->substOpPaths( $params, $mBackend );
 226                         // Stat the file on the 'master' backend
 227                         $mStat = $mBackend->getFileStat( $mParams );
 228                         if ( $this->syncChecks & self::CHECK_SHA1 ) {
 229                                 $mSha1 = $mBackend->getFileSha1Base36( $mParams );
 230                         } else {
 231                                 $mSha1 = false;
 232                         }
 233                         // Check if all clone backends agree with the master...
 234                         foreach ( $this->backends as $index => $cBackend ) {
 235                                 if ( $index === $this->masterIndex ) {
 236                                         continue; // master
 237                                 }
 238                                 $cParams = $this->substOpPaths( $params, $cBackend );
 239                                 $cStat = $cBackend->getFileStat( $cParams );
 240                                 if ( $mStat ) { // file is in master
 241                                         if ( !$cStat ) { // file should exist
 242                                                 $status->fatal( 'backend-fail-synced', $path );
 243                                                 continue;
 244                                         }
 245                                         if ( $this->syncChecks & self::CHECK_SIZE ) {
 246                                                 if ( $cStat['size'] != $mStat['size'] ) { // wrong size
 247                                                         $status->fatal( 'backend-fail-synced', $path );
 248                                                         continue;
 249                                                 }
 250                                         }
 251                                         if ( $this->syncChecks & self::CHECK_TIME ) {
 252                                                 $mTs = wfTimestamp( TS_UNIX, $mStat['mtime'] );
 253                                                 $cTs = wfTimestamp( TS_UNIX, $cStat['mtime'] );
 254                                                 if ( abs( $mTs - $cTs ) > 30 ) { // outdated file somewhere
 255                                                         $status->fatal( 'backend-fail-synced', $path );
 256                                                         continue;
 257                                                 }
 258                                         }
 259                                         if ( $this->syncChecks & self::CHECK_SHA1 ) {
 260                                                 if ( $cBackend->getFileSha1Base36( $cParams ) !== $mSha1 ) { // wrong SHA1
 261                                                         $status->fatal( 'backend-fail-synced', $path );
 262                                                         continue;
 263                                                 }
 264                                         }
 265                                 } else { // file is not in master
 266                                         if ( $cStat ) { // file should not exist
 267                                                 $status->fatal( 'backend-fail-synced', $path );
 268                                         }
 269                                 }
 270                         }
 271                 }
 272
 273                 return $status;
 274         }
 275
 276         /**
 277          * Check that a set of file paths are usable across all internal backends
 278          *
 279          * @param array $paths List of storage paths
 280          * @return Status
 281          */
 282         public function accessibilityCheck( array $paths ) {
 283                 $status = Status::newGood();
 284                 if ( count( $this->backends ) <= 1 ) {
 285                         return $status; // skip checks
 286                 }
 287
 288                 foreach ( $paths as $path ) {
 289                         foreach ( $this->backends as $backend ) {
 290                                 $realPath = $this->substPaths( $path, $backend );
 291                                 if ( !$backend->isPathUsableInternal( $realPath ) ) {
 292                                         $status->fatal( 'backend-fail-usable', $path );
 293                                 }
 294                         }
 295                 }
 296
 297                 return $status;
 298         }
 299
 300         /**
 301          * Check that a set of files are consistent across all internal backends
 302          * and re-synchronize those files againt the "multi master" if needed.
 303          *
 304          * @param array $paths List of storage paths
 305          * @return Status
 306          */
 307         public function resyncFiles( array $paths ) {
 308                 $status = Status::newGood();
 309
 310                 $mBackend = $this->backends[$this->masterIndex];
 311                 foreach ( $paths as $path ) {
 312                         $mPath = $this->substPaths( $path, $mBackend );
 313                         $mSha1 = $mBackend->getFileSha1Base36( array( 'src' => $mPath, 'latest' => true ) );
 314                         $mStat = $mBackend->getFileStat( array( 'src' => $mPath, 'latest' => true ) );
 315                         if ( $mStat === null || ( $mSha1 !== false && !$mStat ) ) { // sanity
 316                                 $status->fatal( 'backend-fail-internal', $this->name );
 317                                 continue; // file is not available on the master backend...
 318                         }
 319                         // Check of all clone backends agree with the master...
 320                         foreach ( $this->backends as $index => $cBackend ) {
 321                                 if ( $index === $this->masterIndex ) {
 322                                         continue; // master
 323                                 }
 324                                 $cPath = $this->substPaths( $path, $cBackend );
 325                                 $cSha1 = $cBackend->getFileSha1Base36( array( 'src' => $cPath, 'latest' => true ) );
 326                                 $cStat = $cBackend->getFileStat( array( 'src' => $cPath, 'latest' => true ) );
 327                                 if ( $cStat === null || ( $cSha1 !== false && !$cStat ) ) { // sanity
 328                                         $status->fatal( 'backend-fail-internal', $cBackend->getName() );
 329                                         continue; // file is not available on the clone backend...
 330                                 }
 331                                 if ( $mSha1 === $cSha1 ) {
 332                                         // already synced; nothing to do
 333                                 } elseif ( $mSha1 !== false ) { // file is in master
 334                                         if ( $this->autoResync === 'conservative'
 335                                                 && $cStat && $cStat['mtime'] > $mStat['mtime']
 336                                         ) {
 337                                                 $status->fatal( 'backend-fail-synced', $path );
 338                                                 continue; // don't rollback data
 339                                         }
 340                                         $fsFile = $mBackend->getLocalReference(
 341                                                 array( 'src' => $mPath, 'latest' => true ) );
 342                                         $status->merge( $cBackend->quickStore(
 343                                                 array( 'src' => $fsFile->getPath(), 'dst' => $cPath )
 344                                         ) );
 345                                 } elseif ( $mStat === false ) { // file is not in master
 346                                         if ( $this->autoResync === 'conservative' ) {
 347                                                 $status->fatal( 'backend-fail-synced', $path );
 348                                                 continue; // don't delete data
 349                                         }
 350                                         $status->merge( $cBackend->quickDelete( array( 'src' => $cPath ) ) );
 351                                 }
 352                         }
 353                 }
 354
 355                 return $status;
 356         }
 357
 358         /**
 359          * Get a list of file storage paths to read or write for a list of operations
 360          *
 361          * @param array $ops Same format as doOperations()
 362          * @return array List of storage paths to files (does not include directories)
 363          */
 364         protected function fileStoragePathsForOps( array $ops ) {
 365                 $paths = array();
 366                 foreach ( $ops as $op ) {
 367                         if ( isset( $op['src'] ) ) {
 368                                 // For things like copy/move/delete with "ignoreMissingSource" and there
 369                                 // is no source file, nothing should happen and there should be no errors.
 370                                 if ( empty( $op['ignoreMissingSource'] )
 371                                         || $this->fileExists( array( 'src' => $op['src'] ) )
 372                                 ) {
 373                                         $paths[] = $op['src'];
 374                                 }
 375                         }
 376                         if ( isset( $op['srcs'] ) ) {
 377                                 $paths = array_merge( $paths, $op['srcs'] );
 378                         }
 379                         if ( isset( $op['dst'] ) ) {
 380                                 $paths[] = $op['dst'];
 381                         }
 382                 }
 383
 384                 return array_values( array_unique( array_filter( $paths, 'FileBackend::isStoragePath' ) ) );
 385         }
 386
 387         /**
 388          * Substitute the backend name in storage path parameters
 389          * for a set of operations with that of a given internal backend.
 390          *
 391          * @param array $ops List of file operation arrays
 392          * @param FileBackendStore $backend
 393          * @return array
 394          */
 395         protected function substOpBatchPaths( array $ops, FileBackendStore $backend ) {
 396                 $newOps = array(); // operations
 397                 foreach ( $ops as $op ) {
 398                         $newOp = $op; // operation
 399                         foreach ( array( 'src', 'srcs', 'dst', 'dir' ) as $par ) {
 400                                 if ( isset( $newOp[$par] ) ) { // string or array
 401                                         $newOp[$par] = $this->substPaths( $newOp[$par], $backend );
 402                                 }
 403                         }
 404                         $newOps[] = $newOp;
 405                 }
 406
 407                 return $newOps;
 408         }
 409
 410         /**
 411          * Same as substOpBatchPaths() but for a single operation
 412          *
 413          * @param array $ops File operation array
 414          * @param FileBackendStore $backend
 415          * @return array
 416          */
 417         protected function substOpPaths( array $ops, FileBackendStore $backend ) {
 418                 $newOps = $this->substOpBatchPaths( array( $ops ), $backend );
 419
 420                 return $newOps[0];
 421         }
 422
 423         /**
 424          * Substitute the backend of storage paths with an internal backend's name
 425          *
 426          * @param array|string $paths List of paths or single string path
 427          * @param FileBackendStore $backend
 428          * @return array|string
 429          */
 430         protected function substPaths( $paths, FileBackendStore $backend ) {
 431                 return preg_replace(
 432                         '!^mwstore://' . preg_quote( $this->name ) . '/!',
 433                         StringUtils::escapeRegexReplacement( "mwstore://{$backend->getName()}/" ),
 434                         $paths // string or array
 435                 );
 436         }
 437
 438         /**
 439          * Substitute the backend of internal storage paths with the proxy backend's name
 440          *
 441          * @param array|string $paths List of paths or single string path
 442          * @return array|string
 443          */
 444         protected function unsubstPaths( $paths ) {
 445                 return preg_replace(
 446                         '!^mwstore://([^/]+)!',
 447                         StringUtils::escapeRegexReplacement( "mwstore://{$this->name}" ),
 448                         $paths // string or array
 449                 );
 450         }
 451
 452         protected function doQuickOperationsInternal( array $ops ) {
 453                 $status = Status::newGood();
 454                 // Do the operations on the master backend; setting Status fields...
 455                 $realOps = $this->substOpBatchPaths( $ops, $this->backends[$this->masterIndex] );
 456                 $masterStatus = $this->backends[$this->masterIndex]->doQuickOperations( $realOps );
 457                 $status->merge( $masterStatus );
 458                 // Propagate the operations to the clone backends...
 459                 if ( !$this->noPushQuickOps ) {
 460                         foreach ( $this->backends as $index => $backend ) {
 461                                 if ( $index !== $this->masterIndex ) { // not done already
 462                                         $realOps = $this->substOpBatchPaths( $ops, $backend );
 463                                         $status->merge( $backend->doQuickOperations( $realOps ) );
 464                                 }
 465                         }
 466                 }
 467                 // Make 'success', 'successCount', and 'failCount' fields reflect
 468                 // the overall operation, rather than all the batches for each backend.
 469                 // Do this by only using success values from the master backend's batch.
 470                 $status->success = $masterStatus->success;
 471                 $status->successCount = $masterStatus->successCount;
 472                 $status->failCount = $masterStatus->failCount;
 473
 474                 return $status;
 475         }
 476
 477         /**
 478          * @param string $path Storage path
 479          * @return bool Path container should have dir changes pushed to all backends
 480          */
 481         protected function replicateContainerDirChanges( $path ) {
 482                 list( , $shortCont, ) = self::splitStoragePath( $path );
 483
 484                 return !in_array( $shortCont, $this->noPushDirConts );
 485         }
 486
 487         protected function doPrepare( array $params ) {
 488                 $status = Status::newGood();
 489                 $replicate = $this->replicateContainerDirChanges( $params['dir'] );
 490                 foreach ( $this->backends as $index => $backend ) {
 491                         if ( $replicate || $index == $this->masterIndex ) {
 492                                 $realParams = $this->substOpPaths( $params, $backend );
 493                                 $status->merge( $backend->doPrepare( $realParams ) );
 494                         }
 495                 }
 496
 497                 return $status;
 498         }
 499
 500         protected function doSecure( array $params ) {
 501                 $status = Status::newGood();
 502                 $replicate = $this->replicateContainerDirChanges( $params['dir'] );
 503                 foreach ( $this->backends as $index => $backend ) {
 504                         if ( $replicate || $index == $this->masterIndex ) {
 505                                 $realParams = $this->substOpPaths( $params, $backend );
 506                                 $status->merge( $backend->doSecure( $realParams ) );
 507                         }
 508                 }
 509
 510                 return $status;
 511         }
 512
 513         protected function doPublish( array $params ) {
 514                 $status = Status::newGood();
 515                 $replicate = $this->replicateContainerDirChanges( $params['dir'] );
 516                 foreach ( $this->backends as $index => $backend ) {
 517                         if ( $replicate || $index == $this->masterIndex ) {
 518                                 $realParams = $this->substOpPaths( $params, $backend );
 519                                 $status->merge( $backend->doPublish( $realParams ) );
 520                         }
 521                 }
 522
 523                 return $status;
 524         }
 525
 526         protected function doClean( array $params ) {
 527                 $status = Status::newGood();
 528                 $replicate = $this->replicateContainerDirChanges( $params['dir'] );
 529                 foreach ( $this->backends as $index => $backend ) {
 530                         if ( $replicate || $index == $this->masterIndex ) {
 531                                 $realParams = $this->substOpPaths( $params, $backend );
 532                                 $status->merge( $backend->doClean( $realParams ) );
 533                         }
 534                 }
 535
 536                 return $status;
 537         }
 538
 539         public function concatenate( array $params ) {
 540                 // We are writing to an FS file, so we don't need to do this per-backend
 541                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 542
 543                 return $this->backends[$this->masterIndex]->concatenate( $realParams );
 544         }
 545
 546         public function fileExists( array $params ) {
 547                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 548
 549                 return $this->backends[$this->masterIndex]->fileExists( $realParams );
 550         }
 551
 552         public function getFileTimestamp( array $params ) {
 553                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 554
 555                 return $this->backends[$this->masterIndex]->getFileTimestamp( $realParams );
 556         }
 557
 558         public function getFileSize( array $params ) {
 559                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 560
 561                 return $this->backends[$this->masterIndex]->getFileSize( $realParams );
 562         }
 563
 564         public function getFileStat( array $params ) {
 565                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 566
 567                 return $this->backends[$this->masterIndex]->getFileStat( $realParams );
 568         }
 569
 570         public function getFileXAttributes( array $params ) {
 571                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 572
 573                 return $this->backends[$this->masterIndex]->getFileXAttributes( $realParams );
 574         }
 575
 576         public function getFileContentsMulti( array $params ) {
 577                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 578                 $contentsM = $this->backends[$this->masterIndex]->getFileContentsMulti( $realParams );
 579
 580                 $contents = array(); // (path => FSFile) mapping using the proxy backend's name
 581                 foreach ( $contentsM as $path => $data ) {
 582                         $contents[$this->unsubstPaths( $path )] = $data;
 583                 }
 584
 585                 return $contents;
 586         }
 587
 588         public function getFileSha1Base36( array $params ) {
 589                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 590
 591                 return $this->backends[$this->masterIndex]->getFileSha1Base36( $realParams );
 592         }
 593
 594         public function getFileProps( array $params ) {
 595                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 596
 597                 return $this->backends[$this->masterIndex]->getFileProps( $realParams );
 598         }
 599
 600         public function streamFile( array $params ) {
 601                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 602
 603                 return $this->backends[$this->masterIndex]->streamFile( $realParams );
 604         }
 605
 606         public function getLocalReferenceMulti( array $params ) {
 607                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 608                 $fsFilesM = $this->backends[$this->masterIndex]->getLocalReferenceMulti( $realParams );
 609
 610                 $fsFiles = array(); // (path => FSFile) mapping using the proxy backend's name
 611                 foreach ( $fsFilesM as $path => $fsFile ) {
 612                         $fsFiles[$this->unsubstPaths( $path )] = $fsFile;
 613                 }
 614
 615                 return $fsFiles;
 616         }
 617
 618         public function getLocalCopyMulti( array $params ) {
 619                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 620                 $tempFilesM = $this->backends[$this->masterIndex]->getLocalCopyMulti( $realParams );
 621
 622                 $tempFiles = array(); // (path => TempFSFile) mapping using the proxy backend's name
 623                 foreach ( $tempFilesM as $path => $tempFile ) {
 624                         $tempFiles[$this->unsubstPaths( $path )] = $tempFile;
 625                 }
 626
 627                 return $tempFiles;
 628         }
 629
 630         public function getFileHttpUrl( array $params ) {
 631                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 632
 633                 return $this->backends[$this->masterIndex]->getFileHttpUrl( $realParams );
 634         }
 635
 636         public function directoryExists( array $params ) {
 637                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 638
 639                 return $this->backends[$this->masterIndex]->directoryExists( $realParams );
 640         }
 641
 642         public function getDirectoryList( array $params ) {
 643                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 644
 645                 return $this->backends[$this->masterIndex]->getDirectoryList( $realParams );
 646         }
 647
 648         public function getFileList( array $params ) {
 649                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 650
 651                 return $this->backends[$this->masterIndex]->getFileList( $realParams );
 652         }
 653
 654         public function getFeatures() {
 655                 return $this->backends[$this->masterIndex]->getFeatures();
 656         }
 657
 658         public function clearCache( array $paths = null ) {
 659                 foreach ( $this->backends as $backend ) {
 660                         $realPaths = is_array( $paths ) ? $this->substPaths( $paths, $backend ) : null;
 661                         $backend->clearCache( $realPaths );
 662                 }
 663         }
 664
 665         public function preloadCache( array $paths ) {
 666                 $realPaths = $this->substPaths( $paths, $this->backends[$this->masterIndex] );
 667                 $this->backends[$this->masterIndex]->preloadCache( $realPaths );
 668         }
 669
 670         public function preloadFileStat( array $params ) {
 671                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 672                 return $this->backends[$this->masterIndex]->preloadFileStat( $realParams );
 673         }
 674
 675         public function getScopedLocksForOps( array $ops, Status $status ) {
 676                 $realOps = $this->substOpBatchPaths( $ops, $this->backends[$this->masterIndex] );
 677                 $fileOps = $this->backends[$this->masterIndex]->getOperationsInternal( $realOps );
 678                 // Get the paths to lock from the master backend
 679                 $paths = $this->backends[$this->masterIndex]->getPathsToLockForOpsInternal( $fileOps );
 680                 // Get the paths under the proxy backend's name
 681                 $pbPaths = array(
 682                         LockManager::LOCK_UW => $this->unsubstPaths( $paths[LockManager::LOCK_UW] ),
 683                         LockManager::LOCK_EX => $this->unsubstPaths( $paths[LockManager::LOCK_EX] )
 684                 );
 685
 686                 // Actually acquire the locks
 687                 return array( $this->getScopedFileLocks( $pbPaths, 'mixed', $status ) );
 688         }
 689 }