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