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         protected $backends = array(); // array of (backend index => backends)
  45         protected $masterIndex = -1; // integer; index of master backend
  46         protected $syncChecks = 0; // integer; bitfield
  47         protected $autoResync = false; // boolean
  48
  49         /** @var Array */
  50         protected $noPushDirConts = array();
  51         protected $noPushQuickOps = false; // boolean
  52
  53         /* Possible internal backend consistency checks */
  54         const CHECK_SIZE = 1;
  55         const CHECK_TIME = 2;
  56         const CHECK_SHA1 = 4;
  57
  58         /**
  59          * Construct a proxy backend that consists of several internal backends.
  60          * Locking, journaling, and read-only checks are handled by the proxy backend.
  61          *
  62          * Additional $config params include:
  63          *   - backends       : Array of backend config and multi-backend settings.
  64          *                      Each value is the config used in the constructor of a
  65          *                      FileBackendStore class, but with these additional settings:
  66          *                        - class         : The name of the backend class
  67          *                        - isMultiMaster : This must be set for one backend.
  68          *                        - template:     : If given a backend name, this will use
  69          *                                          the config of that backend as a template.
  70          *                                          Values specified here take precedence.
  71          *   - syncChecks     : Integer bitfield of internal backend sync checks to perform.
  72          *                      Possible bits include the FileBackendMultiWrite::CHECK_* constants.
  73          *                      There are constants for SIZE, TIME, and SHA1.
  74          *                      The checks are done before allowing any file operations.
  75          *   - autoResync     : Automatically resync the clone backends to the master backend
  76          *                      when pre-operation sync checks fail. This should only be used
  77          *                      if the master backend is stable and not missing any files.
  78          *                      Use "conservative" to limit resyncing to copying newer master
  79          *                      backend files over older (or non-existing) clone backend files.
  80          *                      Cases that cannot be handled will result in operation abortion.
  81          *   - noPushQuickOps : (hack) Only apply doQuickOperations() to the master backend.
  82          *   - noPushDirConts : (hack) Only apply directory functions to the master backend.
  83          *
  84          * @param Array $config
  85          * @throws MWException
  86          */
  87         public function __construct( array $config ) {
  88                 parent::__construct( $config );
  89                 $this->syncChecks = isset( $config['syncChecks'] )
  90                         ? $config['syncChecks']
  91                         : self::CHECK_SIZE;
  92                 $this->autoResync = isset( $config['autoResync'] )
  93                         ? $config['autoResync']
  94                         : false;
  95                 $this->noPushQuickOps = isset( $config['noPushQuickOps'] )
  96                         ? $config['noPushQuickOps']
  97                         : false;
  98                 $this->noPushDirConts = isset( $config['noPushDirConts'] )
  99                         ? $config['noPushDirConts']
 100                         : array();
 101                 // Construct backends here rather than via registration
 102                 // to keep these backends hidden from outside the proxy.
 103                 $namesUsed = array();
 104                 foreach ( $config['backends'] as $index => $config ) {
 105                         if ( isset( $config['template'] ) ) {
 106                                 // Config is just a modified version of a registered backend's.
 107                                 // This should only be used when that config is used only by this backend.
 108                                 $config = $config + FileBackendGroup::singleton()->config( $config['template'] );
 109                         }
 110                         $name = $config['name'];
 111                         if ( isset( $namesUsed[$name] ) ) { // don't break FileOp predicates
 112                                 throw new MWException( "Two or more backends defined with the name $name." );
 113                         }
 114                         $namesUsed[$name] = 1;
 115                         // Alter certain sub-backend settings for sanity
 116                         unset( $config['readOnly'] ); // use proxy backend setting
 117                         unset( $config['fileJournal'] ); // use proxy backend journal
 118                         $config['wikiId'] = $this->wikiId; // use the proxy backend wiki ID
 119                         $config['lockManager'] = 'nullLockManager'; // lock under proxy backend
 120                         if ( !empty( $config['isMultiMaster'] ) ) {
 121                                 if ( $this->masterIndex >= 0 ) {
 122                                         throw new MWException( 'More than one master backend defined.' );
 123                                 }
 124                                 $this->masterIndex = $index; // this is the "master"
 125                                 $config['fileJournal'] = $this->fileJournal; // log under proxy backend
 126                         }
 127                         // Create sub-backend object
 128                         if ( !isset( $config['class'] ) ) {
 129                                 throw new MWException( 'No class given for a backend config.' );
 130                         }
 131                         $class = $config['class'];
 132                         $this->backends[$index] = new $class( $config );
 133                 }
 134                 if ( $this->masterIndex < 0 ) { // need backends and must have a master
 135                         throw new MWException( 'No master backend defined.' );
 136                 }
 137         }
 138
 139         /**
 140          * @see FileBackend::doOperationsInternal()
 141          * @return Status
 142          */
 143         final protected function doOperationsInternal( array $ops, array $opts ) {
 144                 $status = Status::newGood();
 145
 146                 $mbe = $this->backends[$this->masterIndex]; // convenience
 147
 148                 // Get the paths to lock from the master backend
 149                 $realOps = $this->substOpBatchPaths( $ops, $mbe );
 150                 $paths = $mbe->getPathsToLockForOpsInternal( $mbe->getOperationsInternal( $realOps ) );
 151                 // Get the paths under the proxy backend's name
 152                 $paths['sh'] = $this->unsubstPaths( $paths['sh'] );
 153                 $paths['ex'] = $this->unsubstPaths( $paths['ex'] );
 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                         $scopeLockS = $this->getScopedFileLocks( $paths['sh'], LockManager::LOCK_UW, $status );
 158                         $scopeLockE = $this->getScopedFileLocks( $paths['ex'], LockManager::LOCK_EX, $status );
 159                         if ( !$status->isOK() ) {
 160                                 return $status; // abort
 161                         }
 162                 }
 163                 // Clear any cache entries (after locks acquired)
 164                 $this->clearCache();
 165                 $opts['preserveCache'] = true; // only locked files are cached
 166                 // Get the list of paths to read/write...
 167                 $relevantPaths = $this->fileStoragePathsForOps( $ops );
 168                 // Check if the paths are valid and accessible on all backends...
 169                 $status->merge( $this->accessibilityCheck( $relevantPaths ) );
 170                 if ( !$status->isOK() ) {
 171                         return $status; // abort
 172                 }
 173                 // Do a consistency check to see if the backends are consistent...
 174                 $syncStatus = $this->consistencyCheck( $relevantPaths );
 175                 if ( !$syncStatus->isOK() ) {
 176                         wfDebugLog( 'FileOperation', get_class( $this ) .
 177                                 " failed sync check: " . FormatJson::encode( $relevantPaths ) );
 178                         // Try to resync the clone backends to the master on the spot...
 179                         if ( !$this->autoResync || !$this->resyncFiles( $relevantPaths )->isOK() ) {
 180                                 $status->merge( $syncStatus );
 181                                 return $status; // abort
 182                         }
 183                 }
 184                 // Actually attempt the operation batch on the master backend...
 185                 $masterStatus = $mbe->doOperations( $realOps, $opts );
 186                 $status->merge( $masterStatus );
 187                 // Propagate the operations to the clone backends if there were no unexpected errors
 188                 // and if there were either no expected errors or if the 'force' option was used.
 189                 // However, if nothing succeeded at all, then don't replicate any of the operations.
 190                 // If $ops only had one operation, this might avoid backend sync inconsistencies.
 191                 if ( $masterStatus->isOK() && $masterStatus->successCount > 0 ) {
 192                         foreach ( $this->backends as $index => $backend ) {
 193                                 if ( $index !== $this->masterIndex ) { // not done already
 194                                         $realOps = $this->substOpBatchPaths( $ops, $backend );
 195                                         $status->merge( $backend->doOperations( $realOps, $opts ) );
 196                                 }
 197                         }
 198                 }
 199                 // Make 'success', 'successCount', and 'failCount' fields reflect
 200                 // the overall operation, rather than all the batches for each backend.
 201                 // Do this by only using success values from the master backend's batch.
 202                 $status->success = $masterStatus->success;
 203                 $status->successCount = $masterStatus->successCount;
 204                 $status->failCount = $masterStatus->failCount;
 205
 206                 return $status;
 207         }
 208
 209         /**
 210          * Check that a set of files are consistent across all internal backends
 211          *
 212          * @param array $paths List of storage paths
 213          * @return Status
 214          */
 215         public function consistencyCheck( array $paths ) {
 216                 $status = Status::newGood();
 217                 if ( $this->syncChecks == 0 || count( $this->backends ) <= 1 ) {
 218                         return $status; // skip checks
 219                 }
 220
 221                 $mBackend = $this->backends[$this->masterIndex];
 222                 foreach ( $paths as $path ) {
 223                         $params = array( 'src' => $path, 'latest' => true );
 224                         $mParams = $this->substOpPaths( $params, $mBackend );
 225                         // Stat the file on the 'master' backend
 226                         $mStat = $mBackend->getFileStat( $mParams );
 227                         if ( $this->syncChecks & self::CHECK_SHA1 ) {
 228                                 $mSha1 = $mBackend->getFileSha1Base36( $mParams );
 229                         } else {
 230                                 $mSha1 = false;
 231                         }
 232                         // Check if all clone backends agree with the master...
 233                         foreach ( $this->backends as $index => $cBackend ) {
 234                                 if ( $index === $this->masterIndex ) {
 235                                         continue; // master
 236                                 }
 237                                 $cParams = $this->substOpPaths( $params, $cBackend );
 238                                 $cStat = $cBackend->getFileStat( $cParams );
 239                                 if ( $mStat ) { // file is in master
 240                                         if ( !$cStat ) { // file should exist
 241                                                 $status->fatal( 'backend-fail-synced', $path );
 242                                                 continue;
 243                                         }
 244                                         if ( $this->syncChecks & self::CHECK_SIZE ) {
 245                                                 if ( $cStat['size'] != $mStat['size'] ) { // wrong size
 246                                                         $status->fatal( 'backend-fail-synced', $path );
 247                                                         continue;
 248                                                 }
 249                                         }
 250                                         if ( $this->syncChecks & self::CHECK_TIME ) {
 251                                                 $mTs = wfTimestamp( TS_UNIX, $mStat['mtime'] );
 252                                                 $cTs = wfTimestamp( TS_UNIX, $cStat['mtime'] );
 253                                                 if ( abs( $mTs - $cTs ) > 30 ) { // outdated file somewhere
 254                                                         $status->fatal( 'backend-fail-synced', $path );
 255                                                         continue;
 256                                                 }
 257                                         }
 258                                         if ( $this->syncChecks & self::CHECK_SHA1 ) {
 259                                                 if ( $cBackend->getFileSha1Base36( $cParams ) !== $mSha1 ) { // wrong SHA1
 260                                                         $status->fatal( 'backend-fail-synced', $path );
 261                                                         continue;
 262                                                 }
 263                                         }
 264                                 } else { // file is not in master
 265                                         if ( $cStat ) { // file should not exist
 266                                                 $status->fatal( 'backend-fail-synced', $path );
 267                                         }
 268                                 }
 269                         }
 270                 }
 271
 272                 return $status;
 273         }
 274
 275         /**
 276          * Check that a set of file paths are usable across all internal backends
 277          *
 278          * @param array $paths List of storage paths
 279          * @return Status
 280          */
 281         public function accessibilityCheck( array $paths ) {
 282                 $status = Status::newGood();
 283                 if ( count( $this->backends ) <= 1 ) {
 284                         return $status; // skip checks
 285                 }
 286
 287                 foreach ( $paths as $path ) {
 288                         foreach ( $this->backends as $backend ) {
 289                                 $realPath = $this->substPaths( $path, $backend );
 290                                 if ( !$backend->isPathUsableInternal( $realPath ) ) {
 291                                         $status->fatal( 'backend-fail-usable', $path );
 292                                 }
 293                         }
 294                 }
 295
 296                 return $status;
 297         }
 298
 299         /**
 300          * Check that a set of files are consistent across all internal backends
 301          * and re-synchronize those files againt the "multi master" if needed.
 302          *
 303          * @param array $paths List of storage paths
 304          * @return Status
 305          */
 306         public function resyncFiles( array $paths ) {
 307                 $status = Status::newGood();
 308
 309                 $mBackend = $this->backends[$this->masterIndex];
 310                 foreach ( $paths as $path ) {
 311                         $mPath = $this->substPaths( $path, $mBackend );
 312                         $mSha1 = $mBackend->getFileSha1Base36( array( 'src' => $mPath, 'latest' => true ) );
 313                         $mStat = $mBackend->getFileStat( array( 'src' => $mPath, 'latest' => true ) );
 314                         if ( $mStat === null || ( $mSha1 !== false && !$mStat ) ) { // sanity
 315                                 $status->fatal( 'backend-fail-internal', $this->name );
 316                                 continue; // file is not available on the master backend...
 317                         }
 318                         // Check of all clone backends agree with the master...
 319                         foreach ( $this->backends as $index => $cBackend ) {
 320                                 if ( $index === $this->masterIndex ) {
 321                                         continue; // master
 322                                 }
 323                                 $cPath = $this->substPaths( $path, $cBackend );
 324                                 $cSha1 = $cBackend->getFileSha1Base36( array( 'src' => $cPath, 'latest' => true ) );
 325                                 $cStat = $cBackend->getFileStat( array( 'src' => $cPath, 'latest' => true ) );
 326                                 if ( $cStat === null || ( $cSha1 !== false && !$cStat ) ) { // sanity
 327                                         $status->fatal( 'backend-fail-internal', $cBackend->getName() );
 328                                         continue; // file is not available on the clone backend...
 329                                 }
 330                                 if ( $mSha1 === $cSha1 ) {
 331                                         // already synced; nothing to do
 332                                 } elseif ( $mSha1 !== false ) { // file is in master
 333                                         if ( $this->autoResync === 'conservative'
 334                                                 && $cStat && $cStat['mtime'] > $mStat['mtime'] )
 335                                         {
 336                                                 $status->fatal( 'backend-fail-synced', $path );
 337                                                 continue; // don't rollback data
 338                                         }
 339                                         $fsFile = $mBackend->getLocalReference(
 340                                                 array( 'src' => $mPath, 'latest' => true ) );
 341                                         $status->merge( $cBackend->quickStore(
 342                                                 array( 'src' => $fsFile->getPath(), 'dst' => $cPath )
 343                                         ) );
 344                                 } elseif ( $mStat === false ) { // file is not in master
 345                                         if ( $this->autoResync === 'conservative' ) {
 346                                                 $status->fatal( 'backend-fail-synced', $path );
 347                                                 continue; // don't delete data
 348                                         }
 349                                         $status->merge( $cBackend->quickDelete( array( 'src' => $cPath ) ) );
 350                                 }
 351                         }
 352                 }
 353
 354                 return $status;
 355         }
 356
 357         /**
 358          * Get a list of file storage paths to read or write for a list of operations
 359          *
 360          * @param array $ops Same format as doOperations()
 361          * @return Array List of storage paths to files (does not include directories)
 362          */
 363         protected function fileStoragePathsForOps( array $ops ) {
 364                 $paths = array();
 365                 foreach ( $ops as $op ) {
 366                         if ( isset( $op['src'] ) ) {
 367                                 // For things like copy/move/delete with "ignoreMissingSource" and there
 368                                 // is no source file, nothing should happen and there should be no errors.
 369                                 if ( empty( $op['ignoreMissingSource'] )
 370                                         || $this->fileExists( array( 'src' => $op['src'] ) ) )
 371                                 {
 372                                         $paths[] = $op['src'];
 373                                 }
 374                         }
 375                         if ( isset( $op['srcs'] ) ) {
 376                                 $paths = array_merge( $paths, $op['srcs'] );
 377                         }
 378                         if ( isset( $op['dst'] ) ) {
 379                                 $paths[] = $op['dst'];
 380                         }
 381                 }
 382                 return array_values( array_unique( array_filter( $paths, 'FileBackend::isStoragePath' ) ) );
 383         }
 384
 385         /**
 386          * Substitute the backend name in storage path parameters
 387          * for a set of operations with that of a given internal backend.
 388          *
 389          * @param array $ops List of file operation arrays
 390          * @param FileBackendStore $backend
 391          * @return Array
 392          */
 393         protected function substOpBatchPaths( array $ops, FileBackendStore $backend ) {
 394                 $newOps = array(); // operations
 395                 foreach ( $ops as $op ) {
 396                         $newOp = $op; // operation
 397                         foreach ( array( 'src', 'srcs', 'dst', 'dir' ) as $par ) {
 398                                 if ( isset( $newOp[$par] ) ) { // string or array
 399                                         $newOp[$par] = $this->substPaths( $newOp[$par], $backend );
 400                                 }
 401                         }
 402                         $newOps[] = $newOp;
 403                 }
 404                 return $newOps;
 405         }
 406
 407         /**
 408          * Same as substOpBatchPaths() but for a single operation
 409          *
 410          * @param array $ops File operation array
 411          * @param FileBackendStore $backend
 412          * @return Array
 413          */
 414         protected function substOpPaths( array $ops, FileBackendStore $backend ) {
 415                 $newOps = $this->substOpBatchPaths( array( $ops ), $backend );
 416                 return $newOps[0];
 417         }
 418
 419         /**
 420          * Substitute the backend of storage paths with an internal backend's name
 421          *
 422          * @param array|string $paths List of paths or single string path
 423          * @param FileBackendStore $backend
 424          * @return Array|string
 425          */
 426         protected function substPaths( $paths, FileBackendStore $backend ) {
 427                 return preg_replace(
 428                         '!^mwstore://' . preg_quote( $this->name ) . '/!',
 429                         StringUtils::escapeRegexReplacement( "mwstore://{$backend->getName()}/" ),
 430                         $paths // string or array
 431                 );
 432         }
 433
 434         /**
 435          * Substitute the backend of internal storage paths with the proxy backend's name
 436          *
 437          * @param array|string $paths List of paths or single string path
 438          * @return Array|string
 439          */
 440         protected function unsubstPaths( $paths ) {
 441                 return preg_replace(
 442                         '!^mwstore://([^/]+)!',
 443                         StringUtils::escapeRegexReplacement( "mwstore://{$this->name}" ),
 444                         $paths // string or array
 445                 );
 446         }
 447
 448         /**
 449          * @see FileBackend::doQuickOperationsInternal()
 450          * @return Status
 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                 return $status;
 474         }
 475
 476         /**
 477          * @param string $path Storage path
 478          * @return bool Path container should have dir changes pushed to all backends
 479          */
 480         protected function replicateContainerDirChanges( $path ) {
 481                 list( , $shortCont, ) = self::splitStoragePath( $path );
 482                 return !in_array( $shortCont, $this->noPushDirConts );
 483         }
 484
 485         /**
 486          * @see FileBackend::doPrepare()
 487          * @return Status
 488          */
 489         protected function doPrepare( array $params ) {
 490                 $status = Status::newGood();
 491                 $replicate = $this->replicateContainerDirChanges( $params['dir'] );
 492                 foreach ( $this->backends as $index => $backend ) {
 493                         if ( $replicate || $index == $this->masterIndex ) {
 494                                 $realParams = $this->substOpPaths( $params, $backend );
 495                                 $status->merge( $backend->doPrepare( $realParams ) );
 496                         }
 497                 }
 498                 return $status;
 499         }
 500
 501         /**
 502          * @see FileBackend::doSecure()
 503          * @param array $params
 504          * @return Status
 505          */
 506         protected function doSecure( array $params ) {
 507                 $status = Status::newGood();
 508                 $replicate = $this->replicateContainerDirChanges( $params['dir'] );
 509                 foreach ( $this->backends as $index => $backend ) {
 510                         if ( $replicate || $index == $this->masterIndex ) {
 511                                 $realParams = $this->substOpPaths( $params, $backend );
 512                                 $status->merge( $backend->doSecure( $realParams ) );
 513                         }
 514                 }
 515                 return $status;
 516         }
 517
 518         /**
 519          * @see FileBackend::doPublish()
 520          * @param array $params
 521          * @return Status
 522          */
 523         protected function doPublish( array $params ) {
 524                 $status = Status::newGood();
 525                 $replicate = $this->replicateContainerDirChanges( $params['dir'] );
 526                 foreach ( $this->backends as $index => $backend ) {
 527                         if ( $replicate || $index == $this->masterIndex ) {
 528                                 $realParams = $this->substOpPaths( $params, $backend );
 529                                 $status->merge( $backend->doPublish( $realParams ) );
 530                         }
 531                 }
 532                 return $status;
 533         }
 534
 535         /**
 536          * @see FileBackend::doClean()
 537          * @param array $params
 538          * @return Status
 539          */
 540         protected function doClean( array $params ) {
 541                 $status = Status::newGood();
 542                 $replicate = $this->replicateContainerDirChanges( $params['dir'] );
 543                 foreach ( $this->backends as $index => $backend ) {
 544                         if ( $replicate || $index == $this->masterIndex ) {
 545                                 $realParams = $this->substOpPaths( $params, $backend );
 546                                 $status->merge( $backend->doClean( $realParams ) );
 547                         }
 548                 }
 549                 return $status;
 550         }
 551
 552         /**
 553          * @see FileBackend::concatenate()
 554          * @param array $params
 555          * @return Status
 556          */
 557         public function concatenate( array $params ) {
 558                 // We are writing to an FS file, so we don't need to do this per-backend
 559                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 560                 return $this->backends[$this->masterIndex]->concatenate( $realParams );
 561         }
 562
 563         /**
 564          * @see FileBackend::fileExists()
 565          * @param array $params
 566          * @return bool|null
 567          */
 568         public function fileExists( array $params ) {
 569                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 570                 return $this->backends[$this->masterIndex]->fileExists( $realParams );
 571         }
 572
 573         /**
 574          * @see FileBackend::getFileTimestamp()
 575          * @param array $params
 576          * @return bool|string
 577          */
 578         public function getFileTimestamp( array $params ) {
 579                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 580                 return $this->backends[$this->masterIndex]->getFileTimestamp( $realParams );
 581         }
 582
 583         /**
 584          * @see FileBackend::getFileSize()
 585          * @param array $params
 586          * @return bool|int
 587          */
 588         public function getFileSize( array $params ) {
 589                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 590                 return $this->backends[$this->masterIndex]->getFileSize( $realParams );
 591         }
 592
 593         /**
 594          * @see FileBackend::getFileStat()
 595          * @param array $params
 596          * @return Array|bool|null
 597          */
 598         public function getFileStat( array $params ) {
 599                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 600                 return $this->backends[$this->masterIndex]->getFileStat( $realParams );
 601         }
 602
 603         /**
 604          * @see FileBackend::getFileContentsMulti()
 605          * @param array $params
 606          * @return bool|string
 607          */
 608         public function getFileContentsMulti( array $params ) {
 609                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 610                 $contentsM = $this->backends[$this->masterIndex]->getFileContentsMulti( $realParams );
 611
 612                 $contents = array(); // (path => FSFile) mapping using the proxy backend's name
 613                 foreach ( $contentsM as $path => $data ) {
 614                         $contents[$this->unsubstPaths( $path )] = $data;
 615                 }
 616                 return $contents;
 617         }
 618
 619         /**
 620          * @see FileBackend::getFileSha1Base36()
 621          * @param array $params
 622          * @return bool|string
 623          */
 624         public function getFileSha1Base36( array $params ) {
 625                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 626                 return $this->backends[$this->masterIndex]->getFileSha1Base36( $realParams );
 627         }
 628
 629         /**
 630          * @see FileBackend::getFileProps()
 631          * @param array $params
 632          * @return Array
 633          */
 634         public function getFileProps( array $params ) {
 635                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 636                 return $this->backends[$this->masterIndex]->getFileProps( $realParams );
 637         }
 638
 639         /**
 640          * @see FileBackend::streamFile()
 641          * @param array $params
 642          * @return \Status
 643          */
 644         public function streamFile( array $params ) {
 645                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 646                 return $this->backends[$this->masterIndex]->streamFile( $realParams );
 647         }
 648
 649         /**
 650          * @see FileBackend::getLocalReferenceMulti()
 651          * @param array $params
 652          * @return FSFile|null
 653          */
 654         public function getLocalReferenceMulti( array $params ) {
 655                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 656                 $fsFilesM = $this->backends[$this->masterIndex]->getLocalReferenceMulti( $realParams );
 657
 658                 $fsFiles = array(); // (path => FSFile) mapping using the proxy backend's name
 659                 foreach ( $fsFilesM as $path => $fsFile ) {
 660                         $fsFiles[$this->unsubstPaths( $path )] = $fsFile;
 661                 }
 662                 return $fsFiles;
 663         }
 664
 665         /**
 666          * @see FileBackend::getLocalCopyMulti()
 667          * @param array $params
 668          * @return null|TempFSFile
 669          */
 670         public function getLocalCopyMulti( array $params ) {
 671                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 672                 $tempFilesM = $this->backends[$this->masterIndex]->getLocalCopyMulti( $realParams );
 673
 674                 $tempFiles = array(); // (path => TempFSFile) mapping using the proxy backend's name
 675                 foreach ( $tempFilesM as $path => $tempFile ) {
 676                         $tempFiles[$this->unsubstPaths( $path )] = $tempFile;
 677                 }
 678                 return $tempFiles;
 679         }
 680
 681         /**
 682          * @see FileBackend::getFileHttpUrl()
 683          * @return string|null
 684          */
 685         public function getFileHttpUrl( array $params ) {
 686                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 687                 return $this->backends[$this->masterIndex]->getFileHttpUrl( $realParams );
 688         }
 689
 690         /**
 691          * @see FileBackend::directoryExists()
 692          * @param array $params
 693          * @return bool|null
 694          */
 695         public function directoryExists( array $params ) {
 696                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 697                 return $this->backends[$this->masterIndex]->directoryExists( $realParams );
 698         }
 699
 700         /**
 701          * @see FileBackend::getSubdirectoryList()
 702          * @param array $params
 703          * @return Array|null|Traversable
 704          */
 705         public function getDirectoryList( array $params ) {
 706                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 707                 return $this->backends[$this->masterIndex]->getDirectoryList( $realParams );
 708         }
 709
 710         /**
 711          * @see FileBackend::getFileList()
 712          * @param array $params
 713          * @return Array|null|\Traversable
 714          */
 715         public function getFileList( array $params ) {
 716                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 717                 return $this->backends[$this->masterIndex]->getFileList( $realParams );
 718         }
 719
 720         /**
 721          * @see FileBackend::clearCache()
 722          */
 723         public function clearCache( array $paths = null ) {
 724                 foreach ( $this->backends as $backend ) {
 725                         $realPaths = is_array( $paths ) ? $this->substPaths( $paths, $backend ) : null;
 726                         $backend->clearCache( $realPaths );
 727                 }
 728         }
 729
 730         /**
 731          * @see FileBackend::getScopedLocksForOps()
 732          */
 733         public function getScopedLocksForOps( array $ops, Status $status ) {
 734                 $fileOps = $this->backends[$this->masterIndex]->getOperationsInternal( $ops );
 735                 // Get the paths to lock from the master backend
 736                 $paths = $this->backends[$this->masterIndex]->getPathsToLockForOpsInternal( $fileOps );
 737                 // Get the paths under the proxy backend's name
 738                 $paths['sh'] = $this->unsubstPaths( $paths['sh'] );
 739                 $paths['ex'] = $this->unsubstPaths( $paths['ex'] );
 740                 return array(
 741                         $this->getScopedFileLocks( $paths['sh'], LockManager::LOCK_UW, $status ),
 742                         $this->getScopedFileLocks( $paths['ex'], LockManager::LOCK_EX, $status )
 743                 );
 744         }
 745 }