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