includes/libs/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  */
  23
  24 /**
  25  * @brief Proxy backend that mirrors writes to several internal backends.
  26  *
  27  * This class defines a multi-write backend. Multiple backends can be
  28  * registered to this proxy backend and it will act as a single backend.
  29  * Use this when all access to those backends is through this proxy backend.
  30  * At least one of the backends must be declared the "master" backend.
  31  *
  32  * Only use this class when transitioning from one storage system to another.
  33  *
  34  * Read operations are only done on the 'master' backend for consistency.
  35  * Write operations are performed on all backends, starting with the master.
  36  * This makes a best-effort to have transactional semantics, but since requests
  37  * may sometimes fail, the use of "autoResync" or background scripts to fix
  38  * inconsistencies is important.
  39  *
  40  * @ingroup FileBackend
  41  * @since 1.19
  42  */
  43 class FileBackendMultiWrite extends FileBackend {
  44         /** @var FileBackendStore[] Prioritized list of FileBackendStore objects */
  45         protected $backends = [];
  46
  47         /** @var int Index of master backend */
  48         protected $masterIndex = -1;
  49         /** @var int Index of read affinity backend */
  50         protected $readIndex = -1;
  51
  52         /** @var int Bitfield */
  53         protected $syncChecks = 0;
  54         /** @var string|bool */
  55         protected $autoResync = false;
  56
  57         /** @var bool */
  58         protected $asyncWrites = false;
  59
  60         /* Possible internal backend consistency checks */
  61         const CHECK_SIZE = 1;
  62         const CHECK_TIME = 2;
  63         const CHECK_SHA1 = 4;
  64
  65         /**
  66          * Construct a proxy backend that consists of several internal backends.
  67          * Locking, journaling, and read-only checks are handled by the proxy backend.
  68          *
  69          * Additional $config params include:
  70          *   - backends       : Array of backend config and multi-backend settings.
  71          *                      Each value is the config used in the constructor of a
  72          *                      FileBackendStore class, but with these additional settings:
  73          *                        - class         : The name of the backend class
  74          *                        - isMultiMaster : This must be set for one backend.
  75          *                        - readAffinity  : Use this for reads without 'latest' set.
  76          *   - syncChecks     : Integer bitfield of internal backend sync checks to perform.
  77          *                      Possible bits include the FileBackendMultiWrite::CHECK_* constants.
  78          *                      There are constants for SIZE, TIME, and SHA1.
  79          *                      The checks are done before allowing any file operations.
  80          *   - autoResync     : Automatically resync the clone backends to the master backend
  81          *                      when pre-operation sync checks fail. This should only be used
  82          *                      if the master backend is stable and not missing any files.
  83          *                      Use "conservative" to limit resyncing to copying newer master
  84          *                      backend files over older (or non-existing) clone backend files.
  85          *                      Cases that cannot be handled will result in operation abortion.
  86          *   - replication    : Set to 'async' to defer file operations on the non-master backends.
  87          *                      This will apply such updates post-send for web requests. Note that
  88          *                      any checks from "syncChecks" are still synchronous.
  89          *
  90          * @param array $config
  91          * @throws FileBackendError
  92          */
  93         public function __construct( array $config ) {
  94                 parent::__construct( $config );
  95                 $this->syncChecks = $config['syncChecks'] ?? self::CHECK_SIZE;
  96                 $this->autoResync = $config['autoResync'] ?? false;
  97                 $this->asyncWrites = isset( $config['replication'] ) && $config['replication'] === 'async';
  98                 // Construct backends here rather than via registration
  99                 // to keep these backends hidden from outside the proxy.
 100                 $namesUsed = [];
 101                 foreach ( $config['backends'] as $index => $config ) {
 102                         $name = $config['name'];
 103                         if ( isset( $namesUsed[$name] ) ) { // don't break FileOp predicates
 104                                 throw new LogicException( "Two or more backends defined with the name $name." );
 105                         }
 106                         $namesUsed[$name] = 1;
 107                         // Alter certain sub-backend settings for sanity
 108                         unset( $config['readOnly'] ); // use proxy backend setting
 109                         unset( $config['fileJournal'] ); // use proxy backend journal
 110                         unset( $config['lockManager'] ); // lock under proxy backend
 111                         $config['domainId'] = $this->domainId; // use the proxy backend wiki ID
 112                         if ( !empty( $config['isMultiMaster'] ) ) {
 113                                 if ( $this->masterIndex >= 0 ) {
 114                                         throw new LogicException( 'More than one master backend defined.' );
 115                                 }
 116                                 $this->masterIndex = $index; // this is the "master"
 117                                 $config['fileJournal'] = $this->fileJournal; // log under proxy backend
 118                         }
 119                         if ( !empty( $config['readAffinity'] ) ) {
 120                                 $this->readIndex = $index; // prefer this for reads
 121                         }
 122                         // Create sub-backend object
 123                         if ( !isset( $config['class'] ) ) {
 124                                 throw new InvalidArgumentException( 'No class given for a backend config.' );
 125                         }
 126                         $class = $config['class'];
 127                         $this->backends[$index] = new $class( $config );
 128                 }
 129                 if ( $this->masterIndex < 0 ) { // need backends and must have a master
 130                         throw new LogicException( 'No master backend defined.' );
 131                 }
 132                 if ( $this->readIndex < 0 ) {
 133                         $this->readIndex = $this->masterIndex; // default
 134                 }
 135         }
 136
 137         final protected function doOperationsInternal( array $ops, array $opts ) {
 138                 $status = $this->newStatus();
 139
 140                 $mbe = $this->backends[$this->masterIndex]; // convenience
 141
 142                 // Try to lock those files for the scope of this function...
 143                 $scopeLock = null;
 144                 if ( empty( $opts['nonLocking'] ) ) {
 145                         // Try to lock those files for the scope of this function...
 146                         /** @noinspection PhpUnusedLocalVariableInspection */
 147                         $scopeLock = $this->getScopedLocksForOps( $ops, $status );
 148                         if ( !$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                 // Get the list of paths to read/write...
 156                 $relevantPaths = $this->fileStoragePathsForOps( $ops );
 157                 // Check if the paths are valid and accessible on all backends...
 158                 $status->merge( $this->accessibilityCheck( $relevantPaths ) );
 159                 if ( !$status->isOK() ) {
 160                         return $status; // abort
 161                 }
 162                 // Do a consistency check to see if the backends are consistent...
 163                 $syncStatus = $this->consistencyCheck( $relevantPaths );
 164                 if ( !$syncStatus->isOK() ) {
 165                         wfDebugLog( 'FileOperation', static::class .
 166                                 " failed sync check: " . FormatJson::encode( $relevantPaths ) );
 167                         // Try to resync the clone backends to the master on the spot...
 168                         if ( $this->autoResync === false
 169                                 || !$this->resyncFiles( $relevantPaths, $this->autoResync )->isOK()
 170                         ) {
 171                                 $status->merge( $syncStatus );
 172
 173                                 return $status; // abort
 174                         }
 175                 }
 176                 // Actually attempt the operation batch on the master backend...
 177                 $realOps = $this->substOpBatchPaths( $ops, $mbe );
 178                 $masterStatus = $mbe->doOperations( $realOps, $opts );
 179                 $status->merge( $masterStatus );
 180                 // Propagate the operations to the clone backends if there were no unexpected errors
 181                 // and if there were either no expected errors or if the 'force' option was used.
 182                 // However, if nothing succeeded at all, then don't replicate any of the operations.
 183                 // If $ops only had one operation, this might avoid backend sync inconsistencies.
 184                 if ( $masterStatus->isOK() && $masterStatus->successCount > 0 ) {
 185                         foreach ( $this->backends as $index => $backend ) {
 186                                 if ( $index === $this->masterIndex ) {
 187                                         continue; // done already
 188                                 }
 189
 190                                 $realOps = $this->substOpBatchPaths( $ops, $backend );
 191                                 if ( $this->asyncWrites && !$this->hasVolatileSources( $ops ) ) {
 192                                         // Bind $scopeLock to the callback to preserve locks
 193                                         DeferredUpdates::addCallableUpdate(
 194                                                 function () use ( $backend, $realOps, $opts, $scopeLock, $relevantPaths ) {
 195                                                         wfDebugLog( 'FileOperationReplication',
 196                                                                 "'{$backend->getName()}' async replication; paths: " .
 197                                                                 FormatJson::encode( $relevantPaths ) );
 198                                                         $backend->doOperations( $realOps, $opts );
 199                                                 }
 200                                         );
 201                                 } else {
 202                                         wfDebugLog( 'FileOperationReplication',
 203                                                 "'{$backend->getName()}' sync replication; paths: " .
 204                                                 FormatJson::encode( $relevantPaths ) );
 205                                         $status->merge( $backend->doOperations( $realOps, $opts ) );
 206                                 }
 207                         }
 208                 }
 209                 // Make 'success', 'successCount', and 'failCount' fields reflect
 210                 // the overall operation, rather than all the batches for each backend.
 211                 // Do this by only using success values from the master backend's batch.
 212                 $status->success = $masterStatus->success;
 213                 $status->successCount = $masterStatus->successCount;
 214                 $status->failCount = $masterStatus->failCount;
 215
 216                 return $status;
 217         }
 218
 219         /**
 220          * Check that a set of files are consistent across all internal backends
 221          *
 222          * @param array $paths List of storage paths
 223          * @return StatusValue
 224          */
 225         public function consistencyCheck( array $paths ) {
 226                 $status = $this->newStatus();
 227                 if ( $this->syncChecks == 0 || count( $this->backends ) <= 1 ) {
 228                         return $status; // skip checks
 229                 }
 230
 231                 // Preload all of the stat info in as few round trips as possible...
 232                 foreach ( $this->backends as $backend ) {
 233                         $realPaths = $this->substPaths( $paths, $backend );
 234                         $backend->preloadFileStat( [ 'srcs' => $realPaths, 'latest' => true ] );
 235                 }
 236
 237                 $mBackend = $this->backends[$this->masterIndex];
 238                 foreach ( $paths as $path ) {
 239                         $params = [ 'src' => $path, 'latest' => true ];
 240                         $mParams = $this->substOpPaths( $params, $mBackend );
 241                         // Stat the file on the 'master' backend
 242                         $mStat = $mBackend->getFileStat( $mParams );
 243                         if ( $this->syncChecks & self::CHECK_SHA1 ) {
 244                                 $mSha1 = $mBackend->getFileSha1Base36( $mParams );
 245                         } else {
 246                                 $mSha1 = false;
 247                         }
 248                         // Check if all clone backends agree with the master...
 249                         foreach ( $this->backends as $index => $cBackend ) {
 250                                 if ( $index === $this->masterIndex ) {
 251                                         continue; // master
 252                                 }
 253                                 $cParams = $this->substOpPaths( $params, $cBackend );
 254                                 $cStat = $cBackend->getFileStat( $cParams );
 255                                 if ( $mStat ) { // file is in master
 256                                         if ( !$cStat ) { // file should exist
 257                                                 $status->fatal( 'backend-fail-synced', $path );
 258                                                 continue;
 259                                         }
 260                                         if ( $this->syncChecks & self::CHECK_SIZE ) {
 261                                                 if ( $cStat['size'] != $mStat['size'] ) { // wrong size
 262                                                         $status->fatal( 'backend-fail-synced', $path );
 263                                                         continue;
 264                                                 }
 265                                         }
 266                                         if ( $this->syncChecks & self::CHECK_TIME ) {
 267                                                 $mTs = wfTimestamp( TS_UNIX, $mStat['mtime'] );
 268                                                 $cTs = wfTimestamp( TS_UNIX, $cStat['mtime'] );
 269                                                 if ( abs( $mTs - $cTs ) > 30 ) { // outdated file somewhere
 270                                                         $status->fatal( 'backend-fail-synced', $path );
 271                                                         continue;
 272                                                 }
 273                                         }
 274                                         if ( $this->syncChecks & self::CHECK_SHA1 ) {
 275                                                 if ( $cBackend->getFileSha1Base36( $cParams ) !== $mSha1 ) { // wrong SHA1
 276                                                         $status->fatal( 'backend-fail-synced', $path );
 277                                                         continue;
 278                                                 }
 279                                         }
 280                                 } else { // file is not in master
 281                                         if ( $cStat ) { // file should not exist
 282                                                 $status->fatal( 'backend-fail-synced', $path );
 283                                         }
 284                                 }
 285                         }
 286                 }
 287
 288                 return $status;
 289         }
 290
 291         /**
 292          * Check that a set of file paths are usable across all internal backends
 293          *
 294          * @param array $paths List of storage paths
 295          * @return StatusValue
 296          */
 297         public function accessibilityCheck( array $paths ) {
 298                 $status = $this->newStatus();
 299                 if ( count( $this->backends ) <= 1 ) {
 300                         return $status; // skip checks
 301                 }
 302
 303                 foreach ( $paths as $path ) {
 304                         foreach ( $this->backends as $backend ) {
 305                                 $realPath = $this->substPaths( $path, $backend );
 306                                 if ( !$backend->isPathUsableInternal( $realPath ) ) {
 307                                         $status->fatal( 'backend-fail-usable', $path );
 308                                 }
 309                         }
 310                 }
 311
 312                 return $status;
 313         }
 314
 315         /**
 316          * Check that a set of files are consistent across all internal backends
 317          * and re-synchronize those files against the "multi master" if needed.
 318          *
 319          * @param array $paths List of storage paths
 320          * @param string|bool $resyncMode False, True, or "conservative"; see __construct()
 321          * @return StatusValue
 322          */
 323         public function resyncFiles( array $paths, $resyncMode = true ) {
 324                 $status = $this->newStatus();
 325
 326                 $mBackend = $this->backends[$this->masterIndex];
 327                 foreach ( $paths as $path ) {
 328                         $mPath = $this->substPaths( $path, $mBackend );
 329                         $mSha1 = $mBackend->getFileSha1Base36( [ 'src' => $mPath, 'latest' => true ] );
 330                         $mStat = $mBackend->getFileStat( [ 'src' => $mPath, 'latest' => true ] );
 331                         if ( $mStat === null || ( $mSha1 !== false && !$mStat ) ) { // sanity
 332                                 $status->fatal( 'backend-fail-internal', $this->name );
 333                                 wfDebugLog( 'FileOperation', __METHOD__
 334                                         . ': File is not available on the master backend' );
 335                                 continue; // file is not available on the master backend...
 336                         }
 337                         // Check of all clone backends agree with the master...
 338                         foreach ( $this->backends as $index => $cBackend ) {
 339                                 if ( $index === $this->masterIndex ) {
 340                                         continue; // master
 341                                 }
 342                                 $cPath = $this->substPaths( $path, $cBackend );
 343                                 $cSha1 = $cBackend->getFileSha1Base36( [ 'src' => $cPath, 'latest' => true ] );
 344                                 $cStat = $cBackend->getFileStat( [ 'src' => $cPath, 'latest' => true ] );
 345                                 if ( $cStat === null || ( $cSha1 !== false && !$cStat ) ) { // sanity
 346                                         $status->fatal( 'backend-fail-internal', $cBackend->getName() );
 347                                         wfDebugLog( 'FileOperation', __METHOD__ .
 348                                                 ': File is not available on the clone backend' );
 349                                         continue; // file is not available on the clone backend...
 350                                 }
 351                                 if ( $mSha1 === $cSha1 ) {
 352                                         // already synced; nothing to do
 353                                 } elseif ( $mSha1 !== false ) { // file is in master
 354                                         if ( $resyncMode === 'conservative'
 355                                                 && $cStat && $cStat['mtime'] > $mStat['mtime']
 356                                         ) {
 357                                                 $status->fatal( 'backend-fail-synced', $path );
 358                                                 continue; // don't rollback data
 359                                         }
 360                                         $fsFile = $mBackend->getLocalReference(
 361                                                 [ 'src' => $mPath, 'latest' => true ] );
 362                                         $status->merge( $cBackend->quickStore(
 363                                                 [ 'src' => $fsFile->getPath(), 'dst' => $cPath ]
 364                                         ) );
 365                                 } elseif ( $mStat === false ) { // file is not in master
 366                                         if ( $resyncMode === 'conservative' ) {
 367                                                 $status->fatal( 'backend-fail-synced', $path );
 368                                                 continue; // don't delete data
 369                                         }
 370                                         $status->merge( $cBackend->quickDelete( [ 'src' => $cPath ] ) );
 371                                 }
 372                         }
 373                 }
 374
 375                 if ( !$status->isOK() ) {
 376                         wfDebugLog( 'FileOperation', static::class .
 377                                 " failed to resync: " . FormatJson::encode( $paths ) );
 378                 }
 379
 380                 return $status;
 381         }
 382
 383         /**
 384          * Get a list of file storage paths to read or write for a list of operations
 385          *
 386          * @param array $ops Same format as doOperations()
 387          * @return array List of storage paths to files (does not include directories)
 388          */
 389         protected function fileStoragePathsForOps( array $ops ) {
 390                 $paths = [];
 391                 foreach ( $ops as $op ) {
 392                         if ( isset( $op['src'] ) ) {
 393                                 // For things like copy/move/delete with "ignoreMissingSource" and there
 394                                 // is no source file, nothing should happen and there should be no errors.
 395                                 if ( empty( $op['ignoreMissingSource'] )
 396                                         || $this->fileExists( [ 'src' => $op['src'] ] )
 397                                 ) {
 398                                         $paths[] = $op['src'];
 399                                 }
 400                         }
 401                         if ( isset( $op['srcs'] ) ) {
 402                                 $paths = array_merge( $paths, $op['srcs'] );
 403                         }
 404                         if ( isset( $op['dst'] ) ) {
 405                                 $paths[] = $op['dst'];
 406                         }
 407                 }
 408
 409                 return array_values( array_unique( array_filter( $paths, 'FileBackend::isStoragePath' ) ) );
 410         }
 411
 412         /**
 413          * Substitute the backend name in storage path parameters
 414          * for a set of operations with that of a given internal backend.
 415          *
 416          * @param array $ops List of file operation arrays
 417          * @param FileBackendStore $backend
 418          * @return array
 419          */
 420         protected function substOpBatchPaths( array $ops, FileBackendStore $backend ) {
 421                 $newOps = []; // operations
 422                 foreach ( $ops as $op ) {
 423                         $newOp = $op; // operation
 424                         foreach ( [ 'src', 'srcs', 'dst', 'dir' ] as $par ) {
 425                                 if ( isset( $newOp[$par] ) ) { // string or array
 426                                         $newOp[$par] = $this->substPaths( $newOp[$par], $backend );
 427                                 }
 428                         }
 429                         $newOps[] = $newOp;
 430                 }
 431
 432                 return $newOps;
 433         }
 434
 435         /**
 436          * Same as substOpBatchPaths() but for a single operation
 437          *
 438          * @param array $ops File operation array
 439          * @param FileBackendStore $backend
 440          * @return array
 441          */
 442         protected function substOpPaths( array $ops, FileBackendStore $backend ) {
 443                 $newOps = $this->substOpBatchPaths( [ $ops ], $backend );
 444
 445                 return $newOps[0];
 446         }
 447
 448         /**
 449          * Substitute the backend of storage paths with an internal backend's name
 450          *
 451          * @param array|string $paths List of paths or single string path
 452          * @param FileBackendStore $backend
 453          * @return array|string
 454          */
 455         protected function substPaths( $paths, FileBackendStore $backend ) {
 456                 return preg_replace(
 457                         '!^mwstore://' . preg_quote( $this->name, '!' ) . '/!',
 458                         StringUtils::escapeRegexReplacement( "mwstore://{$backend->getName()}/" ),
 459                         $paths // string or array
 460                 );
 461         }
 462
 463         /**
 464          * Substitute the backend of internal storage paths with the proxy backend's name
 465          *
 466          * @param array|string $paths List of paths or single string path
 467          * @return array|string
 468          */
 469         protected function unsubstPaths( $paths ) {
 470                 return preg_replace(
 471                         '!^mwstore://([^/]+)!',
 472                         StringUtils::escapeRegexReplacement( "mwstore://{$this->name}" ),
 473                         $paths // string or array
 474                 );
 475         }
 476
 477         /**
 478          * @param array $ops File operations for FileBackend::doOperations()
 479          * @return bool Whether there are file path sources with outside lifetime/ownership
 480          */
 481         protected function hasVolatileSources( array $ops ) {
 482                 foreach ( $ops as $op ) {
 483                         if ( $op['op'] === 'store' && !isset( $op['srcRef'] ) ) {
 484                                 return true; // source file might be deleted anytime after do*Operations()
 485                         }
 486                 }
 487
 488                 return false;
 489         }
 490
 491         protected function doQuickOperationsInternal( array $ops ) {
 492                 $status = $this->newStatus();
 493                 // Do the operations on the master backend; setting StatusValue fields...
 494                 $realOps = $this->substOpBatchPaths( $ops, $this->backends[$this->masterIndex] );
 495                 $masterStatus = $this->backends[$this->masterIndex]->doQuickOperations( $realOps );
 496                 $status->merge( $masterStatus );
 497                 // Propagate the operations to the clone backends...
 498                 foreach ( $this->backends as $index => $backend ) {
 499                         if ( $index === $this->masterIndex ) {
 500                                 continue; // done already
 501                         }
 502
 503                         $realOps = $this->substOpBatchPaths( $ops, $backend );
 504                         if ( $this->asyncWrites && !$this->hasVolatileSources( $ops ) ) {
 505                                 DeferredUpdates::addCallableUpdate(
 506                                         function () use ( $backend, $realOps ) {
 507                                                 $backend->doQuickOperations( $realOps );
 508                                         }
 509                                 );
 510                         } else {
 511                                 $status->merge( $backend->doQuickOperations( $realOps ) );
 512                         }
 513                 }
 514                 // Make 'success', 'successCount', and 'failCount' fields reflect
 515                 // the overall operation, rather than all the batches for each backend.
 516                 // Do this by only using success values from the master backend's batch.
 517                 $status->success = $masterStatus->success;
 518                 $status->successCount = $masterStatus->successCount;
 519                 $status->failCount = $masterStatus->failCount;
 520
 521                 return $status;
 522         }
 523
 524         protected function doPrepare( array $params ) {
 525                 return $this->doDirectoryOp( 'prepare', $params );
 526         }
 527
 528         protected function doSecure( array $params ) {
 529                 return $this->doDirectoryOp( 'secure', $params );
 530         }
 531
 532         protected function doPublish( array $params ) {
 533                 return $this->doDirectoryOp( 'publish', $params );
 534         }
 535
 536         protected function doClean( array $params ) {
 537                 return $this->doDirectoryOp( 'clean', $params );
 538         }
 539
 540         /**
 541          * @param string $method One of (doPrepare,doSecure,doPublish,doClean)
 542          * @param array $params Method arguments
 543          * @return StatusValue
 544          */
 545         protected function doDirectoryOp( $method, array $params ) {
 546                 $status = $this->newStatus();
 547
 548                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 549                 $masterStatus = $this->backends[$this->masterIndex]->$method( $realParams );
 550                 $status->merge( $masterStatus );
 551
 552                 foreach ( $this->backends as $index => $backend ) {
 553                         if ( $index === $this->masterIndex ) {
 554                                 continue; // already done
 555                         }
 556
 557                         $realParams = $this->substOpPaths( $params, $backend );
 558                         if ( $this->asyncWrites ) {
 559                                 DeferredUpdates::addCallableUpdate(
 560                                         function () use ( $backend, $method, $realParams ) {
 561                                                 $backend->$method( $realParams );
 562                                         }
 563                                 );
 564                         } else {
 565                                 $status->merge( $backend->$method( $realParams ) );
 566                         }
 567                 }
 568
 569                 return $status;
 570         }
 571
 572         public function concatenate( array $params ) {
 573                 $status = $this->newStatus();
 574                 // We are writing to an FS file, so we don't need to do this per-backend
 575                 $index = $this->getReadIndexFromParams( $params );
 576                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 577
 578                 $status->merge( $this->backends[$index]->concatenate( $realParams ) );
 579
 580                 return $status;
 581         }
 582
 583         public function fileExists( array $params ) {
 584                 $index = $this->getReadIndexFromParams( $params );
 585                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 586
 587                 return $this->backends[$index]->fileExists( $realParams );
 588         }
 589
 590         public function getFileTimestamp( array $params ) {
 591                 $index = $this->getReadIndexFromParams( $params );
 592                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 593
 594                 return $this->backends[$index]->getFileTimestamp( $realParams );
 595         }
 596
 597         public function getFileSize( array $params ) {
 598                 $index = $this->getReadIndexFromParams( $params );
 599                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 600
 601                 return $this->backends[$index]->getFileSize( $realParams );
 602         }
 603
 604         public function getFileStat( array $params ) {
 605                 $index = $this->getReadIndexFromParams( $params );
 606                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 607
 608                 return $this->backends[$index]->getFileStat( $realParams );
 609         }
 610
 611         public function getFileXAttributes( array $params ) {
 612                 $index = $this->getReadIndexFromParams( $params );
 613                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 614
 615                 return $this->backends[$index]->getFileXAttributes( $realParams );
 616         }
 617
 618         public function getFileContentsMulti( array $params ) {
 619                 $index = $this->getReadIndexFromParams( $params );
 620                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 621
 622                 $contentsM = $this->backends[$index]->getFileContentsMulti( $realParams );
 623
 624                 $contents = []; // (path => FSFile) mapping using the proxy backend's name
 625                 foreach ( $contentsM as $path => $data ) {
 626                         $contents[$this->unsubstPaths( $path )] = $data;
 627                 }
 628
 629                 return $contents;
 630         }
 631
 632         public function getFileSha1Base36( array $params ) {
 633                 $index = $this->getReadIndexFromParams( $params );
 634                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 635
 636                 return $this->backends[$index]->getFileSha1Base36( $realParams );
 637         }
 638
 639         public function getFileProps( array $params ) {
 640                 $index = $this->getReadIndexFromParams( $params );
 641                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 642
 643                 return $this->backends[$index]->getFileProps( $realParams );
 644         }
 645
 646         public function streamFile( array $params ) {
 647                 $index = $this->getReadIndexFromParams( $params );
 648                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 649
 650                 return $this->backends[$index]->streamFile( $realParams );
 651         }
 652
 653         public function getLocalReferenceMulti( array $params ) {
 654                 $index = $this->getReadIndexFromParams( $params );
 655                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 656
 657                 $fsFilesM = $this->backends[$index]->getLocalReferenceMulti( $realParams );
 658
 659                 $fsFiles = []; // (path => FSFile) mapping using the proxy backend's name
 660                 foreach ( $fsFilesM as $path => $fsFile ) {
 661                         $fsFiles[$this->unsubstPaths( $path )] = $fsFile;
 662                 }
 663
 664                 return $fsFiles;
 665         }
 666
 667         public function getLocalCopyMulti( array $params ) {
 668                 $index = $this->getReadIndexFromParams( $params );
 669                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 670
 671                 $tempFilesM = $this->backends[$index]->getLocalCopyMulti( $realParams );
 672
 673                 $tempFiles = []; // (path => TempFSFile) mapping using the proxy backend's name
 674                 foreach ( $tempFilesM as $path => $tempFile ) {
 675                         $tempFiles[$this->unsubstPaths( $path )] = $tempFile;
 676                 }
 677
 678                 return $tempFiles;
 679         }
 680
 681         public function getFileHttpUrl( array $params ) {
 682                 $index = $this->getReadIndexFromParams( $params );
 683                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 684
 685                 return $this->backends[$index]->getFileHttpUrl( $realParams );
 686         }
 687
 688         public function directoryExists( array $params ) {
 689                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 690
 691                 return $this->backends[$this->masterIndex]->directoryExists( $realParams );
 692         }
 693
 694         public function getDirectoryList( array $params ) {
 695                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 696
 697                 return $this->backends[$this->masterIndex]->getDirectoryList( $realParams );
 698         }
 699
 700         public function getFileList( array $params ) {
 701                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 702
 703                 return $this->backends[$this->masterIndex]->getFileList( $realParams );
 704         }
 705
 706         public function getFeatures() {
 707                 return $this->backends[$this->masterIndex]->getFeatures();
 708         }
 709
 710         public function clearCache( array $paths = null ) {
 711                 foreach ( $this->backends as $backend ) {
 712                         $realPaths = is_array( $paths ) ? $this->substPaths( $paths, $backend ) : null;
 713                         $backend->clearCache( $realPaths );
 714                 }
 715         }
 716
 717         public function preloadCache( array $paths ) {
 718                 $realPaths = $this->substPaths( $paths, $this->backends[$this->readIndex] );
 719                 $this->backends[$this->readIndex]->preloadCache( $realPaths );
 720         }
 721
 722         public function preloadFileStat( array $params ) {
 723                 $index = $this->getReadIndexFromParams( $params );
 724                 $realParams = $this->substOpPaths( $params, $this->backends[$index] );
 725
 726                 return $this->backends[$index]->preloadFileStat( $realParams );
 727         }
 728
 729         public function getScopedLocksForOps( array $ops, StatusValue $status ) {
 730                 $realOps = $this->substOpBatchPaths( $ops, $this->backends[$this->masterIndex] );
 731                 $fileOps = $this->backends[$this->masterIndex]->getOperationsInternal( $realOps );
 732                 // Get the paths to lock from the master backend
 733                 $paths = $this->backends[$this->masterIndex]->getPathsToLockForOpsInternal( $fileOps );
 734                 // Get the paths under the proxy backend's name
 735                 $pbPaths = [
 736                         LockManager::LOCK_UW => $this->unsubstPaths( $paths[LockManager::LOCK_UW] ),
 737                         LockManager::LOCK_EX => $this->unsubstPaths( $paths[LockManager::LOCK_EX] )
 738                 ];
 739
 740                 // Actually acquire the locks
 741                 return $this->getScopedFileLocks( $pbPaths, 'mixed', $status );
 742         }
 743
 744         /**
 745          * @param array $params
 746          * @return int The master or read affinity backend index, based on $params['latest']
 747          */
 748         protected function getReadIndexFromParams( array $params ) {
 749                 return !empty( $params['latest'] ) ? $this->masterIndex : $this->readIndex;
 750         }
 751 }