includes/filerepo/backend/FileBackendMultiWrite.php

   1 <?php
   2 /**
   3  * @file
   4  * @ingroup FileBackend
   5  * @author Aaron Schulz
   6  */
   7
   8 /**
   9  * This class defines a multi-write backend. Multiple backends can be
  10  * registered to this proxy backend and it will act as a single backend.
  11  * Use this when all access to those backends is through this proxy backend.
  12  * At least one of the backends must be declared the "master" backend.
  13  *
  14  * Only use this class when transitioning from one storage system to another.
  15  *
  16  * Read operations are only done on the 'master' backend for consistency.
  17  * Write operations are performed on all backends, in the order defined.
  18  * If an operation fails on one backend it will be rolled back from the others.
  19  *
  20  * @ingroup FileBackend
  21  * @since 1.19
  22  */
  23 class FileBackendMultiWrite extends FileBackendBase {
  24         /** @var Array Prioritized list of FileBackend objects */
  25         protected $backends = array(); // array of (backend index => backends)
  26         protected $masterIndex = -1; // index of master backend
  27
  28         /**
  29          * Construct a proxy backend that consists of several internal backends.
  30          * Additional $config params include:
  31          *     'backends'    : Array of backend config and multi-backend settings.
  32          *                     Each value is the config used in the constructor of a
  33          *                     FileBackend class, but with these additional settings:
  34          *                         'class'         : The name of the backend class
  35          *                         'isMultiMaster' : This must be set for one backend.
  36          * @param $config Array
  37          */
  38         public function __construct( array $config ) {
  39                 parent::__construct( $config );
  40                 $namesUsed = array();
  41                 // Construct backends here rather than via registration
  42                 // to keep these backends hidden from outside the proxy.
  43                 foreach ( $config['backends'] as $index => $config ) {
  44                         $name = $config['name'];
  45                         if ( isset( $namesUsed[$name] ) ) { // don't break FileOp predicates
  46                                 throw new MWException( "Two or more backends defined with the name $name." );
  47                         }
  48                         $namesUsed[$name] = 1;
  49                         if ( !isset( $config['class'] ) ) {
  50                                 throw new MWException( 'No class given for a backend config.' );
  51                         }
  52                         $class = $config['class'];
  53                         $this->backends[$index] = new $class( $config );
  54                         if ( !empty( $config['isMultiMaster'] ) ) {
  55                                 if ( $this->masterIndex >= 0 ) {
  56                                         throw new MWException( 'More than one master backend defined.' );
  57                                 }
  58                                 $this->masterIndex = $index;
  59                         }
  60                 }
  61                 if ( $this->masterIndex < 0 ) { // need backends and must have a master
  62                         throw new MWException( 'No master backend defined.' );
  63                 }
  64         }
  65
  66         /**
  67          * @see FileBackendBase::doOperationsInternal()
  68          */
  69         final protected function doOperationsInternal( array $ops, array $opts ) {
  70                 $status = Status::newGood();
  71
  72                 $performOps = array(); // list of FileOp objects
  73                 $filesRead = $filesChanged = array(); // storage paths used
  74                 // Build up a list of FileOps. The list will have all the ops
  75                 // for one backend, then all the ops for the next, and so on.
  76                 // These batches of ops are all part of a continuous array.
  77                 // Also build up a list of files read/changed...
  78                 foreach ( $this->backends as $index => $backend ) {
  79                         $backendOps = $this->substOpBatchPaths( $ops, $backend );
  80                         // Add on the operation batch for this backend
  81                         $performOps = array_merge( $performOps, $backend->getOperations( $backendOps ) );
  82                         if ( $index == 0 ) { // first batch
  83                                 // Get the files used for these operations. Each backend has a batch of
  84                                 // the same operations, so we only need to get them from the first batch.
  85                                 foreach ( $performOps as $fileOp ) {
  86                                         $filesRead = array_merge( $filesRead, $fileOp->storagePathsRead() );
  87                                         $filesChanged = array_merge( $filesChanged, $fileOp->storagePathsChanged() );
  88                                 }
  89                                 // Get the paths under the proxy backend's name
  90                                 $filesRead = $this->unsubstPaths( $filesRead );
  91                                 $filesChanged = $this->unsubstPaths( $filesChanged );
  92                         }
  93                 }
  94
  95                 // Try to lock those files for the scope of this function...
  96                 if ( empty( $opts['nonLocking'] ) ) {
  97                         $filesLockSh = array_diff( $filesRead, $filesChanged ); // optimization
  98                         $filesLockEx = $filesChanged;
  99                         $scopeLockS = $this->getScopedFileLocks( $filesLockSh, LockManager::LOCK_UW, $status );
 100                         $scopeLockE = $this->getScopedFileLocks( $filesLockEx, LockManager::LOCK_EX, $status );
 101                         if ( !$status->isOK() ) {
 102                                 return $status; // abort
 103                         }
 104                 }
 105
 106                 // Clear any cache entries (after locks acquired)
 107                 $this->clearCache();
 108
 109                 // Do a consistency check to see if the backends agree
 110                 if ( count( $this->backends ) > 1 ) {
 111                         $status->merge( $this->consistencyCheck( array_merge( $filesRead, $filesChanged ) ) );
 112                         if ( !$status->isOK() ) {
 113                                 return $status; // abort
 114                         }
 115                 }
 116
 117                 // Actually attempt the operation batch...
 118                 $subStatus = FileOp::attemptBatch( $performOps, $opts );
 119
 120                 $success = array();
 121                 $failCount = $successCount = 0;
 122                 // Make 'success', 'successCount', and 'failCount' fields reflect
 123                 // the overall operation, rather than all the batches for each backend.
 124                 // Do this by only using success values from the master backend's batch.
 125                 $batchStart = $this->masterIndex * count( $ops );
 126                 $batchEnd = $batchStart + count( $ops ) - 1;
 127                 for ( $i = $batchStart; $i <= $batchEnd; $i++ ) {
 128                         if ( !isset( $subStatus->success[$i] ) ) {
 129                                 break; // failed out before trying this op
 130                         } elseif ( $subStatus->success[$i] ) {
 131                                 ++$successCount;
 132                         } else {
 133                                 ++$failCount;
 134                         }
 135                         $success[] = $subStatus->success[$i];
 136                 }
 137                 $subStatus->success = $success;
 138                 $subStatus->successCount = $successCount;
 139                 $subStatus->failCount = $failCount;
 140
 141                 // Merge errors into status fields
 142                 $status->merge( $subStatus );
 143                 $status->success = $subStatus->success; // not done in merge()
 144
 145                 return $status;
 146         }
 147
 148         /**
 149          * Check that a set of files are consistent across all internal backends
 150          *
 151          * @param $paths Array
 152          * @return Status
 153          */
 154         public function consistencyCheck( array $paths ) {
 155                 $status = Status::newGood();
 156
 157                 $mBackend = $this->backends[$this->masterIndex];
 158                 foreach ( array_unique( $paths ) as $path ) {
 159                         $params = array( 'src' => $path );
 160                         // Stat the file on the 'master' backend
 161                         $mStat = $mBackend->getFileStat( $this->substOpPaths( $params, $mBackend ) );
 162                         // Check of all clone backends agree with the master...
 163                         foreach ( $this->backends as $index => $cBackend ) {
 164                                 if ( $index === $this->masterIndex ) {
 165                                         continue; // master
 166                                 }
 167                                 $cStat = $cBackend->getFileStat( $this->substOpPaths( $params, $cBackend ) );
 168                                 if ( $mStat ) { // file is in master
 169                                         if ( !$cStat ) { // file should exist
 170                                                 $status->fatal( 'backend-fail-synced', $path );
 171                                         } elseif ( $cStat['size'] != $mStat['size'] ) { // wrong size
 172                                                 $status->fatal( 'backend-fail-synced', $path );
 173                                         } else {
 174                                                 $mTs = wfTimestamp( TS_UNIX, $mStat['mtime'] );
 175                                                 $cTs = wfTimestamp( TS_UNIX, $cStat['mtime'] );
 176                                                 if ( abs( $mTs - $cTs ) > 30 ) { // outdated file somewhere
 177                                                         $status->fatal( 'backend-fail-synced', $path );
 178                                                 }
 179                                         }
 180                                 } else { // file is not in master
 181                                         if ( $cStat ) { // file should not exist
 182                                                 $status->fatal( 'backend-fail-synced', $path );
 183                                         }
 184                                 }
 185                         }
 186                 }
 187
 188                 return $status;
 189         }
 190
 191         /**
 192          * Substitute the backend name in storage path parameters
 193          * for a set of operations with that of a given internal backend.
 194          *
 195          * @param $ops Array List of file operation arrays
 196          * @param $backend FileBackend
 197          * @return Array
 198          */
 199         protected function substOpBatchPaths( array $ops, FileBackend $backend ) {
 200                 $newOps = array(); // operations
 201                 foreach ( $ops as $op ) {
 202                         $newOp = $op; // operation
 203                         foreach ( array( 'src', 'srcs', 'dst', 'dir' ) as $par ) {
 204                                 if ( isset( $newOp[$par] ) ) { // string or array
 205                                         $newOp[$par] = $this->substPaths( $newOp[$par], $backend );
 206                                 }
 207                         }
 208                         $newOps[] = $newOp;
 209                 }
 210                 return $newOps;
 211         }
 212
 213         /**
 214          * Same as substOpBatchPaths() but for a single operation
 215          *
 216          * @param $op File operation array
 217          * @param $backend FileBackend
 218          * @return Array
 219          */
 220         protected function substOpPaths( array $ops, FileBackend $backend ) {
 221                 $newOps = $this->substOpBatchPaths( array( $ops ), $backend );
 222                 return $newOps[0];
 223         }
 224
 225         /**
 226          * Substitute the backend of storage paths with an internal backend's name
 227          *
 228          * @param $paths Array|string List of paths or single string path
 229          * @param $backend FileBackend
 230          * @return Array|string
 231          */
 232         protected function substPaths( $paths, FileBackend $backend ) {
 233                 return preg_replace(
 234                         '!^mwstore://' . preg_quote( $this->name ) . '/!',
 235                         'mwstore://' . $backend->getName() . '/',
 236                         $paths // string or array
 237                 );
 238         }
 239
 240         /**
 241          * Substitute the backend of internal storage paths with the proxy backend's name
 242          *
 243          * @param $paths Array|string List of paths or single string path
 244          * @return Array|string
 245          */
 246         protected function unsubstPaths( $paths ) {
 247                 return preg_replace(
 248                         '!^mwstore://([^/]+)!',
 249                         "mwstore://{$this->name}",
 250                         $paths // string or array
 251                 );
 252         }
 253
 254         /**
 255          * @see FileBackendBase::doPrepare()
 256          */
 257         public function doPrepare( array $params ) {
 258                 $status = Status::newGood();
 259                 foreach ( $this->backends as $backend ) {
 260                         $realParams = $this->substOpPaths( $params, $backend );
 261                         $status->merge( $backend->doPrepare( $realParams ) );
 262                 }
 263                 return $status;
 264         }
 265
 266         /**
 267          * @see FileBackendBase::doSecure()
 268          */
 269         public function doSecure( array $params ) {
 270                 $status = Status::newGood();
 271                 foreach ( $this->backends as $backend ) {
 272                         $realParams = $this->substOpPaths( $params, $backend );
 273                         $status->merge( $backend->doSecure( $realParams ) );
 274                 }
 275                 return $status;
 276         }
 277
 278         /**
 279          * @see FileBackendBase::doClean()
 280          */
 281         public function doClean( array $params ) {
 282                 $status = Status::newGood();
 283                 foreach ( $this->backends as $backend ) {
 284                         $realParams = $this->substOpPaths( $params, $backend );
 285                         $status->merge( $backend->doClean( $realParams ) );
 286                 }
 287                 return $status;
 288         }
 289
 290         /**
 291          * @see FileBackendBase::getFileList()
 292          */
 293         public function concatenate( array $params ) {
 294                 // We are writing to an FS file, so we don't need to do this per-backend
 295                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 296                 return $this->backends[$this->masterIndex]->concatenate( $realParams );
 297         }
 298
 299         /**
 300          * @see FileBackendBase::fileExists()
 301          */
 302         public function fileExists( array $params ) {
 303                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 304                 return $this->backends[$this->masterIndex]->fileExists( $realParams );
 305         }
 306
 307         /**
 308          * @see FileBackendBase::getFileTimestamp()
 309          */
 310         public function getFileTimestamp( array $params ) {
 311                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 312                 return $this->backends[$this->masterIndex]->getFileTimestamp( $realParams );
 313         }
 314
 315         /**
 316          * @see FileBackendBase::getFileSize()
 317          */
 318         public function getFileSize( array $params ) {
 319                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 320                 return $this->backends[$this->masterIndex]->getFileSize( $realParams );
 321         }
 322
 323         /**
 324          * @see FileBackendBase::getFileStat()
 325          */
 326         public function getFileStat( array $params ) {
 327                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 328                 return $this->backends[$this->masterIndex]->getFileStat( $realParams );
 329         }
 330
 331         /**
 332          * @see FileBackendBase::getFileContents()
 333          */
 334         public function getFileContents( array $params ) {
 335                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 336                 return $this->backends[$this->masterIndex]->getFileContents( $realParams );
 337         }
 338
 339         /**
 340          * @see FileBackendBase::getFileSha1Base36()
 341          */
 342         public function getFileSha1Base36( array $params ) {
 343                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 344                 return $this->backends[$this->masterIndex]->getFileSha1Base36( $realParams );
 345         }
 346
 347         /**
 348          * @see FileBackendBase::getFileProps()
 349          */
 350         public function getFileProps( array $params ) {
 351                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 352                 return $this->backends[$this->masterIndex]->getFileProps( $realParams );
 353         }
 354
 355         /**
 356          * @see FileBackendBase::streamFile()
 357          */
 358         public function streamFile( array $params ) {
 359                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 360                 return $this->backends[$this->masterIndex]->streamFile( $realParams );
 361         }
 362
 363         /**
 364          * @see FileBackendBase::getLocalReference()
 365          */
 366         public function getLocalReference( array $params ) {
 367                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 368                 return $this->backends[$this->masterIndex]->getLocalReference( $realParams );
 369         }
 370
 371         /**
 372          * @see FileBackendBase::getLocalCopy()
 373          */
 374         public function getLocalCopy( array $params ) {
 375                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 376                 return $this->backends[$this->masterIndex]->getLocalCopy( $realParams );
 377         }
 378
 379         /**
 380          * @see FileBackendBase::getFileList()
 381          */
 382         public function getFileList( array $params ) {
 383                 $realParams = $this->substOpPaths( $params, $this->backends[$this->masterIndex] );
 384                 return $this->backends[$this->masterIndex]->getFileList( $realParams );
 385         }
 386
 387         /**
 388          * @see FileBackendBase::clearCache()
 389          */
 390         public function clearCache( array $paths = null ) {
 391                 foreach ( $this->backends as $backend ) {
 392                         $realPaths = is_array( $paths ) ? $this->substPaths( $paths ) : null;
 393                         $backend->clearCache( $realPaths );
 394                 }
 395         }
 396 }