includes/libs/filebackend/fileop/FileOp.php

   1 <?php
   2 /**
   3  * Helper class for representing operations with transaction support.
   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 use Psr\Log\LoggerInterface;
  25
  26 /**
  27  * FileBackend helper class for representing operations.
  28  * Do not use this class from places outside FileBackend.
  29  *
  30  * Methods called from FileOpBatch::attempt() should avoid throwing
  31  * exceptions at all costs. FileOp objects should be lightweight in order
  32  * to support large arrays in memory and serialization.
  33  *
  34  * @ingroup FileBackend
  35  * @since 1.19
  36  */
  37 abstract class FileOp {
  38         /** @var array */
  39         protected $params = [];
  40
  41         /** @var FileBackendStore */
  42         protected $backend;
  43         /** @var LoggerInterface */
  44         protected $logger;
  45
  46         /** @var int */
  47         protected $state = self::STATE_NEW;
  48
  49         /** @var bool */
  50         protected $failed = false;
  51
  52         /** @var bool */
  53         protected $async = false;
  54
  55         /** @var string */
  56         protected $batchId;
  57
  58         /** @var bool Operation is not a no-op */
  59         protected $doOperation = true;
  60
  61         /** @var string */
  62         protected $sourceSha1;
  63
  64         /** @var bool */
  65         protected $overwriteSameCase;
  66
  67         /** @var bool */
  68         protected $destExists;
  69
  70         /* Object life-cycle */
  71         const STATE_NEW = 1;
  72         const STATE_CHECKED = 2;
  73         const STATE_ATTEMPTED = 3;
  74
  75         /**
  76          * Build a new batch file operation transaction
  77          *
  78          * @param FileBackendStore $backend
  79          * @param array $params
  80          * @param LoggerInterface $logger PSR logger instance
  81          * @throws FileBackendError
  82          */
  83         final public function __construct(
  84                 FileBackendStore $backend, array $params, LoggerInterface $logger
  85         ) {
  86                 $this->backend = $backend;
  87                 $this->logger = $logger;
  88                 list( $required, $optional, $paths ) = $this->allowedParams();
  89                 foreach ( $required as $name ) {
  90                         if ( isset( $params[$name] ) ) {
  91                                 $this->params[$name] = $params[$name];
  92                         } else {
  93                                 throw new InvalidArgumentException( "File operation missing parameter '$name'." );
  94                         }
  95                 }
  96                 foreach ( $optional as $name ) {
  97                         if ( isset( $params[$name] ) ) {
  98                                 $this->params[$name] = $params[$name];
  99                         }
 100                 }
 101                 foreach ( $paths as $name ) {
 102                         if ( isset( $this->params[$name] ) ) {
 103                                 // Normalize paths so the paths to the same file have the same string
 104                                 $this->params[$name] = self::normalizeIfValidStoragePath( $this->params[$name] );
 105                         }
 106                 }
 107         }
 108
 109         /**
 110          * Normalize a string if it is a valid storage path
 111          *
 112          * @param string $path
 113          * @return string
 114          */
 115         protected static function normalizeIfValidStoragePath( $path ) {
 116                 if ( FileBackend::isStoragePath( $path ) ) {
 117                         $res = FileBackend::normalizeStoragePath( $path );
 118
 119                         return ( $res !== null ) ? $res : $path;
 120                 }
 121
 122                 return $path;
 123         }
 124
 125         /**
 126          * Set the batch UUID this operation belongs to
 127          *
 128          * @param string $batchId
 129          */
 130         final public function setBatchId( $batchId ) {
 131                 $this->batchId = $batchId;
 132         }
 133
 134         /**
 135          * Get the value of the parameter with the given name
 136          *
 137          * @param string $name
 138          * @return mixed Returns null if the parameter is not set
 139          */
 140         final public function getParam( $name ) {
 141                 return isset( $this->params[$name] ) ? $this->params[$name] : null;
 142         }
 143
 144         /**
 145          * Check if this operation failed precheck() or attempt()
 146          *
 147          * @return bool
 148          */
 149         final public function failed() {
 150                 return $this->failed;
 151         }
 152
 153         /**
 154          * Get a new empty predicates array for precheck()
 155          *
 156          * @return array
 157          */
 158         final public static function newPredicates() {
 159                 return [ 'exists' => [], 'sha1' => [] ];
 160         }
 161
 162         /**
 163          * Get a new empty dependency tracking array for paths read/written to
 164          *
 165          * @return array
 166          */
 167         final public static function newDependencies() {
 168                 return [ 'read' => [], 'write' => [] ];
 169         }
 170
 171         /**
 172          * Update a dependency tracking array to account for this operation
 173          *
 174          * @param array $deps Prior path reads/writes; format of FileOp::newPredicates()
 175          * @return array
 176          */
 177         final public function applyDependencies( array $deps ) {
 178                 $deps['read'] += array_fill_keys( $this->storagePathsRead(), 1 );
 179                 $deps['write'] += array_fill_keys( $this->storagePathsChanged(), 1 );
 180
 181                 return $deps;
 182         }
 183
 184         /**
 185          * Check if this operation changes files listed in $paths
 186          *
 187          * @param array $deps Prior path reads/writes; format of FileOp::newPredicates()
 188          * @return bool
 189          */
 190         final public function dependsOn( array $deps ) {
 191                 foreach ( $this->storagePathsChanged() as $path ) {
 192                         if ( isset( $deps['read'][$path] ) || isset( $deps['write'][$path] ) ) {
 193                                 return true; // "output" or "anti" dependency
 194                         }
 195                 }
 196                 foreach ( $this->storagePathsRead() as $path ) {
 197                         if ( isset( $deps['write'][$path] ) ) {
 198                                 return true; // "flow" dependency
 199                         }
 200                 }
 201
 202                 return false;
 203         }
 204
 205         /**
 206          * Get the file journal entries for this file operation
 207          *
 208          * @param array $oPredicates Pre-op info about files (format of FileOp::newPredicates)
 209          * @param array $nPredicates Post-op info about files (format of FileOp::newPredicates)
 210          * @return array
 211          */
 212         final public function getJournalEntries( array $oPredicates, array $nPredicates ) {
 213                 if ( !$this->doOperation ) {
 214                         return []; // this is a no-op
 215                 }
 216                 $nullEntries = [];
 217                 $updateEntries = [];
 218                 $deleteEntries = [];
 219                 $pathsUsed = array_merge( $this->storagePathsRead(), $this->storagePathsChanged() );
 220                 foreach ( array_unique( $pathsUsed ) as $path ) {
 221                         $nullEntries[] = [ // assertion for recovery
 222                                 'op' => 'null',
 223                                 'path' => $path,
 224                                 'newSha1' => $this->fileSha1( $path, $oPredicates )
 225                         ];
 226                 }
 227                 foreach ( $this->storagePathsChanged() as $path ) {
 228                         if ( $nPredicates['sha1'][$path] === false ) { // deleted
 229                                 $deleteEntries[] = [
 230                                         'op' => 'delete',
 231                                         'path' => $path,
 232                                         'newSha1' => ''
 233                                 ];
 234                         } else { // created/updated
 235                                 $updateEntries[] = [
 236                                         'op' => $this->fileExists( $path, $oPredicates ) ? 'update' : 'create',
 237                                         'path' => $path,
 238                                         'newSha1' => $nPredicates['sha1'][$path]
 239                                 ];
 240                         }
 241                 }
 242
 243                 return array_merge( $nullEntries, $updateEntries, $deleteEntries );
 244         }
 245
 246         /**
 247          * Check preconditions of the operation without writing anything.
 248          * This must update $predicates for each path that the op can change
 249          * except when a failing StatusValue object is returned.
 250          *
 251          * @param array $predicates
 252          * @return StatusValue
 253          */
 254         final public function precheck( array &$predicates ) {
 255                 if ( $this->state !== self::STATE_NEW ) {
 256                         return StatusValue::newFatal( 'fileop-fail-state', self::STATE_NEW, $this->state );
 257                 }
 258                 $this->state = self::STATE_CHECKED;
 259                 $status = $this->doPrecheck( $predicates );
 260                 if ( !$status->isOK() ) {
 261                         $this->failed = true;
 262                 }
 263
 264                 return $status;
 265         }
 266
 267         /**
 268          * @param array $predicates
 269          * @return StatusValue
 270          */
 271         protected function doPrecheck( array &$predicates ) {
 272                 return StatusValue::newGood();
 273         }
 274
 275         /**
 276          * Attempt the operation
 277          *
 278          * @return StatusValue
 279          */
 280         final public function attempt() {
 281                 if ( $this->state !== self::STATE_CHECKED ) {
 282                         return StatusValue::newFatal( 'fileop-fail-state', self::STATE_CHECKED, $this->state );
 283                 } elseif ( $this->failed ) { // failed precheck
 284                         return StatusValue::newFatal( 'fileop-fail-attempt-precheck' );
 285                 }
 286                 $this->state = self::STATE_ATTEMPTED;
 287                 if ( $this->doOperation ) {
 288                         $status = $this->doAttempt();
 289                         if ( !$status->isOK() ) {
 290                                 $this->failed = true;
 291                                 $this->logFailure( 'attempt' );
 292                         }
 293                 } else { // no-op
 294                         $status = StatusValue::newGood();
 295                 }
 296
 297                 return $status;
 298         }
 299
 300         /**
 301          * @return StatusValue
 302          */
 303         protected function doAttempt() {
 304                 return StatusValue::newGood();
 305         }
 306
 307         /**
 308          * Attempt the operation in the background
 309          *
 310          * @return StatusValue
 311          */
 312         final public function attemptAsync() {
 313                 $this->async = true;
 314                 $result = $this->attempt();
 315                 $this->async = false;
 316
 317                 return $result;
 318         }
 319
 320         /**
 321          * Get the file operation parameters
 322          *
 323          * @return array (required params list, optional params list, list of params that are paths)
 324          */
 325         protected function allowedParams() {
 326                 return [ [], [], [] ];
 327         }
 328
 329         /**
 330          * Adjust params to FileBackendStore internal file calls
 331          *
 332          * @param array $params
 333          * @return array (required params list, optional params list)
 334          */
 335         protected function setFlags( array $params ) {
 336                 return [ 'async' => $this->async ] + $params;
 337         }
 338
 339         /**
 340          * Get a list of storage paths read from for this operation
 341          *
 342          * @return array
 343          */
 344         public function storagePathsRead() {
 345                 return [];
 346         }
 347
 348         /**
 349          * Get a list of storage paths written to for this operation
 350          *
 351          * @return array
 352          */
 353         public function storagePathsChanged() {
 354                 return [];
 355         }
 356
 357         /**
 358          * Check for errors with regards to the destination file already existing.
 359          * Also set the destExists, overwriteSameCase and sourceSha1 member variables.
 360          * A bad StatusValue will be returned if there is no chance it can be overwritten.
 361          *
 362          * @param array $predicates
 363          * @return StatusValue
 364          */
 365         protected function precheckDestExistence( array $predicates ) {
 366                 $status = StatusValue::newGood();
 367                 // Get hash of source file/string and the destination file
 368                 $this->sourceSha1 = $this->getSourceSha1Base36(); // FS file or data string
 369                 if ( $this->sourceSha1 === null ) { // file in storage?
 370                         $this->sourceSha1 = $this->fileSha1( $this->params['src'], $predicates );
 371                 }
 372                 $this->overwriteSameCase = false;
 373                 $this->destExists = $this->fileExists( $this->params['dst'], $predicates );
 374                 if ( $this->destExists ) {
 375                         if ( $this->getParam( 'overwrite' ) ) {
 376                                 return $status; // OK
 377                         } elseif ( $this->getParam( 'overwriteSame' ) ) {
 378                                 $dhash = $this->fileSha1( $this->params['dst'], $predicates );
 379                                 // Check if hashes are valid and match each other...
 380                                 if ( !strlen( $this->sourceSha1 ) || !strlen( $dhash ) ) {
 381                                         $status->fatal( 'backend-fail-hashes' );
 382                                 } elseif ( $this->sourceSha1 !== $dhash ) {
 383                                         // Give an error if the files are not identical
 384                                         $status->fatal( 'backend-fail-notsame', $this->params['dst'] );
 385                                 } else {
 386                                         $this->overwriteSameCase = true; // OK
 387                                 }
 388
 389                                 return $status; // do nothing; either OK or bad status
 390                         } else {
 391                                 $status->fatal( 'backend-fail-alreadyexists', $this->params['dst'] );
 392
 393                                 return $status;
 394                         }
 395                 }
 396
 397                 return $status;
 398         }
 399
 400         /**
 401          * precheckDestExistence() helper function to get the source file SHA-1.
 402          * Subclasses should overwride this if the source is not in storage.
 403          *
 404          * @return string|bool Returns false on failure
 405          */
 406         protected function getSourceSha1Base36() {
 407                 return null; // N/A
 408         }
 409
 410         /**
 411          * Check if a file will exist in storage when this operation is attempted
 412          *
 413          * @param string $source Storage path
 414          * @param array $predicates
 415          * @return bool
 416          */
 417         final protected function fileExists( $source, array $predicates ) {
 418                 if ( isset( $predicates['exists'][$source] ) ) {
 419                         return $predicates['exists'][$source]; // previous op assures this
 420                 } else {
 421                         $params = [ 'src' => $source, 'latest' => true ];
 422
 423                         return $this->backend->fileExists( $params );
 424                 }
 425         }
 426
 427         /**
 428          * Get the SHA-1 of a file in storage when this operation is attempted
 429          *
 430          * @param string $source Storage path
 431          * @param array $predicates
 432          * @return string|bool False on failure
 433          */
 434         final protected function fileSha1( $source, array $predicates ) {
 435                 if ( isset( $predicates['sha1'][$source] ) ) {
 436                         return $predicates['sha1'][$source]; // previous op assures this
 437                 } elseif ( isset( $predicates['exists'][$source] ) && !$predicates['exists'][$source] ) {
 438                         return false; // previous op assures this
 439                 } else {
 440                         $params = [ 'src' => $source, 'latest' => true ];
 441
 442                         return $this->backend->getFileSha1Base36( $params );
 443                 }
 444         }
 445
 446         /**
 447          * Get the backend this operation is for
 448          *
 449          * @return FileBackendStore
 450          */
 451         public function getBackend() {
 452                 return $this->backend;
 453         }
 454
 455         /**
 456          * Log a file operation failure and preserve any temp files
 457          *
 458          * @param string $action
 459          */
 460         final public function logFailure( $action ) {
 461                 $params = $this->params;
 462                 $params['failedAction'] = $action;
 463                 try {
 464                         $this->logger->error( get_class( $this ) .
 465                                 " failed (batch #{$this->batchId}): " . FormatJson::encode( $params ) );
 466                 } catch ( Exception $e ) {
 467                         // bad config? debug log error?
 468                 }
 469         }
 470 }