maintenance/includes/TextPassDumper.php

   1 <?php
   2 /**
   3  * BackupDumper that postprocesses XML dumps from dumpBackup.php to add page text
   4  *
   5  * Copyright (C) 2005 Brion Vibber <brion@pobox.com>
   6  * https://www.mediawiki.org/
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Dump
  25  * @ingroup Maintenance
  26  */
  27
  28 require_once __DIR__ . '/BackupDumper.php';
  29 require_once __DIR__ . '/SevenZipStream.php';
  30 require_once __DIR__ . '/../../includes/export/WikiExporter.php';
  31
  32 use MediaWiki\MediaWikiServices;
  33 use MediaWiki\Shell\Shell;
  34 use MediaWiki\Storage\BlobAccessException;
  35 use MediaWiki\Storage\SqlBlobStore;
  36 use Wikimedia\Rdbms\IMaintainableDatabase;
  37
  38 /**
  39  * @ingroup Maintenance
  40  */
  41 class TextPassDumper extends BackupDumper {
  42         /** @var BaseDump */
  43         public $prefetch = null;
  44         /** @var string|bool */
  45         private $thisPage;
  46         /** @var string|bool */
  47         private $thisRev;
  48
  49         // when we spend more than maxTimeAllowed seconds on this run, we continue
  50         // processing until we write out the next complete page, then save output file(s),
  51         // rename it/them and open new one(s)
  52         public $maxTimeAllowed = 0; // 0 = no limit
  53
  54         protected $input = "php://stdin";
  55         protected $history = WikiExporter::FULL;
  56         protected $fetchCount = 0;
  57         protected $prefetchCount = 0;
  58         protected $prefetchCountLast = 0;
  59         protected $fetchCountLast = 0;
  60
  61         protected $maxFailures = 5;
  62         protected $maxConsecutiveFailedTextRetrievals = 200;
  63         protected $failureTimeout = 5; // Seconds to sleep after db failure
  64
  65         protected $bufferSize = 524288; // In bytes. Maximum size to read from the stub in on go.
  66
  67         /** @var array */
  68         protected $php = [];
  69         protected $spawn = false;
  70
  71         /**
  72          * @var bool|resource
  73          */
  74         protected $spawnProc = false;
  75
  76         /**
  77          * @var resource
  78          */
  79         protected $spawnWrite;
  80
  81         /**
  82          * @var resource
  83          */
  84         protected $spawnRead;
  85
  86         /**
  87          * @var bool|resource
  88          */
  89         protected $spawnErr = false;
  90
  91         /**
  92          * @var bool|XmlDumpWriter
  93          */
  94         protected $xmlwriterobj = false;
  95
  96         protected $timeExceeded = false;
  97         protected $firstPageWritten = false;
  98         protected $lastPageWritten = false;
  99         protected $checkpointJustWritten = false;
 100         protected $checkpointFiles = [];
 101
 102         /**
 103          * @var IMaintainableDatabase
 104          */
 105         protected $db;
 106
 107         /**
 108          * @param array|null $args For backward compatibility
 109          */
 110         function __construct( $args = null ) {
 111                 parent::__construct();
 112
 113                 $this->addDescription( <<<TEXT
 114 This script postprocesses XML dumps from dumpBackup.php to add
 115 page text which was stubbed out (using --stub).
 116
 117 XML input is accepted on stdin.
 118 XML output is sent to stdout; progress reports are sent to stderr.
 119 TEXT
 120                 );
 121                 $this->stderr = fopen( "php://stderr", "wt" );
 122
 123                 $this->addOption( 'stub', 'To load a compressed stub dump instead of stdin. ' .
 124                         'Specify as --stub=<type>:<file>.', false, true );
 125                 $this->addOption( 'prefetch', 'Use a prior dump file as a text source, to savepressure on the ' .
 126                         'database. (Requires the XMLReader extension). Specify as --prefetch=<type>:<file>',
 127                         false, true );
 128                 $this->addOption( 'maxtime', 'Write out checkpoint file after this many minutes (writing' .
 129                         'out complete page, closing xml file properly, and opening new one' .
 130                         'with header).  This option requires the checkpointfile option.', false, true );
 131                 $this->addOption( 'checkpointfile', 'Use this string for checkpoint filenames,substituting ' .
 132                         'first pageid written for the first %s (required) and the last pageid written for the ' .
 133                         'second %s if it exists.', false, true, false, true ); // This can be specified multiple times
 134                 $this->addOption( 'quiet', 'Don\'t dump status reports to stderr.' );
 135                 $this->addOption( 'full', 'Dump all revisions of every page' );
 136                 $this->addOption( 'current', 'Base ETA on number of pages in database instead of all revisions' );
 137                 $this->addOption( 'spawn', 'Spawn a subprocess for loading text records, optionally specify ' .
 138                         'php[,mwscript] paths' );
 139                 $this->addOption( 'buffersize', 'Buffer size in bytes to use for reading the stub. ' .
 140                         '(Default: 512KB, Minimum: 4KB)', false, true );
 141
 142                 if ( $args ) {
 143                         $this->loadWithArgv( $args );
 144                         $this->processOptions();
 145                 }
 146         }
 147
 148         /**
 149          * @return SqlBlobStore
 150          */
 151         private function getBlobStore() {
 152                 return MediaWikiServices::getInstance()->getBlobStore();
 153         }
 154
 155         function execute() {
 156                 $this->processOptions();
 157                 $this->dump( true );
 158         }
 159
 160         function processOptions() {
 161                 parent::processOptions();
 162
 163                 if ( $this->hasOption( 'buffersize' ) ) {
 164                         $this->bufferSize = max( intval( $this->getOption( 'buffersize' ) ), 4 * 1024 );
 165                 }
 166
 167                 if ( $this->hasOption( 'prefetch' ) ) {
 168                         $url = $this->processFileOpt( $this->getOption( 'prefetch' ) );
 169                         $this->prefetch = new BaseDump( $url );
 170                 }
 171
 172                 if ( $this->hasOption( 'stub' ) ) {
 173                         $this->input = $this->processFileOpt( $this->getOption( 'stub' ) );
 174                 }
 175
 176                 if ( $this->hasOption( 'maxtime' ) ) {
 177                         $this->maxTimeAllowed = intval( $this->getOption( 'maxtime' ) ) * 60;
 178                 }
 179
 180                 if ( $this->hasOption( 'checkpointfile' ) ) {
 181                         $this->checkpointFiles = $this->getOption( 'checkpointfile' );
 182                 }
 183
 184                 if ( $this->hasOption( 'current' ) ) {
 185                         $this->history = WikiExporter::CURRENT;
 186                 }
 187
 188                 if ( $this->hasOption( 'full' ) ) {
 189                         $this->history = WikiExporter::FULL;
 190                 }
 191
 192                 if ( $this->hasOption( 'spawn' ) ) {
 193                         $this->spawn = true;
 194                         $val = $this->getOption( 'spawn' );
 195                         if ( $val !== 1 ) {
 196                                 $this->php = explode( ',', $val, 2 );
 197                         }
 198                 }
 199         }
 200
 201         /**
 202          * Drop the database connection $this->db and try to get a new one.
 203          *
 204          * This function tries to get a /different/ connection if this is
 205          * possible. Hence, (if this is possible) it switches to a different
 206          * failover upon each call.
 207          *
 208          * This function resets $this->lb and closes all connections on it.
 209          *
 210          * @throws MWException
 211          * @suppress PhanTypeObjectUnsetDeclaredProperty
 212          */
 213         function rotateDb() {
 214                 // Cleaning up old connections
 215                 if ( isset( $this->lb ) ) {
 216                         $this->lb->closeAll();
 217                         unset( $this->lb );
 218                 }
 219
 220                 if ( $this->forcedDb !== null ) {
 221                         $this->db = $this->forcedDb;
 222
 223                         return;
 224                 }
 225
 226                 if ( isset( $this->db ) && $this->db->isOpen() ) {
 227                         throw new MWException( 'DB is set and has not been closed by the Load Balancer' );
 228                 }
 229
 230                 unset( $this->db );
 231
 232                 // Trying to set up new connection.
 233                 // We do /not/ retry upon failure, but delegate to encapsulating logic, to avoid
 234                 // individually retrying at different layers of code.
 235
 236                 try {
 237                         $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 238                         $this->lb = $lbFactory->newMainLB();
 239                 } catch ( Exception $e ) {
 240                         throw new MWException( __METHOD__
 241                                 . " rotating DB failed to obtain new load balancer (" . $e->getMessage() . ")" );
 242                 }
 243
 244                 try {
 245                         $this->db = $this->lb->getMaintenanceConnectionRef( DB_REPLICA, 'dump' );
 246                 } catch ( Exception $e ) {
 247                         throw new MWException( __METHOD__
 248                                 . " rotating DB failed to obtain new database (" . $e->getMessage() . ")" );
 249                 }
 250         }
 251
 252         function initProgress( $history = WikiExporter::FULL ) {
 253                 parent::initProgress();
 254                 $this->timeOfCheckpoint = $this->startTime;
 255         }
 256
 257         function dump( $history, $text = WikiExporter::TEXT ) {
 258                 // Notice messages will foul up your XML output even if they're
 259                 // relatively harmless.
 260                 if ( ini_get( 'display_errors' ) ) {
 261                         ini_set( 'display_errors', 'stderr' );
 262                 }
 263
 264                 $this->initProgress( $this->history );
 265
 266                 // We are trying to get an initial database connection to avoid that the
 267                 // first try of this request's first call to getText fails. However, if
 268                 // obtaining a good DB connection fails it's not a serious issue, as
 269                 // getText does retry upon failure and can start without having a working
 270                 // DB connection.
 271                 try {
 272                         $this->rotateDb();
 273                 } catch ( Exception $e ) {
 274                         // We do not even count this as failure. Just let eventual
 275                         // watchdogs know.
 276                         $this->progress( "Getting initial DB connection failed (" .
 277                                 $e->getMessage() . ")" );
 278                 }
 279
 280                 $this->egress = new ExportProgressFilter( $this->sink, $this );
 281
 282                 // it would be nice to do it in the constructor, oh well. need egress set
 283                 $this->finalOptionCheck();
 284
 285                 // we only want this so we know how to close a stream :-P
 286                 $this->xmlwriterobj = new XmlDumpWriter( XmlDumpWriter::WRITE_CONTENT, $this->schemaVersion );
 287
 288                 $input = fopen( $this->input, "rt" );
 289                 $this->readDump( $input );
 290
 291                 if ( $this->spawnProc ) {
 292                         $this->closeSpawn();
 293                 }
 294
 295                 $this->report( true );
 296         }
 297
 298         function processFileOpt( $opt ) {
 299                 $split = explode( ':', $opt, 2 );
 300                 $val = $split[0];
 301                 $param = '';
 302                 if ( count( $split ) === 2 ) {
 303                         $param = $split[1];
 304                 }
 305                 $fileURIs = explode( ';', $param );
 306                 $newFileURIs = [];
 307                 foreach ( $fileURIs as $URI ) {
 308                         switch ( $val ) {
 309                                 case "file":
 310                                         $newURI = $URI;
 311                                         break;
 312                                 case "gzip":
 313                                         $newURI = "compress.zlib://$URI";
 314                                         break;
 315                                 case "bzip2":
 316                                         $newURI = "compress.bzip2://$URI";
 317                                         break;
 318                                 case "7zip":
 319                                         $newURI = "mediawiki.compress.7z://$URI";
 320                                         break;
 321                                 default:
 322                                         $newURI = $URI;
 323                         }
 324                         $newFileURIs[] = $newURI;
 325                 }
 326                 $val = implode( ';', $newFileURIs );
 327
 328                 return $val;
 329         }
 330
 331         /**
 332          * Overridden to include prefetch ratio if enabled.
 333          */
 334         function showReport() {
 335                 if ( !$this->prefetch ) {
 336                         parent::showReport();
 337
 338                         return;
 339                 }
 340
 341                 if ( $this->reporting ) {
 342                         $now = wfTimestamp( TS_DB );
 343                         $nowts = microtime( true );
 344                         $deltaAll = $nowts - $this->startTime;
 345                         $deltaPart = $nowts - $this->lastTime;
 346                         $this->pageCountPart = $this->pageCount - $this->pageCountLast;
 347                         $this->revCountPart = $this->revCount - $this->revCountLast;
 348
 349                         if ( $deltaAll ) {
 350                                 $portion = $this->revCount / $this->maxCount;
 351                                 $eta = $this->startTime + $deltaAll / $portion;
 352                                 $etats = wfTimestamp( TS_DB, intval( $eta ) );
 353                                 if ( $this->fetchCount ) {
 354                                         $fetchRate = 100.0 * $this->prefetchCount / $this->fetchCount;
 355                                 } else {
 356                                         $fetchRate = '-';
 357                                 }
 358                                 $pageRate = $this->pageCount / $deltaAll;
 359                                 $revRate = $this->revCount / $deltaAll;
 360                         } else {
 361                                 $pageRate = '-';
 362                                 $revRate = '-';
 363                                 $etats = '-';
 364                                 $fetchRate = '-';
 365                         }
 366                         if ( $deltaPart ) {
 367                                 if ( $this->fetchCountLast ) {
 368                                         $fetchRatePart = 100.0 * $this->prefetchCountLast / $this->fetchCountLast;
 369                                 } else {
 370                                         $fetchRatePart = '-';
 371                                 }
 372                                 $pageRatePart = $this->pageCountPart / $deltaPart;
 373                                 $revRatePart = $this->revCountPart / $deltaPart;
 374                         } else {
 375                                 $fetchRatePart = '-';
 376                                 $pageRatePart = '-';
 377                                 $revRatePart = '-';
 378                         }
 379
 380                         $dbDomain = WikiMap::getCurrentWikiDbDomain()->getId();
 381                         $this->progress( sprintf(
 382                                 "%s: %s (ID %d) %d pages (%0.1f|%0.1f/sec all|curr), "
 383                                         . "%d revs (%0.1f|%0.1f/sec all|curr), %0.1f%%|%0.1f%% "
 384                                         . "prefetched (all|curr), ETA %s [max %d]",
 385                                 $now, $dbDomain, $this->ID, $this->pageCount, $pageRate,
 386                                 $pageRatePart, $this->revCount, $revRate, $revRatePart,
 387                                 $fetchRate, $fetchRatePart, $etats, $this->maxCount
 388                         ) );
 389                         $this->lastTime = $nowts;
 390                         $this->revCountLast = $this->revCount;
 391                         $this->prefetchCountLast = $this->prefetchCount;
 392                         $this->fetchCountLast = $this->fetchCount;
 393                 }
 394         }
 395
 396         function setTimeExceeded() {
 397                 $this->timeExceeded = true;
 398         }
 399
 400         function checkIfTimeExceeded() {
 401                 if ( $this->maxTimeAllowed
 402                         && ( $this->lastTime - $this->timeOfCheckpoint > $this->maxTimeAllowed )
 403                 ) {
 404                         return true;
 405                 }
 406
 407                 return false;
 408         }
 409
 410         function finalOptionCheck() {
 411                 if ( ( $this->checkpointFiles && !$this->maxTimeAllowed )
 412                         || ( $this->maxTimeAllowed && !$this->checkpointFiles )
 413                 ) {
 414                         throw new MWException( "Options checkpointfile and maxtime must be specified together.\n" );
 415                 }
 416                 foreach ( $this->checkpointFiles as $checkpointFile ) {
 417                         $count = substr_count( $checkpointFile, "%s" );
 418                         if ( $count != 2 ) {
 419                                 throw new MWException( "Option checkpointfile must contain two '%s' "
 420                                         . "for substitution of first and last pageids, count is $count instead, "
 421                                         . "file is $checkpointFile.\n" );
 422                         }
 423                 }
 424
 425                 if ( $this->checkpointFiles ) {
 426                         $filenameList = (array)$this->egress->getFilenames();
 427                         if ( count( $filenameList ) != count( $this->checkpointFiles ) ) {
 428                                 throw new MWException( "One checkpointfile must be specified "
 429                                         . "for each output option, if maxtime is used.\n" );
 430                         }
 431                 }
 432         }
 433
 434         /**
 435          * @throws MWException Failure to parse XML input
 436          * @param resource $input
 437          * @return bool
 438          */
 439         function readDump( $input ) {
 440                 $this->buffer = "";
 441                 $this->openElement = false;
 442                 $this->atStart = true;
 443                 $this->state = "";
 444                 $this->lastName = "";
 445                 $this->thisPage = 0;
 446                 $this->thisRev = 0;
 447                 $this->thisRevModel = null;
 448                 $this->thisRevFormat = null;
 449
 450                 $parser = xml_parser_create( "UTF-8" );
 451                 xml_parser_set_option( $parser, XML_OPTION_CASE_FOLDING, false );
 452
 453                 xml_set_element_handler(
 454                         $parser,
 455                         [ $this, 'startElement' ],
 456                         [ $this, 'endElement' ]
 457                 );
 458                 xml_set_character_data_handler( $parser, [ $this, 'characterData' ] );
 459
 460                 $offset = 0; // for context extraction on error reporting
 461                 do {
 462                         if ( $this->checkIfTimeExceeded() ) {
 463                                 $this->setTimeExceeded();
 464                         }
 465                         $chunk = fread( $input, $this->bufferSize );
 466                         if ( !xml_parse( $parser, $chunk, feof( $input ) ) ) {
 467                                 wfDebug( "TextDumpPass::readDump encountered XML parsing error\n" );
 468
 469                                 $byte = xml_get_current_byte_index( $parser );
 470                                 $msg = wfMessage( 'xml-error-string',
 471                                         'XML import parse failure',
 472                                         xml_get_current_line_number( $parser ),
 473                                         xml_get_current_column_number( $parser ),
 474                                         $byte . ( is_null( $chunk ) ? null : ( '; "' . substr( $chunk, $byte - $offset, 16 ) . '"' ) ),
 475                                         xml_error_string( xml_get_error_code( $parser ) ) )->escaped();
 476
 477                                 xml_parser_free( $parser );
 478
 479                                 throw new MWException( $msg );
 480                         }
 481                         $offset += strlen( $chunk );
 482                 } while ( $chunk !== false && !feof( $input ) );
 483                 if ( $this->maxTimeAllowed ) {
 484                         $filenameList = (array)$this->egress->getFilenames();
 485                         // we wrote some stuff after last checkpoint that needs renamed
 486                         if ( file_exists( $filenameList[0] ) ) {
 487                                 $newFilenames = [];
 488                                 # we might have just written the header and footer and had no
 489                                 # pages or revisions written... perhaps they were all deleted
 490                                 # there's no pageID 0 so we use that. the caller is responsible
 491                                 # for deciding what to do with a file containing only the
 492                                 # siteinfo information and the mw tags.
 493                                 if ( !$this->firstPageWritten ) {
 494                                         $firstPageID = str_pad( 0, 9, "0", STR_PAD_LEFT );
 495                                         $lastPageID = str_pad( 0, 9, "0", STR_PAD_LEFT );
 496                                 } else {
 497                                         $firstPageID = str_pad( $this->firstPageWritten, 9, "0", STR_PAD_LEFT );
 498                                         $lastPageID = str_pad( $this->lastPageWritten, 9, "0", STR_PAD_LEFT );
 499                                 }
 500
 501                                 $filenameCount = count( $filenameList );
 502                                 for ( $i = 0; $i < $filenameCount; $i++ ) {
 503                                         $checkpointNameFilledIn = sprintf( $this->checkpointFiles[$i], $firstPageID, $lastPageID );
 504                                         $fileinfo = pathinfo( $filenameList[$i] );
 505                                         $newFilenames[] = $fileinfo['dirname'] . '/' . $checkpointNameFilledIn;
 506                                 }
 507                                 $this->egress->closeAndRename( $newFilenames );
 508                         }
 509                 }
 510                 xml_parser_free( $parser );
 511
 512                 return true;
 513         }
 514
 515         /**
 516          * Applies applicable export transformations to $text.
 517          *
 518          * @param string $text
 519          * @param string $model
 520          * @param string|null $format
 521          *
 522          * @return string
 523          */
 524         private function exportTransform( $text, $model, $format = null ) {
 525                 try {
 526                         $handler = ContentHandler::getForModelID( $model );
 527                         $text = $handler->exportTransform( $text, $format );
 528                 }
 529                 catch ( MWException $ex ) {
 530                         $this->progress(
 531                                 "Unable to apply export transformation for content model '$model': " .
 532                                 $ex->getMessage()
 533                         );
 534                 }
 535
 536                 return $text;
 537         }
 538
 539         /**
 540          * Tries to load revision text.
 541          * Export transformations are applied if the content model is given or can be
 542          * determined from the database.
 543          *
 544          * Upon errors, retries (Up to $this->maxFailures tries each call).
 545          * If still no good revision could be found even after this retrying, "" is returned.
 546          * If no good revision text could be returned for
 547          * $this->maxConsecutiveFailedTextRetrievals consecutive calls to getText, MWException
 548          * is thrown.
 549          *
 550          * @param int|string $id Content address, or text row ID.
 551          * @param string|bool|null $model The content model used to determine
 552          *  applicable export transformations.
 553          *  If $model is null, it will be determined from the database.
 554          * @param string|null $format The content format used when applying export transformations.
 555          *
 556          * @throws MWException
 557          * @return string The revision text for $id, or ""
 558          */
 559         function getText( $id, $model = null, $format = null ) {
 560                 global $wgContentHandlerUseDB;
 561
 562                 $prefetchNotTried = true; // Whether or not we already tried to get the text via prefetch.
 563                 $text = false; // The candidate for a good text. false if no proper value.
 564                 $failures = 0; // The number of times, this invocation of getText already failed.
 565
 566                 // The number of times getText failed without yielding a good text in between.
 567                 static $consecutiveFailedTextRetrievals = 0;
 568
 569                 $this->fetchCount++;
 570
 571                 // To allow to simply return on success and do not have to worry about book keeping,
 572                 // we assume, this fetch works (possible after some retries). Nevertheless, we koop
 573                 // the old value, so we can restore it, if problems occur (See after the while loop).
 574                 $oldConsecutiveFailedTextRetrievals = $consecutiveFailedTextRetrievals;
 575                 $consecutiveFailedTextRetrievals = 0;
 576
 577                 if ( $model === null && $wgContentHandlerUseDB ) {
 578                         // TODO: MCR: use content table
 579                         $row = $this->db->selectRow(
 580                                 'revision',
 581                                 [ 'rev_content_model', 'rev_content_format' ],
 582                                 [ 'rev_id' => $this->thisRev ],
 583                                 __METHOD__
 584                         );
 585
 586                         if ( $row ) {
 587                                 $model = $row->rev_content_model;
 588                                 $format = $row->rev_content_format;
 589                         }
 590                 }
 591
 592                 if ( $model === null || $model === '' ) {
 593                         $model = false;
 594                 }
 595
 596                 while ( $failures < $this->maxFailures ) {
 597                         // As soon as we found a good text for the $id, we will return immediately.
 598                         // Hence, if we make it past the try catch block, we know that we did not
 599                         // find a good text.
 600
 601                         try {
 602                                 // Step 1: Get some text (or reuse from previous iteratuon if checking
 603                                 //         for plausibility failed)
 604
 605                                 // Trying to get prefetch, if it has not been tried before
 606                                 if ( $text === false && isset( $this->prefetch ) && $prefetchNotTried ) {
 607                                         $prefetchNotTried = false;
 608                                         $tryIsPrefetch = true;
 609                                         $text = $this->prefetch->prefetch( (int)$this->thisPage, (int)$this->thisRev );
 610
 611                                         if ( $text === null ) {
 612                                                 $text = false;
 613                                         }
 614
 615                                         if ( is_string( $text ) && $model !== false ) {
 616                                                 // Apply export transformation to text coming from an old dump.
 617                                                 // The purpose of this transformation is to convert up from legacy
 618                                                 // formats, which may still be used in the older dump that is used
 619                                                 // for pre-fetching. Applying the transformation again should not
 620                                                 // interfere with content that is already in the correct form.
 621                                                 $text = $this->exportTransform( $text, $model, $format );
 622                                         }
 623                                 }
 624
 625                                 if ( $text === false ) {
 626                                         // Fallback to asking the database
 627                                         $tryIsPrefetch = false;
 628                                         if ( $this->spawn ) {
 629                                                 $text = $this->getTextSpawned( $id );
 630                                         } else {
 631                                                 $text = $this->getTextDb( $id );
 632                                         }
 633
 634                                         if ( $text !== false && $model !== false ) {
 635                                                 // Apply export transformation to text coming from the database.
 636                                                 // Prefetched text should already have transformations applied.
 637                                                 $text = $this->exportTransform( $text, $model, $format );
 638                                         }
 639
 640                                         // No more checks for texts from DB for now.
 641                                         // If we received something that is not false,
 642                                         // We treat it as good text, regardless of whether it actually is or is not
 643                                         if ( $text !== false ) {
 644                                                 return $text;
 645                                         }
 646                                 }
 647
 648                                 if ( $text === false ) {
 649                                         throw new MWException( "Generic error while obtaining text for id " . $id );
 650                                 }
 651
 652                                 // We received a good candidate for the text of $id via some method
 653
 654                                 // Step 2: Checking for plausibility and return the text if it is
 655                                 //         plausible
 656                                 $revID = intval( $this->thisRev );
 657                                 if ( !isset( $this->db ) ) {
 658                                         throw new MWException( "No database available" );
 659                                 }
 660
 661                                 if ( $model !== CONTENT_MODEL_WIKITEXT ) {
 662                                         $revLength = strlen( $text );
 663                                 } else {
 664                                         $revLength = $this->db->selectField( 'revision', 'rev_len', [ 'rev_id' => $revID ] );
 665                                 }
 666
 667                                 if ( strlen( $text ) == $revLength ) {
 668                                         if ( $tryIsPrefetch ) {
 669                                                 $this->prefetchCount++;
 670                                         }
 671
 672                                         return $text;
 673                                 }
 674
 675                                 $text = false;
 676                                 throw new MWException( "Received text is unplausible for id " . $id );
 677                         } catch ( Exception $e ) {
 678                                 $msg = "getting/checking text " . $id . " failed (" . $e->getMessage() . ")";
 679                                 if ( $failures + 1 < $this->maxFailures ) {
 680                                         $msg .= " (Will retry " . ( $this->maxFailures - $failures - 1 ) . " more times)";
 681                                 }
 682                                 $this->progress( $msg );
 683                         }
 684
 685                         // Something went wrong; we did not a text that was plausible :(
 686                         $failures++;
 687
 688                         // A failure in a prefetch hit does not warrant resetting db connection etc.
 689                         if ( !$tryIsPrefetch ) {
 690                                 // After backing off for some time, we try to reboot the whole process as
 691                                 // much as possible to not carry over failures from one part to the other
 692                                 // parts
 693                                 sleep( $this->failureTimeout );
 694                                 try {
 695                                         $this->rotateDb();
 696                                         if ( $this->spawn ) {
 697                                                 $this->closeSpawn();
 698                                                 $this->openSpawn();
 699                                         }
 700                                 } catch ( Exception $e ) {
 701                                         $this->progress( "Rebooting getText infrastructure failed (" . $e->getMessage() . ")" .
 702                                                 " Trying to continue anyways" );
 703                                 }
 704                         }
 705                 }
 706
 707                 // Retirieving a good text for $id failed (at least) maxFailures times.
 708                 // We abort for this $id.
 709
 710                 // Restoring the consecutive failures, and maybe aborting, if the dump
 711                 // is too broken.
 712                 $consecutiveFailedTextRetrievals = $oldConsecutiveFailedTextRetrievals + 1;
 713                 if ( $consecutiveFailedTextRetrievals > $this->maxConsecutiveFailedTextRetrievals ) {
 714                         throw new MWException( "Graceful storage failure" );
 715                 }
 716
 717                 return "";
 718         }
 719
 720         /**
 721          * Loads the serialized content from storage.
 722          *
 723          * @param int|string $id Content address, or text row ID.
 724          * @return bool|string
 725          */
 726         private function getTextDb( $id ) {
 727                 $store = $this->getBlobStore();
 728                 $address = ( is_int( $id ) || strpos( $id, ':' ) === false )
 729                         ? SqlBlobStore::makeAddressFromTextId( (int)$id )
 730                         : $id;
 731
 732                 try {
 733                         $text = $store->getBlob( $address );
 734
 735                         $stripped = str_replace( "\r", "", $text );
 736                         $normalized = MediaWikiServices::getInstance()->getContentLanguage()
 737                                 ->normalize( $stripped );
 738
 739                         return $normalized;
 740                 } catch ( BlobAccessException $ex ) {
 741                         // XXX: log a warning?
 742                         return false;
 743                 }
 744         }
 745
 746         /**
 747          * @param int|string $address Content address, or text row ID.
 748          * @return bool|string
 749          */
 750         private function getTextSpawned( $address ) {
 751                 Wikimedia\suppressWarnings();
 752                 if ( !$this->spawnProc ) {
 753                         // First time?
 754                         $this->openSpawn();
 755                 }
 756                 $text = $this->getTextSpawnedOnce( $address );
 757                 Wikimedia\restoreWarnings();
 758
 759                 return $text;
 760         }
 761
 762         function openSpawn() {
 763                 global $IP;
 764
 765                 $wiki = WikiMap::getWikiIdFromDbDomain( WikiMap::getCurrentWikiDbDomain() );
 766                 if ( count( $this->php ) == 2 ) {
 767                         $mwscriptpath = $this->php[1];
 768                 } else {
 769                         $mwscriptpath = "$IP/../multiversion/MWScript.php";
 770                 }
 771                 if ( file_exists( $mwscriptpath ) ) {
 772                         $cmd = implode( " ",
 773                                 array_map( [ Shell::class, 'escape' ],
 774                                         [
 775                                                 $this->php[0],
 776                                                 $mwscriptpath,
 777                                                 "fetchText.php",
 778                                                 '--wiki', $wiki ] ) );
 779                 } else {
 780                         $cmd = implode( " ",
 781                                 array_map( [ Shell::class, 'escape' ],
 782                                         [
 783                                                 $this->php[0],
 784                                                 "$IP/maintenance/fetchText.php",
 785                                                 '--wiki', $wiki ] ) );
 786                 }
 787                 $spec = [
 788                         0 => [ "pipe", "r" ],
 789                         1 => [ "pipe", "w" ],
 790                         2 => [ "file", "/dev/null", "a" ] ];
 791                 $pipes = [];
 792
 793                 $this->progress( "Spawning database subprocess: $cmd" );
 794                 $this->spawnProc = proc_open( $cmd, $spec, $pipes );
 795                 if ( !$this->spawnProc ) {
 796                         $this->progress( "Subprocess spawn failed." );
 797
 798                         return false;
 799                 }
 800                 list(
 801                         $this->spawnWrite, // -> stdin
 802                         $this->spawnRead, // <- stdout
 803                 ) = $pipes;
 804
 805                 return true;
 806         }
 807
 808         private function closeSpawn() {
 809                 Wikimedia\suppressWarnings();
 810                 if ( $this->spawnRead ) {
 811                         fclose( $this->spawnRead );
 812                 }
 813                 $this->spawnRead = null;
 814                 if ( $this->spawnWrite ) {
 815                         fclose( $this->spawnWrite );
 816                 }
 817                 $this->spawnWrite = null;
 818                 if ( $this->spawnErr ) {
 819                         fclose( $this->spawnErr );
 820                 }
 821                 $this->spawnErr = false;
 822                 if ( $this->spawnProc ) {
 823                         pclose( $this->spawnProc );
 824                 }
 825                 $this->spawnProc = false;
 826                 Wikimedia\restoreWarnings();
 827         }
 828
 829         /**
 830          * @param int|string $address Content address, or text row ID.
 831          * @return bool|string
 832          */
 833         private function getTextSpawnedOnce( $address ) {
 834                 if ( is_int( $address ) || intval( $address ) ) {
 835                         $address = SqlBlobStore::makeAddressFromTextId( (int)$address );
 836                 }
 837
 838                 $ok = fwrite( $this->spawnWrite, "$address\n" );
 839                 // $this->progress( ">> $id" );
 840                 if ( !$ok ) {
 841                         return false;
 842                 }
 843
 844                 $ok = fflush( $this->spawnWrite );
 845                 // $this->progress( ">> [flush]" );
 846                 if ( !$ok ) {
 847                         return false;
 848                 }
 849
 850                 // check that the text address they are sending is the one we asked for
 851                 // this avoids out of sync revision text errors we have encountered in the past
 852                 $newAddress = fgets( $this->spawnRead );
 853                 if ( $newAddress === false ) {
 854                         return false;
 855                 }
 856                 $newAddress = trim( $newAddress );
 857                 if ( strpos( $newAddress, ':' ) === false ) {
 858                         $newAddress = SqlBlobStore::makeAddressFromTextId( intval( $newAddress ) );
 859                 }
 860
 861                 if ( $newAddress !== $address ) {
 862                         return false;
 863                 }
 864
 865                 $len = fgets( $this->spawnRead );
 866                 // $this->progress( "<< " . trim( $len ) );
 867                 if ( $len === false ) {
 868                         return false;
 869                 }
 870
 871                 $nbytes = intval( $len );
 872                 // actual error, not zero-length text
 873                 if ( $nbytes < 0 ) {
 874                         return false;
 875                 }
 876
 877                 $text = "";
 878
 879                 // Subprocess may not send everything at once, we have to loop.
 880                 while ( $nbytes > strlen( $text ) ) {
 881                         $buffer = fread( $this->spawnRead, $nbytes - strlen( $text ) );
 882                         if ( $buffer === false ) {
 883                                 break;
 884                         }
 885                         $text .= $buffer;
 886                 }
 887
 888                 $gotbytes = strlen( $text );
 889                 if ( $gotbytes != $nbytes ) {
 890                         $this->progress( "Expected $nbytes bytes from database subprocess, got $gotbytes " );
 891
 892                         return false;
 893                 }
 894
 895                 // Do normalization in the dump thread...
 896                 $stripped = str_replace( "\r", "", $text );
 897                 $normalized = MediaWikiServices::getInstance()->getContentLanguage()->
 898                         normalize( $stripped );
 899
 900                 return $normalized;
 901         }
 902
 903         function startElement( $parser, $name, $attribs ) {
 904                 $this->checkpointJustWritten = false;
 905
 906                 $this->clearOpenElement( null );
 907                 $this->lastName = $name;
 908
 909                 if ( $name == 'revision' ) {
 910                         $this->state = $name;
 911                         $this->egress->writeOpenPage( null, $this->buffer );
 912                         $this->buffer = "";
 913                 } elseif ( $name == 'page' ) {
 914                         $this->state = $name;
 915                         if ( $this->atStart ) {
 916                                 $this->egress->writeOpenStream( $this->buffer );
 917                                 $this->buffer = "";
 918                                 $this->atStart = false;
 919                         }
 920                 }
 921
 922                 if ( $name == "text" && isset( $attribs['id'] ) ) {
 923                         $id = $attribs['id'];
 924                         $model = trim( $this->thisRevModel );
 925                         $format = trim( $this->thisRevFormat );
 926
 927                         $model = $model === '' ? null : $model;
 928                         $format = $format === '' ? null : $format;
 929
 930                         $text = $this->getText( $id, $model, $format );
 931                         $this->openElement = [ $name, [ 'xml:space' => 'preserve' ] ];
 932                         if ( strlen( $text ) > 0 ) {
 933                                 $this->characterData( $parser, $text );
 934                         }
 935                 } else {
 936                         $this->openElement = [ $name, $attribs ];
 937                 }
 938         }
 939
 940         function endElement( $parser, $name ) {
 941                 $this->checkpointJustWritten = false;
 942
 943                 if ( $this->openElement ) {
 944                         $this->clearOpenElement( "" );
 945                 } else {
 946                         $this->buffer .= "</$name>";
 947                 }
 948
 949                 if ( $name == 'revision' ) {
 950                         $this->egress->writeRevision( null, $this->buffer );
 951                         $this->buffer = "";
 952                         $this->thisRev = "";
 953                         $this->thisRevModel = null;
 954                         $this->thisRevFormat = null;
 955                 } elseif ( $name == 'page' ) {
 956                         if ( !$this->firstPageWritten ) {
 957                                 $this->firstPageWritten = trim( $this->thisPage );
 958                         }
 959                         $this->lastPageWritten = trim( $this->thisPage );
 960                         if ( $this->timeExceeded ) {
 961                                 $this->egress->writeClosePage( $this->buffer );
 962                                 // nasty hack, we can't just write the chardata after the
 963                                 // page tag, it will include leading blanks from the next line
 964                                 $this->egress->sink->write( "\n" );
 965
 966                                 $this->buffer = $this->xmlwriterobj->closeStream();
 967                                 $this->egress->writeCloseStream( $this->buffer );
 968
 969                                 $this->buffer = "";
 970                                 $this->thisPage = "";
 971                                 // this could be more than one file if we had more than one output arg
 972
 973                                 $filenameList = (array)$this->egress->getFilenames();
 974                                 $newFilenames = [];
 975                                 $firstPageID = str_pad( $this->firstPageWritten, 9, "0", STR_PAD_LEFT );
 976                                 $lastPageID = str_pad( $this->lastPageWritten, 9, "0", STR_PAD_LEFT );
 977                                 $filenamesCount = count( $filenameList );
 978                                 for ( $i = 0; $i < $filenamesCount; $i++ ) {
 979                                         $checkpointNameFilledIn = sprintf( $this->checkpointFiles[$i], $firstPageID, $lastPageID );
 980                                         $fileinfo = pathinfo( $filenameList[$i] );
 981                                         $newFilenames[] = $fileinfo['dirname'] . '/' . $checkpointNameFilledIn;
 982                                 }
 983                                 $this->egress->closeRenameAndReopen( $newFilenames );
 984                                 $this->buffer = $this->xmlwriterobj->openStream();
 985                                 $this->timeExceeded = false;
 986                                 $this->timeOfCheckpoint = $this->lastTime;
 987                                 $this->firstPageWritten = false;
 988                                 $this->checkpointJustWritten = true;
 989                         } else {
 990                                 $this->egress->writeClosePage( $this->buffer );
 991                                 $this->buffer = "";
 992                                 $this->thisPage = "";
 993                         }
 994                 } elseif ( $name == 'mediawiki' ) {
 995                         $this->egress->writeCloseStream( $this->buffer );
 996                         $this->buffer = "";
 997                 }
 998         }
 999
1000         function characterData( $parser, $data ) {
1001                 $this->clearOpenElement( null );
1002                 if ( $this->lastName == "id" ) {
1003                         if ( $this->state == "revision" ) {
1004                                 $this->thisRev .= $data;
1005                         } elseif ( $this->state == "page" ) {
1006                                 $this->thisPage .= $data;
1007                         }
1008                 } elseif ( $this->lastName == "model" ) {
1009                         $this->thisRevModel .= $data;
1010                 } elseif ( $this->lastName == "format" ) {
1011                         $this->thisRevFormat .= $data;
1012                 }
1013
1014                 // have to skip the newline left over from closepagetag line of
1015                 // end of checkpoint files. nasty hack!!
1016                 if ( $this->checkpointJustWritten ) {
1017                         if ( $data[0] == "\n" ) {
1018                                 $data = substr( $data, 1 );
1019                         }
1020                         $this->checkpointJustWritten = false;
1021                 }
1022                 $this->buffer .= htmlspecialchars( $data );
1023         }
1024
1025         function clearOpenElement( $style ) {
1026                 if ( $this->openElement ) {
1027                         $this->buffer .= Xml::element( $this->openElement[0], $this->openElement[1], $style );
1028                         $this->openElement = false;
1029                 }
1030         }
1031 }