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