maintenance/backupTextPass.inc

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