maintenance/storage/recompressTracked.php

   1 <?php
   2 /**
   3  * Moves blobs indexed by trackBlobs.php to a specified list of destination
   4  * clusters, and recompresses them in the process.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  19  * http://www.gnu.org/copyleft/gpl.html
  20  *
  21  * @file
  22  * @ingroup Maintenance ExternalStorage
  23  */
  24
  25 use MediaWiki\Logger\LegacyLogger;
  26 use MediaWiki\MediaWikiServices;
  27 use MediaWiki\Shell\Shell;
  28 use Wikimedia\Rdbms\IDatabase;
  29
  30 $optionsWithArgs = RecompressTracked::getOptionsWithArgs();
  31 require __DIR__ . '/../commandLine.inc';
  32
  33 if ( count( $args ) < 1 ) {
  34         echo "Usage: php recompressTracked.php [options] <cluster> [... <cluster>...]
  35 Moves blobs indexed by trackBlobs.php to a specified list of destination clusters,
  36 and recompresses them in the process. Restartable.
  37
  38 Options:
  39         --procs <procs>       Set the number of child processes (default 1)
  40         --copy-only           Copy only, do not update the text table. Restart
  41                               without this option to complete.
  42         --debug-log <file>    Log debugging data to the specified file
  43         --info-log <file>     Log progress messages to the specified file
  44         --critical-log <file> Log error messages to the specified file
  45 ";
  46         exit( 1 );
  47 }
  48
  49 $job = RecompressTracked::newFromCommandLine( $args, $options );
  50 $job->execute();
  51
  52 /**
  53  * Maintenance script that moves blobs indexed by trackBlobs.php to a specified
  54  * list of destination clusters, and recompresses them in the process.
  55  *
  56  * @ingroup Maintenance ExternalStorage
  57  */
  58 class RecompressTracked {
  59         public $destClusters;
  60         public $batchSize = 1000;
  61         public $orphanBatchSize = 1000;
  62         public $reportingInterval = 10;
  63         public $numProcs = 1;
  64         public $numBatches = 0;
  65         public $pageBlobClass, $orphanBlobClass;
  66         public $replicaPipes, $replicaProcs, $prevReplicaId;
  67         public $copyOnly = false;
  68         public $isChild = false;
  69         public $replicaId = false;
  70         public $noCount = false;
  71         public $debugLog, $infoLog, $criticalLog;
  72         /** @var ExternalStoreDB */
  73         public $store;
  74
  75         private static $optionsWithArgs = [
  76                 'procs',
  77                 'replica-id',
  78                 'debug-log',
  79                 'info-log',
  80                 'critical-log'
  81         ];
  82
  83         private static $cmdLineOptionMap = [
  84                 'no-count' => 'noCount',
  85                 'procs' => 'numProcs',
  86                 'copy-only' => 'copyOnly',
  87                 'child' => 'isChild',
  88                 'replica-id' => 'replicaId',
  89                 'debug-log' => 'debugLog',
  90                 'info-log' => 'infoLog',
  91                 'critical-log' => 'criticalLog',
  92         ];
  93
  94         static function getOptionsWithArgs() {
  95                 return self::$optionsWithArgs;
  96         }
  97
  98         static function newFromCommandLine( $args, $options ) {
  99                 $jobOptions = [ 'destClusters' => $args ];
 100                 foreach ( self::$cmdLineOptionMap as $cmdOption => $classOption ) {
 101                         if ( isset( $options[$cmdOption] ) ) {
 102                                 $jobOptions[$classOption] = $options[$cmdOption];
 103                         }
 104                 }
 105
 106                 return new self( $jobOptions );
 107         }
 108
 109         function __construct( $options ) {
 110                 foreach ( $options as $name => $value ) {
 111                         $this->$name = $value;
 112                 }
 113                 $esFactory = MediaWikiServices::getInstance()->getExternalStoreFactory();
 114                 $this->store = $esFactory->getStore( 'DB' );
 115                 if ( !$this->isChild ) {
 116                         $GLOBALS['wgDebugLogPrefix'] = "RCT M: ";
 117                 } elseif ( $this->replicaId !== false ) {
 118                         $GLOBALS['wgDebugLogPrefix'] = "RCT {$this->replicaId}: ";
 119                 }
 120                 $this->pageBlobClass = function_exists( 'xdiff_string_bdiff' ) ?
 121                         DiffHistoryBlob::class : ConcatenatedGzipHistoryBlob::class;
 122                 $this->orphanBlobClass = ConcatenatedGzipHistoryBlob::class;
 123         }
 124
 125         function debug( $msg ) {
 126                 wfDebug( "$msg\n" );
 127                 if ( $this->debugLog ) {
 128                         $this->logToFile( $msg, $this->debugLog );
 129                 }
 130         }
 131
 132         function info( $msg ) {
 133                 echo "$msg\n";
 134                 if ( $this->infoLog ) {
 135                         $this->logToFile( $msg, $this->infoLog );
 136                 }
 137         }
 138
 139         function critical( $msg ) {
 140                 echo "$msg\n";
 141                 if ( $this->criticalLog ) {
 142                         $this->logToFile( $msg, $this->criticalLog );
 143                 }
 144         }
 145
 146         function logToFile( $msg, $file ) {
 147                 $header = '[' . date( 'd\TH:i:s' ) . '] ' . wfHostname() . ' ' . posix_getpid();
 148                 if ( $this->replicaId !== false ) {
 149                         $header .= "({$this->replicaId})";
 150                 }
 151                 $header .= ' ' . wfWikiID();
 152                 LegacyLogger::emit( sprintf( "%-50s %s\n", $header, $msg ), $file );
 153         }
 154
 155         /**
 156          * Wait until the selected replica DB has caught up to the master.
 157          * This allows us to use the replica DB for things that were committed in a
 158          * previous part of this batch process.
 159          */
 160         function syncDBs() {
 161                 $dbw = wfGetDB( DB_MASTER );
 162                 $dbr = wfGetDB( DB_REPLICA );
 163                 $pos = $dbw->getMasterPos();
 164                 $dbr->masterPosWait( $pos, 100000 );
 165         }
 166
 167         /**
 168          * Execute parent or child depending on the isChild option
 169          */
 170         function execute() {
 171                 if ( $this->isChild ) {
 172                         $this->executeChild();
 173                 } else {
 174                         $this->executeParent();
 175                 }
 176         }
 177
 178         /**
 179          * Execute the parent process
 180          */
 181         function executeParent() {
 182                 if ( !$this->checkTrackingTable() ) {
 183                         return;
 184                 }
 185
 186                 $this->syncDBs();
 187                 $this->startReplicaProcs();
 188                 $this->doAllPages();
 189                 $this->doAllOrphans();
 190                 $this->killReplicaProcs();
 191         }
 192
 193         /**
 194          * Make sure the tracking table exists and isn't empty
 195          * @return bool
 196          */
 197         function checkTrackingTable() {
 198                 $dbr = wfGetDB( DB_REPLICA );
 199                 if ( !$dbr->tableExists( 'blob_tracking' ) ) {
 200                         $this->critical( "Error: blob_tracking table does not exist" );
 201
 202                         return false;
 203                 }
 204                 $row = $dbr->selectRow( 'blob_tracking', '*', '', __METHOD__ );
 205                 if ( !$row ) {
 206                         $this->info( "Warning: blob_tracking table contains no rows, skipping this wiki." );
 207
 208                         return false;
 209                 }
 210
 211                 return true;
 212         }
 213
 214         /**
 215          * Start the worker processes.
 216          * These processes will listen on stdin for commands.
 217          * This necessary because text recompression is slow: loading, compressing and
 218          * writing are all slow.
 219          */
 220         function startReplicaProcs() {
 221                 $cmd = 'php ' . Shell::escape( __FILE__ );
 222                 foreach ( self::$cmdLineOptionMap as $cmdOption => $classOption ) {
 223                         if ( $cmdOption == 'replica-id' ) {
 224                                 continue;
 225                         } elseif ( in_array( $cmdOption, self::$optionsWithArgs ) && isset( $this->$classOption ) ) {
 226                                 $cmd .= " --$cmdOption " . Shell::escape( $this->$classOption );
 227                         } elseif ( $this->$classOption ) {
 228                                 $cmd .= " --$cmdOption";
 229                         }
 230                 }
 231                 $cmd .= ' --child' .
 232                         ' --wiki ' . Shell::escape( wfWikiID() ) .
 233                         ' ' . Shell::escape( ...$this->destClusters );
 234
 235                 $this->replicaPipes = $this->replicaProcs = [];
 236                 for ( $i = 0; $i < $this->numProcs; $i++ ) {
 237                         $pipes = [];
 238                         $spec = [
 239                                 [ 'pipe', 'r' ],
 240                                 [ 'file', 'php://stdout', 'w' ],
 241                                 [ 'file', 'php://stderr', 'w' ]
 242                         ];
 243                         Wikimedia\suppressWarnings();
 244                         $proc = proc_open( "$cmd --replica-id $i", $spec, $pipes );
 245                         Wikimedia\restoreWarnings();
 246                         if ( !$proc ) {
 247                                 $this->critical( "Error opening replica DB process: $cmd" );
 248                                 exit( 1 );
 249                         }
 250                         $this->replicaProcs[$i] = $proc;
 251                         $this->replicaPipes[$i] = $pipes[0];
 252                 }
 253                 $this->prevReplicaId = -1;
 254         }
 255
 256         /**
 257          * Gracefully terminate the child processes
 258          */
 259         function killReplicaProcs() {
 260                 $this->info( "Waiting for replica DB processes to finish..." );
 261                 for ( $i = 0; $i < $this->numProcs; $i++ ) {
 262                         $this->dispatchToReplica( $i, 'quit' );
 263                 }
 264                 for ( $i = 0; $i < $this->numProcs; $i++ ) {
 265                         $status = proc_close( $this->replicaProcs[$i] );
 266                         if ( $status ) {
 267                                 $this->critical( "Warning: child #$i exited with status $status" );
 268                         }
 269                 }
 270                 $this->info( "Done." );
 271         }
 272
 273         /**
 274          * Dispatch a command to the next available replica DB.
 275          * This may block until a replica DB finishes its work and becomes available.
 276          */
 277         function dispatch( ...$args ) {
 278                 $pipes = $this->replicaPipes;
 279                 $x = [];
 280                 $y = [];
 281                 $numPipes = stream_select( $x, $pipes, $y, 3600 );
 282                 if ( !$numPipes ) {
 283                         $this->critical( "Error waiting to write to replica DBs. Aborting" );
 284                         exit( 1 );
 285                 }
 286                 for ( $i = 0; $i < $this->numProcs; $i++ ) {
 287                         $replicaId = ( $i + $this->prevReplicaId + 1 ) % $this->numProcs;
 288                         if ( isset( $pipes[$replicaId] ) ) {
 289                                 $this->prevReplicaId = $replicaId;
 290                                 $this->dispatchToReplica( $replicaId, $args );
 291
 292                                 return;
 293                         }
 294                 }
 295                 $this->critical( "Unreachable" );
 296                 exit( 1 );
 297         }
 298
 299         /**
 300          * Dispatch a command to a specified replica DB
 301          * @param int $replicaId
 302          * @param array|string $args
 303          */
 304         function dispatchToReplica( $replicaId, $args ) {
 305                 $args = (array)$args;
 306                 $cmd = implode( ' ', $args );
 307                 fwrite( $this->replicaPipes[$replicaId], "$cmd\n" );
 308         }
 309
 310         /**
 311          * Move all tracked pages to the new clusters
 312          */
 313         function doAllPages() {
 314                 $dbr = wfGetDB( DB_REPLICA );
 315                 $i = 0;
 316                 $startId = 0;
 317                 if ( $this->noCount ) {
 318                         $numPages = '[unknown]';
 319                 } else {
 320                         $numPages = $dbr->selectField( 'blob_tracking',
 321                                 'COUNT(DISTINCT bt_page)',
 322                                 # A condition is required so that this query uses the index
 323                                 [ 'bt_moved' => 0 ],
 324                                 __METHOD__
 325                         );
 326                 }
 327                 if ( $this->copyOnly ) {
 328                         $this->info( "Copying pages..." );
 329                 } else {
 330                         $this->info( "Moving pages..." );
 331                 }
 332                 while ( true ) {
 333                         $res = $dbr->select( 'blob_tracking',
 334                                 [ 'bt_page' ],
 335                                 [
 336                                         'bt_moved' => 0,
 337                                         'bt_page > ' . $dbr->addQuotes( $startId )
 338                                 ],
 339                                 __METHOD__,
 340                                 [
 341                                         'DISTINCT',
 342                                         'ORDER BY' => 'bt_page',
 343                                         'LIMIT' => $this->batchSize,
 344                                 ]
 345                         );
 346                         if ( !$res->numRows() ) {
 347                                 break;
 348                         }
 349                         foreach ( $res as $row ) {
 350                                 $startId = $row->bt_page;
 351                                 $this->dispatch( 'doPage', $row->bt_page );
 352                                 $i++;
 353                         }
 354                         $this->report( 'pages', $i, $numPages );
 355                 }
 356                 $this->report( 'pages', $i, $numPages );
 357                 if ( $this->copyOnly ) {
 358                         $this->info( "All page copies queued." );
 359                 } else {
 360                         $this->info( "All page moves queued." );
 361                 }
 362         }
 363
 364         /**
 365          * Display a progress report
 366          * @param string $label
 367          * @param int $current
 368          * @param int $end
 369          */
 370         function report( $label, $current, $end ) {
 371                 $this->numBatches++;
 372                 if ( $current == $end || $this->numBatches >= $this->reportingInterval ) {
 373                         $this->numBatches = 0;
 374                         $this->info( "$label: $current / $end" );
 375                         MediaWikiServices::getInstance()->getDBLoadBalancerFactory()->waitForReplication();
 376                 }
 377         }
 378
 379         /**
 380          * Move all orphan text to the new clusters
 381          */
 382         function doAllOrphans() {
 383                 $dbr = wfGetDB( DB_REPLICA );
 384                 $startId = 0;
 385                 $i = 0;
 386                 if ( $this->noCount ) {
 387                         $numOrphans = '[unknown]';
 388                 } else {
 389                         $numOrphans = $dbr->selectField( 'blob_tracking',
 390                                 'COUNT(DISTINCT bt_text_id)',
 391                                 [ 'bt_moved' => 0, 'bt_page' => 0 ],
 392                                 __METHOD__ );
 393                         if ( !$numOrphans ) {
 394                                 return;
 395                         }
 396                 }
 397                 if ( $this->copyOnly ) {
 398                         $this->info( "Copying orphans..." );
 399                 } else {
 400                         $this->info( "Moving orphans..." );
 401                 }
 402
 403                 while ( true ) {
 404                         $res = $dbr->select( 'blob_tracking',
 405                                 [ 'bt_text_id' ],
 406                                 [
 407                                         'bt_moved' => 0,
 408                                         'bt_page' => 0,
 409                                         'bt_text_id > ' . $dbr->addQuotes( $startId )
 410                                 ],
 411                                 __METHOD__,
 412                                 [
 413                                         'DISTINCT',
 414                                         'ORDER BY' => 'bt_text_id',
 415                                         'LIMIT' => $this->batchSize
 416                                 ]
 417                         );
 418                         if ( !$res->numRows() ) {
 419                                 break;
 420                         }
 421                         $ids = [];
 422                         foreach ( $res as $row ) {
 423                                 $startId = $row->bt_text_id;
 424                                 $ids[] = $row->bt_text_id;
 425                                 $i++;
 426                         }
 427                         // Need to send enough orphan IDs to the child at a time to fill a blob,
 428                         // so orphanBatchSize needs to be at least ~100.
 429                         // batchSize can be smaller or larger.
 430                         while ( count( $ids ) > $this->orphanBatchSize ) {
 431                                 $args = array_slice( $ids, 0, $this->orphanBatchSize );
 432                                 $ids = array_slice( $ids, $this->orphanBatchSize );
 433                                 array_unshift( $args, 'doOrphanList' );
 434                                 $this->dispatch( ...$args );
 435                         }
 436                         if ( count( $ids ) ) {
 437                                 $args = $ids;
 438                                 array_unshift( $args, 'doOrphanList' );
 439                                 $this->dispatch( ...$args );
 440                         }
 441
 442                         $this->report( 'orphans', $i, $numOrphans );
 443                 }
 444                 $this->report( 'orphans', $i, $numOrphans );
 445                 $this->info( "All orphans queued." );
 446         }
 447
 448         /**
 449          * Main entry point for worker processes
 450          */
 451         function executeChild() {
 452                 $this->debug( 'starting' );
 453                 $this->syncDBs();
 454
 455                 while ( !feof( STDIN ) ) {
 456                         $line = rtrim( fgets( STDIN ) );
 457                         if ( $line == '' ) {
 458                                 continue;
 459                         }
 460                         $this->debug( $line );
 461                         $args = explode( ' ', $line );
 462                         $cmd = array_shift( $args );
 463                         switch ( $cmd ) {
 464                                 case 'doPage':
 465                                         $this->doPage( intval( $args[0] ) );
 466                                         break;
 467                                 case 'doOrphanList':
 468                                         $this->doOrphanList( array_map( 'intval', $args ) );
 469                                         break;
 470                                 case 'quit':
 471                                         return;
 472                         }
 473                         MediaWikiServices::getInstance()->getDBLoadBalancerFactory()->waitForReplication();
 474                 }
 475         }
 476
 477         /**
 478          * Move tracked text in a given page
 479          *
 480          * @param int $pageId
 481          */
 482         function doPage( $pageId ) {
 483                 $title = Title::newFromID( $pageId );
 484                 if ( $title ) {
 485                         $titleText = $title->getPrefixedText();
 486                 } else {
 487                         $titleText = '[deleted]';
 488                 }
 489                 $dbr = wfGetDB( DB_REPLICA );
 490
 491                 // Finish any incomplete transactions
 492                 if ( !$this->copyOnly ) {
 493                         $this->finishIncompleteMoves( [ 'bt_page' => $pageId ] );
 494                         $this->syncDBs();
 495                 }
 496
 497                 $startId = 0;
 498                 $trx = new CgzCopyTransaction( $this, $this->pageBlobClass );
 499
 500                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 501                 while ( true ) {
 502                         $res = $dbr->select(
 503                                 [ 'blob_tracking', 'text' ],
 504                                 '*',
 505                                 [
 506                                         'bt_page' => $pageId,
 507                                         'bt_text_id > ' . $dbr->addQuotes( $startId ),
 508                                         'bt_moved' => 0,
 509                                         'bt_new_url IS NULL',
 510                                         'bt_text_id=old_id',
 511                                 ],
 512                                 __METHOD__,
 513                                 [
 514                                         'ORDER BY' => 'bt_text_id',
 515                                         'LIMIT' => $this->batchSize
 516                                 ]
 517                         );
 518                         if ( !$res->numRows() ) {
 519                                 break;
 520                         }
 521
 522                         $lastTextId = 0;
 523                         foreach ( $res as $row ) {
 524                                 $startId = $row->bt_text_id;
 525                                 if ( $lastTextId == $row->bt_text_id ) {
 526                                         // Duplicate (null edit)
 527                                         continue;
 528                                 }
 529                                 $lastTextId = $row->bt_text_id;
 530                                 // Load the text
 531                                 $text = Revision::getRevisionText( $row );
 532                                 if ( $text === false ) {
 533                                         $this->critical( "Error loading {$row->bt_rev_id}/{$row->bt_text_id}" );
 534                                         continue;
 535                                 }
 536
 537                                 // Queue it
 538                                 if ( !$trx->addItem( $text, $row->bt_text_id ) ) {
 539                                         $this->debug( "$titleText: committing blob with " . $trx->getSize() . " items" );
 540                                         $trx->commit();
 541                                         $trx = new CgzCopyTransaction( $this, $this->pageBlobClass );
 542                                         $lbFactory->waitForReplication();
 543                                 }
 544                         }
 545                 }
 546
 547                 $this->debug( "$titleText: committing blob with " . $trx->getSize() . " items" );
 548                 $trx->commit();
 549         }
 550
 551         /**
 552          * Atomic move operation.
 553          *
 554          * Write the new URL to the text table and set the bt_moved flag.
 555          *
 556          * This is done in a single transaction to provide restartable behavior
 557          * without data loss.
 558          *
 559          * The transaction is kept short to reduce locking.
 560          *
 561          * @param int $textId
 562          * @param string $url
 563          */
 564         function moveTextRow( $textId, $url ) {
 565                 if ( $this->copyOnly ) {
 566                         $this->critical( "Internal error: can't call moveTextRow() in --copy-only mode" );
 567                         exit( 1 );
 568                 }
 569                 $dbw = wfGetDB( DB_MASTER );
 570                 $dbw->begin( __METHOD__ );
 571                 $dbw->update( 'text',
 572                         [ // set
 573                                 'old_text' => $url,
 574                                 'old_flags' => 'external,utf-8',
 575                         ],
 576                         [ // where
 577                                 'old_id' => $textId
 578                         ],
 579                         __METHOD__
 580                 );
 581                 $dbw->update( 'blob_tracking',
 582                         [ 'bt_moved' => 1 ],
 583                         [ 'bt_text_id' => $textId ],
 584                         __METHOD__
 585                 );
 586                 $dbw->commit( __METHOD__ );
 587         }
 588
 589         /**
 590          * Moves are done in two phases: bt_new_url and then bt_moved.
 591          *  - bt_new_url indicates that the text has been copied to the new cluster.
 592          *  - bt_moved indicates that the text table has been updated.
 593          *
 594          * This function completes any moves that only have done bt_new_url. This
 595          * can happen when the script is interrupted, or when --copy-only is used.
 596          *
 597          * @param array $conds
 598          */
 599         function finishIncompleteMoves( $conds ) {
 600                 $dbr = wfGetDB( DB_REPLICA );
 601                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 602
 603                 $startId = 0;
 604                 $conds = array_merge( $conds, [
 605                         'bt_moved' => 0,
 606                         'bt_new_url IS NOT NULL'
 607                 ] );
 608                 while ( true ) {
 609                         $res = $dbr->select( 'blob_tracking',
 610                                 '*',
 611                                 array_merge( $conds, [ 'bt_text_id > ' . $dbr->addQuotes( $startId ) ] ),
 612                                 __METHOD__,
 613                                 [
 614                                         'ORDER BY' => 'bt_text_id',
 615                                         'LIMIT' => $this->batchSize,
 616                                 ]
 617                         );
 618                         if ( !$res->numRows() ) {
 619                                 break;
 620                         }
 621                         $this->debug( 'Incomplete: ' . $res->numRows() . ' rows' );
 622                         foreach ( $res as $row ) {
 623                                 $startId = $row->bt_text_id;
 624                                 $this->moveTextRow( $row->bt_text_id, $row->bt_new_url );
 625                                 if ( $row->bt_text_id % 10 == 0 ) {
 626                                         $lbFactory->waitForReplication();
 627                                 }
 628                         }
 629                 }
 630         }
 631
 632         /**
 633          * Returns the name of the next target cluster
 634          * @return string
 635          */
 636         function getTargetCluster() {
 637                 $cluster = next( $this->destClusters );
 638                 if ( $cluster === false ) {
 639                         $cluster = reset( $this->destClusters );
 640                 }
 641
 642                 return $cluster;
 643         }
 644
 645         /**
 646          * Gets a DB master connection for the given external cluster name
 647          * @param string $cluster
 648          * @return IDatabase
 649          */
 650         function getExtDB( $cluster ) {
 651                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 652                 $lb = $lbFactory->getExternalLB( $cluster );
 653
 654                 return $lb->getConnection( DB_MASTER );
 655         }
 656
 657         /**
 658          * Move an orphan text_id to the new cluster
 659          *
 660          * @param array $textIds
 661          */
 662         function doOrphanList( $textIds ) {
 663                 // Finish incomplete moves
 664                 if ( !$this->copyOnly ) {
 665                         $this->finishIncompleteMoves( [ 'bt_text_id' => $textIds ] );
 666                         $this->syncDBs();
 667                 }
 668
 669                 $trx = new CgzCopyTransaction( $this, $this->orphanBlobClass );
 670
 671                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 672                 $res = wfGetDB( DB_REPLICA )->select(
 673                         [ 'text', 'blob_tracking' ],
 674                         [ 'old_id', 'old_text', 'old_flags' ],
 675                         [
 676                                 'old_id' => $textIds,
 677                                 'bt_text_id=old_id',
 678                                 'bt_moved' => 0,
 679                         ],
 680                         __METHOD__,
 681                         [ 'DISTINCT' ]
 682                 );
 683
 684                 foreach ( $res as $row ) {
 685                         $text = Revision::getRevisionText( $row );
 686                         if ( $text === false ) {
 687                                 $this->critical( "Error: cannot load revision text for old_id={$row->old_id}" );
 688                                 continue;
 689                         }
 690
 691                         if ( !$trx->addItem( $text, $row->old_id ) ) {
 692                                 $this->debug( "[orphan]: committing blob with " . $trx->getSize() . " rows" );
 693                                 $trx->commit();
 694                                 $trx = new CgzCopyTransaction( $this, $this->orphanBlobClass );
 695                                 $lbFactory->waitForReplication();
 696                         }
 697                 }
 698                 $this->debug( "[orphan]: committing blob with " . $trx->getSize() . " rows" );
 699                 $trx->commit();
 700         }
 701 }
 702
 703 /**
 704  * Class to represent a recompression operation for a single CGZ blob
 705  */
 706 class CgzCopyTransaction {
 707         /** @var RecompressTracked */
 708         public $parent;
 709         public $blobClass;
 710         /** @var ConcatenatedGzipHistoryBlob */
 711         public $cgz;
 712         public $referrers;
 713
 714         /**
 715          * Create a transaction from a RecompressTracked object
 716          * @param RecompressTracked $parent
 717          * @param string $blobClass
 718          */
 719         function __construct( $parent, $blobClass ) {
 720                 $this->blobClass = $blobClass;
 721                 $this->cgz = false;
 722                 $this->texts = [];
 723                 $this->parent = $parent;
 724         }
 725
 726         /**
 727          * Add text.
 728          * Returns false if it's ready to commit.
 729          * @param string $text
 730          * @param int $textId
 731          * @return bool
 732          */
 733         function addItem( $text, $textId ) {
 734                 if ( !$this->cgz ) {
 735                         $class = $this->blobClass;
 736                         $this->cgz = new $class;
 737                 }
 738                 $hash = $this->cgz->addItem( $text );
 739                 $this->referrers[$textId] = $hash;
 740                 $this->texts[$textId] = $text;
 741
 742                 return $this->cgz->isHappy();
 743         }
 744
 745         function getSize() {
 746                 return count( $this->texts );
 747         }
 748
 749         /**
 750          * Recompress text after some aberrant modification
 751          */
 752         function recompress() {
 753                 $class = $this->blobClass;
 754                 $this->cgz = new $class;
 755                 $this->referrers = [];
 756                 foreach ( $this->texts as $textId => $text ) {
 757                         $hash = $this->cgz->addItem( $text );
 758                         $this->referrers[$textId] = $hash;
 759                 }
 760         }
 761
 762         /**
 763          * Commit the blob.
 764          * Does nothing if no text items have been added.
 765          * May skip the move if --copy-only is set.
 766          */
 767         function commit() {
 768                 $originalCount = count( $this->texts );
 769                 if ( !$originalCount ) {
 770                         return;
 771                 }
 772
 773                 /* Check to see if the target text_ids have been moved already.
 774                  *
 775                  * We originally read from the replica DB, so this can happen when a single
 776                  * text_id is shared between multiple pages. It's rare, but possible
 777                  * if a delete/move/undelete cycle splits up a null edit.
 778                  *
 779                  * We do a locking read to prevent closer-run race conditions.
 780                  */
 781                 $dbw = wfGetDB( DB_MASTER );
 782                 $dbw->begin( __METHOD__ );
 783                 $res = $dbw->select( 'blob_tracking',
 784                         [ 'bt_text_id', 'bt_moved' ],
 785                         [ 'bt_text_id' => array_keys( $this->referrers ) ],
 786                         __METHOD__, [ 'FOR UPDATE' ] );
 787                 $dirty = false;
 788                 foreach ( $res as $row ) {
 789                         if ( $row->bt_moved ) {
 790                                 # This row has already been moved, remove it
 791                                 $this->parent->debug( "TRX: conflict detected in old_id={$row->bt_text_id}" );
 792                                 unset( $this->texts[$row->bt_text_id] );
 793                                 $dirty = true;
 794                         }
 795                 }
 796
 797                 // Recompress the blob if necessary
 798                 if ( $dirty ) {
 799                         if ( !count( $this->texts ) ) {
 800                                 // All have been moved already
 801                                 if ( $originalCount > 1 ) {
 802                                         // This is suspcious, make noise
 803                                         $this->parent->critical(
 804                                                 "Warning: concurrent operation detected, are there two conflicting " .
 805                                                 "processes running, doing the same job?" );
 806                                 }
 807
 808                                 return;
 809                         }
 810                         $this->recompress();
 811                 }
 812
 813                 // Insert the data into the destination cluster
 814                 $targetCluster = $this->parent->getTargetCluster();
 815                 $store = $this->parent->store;
 816                 $targetDB = $store->getMaster( $targetCluster );
 817                 $targetDB->clearFlag( DBO_TRX ); // we manage the transactions
 818                 $targetDB->begin( __METHOD__ );
 819                 $baseUrl = $this->parent->store->store( $targetCluster, serialize( $this->cgz ) );
 820
 821                 // Write the new URLs to the blob_tracking table
 822                 foreach ( $this->referrers as $textId => $hash ) {
 823                         $url = $baseUrl . '/' . $hash;
 824                         $dbw->update( 'blob_tracking',
 825                                 [ 'bt_new_url' => $url ],
 826                                 [
 827                                         'bt_text_id' => $textId,
 828                                         'bt_moved' => 0, # Check for concurrent conflicting update
 829                                 ],
 830                                 __METHOD__
 831                         );
 832                 }
 833
 834                 $targetDB->commit( __METHOD__ );
 835                 // Critical section here: interruption at this point causes blob duplication
 836                 // Reversing the order of the commits would cause data loss instead
 837                 $dbw->commit( __METHOD__ );
 838
 839                 // Write the new URLs to the text table and set the moved flag
 840                 if ( !$this->parent->copyOnly ) {
 841                         foreach ( $this->referrers as $textId => $hash ) {
 842                                 $url = $baseUrl . '/' . $hash;
 843                                 $this->parent->moveTextRow( $textId, $url );
 844                         }
 845                 }
 846         }
 847 }