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\Storage\SqlBlobStore;
  26 use Wikimedia\Rdbms\IMaintainableDatabase;
  27 use MediaWiki\Logger\LegacyLogger;
  28 use MediaWiki\MediaWikiServices;
  29 use MediaWiki\Shell\Shell;
  30
  31 $optionsWithArgs = RecompressTracked::getOptionsWithArgs();
  32 require __DIR__ . '/../commandLine.inc';
  33
  34 if ( count( $args ) < 1 ) {
  35         echo "Usage: php recompressTracked.php [options] <cluster> [... <cluster>...]
  36 Moves blobs indexed by trackBlobs.php to a specified list of destination clusters,
  37 and recompresses them in the process. Restartable.
  38
  39 Options:
  40         --procs <procs>       Set the number of child processes (default 1)
  41         --copy-only           Copy only, do not update the text table. Restart
  42                               without this option to complete.
  43         --debug-log <file>    Log debugging data to the specified file
  44         --info-log <file>     Log progress messages to the specified file
  45         --critical-log <file> Log error messages to the specified file
  46 ";
  47         exit( 1 );
  48 }
  49
  50 $job = RecompressTracked::newFromCommandLine( $args, $options );
  51 $job->execute();
  52
  53 /**
  54  * Maintenance script that moves blobs indexed by trackBlobs.php to a specified
  55  * list of destination clusters, and recompresses them in the process.
  56  *
  57  * @ingroup Maintenance ExternalStorage
  58  */
  59 class RecompressTracked {
  60         public $destClusters;
  61         public $batchSize = 1000;
  62         public $orphanBatchSize = 1000;
  63         public $reportingInterval = 10;
  64         public $numProcs = 1;
  65         public $numBatches = 0;
  66         public $pageBlobClass, $orphanBlobClass;
  67         public $childPipes, $childProcs, $prevChildId;
  68         public $copyOnly = false;
  69         public $isChild = false;
  70         public $childId = false;
  71         public $noCount = false;
  72         public $debugLog, $infoLog, $criticalLog;
  73         /** @var ExternalStoreDB */
  74         public $store;
  75         /** @var SqlBlobStore */
  76         private $blobStore;
  77
  78         private static $optionsWithArgs = [
  79                 'procs',
  80                 'child-id',
  81                 'debug-log',
  82                 'info-log',
  83                 'critical-log'
  84         ];
  85
  86         private static $cmdLineOptionMap = [
  87                 'no-count' => 'noCount',
  88                 'procs' => 'numProcs',
  89                 'copy-only' => 'copyOnly',
  90                 'child' => 'isChild',
  91                 'child-id' => 'childId',
  92                 'debug-log' => 'debugLog',
  93                 'info-log' => 'infoLog',
  94                 'critical-log' => 'criticalLog',
  95         ];
  96
  97         static function getOptionsWithArgs() {
  98                 return self::$optionsWithArgs;
  99         }
 100
 101         static function newFromCommandLine( $args, $options ) {
 102                 $jobOptions = [ 'destClusters' => $args ];
 103                 foreach ( self::$cmdLineOptionMap as $cmdOption => $classOption ) {
 104                         if ( isset( $options[$cmdOption] ) ) {
 105                                 $jobOptions[$classOption] = $options[$cmdOption];
 106                         }
 107                 }
 108
 109                 return new self( $jobOptions );
 110         }
 111
 112         function __construct( $options ) {
 113                 foreach ( $options as $name => $value ) {
 114                         $this->$name = $value;
 115                 }
 116                 $esFactory = MediaWikiServices::getInstance()->getExternalStoreFactory();
 117                 $this->store = $esFactory->getStore( 'DB' );
 118                 if ( !$this->isChild ) {
 119                         $GLOBALS['wgDebugLogPrefix'] = "RCT M: ";
 120                 } elseif ( $this->childId !== false ) {
 121                         $GLOBALS['wgDebugLogPrefix'] = "RCT {$this->childId}: ";
 122                 }
 123                 $this->pageBlobClass = function_exists( 'xdiff_string_bdiff' ) ?
 124                         DiffHistoryBlob::class : ConcatenatedGzipHistoryBlob::class;
 125                 $this->orphanBlobClass = ConcatenatedGzipHistoryBlob::class;
 126                 // @phan-suppress-next-line PhanAccessMethodInternal
 127                 $this->blobStore = MediaWikiServices::getInstance()
 128                         ->getBlobStoreFactory()
 129                         ->newSqlBlobStore();
 130         }
 131
 132         function debug( $msg ) {
 133                 wfDebug( "$msg\n" );
 134                 if ( $this->debugLog ) {
 135                         $this->logToFile( $msg, $this->debugLog );
 136                 }
 137         }
 138
 139         function info( $msg ) {
 140                 echo "$msg\n";
 141                 if ( $this->infoLog ) {
 142                         $this->logToFile( $msg, $this->infoLog );
 143                 }
 144         }
 145
 146         function critical( $msg ) {
 147                 echo "$msg\n";
 148                 if ( $this->criticalLog ) {
 149                         $this->logToFile( $msg, $this->criticalLog );
 150                 }
 151         }
 152
 153         function logToFile( $msg, $file ) {
 154                 $header = '[' . date( 'd\TH:i:s' ) . '] ' . wfHostname() . ' ' . posix_getpid();
 155                 if ( $this->childId !== false ) {
 156                         $header .= "({$this->childId})";
 157                 }
 158                 $header .= ' ' . WikiMap::getCurrentWikiDbDomain()->getId();
 159                 LegacyLogger::emit( sprintf( "%-50s %s\n", $header, $msg ), $file );
 160         }
 161
 162         /**
 163          * Wait until the selected replica DB has caught up to the master.
 164          * This allows us to use the replica DB for things that were committed in a
 165          * previous part of this batch process.
 166          */
 167         function syncDBs() {
 168                 $dbw = wfGetDB( DB_MASTER );
 169                 $dbr = wfGetDB( DB_REPLICA );
 170                 $pos = $dbw->getMasterPos();
 171                 $dbr->masterPosWait( $pos, 100000 );
 172         }
 173
 174         /**
 175          * Execute parent or child depending on the isChild option
 176          */
 177         function execute() {
 178                 if ( $this->isChild ) {
 179                         $this->executeChild();
 180                 } else {
 181                         $this->executeParent();
 182                 }
 183         }
 184
 185         /**
 186          * Execute the parent process
 187          */
 188         function executeParent() {
 189                 if ( !$this->checkTrackingTable() ) {
 190                         return;
 191                 }
 192
 193                 $this->syncDBs();
 194                 $this->startChildProcs();
 195                 $this->doAllPages();
 196                 $this->doAllOrphans();
 197                 $this->killChildProcs();
 198         }
 199
 200         /**
 201          * Make sure the tracking table exists and isn't empty
 202          * @return bool
 203          */
 204         function checkTrackingTable() {
 205                 $dbr = wfGetDB( DB_REPLICA );
 206                 if ( !$dbr->tableExists( 'blob_tracking' ) ) {
 207                         $this->critical( "Error: blob_tracking table does not exist" );
 208
 209                         return false;
 210                 }
 211                 $row = $dbr->selectRow( 'blob_tracking', '*', '', __METHOD__ );
 212                 if ( !$row ) {
 213                         $this->info( "Warning: blob_tracking table contains no rows, skipping this wiki." );
 214
 215                         return false;
 216                 }
 217
 218                 return true;
 219         }
 220
 221         /**
 222          * Start the worker processes.
 223          * These processes will listen on stdin for commands.
 224          * This necessary because text recompression is slow: loading, compressing and
 225          * writing are all slow.
 226          */
 227         function startChildProcs() {
 228                 $wiki = WikiMap::getWikiIdFromDbDomain( WikiMap::getCurrentWikiDbDomain() );
 229
 230                 $cmd = 'php ' . Shell::escape( __FILE__ );
 231                 foreach ( self::$cmdLineOptionMap as $cmdOption => $classOption ) {
 232                         if ( $cmdOption == 'child-id' ) {
 233                                 continue;
 234                         } elseif ( in_array( $cmdOption, self::$optionsWithArgs ) && isset( $this->$classOption ) ) {
 235                                 $cmd .= " --$cmdOption " . Shell::escape( $this->$classOption );
 236                         } elseif ( $this->$classOption ) {
 237                                 $cmd .= " --$cmdOption";
 238                         }
 239                 }
 240                 $cmd .= ' --child' .
 241                         ' --wiki ' . Shell::escape( $wiki ) .
 242                         ' ' . Shell::escape( ...$this->destClusters );
 243
 244                 $this->childPipes = $this->childProcs = [];
 245                 for ( $i = 0; $i < $this->numProcs; $i++ ) {
 246                         $pipes = [];
 247                         $spec = [
 248                                 [ 'pipe', 'r' ],
 249                                 [ 'file', 'php://stdout', 'w' ],
 250                                 [ 'file', 'php://stderr', 'w' ]
 251                         ];
 252                         Wikimedia\suppressWarnings();
 253                         $proc = proc_open( "$cmd --child-id $i", $spec, $pipes );
 254                         Wikimedia\restoreWarnings();
 255                         if ( !$proc ) {
 256                                 $this->critical( "Error opening child process: $cmd" );
 257                                 exit( 1 );
 258                         }
 259                         $this->childProcs[$i] = $proc;
 260                         $this->childPipes[$i] = $pipes[0];
 261                 }
 262                 $this->prevChildId = -1;
 263         }
 264
 265         /**
 266          * Gracefully terminate the child processes
 267          */
 268         function killChildProcs() {
 269                 $this->info( "Waiting for child processes to finish..." );
 270                 for ( $i = 0; $i < $this->numProcs; $i++ ) {
 271                         $this->dispatchToChild( $i, 'quit' );
 272                 }
 273                 for ( $i = 0; $i < $this->numProcs; $i++ ) {
 274                         $status = proc_close( $this->childProcs[$i] );
 275                         if ( $status ) {
 276                                 $this->critical( "Warning: child #$i exited with status $status" );
 277                         }
 278                 }
 279                 $this->info( "Done." );
 280         }
 281
 282         /**
 283          * Dispatch a command to the next available child process.
 284          * This may block until a child process finishes its work and becomes available.
 285          * @param array|string ...$args
 286          */
 287         function dispatch( ...$args ) {
 288                 $pipes = $this->childPipes;
 289                 $x = [];
 290                 $y = [];
 291                 $numPipes = stream_select( $x, $pipes, $y, 3600 );
 292                 if ( !$numPipes ) {
 293                         $this->critical( "Error waiting to write to child process. Aborting" );
 294                         exit( 1 );
 295                 }
 296                 for ( $i = 0; $i < $this->numProcs; $i++ ) {
 297                         $childId = ( $i + $this->prevChildId + 1 ) % $this->numProcs;
 298                         if ( isset( $pipes[$childId] ) ) {
 299                                 $this->prevChildId = $childId;
 300                                 $this->dispatchToChild( $childId, $args );
 301
 302                                 return;
 303                         }
 304                 }
 305                 $this->critical( "Unreachable" );
 306                 exit( 1 );
 307         }
 308
 309         /**
 310          * Dispatch a command to a specified child process
 311          * @param int $childId
 312          * @param array|string $args
 313          */
 314         function dispatchToChild( $childId, $args ) {
 315                 $args = (array)$args;
 316                 $cmd = implode( ' ', $args );
 317                 fwrite( $this->childPipes[$childId], "$cmd\n" );
 318         }
 319
 320         /**
 321          * Move all tracked pages to the new clusters
 322          */
 323         function doAllPages() {
 324                 $dbr = wfGetDB( DB_REPLICA );
 325                 $i = 0;
 326                 $startId = 0;
 327                 if ( $this->noCount ) {
 328                         $numPages = '[unknown]';
 329                 } else {
 330                         $numPages = $dbr->selectField( 'blob_tracking',
 331                                 'COUNT(DISTINCT bt_page)',
 332                                 # A condition is required so that this query uses the index
 333                                 [ 'bt_moved' => 0 ],
 334                                 __METHOD__
 335                         );
 336                 }
 337                 if ( $this->copyOnly ) {
 338                         $this->info( "Copying pages..." );
 339                 } else {
 340                         $this->info( "Moving pages..." );
 341                 }
 342                 while ( true ) {
 343                         $res = $dbr->select( 'blob_tracking',
 344                                 [ 'bt_page' ],
 345                                 [
 346                                         'bt_moved' => 0,
 347                                         'bt_page > ' . $dbr->addQuotes( $startId )
 348                                 ],
 349                                 __METHOD__,
 350                                 [
 351                                         'DISTINCT',
 352                                         'ORDER BY' => 'bt_page',
 353                                         'LIMIT' => $this->batchSize,
 354                                 ]
 355                         );
 356                         if ( !$res->numRows() ) {
 357                                 break;
 358                         }
 359                         foreach ( $res as $row ) {
 360                                 $startId = $row->bt_page;
 361                                 $this->dispatch( 'doPage', $row->bt_page );
 362                                 $i++;
 363                         }
 364                         $this->report( 'pages', $i, $numPages );
 365                 }
 366                 $this->report( 'pages', $i, $numPages );
 367                 if ( $this->copyOnly ) {
 368                         $this->info( "All page copies queued." );
 369                 } else {
 370                         $this->info( "All page moves queued." );
 371                 }
 372         }
 373
 374         /**
 375          * Display a progress report
 376          * @param string $label
 377          * @param int $current
 378          * @param int $end
 379          */
 380         function report( $label, $current, $end ) {
 381                 $this->numBatches++;
 382                 if ( $current == $end || $this->numBatches >= $this->reportingInterval ) {
 383                         $this->numBatches = 0;
 384                         $this->info( "$label: $current / $end" );
 385                         MediaWikiServices::getInstance()->getDBLoadBalancerFactory()->waitForReplication();
 386                 }
 387         }
 388
 389         /**
 390          * Move all orphan text to the new clusters
 391          */
 392         function doAllOrphans() {
 393                 $dbr = wfGetDB( DB_REPLICA );
 394                 $startId = 0;
 395                 $i = 0;
 396                 if ( $this->noCount ) {
 397                         $numOrphans = '[unknown]';
 398                 } else {
 399                         $numOrphans = $dbr->selectField( 'blob_tracking',
 400                                 'COUNT(DISTINCT bt_text_id)',
 401                                 [ 'bt_moved' => 0, 'bt_page' => 0 ],
 402                                 __METHOD__ );
 403                         if ( !$numOrphans ) {
 404                                 return;
 405                         }
 406                 }
 407                 if ( $this->copyOnly ) {
 408                         $this->info( "Copying orphans..." );
 409                 } else {
 410                         $this->info( "Moving orphans..." );
 411                 }
 412
 413                 while ( true ) {
 414                         $res = $dbr->select( 'blob_tracking',
 415                                 [ 'bt_text_id' ],
 416                                 [
 417                                         'bt_moved' => 0,
 418                                         'bt_page' => 0,
 419                                         'bt_text_id > ' . $dbr->addQuotes( $startId )
 420                                 ],
 421                                 __METHOD__,
 422                                 [
 423                                         'DISTINCT',
 424                                         'ORDER BY' => 'bt_text_id',
 425                                         'LIMIT' => $this->batchSize
 426                                 ]
 427                         );
 428                         if ( !$res->numRows() ) {
 429                                 break;
 430                         }
 431                         $ids = [];
 432                         foreach ( $res as $row ) {
 433                                 $startId = $row->bt_text_id;
 434                                 $ids[] = $row->bt_text_id;
 435                                 $i++;
 436                         }
 437                         // Need to send enough orphan IDs to the child at a time to fill a blob,
 438                         // so orphanBatchSize needs to be at least ~100.
 439                         // batchSize can be smaller or larger.
 440                         while ( count( $ids ) > $this->orphanBatchSize ) {
 441                                 $args = array_slice( $ids, 0, $this->orphanBatchSize );
 442                                 $ids = array_slice( $ids, $this->orphanBatchSize );
 443                                 array_unshift( $args, 'doOrphanList' );
 444                                 $this->dispatch( ...$args );
 445                         }
 446                         if ( count( $ids ) ) {
 447                                 $args = $ids;
 448                                 array_unshift( $args, 'doOrphanList' );
 449                                 $this->dispatch( ...$args );
 450                         }
 451
 452                         $this->report( 'orphans', $i, $numOrphans );
 453                 }
 454                 $this->report( 'orphans', $i, $numOrphans );
 455                 $this->info( "All orphans queued." );
 456         }
 457
 458         /**
 459          * Main entry point for worker processes
 460          */
 461         function executeChild() {
 462                 $this->debug( 'starting' );
 463                 $this->syncDBs();
 464
 465                 while ( !feof( STDIN ) ) {
 466                         $line = rtrim( fgets( STDIN ) );
 467                         if ( $line == '' ) {
 468                                 continue;
 469                         }
 470                         $this->debug( $line );
 471                         $args = explode( ' ', $line );
 472                         $cmd = array_shift( $args );
 473                         switch ( $cmd ) {
 474                                 case 'doPage':
 475                                         $this->doPage( intval( $args[0] ) );
 476                                         break;
 477                                 case 'doOrphanList':
 478                                         $this->doOrphanList( array_map( 'intval', $args ) );
 479                                         break;
 480                                 case 'quit':
 481                                         return;
 482                         }
 483                         MediaWikiServices::getInstance()->getDBLoadBalancerFactory()->waitForReplication();
 484                 }
 485         }
 486
 487         /**
 488          * Move tracked text in a given page
 489          *
 490          * @param int $pageId
 491          */
 492         function doPage( $pageId ) {
 493                 $title = Title::newFromID( $pageId );
 494                 if ( $title ) {
 495                         $titleText = $title->getPrefixedText();
 496                 } else {
 497                         $titleText = '[deleted]';
 498                 }
 499                 $dbr = wfGetDB( DB_REPLICA );
 500
 501                 // Finish any incomplete transactions
 502                 if ( !$this->copyOnly ) {
 503                         $this->finishIncompleteMoves( [ 'bt_page' => $pageId ] );
 504                         $this->syncDBs();
 505                 }
 506
 507                 $startId = 0;
 508                 $trx = new CgzCopyTransaction( $this, $this->pageBlobClass );
 509
 510                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 511                 while ( true ) {
 512                         $res = $dbr->select(
 513                                 [ 'blob_tracking', 'text' ],
 514                                 '*',
 515                                 [
 516                                         'bt_page' => $pageId,
 517                                         'bt_text_id > ' . $dbr->addQuotes( $startId ),
 518                                         'bt_moved' => 0,
 519                                         'bt_new_url IS NULL',
 520                                         'bt_text_id=old_id',
 521                                 ],
 522                                 __METHOD__,
 523                                 [
 524                                         'ORDER BY' => 'bt_text_id',
 525                                         'LIMIT' => $this->batchSize
 526                                 ]
 527                         );
 528                         if ( !$res->numRows() ) {
 529                                 break;
 530                         }
 531
 532                         $lastTextId = 0;
 533                         foreach ( $res as $row ) {
 534                                 $startId = $row->bt_text_id;
 535                                 if ( $lastTextId == $row->bt_text_id ) {
 536                                         // Duplicate (null edit)
 537                                         continue;
 538                                 }
 539                                 $lastTextId = $row->bt_text_id;
 540                                 // Load the text
 541                                 $text = $this->blobStore->expandBlob( $row->old_text, $row->old_flags );
 542                                 if ( $text === false ) {
 543                                         $this->critical( "Error loading {$row->bt_rev_id}/{$row->bt_text_id}" );
 544                                         continue;
 545                                 }
 546
 547                                 // Queue it
 548                                 if ( !$trx->addItem( $text, $row->bt_text_id ) ) {
 549                                         $this->debug( "$titleText: committing blob with " . $trx->getSize() . " items" );
 550                                         $trx->commit();
 551                                         $trx = new CgzCopyTransaction( $this, $this->pageBlobClass );
 552                                         $lbFactory->waitForReplication();
 553                                 }
 554                         }
 555                 }
 556
 557                 $this->debug( "$titleText: committing blob with " . $trx->getSize() . " items" );
 558                 $trx->commit();
 559         }
 560
 561         /**
 562          * Atomic move operation.
 563          *
 564          * Write the new URL to the text table and set the bt_moved flag.
 565          *
 566          * This is done in a single transaction to provide restartable behavior
 567          * without data loss.
 568          *
 569          * The transaction is kept short to reduce locking.
 570          *
 571          * @param int $textId
 572          * @param string $url
 573          */
 574         function moveTextRow( $textId, $url ) {
 575                 if ( $this->copyOnly ) {
 576                         $this->critical( "Internal error: can't call moveTextRow() in --copy-only mode" );
 577                         exit( 1 );
 578                 }
 579                 $dbw = wfGetDB( DB_MASTER );
 580                 $dbw->begin( __METHOD__ );
 581                 $dbw->update( 'text',
 582                         [ // set
 583                                 'old_text' => $url,
 584                                 'old_flags' => 'external,utf-8',
 585                         ],
 586                         [ // where
 587                                 'old_id' => $textId
 588                         ],
 589                         __METHOD__
 590                 );
 591                 $dbw->update( 'blob_tracking',
 592                         [ 'bt_moved' => 1 ],
 593                         [ 'bt_text_id' => $textId ],
 594                         __METHOD__
 595                 );
 596                 $dbw->commit( __METHOD__ );
 597         }
 598
 599         /**
 600          * Moves are done in two phases: bt_new_url and then bt_moved.
 601          *  - bt_new_url indicates that the text has been copied to the new cluster.
 602          *  - bt_moved indicates that the text table has been updated.
 603          *
 604          * This function completes any moves that only have done bt_new_url. This
 605          * can happen when the script is interrupted, or when --copy-only is used.
 606          *
 607          * @param array $conds
 608          */
 609         function finishIncompleteMoves( $conds ) {
 610                 $dbr = wfGetDB( DB_REPLICA );
 611                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 612
 613                 $startId = 0;
 614                 $conds = array_merge( $conds, [
 615                         'bt_moved' => 0,
 616                         'bt_new_url IS NOT NULL'
 617                 ] );
 618                 while ( true ) {
 619                         $res = $dbr->select( 'blob_tracking',
 620                                 '*',
 621                                 array_merge( $conds, [ 'bt_text_id > ' . $dbr->addQuotes( $startId ) ] ),
 622                                 __METHOD__,
 623                                 [
 624                                         'ORDER BY' => 'bt_text_id',
 625                                         'LIMIT' => $this->batchSize,
 626                                 ]
 627                         );
 628                         if ( !$res->numRows() ) {
 629                                 break;
 630                         }
 631                         $this->debug( 'Incomplete: ' . $res->numRows() . ' rows' );
 632                         foreach ( $res as $row ) {
 633                                 $startId = $row->bt_text_id;
 634                                 $this->moveTextRow( $row->bt_text_id, $row->bt_new_url );
 635                                 if ( $row->bt_text_id % 10 == 0 ) {
 636                                         $lbFactory->waitForReplication();
 637                                 }
 638                         }
 639                 }
 640         }
 641
 642         /**
 643          * Returns the name of the next target cluster
 644          * @return string
 645          */
 646         function getTargetCluster() {
 647                 $cluster = next( $this->destClusters );
 648                 if ( $cluster === false ) {
 649                         $cluster = reset( $this->destClusters );
 650                 }
 651
 652                 return $cluster;
 653         }
 654
 655         /**
 656          * Gets a DB master connection for the given external cluster name
 657          * @param string $cluster
 658          * @return IMaintainableDatabase
 659          */
 660         function getExtDB( $cluster ) {
 661                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 662                 $lb = $lbFactory->getExternalLB( $cluster );
 663
 664                 return $lb->getMaintenanceConnectionRef( DB_MASTER );
 665         }
 666
 667         /**
 668          * Move an orphan text_id to the new cluster
 669          *
 670          * @param array $textIds
 671          */
 672         function doOrphanList( $textIds ) {
 673                 // Finish incomplete moves
 674                 if ( !$this->copyOnly ) {
 675                         $this->finishIncompleteMoves( [ 'bt_text_id' => $textIds ] );
 676                         $this->syncDBs();
 677                 }
 678
 679                 $trx = new CgzCopyTransaction( $this, $this->orphanBlobClass );
 680
 681                 $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
 682                 $res = wfGetDB( DB_REPLICA )->select(
 683                         [ 'text', 'blob_tracking' ],
 684                         [ 'old_id', 'old_text', 'old_flags' ],
 685                         [
 686                                 'old_id' => $textIds,
 687                                 'bt_text_id=old_id',
 688                                 'bt_moved' => 0,
 689                         ],
 690                         __METHOD__,
 691                         [ 'DISTINCT' ]
 692                 );
 693
 694                 foreach ( $res as $row ) {
 695                         $text = $this->blobStore->expandBlob( $row->old_text, $row->old_flags );
 696                         if ( $text === false ) {
 697                                 $this->critical( "Error: cannot load revision text for old_id={$row->old_id}" );
 698                                 continue;
 699                         }
 700
 701                         if ( !$trx->addItem( $text, $row->old_id ) ) {
 702                                 $this->debug( "[orphan]: committing blob with " . $trx->getSize() . " rows" );
 703                                 $trx->commit();
 704                                 $trx = new CgzCopyTransaction( $this, $this->orphanBlobClass );
 705                                 $lbFactory->waitForReplication();
 706                         }
 707                 }
 708                 $this->debug( "[orphan]: committing blob with " . $trx->getSize() . " rows" );
 709                 $trx->commit();
 710         }
 711 }
 712
 713 /**
 714  * Class to represent a recompression operation for a single CGZ blob
 715  */
 716 class CgzCopyTransaction {
 717         /** @var RecompressTracked */
 718         public $parent;
 719         public $blobClass;
 720         /** @var ConcatenatedGzipHistoryBlob|false */
 721         public $cgz;
 722         public $referrers;
 723         /** @var array */
 724         private $texts;
 725
 726         /**
 727          * Create a transaction from a RecompressTracked object
 728          * @param RecompressTracked $parent
 729          * @param string $blobClass
 730          */
 731         function __construct( $parent, $blobClass ) {
 732                 $this->blobClass = $blobClass;
 733                 $this->cgz = false;
 734                 $this->texts = [];
 735                 $this->parent = $parent;
 736         }
 737
 738         /**
 739          * Add text.
 740          * Returns false if it's ready to commit.
 741          * @param string $text
 742          * @param int $textId
 743          * @return bool
 744          */
 745         function addItem( $text, $textId ) {
 746                 if ( !$this->cgz ) {
 747                         $class = $this->blobClass;
 748                         $this->cgz = new $class;
 749                 }
 750                 $hash = $this->cgz->addItem( $text );
 751                 $this->referrers[$textId] = $hash;
 752                 $this->texts[$textId] = $text;
 753
 754                 return $this->cgz->isHappy();
 755         }
 756
 757         function getSize() {
 758                 return count( $this->texts );
 759         }
 760
 761         /**
 762          * Recompress text after some aberrant modification
 763          */
 764         function recompress() {
 765                 $class = $this->blobClass;
 766                 $this->cgz = new $class;
 767                 $this->referrers = [];
 768                 foreach ( $this->texts as $textId => $text ) {
 769                         $hash = $this->cgz->addItem( $text );
 770                         $this->referrers[$textId] = $hash;
 771                 }
 772         }
 773
 774         /**
 775          * Commit the blob.
 776          * Does nothing if no text items have been added.
 777          * May skip the move if --copy-only is set.
 778          */
 779         function commit() {
 780                 $originalCount = count( $this->texts );
 781                 if ( !$originalCount ) {
 782                         return;
 783                 }
 784
 785                 /* Check to see if the target text_ids have been moved already.
 786                  *
 787                  * We originally read from the replica DB, so this can happen when a single
 788                  * text_id is shared between multiple pages. It's rare, but possible
 789                  * if a delete/move/undelete cycle splits up a null edit.
 790                  *
 791                  * We do a locking read to prevent closer-run race conditions.
 792                  */
 793                 $dbw = wfGetDB( DB_MASTER );
 794                 $dbw->begin( __METHOD__ );
 795                 $res = $dbw->select( 'blob_tracking',
 796                         [ 'bt_text_id', 'bt_moved' ],
 797                         [ 'bt_text_id' => array_keys( $this->referrers ) ],
 798                         __METHOD__, [ 'FOR UPDATE' ] );
 799                 $dirty = false;
 800                 foreach ( $res as $row ) {
 801                         if ( $row->bt_moved ) {
 802                                 # This row has already been moved, remove it
 803                                 $this->parent->debug( "TRX: conflict detected in old_id={$row->bt_text_id}" );
 804                                 unset( $this->texts[$row->bt_text_id] );
 805                                 $dirty = true;
 806                         }
 807                 }
 808
 809                 // Recompress the blob if necessary
 810                 if ( $dirty ) {
 811                         if ( !count( $this->texts ) ) {
 812                                 // All have been moved already
 813                                 if ( $originalCount > 1 ) {
 814                                         // This is suspcious, make noise
 815                                         $this->parent->critical(
 816                                                 "Warning: concurrent operation detected, are there two conflicting " .
 817                                                 "processes running, doing the same job?" );
 818                                 }
 819
 820                                 return;
 821                         }
 822                         $this->recompress();
 823                 }
 824
 825                 // Insert the data into the destination cluster
 826                 $targetCluster = $this->parent->getTargetCluster();
 827                 $store = $this->parent->store;
 828                 $targetDB = $store->getMaster( $targetCluster );
 829                 $targetDB->clearFlag( DBO_TRX ); // we manage the transactions
 830                 $targetDB->begin( __METHOD__ );
 831                 $baseUrl = $this->parent->store->store( $targetCluster, serialize( $this->cgz ) );
 832
 833                 // Write the new URLs to the blob_tracking table
 834                 foreach ( $this->referrers as $textId => $hash ) {
 835                         $url = $baseUrl . '/' . $hash;
 836                         $dbw->update( 'blob_tracking',
 837                                 [ 'bt_new_url' => $url ],
 838                                 [
 839                                         'bt_text_id' => $textId,
 840                                         'bt_moved' => 0, # Check for concurrent conflicting update
 841                                 ],
 842                                 __METHOD__
 843                         );
 844                 }
 845
 846                 $targetDB->commit( __METHOD__ );
 847                 // Critical section here: interruption at this point causes blob duplication
 848                 // Reversing the order of the commits would cause data loss instead
 849                 $dbw->commit( __METHOD__ );
 850
 851                 // Write the new URLs to the text table and set the moved flag
 852                 if ( !$this->parent->copyOnly ) {
 853                         foreach ( $this->referrers as $textId => $hash ) {
 854                                 $url = $baseUrl . '/' . $hash;
 855                                 $this->parent->moveTextRow( $textId, $url );
 856                         }
 857                 }
 858         }
 859 }