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 25use MediaWiki\Logger\LegacyLogger; 26use MediaWiki\MediaWikiServices; 27use MediaWiki\Shell\Shell; 28use MediaWiki\Storage\SqlBlobStore; 29use Wikimedia\Rdbms\IMaintainableDatabase; 30 31$optionsWithArgs = RecompressTracked::getOptionsWithArgs(); 32require __DIR__ . '/../commandLine.inc'; 33 34if ( count( $args ) < 1 ) { 35 echo "Usage: php recompressTracked.php [options] <cluster> [... <cluster>...] 36Moves blobs indexed by trackBlobs.php to a specified list of destination clusters, 37and recompresses them in the process. Restartable. 38 39Options: 40 --procs <procs> Set the number of child processes (default 1) 41 --copy-only Copy only, do not update the text table. Restart 42 without this option to complete. 43 --debug-log <file> Log debugging data to the specified file 44 --info-log <file> Log progress messages to the specified file 45 --critical-log <file> Log error messages to the specified file 46"; 47 exit( 1 ); 48} 49 50$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 */ 59class 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 $cmdLineOptionMap = [ 87 'no-count' => 'noCount', 88 'procs' => 'numProcs', 89 'copy-only' => 'copyOnly', 90 'child' => 'isChild', 91 'child-id' => 'childId', 92 'debug-log' => 'debugLog', 93 'info-log' => 'infoLog', 94 'critical-log' => 'criticalLog', 95 ]; 96 97 public static function getOptionsWithArgs() { 98 return self::$optionsWithArgs; 99 } 100 101 public 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 public 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; 126 127 $this->blobStore = MediaWikiServices::getInstance() 128 ->getBlobStoreFactory() 129 ->newSqlBlobStore(); 130 } 131 132 public function debug( $msg ) { 133 wfDebug( "$msg" ); 134 if ( $this->debugLog ) { 135 $this->logToFile( $msg, $this->debugLog ); 136 } 137 } 138 139 public function info( $msg ) { 140 echo "$msg\n"; 141 if ( $this->infoLog ) { 142 $this->logToFile( $msg, $this->infoLog ); 143 } 144 } 145 146 public function critical( $msg ) { 147 echo "$msg\n"; 148 if ( $this->criticalLog ) { 149 $this->logToFile( $msg, $this->criticalLog ); 150 } 151 } 152 153 private 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 private 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 public function execute() { 178 if ( $this->isChild ) { 179 $this->executeChild(); 180 } else { 181 $this->executeParent(); 182 } 183 } 184 185 /** 186 * Execute the parent process 187 */ 188 public function executeParent() { 189 if ( !$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 private function checkTrackingTable() { 205 $dbr = wfGetDB( DB_REPLICA ); 206 if ( !$dbr->tableExists( 'blob_tracking', __METHOD__ ) ) { 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 private function startChildProcs() { 228 $wiki = WikiMap::getCurrentWikiId(); 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 private 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 private 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 private 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 private 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 private 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 private 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 public 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 private 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 public 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 private 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 public 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 private 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 private 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 */ 716class 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 public 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 public 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 public function getSize() { 758 return count( $this->texts ); 759 } 760 761 /** 762 * Recompress text after some aberrant modification 763 */ 764 public 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 public 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} 860