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