maintenance/storage/recompressTracked.php

   1 <?php
   2
   3 $optionsWithArgs = RecompressTracked::getOptionsWithArgs();
   4 require( dirname( __FILE__ ) .'/../commandLine.inc' );
   5
   6 if ( count( $args ) < 1 ) {
   7         echo "Usage: php recompressTracked.php [options] <cluster> [... <cluster>...]
   8 Moves blobs indexed by trackBlobs.php to a specified list of destination clusters, and recompresses them in the process. Restartable.
   9
  10 Options:
  11     --procs <procs>     Set the number of child processes (default 8)
  12     --copy-only         Copy only, do not update the text table. Restart without this option to complete.
  13 ";
  14         exit( 1 );
  15 }
  16
  17 $job = RecompressTracked::newFromCommandLine( $args, $options );
  18 $job->execute();
  19
  20 class RecompressTracked {
  21         var $destClusters;
  22         var $batchSize = 1000;
  23         var $reportingInterval = 10;
  24         var $numProcs = 8;
  25         var $useDiff, $pageBlobClass, $orphanBlobClass;
  26         var $slavePipes, $slaveProcs, $prevSlaveId;
  27         var $copyOnly = false;
  28         var $isChild = false;
  29         var $slaveId = false;
  30         var $store;
  31
  32         static $optionsWithArgs = array( 'procs', 'slave-id' );
  33         static $cmdLineOptionMap = array(
  34                 'procs' => 'numProcs',
  35                 'copy-only' => 'copyOnly',
  36                 'child' => 'isChild',
  37                 'slave-id' => 'slaveId',
  38         );
  39
  40         static function getOptionsWithArgs() {
  41                 return self::$optionsWithArgs;
  42         }
  43
  44         static function newFromCommandLine( $args, $options ) {
  45                 $jobOptions = array( 'destClusters' => $args );
  46                 foreach ( self::$cmdLineOptionMap as $cmdOption => $classOption ) {
  47                         if ( isset( $options[$cmdOption] ) ) {
  48                                 $jobOptions[$classOption] = $options[$cmdOption];
  49                         }
  50                 }
  51                 return new self( $jobOptions );
  52         }
  53
  54         function __construct( $options ) {
  55                 foreach ( $options as $name => $value ) {
  56                         $this->$name = $value;
  57                 }
  58                 $this->store = new ExternalStoreDB;
  59                 if ( !$this->isChild ) {
  60                         $GLOBALS['wgDebugLogPrefix'] = "RCT M: ";
  61                 } elseif ( $this->slaveId !== false ) {
  62                         $GLOBALS['wgDebugLogPrefix'] = "RCT {$this->slaveId}: ";
  63                 }
  64                 $this->useDiff = function_exists( 'xdiff_string_bdiff' );
  65                 $this->pageBlobClass = $this->useDiff ? 'DiffHistoryBlob' : 'ConcatenatedGzipHistoryBlob';
  66                 $this->orphanBlobClass = 'ConcatenatedGzipHistoryBlob';
  67         }
  68
  69         function debug( $msg ) {
  70                 wfDebug( "$msg\n" );
  71         }
  72
  73         /**
  74          * Wait until the selected slave has caught up to the master.
  75          * This allows us to use the slave for things that were committed in a
  76          * previous part of this batch process.
  77          */
  78         function syncDBs() {
  79                 $dbw = wfGetDB( DB_MASTER );
  80                 $dbr = wfGetDB( DB_SLAVE );
  81                 $pos = $dbw->getMasterPos();
  82                 $dbr->masterPosWait( $pos, 100000 );
  83         }
  84
  85         /**
  86          * Execute parent or child depending on the isChild option
  87          */
  88         function execute() {
  89                 if ( $this->isChild ) {
  90                         $this->executeChild();
  91                 } else {
  92                         $this->executeParent();
  93                 }
  94         }
  95
  96         /**
  97          * Execute the parent process
  98          */
  99         function executeParent() {
 100                 if ( !$this->checkTrackingTable() ) {
 101                         return;
 102                 }
 103
 104                 $this->syncDBs();
 105                 $this->startSlaveProcs();
 106                 $this->doAllPages();
 107                 $this->doAllOrphans();
 108                 $this->killSlaveProcs();
 109         }
 110
 111         /**
 112          * Make sure the tracking table exists and isn't empty
 113          */
 114         function checkTrackingTable() {
 115                 $dbr = wfGetDB( DB_SLAVE );
 116                 if ( !$dbr->tableExists( 'blob_tracking' ) ) {
 117                         echo "Error: blob_tracking table does not exist\n";
 118                         return false;
 119                 }
 120                 $row = $dbr->selectRow( 'blob_tracking', '*', false, __METHOD__ );
 121                 if ( !$row ) {
 122                         echo "Warning: blob_tracking table contains no rows, skipping this wiki.\n";
 123                         return false;
 124                 }
 125                 return true;
 126         }
 127
 128         /**
 129          * Start the worker processes.
 130          * These processes will listen on stdin for commands.
 131          * This necessary because text recompression is slow: loading, compressing and
 132          * writing are all slow.
 133          */
 134         function startSlaveProcs() {
 135                 $cmd = 'php ' . wfEscapeShellArg( __FILE__ );
 136                 foreach ( self::$cmdLineOptionMap as $cmdOption => $classOption ) {
 137                         if ( in_array( $cmdOption, self::$optionsWithArgs ) ) {
 138                                 $cmd .= " --$cmdOption " . wfEscapeShellArg( $this->$classOption );
 139                         } elseif ( $this->$classOption ) {
 140                                 $cmd .= " --$cmdOption";
 141                         }
 142                 }
 143                 $cmd .= ' --child' .
 144                         ' --wiki ' . wfEscapeShellArg( wfWikiID() ) .
 145                         ' ' . call_user_func_array( 'wfEscapeShellArg', $this->destClusters );
 146
 147                 $this->slavePipes = $this->slaveProcs = array();
 148                 for ( $i = 0; $i < $this->numProcs; $i++ ) {
 149                         $pipes = false;
 150                         $spec = array(
 151                                 array( 'pipe', 'r' ),
 152                                 array( 'file', '/dev/stdout', 'w' ),
 153                                 array( 'file', '/dev/stderr', 'w' )
 154                         );
 155                         wfSuppressWarnings();
 156                         $proc = proc_open( "$cmd --slave-id $i", $spec, $pipes );
 157                         wfRestoreWarnings();
 158                         if ( !$proc ) {
 159                                 echo "Error opening slave process\n";
 160                                 exit( 1 );
 161                         }
 162                         $this->slaveProcs[$i] = $proc;
 163                         $this->slavePipes[$i] = $pipes[0];
 164                 }
 165                 $this->prevSlaveId = -1;
 166         }
 167
 168         /**
 169          * Gracefully terminate the child processes
 170          */
 171         function killSlaveProcs() {
 172                 for ( $i = 0; $i < $this->numProcs; $i++ ) {
 173                         $this->dispatchToSlave( $i, 'quit' );
 174                 }
 175                 for ( $i = 0; $i < $this->numProcs; $i++ ) {
 176                         proc_close( $this->slaveProcs[$i] );
 177                 }
 178         }
 179
 180         /**
 181          * Dispatch a command to the next available slave.
 182          * This may block until a slave finishes its work and becomes available.
 183          */
 184         function dispatch( /*...*/ ) {
 185                 $args = func_get_args();
 186                 $pipes = $this->slavePipes;
 187                 $numPipes = stream_select( $x=array(), $pipes, $y=array(), 3600 );
 188                 if ( !$numPipes ) {
 189                         echo "Error waiting to write to slaves. Aborting\n";
 190                         exit( 1 );
 191                 }
 192                 for ( $i = 0; $i < $this->numProcs; $i++ ) {
 193                         $slaveId = ( $i + $this->prevSlaveId + 1 ) % $this->numProcs;
 194                         if ( isset( $pipes[$slaveId] ) ) {
 195                                 $this->prevSlaveId = $slaveId;
 196                                 $this->dispatchToSlave( $slaveId, $args );
 197                                 return;
 198                         }
 199                 }
 200                 echo "Unreachable\n";
 201                 exit( 1 );
 202         }
 203
 204         /**
 205          * Dispatch a command to a specified slave
 206          */
 207         function dispatchToSlave( $slaveId, $args ) {
 208                 $args = (array)$args;
 209                 $cmd = implode( ' ',  $args );
 210                 fwrite( $this->slavePipes[$slaveId], "$cmd\n" );
 211         }
 212
 213         /**
 214          * Move all tracked pages to the new clusters
 215          */
 216         function doAllPages() {
 217                 $dbr = wfGetDB( DB_SLAVE );
 218                 $startId = 0;
 219                 $endId = $dbr->selectField( 'blob_tracking', 'MAX(bt_page)',
 220                         # A condition is required so that this query uses the index
 221                         array( 'bt_moved' => 0 ),
 222                         __METHOD__ );
 223                 echo "Moving pages...\n";
 224                 while ( true ) {
 225                         $res = $dbr->select( 'blob_tracking',
 226                                 array( 'bt_page' ),
 227                                 array(
 228                                         'bt_moved' => 0,
 229                                         'bt_page > ' . $dbr->addQuotes( $startId )
 230                                 ),
 231                                 __METHOD__,
 232                                 array(
 233                                         'DISTINCT',
 234                                         'ORDER BY' => 'bt_page',
 235                                         'LIMIT' => $this->batchSize,
 236                                 )
 237                         );
 238                         if ( !$res->numRows() ) {
 239                                 break;
 240                         }
 241                         foreach ( $res as $row ) {
 242                                 $this->dispatch( 'doPage', $row->bt_page );
 243                         }
 244                         $startId = $row->bt_page;
 245                         $this->report( $startId, $endId );
 246                 }
 247                 echo "Done moving pages.\n";
 248         }
 249
 250         /**
 251          * Display a progress report
 252          */
 253         function report( $start, $end ) {
 254                 $this->numBatches++;
 255                 if ( $this->numBatches >= $this->reportingInterval ) {
 256                         $this->numBatches = 0;
 257                         echo "$start / $end\n";
 258                         wfWaitForSlaves( 5 );
 259                 }
 260         }
 261
 262         /**
 263          * Move all orphan text to the new clusters
 264          */
 265         function doAllOrphans() {
 266                 $dbr = wfGetDB( DB_SLAVE );
 267                 $startId = 0;
 268                 $endId = $dbr->selectField( 'blob_tracking', 'MAX(bt_text_id)',
 269                         array( 'bt_moved' => 0, 'bt_page' => 0 ),
 270                         __METHOD__ );
 271                 if ( !$endId ) {
 272                         return;
 273                 }
 274                 echo "Moving orphans...\n";
 275
 276                 while ( true ) {
 277                         $res = $dbr->select( 'blob_tracking',
 278                                 array( 'bt_text_id' ),
 279                                 array(
 280                                         'bt_moved' => 0,
 281                                         'bt_page' => 0,
 282                                         'bt_text_id > ' . $dbr->addQuotes( $startId )
 283                                 ),
 284                                 __METHOD__,
 285                                 array(
 286                                         'DISTINCT',
 287                                         'ORDER BY' => 'bt_text_id',
 288                                         'LIMIT' => $this->batchSize
 289                                 )
 290                         );
 291                         if ( !$res->numRows() ) {
 292                                 break;
 293                         }
 294                         $args = array( 'doOrphanList' );
 295                         foreach ( $res as $row ) {
 296                                 $args[] = $row->bt_text_id;
 297                         }
 298                         call_user_func_array( array( $this, 'dispatch' ), $args );
 299                         $startId = $row->bt_text_id;
 300                         $this->report( $startId, $endId );
 301                 }
 302                 echo "Done moving orphans.\n";
 303         }
 304
 305         /**
 306          * Main entry point for worker processes
 307          */
 308         function executeChild() {
 309                 $this->debug( 'starting' );
 310                 $this->syncDBs();
 311
 312                 while ( !feof( STDIN ) ) {
 313                         $line = rtrim( fgets( STDIN ) );
 314                         if ( $line == '' ) {
 315                                 continue;
 316                         }
 317                         $this->debug( $line );
 318                         $args = explode( ' ', $line );
 319                         $cmd = array_shift( $args );
 320                         switch ( $cmd ) {
 321                         case 'doPage':
 322                                 $this->doPage( intval( $args[0] ) );
 323                                 break;
 324                         case 'doOrphanList':
 325                                 $this->doOrphanList( array_map( 'intval', $args ) );
 326                                 break;
 327                         case 'quit':
 328                                 return;
 329                         }
 330                 }
 331         }
 332
 333         /**
 334          * Move tracked text in a given page
 335          */
 336         function doPage( $pageId ) {
 337                 $title = Title::newFromId( $pageId );
 338                 if ( $title ) {
 339                         $titleText = $title->getPrefixedText();
 340                 } else {
 341                         $titleText = '[deleted]';
 342                 }
 343                 $dbr = wfGetDB( DB_SLAVE );
 344
 345                 // Finish any incomplete transactions
 346                 if ( !$this->copyOnly ) {
 347                         $this->finishIncompleteMoves( array( 'bt_page' => $pageId ) );
 348                 }
 349
 350                 $startId = 0;
 351                 $trx = new CgzCopyTransaction( $this, $this->pageBlobClass );
 352
 353                 while ( true ) {
 354                         $res = $dbr->select(
 355                                 array( 'blob_tracking', 'text' ),
 356                                 '*',
 357                                 array(
 358                                         'bt_page' => $pageId,
 359                                         'bt_text_id > ' . $dbr->addQuotes( $startId ),
 360                                         'bt_moved' => 0,
 361                                         'bt_new_url IS NULL',
 362                                         'bt_text_id=old_id',
 363                                 ),
 364                                 __METHOD__,
 365                                 array(
 366                                         'ORDER BY' => 'bt_text_id',
 367                                         'LIMIT' => $this->batchSize
 368                                 )
 369                         );
 370                         if ( !$res->numRows() ) {
 371                                 break;
 372                         }
 373
 374                         $lastTextId = 0;
 375                         foreach ( $res as $row ) {
 376                                 if ( $lastTextId == $row->bt_text_id ) {
 377                                         // Duplicate (null edit)
 378                                         continue;
 379                                 }
 380                                 $lastTextId = $row->bt_text_id;
 381                                 // Load the text
 382                                 $text = Revision::getRevisionText( $row );
 383                                 if ( $text === false ) {
 384                                         echo "Error loading {$row->bt_rev_id}/{$row->bt_text_id}\n";
 385                                         continue;
 386                                 }
 387
 388                                 // Queue it
 389                                 if ( !$trx->addItem( $text, $row->bt_text_id ) ) {
 390                                         $this->debug( "$titleText: committing blob with " . $trx->getSize() . " items" );
 391                                         $trx->commit();
 392                                         $trx = new CgzCopyTransaction( $this, $this->pageBlobClass );
 393                                 }
 394                         }
 395                         $startId = $row->bt_text_id;
 396                 }
 397
 398                 $this->debug( "$titleText: committing blob with " . $trx->getSize() . " items" );
 399                 $trx->commit();
 400         }
 401
 402         /**
 403          * Atomic move operation.
 404          *
 405          * Write the new URL to the text table and set the bt_moved flag.
 406          *
 407          * This is done in a single transaction to provide restartable behaviour
 408          * without data loss.
 409          *
 410          * The transaction is kept short to reduce locking.
 411          */
 412         function moveTextRow( $textId, $url ) {
 413                 $dbw = wfGetDB( DB_MASTER );
 414                 $dbw->begin();
 415                 $dbw->update( 'text',
 416                         array( // set
 417                                 'old_text' => $url,
 418                                 'old_flags' => 'external,utf8',
 419                         ),
 420                         array( // where
 421                                 'old_id' => $textId
 422                         ),
 423                         __METHOD__
 424                 );
 425                 $dbw->update( 'blob_tracking',
 426                         array( 'bt_moved' => 1 ),
 427                         array( 'bt_text_id' => $textId ),
 428                         __METHOD__
 429                 );
 430                 $dbw->commit();
 431         }
 432
 433         /**
 434          * Moves are done in two phases: bt_new_url and then bt_moved.
 435          *  - bt_new_url indicates that the text has been copied to the new cluster.
 436          *  - bt_moved indicates that the text table has been updated.
 437          *
 438          * This function completes any moves that only have done bt_new_url. This
 439          * can happen when the script is interrupted, or when --copy-only is used.
 440          */
 441         function finishIncompleteMoves( $conds ) {
 442                 $dbr = wfGetDB( DB_SLAVE );
 443
 444                 $startId = 0;
 445                 $conds = array_merge( $conds, array(
 446                         'bt_moved' => 0,
 447                         'bt_new_url IS NOT NULL'
 448                 ));
 449                 while ( true ) {
 450                         $res = $dbr->select( 'blob_tracking',
 451                                 '*',
 452                                 array_merge( $conds, array( 'bt_text_id > ' . $dbr->addQuotes( $startId ) ) ),
 453                                 __METHOD__,
 454                                 array(
 455                                         'ORDER BY' => 'bt_text_id',
 456                                         'LIMIT' => $this->batchSize,
 457                                 )
 458                         );
 459                         if ( !$res->numRows() ) {
 460                                 break;
 461                         }
 462                         $this->debug( 'Incomplete: ' . $res->numRows() . ' rows' );
 463                         foreach ( $res as $row ) {
 464                                 $this->moveTextRow( $row->bt_text_id, $row->bt_new_url );
 465                         }
 466                         $startId = $row->bt_text_id;
 467                 }
 468         }
 469
 470         /**
 471          * Returns the name of the next target cluster
 472          */
 473         function getTargetCluster() {
 474                 $cluster = next( $this->destClusters );
 475                 if ( $cluster === false ) {
 476                         $cluster = reset( $this->destClusters );
 477                 }
 478                 return $cluster;
 479         }
 480
 481         /**
 482          * Gets a DB master connection for the given external cluster name
 483          */
 484         function getExtDB( $cluster ) {
 485                 $lb = wfGetLBFactory()->getExternalLB( $cluster );
 486                 return $lb->getConnection( DB_MASTER );
 487         }
 488
 489         /**
 490          * Move an orphan text_id to the new cluster
 491          */
 492         function doOrphanList( $textIds ) {
 493                 // Finish incomplete moves
 494                 $this->finishIncompleteMoves( array( 'bt_text_id' => $textIds ) );
 495
 496                 $trx = new CgzCopyTransaction( $this, $this->orphanBlobClass );
 497                 foreach ( $textIds as $textId ) {
 498                         $row = wfGetDB( DB_SLAVE )->selectRow( 'text', array( 'old_text', 'old_flags' ),
 499                                 array( 'old_id' => $textId ), __METHOD__ );
 500                         $text = Revision::getRevisionText( $row );
 501                         if ( $text === false ) {
 502                                 echo "Error: cannot load revision text for $textId\n";
 503                                 continue;
 504                         }
 505
 506                         if ( !$trx->addItem( $text, $textId ) ) {
 507                                 $this->debug( "[orphan]: committing blob with " . $trx->getSize() . " rows" );
 508                                 $trx->commit();
 509                                 $trx = new CgzCopyTransaction( $this, $this->orphanBlobClass );
 510                         }
 511                 }
 512                 $this->debug( "[orphan]: committing blob with " . $trx->getSize() . " rows" );
 513                 $trx->commit();
 514         }
 515 }
 516
 517 /**
 518  * Class to represent a recompression operation for a single CGZ blob
 519  */
 520 class CgzCopyTransaction {
 521         var $parent;
 522         var $blobClass;
 523         var $cgz;
 524         var $referrers;
 525
 526         /**
 527          * Create a transaction from a RecompressTracked object
 528          */
 529         function __construct( $parent, $blobClass ) {
 530                 $this->blobClass = $blobClass;
 531                 $this->cgz = false;
 532                 $this->texts = array();
 533                 $this->parent = $parent;
 534         }
 535
 536         /**
 537          * Add text.
 538          * Returns false if it's ready to commit.
 539          */
 540         function addItem( $text, $textId ) {
 541                 if ( !$this->cgz ) {
 542                         $class = $this->blobClass;
 543                         $this->cgz = new $class;
 544                 }
 545                 $hash = $this->cgz->addItem( $text );
 546                 $this->referrers[$textId] = $hash;
 547                 $this->texts[$textId] = $text;
 548                 return $this->cgz->isHappy();
 549         }
 550
 551         function getSize() {
 552                 return count( $this->texts );
 553         }
 554
 555         /**
 556          * Recompress text after some aberrant modification
 557          */
 558         function recompress() {
 559                 $class = $this->blobClass;
 560                 $this->cgz = new $class;
 561                 $this->referrers = array();
 562                 foreach ( $this->texts as $textId => $text ) {
 563                         $hash = $this->cgz->addItem( $text );
 564                         $this->referrers[$textId] = $hash;
 565                 }
 566         }
 567
 568         /**
 569          * Commit the blob.
 570          * Does nothing if no text items have been added.
 571          * May skip the move if --copy-only is set.
 572          */
 573         function commit() {
 574                 $originalCount = count( $this->texts );
 575                 if ( !$originalCount ) {
 576                         return;
 577                 }
 578
 579                 // Check to see if the target text_ids have been moved already.
 580                 //
 581                 // We originally read from the slave, so this can happen when a single
 582                 // text_id is shared between multiple pages. It's rare, but possible
 583                 // if a delete/move/undelete cycle splits up a null edit.
 584                 //
 585                 // We do a locking read to prevent closer-run race conditions.
 586                 $dbw = wfGetDB( DB_MASTER );
 587                 $dbw->begin();
 588                 $res = $dbw->select( 'blob_tracking',
 589                         array( 'bt_text_id', 'bt_moved' ),
 590                         array( 'bt_text_id' => array_keys( $this->referrers ) ),
 591                         __METHOD__, array( 'FOR UPDATE' ) );
 592                 $dirty = false;
 593                 foreach ( $res as $row ) {
 594                         if ( $row->bt_moved ) {
 595                                 # This row has already been moved, remove it
 596                                 $this->parent->debug( "TRX: conflict detected in old_id={$row->bt_text_id}" );
 597                                 unset( $this->texts[$row->bt_text_id] );
 598                                 $dirty = true;
 599                         }
 600                 }
 601
 602                 // Recompress the blob if necessary
 603                 if ( $dirty ) {
 604                         if ( !count( $this->texts ) ) {
 605                                 // All have been moved already
 606                                 if ( $originalCount > 1 ) {
 607                                         // This is suspcious, make noise
 608                                         echo "Warning: concurrent operation detected, are there two conflicting " .
 609                                                 "processes running, doing the same job?\n";
 610                                 }
 611                                 return;
 612                         }
 613                         $this->recompress();
 614                 }
 615
 616                 // Insert the data into the destination cluster
 617                 $targetCluster = $this->parent->getTargetCluster();
 618                 $store = $this->parent->store;
 619                 $targetDB = $store->getMaster( $targetCluster );
 620                 $targetDB->clearFlag( DBO_TRX ); // we manage the transactions
 621                 $targetDB->begin();
 622                 $baseUrl = $this->parent->store->store( $targetCluster, serialize( $this->cgz ) );
 623
 624                 // Write the new URLs to the blob_tracking table
 625                 foreach ( $this->referrers as $textId => $hash ) {
 626                         $url = $baseUrl . '/' . $hash;
 627                         $dbw->update( 'blob_tracking',
 628                                 array( 'bt_new_url' => $url ),
 629                                 array(
 630                                         'bt_text_id' => $textId,
 631                                         'bt_moved' => 0, # Check for concurrent conflicting update
 632                                 ),
 633                                 __METHOD__
 634                         );
 635                 }
 636
 637                 $targetDB->commit();
 638                 // Critical section here: interruption at this point causes blob duplication
 639                 // Reversing the order of the commits would cause data loss instead
 640                 $dbw->commit();
 641
 642                 // Write the new URLs to the text table and set the moved flag
 643                 if ( !$this->parent->copyOnly ) {
 644                         foreach ( $this->referrers as $textId => $hash ) {
 645                                 $url = $baseUrl . '/' . $hash;
 646                                 $this->parent->moveTextRow( $textId, $url );
 647                         }
 648                 }
 649         }
 650 }
 651