includes/WatchedItemStore.php

   1 <?php
   2
   3 use Wikimedia\Assert\Assert;
   4
   5 /**
   6  * Storage layer class for WatchedItems.
   7  * Database interaction.
   8  *
   9  * @author Addshore
  10  *
  11  * @since 1.27
  12  */
  13 class WatchedItemStore {
  14
  15         /**
  16          * @var LoadBalancer
  17          */
  18         private $loadBalancer;
  19
  20         /**
  21          * @var HashBagOStuff
  22          */
  23         private $cache;
  24
  25         /**
  26          * @var array[] Looks like $cacheIndex[Namespace ID][Target DB Key][User Id] => 'key'
  27          * The index is needed so that on mass changes all relevant items can be un-cached.
  28          * For example: Clearing a users watchlist of all items or updating notification timestamps
  29          *              for all users watching a single target.
  30          */
  31         private $cacheIndex = [];
  32
  33         /**
  34          * @var callable|null
  35          */
  36         private $deferredUpdatesAddCallableUpdateCallback;
  37
  38         /**
  39          * @var callable|null
  40          */
  41         private $revisionGetTimestampFromIdCallback;
  42
  43         /**
  44          * @var self|null
  45          */
  46         private static $instance;
  47
  48         /**
  49          * @param LoadBalancer $loadBalancer
  50          * @param HashBagOStuff $cache
  51          */
  52         public function __construct(
  53                 LoadBalancer $loadBalancer,
  54                 HashBagOStuff $cache
  55         ) {
  56                 $this->loadBalancer = $loadBalancer;
  57                 $this->cache = $cache;
  58                 $this->deferredUpdatesAddCallableUpdateCallback = [ 'DeferredUpdates', 'addCallableUpdate' ];
  59                 $this->revisionGetTimestampFromIdCallback = [ 'Revision', 'getTimestampFromId' ];
  60         }
  61
  62         /**
  63          * Overrides the DeferredUpdates::addCallableUpdate callback
  64          * This is intended for use while testing and will fail if MW_PHPUNIT_TEST is not defined.
  65          *
  66          * @param callable $callback
  67          *
  68          * @see DeferredUpdates::addCallableUpdate for callback signiture
  69          *
  70          * @return ScopedCallback to reset the overridden value
  71          * @throws MWException
  72          */
  73         public function overrideDeferredUpdatesAddCallableUpdateCallback( $callback ) {
  74                 if ( !defined( 'MW_PHPUNIT_TEST' ) ) {
  75                         throw new MWException(
  76                                 'Cannot override DeferredUpdates::addCallableUpdate callback in operation.'
  77                         );
  78                 }
  79                 Assert::parameterType( 'callable', $callback, '$callback' );
  80
  81                 $previousValue = $this->deferredUpdatesAddCallableUpdateCallback;
  82                 $this->deferredUpdatesAddCallableUpdateCallback = $callback;
  83                 return new ScopedCallback( function() use ( $previousValue ) {
  84                         $this->deferredUpdatesAddCallableUpdateCallback = $previousValue;
  85                 } );
  86         }
  87
  88         /**
  89          * Overrides the Revision::getTimestampFromId callback
  90          * This is intended for use while testing and will fail if MW_PHPUNIT_TEST is not defined.
  91          *
  92          * @param callable $callback
  93          * @see Revision::getTimestampFromId for callback signiture
  94          *
  95          * @return ScopedCallback to reset the overridden value
  96          * @throws MWException
  97          */
  98         public function overrideRevisionGetTimestampFromIdCallback( $callback ) {
  99                 if ( !defined( 'MW_PHPUNIT_TEST' ) ) {
 100                         throw new MWException(
 101                                 'Cannot override Revision::getTimestampFromId callback in operation.'
 102                         );
 103                 }
 104                 Assert::parameterType( 'callable', $callback, '$callback' );
 105
 106                 $previousValue = $this->revisionGetTimestampFromIdCallback;
 107                 $this->revisionGetTimestampFromIdCallback = $callback;
 108                 return new ScopedCallback( function() use ( $previousValue ) {
 109                         $this->revisionGetTimestampFromIdCallback = $previousValue;
 110                 } );
 111         }
 112
 113         /**
 114          * Overrides the default instance of this class
 115          * This is intended for use while testing and will fail if MW_PHPUNIT_TEST is not defined.
 116          *
 117          * If this method is used it MUST also be called with null after a test to ensure a new
 118          * default instance is created next time getDefaultInstance is called.
 119          *
 120          * @param WatchedItemStore|null $store
 121          *
 122          * @return ScopedCallback to reset the overridden value
 123          * @throws MWException
 124          */
 125         public static function overrideDefaultInstance( WatchedItemStore $store = null ) {
 126                 if ( !defined( 'MW_PHPUNIT_TEST' ) ) {
 127                         throw new MWException(
 128                                 'Cannot override ' . __CLASS__ . 'default instance in operation.'
 129                         );
 130                 }
 131
 132                 $previousValue = self::$instance;
 133                 self::$instance = $store;
 134                 return new ScopedCallback( function() use ( $previousValue ) {
 135                         self::$instance = $previousValue;
 136                 } );
 137         }
 138
 139         /**
 140          * @return self
 141          */
 142         public static function getDefaultInstance() {
 143                 if ( !self::$instance ) {
 144                         self::$instance = new self(
 145                                 wfGetLB(),
 146                                 new HashBagOStuff( [ 'maxKeys' => 100 ] )
 147                         );
 148                 }
 149                 return self::$instance;
 150         }
 151
 152         private function getCacheKey( User $user, LinkTarget $target ) {
 153                 return $this->cache->makeKey(
 154                         (string)$target->getNamespace(),
 155                         $target->getDBkey(),
 156                         (string)$user->getId()
 157                 );
 158         }
 159
 160         private function cache( WatchedItem $item ) {
 161                 $user = $item->getUser();
 162                 $target = $item->getLinkTarget();
 163                 $key = $this->getCacheKey( $user, $target );
 164                 $this->cache->set( $key, $item );
 165                 $this->cacheIndex[$target->getNamespace()][$target->getDBkey()][$user->getId()] = $key;
 166         }
 167
 168         private function uncache( User $user, LinkTarget $target ) {
 169                 $this->cache->delete( $this->getCacheKey( $user, $target ) );
 170                 unset( $this->cacheIndex[$target->getNamespace()][$target->getDBkey()][$user->getId()] );
 171         }
 172
 173         private function uncacheLinkTarget( LinkTarget $target ) {
 174                 if ( !isset( $this->cacheIndex[$target->getNamespace()][$target->getDBkey()] ) ) {
 175                         return;
 176                 }
 177                 foreach ( $this->cacheIndex[$target->getNamespace()][$target->getDBkey()] as $key ) {
 178                         $this->cache->delete( $key );
 179                 }
 180         }
 181
 182         /**
 183          * @param User $user
 184          * @param LinkTarget $target
 185          *
 186          * @return WatchedItem|null
 187          */
 188         private function getCached( User $user, LinkTarget $target ) {
 189                 return $this->cache->get( $this->getCacheKey( $user, $target ) );
 190         }
 191
 192         /**
 193          * Return an array of conditions to select or update the appropriate database
 194          * row.
 195          *
 196          * @param User $user
 197          * @param LinkTarget $target
 198          *
 199          * @return array
 200          */
 201         private function dbCond( User $user, LinkTarget $target ) {
 202                 return [
 203                         'wl_user' => $user->getId(),
 204                         'wl_namespace' => $target->getNamespace(),
 205                         'wl_title' => $target->getDBkey(),
 206                 ];
 207         }
 208
 209         /**
 210          * @param LinkTarget $target
 211          *
 212          * @return int
 213          */
 214         public function countWatchers( LinkTarget $target ) {
 215                 $dbr = $this->loadBalancer->getConnection( DB_SLAVE, [ 'watchlist' ] );
 216                 $return = (int)$dbr->selectField(
 217                         'watchlist',
 218                         'COUNT(*)',
 219                         [
 220                                 'wl_namespace' => $target->getNamespace(),
 221                                 'wl_title' => $target->getDBkey(),
 222                         ],
 223                         __METHOD__
 224                 );
 225                 $this->loadBalancer->reuseConnection( $dbr );
 226
 227                 return $return;
 228         }
 229
 230         /**
 231          * Number of page watchers who also visited a "recent" edit
 232          *
 233          * @param LinkTarget $target
 234          * @param mixed $threshold timestamp accepted by wfTimestamp
 235          *
 236          * @return int
 237          * @throws DBUnexpectedError
 238          * @throws MWException
 239          */
 240         public function countVisitingWatchers( LinkTarget $target, $threshold ) {
 241                 $dbr = $this->loadBalancer->getConnection( DB_SLAVE, [ 'watchlist' ] );
 242                 $visitingWatchers = (int)$dbr->selectField(
 243                         'watchlist',
 244                         'COUNT(*)',
 245                         [
 246                                 'wl_namespace' => $target->getNamespace(),
 247                                 'wl_title' => $target->getDBkey(),
 248                                 'wl_notificationtimestamp >= ' .
 249                                 $dbr->addQuotes( $dbr->timestamp( $threshold ) ) .
 250                                 ' OR wl_notificationtimestamp IS NULL'
 251                         ],
 252                         __METHOD__
 253                 );
 254                 $this->loadBalancer->reuseConnection( $dbr );
 255
 256                 return $visitingWatchers;
 257         }
 258
 259         /**
 260          * @param LinkTarget[] $targets
 261          * @param array $options Allowed keys:
 262          *        'minimumWatchers' => int
 263          *
 264          * @return array multi dimensional like $return[$namespaceId][$titleString] = int $watchers
 265          *         All targets will be present in the result. 0 either means no watchers or the number
 266          *         of watchers was below the minimumWatchers option if passed.
 267          */
 268         public function countWatchersMultiple( array $targets, array $options = [] ) {
 269                 $dbOptions = [ 'GROUP BY' => [ 'wl_namespace', 'wl_title' ] ];
 270
 271                 $dbr = $this->loadBalancer->getConnection( DB_SLAVE, [ 'watchlist' ] );
 272
 273                 if ( array_key_exists( 'minimumWatchers', $options ) ) {
 274                         $dbOptions['HAVING'] = 'COUNT(*) >= ' . (int)$options['minimumWatchers'];
 275                 }
 276
 277                 $lb = new LinkBatch( $targets );
 278                 $res = $dbr->select(
 279                         'watchlist',
 280                         [ 'wl_title', 'wl_namespace', 'watchers' => 'COUNT(*)' ],
 281                         [ $lb->constructSet( 'wl', $dbr ) ],
 282                         __METHOD__,
 283                         $dbOptions
 284                 );
 285
 286                 $this->loadBalancer->reuseConnection( $dbr );
 287
 288                 $watchCounts = [];
 289                 foreach ( $targets as $linkTarget ) {
 290                         $watchCounts[$linkTarget->getNamespace()][$linkTarget->getDBkey()] = 0;
 291                 }
 292
 293                 foreach ( $res as $row ) {
 294                         $watchCounts[$row->wl_namespace][$row->wl_title] = (int)$row->watchers;
 295                 }
 296
 297                 return $watchCounts;
 298         }
 299
 300         /**
 301          * Get an item (may be cached)
 302          *
 303          * @param User $user
 304          * @param LinkTarget $target
 305          *
 306          * @return WatchedItem|false
 307          */
 308         public function getWatchedItem( User $user, LinkTarget $target ) {
 309                 if ( $user->isAnon() ) {
 310                         return false;
 311                 }
 312
 313                 $cached = $this->getCached( $user, $target );
 314                 if ( $cached ) {
 315                         return $cached;
 316                 }
 317                 return $this->loadWatchedItem( $user, $target );
 318         }
 319
 320         /**
 321          * Loads an item from the db
 322          *
 323          * @param User $user
 324          * @param LinkTarget $target
 325          *
 326          * @return WatchedItem|false
 327          */
 328         public function loadWatchedItem( User $user, LinkTarget $target ) {
 329                 // Only loggedin user can have a watchlist
 330                 if ( $user->isAnon() ) {
 331                         return false;
 332                 }
 333
 334                 $dbr = $this->loadBalancer->getConnection( DB_SLAVE, [ 'watchlist' ] );
 335                 $row = $dbr->selectRow(
 336                         'watchlist',
 337                         'wl_notificationtimestamp',
 338                         $this->dbCond( $user, $target ),
 339                         __METHOD__
 340                 );
 341                 $this->loadBalancer->reuseConnection( $dbr );
 342
 343                 if ( !$row ) {
 344                         return false;
 345                 }
 346
 347                 $item = new WatchedItem(
 348                         $user,
 349                         $target,
 350                         $row->wl_notificationtimestamp
 351                 );
 352                 $this->cache( $item );
 353
 354                 return $item;
 355         }
 356
 357         /**
 358          * Must be called separately for Subject & Talk namespaces
 359          *
 360          * @param User $user
 361          * @param LinkTarget $target
 362          *
 363          * @return bool
 364          */
 365         public function isWatched( User $user, LinkTarget $target ) {
 366                 return (bool)$this->getWatchedItem( $user, $target );
 367         }
 368
 369         /**
 370          * Must be called separately for Subject & Talk namespaces
 371          *
 372          * @param User $user
 373          * @param LinkTarget $target
 374          */
 375         public function addWatch( User $user, LinkTarget $target ) {
 376                 $this->addWatchBatch( [ [ $user, $target ] ] );
 377         }
 378
 379         /**
 380          * @param array[] $userTargetCombinations array of arrays containing [0] => User [1] => LinkTarget
 381          *
 382          * @return bool success
 383          */
 384         public function addWatchBatch( array $userTargetCombinations ) {
 385                 if ( $this->loadBalancer->getReadOnlyReason() !== false ) {
 386                         return false;
 387                 }
 388
 389                 $rows = [];
 390                 foreach ( $userTargetCombinations as list( $user, $target ) ) {
 391                         /**
 392                          * @var User $user
 393                          * @var LinkTarget $target
 394                          */
 395
 396                         // Only loggedin user can have a watchlist
 397                         if ( $user->isAnon() ) {
 398                                 continue;
 399                         }
 400                         $rows[] = [
 401                                 'wl_user' => $user->getId(),
 402                                 'wl_namespace' => $target->getNamespace(),
 403                                 'wl_title' => $target->getDBkey(),
 404                                 'wl_notificationtimestamp' => null,
 405                         ];
 406                         $this->uncache( $user, $target );
 407                 }
 408
 409                 if ( !$rows ) {
 410                         return false;
 411                 }
 412
 413                 $dbw = $this->loadBalancer->getConnection( DB_MASTER, [ 'watchlist' ] );
 414                 foreach ( array_chunk( $rows, 100 ) as $toInsert ) {
 415                         // Use INSERT IGNORE to avoid overwriting the notification timestamp
 416                         // if there's already an entry for this page
 417                         $dbw->insert( 'watchlist', $toInsert, __METHOD__, 'IGNORE' );
 418                 }
 419                 $this->loadBalancer->reuseConnection( $dbw );
 420
 421                 return true;
 422         }
 423
 424         /**
 425          * Removes the an entry for the User watching the LinkTarget
 426          * Must be called separately for Subject & Talk namespaces
 427          *
 428          * @param User $user
 429          * @param LinkTarget $target
 430          *
 431          * @return bool success
 432          * @throws DBUnexpectedError
 433          * @throws MWException
 434          */
 435         public function removeWatch( User $user, LinkTarget $target ) {
 436                 // Only logged in user can have a watchlist
 437                 if ( $this->loadBalancer->getReadOnlyReason() !== false || $user->isAnon() ) {
 438                         return false;
 439                 }
 440
 441                 $this->uncache( $user, $target );
 442
 443                 $dbw = $this->loadBalancer->getConnection( DB_MASTER, [ 'watchlist' ] );
 444                 $dbw->delete( 'watchlist',
 445                         [
 446                                 'wl_user' => $user->getId(),
 447                                 'wl_namespace' => $target->getNamespace(),
 448                                 'wl_title' => $target->getDBkey(),
 449                         ], __METHOD__
 450                 );
 451                 $success = (bool)$dbw->affectedRows();
 452                 $this->loadBalancer->reuseConnection( $dbw );
 453
 454                 return $success;
 455         }
 456
 457         /**
 458          * @param User $editor The editor that triggered the update. Their notification
 459          *  timestamp will not be updated(they have already seen it)
 460          * @param LinkTarget $target The target to update timestamps for
 461          * @param string $timestamp Set the update timestamp to this value
 462          *
 463          * @return int[] Array of user IDs the timestamp has been updated for
 464          */
 465         public function updateNotificationTimestamp( User $editor, LinkTarget $target, $timestamp ) {
 466                 $dbw = $this->loadBalancer->getConnection( DB_MASTER, [ 'watchlist' ] );
 467                 $res = $dbw->select( [ 'watchlist' ],
 468                         [ 'wl_user' ],
 469                         [
 470                                 'wl_user != ' . intval( $editor->getId() ),
 471                                 'wl_namespace' => $target->getNamespace(),
 472                                 'wl_title' => $target->getDBkey(),
 473                                 'wl_notificationtimestamp IS NULL',
 474                         ], __METHOD__
 475                 );
 476
 477                 $watchers = [];
 478                 foreach ( $res as $row ) {
 479                         $watchers[] = intval( $row->wl_user );
 480                 }
 481
 482                 if ( $watchers ) {
 483                         // Update wl_notificationtimestamp for all watching users except the editor
 484                         $fname = __METHOD__;
 485                         $dbw->onTransactionIdle(
 486                                 function () use ( $dbw, $timestamp, $watchers, $target, $fname ) {
 487                                         $dbw->update( 'watchlist',
 488                                                 [ /* SET */
 489                                                         'wl_notificationtimestamp' => $dbw->timestamp( $timestamp )
 490                                                 ], [ /* WHERE */
 491                                                         'wl_user' => $watchers,
 492                                                         'wl_namespace' => $target->getNamespace(),
 493                                                         'wl_title' => $target->getDBkey(),
 494                                                 ], $fname
 495                                         );
 496                                         $this->uncacheLinkTarget( $target );
 497                                 }
 498                         );
 499                 }
 500
 501                 $this->loadBalancer->reuseConnection( $dbw );
 502
 503                 return $watchers;
 504         }
 505
 506         /**
 507          * Reset the notification timestamp of this entry
 508          *
 509          * @param User $user
 510          * @param Title $title
 511          * @param string $force Whether to force the write query to be executed even if the
 512          *    page is not watched or the notification timestamp is already NULL.
 513          *    'force' in order to force
 514          * @param int $oldid The revision id being viewed. If not given or 0, latest revision is assumed.
 515          *
 516          * @return bool success
 517          */
 518         public function resetNotificationTimestamp( User $user, Title $title, $force = '', $oldid = 0 ) {
 519                 // Only loggedin user can have a watchlist
 520                 if ( $this->loadBalancer->getReadOnlyReason() !== false || $user->isAnon() ) {
 521                         return false;
 522                 }
 523
 524                 $item = null;
 525                 if ( $force != 'force' ) {
 526                         $item = $this->loadWatchedItem( $user, $title );
 527                         if ( !$item || $item->getNotificationTimestamp() === null ) {
 528                                 return false;
 529                         }
 530                 }
 531
 532                 // If the page is watched by the user (or may be watched), update the timestamp
 533                 $job = new ActivityUpdateJob(
 534                         $title,
 535                         [
 536                                 'type'      => 'updateWatchlistNotification',
 537                                 'userid'    => $user->getId(),
 538                                 'notifTime' => $this->getNotificationTimestamp( $user, $title, $item, $force, $oldid ),
 539                                 'curTime'   => time()
 540                         ]
 541                 );
 542
 543                 // Try to run this post-send
 544                 // Calls DeferredUpdates::addCallableUpdate in normal operation
 545                 call_user_func(
 546                         $this->deferredUpdatesAddCallableUpdateCallback,
 547                         function() use ( $job ) {
 548                                 $job->run();
 549                         }
 550                 );
 551
 552                 $this->uncache( $user, $title );
 553
 554                 return true;
 555         }
 556
 557         private function getNotificationTimestamp( User $user, Title $title, $item, $force, $oldid ) {
 558                 if ( !$oldid ) {
 559                         // No oldid given, assuming latest revision; clear the timestamp.
 560                         return null;
 561                 }
 562
 563                 if ( !$title->getNextRevisionID( $oldid ) ) {
 564                         // Oldid given and is the latest revision for this title; clear the timestamp.
 565                         return null;
 566                 }
 567
 568                 if ( $item === null ) {
 569                         $item = $this->loadWatchedItem( $user, $title );
 570                 }
 571
 572                 if ( !$item ) {
 573                         // This can only happen if $force is enabled.
 574                         return null;
 575                 }
 576
 577                 // Oldid given and isn't the latest; update the timestamp.
 578                 // This will result in no further notification emails being sent!
 579                 // Calls Revision::getTimestampFromId in normal operation
 580                 $notificationTimestamp = call_user_func(
 581                         $this->revisionGetTimestampFromIdCallback,
 582                         $title,
 583                         $oldid
 584                 );
 585
 586                 // We need to go one second to the future because of various strict comparisons
 587                 // throughout the codebase
 588                 $ts = new MWTimestamp( $notificationTimestamp );
 589                 $ts->timestamp->add( new DateInterval( 'PT1S' ) );
 590                 $notificationTimestamp = $ts->getTimestamp( TS_MW );
 591
 592                 if ( $notificationTimestamp < $item->getNotificationTimestamp() ) {
 593                         if ( $force != 'force' ) {
 594                                 return false;
 595                         } else {
 596                                 // This is a little silly…
 597                                 return $item->getNotificationTimestamp();
 598                         }
 599                 }
 600
 601                 return $notificationTimestamp;
 602         }
 603
 604         /**
 605          * @param User $user
 606          * @param int $unreadLimit
 607          *
 608          * @return int|bool The number of unread notifications
 609          *                  true if greater than or equal to $unreadLimit
 610          */
 611         public function countUnreadNotifications( User $user, $unreadLimit = null ) {
 612                 $queryOptions = [];
 613                 if ( $unreadLimit !== null ) {
 614                         $unreadLimit = (int)$unreadLimit;
 615                         $queryOptions['LIMIT'] = $unreadLimit;
 616                 }
 617
 618                 $dbr = $this->loadBalancer->getConnection( DB_SLAVE, [ 'watchlist' ] );
 619                 $rowCount = $dbr->selectRowCount(
 620                         'watchlist',
 621                         '1',
 622                         [
 623                                 'wl_user' => $user->getId(),
 624                                 'wl_notificationtimestamp IS NOT NULL',
 625                         ],
 626                         __METHOD__,
 627                         $queryOptions
 628                 );
 629                 $this->loadBalancer->reuseConnection( $dbr );
 630
 631                 if ( !isset( $unreadLimit ) ) {
 632                         return $rowCount;
 633                 }
 634
 635                 if ( $rowCount >= $unreadLimit ) {
 636                         return true;
 637                 }
 638
 639                 return $rowCount;
 640         }
 641
 642         /**
 643          * Check if the given title already is watched by the user, and if so
 644          * add a watch for the new title.
 645          *
 646          * To be used for page renames and such.
 647          *
 648          * @param LinkTarget $oldTarget
 649          * @param LinkTarget $newTarget
 650          */
 651         public function duplicateAllAssociatedEntries( LinkTarget $oldTarget, LinkTarget $newTarget ) {
 652                 if ( !$oldTarget instanceof Title ) {
 653                         $oldTarget = Title::newFromLinkTarget( $oldTarget );
 654                 }
 655                 if ( !$newTarget instanceof Title ) {
 656                         $newTarget = Title::newFromLinkTarget( $newTarget );
 657                 }
 658
 659                 $this->duplicateEntry( $oldTarget->getSubjectPage(), $newTarget->getSubjectPage() );
 660                 $this->duplicateEntry( $oldTarget->getTalkPage(), $newTarget->getTalkPage() );
 661         }
 662
 663         /**
 664          * Check if the given title already is watched by the user, and if so
 665          * add a watch for the new title.
 666          *
 667          * To be used for page renames and such.
 668          * This must be called separately for Subject and Talk pages
 669          *
 670          * @param LinkTarget $oldTarget
 671          * @param LinkTarget $newTarget
 672          */
 673         public function duplicateEntry( LinkTarget $oldTarget, LinkTarget $newTarget ) {
 674                 $dbw = $this->loadBalancer->getConnection( DB_MASTER, [ 'watchlist' ] );
 675
 676                 $result = $dbw->select(
 677                         'watchlist',
 678                         [ 'wl_user', 'wl_notificationtimestamp' ],
 679                         [
 680                                 'wl_namespace' => $oldTarget->getNamespace(),
 681                                 'wl_title' => $oldTarget->getDBkey(),
 682                         ],
 683                         __METHOD__,
 684                         [ 'FOR UPDATE' ]
 685                 );
 686
 687                 $newNamespace = $newTarget->getNamespace();
 688                 $newDBkey = $newTarget->getDBkey();
 689
 690                 # Construct array to replace into the watchlist
 691                 $values = [];
 692                 foreach ( $result as $row ) {
 693                         $values[] = [
 694                                 'wl_user' => $row->wl_user,
 695                                 'wl_namespace' => $newNamespace,
 696                                 'wl_title' => $newDBkey,
 697                                 'wl_notificationtimestamp' => $row->wl_notificationtimestamp,
 698                         ];
 699                 }
 700
 701                 if ( !empty( $values ) ) {
 702                         # Perform replace
 703                         # Note that multi-row replace is very efficient for MySQL but may be inefficient for
 704                         # some other DBMSes, mostly due to poor simulation by us
 705                         $dbw->replace(
 706                                 'watchlist',
 707                                 [ [ 'wl_user', 'wl_namespace', 'wl_title' ] ],
 708                                 $values,
 709                                 __METHOD__
 710                         );
 711                 }
 712
 713                 $this->loadBalancer->reuseConnection( $dbw );
 714         }
 715
 716 }