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 int $slaveOrMaster DB_MASTER or DB_SLAVE
 211          *
 212          * @return DatabaseBase
 213          * @throws MWException
 214          */
 215         private function getConnection( $slaveOrMaster ) {
 216                 return $this->loadBalancer->getConnection( $slaveOrMaster, [ 'watchlist' ] );
 217         }
 218
 219         /**
 220          * @param DatabaseBase $connection
 221          *
 222          * @throws MWException
 223          */
 224         private function reuseConnection( $connection ) {
 225                 $this->loadBalancer->reuseConnection( $connection );
 226         }
 227
 228         /**
 229          * Count the number of individual items that are watched by the user.
 230          * If a subject and corresponding talk page are watched this will return 2.
 231          *
 232          * @param User $user
 233          *
 234          * @return int
 235          */
 236         public function countWatchedItems( User $user ) {
 237                 $dbr = $this->getConnection( DB_SLAVE );
 238                 $return = (int)$dbr->selectField(
 239                         'watchlist',
 240                         'COUNT(*)',
 241                         [
 242                                 'wl_user' => $user->getId()
 243                         ],
 244                         __METHOD__
 245                 );
 246                 $this->reuseConnection( $dbr );
 247
 248                 return $return;
 249         }
 250
 251         /**
 252          * @param LinkTarget $target
 253          *
 254          * @return int
 255          */
 256         public function countWatchers( LinkTarget $target ) {
 257                 $dbr = $this->getConnection( DB_SLAVE );
 258                 $return = (int)$dbr->selectField(
 259                         'watchlist',
 260                         'COUNT(*)',
 261                         [
 262                                 'wl_namespace' => $target->getNamespace(),
 263                                 'wl_title' => $target->getDBkey(),
 264                         ],
 265                         __METHOD__
 266                 );
 267                 $this->reuseConnection( $dbr );
 268
 269                 return $return;
 270         }
 271
 272         /**
 273          * Number of page watchers who also visited a "recent" edit
 274          *
 275          * @param LinkTarget $target
 276          * @param mixed $threshold timestamp accepted by wfTimestamp
 277          *
 278          * @return int
 279          * @throws DBUnexpectedError
 280          * @throws MWException
 281          */
 282         public function countVisitingWatchers( LinkTarget $target, $threshold ) {
 283                 $dbr = $this->getConnection( DB_SLAVE );
 284                 $visitingWatchers = (int)$dbr->selectField(
 285                         'watchlist',
 286                         'COUNT(*)',
 287                         [
 288                                 'wl_namespace' => $target->getNamespace(),
 289                                 'wl_title' => $target->getDBkey(),
 290                                 'wl_notificationtimestamp >= ' .
 291                                 $dbr->addQuotes( $dbr->timestamp( $threshold ) ) .
 292                                 ' OR wl_notificationtimestamp IS NULL'
 293                         ],
 294                         __METHOD__
 295                 );
 296                 $this->reuseConnection( $dbr );
 297
 298                 return $visitingWatchers;
 299         }
 300
 301         /**
 302          * @param LinkTarget[] $targets
 303          * @param array $options Allowed keys:
 304          *        'minimumWatchers' => int
 305          *
 306          * @return array multi dimensional like $return[$namespaceId][$titleString] = int $watchers
 307          *         All targets will be present in the result. 0 either means no watchers or the number
 308          *         of watchers was below the minimumWatchers option if passed.
 309          */
 310         public function countWatchersMultiple( array $targets, array $options = [] ) {
 311                 $dbOptions = [ 'GROUP BY' => [ 'wl_namespace', 'wl_title' ] ];
 312
 313                 $dbr = $this->getConnection( DB_SLAVE );
 314
 315                 if ( array_key_exists( 'minimumWatchers', $options ) ) {
 316                         $dbOptions['HAVING'] = 'COUNT(*) >= ' . (int)$options['minimumWatchers'];
 317                 }
 318
 319                 $lb = new LinkBatch( $targets );
 320                 $res = $dbr->select(
 321                         'watchlist',
 322                         [ 'wl_title', 'wl_namespace', 'watchers' => 'COUNT(*)' ],
 323                         [ $lb->constructSet( 'wl', $dbr ) ],
 324                         __METHOD__,
 325                         $dbOptions
 326                 );
 327
 328                 $this->reuseConnection( $dbr );
 329
 330                 $watchCounts = [];
 331                 foreach ( $targets as $linkTarget ) {
 332                         $watchCounts[$linkTarget->getNamespace()][$linkTarget->getDBkey()] = 0;
 333                 }
 334
 335                 foreach ( $res as $row ) {
 336                         $watchCounts[$row->wl_namespace][$row->wl_title] = (int)$row->watchers;
 337                 }
 338
 339                 return $watchCounts;
 340         }
 341
 342         /**
 343          * Number of watchers of each page who have visited recent edits to that page
 344          *
 345          * @param array $targetsWithVisitThresholds array of pairs (LinkTarget $target, mixed $threshold),
 346          *        $threshold is:
 347          *        - a timestamp of the recent edit if $target exists (format accepted by wfTimestamp)
 348          *        - null if $target doesn't exist
 349          * @param int|null $minimumWatchers
 350          * @return array multi-dimensional like $return[$namespaceId][$titleString] = $watchers,
 351          *         where $watchers is an int:
 352          *         - if the page exists, number of users watching who have visited the page recently
 353          *         - if the page doesn't exist, number of users that have the page on their watchlist
 354          *         - 0 means there are no visiting watchers or their number is below the minimumWatchers
 355          *         option (if passed).
 356          */
 357         public function countVisitingWatchersMultiple(
 358                 array $targetsWithVisitThresholds,
 359                 $minimumWatchers = null
 360         ) {
 361                 $dbr = $this->getConnection( DB_SLAVE );
 362
 363                 $conds = $this->getVisitingWatchersCondition( $dbr, $targetsWithVisitThresholds );
 364
 365                 $dbOptions = [ 'GROUP BY' => [ 'wl_namespace', 'wl_title' ] ];
 366                 if ( $minimumWatchers !== null ) {
 367                         $dbOptions['HAVING'] = 'COUNT(*) >= ' . (int)$minimumWatchers;
 368                 }
 369                 $res = $dbr->select(
 370                         'watchlist',
 371                         [ 'wl_namespace', 'wl_title', 'watchers' => 'COUNT(*)' ],
 372                         $conds,
 373                         __METHOD__,
 374                         $dbOptions
 375                 );
 376
 377                 $this->reuseConnection( $dbr );
 378
 379                 $watcherCounts = [];
 380                 foreach ( $targetsWithVisitThresholds as list( $target ) ) {
 381                         /* @var LinkTarget $target */
 382                         $watcherCounts[$target->getNamespace()][$target->getDBkey()] = 0;
 383                 }
 384
 385                 foreach ( $res as $row ) {
 386                         $watcherCounts[$row->wl_namespace][$row->wl_title] = (int)$row->watchers;
 387                 }
 388
 389                 return $watcherCounts;
 390         }
 391
 392         /**
 393          * Generates condition for the query used in a batch count visiting watchers.
 394          *
 395          * @param IDatabase $db
 396          * @param array $targetsWithVisitThresholds array of pairs (LinkTarget, last visit threshold)
 397          * @return string
 398          */
 399         private function getVisitingWatchersCondition(
 400                 IDatabase $db,
 401                 array $targetsWithVisitThresholds
 402         ) {
 403                 $missingTargets = [];
 404                 $namespaceConds = [];
 405                 foreach ( $targetsWithVisitThresholds as list( $target, $threshold ) ) {
 406                         if ( $threshold === null ) {
 407                                 $missingTargets[] = $target;
 408                                 continue;
 409                         }
 410                         /* @var LinkTarget $target */
 411                         $namespaceConds[$target->getNamespace()][] = $db->makeList( [
 412                                 'wl_title = ' . $db->addQuotes( $target->getDBkey() ),
 413                                 $db->makeList( [
 414                                         'wl_notificationtimestamp >= ' . $db->addQuotes( $db->timestamp( $threshold ) ),
 415                                         'wl_notificationtimestamp IS NULL'
 416                                 ], LIST_OR )
 417                         ], LIST_AND );
 418                 }
 419
 420                 $conds = [];
 421                 foreach ( $namespaceConds as $namespace => $pageConds ) {
 422                         $conds[] = $db->makeList( [
 423                                 'wl_namespace = ' . $namespace,
 424                                 '(' . $db->makeList( $pageConds, LIST_OR ) . ')'
 425                         ], LIST_AND );
 426                 }
 427
 428                 if ( $missingTargets ) {
 429                         $lb = new LinkBatch( $missingTargets );
 430                         $conds[] = $lb->constructSet( 'wl', $db );
 431                 }
 432
 433                 return $db->makeList( $conds, LIST_OR );
 434         }
 435
 436         /**
 437          * Get an item (may be cached)
 438          *
 439          * @param User $user
 440          * @param LinkTarget $target
 441          *
 442          * @return WatchedItem|false
 443          */
 444         public function getWatchedItem( User $user, LinkTarget $target ) {
 445                 if ( $user->isAnon() ) {
 446                         return false;
 447                 }
 448
 449                 $cached = $this->getCached( $user, $target );
 450                 if ( $cached ) {
 451                         return $cached;
 452                 }
 453                 return $this->loadWatchedItem( $user, $target );
 454         }
 455
 456         /**
 457          * Loads an item from the db
 458          *
 459          * @param User $user
 460          * @param LinkTarget $target
 461          *
 462          * @return WatchedItem|false
 463          */
 464         public function loadWatchedItem( User $user, LinkTarget $target ) {
 465                 // Only loggedin user can have a watchlist
 466                 if ( $user->isAnon() ) {
 467                         return false;
 468                 }
 469
 470                 $dbr = $this->getConnection( DB_SLAVE );
 471                 $row = $dbr->selectRow(
 472                         'watchlist',
 473                         'wl_notificationtimestamp',
 474                         $this->dbCond( $user, $target ),
 475                         __METHOD__
 476                 );
 477                 $this->reuseConnection( $dbr );
 478
 479                 if ( !$row ) {
 480                         return false;
 481                 }
 482
 483                 $item = new WatchedItem(
 484                         $user,
 485                         $target,
 486                         $row->wl_notificationtimestamp
 487                 );
 488                 $this->cache( $item );
 489
 490                 return $item;
 491         }
 492
 493         /**
 494          * Must be called separately for Subject & Talk namespaces
 495          *
 496          * @param User $user
 497          * @param LinkTarget $target
 498          *
 499          * @return bool
 500          */
 501         public function isWatched( User $user, LinkTarget $target ) {
 502                 return (bool)$this->getWatchedItem( $user, $target );
 503         }
 504
 505         /**
 506          * Must be called separately for Subject & Talk namespaces
 507          *
 508          * @param User $user
 509          * @param LinkTarget $target
 510          */
 511         public function addWatch( User $user, LinkTarget $target ) {
 512                 $this->addWatchBatch( [ [ $user, $target ] ] );
 513         }
 514
 515         /**
 516          * @param array[] $userTargetCombinations array of arrays containing [0] => User [1] => LinkTarget
 517          *
 518          * @return bool success
 519          */
 520         public function addWatchBatch( array $userTargetCombinations ) {
 521                 if ( $this->loadBalancer->getReadOnlyReason() !== false ) {
 522                         return false;
 523                 }
 524
 525                 $rows = [];
 526                 foreach ( $userTargetCombinations as list( $user, $target ) ) {
 527                         /**
 528                          * @var User $user
 529                          * @var LinkTarget $target
 530                          */
 531
 532                         // Only loggedin user can have a watchlist
 533                         if ( $user->isAnon() ) {
 534                                 continue;
 535                         }
 536                         $rows[] = [
 537                                 'wl_user' => $user->getId(),
 538                                 'wl_namespace' => $target->getNamespace(),
 539                                 'wl_title' => $target->getDBkey(),
 540                                 'wl_notificationtimestamp' => null,
 541                         ];
 542                         $this->uncache( $user, $target );
 543                 }
 544
 545                 if ( !$rows ) {
 546                         return false;
 547                 }
 548
 549                 $dbw = $this->getConnection( DB_MASTER );
 550                 foreach ( array_chunk( $rows, 100 ) as $toInsert ) {
 551                         // Use INSERT IGNORE to avoid overwriting the notification timestamp
 552                         // if there's already an entry for this page
 553                         $dbw->insert( 'watchlist', $toInsert, __METHOD__, 'IGNORE' );
 554                 }
 555                 $this->reuseConnection( $dbw );
 556
 557                 return true;
 558         }
 559
 560         /**
 561          * Removes the an entry for the User watching the LinkTarget
 562          * Must be called separately for Subject & Talk namespaces
 563          *
 564          * @param User $user
 565          * @param LinkTarget $target
 566          *
 567          * @return bool success
 568          * @throws DBUnexpectedError
 569          * @throws MWException
 570          */
 571         public function removeWatch( User $user, LinkTarget $target ) {
 572                 // Only logged in user can have a watchlist
 573                 if ( $this->loadBalancer->getReadOnlyReason() !== false || $user->isAnon() ) {
 574                         return false;
 575                 }
 576
 577                 $this->uncache( $user, $target );
 578
 579                 $dbw = $this->getConnection( DB_MASTER );
 580                 $dbw->delete( 'watchlist',
 581                         [
 582                                 'wl_user' => $user->getId(),
 583                                 'wl_namespace' => $target->getNamespace(),
 584                                 'wl_title' => $target->getDBkey(),
 585                         ], __METHOD__
 586                 );
 587                 $success = (bool)$dbw->affectedRows();
 588                 $this->reuseConnection( $dbw );
 589
 590                 return $success;
 591         }
 592
 593         /**
 594          * @param User $editor The editor that triggered the update. Their notification
 595          *  timestamp will not be updated(they have already seen it)
 596          * @param LinkTarget $target The target to update timestamps for
 597          * @param string $timestamp Set the update timestamp to this value
 598          *
 599          * @return int[] Array of user IDs the timestamp has been updated for
 600          */
 601         public function updateNotificationTimestamp( User $editor, LinkTarget $target, $timestamp ) {
 602                 $dbw = $this->getConnection( DB_MASTER );
 603                 $res = $dbw->select( [ 'watchlist' ],
 604                         [ 'wl_user' ],
 605                         [
 606                                 'wl_user != ' . intval( $editor->getId() ),
 607                                 'wl_namespace' => $target->getNamespace(),
 608                                 'wl_title' => $target->getDBkey(),
 609                                 'wl_notificationtimestamp IS NULL',
 610                         ], __METHOD__
 611                 );
 612
 613                 $watchers = [];
 614                 foreach ( $res as $row ) {
 615                         $watchers[] = intval( $row->wl_user );
 616                 }
 617
 618                 if ( $watchers ) {
 619                         // Update wl_notificationtimestamp for all watching users except the editor
 620                         $fname = __METHOD__;
 621                         $dbw->onTransactionIdle(
 622                                 function () use ( $dbw, $timestamp, $watchers, $target, $fname ) {
 623                                         $dbw->update( 'watchlist',
 624                                                 [ /* SET */
 625                                                         'wl_notificationtimestamp' => $dbw->timestamp( $timestamp )
 626                                                 ], [ /* WHERE */
 627                                                         'wl_user' => $watchers,
 628                                                         'wl_namespace' => $target->getNamespace(),
 629                                                         'wl_title' => $target->getDBkey(),
 630                                                 ], $fname
 631                                         );
 632                                         $this->uncacheLinkTarget( $target );
 633                                 }
 634                         );
 635                 }
 636
 637                 $this->reuseConnection( $dbw );
 638
 639                 return $watchers;
 640         }
 641
 642         /**
 643          * Reset the notification timestamp of this entry
 644          *
 645          * @param User $user
 646          * @param Title $title
 647          * @param string $force Whether to force the write query to be executed even if the
 648          *    page is not watched or the notification timestamp is already NULL.
 649          *    'force' in order to force
 650          * @param int $oldid The revision id being viewed. If not given or 0, latest revision is assumed.
 651          *
 652          * @return bool success
 653          */
 654         public function resetNotificationTimestamp( User $user, Title $title, $force = '', $oldid = 0 ) {
 655                 // Only loggedin user can have a watchlist
 656                 if ( $this->loadBalancer->getReadOnlyReason() !== false || $user->isAnon() ) {
 657                         return false;
 658                 }
 659
 660                 $item = null;
 661                 if ( $force != 'force' ) {
 662                         $item = $this->loadWatchedItem( $user, $title );
 663                         if ( !$item || $item->getNotificationTimestamp() === null ) {
 664                                 return false;
 665                         }
 666                 }
 667
 668                 // If the page is watched by the user (or may be watched), update the timestamp
 669                 $job = new ActivityUpdateJob(
 670                         $title,
 671                         [
 672                                 'type'      => 'updateWatchlistNotification',
 673                                 'userid'    => $user->getId(),
 674                                 'notifTime' => $this->getNotificationTimestamp( $user, $title, $item, $force, $oldid ),
 675                                 'curTime'   => time()
 676                         ]
 677                 );
 678
 679                 // Try to run this post-send
 680                 // Calls DeferredUpdates::addCallableUpdate in normal operation
 681                 call_user_func(
 682                         $this->deferredUpdatesAddCallableUpdateCallback,
 683                         function() use ( $job ) {
 684                                 $job->run();
 685                         }
 686                 );
 687
 688                 $this->uncache( $user, $title );
 689
 690                 return true;
 691         }
 692
 693         private function getNotificationTimestamp( User $user, Title $title, $item, $force, $oldid ) {
 694                 if ( !$oldid ) {
 695                         // No oldid given, assuming latest revision; clear the timestamp.
 696                         return null;
 697                 }
 698
 699                 if ( !$title->getNextRevisionID( $oldid ) ) {
 700                         // Oldid given and is the latest revision for this title; clear the timestamp.
 701                         return null;
 702                 }
 703
 704                 if ( $item === null ) {
 705                         $item = $this->loadWatchedItem( $user, $title );
 706                 }
 707
 708                 if ( !$item ) {
 709                         // This can only happen if $force is enabled.
 710                         return null;
 711                 }
 712
 713                 // Oldid given and isn't the latest; update the timestamp.
 714                 // This will result in no further notification emails being sent!
 715                 // Calls Revision::getTimestampFromId in normal operation
 716                 $notificationTimestamp = call_user_func(
 717                         $this->revisionGetTimestampFromIdCallback,
 718                         $title,
 719                         $oldid
 720                 );
 721
 722                 // We need to go one second to the future because of various strict comparisons
 723                 // throughout the codebase
 724                 $ts = new MWTimestamp( $notificationTimestamp );
 725                 $ts->timestamp->add( new DateInterval( 'PT1S' ) );
 726                 $notificationTimestamp = $ts->getTimestamp( TS_MW );
 727
 728                 if ( $notificationTimestamp < $item->getNotificationTimestamp() ) {
 729                         if ( $force != 'force' ) {
 730                                 return false;
 731                         } else {
 732                                 // This is a little silly…
 733                                 return $item->getNotificationTimestamp();
 734                         }
 735                 }
 736
 737                 return $notificationTimestamp;
 738         }
 739
 740         /**
 741          * @param User $user
 742          * @param int $unreadLimit
 743          *
 744          * @return int|bool The number of unread notifications
 745          *                  true if greater than or equal to $unreadLimit
 746          */
 747         public function countUnreadNotifications( User $user, $unreadLimit = null ) {
 748                 $queryOptions = [];
 749                 if ( $unreadLimit !== null ) {
 750                         $unreadLimit = (int)$unreadLimit;
 751                         $queryOptions['LIMIT'] = $unreadLimit;
 752                 }
 753
 754                 $dbr = $this->getConnection( DB_SLAVE );
 755                 $rowCount = $dbr->selectRowCount(
 756                         'watchlist',
 757                         '1',
 758                         [
 759                                 'wl_user' => $user->getId(),
 760                                 'wl_notificationtimestamp IS NOT NULL',
 761                         ],
 762                         __METHOD__,
 763                         $queryOptions
 764                 );
 765                 $this->reuseConnection( $dbr );
 766
 767                 if ( !isset( $unreadLimit ) ) {
 768                         return $rowCount;
 769                 }
 770
 771                 if ( $rowCount >= $unreadLimit ) {
 772                         return true;
 773                 }
 774
 775                 return $rowCount;
 776         }
 777
 778         /**
 779          * Check if the given title already is watched by the user, and if so
 780          * add a watch for the new title.
 781          *
 782          * To be used for page renames and such.
 783          *
 784          * @param LinkTarget $oldTarget
 785          * @param LinkTarget $newTarget
 786          */
 787         public function duplicateAllAssociatedEntries( LinkTarget $oldTarget, LinkTarget $newTarget ) {
 788                 if ( !$oldTarget instanceof Title ) {
 789                         $oldTarget = Title::newFromLinkTarget( $oldTarget );
 790                 }
 791                 if ( !$newTarget instanceof Title ) {
 792                         $newTarget = Title::newFromLinkTarget( $newTarget );
 793                 }
 794
 795                 $this->duplicateEntry( $oldTarget->getSubjectPage(), $newTarget->getSubjectPage() );
 796                 $this->duplicateEntry( $oldTarget->getTalkPage(), $newTarget->getTalkPage() );
 797         }
 798
 799         /**
 800          * Check if the given title already is watched by the user, and if so
 801          * add a watch for the new title.
 802          *
 803          * To be used for page renames and such.
 804          * This must be called separately for Subject and Talk pages
 805          *
 806          * @param LinkTarget $oldTarget
 807          * @param LinkTarget $newTarget
 808          */
 809         public function duplicateEntry( LinkTarget $oldTarget, LinkTarget $newTarget ) {
 810                 $dbw = $this->getConnection( DB_MASTER );
 811
 812                 $result = $dbw->select(
 813                         'watchlist',
 814                         [ 'wl_user', 'wl_notificationtimestamp' ],
 815                         [
 816                                 'wl_namespace' => $oldTarget->getNamespace(),
 817                                 'wl_title' => $oldTarget->getDBkey(),
 818                         ],
 819                         __METHOD__,
 820                         [ 'FOR UPDATE' ]
 821                 );
 822
 823                 $newNamespace = $newTarget->getNamespace();
 824                 $newDBkey = $newTarget->getDBkey();
 825
 826                 # Construct array to replace into the watchlist
 827                 $values = [];
 828                 foreach ( $result as $row ) {
 829                         $values[] = [
 830                                 'wl_user' => $row->wl_user,
 831                                 'wl_namespace' => $newNamespace,
 832                                 'wl_title' => $newDBkey,
 833                                 'wl_notificationtimestamp' => $row->wl_notificationtimestamp,
 834                         ];
 835                 }
 836
 837                 if ( !empty( $values ) ) {
 838                         # Perform replace
 839                         # Note that multi-row replace is very efficient for MySQL but may be inefficient for
 840                         # some other DBMSes, mostly due to poor simulation by us
 841                         $dbw->replace(
 842                                 'watchlist',
 843                                 [ [ 'wl_user', 'wl_namespace', 'wl_title' ] ],
 844                                 $values,
 845                                 __METHOD__
 846                         );
 847                 }
 848
 849                 $this->reuseConnection( $dbw );
 850         }
 851
 852 }