includes/WatchedItemStore.php

   1 <?php
   2
   3 use Liuggio\StatsdClient\Factory\StatsdDataFactoryInterface;
   4 use Wikimedia\Assert\Assert;
   5
   6 /**
   7  * Storage layer class for WatchedItems.
   8  * Database interaction.
   9  *
  10  * @author Addshore
  11  *
  12  * @since 1.27
  13  */
  14 class WatchedItemStore {
  15
  16         const SORT_DESC = 'DESC';
  17         const SORT_ASC = 'ASC';
  18
  19         /**
  20          * @var LoadBalancer
  21          */
  22         private $loadBalancer;
  23
  24         /**
  25          * @var HashBagOStuff
  26          */
  27         private $cache;
  28
  29         /**
  30          * @var array[] Looks like $cacheIndex[Namespace ID][Target DB Key][User Id] => 'key'
  31          * The index is needed so that on mass changes all relevant items can be un-cached.
  32          * For example: Clearing a users watchlist of all items or updating notification timestamps
  33          *              for all users watching a single target.
  34          */
  35         private $cacheIndex = [];
  36
  37         /**
  38          * @var callable|null
  39          */
  40         private $deferredUpdatesAddCallableUpdateCallback;
  41
  42         /**
  43          * @var callable|null
  44          */
  45         private $revisionGetTimestampFromIdCallback;
  46
  47         /**
  48          * @var StatsdDataFactoryInterface
  49          */
  50         private $stats;
  51
  52         /**
  53          * @var self|null
  54          */
  55         private static $instance;
  56
  57         /**
  58          * @param LoadBalancer $loadBalancer
  59          * @param HashBagOStuff $cache
  60          * @param StatsdDataFactoryInterface $stats
  61          */
  62         public function __construct(
  63                 LoadBalancer $loadBalancer,
  64                 HashBagOStuff $cache,
  65                 StatsdDataFactoryInterface $stats
  66         ) {
  67                 $this->loadBalancer = $loadBalancer;
  68                 $this->cache = $cache;
  69                 $this->stats = $stats;
  70                 $this->deferredUpdatesAddCallableUpdateCallback = [ 'DeferredUpdates', 'addCallableUpdate' ];
  71                 $this->revisionGetTimestampFromIdCallback = [ 'Revision', 'getTimestampFromId' ];
  72         }
  73
  74         /**
  75          * Overrides the DeferredUpdates::addCallableUpdate callback
  76          * This is intended for use while testing and will fail if MW_PHPUNIT_TEST is not defined.
  77          *
  78          * @param callable $callback
  79          *
  80          * @see DeferredUpdates::addCallableUpdate for callback signiture
  81          *
  82          * @return ScopedCallback to reset the overridden value
  83          * @throws MWException
  84          */
  85         public function overrideDeferredUpdatesAddCallableUpdateCallback( $callback ) {
  86                 if ( !defined( 'MW_PHPUNIT_TEST' ) ) {
  87                         throw new MWException(
  88                                 'Cannot override DeferredUpdates::addCallableUpdate callback in operation.'
  89                         );
  90                 }
  91                 Assert::parameterType( 'callable', $callback, '$callback' );
  92
  93                 $previousValue = $this->deferredUpdatesAddCallableUpdateCallback;
  94                 $this->deferredUpdatesAddCallableUpdateCallback = $callback;
  95                 return new ScopedCallback( function() use ( $previousValue ) {
  96                         $this->deferredUpdatesAddCallableUpdateCallback = $previousValue;
  97                 } );
  98         }
  99
 100         /**
 101          * Overrides the Revision::getTimestampFromId callback
 102          * This is intended for use while testing and will fail if MW_PHPUNIT_TEST is not defined.
 103          *
 104          * @param callable $callback
 105          * @see Revision::getTimestampFromId for callback signiture
 106          *
 107          * @return ScopedCallback to reset the overridden value
 108          * @throws MWException
 109          */
 110         public function overrideRevisionGetTimestampFromIdCallback( $callback ) {
 111                 if ( !defined( 'MW_PHPUNIT_TEST' ) ) {
 112                         throw new MWException(
 113                                 'Cannot override Revision::getTimestampFromId callback in operation.'
 114                         );
 115                 }
 116                 Assert::parameterType( 'callable', $callback, '$callback' );
 117
 118                 $previousValue = $this->revisionGetTimestampFromIdCallback;
 119                 $this->revisionGetTimestampFromIdCallback = $callback;
 120                 return new ScopedCallback( function() use ( $previousValue ) {
 121                         $this->revisionGetTimestampFromIdCallback = $previousValue;
 122                 } );
 123         }
 124
 125         /**
 126          * Overrides the default instance of this class
 127          * This is intended for use while testing and will fail if MW_PHPUNIT_TEST is not defined.
 128          *
 129          * If this method is used it MUST also be called with null after a test to ensure a new
 130          * default instance is created next time getDefaultInstance is called.
 131          *
 132          * @param WatchedItemStore|null $store
 133          *
 134          * @return ScopedCallback to reset the overridden value
 135          * @throws MWException
 136          */
 137         public static function overrideDefaultInstance( WatchedItemStore $store = null ) {
 138                 if ( !defined( 'MW_PHPUNIT_TEST' ) ) {
 139                         throw new MWException(
 140                                 'Cannot override ' . __CLASS__ . 'default instance in operation.'
 141                         );
 142                 }
 143
 144                 $previousValue = self::$instance;
 145                 self::$instance = $store;
 146                 return new ScopedCallback( function() use ( $previousValue ) {
 147                         self::$instance = $previousValue;
 148                 } );
 149         }
 150
 151         /**
 152          * @return self
 153          */
 154         public static function getDefaultInstance() {
 155                 if ( !self::$instance ) {
 156                         self::$instance = new self(
 157                                 wfGetLB(),
 158                                 new HashBagOStuff( [ 'maxKeys' => 100 ] ),
 159                                 RequestContext::getMain()->getStats()
 160                         );
 161                 }
 162                 return self::$instance;
 163         }
 164
 165         private function getCacheKey( User $user, LinkTarget $target ) {
 166                 return $this->cache->makeKey(
 167                         (string)$target->getNamespace(),
 168                         $target->getDBkey(),
 169                         (string)$user->getId()
 170                 );
 171         }
 172
 173         private function cache( WatchedItem $item ) {
 174                 $user = $item->getUser();
 175                 $target = $item->getLinkTarget();
 176                 $key = $this->getCacheKey( $user, $target );
 177                 $this->cache->set( $key, $item );
 178                 $this->cacheIndex[$target->getNamespace()][$target->getDBkey()][$user->getId()] = $key;
 179                 $this->stats->increment( 'WatchedItemStore.cache' );
 180         }
 181
 182         private function uncache( User $user, LinkTarget $target ) {
 183                 $this->cache->delete( $this->getCacheKey( $user, $target ) );
 184                 unset( $this->cacheIndex[$target->getNamespace()][$target->getDBkey()][$user->getId()] );
 185                 $this->stats->increment( 'WatchedItemStore.uncache' );
 186         }
 187
 188         private function uncacheLinkTarget( LinkTarget $target ) {
 189                 if ( !isset( $this->cacheIndex[$target->getNamespace()][$target->getDBkey()] ) ) {
 190                         return;
 191                 }
 192                 $this->stats->increment( 'WatchedItemStore.uncacheLinkTarget' );
 193                 foreach ( $this->cacheIndex[$target->getNamespace()][$target->getDBkey()] as $key ) {
 194                         $this->stats->increment( 'WatchedItemStore.uncacheLinkTarget.items' );
 195                         $this->cache->delete( $key );
 196                 }
 197         }
 198
 199         /**
 200          * @param User $user
 201          * @param LinkTarget $target
 202          *
 203          * @return WatchedItem|null
 204          */
 205         private function getCached( User $user, LinkTarget $target ) {
 206                 return $this->cache->get( $this->getCacheKey( $user, $target ) );
 207         }
 208
 209         /**
 210          * Return an array of conditions to select or update the appropriate database
 211          * row.
 212          *
 213          * @param User $user
 214          * @param LinkTarget $target
 215          *
 216          * @return array
 217          */
 218         private function dbCond( User $user, LinkTarget $target ) {
 219                 return [
 220                         'wl_user' => $user->getId(),
 221                         'wl_namespace' => $target->getNamespace(),
 222                         'wl_title' => $target->getDBkey(),
 223                 ];
 224         }
 225
 226         /**
 227          * @param int $slaveOrMaster DB_MASTER or DB_SLAVE
 228          *
 229          * @return DatabaseBase
 230          * @throws MWException
 231          */
 232         private function getConnection( $slaveOrMaster ) {
 233                 return $this->loadBalancer->getConnection( $slaveOrMaster, [ 'watchlist' ] );
 234         }
 235
 236         /**
 237          * @param DatabaseBase $connection
 238          *
 239          * @throws MWException
 240          */
 241         private function reuseConnection( $connection ) {
 242                 $this->loadBalancer->reuseConnection( $connection );
 243         }
 244
 245         /**
 246          * Count the number of individual items that are watched by the user.
 247          * If a subject and corresponding talk page are watched this will return 2.
 248          *
 249          * @param User $user
 250          *
 251          * @return int
 252          */
 253         public function countWatchedItems( User $user ) {
 254                 $dbr = $this->getConnection( DB_SLAVE );
 255                 $return = (int)$dbr->selectField(
 256                         'watchlist',
 257                         'COUNT(*)',
 258                         [
 259                                 'wl_user' => $user->getId()
 260                         ],
 261                         __METHOD__
 262                 );
 263                 $this->reuseConnection( $dbr );
 264
 265                 return $return;
 266         }
 267
 268         /**
 269          * @param LinkTarget $target
 270          *
 271          * @return int
 272          */
 273         public function countWatchers( LinkTarget $target ) {
 274                 $dbr = $this->getConnection( DB_SLAVE );
 275                 $return = (int)$dbr->selectField(
 276                         'watchlist',
 277                         'COUNT(*)',
 278                         [
 279                                 'wl_namespace' => $target->getNamespace(),
 280                                 'wl_title' => $target->getDBkey(),
 281                         ],
 282                         __METHOD__
 283                 );
 284                 $this->reuseConnection( $dbr );
 285
 286                 return $return;
 287         }
 288
 289         /**
 290          * Number of page watchers who also visited a "recent" edit
 291          *
 292          * @param LinkTarget $target
 293          * @param mixed $threshold timestamp accepted by wfTimestamp
 294          *
 295          * @return int
 296          * @throws DBUnexpectedError
 297          * @throws MWException
 298          */
 299         public function countVisitingWatchers( LinkTarget $target, $threshold ) {
 300                 $dbr = $this->getConnection( DB_SLAVE );
 301                 $visitingWatchers = (int)$dbr->selectField(
 302                         'watchlist',
 303                         'COUNT(*)',
 304                         [
 305                                 'wl_namespace' => $target->getNamespace(),
 306                                 'wl_title' => $target->getDBkey(),
 307                                 'wl_notificationtimestamp >= ' .
 308                                 $dbr->addQuotes( $dbr->timestamp( $threshold ) ) .
 309                                 ' OR wl_notificationtimestamp IS NULL'
 310                         ],
 311                         __METHOD__
 312                 );
 313                 $this->reuseConnection( $dbr );
 314
 315                 return $visitingWatchers;
 316         }
 317
 318         /**
 319          * @param LinkTarget[] $targets
 320          * @param array $options Allowed keys:
 321          *        'minimumWatchers' => int
 322          *
 323          * @return array multi dimensional like $return[$namespaceId][$titleString] = int $watchers
 324          *         All targets will be present in the result. 0 either means no watchers or the number
 325          *         of watchers was below the minimumWatchers option if passed.
 326          */
 327         public function countWatchersMultiple( array $targets, array $options = [] ) {
 328                 $dbOptions = [ 'GROUP BY' => [ 'wl_namespace', 'wl_title' ] ];
 329
 330                 $dbr = $this->getConnection( DB_SLAVE );
 331
 332                 if ( array_key_exists( 'minimumWatchers', $options ) ) {
 333                         $dbOptions['HAVING'] = 'COUNT(*) >= ' . (int)$options['minimumWatchers'];
 334                 }
 335
 336                 $lb = new LinkBatch( $targets );
 337                 $res = $dbr->select(
 338                         'watchlist',
 339                         [ 'wl_title', 'wl_namespace', 'watchers' => 'COUNT(*)' ],
 340                         [ $lb->constructSet( 'wl', $dbr ) ],
 341                         __METHOD__,
 342                         $dbOptions
 343                 );
 344
 345                 $this->reuseConnection( $dbr );
 346
 347                 $watchCounts = [];
 348                 foreach ( $targets as $linkTarget ) {
 349                         $watchCounts[$linkTarget->getNamespace()][$linkTarget->getDBkey()] = 0;
 350                 }
 351
 352                 foreach ( $res as $row ) {
 353                         $watchCounts[$row->wl_namespace][$row->wl_title] = (int)$row->watchers;
 354                 }
 355
 356                 return $watchCounts;
 357         }
 358
 359         /**
 360          * Number of watchers of each page who have visited recent edits to that page
 361          *
 362          * @param array $targetsWithVisitThresholds array of pairs (LinkTarget $target, mixed $threshold),
 363          *        $threshold is:
 364          *        - a timestamp of the recent edit if $target exists (format accepted by wfTimestamp)
 365          *        - null if $target doesn't exist
 366          * @param int|null $minimumWatchers
 367          * @return array multi-dimensional like $return[$namespaceId][$titleString] = $watchers,
 368          *         where $watchers is an int:
 369          *         - if the page exists, number of users watching who have visited the page recently
 370          *         - if the page doesn't exist, number of users that have the page on their watchlist
 371          *         - 0 means there are no visiting watchers or their number is below the minimumWatchers
 372          *         option (if passed).
 373          */
 374         public function countVisitingWatchersMultiple(
 375                 array $targetsWithVisitThresholds,
 376                 $minimumWatchers = null
 377         ) {
 378                 $dbr = $this->getConnection( DB_SLAVE );
 379
 380                 $conds = $this->getVisitingWatchersCondition( $dbr, $targetsWithVisitThresholds );
 381
 382                 $dbOptions = [ 'GROUP BY' => [ 'wl_namespace', 'wl_title' ] ];
 383                 if ( $minimumWatchers !== null ) {
 384                         $dbOptions['HAVING'] = 'COUNT(*) >= ' . (int)$minimumWatchers;
 385                 }
 386                 $res = $dbr->select(
 387                         'watchlist',
 388                         [ 'wl_namespace', 'wl_title', 'watchers' => 'COUNT(*)' ],
 389                         $conds,
 390                         __METHOD__,
 391                         $dbOptions
 392                 );
 393
 394                 $this->reuseConnection( $dbr );
 395
 396                 $watcherCounts = [];
 397                 foreach ( $targetsWithVisitThresholds as list( $target ) ) {
 398                         /* @var LinkTarget $target */
 399                         $watcherCounts[$target->getNamespace()][$target->getDBkey()] = 0;
 400                 }
 401
 402                 foreach ( $res as $row ) {
 403                         $watcherCounts[$row->wl_namespace][$row->wl_title] = (int)$row->watchers;
 404                 }
 405
 406                 return $watcherCounts;
 407         }
 408
 409         /**
 410          * Generates condition for the query used in a batch count visiting watchers.
 411          *
 412          * @param IDatabase $db
 413          * @param array $targetsWithVisitThresholds array of pairs (LinkTarget, last visit threshold)
 414          * @return string
 415          */
 416         private function getVisitingWatchersCondition(
 417                 IDatabase $db,
 418                 array $targetsWithVisitThresholds
 419         ) {
 420                 $missingTargets = [];
 421                 $namespaceConds = [];
 422                 foreach ( $targetsWithVisitThresholds as list( $target, $threshold ) ) {
 423                         if ( $threshold === null ) {
 424                                 $missingTargets[] = $target;
 425                                 continue;
 426                         }
 427                         /* @var LinkTarget $target */
 428                         $namespaceConds[$target->getNamespace()][] = $db->makeList( [
 429                                 'wl_title = ' . $db->addQuotes( $target->getDBkey() ),
 430                                 $db->makeList( [
 431                                         'wl_notificationtimestamp >= ' . $db->addQuotes( $db->timestamp( $threshold ) ),
 432                                         'wl_notificationtimestamp IS NULL'
 433                                 ], LIST_OR )
 434                         ], LIST_AND );
 435                 }
 436
 437                 $conds = [];
 438                 foreach ( $namespaceConds as $namespace => $pageConds ) {
 439                         $conds[] = $db->makeList( [
 440                                 'wl_namespace = ' . $namespace,
 441                                 '(' . $db->makeList( $pageConds, LIST_OR ) . ')'
 442                         ], LIST_AND );
 443                 }
 444
 445                 if ( $missingTargets ) {
 446                         $lb = new LinkBatch( $missingTargets );
 447                         $conds[] = $lb->constructSet( 'wl', $db );
 448                 }
 449
 450                 return $db->makeList( $conds, LIST_OR );
 451         }
 452
 453         /**
 454          * Get an item (may be cached)
 455          *
 456          * @param User $user
 457          * @param LinkTarget $target
 458          *
 459          * @return WatchedItem|false
 460          */
 461         public function getWatchedItem( User $user, LinkTarget $target ) {
 462                 if ( $user->isAnon() ) {
 463                         return false;
 464                 }
 465
 466                 $cached = $this->getCached( $user, $target );
 467                 if ( $cached ) {
 468                         $this->stats->increment( 'WatchedItemStore.getWatchedItem.cached' );
 469                         return $cached;
 470                 }
 471                 $this->stats->increment( 'WatchedItemStore.getWatchedItem.load' );
 472                 return $this->loadWatchedItem( $user, $target );
 473         }
 474
 475         /**
 476          * Loads an item from the db
 477          *
 478          * @param User $user
 479          * @param LinkTarget $target
 480          *
 481          * @return WatchedItem|false
 482          */
 483         public function loadWatchedItem( User $user, LinkTarget $target ) {
 484                 // Only loggedin user can have a watchlist
 485                 if ( $user->isAnon() ) {
 486                         return false;
 487                 }
 488
 489                 $dbr = $this->getConnection( DB_SLAVE );
 490                 $row = $dbr->selectRow(
 491                         'watchlist',
 492                         'wl_notificationtimestamp',
 493                         $this->dbCond( $user, $target ),
 494                         __METHOD__
 495                 );
 496                 $this->reuseConnection( $dbr );
 497
 498                 if ( !$row ) {
 499                         return false;
 500                 }
 501
 502                 $item = new WatchedItem(
 503                         $user,
 504                         $target,
 505                         $row->wl_notificationtimestamp
 506                 );
 507                 $this->cache( $item );
 508
 509                 return $item;
 510         }
 511
 512         /**
 513          * @param User $user
 514          * @param array $options Allowed keys:
 515          *        'forWrite' => bool defaults to false
 516          *        'sort' => string optional sorting by namespace ID and title
 517          *                     one of the self::SORT_* constants
 518          *
 519          * @return WatchedItem[]
 520          */
 521         public function getWatchedItemsForUser( User $user, array $options = [] ) {
 522                 $options += [ 'forWrite' => false ];
 523
 524                 $dbOptions = [];
 525                 if ( array_key_exists( 'sort', $options ) ) {
 526                         Assert::parameter(
 527                                 ( in_array( $options['sort'], [ self::SORT_ASC, self::SORT_DESC ] ) ),
 528                                 '$options[\'sort\']',
 529                                 'must be SORT_ASC or SORT_DESC'
 530                         );
 531                         $dbOptions['ORDER BY'] = [
 532                                 "wl_namespace {$options['sort']}",
 533                                 "wl_title {$options['sort']}"
 534                         ];
 535                 }
 536                 $db = $this->getConnection( $options['forWrite'] ? DB_MASTER : DB_SLAVE );
 537
 538                 $res = $db->select(
 539                         'watchlist',
 540                         [ 'wl_namespace', 'wl_title', 'wl_notificationtimestamp' ],
 541                         [ 'wl_user' => $user->getId() ],
 542                         __METHOD__,
 543                         $dbOptions
 544                 );
 545                 $this->reuseConnection( $db );
 546
 547                 $watchedItems = [];
 548                 foreach ( $res as $row ) {
 549                         // todo these could all be cached at some point?
 550                         $watchedItems[] = new WatchedItem(
 551                                 $user,
 552                                 new TitleValue( (int)$row->wl_namespace, $row->wl_title ),
 553                                 $row->wl_notificationtimestamp
 554                         );
 555                 }
 556
 557                 return $watchedItems;
 558         }
 559
 560         /**
 561          * Must be called separately for Subject & Talk namespaces
 562          *
 563          * @param User $user
 564          * @param LinkTarget $target
 565          *
 566          * @return bool
 567          */
 568         public function isWatched( User $user, LinkTarget $target ) {
 569                 return (bool)$this->getWatchedItem( $user, $target );
 570         }
 571
 572         /**
 573          * @param User $user
 574          * @param LinkTarget[] $targets
 575          *
 576          * @return array multi-dimensional like $return[$namespaceId][$titleString] = $timestamp,
 577          *         where $timestamp is:
 578          *         - string|null value of wl_notificationtimestamp,
 579          *         - false if $target is not watched by $user.
 580          */
 581         public function getNotificationTimestampsBatch( User $user, array $targets ) {
 582                 $timestamps = [];
 583                 foreach ( $targets as $target ) {
 584                         $timestamps[$target->getNamespace()][$target->getDBkey()] = false;
 585                 }
 586
 587                 if ( $user->isAnon() ) {
 588                         return $timestamps;
 589                 }
 590
 591                 $targetsToLoad = [];
 592                 foreach ( $targets as $target ) {
 593                         $cachedItem = $this->getCached( $user, $target );
 594                         if ( $cachedItem ) {
 595                                 $timestamps[$target->getNamespace()][$target->getDBkey()] =
 596                                         $cachedItem->getNotificationTimestamp();
 597                         } else {
 598                                 $targetsToLoad[] = $target;
 599                         }
 600                 }
 601
 602                 if ( !$targetsToLoad ) {
 603                         return $timestamps;
 604                 }
 605
 606                 $dbr = $this->getConnection( DB_SLAVE );
 607
 608                 $lb = new LinkBatch( $targetsToLoad );
 609                 $res = $dbr->select(
 610                         'watchlist',
 611                         [ 'wl_namespace', 'wl_title', 'wl_notificationtimestamp' ],
 612                         [
 613                                 $lb->constructSet( 'wl', $dbr ),
 614                                 'wl_user' => $user->getId(),
 615                         ],
 616                         __METHOD__
 617                 );
 618                 $this->reuseConnection( $dbr );
 619
 620                 foreach ( $res as $row ) {
 621                         $timestamps[(int)$row->wl_namespace][$row->wl_title] = $row->wl_notificationtimestamp;
 622                 }
 623
 624                 return $timestamps;
 625         }
 626
 627         /**
 628          * Must be called separately for Subject & Talk namespaces
 629          *
 630          * @param User $user
 631          * @param LinkTarget $target
 632          */
 633         public function addWatch( User $user, LinkTarget $target ) {
 634                 $this->addWatchBatchForUser( $user, [ $target ] );
 635         }
 636
 637         /**
 638          * @param User $user
 639          * @param LinkTarget[] $targets
 640          *
 641          * @return bool success
 642          */
 643         public function addWatchBatchForUser( User $user, array $targets ) {
 644                 if ( $this->loadBalancer->getReadOnlyReason() !== false ) {
 645                         return false;
 646                 }
 647                 // Only loggedin user can have a watchlist
 648                 if ( $user->isAnon() ) {
 649                         return false;
 650                 }
 651
 652                 if ( !$targets ) {
 653                         return true;
 654                 }
 655
 656                 $rows = [];
 657                 foreach ( $targets as $target ) {
 658                         $rows[] = [
 659                                 'wl_user' => $user->getId(),
 660                                 'wl_namespace' => $target->getNamespace(),
 661                                 'wl_title' => $target->getDBkey(),
 662                                 'wl_notificationtimestamp' => null,
 663                         ];
 664                         $this->uncache( $user, $target );
 665                 }
 666
 667                 $dbw = $this->getConnection( DB_MASTER );
 668                 foreach ( array_chunk( $rows, 100 ) as $toInsert ) {
 669                         // Use INSERT IGNORE to avoid overwriting the notification timestamp
 670                         // if there's already an entry for this page
 671                         $dbw->insert( 'watchlist', $toInsert, __METHOD__, 'IGNORE' );
 672                 }
 673                 $this->reuseConnection( $dbw );
 674
 675                 return true;
 676         }
 677
 678         /**
 679          * Removes the an entry for the User watching the LinkTarget
 680          * Must be called separately for Subject & Talk namespaces
 681          *
 682          * @param User $user
 683          * @param LinkTarget $target
 684          *
 685          * @return bool success
 686          * @throws DBUnexpectedError
 687          * @throws MWException
 688          */
 689         public function removeWatch( User $user, LinkTarget $target ) {
 690                 // Only logged in user can have a watchlist
 691                 if ( $this->loadBalancer->getReadOnlyReason() !== false || $user->isAnon() ) {
 692                         return false;
 693                 }
 694
 695                 $this->uncache( $user, $target );
 696
 697                 $dbw = $this->getConnection( DB_MASTER );
 698                 $dbw->delete( 'watchlist',
 699                         [
 700                                 'wl_user' => $user->getId(),
 701                                 'wl_namespace' => $target->getNamespace(),
 702                                 'wl_title' => $target->getDBkey(),
 703                         ], __METHOD__
 704                 );
 705                 $success = (bool)$dbw->affectedRows();
 706                 $this->reuseConnection( $dbw );
 707
 708                 return $success;
 709         }
 710
 711         /**
 712          * @param User $editor The editor that triggered the update. Their notification
 713          *  timestamp will not be updated(they have already seen it)
 714          * @param LinkTarget $target The target to update timestamps for
 715          * @param string $timestamp Set the update timestamp to this value
 716          *
 717          * @return int[] Array of user IDs the timestamp has been updated for
 718          */
 719         public function updateNotificationTimestamp( User $editor, LinkTarget $target, $timestamp ) {
 720                 $dbw = $this->getConnection( DB_MASTER );
 721                 $res = $dbw->select( [ 'watchlist' ],
 722                         [ 'wl_user' ],
 723                         [
 724                                 'wl_user != ' . intval( $editor->getId() ),
 725                                 'wl_namespace' => $target->getNamespace(),
 726                                 'wl_title' => $target->getDBkey(),
 727                                 'wl_notificationtimestamp IS NULL',
 728                         ], __METHOD__
 729                 );
 730
 731                 $watchers = [];
 732                 foreach ( $res as $row ) {
 733                         $watchers[] = intval( $row->wl_user );
 734                 }
 735
 736                 if ( $watchers ) {
 737                         // Update wl_notificationtimestamp for all watching users except the editor
 738                         $fname = __METHOD__;
 739                         $dbw->onTransactionIdle(
 740                                 function () use ( $dbw, $timestamp, $watchers, $target, $fname ) {
 741                                         $dbw->update( 'watchlist',
 742                                                 [ /* SET */
 743                                                         'wl_notificationtimestamp' => $dbw->timestamp( $timestamp )
 744                                                 ], [ /* WHERE */
 745                                                         'wl_user' => $watchers,
 746                                                         'wl_namespace' => $target->getNamespace(),
 747                                                         'wl_title' => $target->getDBkey(),
 748                                                 ], $fname
 749                                         );
 750                                         $this->uncacheLinkTarget( $target );
 751                                 }
 752                         );
 753                 }
 754
 755                 $this->reuseConnection( $dbw );
 756
 757                 return $watchers;
 758         }
 759
 760         /**
 761          * Reset the notification timestamp of this entry
 762          *
 763          * @param User $user
 764          * @param Title $title
 765          * @param string $force Whether to force the write query to be executed even if the
 766          *    page is not watched or the notification timestamp is already NULL.
 767          *    'force' in order to force
 768          * @param int $oldid The revision id being viewed. If not given or 0, latest revision is assumed.
 769          *
 770          * @return bool success
 771          */
 772         public function resetNotificationTimestamp( User $user, Title $title, $force = '', $oldid = 0 ) {
 773                 // Only loggedin user can have a watchlist
 774                 if ( $this->loadBalancer->getReadOnlyReason() !== false || $user->isAnon() ) {
 775                         return false;
 776                 }
 777
 778                 $item = null;
 779                 if ( $force != 'force' ) {
 780                         $item = $this->loadWatchedItem( $user, $title );
 781                         if ( !$item || $item->getNotificationTimestamp() === null ) {
 782                                 return false;
 783                         }
 784                 }
 785
 786                 // If the page is watched by the user (or may be watched), update the timestamp
 787                 $job = new ActivityUpdateJob(
 788                         $title,
 789                         [
 790                                 'type'      => 'updateWatchlistNotification',
 791                                 'userid'    => $user->getId(),
 792                                 'notifTime' => $this->getNotificationTimestamp( $user, $title, $item, $force, $oldid ),
 793                                 'curTime'   => time()
 794                         ]
 795                 );
 796
 797                 // Try to run this post-send
 798                 // Calls DeferredUpdates::addCallableUpdate in normal operation
 799                 call_user_func(
 800                         $this->deferredUpdatesAddCallableUpdateCallback,
 801                         function() use ( $job ) {
 802                                 $job->run();
 803                         }
 804                 );
 805
 806                 $this->uncache( $user, $title );
 807
 808                 return true;
 809         }
 810
 811         private function getNotificationTimestamp( User $user, Title $title, $item, $force, $oldid ) {
 812                 if ( !$oldid ) {
 813                         // No oldid given, assuming latest revision; clear the timestamp.
 814                         return null;
 815                 }
 816
 817                 if ( !$title->getNextRevisionID( $oldid ) ) {
 818                         // Oldid given and is the latest revision for this title; clear the timestamp.
 819                         return null;
 820                 }
 821
 822                 if ( $item === null ) {
 823                         $item = $this->loadWatchedItem( $user, $title );
 824                 }
 825
 826                 if ( !$item ) {
 827                         // This can only happen if $force is enabled.
 828                         return null;
 829                 }
 830
 831                 // Oldid given and isn't the latest; update the timestamp.
 832                 // This will result in no further notification emails being sent!
 833                 // Calls Revision::getTimestampFromId in normal operation
 834                 $notificationTimestamp = call_user_func(
 835                         $this->revisionGetTimestampFromIdCallback,
 836                         $title,
 837                         $oldid
 838                 );
 839
 840                 // We need to go one second to the future because of various strict comparisons
 841                 // throughout the codebase
 842                 $ts = new MWTimestamp( $notificationTimestamp );
 843                 $ts->timestamp->add( new DateInterval( 'PT1S' ) );
 844                 $notificationTimestamp = $ts->getTimestamp( TS_MW );
 845
 846                 if ( $notificationTimestamp < $item->getNotificationTimestamp() ) {
 847                         if ( $force != 'force' ) {
 848                                 return false;
 849                         } else {
 850                                 // This is a little silly…
 851                                 return $item->getNotificationTimestamp();
 852                         }
 853                 }
 854
 855                 return $notificationTimestamp;
 856         }
 857
 858         /**
 859          * @param User $user
 860          * @param int $unreadLimit
 861          *
 862          * @return int|bool The number of unread notifications
 863          *                  true if greater than or equal to $unreadLimit
 864          */
 865         public function countUnreadNotifications( User $user, $unreadLimit = null ) {
 866                 $queryOptions = [];
 867                 if ( $unreadLimit !== null ) {
 868                         $unreadLimit = (int)$unreadLimit;
 869                         $queryOptions['LIMIT'] = $unreadLimit;
 870                 }
 871
 872                 $dbr = $this->getConnection( DB_SLAVE );
 873                 $rowCount = $dbr->selectRowCount(
 874                         'watchlist',
 875                         '1',
 876                         [
 877                                 'wl_user' => $user->getId(),
 878                                 'wl_notificationtimestamp IS NOT NULL',
 879                         ],
 880                         __METHOD__,
 881                         $queryOptions
 882                 );
 883                 $this->reuseConnection( $dbr );
 884
 885                 if ( !isset( $unreadLimit ) ) {
 886                         return $rowCount;
 887                 }
 888
 889                 if ( $rowCount >= $unreadLimit ) {
 890                         return true;
 891                 }
 892
 893                 return $rowCount;
 894         }
 895
 896         /**
 897          * Check if the given title already is watched by the user, and if so
 898          * add a watch for the new title.
 899          *
 900          * To be used for page renames and such.
 901          *
 902          * @param LinkTarget $oldTarget
 903          * @param LinkTarget $newTarget
 904          */
 905         public function duplicateAllAssociatedEntries( LinkTarget $oldTarget, LinkTarget $newTarget ) {
 906                 if ( !$oldTarget instanceof Title ) {
 907                         $oldTarget = Title::newFromLinkTarget( $oldTarget );
 908                 }
 909                 if ( !$newTarget instanceof Title ) {
 910                         $newTarget = Title::newFromLinkTarget( $newTarget );
 911                 }
 912
 913                 $this->duplicateEntry( $oldTarget->getSubjectPage(), $newTarget->getSubjectPage() );
 914                 $this->duplicateEntry( $oldTarget->getTalkPage(), $newTarget->getTalkPage() );
 915         }
 916
 917         /**
 918          * Check if the given title already is watched by the user, and if so
 919          * add a watch for the new title.
 920          *
 921          * To be used for page renames and such.
 922          * This must be called separately for Subject and Talk pages
 923          *
 924          * @param LinkTarget $oldTarget
 925          * @param LinkTarget $newTarget
 926          */
 927         public function duplicateEntry( LinkTarget $oldTarget, LinkTarget $newTarget ) {
 928                 $dbw = $this->getConnection( DB_MASTER );
 929
 930                 $result = $dbw->select(
 931                         'watchlist',
 932                         [ 'wl_user', 'wl_notificationtimestamp' ],
 933                         [
 934                                 'wl_namespace' => $oldTarget->getNamespace(),
 935                                 'wl_title' => $oldTarget->getDBkey(),
 936                         ],
 937                         __METHOD__,
 938                         [ 'FOR UPDATE' ]
 939                 );
 940
 941                 $newNamespace = $newTarget->getNamespace();
 942                 $newDBkey = $newTarget->getDBkey();
 943
 944                 # Construct array to replace into the watchlist
 945                 $values = [];
 946                 foreach ( $result as $row ) {
 947                         $values[] = [
 948                                 'wl_user' => $row->wl_user,
 949                                 'wl_namespace' => $newNamespace,
 950                                 'wl_title' => $newDBkey,
 951                                 'wl_notificationtimestamp' => $row->wl_notificationtimestamp,
 952                         ];
 953                 }
 954
 955                 if ( !empty( $values ) ) {
 956                         # Perform replace
 957                         # Note that multi-row replace is very efficient for MySQL but may be inefficient for
 958                         # some other DBMSes, mostly due to poor simulation by us
 959                         $dbw->replace(
 960                                 'watchlist',
 961                                 [ [ 'wl_user', 'wl_namespace', 'wl_title' ] ],
 962                                 $values,
 963                                 __METHOD__
 964                         );
 965                 }
 966
 967                 $this->reuseConnection( $dbw );
 968         }
 969
 970 }