Use db-replicated objectcache for storing last seen time

So we're not abusing user preferences for the last seen time.
EchoSeenTime is a small wrapper around ObjectCache that handles the
fallback to user preferences during the transition.

All JavaScript code now needs to use mw.config.get('wgEchoSeenTime').

Bug: T95839
Change-Id: Ia45ba5e30eb4564250539d04d5886d2598ebd49a

Hooks.php

@@ -638,7 +638,8 @@ class EchoHooks {
 		$msgNotificationTimestamp = $notifUser->getLastUnreadMessageTime();
 		$alertNotificationTimestamp = $notifUser->getLastUnreadAlertTime();
 
-		$seenTime = $user->getOption( 'echo-seen-time' );
+		$seenTime = EchoSeenTime::newFromUser( $user )->getTime();
+		$sk->getOutput()->addJsConfigVars( 'wgEchoSeenTime', $seenTime );
 
 		$msgText = EchoNotificationController::formatNotificationCount( $msgCount );
 		$alertText = EchoNotificationController::formatNotificationCount( $alertCount );

autoload.php

@@ -71,6 +71,7 @@ $wgAutoloadClasses += array(
 	'EchoPageLinkFormatter' => __DIR__ . '/includes/formatters/PageLinkFormatter.php',
 	'EchoRevisionLocalCache' => __DIR__ . '/includes/cache/RevisionLocalCache.php',
 	'EchoRowUpdateGenerator' => __DIR__ . '/includes/BatchRowUpdate.php',
+	'EchoSeenTime' => __DIR__ . '/includes/SeenTime.php',
 	'EchoSuppressionRowUpdateGenerator' => __DIR__ . '/includes/schemaUpdate.php',
 	'EchoTalkPageFunctionalTest' => __DIR__ . '/tests/phpunit/TalkPageFunctionalTest.php',
 	'EchoTargetPage' => __DIR__ . '/includes/model/TargetPage.php',

includes/SeenTime.php

@@ -0,0 +1,59 @@
+<?php
+
+/**
+ * A small wrapper around ObjectCache to manage
+ * storing the last time a user has seen notifications
+ */
+class EchoSeenTime {
+
+	/**
+	 * @var User
+	 */
+	private $user;
+
+	/**
+	 * @var string
+	 */
+	private $key;
+
+	/**
+	 * @var BagOStuff
+	 */
+	private $cache;
+
+	/**
+	 * @param User $user A logged in user
+	 */
+	private function __construct( User $user ) {
+		$this->user = $user;
+		$this->key = wfMemcKey( 'echo', 'seen', 'time', $user->getId() );
+		$this->cache = ObjectCache::getInstance( 'db-replicated' );
+	}
+
+	/**
+	 * @param User $user
+	 * @return EchoSeenTime
+	 */
+	public static function newFromUser( User $user ) {
+		return new self( $user );
+	}
+
+	/**
+	 * @param int $flags BagOStuff::READ_LATEST to use the master
+	 * @return string|bool false if no stored time
+	 */
+	public function getTime( $flags = 0 ) {
+		$cas = 0; // Unused, but we have to pass something by reference
+		$data = $this->cache->get( $this->key, $cas, $flags );
+		if ( $data === false ) {
+			// Check if the user still has it set in their preferences
+			$data = $this->user->getOption( 'echo-seen-time', false );
+		}
+
+		return $data;
+	}
+
+	public function setTime( $time ) {
+		return $this->cache->set( $this->key, $time );
+	}
+}

includes/api/ApiEchoMarkSeen.php

@@ -11,14 +11,9 @@ class ApiEchoMarkSeen extends ApiBase {
 			$this->dieUsage( 'Login is required', 'login-required' );
 		}
 
-		// Load from the master to reduce CAS errors from high update frequency
-		$u = User::newFromId( $user->getId() );
-		$u->load( User::READ_LATEST );
-
 		$timestamp = wfTimestamp( TS_MW );
-		// @TODO: do not abuse user preferences for "last seen"
-		$u->setOption( 'echo-seen-time', $timestamp );
-		$u->saveSettings();
+		$seenTime = EchoSeenTime::newFromUser( $user );
+		$seenTime->setTime( $timestamp );
 
 		$this->getResult()->addValue( 'query', $this->getModuleName(), array(
 			'result' => 'success',

includes/special/SpecialNotifications.php

@@ -71,7 +71,8 @@ class SpecialNotifications extends SpecialPage {
 		$dateHeader = '';
 		$notices = '';
 		$unread = array();
-		$seenTime = $user->getOption( 'echo-seen-time' );
+		$echoSeenTime = EchoSeenTime::newFromUser( $user );
+		$seenTime = $echoSeenTime->getTime();
 		foreach ( $notif as $row ) {
 			$class = 'mw-echo-notification';
 
@@ -141,8 +142,7 @@ class SpecialNotifications extends SpecialPage {
 
 		// Record time notifications have been seen
 		$timestamp = wfTimestamp( TS_MW );
-		$user->setOption( 'echo-seen-time', $timestamp );
-		$user->saveSettings();
+		$echoSeenTime->setTime( $timestamp );
 	}
 
 	/**

modules/special/ext.echo.special.js

@@ -61,7 +61,7 @@
 		loadMore: function () {
 			var notifications, data, container, $li,
 				api = new mw.Api( { ajax: { cache: false } } ),
-				seenTime = mw.user.options.get( 'echo-seen-time' ),
+				seenTime = mw.config.get( 'wgEchoSeenTime' ),
 				that = this,
 				unread = [],
 				apiData = {

modules/viewmodel/mw.echo.dm.NotificationsModel.js

@@ -27,7 +27,7 @@
 		this.api = new mw.Api( { ajax: { cache: false } } );
 		this.fetchNotificationsPromise = null;
 
-		this.seenTime = mw.user.options.get( 'echo-seen-time' );
+		this.seenTime = mw.config.get( 'wgEchoSeenTime' );
 
 		// Store references to unseen and unread notifications
 		this.unseenNotifications = new mw.echo.dm.NotificationList();
@@ -189,9 +189,9 @@
 				items = model.unseenNotifications.getItems(),
 				time = data.query.echomarkseen.timestamp;
 
-			// update echo-seen-time value in JS (where it wouldn't
+			// update wgEchoSeenTime value in JS (where it wouldn't
 			// otherwise propagate until page reload)
-			mw.user.options.set( 'echo-seen-time', time );
+			mw.config.set( 'wgEchoSeenTime', time );
 			model.setSeenTime( time );
 
 			// Update the notifications seen status