Made user preferences load from the master by default

* Warn when saving slave-loaded data in saveSettings()
* Respect the loading $flags for preferences/groups
* Fixed use of flags in addToDatabase()
* Made loadFromCache() protected to make this mess easier
  to reason about (no callers found)
* Added some doc comments

Bug: T92232
Change-Id: Ic1dd66063cc2f98fc03861df1c523981f846a0be

diff --git a/includes/User.php b/includes/User.php
index 97eaa5c..4d19cf6 100644 (file)
--- a/includes/User.php
+++ b/includes/User.php
@@ -295,6 +295,9 @@ class User implements IDBAccessObject {
        /** @var array */
        private $mWatchedItems = array();
 
+       /** @var integer User::READ_* constant bitfield used to load data */
+       protected $queryFlagsUsed = self::READ_NORMAL;
+
        public static $idCacheByName = array();
 
        /**
@@ -330,6 +333,7 @@ class User implements IDBAccessObject {
 
                // Set it now to avoid infinite recursion in accessors
                $this->mLoadedItems = true;
+               $this->queryFlagsUsed = $flags;
 
                switch ( $this->mFrom ) {
                        case 'defaults':
@@ -390,6 +394,7 @@ class User implements IDBAccessObject {
                }
 
                $this->mLoadedItems = true;
+               $this->queryFlagsUsed = $flags;
 
                return true;
        }
@@ -400,7 +405,7 @@ class User implements IDBAccessObject {
         * @return bool false if the ID does not exist or data is invalid, true otherwise
         * @since 1.25
         */
-       public function loadFromCache() {
+       protected function loadFromCache() {
                global $wgMemc;
 
                if ( $this->mId == 0 ) {
@@ -427,22 +432,35 @@ class User implements IDBAccessObject {
 
        /**
         * Save user data to the shared cache
+        *
+        * This method should not be called outside the User class
         */
        public function saveToCache() {
+               global $wgMemc;
+
                $this->load();
                $this->loadGroups();
                $this->loadOptions();
+
                if ( $this->isAnon() ) {
                        // Anonymous users are uncached
                        return;
                }
+
+               // The cache needs good consistency due to its high TTL, so the user
+               // should have been loaded from the master to avoid lag amplification.
+               if ( !( $this->queryFlagsUsed & self::READ_LATEST ) ) {
+                       wfWarn( "Cannot save slave-loaded User object data to cache." );
+                       return;
+               }
+
                $data = array();
                foreach ( self::$mCacheVars as $name ) {
                        $data[$name] = $this->$name;
                }
                $data['mVersion'] = self::VERSION;
                $key = wfMemcKey( 'user', 'id', $this->mId );
-               global $wgMemc;
+
                $wgMemc->set( $key, $data );
        }
 
@@ -1057,7 +1075,6 @@ class User implements IDBAccessObject {
                $this->mGroups = array();
 
                Hooks::run( 'UserLoadDefaults', array( $this, $name ) );
-
        }
 
        /**
@@ -1201,6 +1218,7 @@ class User implements IDBAccessObject {
                                : array()
                );
 
+               $this->queryFlagsUsed = $flags;
                Hooks::run( 'UserLoadFromDatabase', array( $this, &$s ) );
 
                if ( $s !== false ) {
@@ -1338,7 +1356,9 @@ class User implements IDBAccessObject {
         */
        private function loadGroups() {
                if ( is_null( $this->mGroups ) ) {
-                       $dbr = wfGetDB( DB_MASTER );
+                       $dbr = ( $this->queryFlagsUsed & self::READ_LATEST )
+                               ? wfGetDB( DB_MASTER )
+                               : wfGetDB( DB_SLAVE );
                        $res = $dbr->select( 'user_groups',
                                array( 'ug_group' ),
                                array( 'ug_user' => $this->mId ),
@@ -1362,11 +1382,11 @@ class User implements IDBAccessObject {
        private function loadPasswords() {
                if ( $this->getId() !== 0 && ( $this->mPassword === null || $this->mNewpassword === null ) ) {
                        $this->loadFromRow( wfGetDB( DB_MASTER )->selectRow(
-                                       'user',
-                                       array( 'user_password', 'user_newpassword', 'user_newpass_time', 'user_password_expires' ),
-                                       array( 'user_id' => $this->getId() ),
-                                       __METHOD__
-                               ) );
+                               'user',
+                               array( 'user_password', 'user_newpassword', 'user_newpass_time', 'user_password_expires' ),
+                               array( 'user_id' => $this->getId() ),
+                               __METHOD__
+                       ) );
                }
        }
 
@@ -3021,6 +3041,8 @@ class User implements IDBAccessObject {
         * @return bool
         */
        public function addGroup( $group ) {
+               $this->load();
+
                if ( !Hooks::run( 'UserAddGroup', array( $this, &$group ) ) ) {
                        return false;
                }
@@ -3510,12 +3532,18 @@ class User implements IDBAccessObject {
                $this->load();
                $this->loadPasswords();
                if ( wfReadOnly() ) {
-                       return;
+                       return; // @TODO: caller should deal with this instead!
                }
                if ( 0 == $this->mId ) {
                        return;
                }
 
+               // This method is for updating existing users, so the user should
+               // have been loaded from the master to begin with to avoid problems.
+               if ( !( $this->queryFlagsUsed & self::READ_LATEST ) ) {
+                       wfWarn( "Attempting to save slave-loaded User object data." );
+               }
+
                $this->mTouched = self::newTouchedTimestamp();
                if ( !$wgAuth->allowSetLocalPassword() ) {
                        $this->mPassword = self::getPasswordFactory()->newFromCiphertext( null );
@@ -3691,7 +3719,7 @@ class User implements IDBAccessObject {
                                // using CentralAuth. It's should be OK to commit and break the snapshot.
                                $dbw->commit( __METHOD__, 'flush' );
                                $options = array();
-                               $flags = 0;
+                               $flags = self::READ_LATEST;
                        }
                        $this->mId = $dbw->selectField( 'user', 'user_id',
                                array( 'user_name' => $this->mName ), __METHOD__, $options );
@@ -4862,7 +4890,9 @@ class User implements IDBAccessObject {
                        if ( !is_array( $data ) ) {
                                wfDebug( "User: loading options for user " . $this->getId() . " from database.\n" );
                                // Load from database
-                               $dbr = wfGetDB( DB_SLAVE );
+                               $dbr = ( $this->queryFlagsUsed & self::READ_LATEST )
+                                       ? wfGetDB( DB_MASTER )
+                                       : wfGetDB( DB_SLAVE );
 
                                $res = $dbr->select(
                                        'user_properties',