Move code to load User data from cache out of loadFromId

This way, outside code can load data from cache only if present. E.g. when data
for a lot of users is needed, it'd be preferable to batch-load all that is not
yet in cache.

Since there's currently no way to check for data in cache, one would have to
load all User objects separately (which may result in lots of DB queries if
nothing is in cache) or batch-load all of them (which may result in few DB
queries, but ones that may not be needed if all data is already in cache)

Change-Id: Ia22d04744760c3b6f3264786434e218b8aa88d53

diff --git a/includes/User.php b/includes/User.php
index 635b1e9..9897013 100644 (file)
--- a/includes/User.php
+++ b/includes/User.php
@@ -357,21 +357,14 @@ class User implements IDBAccessObject {
         * @return bool False if the ID does not exist, true otherwise
         */
        public function loadFromId() {
-               global $wgMemc;
                if ( $this->mId == 0 ) {
                        $this->loadDefaults();
                        return false;
                }
 
                // Try cache
-               $key = wfMemcKey( 'user', 'id', $this->mId );
-               $data = $wgMemc->get( $key );
-               if ( !is_array( $data ) || $data['mVersion'] != self::VERSION ) {
-                       // Object is expired, load from DB
-                       $data = false;
-               }
-
-               if ( !$data ) {
+               $cache = $this->loadFromCache();
+               if ( !$cache ) {
                        wfDebug( "User: cache miss for user {$this->mId}\n" );
                        // Load from DB
                        if ( !$this->loadFromDatabase() ) {
@@ -379,12 +372,6 @@ class User implements IDBAccessObject {
                                return false;
                        }
                        $this->saveToCache();
-               } else {
-                       wfDebug( "User: got user {$this->mId} from cache\n" );
-                       // Restore from cache
-                       foreach ( self::$mCacheVars as $name ) {
-                               $this->$name = $data[$name];
-                       }
                }
 
                $this->mLoadedItems = true;
@@ -392,6 +379,37 @@ class User implements IDBAccessObject {
                return true;
        }
 
+       /**
+        * Load user data from shared cache, given mId has already been set.
+        *
+        * @return bool false if the ID does not exist or data is invalid, true otherwise
+        * @since 1.25
+        */
+       public function loadFromCache() {
+               global $wgMemc;
+
+               if ( $this->mId == 0 ) {
+                       $this->loadDefaults();
+                       return false;
+               }
+
+               $key = wfMemcKey( 'user', 'id', $this->mId );
+               $data = $wgMemc->get( $key );
+               if ( !is_array( $data ) || $data['mVersion'] < self::VERSION ) {
+                       // Object is expired
+                       return false;
+               }
+
+               wfDebug( "User: got user {$this->mId} from cache\n" );
+
+               // Restore from cache
+               foreach ( self::$mCacheVars as $name ) {
+                       $this->$name = $data[$name];
+               }
+
+               return true;
+       }
+
        /**
         * Save user data to the shared cache
         */