+ /**
+ * Update the "touched" timestamp for the user
+ *
+ * This is useful on various login/logout events when making sure that
+ * a browser or proxy that has multiple tenants does not suffer cache
+ * pollution where the new user sees the old users content. The value
+ * of getTouched() is checked when determining 304 vs 200 responses.
+ * Unlike invalidateCache(), this preserves the User object cache and
+ * avoids database writes.
+ *
+ * @since 1.25
+ */
+ public function touch() {
+ global $wgMemc;
+
+ $this->load();
+
+ if ( $this->mId ) {
+ $key = wfMemcKey( 'user-quicktouched', 'id', $this->mId );
+ $timestamp = self::newTouchedTimestamp();
+ $wgMemc->set( $key, $timestamp );
+ $this->mQuickTouched = $timestamp;
+ }
+ }
+