(PECL mongo >= 1.0.0)
    Caused by a query timing out.  You can set the length of time to wait before
    this exception is thrown by calling 
    MongoCursor::timeout() on the cursor or setting
    MongoCursor::$timeout.  The static variable is useful for
    queries such as database commands and 
    MongoCollection::findOne(), both of which implicitly use 
    cursors.