wpdb::__construct()
Method: Connects to the database server and selects a database.
Source: wp-includes/class-wpdb.php:768
wpdb::__destruct()
Method: PHP5 style destructor and will run when database object is destroyed.
Source: wp-includes/wp-db.php:608
WP_Object_Cache::__construct()
Method: Sets up object properties; PHP 5 style constructor.
Source: wp-includes/class-wp-object-cache.php:80
WP_Object_Cache::__destruct()
Method: Saves the object cache before object is completely destroyed.
Source: wp-includes/cache.php:729