get_usermeta() WordPress Function

function get_usermeta( $user_id, $meta_key = '' ) {
	_deprecated_function( __FUNCTION__, '3.0.0', 'get_user_meta()' );
	global $wpdb;
	$user_id = (int) $user_id;

	if ( !$user_id )
		return false;

	if ( !empty($meta_key) ) {
		$meta_key = preg_replace('|[^a-z0-9_]|i', '', $meta_key);
		$user = wp_cache_get($user_id, 'users');
		// Check the cached user object.
		if ( false !== $user && isset($user->$meta_key) )
			$metas = array($user->$meta_key);
		else
			$metas = $wpdb->get_col( $wpdb->prepare("SELECT meta_value FROM $wpdb->usermeta WHERE user_id = %d AND meta_key = %s", $user_id, $meta_key) );
	} else {
		$metas = $wpdb->get_col( $wpdb->prepare("SELECT meta_value FROM $wpdb->usermeta WHERE user_id = %d", $user_id) );
	}

	if ( empty($metas) ) {
		if ( empty($meta_key) )
			return array();
		else
			return '';
	}

	$metas = array_map('maybe_unserialize', $metas);

	if ( count($metas) == 1 )
		return $metas[0];
	else
		return $metas;
}