Updating current session data?

I’m trying to add custom data to user sessions and I’m having some trouble.

The first issue is I can’t figure out how to return 2 variables which are included in the original filter. As a result I’m getting this error:

Missing argument 2 for add_last_activity_to_session()

// on user login, add last_activity column
add_filter('attach_session_information', 'add_last_activity_to_session');
function add_last_activity_to_session( $session , $user_id ) {
    $session['last_activity'] = time();

    return $session;
}

The attach_session_information hook has 2 parameters: $session and $user_id. I’m guessing the error is happening as my function is only returning the session. How would I fix this?

The second issue is how can I update the current session? I’m getting the error:

Call to protected method WP_Session_Tokens::update_session() from context

I think it’s from calling WP_Session_Tokens::update_session() but I don’t know how to avoid it. Is there a way of calling a private core WP function from functions.php

/*
* Update last activity for a user
*/
add_action( 'init', 'update_session_activity' );
function update_session_activity() {
    if ( !is_user_logged_in() ) {
        return false;
    }

    $sessions = WP_Session_Tokens::get_instance( get_current_user_id() );
    $token = wp_get_session_token();
    $current_user_session = $sessions->get( $token );

    $date_format = get_option( 'date_format', 'F j, Y' ) . ' @ ' . get_option( 'time_format', 'g:i A' );

    $current_user_session['last_activity'] = time();

    WP_Session_Tokens::update_session($token, $current_user_session);

    echo esc_html( date_i18n( $date_format, $current_user_session['last_activity'] ) );
}