WordPress at a glance
function is not described

update_user_caches() WP 3.0.0

Update all user caches

No Hooks.

Return

true/false/null. Returns false on failure.

Usage

update_user_caches( $user );
$user(WP_User) (required)
User object to be cached

Changelog

Since 3.0.0 Introduced.

Code of update user caches: wp-includes/user.php WP 5.2.2

<?php
function update_user_caches( $user ) {
	if ( $user instanceof WP_User ) {
		if ( ! $user->exists() ) {
			return false;
		}

		$user = $user->data;
	}

	wp_cache_add( $user->ID, $user, 'users' );
	wp_cache_add( $user->user_login, $user->ID, 'userlogins' );
	wp_cache_add( $user->user_email, $user->ID, 'useremail' );
	wp_cache_add( $user->user_nicename, $user->ID, 'userslugs' );
}