WordPress at a glance
function is not described

_count_posts_cache_key() WP 3.9.0

Return the cache key for wp_count_posts() based on the passed arguments.

No Hooks.

Return

String. The cache key.

Usage

_count_posts_cache_key( $type, $perm );
$type(string)
Post type to retrieve count Default 'post'.
Default: 'post'
$perm(string)
'readable' or empty.
Default: ''

Code of count posts cache key: wp-includes/post.php VER 5.1.1

<?php
function _count_posts_cache_key( $type = 'post', $perm = '' ) {
	$cache_key = 'posts-' . $type;
	if ( 'readable' == $perm && is_user_logged_in() ) {
		$post_type_object = get_post_type_object( $type );
		if ( $post_type_object && ! current_user_can( $post_type_object->cap->read_private_posts ) ) {
			$cache_key .= '_' . $perm . '_' . get_current_user_id();
		}
	}
	return $cache_key;
}