lfu_update

lfu_update.rs

    fn update_freq_node(&mut self, key: &'a str) {
        let entry =  self.by_key.get_mut(key).unwrap();

        // get the freq node
        let freq_node = self.freq_node.get_mut(&entry.count).unwrap();
                    
        // once it have been access
        // we need to remove the key in this current node
        freq_node.remove(key);

        if entry.count == self.least_freq_node && freq_node.is_empty() {
            self.least_freq_node += 1;
        }

        // add to the next freq node
        self.freq_node.entry(entry.count+1).or_default().insert(key);
            
        // increase the access account
        entry.inc();
    }