You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: top_n.rs
    path of file: ./repos/risingwave/src/stream/src/common/cache/state_cache
    
    the code of the file until where you have to start completion: // Copyright 2024 RisingWave Labs
//
// Licensed under t
    
    fn delete_synced(&mut self, key: &K) -> Option<V> {
        let old_val = self.cache.remove(key);
        self.table_row_count = self.table_row_count.map(|n| n - 1);
        if self.cache.is_empty() && !self.row_count_matched() {
            // The cache becomes empty, but there're still rows in the table, so mark it as not
            // synced.
            self.synced = false;
        }
        old_val
    }