pub fn insert(&self, key: K, value: V) {
        let latency = self.metrics.latency[&Method::Insert].start();
        let Some(cache) = self.cache.as_ref() else {
            return;
        };
        // ^ We intentionally don't report metrics if there's no real cache.
        cache.insert(key, value);

        latency.observe();
        self.report_size();
    }
Pushes an entry and performs LRU cache operations.
core/lib/state/src/cache/lru_cache.rs