Cache configurations should be runtime-configurable rather than hardcoded, with support for dynamic resizing when configuration changes. This practice improves adaptability to varying workloads and environments without requiring service restarts.
When implementing caches:
// Do this: #[derive(Debug, Clone, Deserialize)] pub struct TenantConfig { pub relsize_snapshot_cache_capacity: usize, // other config parameters… }
2. Implement handlers to resize caches when configuration changes:
```rust
fn tenant_conf_updated(&self, new_conf: TenantConfig) {
// Update the cache capacity when config changes
let mut cache = self.rel_size_cache.write().unwrap();
cache.resize_capacity(new_conf.relsize_snapshot_cache_capacity);
}
fn insert(&mut self, key: K, value: V) {
if self.cache.contains_key(&key) {
// Handle existing entry - consider evicting old entry,
// updating statistics, or queueing for cleanup
self.deletion_queue.send(key.clone());
}
self.cache.insert(key, value);
}
This approach ensures that caches can be tuned for optimal performance based on actual usage patterns without service disruptions, and properly manages the lifecycle of cached entries.