Deletes a key. Returns true when a key was removed. `DEL` returns an integer count. Non-zero maps to true.

Evicts entries until within the configured byte budget. Scans shards in round-robin order to avoid concentrating evictions.

Evicts a single LRU entry from a shard. Returns the reclaimed byte size for global accounting.

Executes a RESP command and returns the parsed response.

Fetches a value by key. Returns `Ok(None)` when the key is missing. The server response is expected to be a bulk string or null bulk string.

Handles a single TCP client connection with shared server metrics.

Inserts a new node and returns its slot index. Reuses a free slot if available to reduce allocations under churn.

Returns true if entry has expired relative to current time

Normalizes shard counts to a power of two for fast masking. This keeps shard selection branch-free and avoids modulo operations.

Pops stale heap heads until a live expired entry is found or the next deadline is still in the future.

Removes and returns the least-recently used node size. Used by the eviction logic when over capacity.

Sets a value for a key without expiration. Uses RESP2 `SET key value` and expects a simple string response.

Sets a value and attaches an expiration in seconds. Uses RESP2 `SET key value EX seconds`. TTL seconds are encoded without heap allocations.

Hashes a key to its owning shard index. Uses the same hash state as the shard map to keep distribution uniform.

Returns entry size in bytes (key + value + metadata)