Struct ResponseCache 

pub struct ResponseCache { /* private fields */ }

Response cache: LRU + TTL + in-flight deduplication.

Cheaply Clone-able — all clones share the same underlying Arc state.

A TTL of Duration::ZERO disables the cache entirely — get always returns None and insert is a no-op.

Implementations

impl ResponseCache

pub fn disabled() -> Self

Create a disabled cache (TTL = Duration::ZERO).

All operations are no-ops. No memory is allocated for entries.

pub fn new(ttl: Duration, capacity: usize) -> Self

Create an enabled cache with the given ttl and LRU capacity.

Entries older than ttl are treated as expired on next access. When the cache is full the least-recently-used entry is evicted.

pub fn is_enabled(&self) -> bool

true when the cache is active (TTL > 0).

pub fn ttl(&self) -> Duration

Current TTL setting.

pub async fn get(&self, key: &str) -> Option<ServerStatus>

Try to return a non-expired cached ServerStatus for key.

Returns None when:

• the cache is disabled,
• no entry exists for key, or
• the entry has expired (age ≥ TTL).

On a hit, the returned status has cached = true and latency = 0.0.

pub async fn insert(&self, key: String, status: ServerStatus)

Store a successful ServerStatus under key and broadcast it to any tasks waiting on the in-flight channel for this key.

If the cache is disabled this is a no-op (but the broadcast still fires if an in-flight entry exists, releasing any waiting subscribers).

pub async fn insert_error(&self, key: &str, err: &McError)

Notify in-flight subscribers of a failure for key, then free the slot.

The error message is broadcast as a String so subscribers can surface a meaningful error without cloning the original McError.

pub async fn join_or_register( &self, key: &str, ) -> Option<Receiver<Result<ServerStatus, String>>>

Attempt to join an existing in-flight request for key, or register this task as the designated pinger.

Returns:

• Some(receiver) — another task is already pinging; wait on this channel for the result.
• None — this task is first; it must call insert or insert_error when the ping completes.

Always returns None when the cache is disabled.

pub async fn clear(&self)

Clear all cached entries and all in-flight registrations.

pub async fn len(&self) -> usize

Number of entries currently in the LRU (includes expired entries that have not yet been accessed and evicted).

Trait Implementations

impl Clone for ResponseCache

fn clone(&self) -> ResponseCache

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.