Struct TtlCache 

pub struct TtlCache<K, V> { /* private fields */ }

A cache that automatically expires entries after a configurable TTL.

This is useful for tracking order lifetimes in rate limiting, where orders cancelled within certain time windows incur different penalties.

Implementations

impl<K, V> TtlCache<K, V>

where K: Hash + Eq,

pub fn new(ttl: Duration) -> Self

Create a new TTL cache with the specified time-to-live duration.

Entries will be considered expired after this duration.

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

Create a new TTL cache with a specific initial capacity.

pub fn insert(&mut self, key: K, value: V)

Insert a key-value pair into the cache.

The entry will be timestamped with the current time.

pub fn get(&self, key: &K) -> Option<&V>

Get a reference to a value if it exists and hasn’t expired.

pub fn get_mut(&mut self, key: &K) -> Option<&mut V>

Get a mutable reference to a value if it exists and hasn’t expired.

pub fn get_timestamp(&self, key: &K) -> Option<Instant>

Get the timestamp when the entry was inserted.

Returns None if the key doesn’t exist or has expired.

pub fn get_age(&self, key: &K) -> Option<Duration>

Get the age of an entry in the cache.

Returns None if the key doesn’t exist or has expired.

pub fn remove(&mut self, key: &K) -> Option<V>

Remove an entry from the cache.

Returns the value if it existed and hadn’t expired, None otherwise.

pub fn remove_with_age(&mut self, key: &K) -> Option<(V, Duration)>

Remove an entry and return both the value and its age.

Useful for calculating rate limit penalties based on order age.

pub fn contains(&self, key: &K) -> bool

Check if a key exists and hasn’t expired.

pub fn cleanup(&mut self)

Remove all expired entries from the cache.

Call this periodically to free memory from expired entries.

pub fn len(&self) -> usize

Get the number of entries in the cache (including expired ones).

pub fn is_empty(&self) -> bool

Check if the cache is empty.

pub fn active_count(&self) -> usize

Get the number of non-expired entries.

pub fn clear(&mut self)

Clear all entries from the cache.

pub fn ttl(&self) -> Duration

Get the TTL duration for this cache.

pub fn set_ttl(&mut self, ttl: Duration)

Set a new TTL duration.

This affects all future checks but doesn’t modify existing timestamps.

Trait Implementations

impl<K: Debug, V: Debug> Debug for TtlCache<K, V>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<K, V> Default for TtlCache<K, V>

where K: Hash + Eq,

fn default() -> Self

Returns the “default value” for a type.