Struct MemoryCache 

pub struct MemoryCache { /* private fields */ }

A cache held in this process.

Right for development, tests, and anything genuinely per-process. Two instances behind a load balancer do not share it, which for a cache is a performance question rather than a correctness one — unlike a session, where it is both.

The exception is anything you cache for correctness: a rate-limit counter or a lock in a memory cache is per-instance, so the limit is really N × limit and the lock is not one.

Implementations

impl MemoryCache

pub fn new() -> Self

An empty cache.

pub fn len(&self) -> usize

How many entries are held, expired ones included.

pub fn is_empty(&self) -> bool

Whether nothing is held.

pub fn purge(&self) -> u64

Drop every expired entry. Returns how many.

Reads clean up the key they touch, but a key never read again would otherwise sit there — so a long-lived process wants this on a timer.

Trait Implementations

impl Cache for MemoryCache

fn is_shared(&self) -> bool

One process. Two instances of the application share nothing here.

fn name(&self) -> &str

A label for diagnostics — "memory", "redis", "memcached".

fn get<'a>(&'a self, key: &'a str) -> BoxFuture<'a, Result<Option<Vec<u8>>>>

The value at key, or None if it is absent or expired.

fn put<'a>( &'a self, key: &'a str, value: &'a [u8], ttl: Option<Duration>, ) -> BoxFuture<'a, Result<()>>

Store value, expiring after ttl. None means no expiry.

fn forget<'a>(&'a self, key: &'a str) -> BoxFuture<'a, Result<bool>>

Remove a key. true if it was there.

fn flush(&self) -> BoxFuture<'_, Result<()>>

Remove everything.

fn add<'a>( &'a self, key: &'a str, value: &'a [u8], ttl: Option<Duration>, ) -> BoxFuture<'a, Result<bool>>

Store value only if key is absent. true if it was stored.

fn forget_if<'a>( &'a self, key: &'a str, expected: &'a [u8], ) -> BoxFuture<'a, Result<bool>>

Remove key only if it currently holds expected. true if it was removed.

fn increment<'a>(&'a self, key: &'a str, by: i64) -> BoxFuture<'a, Result<i64>>

Add by to a counter, creating it at zero first. Returns the new value.

fn supports_atomic_add(&self) -> bool

Whether add is genuinely atomic here.

fn has<'a>(&'a self, key: &'a str) -> BoxFuture<'a, Result<bool>>

Whether a key is present and unexpired.

impl Debug for MemoryCache

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

Formats the value using the given formatter.

impl Default for MemoryCache

fn default() -> Self

Returns the “default value” for a type.