Enum CacheStrategy 

pub enum CacheStrategy {
    Lru(NonZero<usize>),
    NoCache,
}

Strategy for caching topic matching results

Controls how topic match results are cached to optimize performance. Different strategies trade memory usage for lookup speed.

Variants

Lru(NonZero<usize>)

Use LRU (Least Recently Used) cache with a fixed size

Maintains a cache of recently matched topics. When the cache is full, the least recently used entry is evicted. Provides good performance for workloads with repeated topic patterns.

Note: This variant is only available with the lru-cache feature enabled.

Example

use std::num::NonZeroUsize;
use mqtt_topic_engine::CacheStrategy;

let cache = CacheStrategy::Lru(NonZeroUsize::new(100).unwrap());

NoCache

No caching - always create new TopicPath instances

Disables caching entirely. Use this when:

• Topic patterns are rarely repeated
• Memory is constrained
• Simplicity is preferred over performance

Implementations

impl CacheStrategy

pub fn new(capacity: usize) -> CacheStrategy

Create a new cache strategy with the specified capacity

Returns NoCache if capacity is 0, otherwise returns Lru with the given capacity (if lru-cache feature is enabled).

Arguments

• capacity - Maximum number of entries to cache (0 means no caching)

Examples

use mqtt_topic_engine::CacheStrategy;

// Create no-cache strategy
let no_cache = CacheStrategy::new(0);
assert_eq!(no_cache, CacheStrategy::NoCache);

With lru-cache feature:

// Create LRU cache with 100 entries
let cache = CacheStrategy::new(100);

pub fn capacity(&self) -> Option<NonZero<usize>>

Returns the cache capacity if using LRU strategy

Examples

use mqtt_topic_engine::CacheStrategy;

let no_cache = CacheStrategy::NoCache;
assert_eq!(no_cache.capacity(), None);

With lru-cache feature:

use std::num::NonZeroUsize;
use mqtt_topic_engine::CacheStrategy;

let cache = CacheStrategy::new(100);
assert_eq!(cache.capacity(), Some(NonZeroUsize::new(100).unwrap()));

Trait Implementations

impl Clone for CacheStrategy

fn clone(&self) -> CacheStrategy

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for CacheStrategy

impl Debug for CacheStrategy

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

Formats the value using the given formatter.

impl Default for CacheStrategy

fn default() -> CacheStrategy

Default strategy is no caching

This ensures predictable behavior and minimal memory usage by default.

impl Eq for CacheStrategy

impl PartialEq for CacheStrategy

fn eq(&self, other: &CacheStrategy) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for CacheStrategy