Trait CacheBackend 

pub trait CacheBackend: Send + Sync {
    // Required methods
    fn get<'a>(&'a self, key: &'a str) -> BoxFuture<'a, Option<Bytes>>;
    fn set_with_ttl<'a>(
        &'a self,
        key: &'a str,
        value: Bytes,
        ttl: Duration,
    ) -> BoxFuture<'a, Result<()>>;
    fn remove<'a>(&'a self, key: &'a str) -> BoxFuture<'a, Result<()>>;
    fn health_check(&self) -> BoxFuture<'_, bool>;
    fn name(&self) -> &'static str;

    // Provided method
    fn remove_pattern<'a>(
        &'a self,
        _pattern: &'a str,
    ) -> BoxFuture<'a, Result<()>> { ... }
}

Core cache backend trait for both L1 and L2 caches

This trait defines the essential operations that any cache backend must support. Implement this trait to create custom L1 (in-memory) or L2 (distributed) cache backends.

Required Operations

• get: Retrieve a value by key
• set_with_ttl: Store a value with a time-to-live
• remove: Delete a value by key
• health_check: Verify cache backend is operational

Thread Safety

Implementations must be Send + Sync to support concurrent access across async tasks.

Performance Considerations

• get operations should be optimized for low latency (target: <1ms for L1, <5ms for L2)
• set_with_ttl operations can be slightly slower but should still be fast
• Consider connection pooling for distributed backends

Example

See module-level documentation for a complete example.

Required Methods

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

Get value from cache by key

Arguments

• key - The cache key to retrieve

Returns

• Some(value) - Value found in cache
• None - Key not found or expired

fn set_with_ttl<'a>( &'a self, key: &'a str, value: Bytes, ttl: Duration, ) -> BoxFuture<'a, Result<()>>

Set value in cache with time-to-live

Arguments

• key - The cache key
• value - The value to store (raw bytes)
• ttl - Time-to-live duration

Returns

• Ok(()) - Value successfully cached
• Err(e) - Cache operation failed

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

Remove value from cache

Arguments

• key - The cache key to remove

Returns

• Ok(()) - Value removed (or didn’t exist)
• Err(e) - Cache operation failed

fn health_check(&self) -> BoxFuture<'_, bool>

Check if cache backend is healthy

This method should verify that the cache backend is operational. For distributed caches, this typically involves a ping or connectivity check.

Returns

• true - Cache is healthy and operational
• false - Cache is unhealthy or unreachable

fn name(&self) -> &'static str

Get the name of this cache backend

Provided Methods

fn remove_pattern<'a>(&'a self, _pattern: &'a str) -> BoxFuture<'a, Result<()>>

Remove keys matching a pattern

Arguments

• pattern - Glob-style pattern (e.g. “user:*”)

Returns

• Ok(()) - Pattern processed
• Err(e) - Operation failed

Implementors

impl CacheBackend for DashMapCache

Implement CacheBackend trait for DashMapCache

impl CacheBackend for MokaCache

Implement CacheBackend trait for MokaCache

impl CacheBackend for RedisCache

Implement CacheBackend trait for RedisCache