Struct CacheExpander 

pub struct CacheExpander<B: CacheBackend> { /* private fields */ }

Core cache expander - handles cache lookup and fallback logic.

This is the main entry point for cache operations. Supports multiple access patterns through different methods.

Example

use cache_kit::{CacheExpander, backend::InMemoryBackend};

let backend = InMemoryBackend::new();
let mut expander = CacheExpander::new(backend);

Implementations

impl<B: CacheBackend> CacheExpander<B>

pub fn new(backend: B) -> Self

Create new expander with given backend.

pub fn with_metrics(self, metrics: Box<dyn CacheMetrics>) -> Self

Set custom metrics handler.

pub fn with_ttl_policy(self, policy: TtlPolicy) -> Self

Set custom TTL policy.

pub async fn with<T, F, R>( &self, feeder: &mut F, repository: &R, strategy: CacheStrategy, ) -> Result<()>

where T: CacheEntity, F: CacheFeed<T>, R: DataRepository<T>, T::Key: FromStr,

Generic cache operation with strategy.

This is the primary method used in 80% of cases.

Arguments

• feeder: Entity feeder (implements CacheFeed<T>)
• repository: Data repository (implements DataRepository<T>)
• strategy: Cache strategy (Fresh, Refresh, Invalidate, Bypass)

Example

let expander = CacheExpander::new(redis_backend);
let mut feeder = EmploymentFeeder { id: "emp_123", employment: None };
let repo = EmploymentRepository { db: pool };

expander.with(
    &mut feeder,
    &repo,
    CacheStrategy::Refresh
).await?;

let employment = feeder.employment;

Errors

Returns Err in these cases:

• Error::ValidationError: Feeder or entity validation fails
• Error::DeserializationError: Cached data is corrupted or has wrong format
• Error::InvalidCacheEntry: Cache magic header mismatch or invalid envelope
• Error::VersionMismatch: Schema version mismatch between code and cached data
• Error::BackendError: Cache backend is unavailable or network error
• Error::RepositoryError: Database access fails
• Error::Timeout: Operation exceeds timeout threshold
• Error::SerializationError: Entity serialization for caching fails

pub async fn with_config<T, F, R>( &self, feeder: &mut F, repository: &R, strategy: CacheStrategy, config: OperationConfig, ) -> Result<()>

where T: CacheEntity, F: CacheFeed<T>, R: DataRepository<T>, T::Key: FromStr,

Execute cache operation with custom configuration.

This method allows per-operation overrides for TTL and retry logic.

Arguments

• feeder: Entity feeder (implements CacheFeed<T>)
• repository: Data repository (implements DataRepository<T>)
• strategy: Cache strategy (Fresh, Refresh, Invalidate, Bypass)
• config: Operation configuration (TTL override, retry count)

Example

use cache_kit::{OperationConfig, CacheStrategy};
use std::time::Duration;

let config = OperationConfig::default()
    .with_ttl(Duration::from_secs(300))
    .with_retry(3);

expander.with_config(
    &mut feeder,
    &repo,
    CacheStrategy::Refresh,
    config
).await?;

Errors

Returns Err in these cases:

• Error::ValidationError: Feeder or entity validation fails
• Error::DeserializationError: Cached data is corrupted or has wrong format
• Error::InvalidCacheEntry: Cache magic header mismatch or invalid envelope
• Error::VersionMismatch: Schema version mismatch between code and cached data
• Error::BackendError: Cache backend is unavailable or network error
• Error::RepositoryError: Database access fails
• Error::Timeout: Operation exceeds timeout threshold
• Error::SerializationError: Entity serialization for caching fails

Failed operations are retried up to config.retry_count times with exponential backoff.

pub fn backend(&self) -> &B

Get backend reference (for advanced use).

pub fn backend_mut(&mut self) -> &mut B

Get mutable backend reference (for advanced use).