Storage abstractions and caching utilities for key-value databases.

This crate provides a foundation for building persistent storage systems with efficient caching. It includes:

• Key-Value Database Abstraction ([kv_database]): A trait-based abstraction layer for key-value databases, allowing interchangeable backends (e.g., RocksDB, LMDB, in-memory storage).

• SIEVE Cache ([sieve]): A high-performance, sharded cache implementation using the SIEVE eviction algorithm, which provides excellent hit rates with minimal overhead compared to LRU.

Architecture

The crate is designed around the [kv_database::Column] trait, which defines the schema for key-value pairs including their types and serialization requirements. This allows for type-safe database operations with compile-time guarantees.

The [sieve::Sieve] cache integrates seamlessly with any [kv_database::KvDatabase] implementation, providing transparent caching with lazy loading from the backing store.

Example

use storage::{kv_database::{Column, KvDatabase}, sieve::Sieve};

// Define a column schema
struct UserColumn;
impl Column for UserColumn {
    type Key = u64;
    type Value = String;
}

// Create a cache backed by your database
let cache = Sieve::<UserColumn, MyDatabase, _>::new(
    1000,           // total capacity
    16,             // number of shards
    db,             // backing database
    Default::default(),
);

// Retrieve values (automatically fetched from DB on cache miss)
let value = cache.get(&user_id).await;