Question 1

How to set up cached with Redis for async functions in Rust?

Accepted Answer

Enable the `redis_tokio` or `redis_smol` feature, use the `#[io_cached]` macro with `AsyncRedisCache`, specify a creation block with a prefix and duration, and provide a `map_error` closure for error handling, as shown in the async Redis example.

Question 2

cached vs lru-cache crate: which is better for memoization?

Accepted Answer

`cached` is better for declarative memoization with macros and multiple backends, while `lru-cache` is a lower-level data structure. Choose `cached` for ease of use and integrated features like time expiration, or `lru-cache` for manual control over cache logic.

Question 3

Why does the cached macro fail inside an impl block?

Accepted Answer

The macros expand to include `once_cell` initializations and separate function definitions, which conflict with Rust's trait and impl syntax. You must define the function outside the impl or use workarounds like associated functions.

Question 4

How to handle cache expiration with time-based stores?

Accepted Answer

Use `#[cached]` with `ty = "TimedCache"` and specify the `time` parameter, or use `#[once(time=10)]` for single-call caching with expiration. Enable the `time_stores` feature and refer to examples in the docs for configuration.

Question 5

Can I use cached with disk storage for persistent caching?

Accepted Answer

Yes, enable the `disk_store` feature and use `#[io_cached(disk = true)]` or manually create a `DiskCache`. Note that a `map_error` closure is required to handle disk I/O errors, as illustrated in the disk cache example.

Question 6

What's the performance overhead of using cached macros?

Accepted Answer

Overhead includes mutex locking for thread safety and cloning of arguments and return values (except for Redis, which uses serialization). For performance-critical paths, benchmark against manual caching, but the convenience often justifies the cost for general use.

cached

What is cached?

Overview

Use Cases

Best For

Related Projects

Found a gem we're missing?

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions