futures-cache

Futures-aware cache backed by sled.

State

The state of the library is:

• API is limited to only wrap, which includes a timeout (#1).
• Requests are currently racing in the wrap method, so multiple unecessary requests might occur when they should instead be queueing up (#2).
• Entries only expire when the library is loaded (#3).
• Only storage backend is sled (#4).

Usage

This library requires the user to add the following dependencies to use:

futures-cache = "0.2.0"
serde = {version = "1.0.97", features = ["derive"]}

Examples

use std::{path::Path, fs, error::Error, sync::Arc};
use futures_cache::{sled, Duration, Cache};
use futures;
use serde::{Serialize, Deserialize};

#[derive(Debug, Serialize)]
enum Key<'a> {
    /// Cache key for the get_user request.
    GetUser(&'a str),
}

fn setup_db() -> Result<sled::Db, Box<dyn Error>> {
    let path = Path::new("path/to/cache");

    if !path.is_dir() {
        fs::create_dir_all(path)?;
    }

    Ok(sled::Db::start_default(path)?)
}

fn main() -> Result<(), Box<dyn Error>> {
    let db = setup_db()?;
    let cache = Cache::load(db.open_tree("cache")?)?;
    let api = Api::new()?;

    futures::executor::block_on(async move {
        // Cache for 12 hours.
        let mary = cache.wrap(Key::GetUser("mary"), Duration::hours(12), api.get_user("mary")).await?;
        // Second request will be cached.
        let mary2 = cache.wrap(Key::GetUser("mary"), Duration::hours(12), api.get_user("mary")).await?;
    });
}