futures-cache

Futures-aware cache implementation backed by RocksDB.

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 RocksDB (#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"]}
chrono = {version = "0.4.7", features = ["serde"]}
rocksdb = "0.12.2"

You'll also have to install LLVM and clang since these are build dependencies for RocksDB. You can get them at: http://releases.llvm.org/download.html.

Examples

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

enum Key<'a> {
    /// Cache key for the get_user request.
    GetUser(&'a str),
}

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

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

    let mut options = rocksdb::Options::default();
    options.set_compression_type(rocksdb::DBCompressionType::Snappy);
    options.set_keep_log_file_num(16);
    options.create_if_missing(true);

    Ok(Arc::new(rocksdb::DB::open(&options, path)?))
}

fn main() -> Result<(), Box<dyn Error>> {
    let db = setup_db()?;
    let cache = Cache::load(db.clone())?;
    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?;
    });
}