Umbral Cache

The fastest query is the one you don't run twice. Umbral Cache installs a process-wide in-memory cache as an ambient handle — reach for it from any handler to memoise an expensive aggregate, a rendered fragment, or a third-party API response. When a whole page is safe to share, an opt-in cache_page layer caches the entire response. No client to configure, no keys to manage in dev.

Install

cargo add umbral-cache

Wire it up

use umbral::prelude::*;
use umbral_cache::{CachePlugin, Cache};

let app = App::builder()
    .database("default", pool)
    .plugin(CachePlugin::new(Cache::memory()))
    .build()?;

Target: memoise an expensive dashboard query

Read from the ambient handle, compute on a miss, store for next time.

use umbral_cache::ambient;

async fn stats() -> Stats {
    if let Some(hit) = ambient().get::<Stats>("dashboard:stats").await {
        return hit;
    }
    let fresh = compute_expensive_stats().await;   // the slow path, once
    ambient().set("dashboard:stats", &fresh, /* ttl */ 60).await;
    fresh
}

What you get

• Process-wide in-memory cache as an ambient handle
• Reach it from any handler — no wiring through call stacks
• Opt-in cache_page layer for whole-response caching
• A pluggable backend so a shared store can slot in later