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async-cache

@juriadams/async-cache is an efficient caching utility with asynchronous capabilities for third-party retrieval and revalidation. It is particularly useful when caching third-party API calls where you always expect a value to be returned.

Key Features

  • Time to live (TTL): An item in the cache older than this TTL will be evicted, and retrievals will return undefined.
  • TTL Reset: The TTL of an item can be reset every time it is retrieved from cache.
  • Revalidation: The value of a key can be revalidated every time it's retrieved from the cache. While revalidation is pending, stale data is returned.
  • Layered Revalidation: One or more function can be passed to revalidate a value. Useful when having a separate caching layer (such as KV).
  • Resolving Cache Misses: For cache misses, a custom resolve function resolves and stores items in cache.
  • Layered Resolving: Same as for revalidation, multiple functions can be passed to resolve a value. This way, you can first check faster sources for your data before falling back to the slowest.

Basic Example

import Cache from "@juriadams/async-cache";

const cache = new Cache({
    ttl: 1000 * 10,
    maxSize: 5,

    // Custom resolving for cache misses.
    resolve: [async (key) => KV.get(key), async (key) => S3.get(key)]

    // Custom revalidation.
    revalidate: [async (key) => KV.get(key)],
    revalidateOnGet: true,
});

cache.set("@leo", { permissions: ["read", "write"] });

// Resolved from memory (fast).
await cache.get("@leo");

// First resolved by checking KV (somewhat slow), then S3 (slow).
await cache.get("@juri");

// Subsequent retrievals are returned from memory (fast).
// As `revalidateOnGet` is set, the item is revalidated in the background.
await cache.get("@juri");

// Manually evict items from the cache.
cache.delete("@leo");
cache.delete("@juri");

This code initializes a new Cache() with some options including a TTL, whether to revalidate entries upon retrieval, and the custom resolve/revalidate functions. Then, it demonstrates how to set, get, and delete data from the cache.

For more minimal examples covering all possible cases, please refer to the test suite.

Installation

npm i @juriadams/async-cache

API

Detailed API specifications are a subject to follow.

Contributing

If you want to contribute to this project, please fork the repository, make your changes, and create a pull request. We welcome contributions from the community.

Please note that we ensure 100 % test coverage.