This allows deployment on wasm32-unknown-unknown.

It is important to understand that Redb's StorageBackend interface is fundamentally synchronous, and OPFS is fundamentally asynchronous. There's a simple way to tie these two things together--block_on--but that method is illegal on the main thread, in order not to block the UI.

This gives rise to two use cases.

This case is nice and simple; everything stays within Rust. Just explicitly choose this backend when initializing your Database:

use redb_opfs::OpfsBackend;

let database = redb::Builder::new()
  .create_with_backend(OpfsBackend::new("my-db")?)?;

In this case we need to instantiate the OpfsBackend on a web worker and then instantiate the handle on the main thread.

You'll want to use the worker-shim.js worker file to initialize the worker, and then hand that worker to the OpfsBackendHandle

import { WorkerHandle } from "./redb-opfs";

const redbOpfsWorker = new Worker("worker-shim.js");
const workerHandle = WorkerHandle(redbOpfsWorker);

// now pass that handle to your rust code, using a mechanism of your choice.

As you're writing your own Rust anyway, you have your own means of getting the handle into your code from there. To keep life simple, there exists impl TryFrom<JsValue> for WorkerHandle.

Once you have that, usage is fairly simple:

use redb_opfs::WorkerHandle;

let worker_handle = WorkerHandle::try_from(my_js_value)?;
let database = redb::Builder::new()
  .create_with_backend(worker_hanndle)?;

• wasm-bindgen cli
• wasm-pack
• GNU Make

This example demonstrates the simplest possible case: redb-opfs is compiled to WASM and deployed, where it is used only from Typescript code without interacting at all with other Rust code. In this use case, the only thing it gives us is a fully-synchronous interface to OPFS.

• bun
• miniserve

• make web-worker-example
• point your browser at any of the listed URLs the server has bound itself to

This example demonstrates the first "real" use case: a Rust library uses redb internally. The rust code is all exclusively contained within the web worker.

The application is a toy click tracker: records the timestamp of each click of a button. Reports the total number of clicks, and n clicks over some aggregated time periods.

• bun
• miniserve

• make rust-in-web-worker-example
• point your browser at any of the listed URLs the server has bound itself to

Licensed only under GPL-3.0.

Any contribution intentionally submitted for inclusion in this work shall be licensed as above, without any additional terms or conditions.