100 lines
2.9 KiB
Markdown
100 lines
2.9 KiB
Markdown
# noworkers
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A small, ergonomic Rust crate for spawning and supervising groups of asynchronous “workers” on Tokio.
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Manage concurrent tasks with optional limits, cancellation, and first-error propagation.
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Inpired by golang (errgroups)
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## Features
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- **Unlimited or bounded concurrency** via `with_limit(usize)`.
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- **Cancellation support** with [`tokio_util::sync::CancellationToken`]—either external (`with_cancel`) or task-driven (`with_cancel_task`).
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- **First-error wins**: the first worker to fail cancels the rest and reports its error.
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- **Graceful shutdown**: `.wait()` awaits all workers, cancels any in-flight tasks, and returns the first error (if any).
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## Installation
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Add to your `Cargo.toml`:
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```toml
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[dependencies]
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noworkers = "0.1"
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````
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Then in your code:
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```rust
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use noworkers::Workers;
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use tokio_util::sync::CancellationToken;
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```
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## Quick Example
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```rust,no_run
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use noworkers::Workers;
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use tokio_util::sync::CancellationToken;
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#[tokio::main]
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async fn main() -> anyhow::Result<()> {
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// Create a worker group with up to 5 concurrent tasks
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let mut workers = Workers::new();
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workers
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.with_limit(5)
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.with_cancel(&CancellationToken::new());
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// Spawn 10 async jobs
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for i in 0..10 {
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workers.add(move |cancel_token| async move {
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// Respect cancellation, or not, if you don't care about blocking forever
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tokio::select! {
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_ = tokio::time::sleep(tokio::time::Duration::from_secs(1)) => {
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println!("Job {i} done");
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Ok(())
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}
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_ = cancel_token.cancelled() => {
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println!("Job {i} cancelled");
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Ok(())
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}
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}
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}).await?;
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}
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// Wait for all to finish or for the first error
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workers.wait().await?;
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Ok(())
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}
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```
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## API Overview
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* `Workers::new() -> Workers`
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Create a fresh worker group.
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* `with_limit(limit: usize) -> &mut Self`
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Bound in-flight tasks to `limit`, back-pressuring `.add()` calls when full.
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* `with_cancel(token: &CancellationToken) -> &mut Self`
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Tie this group’s lifetime to an external token.
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* `with_cancel_task(fut: impl Future<Output=()>) -> &mut Self`
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Spawn a task that, when it completes, cancels the group.
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* `add<F, Fut>(&self, f: F) -> anyhow::Result<()>`
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Spawn a new worker. `f` is a closure taking a child `CancellationToken` and returning `Future<Output=anyhow::Result<()>>`.
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* `wait(self) -> anyhow::Result<()>`
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Await all workers. Returns the first error (if any), after cancelling in-flight workers.
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## Error Handling
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* The **first** worker to return `Err(_)` wins: its error is sent on a oneshot and all others are cancelled.
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* Subsequent errors are ignored.
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## License
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Dual-licensed under **MIT** or **Apache-2.0**.
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See [LICENSE-MIT](LICENSE-MIT) and [LICENSE-APACHE](LICENSE-APACHE) for details.
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```
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