Sisyphus Tasks

Utilities for long-running, resilient tasks.

This library contains code I wrote, found useful, and want to keep using. It aims to provide systems

The general idiom is focused on spawning long-lived worker loops, which use channels to communicate.

Understanding this crate

High Level Example

pub struct MyWorker{
  pipe: Pipe<WorkItem>,
}

impl Boulder for MyWorker {
  fn spawn(self) -> JoinHandle<Fall<Self>> {
    tokio::spawn(async move {
      // pipe gives refs to items
      while let Some(item) = self.pipe.next().await {
        // worker does work on each item as it becomes available
        self.do_work_on(item);
        // do some async work too :)
        self.async_work_as_well(item).await;
      }
    });
  }
}

let task = MyWorker::new(a_pipe).run_forever();

Current Utils:

• Sisyphus

  • A scaffolding system for spawning long-lived, recoverable tasks
  • A Boulder is a looping, fallible task
  • Boulder logic is defined in a Boulder::spawn() method that returns a JoinHandle
  • A Fall is an error in that task.
    • Fall::Recoverable - errors that the task believes it can recover
    • Fall::Unrecoverable - errors that the task believes it cannot recover
  • The Boulder::run_until_panic method handles restarting on recoverable Fall s, and reporting unrecoverable errors
  • Boulder s may define custom recovery or cleanup logic
  • Boulder s may also panic. In that case, no Fall is generated, and the
    • panic is propagated upward
  • Sisyphus manages a Boulder loop. He exposes an interface to observe its status and abort the work

• Pipe

  • An inbound and an outbound channel
  • Enforce process-once semantics
  • Prevents data loss on worker error
  • Designed for relatively linear data-processing pipelines
    • e.g. retrieval -> metrics -> indexing -> other handling
  • Convenience methods for running synchronous and asynchronous for_each on channel contents

Future Utils:

• Abstraction layers for instantiating complex pipes from lists of Sisyphuses
• Pipes should allow sync & async transforms (inbound T, outbound U)

Copyright Note

Some code descends from utilities written for Nomad. It is used and reproduced under its license terms.