Support abandoning jobs that take too long to cancel

Context

Hiya, thanks for making River! Really digging it so far.

I have an app that queues jobs that I don't really need to wait to complete before exiting, even after cancelling. I just want to guarantee fast deploys and let jobs just get tossed around like a hot potato during a rolling deploy.

Before I continue: this isn't blocking me, and it's a nuanced topic on an edge case within an edge case, so no rush.

StopAndCancel is almost what I want. Cancelled jobs end up in a retryable state and they either get picked back up elsewhere or recovered when the instance comes back. The one case it doesn't handle is when jobs take too long to stop (typically by not respecting ctx.Done(), likely a bug).

I tried to pass a timeout ctx to StopAndCancel, but it doesn't currently respect it:

stopCtx, stop := context.WithTimeout(context.Background(), 10*time.Second)
defer stop()
if err := db.workerClient.StopAndCancel(stopCtx); err != nil {
	slog.Error("failed to stop and cancel workers", "error", err)
}
if stopCtx.Err() != nil {
	slog.Warn("timed out cleaning up jobs")
}

With a job that does time.Sleep(time.Minute) the StopAndCancel will just wait the full 1 minute instead of being interrupted after 10 seconds. This seems like a simple bug, happy to submit a PR.

Even if it did respect the timeout, there's a secondary problem: if we bail out at that point, the worker's jobs will be left in a running state. At this point the job is stuck, and if you have uniqueness rules like I do that'll prevent future attempts too. As far as I can tell the only recourse at this point is to delete the job from the database or set its state to retryable.

Proposal

This might be problematic for other use cases, but at least for mine, this would be a big help:

1. StopAndCancel respects ctx cancellation
2. When StopAndCancel times out it marks all running jobs on the local worker as retryable

Alternatively, having some way to do (2) independently would be fine. For example I could do a db.workerClient.Abandon(stopCtx) in the if stopCtx.Err() != nil { branch above.

This would allow graceful shutdown in most cases, prevent hanging in the "truly stuck" case, and allow jobs to be retried in all cases except kill -9.

Alternative

The root of the problem here is really the stuck running jobs. I would also be OK with leaving everything as-is and instead just enforcing a stop timeout at the infra layer, letting the app get kill -9ed, and having River automatically detect when a running job is abandoned so things aren't stuck forever.

Start at the StopAndCancel entry point and reproduce the behavior with a job that sleeps for one minute and a ten-second timeout context. Trace how cancellation and running-job state are handled; the desired outcome is a bounded stop and a defined way for locally running jobs to become retryable when abandonment occurs.