[ruby-core:102465] [Ruby master Feature#17363] Timeouts

Issue #17363 has been updated by ioquatix (Samuel Williams).


This seems like a good idea.

I agree with the following things:

- Move `Timeout` to core.
- Add `Timeout::Error` as base class in core.
- Add new method for predictable timeout during sleeping operations (e.g. `Timeout.wake` or something similar).

In terms of queue and ractor, I'm less inclined to support:

- `timeout:` keyword argument.
- Custom exception classes for Ractor, Queue and so on.

I'm not against it, I'm just not sure if it's useful in practice. I think the latter feature should be separate issue/PR if possible.

Finally, I'd also like to suggest that we deprecate `Timeout.timeout` once this is merged.



----------------------------------------
Feature #17363: Timeouts
https://bugs.ruby-lang.org/issues/17363#change-90353

* Author: marcandre (Marc-Andre Lafortune)
* Status: Assigned
* Priority: Normal
* Assignee: ko1 (Koichi Sasada)
----------------------------------------
Builtin methods like `Queue.pop` and `Ractor.receive` have no timeout parameter.

We should either:
- provide such a parameter
- and/or provide a `Timeout::wake` that raises an timeout error only if the block is currently sleeping.

Details:

```ruby
q = Queue.new
# ...
elem = Timeout::timeout(42) { q.pop } # => It is possible that an element is retreived from the queue but never stored in `elem`

elem = Timeout::wake(42) { q.pop } # => Guaranteed that either element is retrieved from the queue or an exception is raised, never both
Timeout::wake(42) { loop {} } # => infinite loop
# and/or
elem = q.pop(timeout: 42)
```

Currently, the only reliable way to have a Queue that accepts a timeout is to re-implement it from scratch. This post describe how involved that can be: https://spin.atomicobject.com/2017/06/28/queue-pop-with-timeout-fixed/



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