[ruby-core:101224] [Ruby master Feature#17363] Timeouts

Issue #17363 has been updated by Eregon (Benoit Daloze).


+1 for `Queue#pop(timeout: 42)`.

FWIW TruffleRuby already has `Queue#receive_timeout` as a private method,
and this is used to implement `Timeout.timeout` without creating a new Thread every time.

---

It sounds like the proposed `Timeout.wake{}` would be similar to `Thread#wakeup`.
I'm not sure how it could work, because reading another thread state is always racy (without a GIL), and the thread checking timeouts must be a separate thread than the one doing the blocking call.
Also it could interrupt a blocking call in `ensure` (e.g., cleaning up a connection), which would be unwanted.

----------------------------------------
Feature #17363: Timeouts
https://bugs.ruby-lang.org/issues/17363#change-88907

* Author: marcandre (Marc-Andre Lafortune)
* Status: Open
* Priority: Normal
----------------------------------------
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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