Issue #20414 has been updated by ioquatix (Samuel Williams).
Status changed from Open to Closed
Backport changed from 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN to 3.1:
REQUIRED, 3.2: REQUIRED, 3.3: REQUIRED
Merged in
<https://github.com/ruby/ruby/commit/6ade36c06b7cef948099b8f5f483763498705d12>.
----------------------------------------
Bug #20414: `Fiber#raise` should recurse to `resumed_fiber` rather than failing.
https://bugs.ruby-lang.org/issues/20414#change-107962
* Author: ioquatix (Samuel Williams)
* Status: Closed
* Assignee: ioquatix (Samuel Williams)
* Backport: 3.1: REQUIRED, 3.2: REQUIRED, 3.3: REQUIRED
----------------------------------------
The following program will fail with `FiberError`, and is difficult to properly clean up:
```ruby
root_fiber = Fiber.current
f1 = Fiber.new do
root_fiber.transfer
end
f2 = Fiber.new do
f1.resume
end
f2.transfer
f2.raise("error") # => `raise': attempt to transfer to a resuming fiber
(FiberError)
```
This program deliberately set's up a scenario where `f2` is resuming `f1`. Trying to
raise an exception on `f2` is impossible, because the only way control flow can return to
it, is when `f1` yields or exits.
We can avoid this problem, by raising the exception on f1, and we can do this
automatically using the following logic:
```c
static VALUE
fiber_raise(rb_fiber_t *fiber, VALUE exception)
{
// Add this recursive step:
if (fiber->resuming_fiber) {
return fiber_raise(fiber->resuming_fiber, exception);
}
// Existing code ...
else if (FIBER_SUSPENDED_P(fiber) && !fiber->yielding) {
return fiber_transfer_kw(fiber, -1, &exception, RB_NO_KEYWORDS);
}
else {
return fiber_resume_kw(fiber, -1, &exception, RB_NO_KEYWORDS);
}
}
```
This makes `Fiber#raise` much more robust and useful for the purpose of stopping fibers,
without knowing exactly what they are doing.
--
https://bugs.ruby-lang.org/