Add support for Fiber::Scheduler#blocking_operation_wait.

[ioquatix]

This is a very basic implementation of the Fiber::Scheduler#blocking_operation_wait hook.

See https://bugs.ruby-lang.org/issues/20876 for more context.

Types of Changes

• New feature.

Contribution

• I added tests for my changes.
• I tested my changes locally.
• I agree to the Developer's Certificate of Origin 1.1.

[ioquatix]

Confirmed tests passing on ruby-head.

[tenderlove]

Does this mean that every time something releases the GVL, async will create a new thread?

[ioquatix]

Yes the current implementation is a bit naive. I’ll implement a thread pool if it makes sense to do so. The overhead of thread creation isn’t so bad though - will need to spend some time testing it.