Might be nice to have a convenience method Fiber#join Just so we don’t have to have a “done channel” every time we want to learn when a fiber exits… :slight_smile: -roger-

What would exit? do? Check if it’s still running?

I think they want something that will pause the current fiber until the awaited one finished. That would need some integration with the scheduler. And would allow hooking to running fibers for which the body is unknown or already set, hence it is not possible to add a done.send.

Just an experiment, far from elegant: define a subclass of Fiber - let’s call it JoinableFiber - where we initialise a done channel at creation time define a #join method that receives on it [the hacky bit] override #run with a copy-pasted version from Fiber, where we send to done just before inv…

Note that: done.send will block until a receive is performed (mind if there are no joins executed) only one join will be awaken But definitely the monkey-patch extension is a way to check if the functionality is worth it. It can probably be applied directly to Fiber, without subclassing it.

[image] bcardiff: done.send will block until a receive is performed (mind if there are no joins executed) @done.send won’t block, as @done has capacity 1 - I should have highlighted that. This means that JoinableFiber will complete properly, no matter if join is invoked or not.

[image] bcardiff: It can probably be applied directly to Fiber , without subclassing it. But that would mean any fiber that is not explicitly joined will linger indefinitely. In general, I’d prefer a solution as suggested in [RFC] Structured Concurrency · Issue #6468 · crystal-lang/crystal ·…

:man_facepalming: I didn’t see it was a buffered channel. Sorry!

Fiber#join

Crystal Contrib

sol.vin November 19, 2019, 11:26am 4

Yes

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Fiber#join

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