Correctly inherit fiber refs in ZIO.raceWith
#1594
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| inheritFiberRefs = inherit.get.flatMap { | ||
| case None => ZIO.unit | ||
| case Some(true) => left2.inheritFiberRefs |
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There is a more direct way to encode this: use Ref[Task[Unit]]. Then you can start that Ref off with ZIO.unit, and then you can either stick left2.inheritFiberRefs into that, or right2.inheritFiberRefs into it, depending on the race outcome.
This will simplify the code a lot.
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Hmm, you can't access the currently executing fiber, can you? Because to do the refactoring you propose, I would need to access either left2 or right2 from within arbiter, which is not possible otherwise. Also note that simply inheriting from left or right is not correct, because if the winning fiber failed, the caller might have joined the loosing fiber (which is exactly what raceEither does).
Or maybe I didn't understand you correctly?
| race: Ref[Int], | ||
| waitForLeft: Boolean, | ||
| race: Ref[Boolean], | ||
| inherit: Ref[Option[Boolean]], |
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This would change to Ref[Task[Unit]], see below.
| loser: Fiber[E1, B], | ||
| race: Ref[Int], | ||
| waitForLeft: Boolean, | ||
| race: Ref[Boolean], |
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Can we rename this to raceDone?
| winner: Fiber[E0, A], | ||
| loser: Fiber[E1, B], | ||
| race: Ref[Int], | ||
| waitForLeft: Boolean, |
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Without the refactoring proposed above - yes, we need this to have the necessary context information in arbiter if I'm not mistaken. I've renamed it to leftWins though...
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With these changes if we race two effects with |
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@adamgfraser yes, if the looser wasn't a bad looser that is ;-) - I mean if the looser did not fail. There is a test that checks for this: https://github.com/zio/zio/pull/1594/files#diff-b3f6f229206b73e705ea7e4c6e03784bR23 |
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@mlangc Thanks! It looks like right now we are testing that one or the other |
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@adamgfraser thanks a lot for bringing this up! After adding tests for |
We have to call `inheritFiberRefs` on the winner *before* calling the user supplied function `f`, because we want `FiberRef` related updates from `f` to win over updates from the winning fiber.
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Looks great to me! @adamgfraser thanks for pointing out the need for new tests!
* Correctly inherit fiber refs in `ZIO.raceWith` Fixes zio#1515 * Cosmetics * Don't overwrite already inherited fiber refs in `raceWith` We have to call `inheritFiberRefs` on the winner *before* calling the user supplied function `f`, because we want `FiberRef` related updates from `f` to win over updates from the winning fiber.
Fixes #1515