typelevel / typelevel/cats-effect

`Queue#mapK` violates atomicity guarantees

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:beetle: bug
Dominant language
Scala
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Merged PRs (30d)
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Description

The implementations are not wrapped in the relevant uncancelables, meaning that it's possible to lose elements in mapK'd Queues where it is impossible with the direct implementation.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Locate the implementations of Queue#mapK and compare them with the direct Queue implementation, focusing on the relevant uncancelable boundaries. Verify that mapped queues cannot lose elements during cancellation, and add or update coverage for the atomicity behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
scala
Domain
backend
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
45/100

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