purescript-contrib / purescript-concurrent-queues

An unbounded and bounded queue for concurrent access.

Concurrent Queues

An unbounded and bounded queue for concurrent access.

Installation

Install concurrent-queues with Spago:

spago install concurrent-queues

Quick start

The quick start hasn't been written yet (contributions are welcome!). The quick start covers a common, minimal use case for the library, whereas longer examples and tutorials are kept in the docs directory.

Documentation

concurrent-queues documentation is stored in a few places:

1. Module documentation is published on Pursuit.
2. Written documentation is kept in the docs directory.
3. Usage examples can be found in the test suite.

If you get stuck, there are several ways to get help:

• Open an issue if you have encountered a bug or problem.
• Ask general questions on the PureScript Discourse forum or the PureScript Discord chat.

Contributing

You can contribute to concurrent-queues in several ways:

1. If you encounter a problem or have a question, please open an issue. We'll do our best to work with you to resolve or answer it.

2. If you would like to contribute code, tests, or documentation, please read the contributor guide. It's a short, helpful introduction to contributing to this library, including development instructions.

3. If you have written a library, tutorial, guide, or other resource based on this package, please share it on the PureScript Discourse! Writing libraries and learning resources are a great way to help this library succeed.

purescript-concurrent-queues's Issues

Library has inadequate documentation in the docs directory

Is your change request related to a problem? Please describe.
As described in the documentation section of the Library Guidelines, Contributors libraries are expected to have some documentation in the docs directory -- specifically, a changelog and at least a short tutorial that expands on the quick start in the README.

This library currently doesn't have an up to date changelog or any extra documentation in the docs directory.

Describe the solution you'd like
The argonaut-codecs docs directory has a good example of expanded documentation for a Contributor library. But it would even be useful to add something considerably smaller and shorter to this library.

Additional context
See the Governance repository for more information about requirements in the Contributors organization.

Repository doesn't have a quick start section in the README

Is your change request related to a problem? Please describe.
As described in the documentation section of the Library Guidelines, Contributors libraries are expected to have in their README a short summary of the library's purpose, installation instructions, a quick start with a minimal usage example, and links to the documentation and contributing guide.

This library currently doesn't have a quick start in the README.

Describe the solution you'd like
The library needs a quick start section after the installation instructions. machines is one example of a library with a quick start.

Additional context
See the Governance repository for more information about requirements in the Contributors organization.

Deadlocks In ParAff / Kills

There are several cases where deadlocks will occur if a Queue is used in any Fiber which is killed (ParAff is a common scenario).

read ∷ ∀ a. Queue a → Aff a
read (Queue q) = do
  readEnd ← AVar.take q.readEnd
  // Kill here leaves readEnd empty
  QItem a newRead ← AVar.read readEnd
  AVar.put newRead q.readEnd
  pure a

Invincibility is not a solution because that will lead to external deadlock problems. I have been long down this road with Aff, and even patched the library to fix a critical temporal issue that will also be at play here. When I am able to share the fix I will.