Implement new FileStreamStrategy for Unix

[adamsitnik]

#53669 (comment)

cc @stephentoub

Tagging subscribers to this area: @carlossanlop
See info in area-owners.md if you want to be subscribed.

Issue Details

---

#53669 (comment)

cc @stephentoub

Author:	adamsitnik
Assignees:	-
Labels:	area-System.IO
Milestone:	6.0.0

[teo-tsirpanis]

I can do it, I will start working on it in after July 2.

[stephentoub]

I can do it, I will start working on it in after July 2.

@teo-tsirpanis, I hadn't seen this comment, and I was inspired to do it based on your RandomAccess PR. Have you already started? I'm fairly close to done, but if you're already working on it, I can drop mine and let you run with it.

[teo-tsirpanis]

No @stephentoub I haven't started it yet, that was going to be after the RandomAccess PR. Better not drop it though, I don't know how easy or hard it will be for me to do.

[teo-tsirpanis]

I am currently working on it, its progress can be found on https://github.com/teo-tsirpanis/dotnet-runtime/tree/unix-file-stream-strategy, I will submit a PR once ready.

[stephentoub]

Based on your previous response ("Better not drop it though"), I have a PR ready to go; I just need to measure it with your other PR. You're of course welcome to keep working on it, though... maybe you'll come up with a better solution. :-)

[teo-tsirpanis]

OK, better you do it, both PRs are following the same idea either way but yours is already complete and you can locally test and benchmark it (spoiler alert, I could not test the other PR on my machine, it's not powerful enough and does not even have Linux 😳). And you did some things differently better, like the OperatingSystem check for file locking on Macs instead of the pre-existing separate files I moved to FileStreamHelpers.

I reviewed your code and did not find anything I would change.