Use System.Threading.Lock where applicable

[BCSharp]

Performance improvement: System.Threading.Lock provides a more efficient locking primitive in .NET 9.0+ than locking on a generic object.

[slozier]

Works for me.

I was trying to see if there was a "cleaner" pattern, but only think I came up with was putting an alias at the top:

#if !NET9_0_OR_GREATER
using Lock = System.Object;
#endif

[BCSharp]

Thanks for the review. I want to do the same in IronPython so let's agree here on the pattern, so it matches across the projects.

[slozier]

Interesting. Not sure how I feel about global usings, they seem a bit too magical. 😄 But I'm willing to give it a try... I can see how having if conditions would become noisy with the amount of locks used in IronPython.

Alternate in between solution to make it a little less magical could be do drop the global using on .NET 9+ and require using System.Threading for each file that uses it? Just a thought, don't have a strong opinion about it.

[BCSharp]

Not sure how I feel about global usings, they seem a bit too magical. 😄 But I'm willing to give it a try...

Well, I do have an opinion on them and my personal preferences. Generally, I am rather conservative:

1. I strongly dislike implicit usings, except for single-file programs.
2. I prefer file-scope usings, but allow for global usings for very limited and justified cases that significantly cut down the ceremony. That usually means types that are not specific to any code area and/or are widely used (rather than whole namespaces), or standard boilerplate XAML namespaces.
3. I dislike global usings defined in .csproj or .props files. Global usings are already somewhat — as you say — “magical”, and having them buried inside XML files just feels too obscure. So I like a dedicated .cs file for global usings only, even though it means one extra file at the top level.

In this practical case it means that Lock is qualified to be introduced as a global using alias, since it serves a specific but universal purpose across the code base. However, I'd rather have it defined in a dedicated .cs file, not directly in Directory.Build.props. I put it here inside .props only because IronPython already defines a global usings alias in its Directory.Build.props (NotNoneAttribute) and I tried to be consistent, but that was not my preference.

Alternate in between solution to make it a little less magical could be do drop the global using on .NET 9+ and require using System.Threading for each file that uses it? Just a thought, don't have a strong opinion about it.

I'm not sure I understand how this would work without #ifs polluting the code, since Lock should be Object for pre-.NET 9 targets.

Anyway, I am going to commit my preferred form now, counting on your willing to give it a try. I'll let you merge the PR is you are OK with it, otherwise looking forward to your opinion.

[slozier]

I guess I didn't explain myself well regarding my alternate solution. I meant only keeping the global using for pre .NET 9:

#if !NET9_0_OR_GREATER
global using Lock = System.Object;
#endif

so that using Lock would still require a file-scoped using System.Threading on .NET 9+.