Improvements for .NET 8

[ltrzesniewski]

Here's a list of things to look at once we add a net8.0 target:

• The CompositeFormat class. I don't think we need it since it doesn't parse the format strings eagerly (at least ATM).
• Type.IsEnum and Type.GetEnumUnderlyingType are now intrinsics:
  Make Type.IsEnum and Type.GetEnumUnderlyingType intrinsics dotnet/runtime#71685
• FrozenDictionary/FrozenSet
• Unsafe.BitCast: Adding System.Runtime.CompilerServices.Unsafe.BitCast dotnet/runtime#82917
• IUtf8SpanFormattable, Utf8.TryWrite, Encoding.TryGetBytes
• TimeProvider instead of hard-coded clock: API to provide the current system time dotnet/runtime#36617
• Source Link is part of the .NET SDK
• [ConstantExpected] on parameters

New C#/Roslyn features:

• Interceptors: [Proposal]: Interceptors dotnet/csharplang#7009

This list will be updated with each blog post about .NET 8 🙂

[ltrzesniewski]

Well, I'm not sure any item in this list can be used actually 😢

• CompositeFormat: ZeroLog doesn't use composite formatting APIs
• Enum intrinsics: these methods aren't used in a hot path
• Frozen collections: we don't use read-only collections, so no opportunity to use those
• Unsafe.BitCast: could be useful in one place, but not in a hot path
• IUtf8SpanFormattable, Utf8.TryWrite: that's the real good stuff - I wrote a POC in the utf8 branch which formats directly to UTF-8 bytes, but unfortunately that doesn't seem to improve the perf. Given that it duplicates a lot of code I don't think it's worth the effort to maintain.
• TimeProvider: that's not perf-related but could be a useful new feature (there's even a TODO for this)
• [ConstantExpected]: I didn't find good uses for this in ZeroLog
• Interceptors: they're still experimental but could be interesting later

Profiling shows we spend a lot of time formatting DateTime and TimeSpan values, so maybe we could try to improve those first. Given that we use custom format strings the performance is hindered as those are parsed for each logged message. Maybe we should provide our own formatters, like in ZeroLog v1?