Use System.Threading.Lock on .NET 9.0+ using source generator

[MarkCiliaVincenti]

No description provided.

[gemini-code-assist]

Summary of Changes

Hello @MarkCiliaVincenti, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on modernizing the project's synchronization primitives by adopting System.Threading.Lock for improved performance and consistency with newer .NET versions. It introduces multi-targeting for .NET 9.0 while maintaining full compatibility with existing frameworks through a clever conditional implementation of the locking mechanism. This change enhances the robustness and future-proofing of the codebase.

Highlights

• Updated Locking Mechanism: The synchronization object in GenericFontProvider has been upgraded from a generic System.Object to the more modern System.Threading.Lock.
• Added .NET 9.0 Target Framework: The project now officially targets .NET 9.0, expanding its compatibility and allowing it to leverage newer platform features.
• Conditional Locking Implementation: To ensure backward compatibility, the project uses System.Threading.Lock for .NET 9.0+ and Backport.System.Threading.Lock for older target frameworks (net462, netstandard2.0), managed through conditional MSBuild Using aliases.

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[what-the-diff]

PR Summary

• Improvements to the GenericFontProvider.cs File:

  • The threading model has been made safer by updating the type of _syncLock from an Object to a special Lock object created via LockFactory.Create().

• Updates to the PdfRpt.Core.csproj File:

  • The targeted frameworks for the project now include .NET 9.0.
  • We've updated the language version being used to the latest.
  • A new package named Backport.System.Threading.Lock has been introduced to support the new locking features.
  • To ensure compatibility with .NET 9.0 the project's package references have been updated in various sections.
  • The old package references have been kept for older target frameworks, but conditional statements have been introduced to manage .NET 9.0 specifics.

[gemini-code-assist]

Code Review

This pull request aims to use System.Threading.Lock on .NET 9+ by introducing the Backport.System.Threading.Lock package. While the intention to modernize the locking mechanism is good, the current implementation has a critical issue. System.Threading.Lock is a ref struct in .NET 9 and cannot be used for a static field, which will cause a compilation failure for the net9.0 target. I've provided a comment with details on how to fix this. Additionally, I've found a duplicated section in the .csproj file and suggested a way to combine them for better maintainability. I've also suggested removing the new package dependency if the locking change is reverted.