fix unsafe use of os_unfair_lock

[morganchen12]

See the docs for OSAllocatedUnsafeLock for details.

[gemini-code-assist]

Hello @morganchen12, 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!

Summary of Changes

This pull request addresses an unsafe use of os_unfair_lock by replacing it with OSAllocatedUnfairLock. This change is applied across multiple files in the Firebase codebase, specifically in AuthComponent.swift, Functions.swift, Storage.swift, and VertexAI.swift. The core of the change involves replacing the initialization and usage of os_unfair_lock with OSAllocatedUnfairLock to ensure proper memory management and avoid potential issues related to lock lifecycle.

Highlights

• Locking Mechanism Update: The os_unfair_lock is replaced with OSAllocatedUnfairLock for safer lock management.
• Concurrency Safety: This change enhances concurrency safety by ensuring proper allocation and deallocation of the lock.
• Code Modernization: The code is updated to use a more modern and safer approach to managing unfair locks in Swift.

Changelog

Click here to see the changelog

• FirebaseAuth/Sources/Swift/Auth/AuthComponent.swift
  • Replaced os_unfair_lock with OSAllocatedUnfairLock for the instancesLock property (line 36).
  • Updated the auth() function to use instancesLock.lock() and instancesLock.unlock() instead of os_unfair_lock_lock and os_unfair_lock_unlock (lines 61 and 64).
• FirebaseFunctions/Sources/Functions.swift
  • Replaced os_unfair_lock with OSAllocatedUnfairLock for the instancesLock property (line 59).
  • Updated the function to use instancesLock.lock() and instancesLock.unlock() instead of os_unfair_lock_lock and os_unfair_lock_unlock (lines 307 and 310).
• FirebaseStorage/Sources/Storage.swift
  • Replaced os_unfair_lock with OSAllocatedUnfairLock for the instancesLock property (line 252).
  • Updated the storage() function to use instancesLock.lock() and instancesLock.unlock() instead of os_unfair_lock_lock and os_unfair_lock_unlock (lines 257 and 258).
• FirebaseVertexAI/Sources/VertexAI.swift
  • Moved the declaration of instancesLock above the #if compiler(>=6) block (line 128).
  • Replaced os_unfair_lock with OSAllocatedUnfairLock for the instancesLock property (line 128).
  • Removed the duplicate instancesLock declaration inside the #else block (line 140).
  • Updated the function to use instancesLock.lock() and instancesLock.unlock() instead of os_unfair_lock_lock and os_unfair_lock_unlock (lines 149 and 152).

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In what year was the first version of Swift released?

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Swift was first released by Apple in 2014.

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[gemini-code-assist]

Code Review

This pull request addresses an unsafe use of os_unfair_lock by replacing it with OSAllocatedUnfairLock. This is a good change as it aligns with Apple's recommendations for using unfair locks. The changes are straightforward and seem correct.

Summary of Findings

• Potential typo in FirebaseStorage: There might be a typo in FirebaseStorage/Sources/Storage.swift where OSAllocatedUnfairLock is used without parentheses, potentially instantiating the type instead of creating an instance. This could lead to unexpected behavior.

Merge Readiness

The pull request is generally well-implemented and addresses an important issue. However, the potential typo in FirebaseStorage/Sources/Storage.swift should be investigated and corrected before merging. I am unable to approve this pull request, and recommend that others review and approve this code before merging. Given the potential for a critical issue, I recommend that the pull request not be merged until this is addressed.

[morganchen12]

Commented on the internal gemini bug for the CLA check. Presumably we can manually add the cla: yes tag to work around it for now.

[gemini-code-assist]

Thanks for flagging this, @morganchen12. It's good to know there's a workaround for the CLA check while the internal bug is being addressed.

[morganchen12]

Looks like we can't merge this until we raise our platform floor to iOS 16, since otherwise OSAllocatedUnfairLock is unavailable (see Auth quickstart test failure).