Fix swift_beginAccess issue

[Kyle-Ye]

Summary by CodeRabbit

• Refactor
  • Enhanced the internal update mechanism for shared data, improving robustness during concurrent operations.
  • Refined the thread-safety locking approach to ensure more reliable synchronization without affecting overall functionality.

[coderabbitai]

Walkthrough

The changes modify two components within the codebase. In the ObjectCache class, the increment operation on the clock property is now performed using a wrapping addition operator (&+=) instead of a standard addition, ensuring a bitwise wrapping behavior. In the AtomicBox struct, the locking mechanism for the wrappedValue property in thread utilities has been encapsulated using a safer pointer access method (withUnsafeMutablePointerToHeader), improving clarity and robustness without altering overall functionality.

Changes

Files	Change Summary
Sources/OpenSwiftUICore/Data/Other/ObjectCache.swift	Replaced the standard addition operator (+=) with the wrapping (bitwise) addition operator (&+=) for updating the clock property in the cache's subscript implementation.
Sources/OpenSwiftUICore/Util/ThreadUtils.swift	Modified the locking mechanism in AtomicBox.wrappedValue by encapsulating lock operations within closures using withUnsafeMutablePointerToHeader for safer pointer access.

Sequence Diagram(s)

sequenceDiagram
    participant Caller
    participant ObjectCache
    participant DataStructure
    Caller->>ObjectCache: Request cached item via subscript
    ObjectCache->>DataStructure: Find matching entry
    DataStructure-->>DataStructure: Update clock using &+=
    ObjectCache->>Caller: Return cached item

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sequenceDiagram
    participant User
    participant AtomicBox
    participant HeaderLock
    User->>AtomicBox: Access wrappedValue
    AtomicBox->>HeaderLock: Retrieve mutable pointer via withUnsafeMutablePointerToHeader
    HeaderLock-->>AtomicBox: Perform lock/unlock operations safely
    AtomicBox->>User: Return the value with thread safety

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Poem

I'm a rabbit in the code, hopping with delight,
Skipping through cache updates and locking things tight.
With &+= for our clock and locks handled neat,
Our code dashes forward on nimble little feet.
Cheers and carrots for changes so bright! 🐇
Happy coding in every byte!

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Review profile: CHILL
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📥 Commits

Reviewing files that changed from the base of the PR and between 333104b and 251eda9.

📒 Files selected for processing (2)

• Sources/OpenSwiftUICore/Data/Other/ObjectCache.swift (1 hunks)
• Sources/OpenSwiftUICore/Util/ThreadUtils.swift (1 hunks)

⏰ Context from checks skipped due to timeout of 90000ms (1)

• GitHub Check: Execute tests on Ubuntu (6.0.1)

🔇 Additional comments (2)

Sources/OpenSwiftUICore/Data/Other/ObjectCache.swift (1)

31-31: Good fix to prevent integer overflow issues

Changing from += to &+= is an important improvement that prevents potential crashes from integer overflow. The wrapping addition ensures that when the clock (of type UInt32) reaches its maximum value, it will wrap back to 0 instead of trapping. This is particularly important for a cache implementation that might run for extended periods.

This change also makes the code more consistent since line 35 already uses the wrapping subtraction operator &- when calculating time differences.

Sources/OpenSwiftUICore/Util/ThreadUtils.swift (1)

127-128: Good improvement for memory safety

Using withUnsafeMutablePointerToHeader is a safer approach to access the lock compared to direct access. This change helps ensure proper memory handling and avoids potential issues with Swift's memory exclusivity checking (which seems to be the "swift_beginAccess issue" mentioned in the PR title).

The change preserves the same locking/unlocking behavior but does so through a more structured API, reducing the risk of memory-related bugs. This is a solid improvement while waiting for Swift's native Mutex and Atomic types (as noted in the FIXME comment).

Also applies to: 130-132, 137-142

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 21.61%. Comparing base (333104b) to head (251eda9).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #249      +/-   ##
==========================================
- Coverage   21.63%   21.61%   -0.03%     
==========================================
  Files         329      329              
  Lines       14832    14832              
==========================================
- Hits         3209     3206       -3     
- Misses      11623    11626       +3     

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