Use Mutex directly instead of ThreadSafeBox for class/actor stored properties#2695
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rintaro wants to merge 1 commit into
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Use Mutex directly instead of ThreadSafeBox for class/actor stored properties#2695rintaro wants to merge 1 commit into
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ThreadSafeBox is a `class` wrapping a `Mutex<Value>`. When stored as a property of another class or actor, the outer reference type already provides identity, so the extra ThreadSafeBox class indirection is just a redundant heap allocation. Replace `ThreadSafeBox<T>` with `Mutex<T>` at those sites. Function-local ThreadSafeBox uses are unchanged since they need class identity to be capturable in `@Sendable` closures. CustomBuildServerTestProject.buildServerBox is also unchanged: it is value-captured into a closure stored before `super.init`, which a ~Copyable Mutex can't support without a class wrapper. Port SourceKitD's fileprivate `computeIfNil` extension from ThreadSafeBox to Mutex (now `borrowing`).
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swiftlang/swift-tools-protocols#66 |
hamishknight
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Jun 18, 2026
ahoppen
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Jun 19, 2026
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swiftlang/swift-tools-protocols#66 |
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swiftlang/swift-tools-protocols#66 |
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ThreadSafeBoxis aclasswrapping aMutex<Value>. When stored as a property of another class or actor, the outer reference type already provides identity, so the extra indirection is just a redundant heap allocation. ReplaceThreadSafeBox<T>withMutex<T>at those sites.Port
SourceKitD's fileprivatecomputeIfNilextension fromThreadSafeBoxtoMutex(nowborrowing).