Fix potential deadlock in Shared (#3356)

* Fixed shared deadlock. * Fix deadlock> * wip * wip * Improve test.
pointfreeco · Sep 6, 2024 · 2c8b1c0 · 2c8b1c0
1 parent 105bc0f
commit 2c8b1c0
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Showing 4 changed files with 58 additions and 1 deletion.
diff --git a/Sources/ComposableArchitecture/Internal/DispatchQueue.swift b/Sources/ComposableArchitecture/Internal/DispatchQueue.swift
@@ -14,6 +14,20 @@ func mainActorNow<R: Sendable>(execute block: @MainActor @Sendable () -> R) -> R
  }
 }
 
+func mainActorASAP(execute block: @escaping @MainActor @Sendable () -> Void) {
+ if DispatchQueue.getSpecific(key: key) == value {
+ MainActor._assumeIsolated {
+ block()
+ }
+ } else {
+ DispatchQueue.main.async {
+ MainActor._assumeIsolated {
+ block()
+ }
+ }
+ }
+}
+
 private let key: DispatchSpecificKey<UInt8> = {
  let key = DispatchSpecificKey<UInt8>()
  DispatchQueue.main.setSpecific(key: key, value: value)

diff --git a/Sources/ComposableArchitecture/Observation/Binding+Observation.swift b/Sources/ComposableArchitecture/Observation/Binding+Observation.swift
@@ -78,6 +78,7 @@
  }
  }
 
+#if DEBUG
  private final class BindableActionDebugger<Action>: Sendable {
  let isInvalidated: @MainActor @Sendable () -> Bool
  let value: any Sendable
@@ -112,6 +113,7 @@
  }
  }
  }
+#endif
 
  extension BindableAction where State: ObservableState {
  fileprivate static func set<Value: Equatable & Sendable>(

diff --git a/Sources/ComposableArchitecture/SharedState/References/ValueReference.swift b/Sources/ComposableArchitecture/SharedState/References/ValueReference.swift
@@ -395,7 +395,7 @@ final class ValueReference<Value, Persistence: PersistenceReaderKey<Value>>: Ref
  initialValue: initialValue
  ) { [weak self] value in
  guard let self else { return }
- mainActorNow {
+ mainActorASAP {
  #if canImport(Perception)
  self._$perceptionRegistrar.willSet(self, keyPath: \.value)
  defer { self._$perceptionRegistrar.didSet(self, keyPath: \.value) }

diff --git a/Tests/ComposableArchitectureTests/SharedTests.swift b/Tests/ComposableArchitectureTests/SharedTests.swift
@@ -1002,6 +1002,47 @@ final class SharedTests: XCTestCase {
  }
  }
  }
+
+ func testReEntrantSharedSubscriptionDependencyResolution() async throws {
+ for _ in 1...100 {
+ try await withDependencies {
+ $0 = DependencyValues()
+ } operation: {
+ @Shared(.appStorage("count")) var count = 0
+
+ struct Client: TestDependencyKey {
+ init() {
+ @Dependency(\.defaultAppStorage) var userDefaults
+ userDefaults.set(42, forKey: "count")
+ }
+ static var testValue: Self { Self() }
+ }
+
+ withEscapedDependencies { dependencies in
+ DispatchQueue.global().async {
+ dependencies.yield {
+ XCTAssertEqual({ Thread.isMainThread }(), false)
+ @Dependency(Client.self) var client
+ _ = client
+ }
+ }
+ DispatchQueue.main.async { [sharedCount = $count] in
+ dependencies.yield {
+ XCTAssertEqual({ Thread.isMainThread }(), true)
+ _ = sharedCount.wrappedValue
+ }
+ }
+ }
+
+ try await Task.sleep(nanoseconds: 10_000_000)
+ XCTAssertEqual(count, 42)
+ }
+ }
+ }
+}
+
+@globalActor actor GA: GlobalActor {
+ static let shared = GA()
 }
 
 @Reducer