[test] Tests for weak reference read-read thread safety

Dispatch-based tests exist because (on OS X) they are more likely to encounter the race condition than `StdlibUnitTest`'s `runRaceTest()` is.

Author: glessard

test/Runtime/weak-reference-racetests-dispatch.swift

@@ -0,0 +1,108 @@
+// RUN: %target-run-simple-swift
+// REQUIRES: executable_test
+
+// REQUIRES: objc_interop
+
+import StdlibUnittest
+
+// Also import modules which are used by StdlibUnittest internally. This
+// workaround is needed to link all required libraries in case we compile
+// StdlibUnittest with -sil-serialize-all.
+import SwiftPrivate
+#if _runtime(_ObjC)
+import ObjectiveC
+#endif
+
+import Dispatch
+
+let iterations = 200_000
+
+class Thing {}
+
+class WBox<T: AnyObject> {
+  weak var wref: T?
+  init(_ ref: T) { self.wref = ref }
+  init() { self.wref = nil }
+}
+
+let WeakReferenceRaceTests = TestSuite("WeakReferenceRaceTests")
+
+WeakReferenceRaceTests.test("class instance property [SR-192] (copy)") {
+  let q = dispatch_queue_create("", DISPATCH_QUEUE_CONCURRENT)!
+
+  // Capture a weak reference via its container object
+  // "https://bugs.swift.org/browse/SR-192"
+  for i in 1...iterations {
+    let box = WBox(Thing())
+    let closure = {
+      let nbox = WBox<Thing>()
+      nbox.wref = box.wref
+      _blackHole(nbox)
+    }
+
+    dispatch_async(q, closure)
+    dispatch_async(q, closure)
+  }
+
+  dispatch_barrier_sync(q) {}
+}
+
+WeakReferenceRaceTests.test("class instance property [SR-192] (load)") {
+  let q = dispatch_queue_create("", DISPATCH_QUEUE_CONCURRENT)!
+
+  // Capture a weak reference via its container object
+  // "https://bugs.swift.org/browse/SR-192"
+  for i in 1...iterations {
+    let box = WBox(Thing())
+    let closure = {
+      if let ref = box.wref {
+        _blackHole(ref)
+      }
+    }
+
+    dispatch_async(q, closure)
+    dispatch_async(q, closure)
+  }
+  
+  dispatch_barrier_sync(q) {}
+}
+
+WeakReferenceRaceTests.test("direct capture (copy)") {
+  let q = dispatch_queue_create("", DISPATCH_QUEUE_CONCURRENT)!
+
+  // Capture a weak reference directly in multiple closures
+  for i in 1...iterations {
+    weak var wref = Thing()
+    let closure = {
+      let nbox = WBox<Thing>()
+      nbox.wref = wref
+      _blackHole(nbox)
+    }
+
+    dispatch_async(q, closure)
+    dispatch_async(q, closure)
+  }
+
+  dispatch_barrier_sync(q) {}
+}
+
+WeakReferenceRaceTests.test("direct capture (load)") {
+  let q = dispatch_queue_create("", DISPATCH_QUEUE_CONCURRENT)!
+
+  // Capture a weak reference directly in multiple closures
+  for i in 1...iterations {
+    weak var wref = Thing()
+    let closure = {
+      if let ref = wref {
+        _blackHole(ref)
+      }
+    }
+
+    dispatch_async(q, closure)
+    dispatch_async(q, closure)
+  }
+
+  dispatch_barrier_sync(q) {}
+}
+
+runAllTests()

test/Runtime/weak-reference-racetests.swift

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+// RUN: %target-run-simple-swift
+// REQUIRES: executable_test
+
+import StdlibUnittest
+
+// Also import modules which are used by StdlibUnittest internally. This
+// workaround is needed to link all required libraries in case we compile
+// StdlibUnittest with -sil-serialize-all.
+import SwiftPrivate
+#if _runtime(_ObjC)
+import ObjectiveC
+#endif
+
+let iterations = 1_000
+
+class Thing {}
+
+class WBox<T: AnyObject> {
+  weak var wref: T?
+  init(_ ref: T) { self.wref = ref }
+  init() { self.wref = nil }
+}
+
+class WeakReferenceRaceData {
+  let closure: () -> Void
+  init(_ closure: () -> Void) {
+    self.closure = closure
+  }
+}
+
+protocol WeakReferenceRaceTest: RaceTestWithPerTrialData {
+  associatedtype RaceData = WeakReferenceRaceData
+  associatedtype ThreadLocalData = Void
+  associatedtype Observation = Observation1UInt
+}
+
+extension WeakReferenceRaceTest {
+  func makeThreadLocalData() -> Void {
+    return ()
+  }
+
+  func thread1(
+    _ raceData: WeakReferenceRaceData,
+    _ threadLocalData: inout Void
+    ) -> Observation1UInt {
+    raceData.closure()
+    // The trial succeeds by completing without crashing
+    return Observation1UInt(0)
+  }
+
+  func evaluateObservations(
+    _ observations: [Observation1UInt],
+    _ sink: (RaceTestObservationEvaluation) -> Void
+    ) {
+    sink(evaluateObservationsAllEqual(observations))
+  }
+}
+
+let WeakReferenceRaceTests = TestSuite("WeakReferenceRaceTests")
+
+struct RaceTest_instancePropertyCopy: WeakReferenceRaceTest {
+  func makeRaceData() -> WeakReferenceRaceData {
+    // Capture a weak reference via its container object
+    // "https://bugs.swift.org/browse/SR-192"
+    let box = WBox(Thing())
+    return WeakReferenceRaceData {
+      let nbox = WBox<Thing>()
+      nbox.wref = box.wref
+      _blackHole(nbox)
+    }
+  }
+}
+
+WeakReferenceRaceTests.test("class instance property [SR-192] (copy)") {
+  runRaceTest(RaceTest_instancePropertyCopy.self, trials: iterations)
+}
+
+struct RaceTest_instancePropertyLoad: WeakReferenceRaceTest {
+  func makeRaceData() -> WeakReferenceRaceData {
+    // Capture a weak reference via its container object
+    // "https://bugs.swift.org/browse/SR-192"
+    let box = WBox(Thing())
+    return WeakReferenceRaceData {
+      if let ref = box.wref {
+        _blackHole(ref)
+      }
+    }
+  }
+}
+
+WeakReferenceRaceTests.test("class instance property [SR-192] (load)") {
+  runRaceTest(RaceTest_instancePropertyLoad.self, trials: iterations)
+}
+
+struct RaceTest_directCaptureCopy: WeakReferenceRaceTest {
+  func makeRaceData() -> WeakReferenceRaceData {
+    weak var wref = Thing()
+    return WeakReferenceRaceData {
+      let nbox = WBox<Thing>()
+      nbox.wref = wref
+      _blackHole(nbox)
+    }
+  }
+}
+
+WeakReferenceRaceTests.test("direct capture (copy)") {
+  runRaceTest(RaceTest_directCaptureCopy.self, trials: iterations)
+}
+
+struct RaceTest_directCaptureLoad: WeakReferenceRaceTest {
+  func makeRaceData() -> WeakReferenceRaceData {
+    weak var wref = Thing()
+    return WeakReferenceRaceData {
+      let nbox = WBox<Thing>()
+      nbox.wref = wref
+      _blackHole(nbox)
+    }
+  }
+}
+
+WeakReferenceRaceTests.test("direct capture (load)") {
+  runRaceTest(RaceTest_directCaptureLoad.self, trials: iterations)
+}
+
+runAllTests()