rtc::Bind: Capture method objects as scoped_refptr if they are ref counted

webrtc/base/bind_unittest.cc

Index: webrtc/base/bind_unittest.cc
diff --git a/webrtc/base/bind_unittest.cc b/webrtc/base/bind_unittest.cc
index ed8dd5cf2d226a93b24512069bc9324aa9c91619..707b8d4935dc6922711a5cbebcd709e56f212a7b 100644
--- a/webrtc/base/bind_unittest.cc
+++ b/webrtc/base/bind_unittest.cc
@@ -26,12 +26,54 @@ struct MethodBindTester {
   mutable int call_count;
 };
 
+struct A { int dummy; };
+struct B: public RefCountInterface { int dummy; };
+struct C: public A, B {};
+
+class LifeTimeCheck : public RefCountInterface {
+ public:
+  LifeTimeCheck(bool* hasDied) : hasDied_(hasDied), isOkToDie(false) {}
+  ~LifeTimeCheck() {
+    EXPECT_TRUE(isOkToDie);
+    *hasDied_ = true;
+  }
+  void PrepareToDie() { isOkToDie = true; }
+  void NullaryVoid() {}
+
+ private:
+  bool* const hasDied_;
+  bool isOkToDie;
+};
+
 int Return42() { return 42; }
 int Negate(int a) { return -a; }
 int Multiply(int a, int b) { return a * b; }
 
 }  // namespace
 
+// Try to catch any problem with scoped_refptr type deduction in rtc::Bind at
+// compile time.
+#define EXPECT_IS_CAPTURED_AS_PTR(T)                              \
+  static_assert(is_same<detail::PointerType<T>::type, T*>::value, \
+                "PointerType")
+#define EXPECT_IS_CAPTURED_AS_SCOPED_REFPTR(T)                        \
+  static_assert(                                                      \
+      is_same<detail::PointerType<T>::type, scoped_refptr<T>>::value, \
+      "PointerType")
+
+EXPECT_IS_CAPTURED_AS_PTR(void);
+EXPECT_IS_CAPTURED_AS_PTR(int);
+EXPECT_IS_CAPTURED_AS_PTR(double);
+EXPECT_IS_CAPTURED_AS_PTR(A);
+EXPECT_IS_CAPTURED_AS_PTR(RefCountInterface*);
+
+EXPECT_IS_CAPTURED_AS_SCOPED_REFPTR(RefCountInterface);
+EXPECT_IS_CAPTURED_AS_SCOPED_REFPTR(B);
+EXPECT_IS_CAPTURED_AS_SCOPED_REFPTR(C);
+EXPECT_IS_CAPTURED_AS_SCOPED_REFPTR(RefCountedObject<RefCountInterface>);
+EXPECT_IS_CAPTURED_AS_SCOPED_REFPTR(RefCountedObject<B>);
+EXPECT_IS_CAPTURED_AS_SCOPED_REFPTR(RefCountedObject<C>);
+
 TEST(BindTest, BindToMethod) {
   MethodBindTester object = {0};
   EXPECT_EQ(0, object.call_count);
@@ -64,4 +106,51 @@ TEST(BindTest, BindToFunction) {
   EXPECT_EQ(56, Bind(&Multiply, 8, 7)());
 }
 
+// Test Bind where method object implements RefCountInterface and is passed as a
+// pointer.
+TEST(BindTest, CapturePointerAsScopedRefPtr) {
+  bool objectHasDied = false;
+  scoped_refptr<LifeTimeCheck> object =
+      new RefCountedObject<LifeTimeCheck>(&objectHasDied);
+  {
+    MethodFunctor0<LifeTimeCheck, void (LifeTimeCheck::*)(), void> functor =
+        Bind(&LifeTimeCheck::PrepareToDie, object.get());
+    object = nullptr;
+    EXPECT_FALSE(objectHasDied);
+    // Run prepare to die via functor.
+    functor();
+  }
+  EXPECT_TRUE(objectHasDied);
+}
+
+// Test Bind where method object implements RefCountInterface and is passed as a
+// scoped_refptr<>.
+TEST(BindTest, CaptureScopedRefPtrAsScopedRefPtr) {
+  bool objectHasDied = false;
+  scoped_refptr<LifeTimeCheck> object =
+      new RefCountedObject<LifeTimeCheck>(&objectHasDied);
+  {
+    MethodFunctor0<LifeTimeCheck, void (LifeTimeCheck::*)(), void> functor =
+        Bind(&LifeTimeCheck::PrepareToDie, object);
+    object = nullptr;
+    EXPECT_FALSE(objectHasDied);
+    // Run prepare to die via functor.
+    functor();
+  }
+  EXPECT_TRUE(objectHasDied);
+}
+
+// Test Bind where method object is captured as scoped_refptr<> and the functor
+// dies while there are references left.
+TEST(BindTest, FunctorReleasesObjectOnDestruction) {
+  bool objectHasDied = false;
+  scoped_refptr<LifeTimeCheck> object =
+      new RefCountedObject<LifeTimeCheck>(&objectHasDied);
+  Bind(&LifeTimeCheck::NullaryVoid, object.get())();
+  EXPECT_FALSE(objectHasDied);
+  object->PrepareToDie();
+  object = nullptr;
+  EXPECT_TRUE(objectHasDied);
+}
+
 }  // namespace rtc