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..7a621dce2cb37c8e4301dc47bb3501da0b26976d 100644
--- a/webrtc/base/bind_unittest.cc
+++ b/webrtc/base/bind_unittest.cc
@@ -11,6 +11,8 @@
 #include "webrtc/base/bind.h"
 #include "webrtc/base/gunit.h"
 
+#include "webrtc/base/refcount.h"
+
 namespace rtc {
 
 namespace {
@@ -26,12 +28,67 @@ struct MethodBindTester {
   mutable int call_count;
 };
 
+struct A { int dummy; };
+struct B: public RefCountInterface { int dummy; };
+struct C: public A, B {};
+struct D {
+  int AddRef();
+};
+struct E: public D {
+  int Release();
+};
+struct F {
+  void AddRef();
+  void Release();
+};
+
+class LifeTimeCheck : public RefCountInterface {
+ public:
+  LifeTimeCheck(bool* has_died) : has_died_(has_died), is_ok_to_die_(false) {}
+  ~LifeTimeCheck() {
+    EXPECT_TRUE(is_ok_to_die_);
+    *has_died_ = true;
+  }
+  void PrepareToDie() { is_ok_to_die_ = true; }
+  void NullaryVoid() {}
+
+ private:
+  bool* const has_died_;
+  bool is_ok_to_die_;
+};
+
 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(D);
+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(E);
+EXPECT_IS_CAPTURED_AS_SCOPED_REFPTR(F);
+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 +121,49 @@ 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 object_has_died = false;
+  scoped_refptr<LifeTimeCheck> object =
+      new RefCountedObject<LifeTimeCheck>(&object_has_died);
+  {
+    auto functor = Bind(&LifeTimeCheck::PrepareToDie, object.get());
+    object = nullptr;
+    EXPECT_FALSE(object_has_died);
+    // Run prepare to die via functor.
+    functor();
+  }
+  EXPECT_TRUE(object_has_died);
+}
+
+// Test Bind where method object implements RefCountInterface and is passed as a
+// scoped_refptr<>.
+TEST(BindTest, CaptureScopedRefPtrAsScopedRefPtr) {
+  bool object_has_died = false;
+  scoped_refptr<LifeTimeCheck> object =
+      new RefCountedObject<LifeTimeCheck>(&object_has_died);
+  {
+    auto functor = Bind(&LifeTimeCheck::PrepareToDie, object);
+    object = nullptr;
+    EXPECT_FALSE(object_has_died);
+    // Run prepare to die via functor.
+    functor();
+  }
+  EXPECT_TRUE(object_has_died);
+}
+
+// Test Bind where method object is captured as scoped_refptr<> and the functor
+// dies while there are references left.
+TEST(BindTest, FunctorReleasesObjectOnDestruction) {
+  bool object_has_died = false;
+  scoped_refptr<LifeTimeCheck> object =
+      new RefCountedObject<LifeTimeCheck>(&object_has_died);
+  Bind(&LifeTimeCheck::NullaryVoid, object.get())();
+  EXPECT_FALSE(object_has_died);
+  object->PrepareToDie();
+  object = nullptr;
+  EXPECT_TRUE(object_has_died);
+}
+
 }  // namespace rtc