Over in bug 935778, I'm making RefCounted opt into the leak detection
facilities of XPCOM. This means that soon you will have to consider the
following before using RefCounted:
1. You should make sure that the consumers of your code either all live
in libxul or they all live outside of it. If they live in libxul, you
will get leak detection support. If they live elsewhere (such as js, or
gkmedias), you will not get leak checking. If some consumers live in
libxul and some live outside of it, you should *not* use RefCounted.
2. For every class that inherits from RefCounted, you need to add a
macro to your class, such as:
class Foo : public mozilla::RefCounted<Foo>
{
public:
// This should go in the public section
MOZ_DECLARE_REFCOUNTED_TYPENAME(Foo)
// ...
};
If you have other classes derived this class, you need to use an
alternate macro:
class Base : public mozilla::RefCounted<Base>
{
public:
MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(Base)
};
class Derived : public Base
{
public:
MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(Derived)
};
If you forget to add these macros, your code will not compile. If you
forget to use the virtual macros, you will confuse the leak detector and
will need to debug it.
3. For every class that inherits from mozilla::SupportsWeakPtr, you will
need to add macros similar to the above.
Please note that even with these changes, the RefCounted class is still
not on feature parity with NS_INLINE_DECL_REFCOUNTING in that it doesn't
include thread safety assertions, so it won't detect those types of bugs
for you. Therefore, I would like to *discourage* everyone from using
this class until somebody adds that feature to RefCounted. And now that
you will need to use macros with RefCounted, using it is actually harder
and less beautiful than NS_INLINE_DECL_REFCOUNTING.
Cheers,
Ehsan
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