gecko-dev/ipc/mscom/Aggregation.h
Aaron Klotz f3fa5ee8d2 Bug 1303060: ipc/mscom changes for handler and payload support; r=jimm
MozReview-Commit-ID: 13NFW1pgxix

--HG--
extra : rebase_source : 18cc11d4c1dc62bc0ee428608f6cb57e32c4d0af
2017-02-17 17:30:03 -07:00

100 lines
2.7 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_mscom_Aggregation_h
#define mozilla_mscom_Aggregation_h
#include "mozilla/Attributes.h"
#include <stddef.h>
#include <unknwn.h>
namespace mozilla {
namespace mscom {
/**
* This is used for stabilizing a COM object's reference count during
* construction when that object aggregates other objects. Since the aggregated
* object(s) may AddRef() or Release(), we need to artifically boost the
* refcount to prevent premature destruction. Note that we increment/decrement
* instead of AddRef()/Release() in this class because we want to adjust the
* refcount without causing any other side effects (like object destruction).
*/
template <typename RefCntT>
class MOZ_RAII StabilizedRefCount
{
public:
explicit StabilizedRefCount(RefCntT& aRefCnt)
: mRefCnt(aRefCnt)
{
++aRefCnt;
}
~StabilizedRefCount()
{
--mRefCnt;
}
StabilizedRefCount(const StabilizedRefCount&) = delete;
StabilizedRefCount(StabilizedRefCount&&) = delete;
StabilizedRefCount& operator=(const StabilizedRefCount&) = delete;
StabilizedRefCount& operator=(StabilizedRefCount&&) = delete;
private:
RefCntT& mRefCnt;
};
namespace detail {
template <typename T>
class InternalUnknown : public IUnknown
{
public:
STDMETHODIMP QueryInterface(REFIID aIid, void** aOutInterface) override
{
return This()->InternalQueryInterface(aIid, aOutInterface);
}
STDMETHODIMP_(ULONG) AddRef() override
{
return This()->InternalAddRef();
}
STDMETHODIMP_(ULONG) Release() override
{
return This()->InternalRelease();
}
private:
T* This()
{
return reinterpret_cast<T*>(reinterpret_cast<char*>(this) -
offsetof(T, mInternalUnknown));
}
};
} // namespace detail
} // namespace mscom
} // namespace mozilla
#define DECLARE_AGGREGATABLE(Type) \
public: \
STDMETHODIMP QueryInterface(REFIID riid, void** ppv) override \
{ return mOuter->QueryInterface(riid, ppv); } \
STDMETHODIMP_(ULONG) AddRef() override \
{ return mOuter->AddRef(); } \
STDMETHODIMP_(ULONG) Release() override \
{ return mOuter->Release(); } \
protected: \
STDMETHODIMP InternalQueryInterface(REFIID riid, void** ppv); \
STDMETHODIMP_(ULONG) InternalAddRef(); \
STDMETHODIMP_(ULONG) InternalRelease(); \
friend class mozilla::mscom::detail::InternalUnknown<Type>; \
mozilla::mscom::detail::InternalUnknown<Type> mInternalUnknown
#endif // mozilla_mscom_Aggregation_h