104 lines
2.6 KiB
C++
104 lines
2.6 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_mscom_WeakRef_h
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#define mozilla_mscom_WeakRef_h
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#include <guiddef.h>
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#include <unknwn.h>
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#include "mozilla/Mutex.h"
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#include "nsTArray.h"
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/**
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* Thread-safe weak references for COM that works pre-Windows 8 and do not
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* require WinRT.
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*/
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namespace mozilla {
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namespace mscom {
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// {F841AEFA-064C-49A4-B73D-EBD14A90F012}
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DEFINE_GUID(IID_IWeakReference,
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0xf841aefa, 0x64c, 0x49a4, 0xb7, 0x3d, 0xeb, 0xd1, 0x4a, 0x90, 0xf0, 0x12);
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struct IWeakReference : public IUnknown
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{
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virtual STDMETHODIMP Resolve(REFIID aIid, void** aOutStringReference) = 0;
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};
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// {87611F0C-9BBB-4F78-9D43-CAC5AD432CA1}
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DEFINE_GUID(IID_IWeakReferenceSource,
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0x87611f0c, 0x9bbb, 0x4f78, 0x9d, 0x43, 0xca, 0xc5, 0xad, 0x43, 0x2c, 0xa1);
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struct IWeakReferenceSource : public IUnknown
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{
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virtual STDMETHODIMP GetWeakReference(IWeakReference** aOutWeakRef) = 0;
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};
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class WeakRef;
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class WeakReferenceSupport : public IWeakReferenceSource
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{
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public:
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enum class Flags
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{
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eNone = 0,
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eDestroyOnMainThread = 1
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};
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// IUnknown
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STDMETHODIMP QueryInterface(REFIID riid, void** ppv) override;
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STDMETHODIMP_(ULONG) AddRef() override;
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STDMETHODIMP_(ULONG) Release() override;
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// IWeakReferenceSource
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STDMETHODIMP GetWeakReference(IWeakReference** aOutWeakRef) override;
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protected:
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explicit WeakReferenceSupport(Flags aFlags);
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virtual ~WeakReferenceSupport();
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virtual HRESULT ThreadSafeQueryInterface(REFIID aIid,
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IUnknown** aOutInterface) = 0;
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private:
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void ClearWeakRefs();
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private:
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// Using a raw CRITICAL_SECTION here because it can be reentered
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CRITICAL_SECTION mCS;
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ULONG mRefCnt;
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nsTArray<WeakRef*> mWeakRefs;
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Flags mFlags;
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};
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class WeakRef : public IWeakReference
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{
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public:
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// IUnknown
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STDMETHODIMP QueryInterface(REFIID riid, void** ppv) override;
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STDMETHODIMP_(ULONG) AddRef() override;
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STDMETHODIMP_(ULONG) Release() override;
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// IWeakReference
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STDMETHODIMP Resolve(REFIID aIid, void** aOutStrongReference) override;
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explicit WeakRef(WeakReferenceSupport* aSupport);
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void Clear();
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private:
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ULONG mRefCnt;
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mozilla::Mutex mMutex; // Protects mSupport
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WeakReferenceSupport* mSupport;
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};
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} // namespace mscom
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} // namespace mozilla
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#endif // mozilla_mscom_WeakRef_h
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