/* -*- 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/. */ // nsWeakReference.cpp #include "mozilla/Attributes.h" #include "nsWeakReference.h" #include "nsCOMPtr.h" #include "nsDebug.h" #ifdef MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED #define MOZ_WEAKREF_DECL_OWNINGTHREAD nsAutoOwningThread _mWeakRefOwningThread; #define MOZ_WEAKREF_ASSERT_OWNINGTHREAD \ NS_CheckThreadSafe(_mWeakRefOwningThread.GetThread(), "nsWeakReference not thread-safe") #define MOZ_WEAKREF_ASSERT_OWNINGTHREAD_DELEGATED(that) \ NS_CheckThreadSafe((that)->_mWeakRefOwningThread.GetThread(), "nsWeakReference not thread-safe") #else #define MOZ_WEAKREF_DECL_OWNINGTHREAD #define MOZ_WEAKREF_ASSERT_OWNINGTHREAD do { } while (false) #define MOZ_WEAKREF_ASSERT_OWNINGTHREAD_DELEGATED(that) do { } while (false) #endif class nsWeakReference final : public nsIWeakReference { public: // nsISupports... NS_DECL_ISUPPORTS // nsIWeakReference... NS_DECL_NSIWEAKREFERENCE virtual size_t SizeOfOnlyThis(mozilla::MallocSizeOf aMallocSizeOf) const override; private: MOZ_WEAKREF_DECL_OWNINGTHREAD friend class nsSupportsWeakReference; explicit nsWeakReference(nsSupportsWeakReference* aReferent) : mReferent(aReferent) // ...I can only be constructed by an |nsSupportsWeakReference| { } ~nsWeakReference() // ...I will only be destroyed by calling |delete| myself. { MOZ_WEAKREF_ASSERT_OWNINGTHREAD; if (mReferent) { mReferent->NoticeProxyDestruction(); } } void NoticeReferentDestruction() // ...called (only) by an |nsSupportsWeakReference| from _its_ dtor. { MOZ_WEAKREF_ASSERT_OWNINGTHREAD; mReferent = nullptr; } nsSupportsWeakReference* MOZ_NON_OWNING_REF mReferent; }; nsresult nsQueryReferent::operator()(const nsIID& aIID, void** aAnswer) const { nsresult status; if (mWeakPtr) { if (NS_FAILED(status = mWeakPtr->QueryReferent(aIID, aAnswer))) { *aAnswer = 0; } } else { status = NS_ERROR_NULL_POINTER; } if (mErrorPtr) { *mErrorPtr = status; } return status; } nsIWeakReference* // or else |already_AddRefed<nsIWeakReference>| NS_GetWeakReference(nsISupports* aInstancePtr, nsresult* aErrorPtr) { nsresult status; nsIWeakReference* result = nullptr; if (aInstancePtr) { nsCOMPtr<nsISupportsWeakReference> factoryPtr = do_QueryInterface(aInstancePtr, &status); if (factoryPtr) { status = factoryPtr->GetWeakReference(&result); } // else, |status| has already been set by |do_QueryInterface| } else { status = NS_ERROR_NULL_POINTER; } if (aErrorPtr) { *aErrorPtr = status; } return result; } nsresult nsSupportsWeakReference::GetWeakReference(nsIWeakReference** aInstancePtr) { if (!aInstancePtr) { return NS_ERROR_NULL_POINTER; } if (!mProxy) { mProxy = new nsWeakReference(this); } else { MOZ_WEAKREF_ASSERT_OWNINGTHREAD_DELEGATED(mProxy); } *aInstancePtr = mProxy; nsresult status; if (!*aInstancePtr) { status = NS_ERROR_OUT_OF_MEMORY; } else { NS_ADDREF(*aInstancePtr); status = NS_OK; } return status; } NS_IMPL_ISUPPORTS(nsWeakReference, nsIWeakReference) NS_IMETHODIMP nsWeakReference::QueryReferent(const nsIID& aIID, void** aInstancePtr) { MOZ_WEAKREF_ASSERT_OWNINGTHREAD; return mReferent ? mReferent->QueryInterface(aIID, aInstancePtr) : NS_ERROR_NULL_POINTER; } size_t nsWeakReference::SizeOfOnlyThis(mozilla::MallocSizeOf aMallocSizeOf) const { return aMallocSizeOf(this); } void nsSupportsWeakReference::ClearWeakReferences() { if (mProxy) { mProxy->NoticeReferentDestruction(); mProxy = nullptr; } }