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/* -*- 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;
bool IsAlive() const override { return mReferent != nullptr; }
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;
}
}
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