gecko-dev/gfx/layers/AtomicRefCountedWithFinalize.h

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2.9 KiB
C++

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* 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_ATOMICREFCOUNTEDWITHFINALIZE_H_
#define MOZILLA_ATOMICREFCOUNTEDWITHFINALIZE_H_
#include "mozilla/RefPtr.h"
#include "mozilla/NullPtr.h"
#include "mozilla/Likely.h"
#include "MainThreadUtils.h"
#include "base/message_loop.h"
#include "base/task.h"
namespace mozilla {
template<typename T>
class AtomicRefCountedWithFinalize
{
protected:
AtomicRefCountedWithFinalize()
: mRecycleCallback(nullptr)
, mRefCount(0)
, mMessageLoopToPostDestructionTo(nullptr)
{}
~AtomicRefCountedWithFinalize() {}
void SetMessageLoopToPostDestructionTo(MessageLoop* l) {
MOZ_ASSERT(NS_IsMainThread());
mMessageLoopToPostDestructionTo = l;
}
static void DestroyToBeCalledOnMainThread(T* ptr) {
MOZ_ASSERT(NS_IsMainThread());
delete ptr;
}
public:
void AddRef() {
MOZ_ASSERT(mRefCount >= 0);
++mRefCount;
}
void Release() {
MOZ_ASSERT(mRefCount > 0);
// Read mRecycleCallback early so that it does not get set to
// deleted memory, if the object is goes away.
RecycleCallback recycleCallback = mRecycleCallback;
int currCount = --mRefCount;
if (0 == currCount) {
// Recycle listeners must call ClearRecycleCallback
// before releasing their strong reference.
MOZ_ASSERT(mRecycleCallback == nullptr);
#ifdef DEBUG
mRefCount = detail::DEAD;
#endif
T* derived = static_cast<T*>(this);
derived->Finalize();
if (MOZ_LIKELY(!mMessageLoopToPostDestructionTo)) {
delete derived;
} else {
if (MOZ_LIKELY(NS_IsMainThread())) {
delete derived;
} else {
mMessageLoopToPostDestructionTo->PostTask(
FROM_HERE,
NewRunnableFunction(&DestroyToBeCalledOnMainThread, derived));
}
}
} else if (1 == currCount && recycleCallback) {
T* derived = static_cast<T*>(this);
recycleCallback(derived, mClosure);
}
}
typedef void (*RecycleCallback)(T* aObject, void* aClosure);
/**
* Set a callback responsible for recycling this object
* before it is finalized.
*/
void SetRecycleCallback(RecycleCallback aCallback, void* aClosure)
{
mRecycleCallback = aCallback;
mClosure = aClosure;
}
void ClearRecycleCallback() { SetRecycleCallback(nullptr, nullptr); }
bool HasRecycleCallback() const
{
return !!mRecycleCallback;
}
private:
RecycleCallback mRecycleCallback;
void *mClosure;
Atomic<int> mRefCount;
MessageLoop *mMessageLoopToPostDestructionTo;
};
}
#endif