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// Copyright 2022 The Dawn & Tint Authors
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef SRC_DAWN_NATIVE_REFCOUNTEDWITHEXTERNALCOUNT_H_
#define SRC_DAWN_NATIVE_REFCOUNTEDWITHEXTERNALCOUNT_H_
#include "dawn/common/RefCounted.h"
namespace dawn::native {
// RecCountedWithExternalCountBase is a version of RefCounted which tracks a separate
// refcount for calls to APIAddRef/APIRelease (refs added/removed by the application).
// The external refcount starts at 0, and the total refcount starts at 1 - i.e. the first
// ref isn't an external ref.
// When the external refcount drops to zero, WillDropLastExternalRef is called. and it can be called
// more than once.
// The derived class should override the behavior of WillDropLastExternalRef.
template <typename T>
class RefCountedWithExternalCountBase : public T {
public:
static constexpr bool HasExternalRefCount = true;
using T::AddRef;
using T::Release;
using T::T;
void APIAddRef() {
IncrementExternalRefCount();
T::APIAddRef();
}
void APIRelease() {
if (mExternalRefCount.Decrement()) {
WillDropLastExternalRef();
}
T::Release();
}
void IncrementExternalRefCount() { mExternalRefCount.Increment(); }
uint64_t GetExternalRefCountForTesting() const {
return mExternalRefCount.GetValueForTesting();
}
protected:
using T::DeleteThis;
private:
virtual void WillDropLastExternalRef() = 0;
RefCount mExternalRefCount{/*initCount=*/0, /*payload=*/0};
};
using RefCountedWithExternalCount = RefCountedWithExternalCountBase<RefCounted>;
} // namespace dawn::native
#endif // SRC_DAWN_NATIVE_REFCOUNTEDWITHEXTERNALCOUNT_H_