src/dawn/native/RefCountedWithExternalCount.h

// Copyright 2022 The Dawn & Tint Authors
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#ifndef SRC_DAWN_NATIVE_REFCOUNTEDWITHEXTERNALCOUNT_H_
#define SRC_DAWN_NATIVE_REFCOUNTEDWITHEXTERNALCOUNT_H_

#include "dawn/common/RefCounted.h"

namespace dawn::native {

// RecCountedWithExternalCount is a version of RefCounted which tracks a separate
// refcount for calls to APIReference/APIRelease (refs added/removed by the application).
// The external refcount starts at 1, and the total refcount starts at 1 - i.e. the first
// ref is the external ref.
// Then, when the external refcount drops to zero, WillDropLastExternalRef is called.
// The derived class should override the behavior of WillDropLastExternalRef.
class RefCountedWithExternalCount : private RefCounted {
  public:
    using RefCounted::RefCounted;
    using RefCounted::Reference;
    using RefCounted::Release;

    void APIReference();
    void APIRelease();

  protected:
    using RefCounted::DeleteThis;

  private:
    virtual void WillDropLastExternalRef() = 0;

    RefCount mExternalRefCount;
};

}  // namespace dawn::native

#endif  // SRC_DAWN_NATIVE_REFCOUNTEDWITHEXTERNALCOUNT_H_