CachedPointer.h

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// This file's extension implies that it's C, but it's really -*- C++ -*-.
/*
 * Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration.
 */
#ifndef CXXUTILS_CACHEDPOINTER_H
#define CXXUTILS_CACHEDPOINTER_H
 
 
#include <atomic>
#include <cassert>
 
 
#if ATOMIC_POINTER_LOCK_FREE != 2
# error Code assumes lock-free atomic pointers; see comments below.
#endif
 
 
namespace CxxUtils {
 
template <class T>
union CachedPointer
{
public:
  typedef const T* pointer_t;
 
 
  CachedPointer();
 
    
  CachedPointer (pointer_t elt);
 
 
  CachedPointer (const CachedPointer& other) noexcept;
 
  CachedPointer ( CachedPointer&& other) noexcept;
 
  CachedPointer& operator= (const CachedPointer& other);
 
 
  void set (pointer_t elt) const;
 
 
  void store (pointer_t elt);
 
  
  pointer_t get() const;
 
 
  const pointer_t* ptr() const;
 
 
private:
  mutable std::atomic<pointer_t> m_a;  
  pointer_t m_e;    
};
 
 
} // namespace CxxUtils
 
 
#include "CxxUtils/CachedPointer.icc"
 
 
#endif // not CXXUTILS_CACHEDPOINTER_H