juce_Atomic.h

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/*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited
 
   JUCE is an open source library subject to commercial or open-source
   licensing.
 
   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.
 
   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.
 
  ==============================================================================
*/
 
namespace juce
{
 
#ifndef DOXYGEN
 namespace AtomicHelpers
 {
     template <typename T> struct DiffTypeHelper     { using Type = T; };
     template <typename T> struct DiffTypeHelper<T*> { using Type = std::ptrdiff_t; };
 }
#endif
 
//==============================================================================
template <typename Type>
struct Atomic  final
{
    using DiffType = typename AtomicHelpers::DiffTypeHelper<Type>::Type;

    Atomic() noexcept  : value (Type()) {}

    Atomic (Type initialValue) noexcept  : value (initialValue) {}

    Atomic (const Atomic& other) noexcept  : value (other.get()) {}

    ~Atomic() noexcept
    {
       #if __cpp_lib_atomic_is_always_lock_free
        static_assert (std::atomic<Type>::is_always_lock_free,
                       "This class can only be used for lock-free types");
       #endif
    }

    Type get() const noexcept               { return value.load(); }

    void set (Type newValue) noexcept       { value = newValue; }

    Type exchange (Type newValue) noexcept  { return value.exchange (newValue); }

    bool compareAndSetBool (Type newValue, Type valueToCompare) noexcept
    {
        return value.compare_exchange_strong (valueToCompare, newValue);
    }

    Atomic<Type>& operator= (const Atomic& other) noexcept
    {
        value = other.value.load();
        return *this;
    }

    Atomic<Type>& operator= (Type newValue) noexcept
    {
        value = newValue;
        return *this;
    }

    Type operator+= (DiffType amountToAdd) noexcept { return value += amountToAdd; }

    Type operator-= (DiffType amountToSubtract) noexcept { return value -= amountToSubtract; }

    Type operator++() noexcept { return ++value; }

    Type operator--() noexcept { return --value; }

    void memoryBarrier() noexcept          { atomic_thread_fence (std::memory_order_seq_cst); }

    std::atomic<Type> value;
 
    //==============================================================================
   #ifndef DOXYGEN
    [[deprecated ("This method has been deprecated as there is no equivalent method in "
                 "std::atomic. Use compareAndSetBool instead.")]]
    Type compareAndSetValue (Type, Type) noexcept;
   #endif
};
 
} // namespace juce