37 lines
856 B
C++
37 lines
856 B
C++
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//
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// immer: immutable data structures for C++
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// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
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//
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// This software is distributed under the Boost Software License, Version 1.0.
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// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
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//
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#pragma once
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#include <atomic>
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namespace immer {
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namespace detail {
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template <typename Deriv>
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struct ref_count_base
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{
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mutable std::atomic<int> ref_count { 0 };
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friend void intrusive_ptr_add_ref(const Deriv* x)
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{
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x->ref_count.fetch_add(1, std::memory_order_relaxed);
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}
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friend void intrusive_ptr_release(const Deriv* x)
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{
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if (x->ref_count.fetch_sub(1, std::memory_order_release) == 1) {
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std::atomic_thread_fence(std::memory_order_acquire);
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delete x;
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}
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}
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};
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} /* namespace detail */
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} /* namespace immer */
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