gc_heap.hpp

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//
// immer: immutable data structures for C++
// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
//
// This software is distributed under the Boost Software License, Version 1.0.
// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
//

#pragma once

#include <immer/config.hpp>
#include <immer/heap/tags.hpp>

#if IMMER_HAS_LIBGC
#include <gc/gc.h>
#else
#error "Using garbage collection requires libgc"
#endif

#include <cstdlib>
#include <memory>

namespace immer {

#ifdef __APPLE__
#define IMMER_GC_REQUIRE_INIT 1
#else
#define IMMER_GC_REQUIRE_INIT 0
#endif

#if IMMER_GC_REQUIRE_INIT

namespace detail {

template <int Dummy=0>
struct gc_initializer
{
    gc_initializer() { GC_init(); }
    static gc_initializer init;
};

template <int D>
gc_initializer<D> gc_initializer<D>::init {};

inline void gc_initializer_guard()
{
    static gc_initializer<> init_ = gc_initializer<>::init;
    (void) init_;
}

} // namespace detail

#define IMMER_GC_INIT_GUARD_ ::immer::detail::gc_initializer_guard()

#else

#define IMMER_GC_INIT_GUARD_

#endif // IMMER_GC_REQUIRE_INIT

class gc_heap
{
public:
    static void* allocate(std::size_t n)
    {
        IMMER_GC_INIT_GUARD_;
        auto p = GC_malloc(n);
        if (IMMER_UNLIKELY(!p))
            throw std::bad_alloc{};
        return p;
    }

    static void* allocate(std::size_t n, norefs_tag)
    {
        IMMER_GC_INIT_GUARD_;
        auto p = GC_malloc_atomic(n);
        if (IMMER_UNLIKELY(!p))
            throw std::bad_alloc{};
        return p;
    }

    static void deallocate(std::size_t, void* data)
    {
        GC_free(data);
    }

    static void deallocate(std::size_t, void* data, norefs_tag)
    {
        GC_free(data);
    }
};

} // namespace immer