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//===------------------------ memory_resource.cpp -------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "experimental/memory_resource"
#ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
#include "atomic"
#elif !defined(_LIBCPP_HAS_NO_THREADS)
#include "mutex"
#endif
_LIBCPP_BEGIN_NAMESPACE_LFTS_PMR
// memory_resource
//memory_resource::~memory_resource() {}
// new_delete_resource()
class _LIBCPP_TYPE_VIS __new_delete_memory_resource_imp
: public memory_resource
{
public:
~__new_delete_memory_resource_imp() = default;
protected:
virtual void* do_allocate(size_t __size, size_t __align)
{ return _VSTD::__libcpp_allocate(__size, __align); /* FIXME */}
virtual void do_deallocate(void* __p, size_t __n, size_t __align) {
_VSTD::__libcpp_deallocate(__p, __n, __align); /* FIXME */
}
virtual bool do_is_equal(memory_resource const & __other) const _NOEXCEPT
{ return &__other == this; }
};
// null_memory_resource()
class _LIBCPP_TYPE_VIS __null_memory_resource_imp
: public memory_resource
{
public:
~__null_memory_resource_imp() = default;
protected:
virtual void* do_allocate(size_t, size_t) {
__throw_bad_alloc();
}
virtual void do_deallocate(void *, size_t, size_t) {}
virtual bool do_is_equal(memory_resource const & __other) const _NOEXCEPT
{ return &__other == this; }
};
namespace {
union ResourceInitHelper {
struct {
__new_delete_memory_resource_imp new_delete_res;
__null_memory_resource_imp null_res;
} resources;
char dummy;
_LIBCPP_CONSTEXPR_AFTER_CXX11 ResourceInitHelper() : resources() {}
~ResourceInitHelper() {}
};
// Detect if the init_priority attribute is supported.
#if (defined(_LIBCPP_COMPILER_GCC) && defined(__APPLE__)) \
|| defined(_LIBCPP_COMPILER_MSVC)
// GCC on Apple doesn't support the init priority attribute,
// and MSVC doesn't support any GCC attributes.
# define _LIBCPP_INIT_PRIORITY_MAX
#else
# define _LIBCPP_INIT_PRIORITY_MAX __attribute__((init_priority(101)))
#endif
// When compiled in C++14 this initialization should be a constant expression.
// Only in C++11 is "init_priority" needed to ensure initialization order.
#if _LIBCPP_STD_VER > 11
_LIBCPP_SAFE_STATIC
#endif
ResourceInitHelper res_init _LIBCPP_INIT_PRIORITY_MAX;
} // end namespace
memory_resource * new_delete_resource() _NOEXCEPT {
return &res_init.resources.new_delete_res;
}
memory_resource * null_memory_resource() _NOEXCEPT {
return &res_init.resources.null_res;
}
// default_memory_resource()
static memory_resource *
__default_memory_resource(bool set = false, memory_resource * new_res = nullptr) _NOEXCEPT
{
#ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
_LIBCPP_SAFE_STATIC static atomic<memory_resource*> __res =
ATOMIC_VAR_INIT(&res_init.resources.new_delete_res);
if (set) {
new_res = new_res ? new_res : new_delete_resource();
// TODO: Can a weaker ordering be used?
return _VSTD::atomic_exchange_explicit(
&__res, new_res, memory_order::memory_order_acq_rel);
}
else {
return _VSTD::atomic_load_explicit(
&__res, memory_order::memory_order_acquire);
}
#elif !defined(_LIBCPP_HAS_NO_THREADS)
_LIBCPP_SAFE_STATIC static memory_resource * res = &res_init.resources.new_delete_res;
static mutex res_lock;
if (set) {
new_res = new_res ? new_res : new_delete_resource();
lock_guard<mutex> guard(res_lock);
memory_resource * old_res = res;
res = new_res;
return old_res;
} else {
lock_guard<mutex> guard(res_lock);
return res;
}
#else
_LIBCPP_SAFE_STATIC static memory_resource* res = &res_init.resources.new_delete_res;
if (set) {
new_res = new_res ? new_res : new_delete_resource();
memory_resource * old_res = res;
res = new_res;
return old_res;
} else {
return res;
}
#endif
}
memory_resource * get_default_resource() _NOEXCEPT
{
return __default_memory_resource();
}
memory_resource * set_default_resource(memory_resource * __new_res) _NOEXCEPT
{
return __default_memory_resource(true, __new_res);
}
_LIBCPP_END_NAMESPACE_LFTS_PMR
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