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