1 //===------------------------ memory_resource.cpp -------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "experimental/memory_resource"
10
11 #ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
12 #include "atomic"
13 #elif !defined(_LIBCPP_HAS_NO_THREADS)
14 #include "mutex"
15 #if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
16 #pragma comment(lib, "pthread")
17 #endif
18 #endif
19
20 _LIBCPP_BEGIN_NAMESPACE_LFTS_PMR
21
22 // memory_resource
23
24 //memory_resource::~memory_resource() {}
25
26 // new_delete_resource()
27
28 class _LIBCPP_TYPE_VIS __new_delete_memory_resource_imp
29 : public memory_resource
30 {
do_allocate(size_t size,size_t align)31 void *do_allocate(size_t size, size_t align) override {
32 #ifdef _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
33 if (__is_overaligned_for_new(align))
34 __throw_bad_alloc();
35 #endif
36 return _VSTD::__libcpp_allocate(size, align);
37 }
38
do_deallocate(void * p,size_t n,size_t align)39 void do_deallocate(void *p, size_t n, size_t align) override {
40 _VSTD::__libcpp_deallocate(p, n, align);
41 }
42
do_is_equal(memory_resource const & other) const43 bool do_is_equal(memory_resource const & other) const noexcept override
44 { return &other == this; }
45
46 public:
47 ~__new_delete_memory_resource_imp() override = default;
48 };
49
50 // null_memory_resource()
51
52 class _LIBCPP_TYPE_VIS __null_memory_resource_imp
53 : public memory_resource
54 {
55 public:
56 ~__null_memory_resource_imp() = default;
57
58 protected:
do_allocate(size_t,size_t)59 virtual void* do_allocate(size_t, size_t) {
60 __throw_bad_alloc();
61 }
do_deallocate(void *,size_t,size_t)62 virtual void do_deallocate(void *, size_t, size_t) {}
do_is_equal(memory_resource const & __other) const63 virtual bool do_is_equal(memory_resource const & __other) const noexcept
64 { return &__other == this; }
65 };
66
67 namespace {
68
69 union ResourceInitHelper {
70 struct {
71 __new_delete_memory_resource_imp new_delete_res;
72 __null_memory_resource_imp null_res;
73 } resources;
74 char dummy;
ResourceInitHelper()75 _LIBCPP_CONSTEXPR_AFTER_CXX11 ResourceInitHelper() : resources() {}
~ResourceInitHelper()76 ~ResourceInitHelper() {}
77 };
78
79 _LIBCPP_SAFE_STATIC ResourceInitHelper res_init _LIBCPP_INIT_PRIORITY_MAX;
80
81 } // end namespace
82
83
new_delete_resource()84 memory_resource * new_delete_resource() noexcept {
85 return &res_init.resources.new_delete_res;
86 }
87
null_memory_resource()88 memory_resource * null_memory_resource() noexcept {
89 return &res_init.resources.null_res;
90 }
91
92 // default_memory_resource()
93
94 static memory_resource *
__default_memory_resource(bool set=false,memory_resource * new_res=nullptr)95 __default_memory_resource(bool set = false, memory_resource * new_res = nullptr) noexcept
96 {
97 #ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
98 _LIBCPP_SAFE_STATIC static atomic<memory_resource*> __res =
99 ATOMIC_VAR_INIT(&res_init.resources.new_delete_res);
100 if (set) {
101 new_res = new_res ? new_res : new_delete_resource();
102 // TODO: Can a weaker ordering be used?
103 return _VSTD::atomic_exchange_explicit(
104 &__res, new_res, memory_order_acq_rel);
105 }
106 else {
107 return _VSTD::atomic_load_explicit(
108 &__res, memory_order_acquire);
109 }
110 #elif !defined(_LIBCPP_HAS_NO_THREADS)
111 _LIBCPP_SAFE_STATIC static memory_resource * res = &res_init.resources.new_delete_res;
112 static mutex res_lock;
113 if (set) {
114 new_res = new_res ? new_res : new_delete_resource();
115 lock_guard<mutex> guard(res_lock);
116 memory_resource * old_res = res;
117 res = new_res;
118 return old_res;
119 } else {
120 lock_guard<mutex> guard(res_lock);
121 return res;
122 }
123 #else
124 _LIBCPP_SAFE_STATIC static memory_resource* res = &res_init.resources.new_delete_res;
125 if (set) {
126 new_res = new_res ? new_res : new_delete_resource();
127 memory_resource * old_res = res;
128 res = new_res;
129 return old_res;
130 } else {
131 return res;
132 }
133 #endif
134 }
135
get_default_resource()136 memory_resource * get_default_resource() noexcept
137 {
138 return __default_memory_resource();
139 }
140
set_default_resource(memory_resource * __new_res)141 memory_resource * set_default_resource(memory_resource * __new_res) noexcept
142 {
143 return __default_memory_resource(true, __new_res);
144 }
145
146 _LIBCPP_END_NAMESPACE_LFTS_PMR
147