1 //===----------------------------------------------------------------------===//
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 _LIBCPP_SUPPRESS_DEPRECATED_PUSH
12
13 #ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
14 # include <atomic>
15 #elif !defined(_LIBCPP_HAS_NO_THREADS)
16 # include <mutex>
17 # if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
18 # pragma comment(lib, "pthread")
19 # endif
20 #endif
21
22 _LIBCPP_BEGIN_NAMESPACE_LFTS_PMR
23
24 // memory_resource
25
26 //memory_resource::~memory_resource() {}
27
28 // new_delete_resource()
29
30 class _LIBCPP_TYPE_VIS __new_delete_memory_resource_imp
31 : public memory_resource
32 {
do_allocate(size_t size,size_t align)33 void *do_allocate(size_t size, size_t align) override {
34 #ifdef _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
35 if (__is_overaligned_for_new(align))
36 __throw_bad_alloc();
37 #endif
38 return _VSTD::__libcpp_allocate(size, align);
39 }
40
do_deallocate(void * p,size_t n,size_t align)41 void do_deallocate(void *p, size_t n, size_t align) override {
42 _VSTD::__libcpp_deallocate(p, n, align);
43 }
44
do_is_equal(memory_resource const & other) const45 bool do_is_equal(memory_resource const & other) const noexcept override
46 { return &other == this; }
47
48 public:
49 ~__new_delete_memory_resource_imp() override = default;
50 };
51
52 // null_memory_resource()
53
54 class _LIBCPP_TYPE_VIS __null_memory_resource_imp
55 : public memory_resource
56 {
57 public:
58 ~__null_memory_resource_imp() = default;
59
60 protected:
do_allocate(size_t,size_t)61 virtual void* do_allocate(size_t, size_t) {
62 __throw_bad_alloc();
63 }
do_deallocate(void *,size_t,size_t)64 virtual void do_deallocate(void *, size_t, size_t) {}
do_is_equal(memory_resource const & __other) const65 virtual bool do_is_equal(memory_resource const & __other) const noexcept
66 { return &__other == this; }
67 };
68
69 namespace {
70
71 union ResourceInitHelper {
72 struct {
73 __new_delete_memory_resource_imp new_delete_res;
74 __null_memory_resource_imp null_res;
75 } resources;
76 char dummy;
ResourceInitHelper()77 _LIBCPP_CONSTEXPR_SINCE_CXX14 ResourceInitHelper() : resources() {}
~ResourceInitHelper()78 ~ResourceInitHelper() {}
79 };
80
81 // Pretend we're inside a system header so the compiler doesn't flag the use of the init_priority
82 // attribute with a value that's reserved for the implementation (we're the implementation).
83 #include "memory_resource_init_helper.h"
84
85 } // end namespace
86
87
new_delete_resource()88 memory_resource * new_delete_resource() noexcept {
89 return &res_init.resources.new_delete_res;
90 }
91
null_memory_resource()92 memory_resource * null_memory_resource() noexcept {
93 return &res_init.resources.null_res;
94 }
95
96 // default_memory_resource()
97
98 static memory_resource *
__default_memory_resource(bool set=false,memory_resource * new_res=nullptr)99 __default_memory_resource(bool set = false, memory_resource * new_res = nullptr) noexcept
100 {
101 #ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
102 static constinit atomic<memory_resource*> __res{&res_init.resources.new_delete_res};
103 if (set) {
104 new_res = new_res ? new_res : new_delete_resource();
105 // TODO: Can a weaker ordering be used?
106 return _VSTD::atomic_exchange_explicit(
107 &__res, new_res, memory_order_acq_rel);
108 }
109 else {
110 return _VSTD::atomic_load_explicit(
111 &__res, memory_order_acquire);
112 }
113 #elif !defined(_LIBCPP_HAS_NO_THREADS)
114 static constinit memory_resource *res = &res_init.resources.new_delete_res;
115 static mutex res_lock;
116 if (set) {
117 new_res = new_res ? new_res : new_delete_resource();
118 lock_guard<mutex> guard(res_lock);
119 memory_resource * old_res = res;
120 res = new_res;
121 return old_res;
122 } else {
123 lock_guard<mutex> guard(res_lock);
124 return res;
125 }
126 #else
127 static constinit memory_resource *res = &res_init.resources.new_delete_res;
128 if (set) {
129 new_res = new_res ? new_res : new_delete_resource();
130 memory_resource * old_res = res;
131 res = new_res;
132 return old_res;
133 } else {
134 return res;
135 }
136 #endif
137 }
138
get_default_resource()139 memory_resource * get_default_resource() noexcept
140 {
141 return __default_memory_resource();
142 }
143
set_default_resource(memory_resource * __new_res)144 memory_resource * set_default_resource(memory_resource * __new_res) noexcept
145 {
146 return __default_memory_resource(true, __new_res);
147 }
148
149 _LIBCPP_END_NAMESPACE_LFTS_PMR
150