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 // When compiled in C++14 this initialization should be a constant expression.
80 // Only in C++11 is "init_priority" needed to ensure initialization order.
81 #if _LIBCPP_STD_VER > 11
82 _LIBCPP_SAFE_STATIC
83 #endif
84 ResourceInitHelper res_init _LIBCPP_INIT_PRIORITY_MAX;
85
86 } // end namespace
87
88
new_delete_resource()89 memory_resource * new_delete_resource() _NOEXCEPT {
90 return &res_init.resources.new_delete_res;
91 }
92
null_memory_resource()93 memory_resource * null_memory_resource() _NOEXCEPT {
94 return &res_init.resources.null_res;
95 }
96
97 // default_memory_resource()
98
99 static memory_resource *
__default_memory_resource(bool set=false,memory_resource * new_res=nullptr)100 __default_memory_resource(bool set = false, memory_resource * new_res = nullptr) _NOEXCEPT
101 {
102 #ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
103 _LIBCPP_SAFE_STATIC static atomic<memory_resource*> __res =
104 ATOMIC_VAR_INIT(&res_init.resources.new_delete_res);
105 if (set) {
106 new_res = new_res ? new_res : new_delete_resource();
107 // TODO: Can a weaker ordering be used?
108 return _VSTD::atomic_exchange_explicit(
109 &__res, new_res, memory_order_acq_rel);
110 }
111 else {
112 return _VSTD::atomic_load_explicit(
113 &__res, memory_order_acquire);
114 }
115 #elif !defined(_LIBCPP_HAS_NO_THREADS)
116 _LIBCPP_SAFE_STATIC static memory_resource * res = &res_init.resources.new_delete_res;
117 static mutex res_lock;
118 if (set) {
119 new_res = new_res ? new_res : new_delete_resource();
120 lock_guard<mutex> guard(res_lock);
121 memory_resource * old_res = res;
122 res = new_res;
123 return old_res;
124 } else {
125 lock_guard<mutex> guard(res_lock);
126 return res;
127 }
128 #else
129 _LIBCPP_SAFE_STATIC static memory_resource* res = &res_init.resources.new_delete_res;
130 if (set) {
131 new_res = new_res ? new_res : new_delete_resource();
132 memory_resource * old_res = res;
133 res = new_res;
134 return old_res;
135 } else {
136 return res;
137 }
138 #endif
139 }
140
get_default_resource()141 memory_resource * get_default_resource() _NOEXCEPT
142 {
143 return __default_memory_resource();
144 }
145
set_default_resource(memory_resource * __new_res)146 memory_resource * set_default_resource(memory_resource * __new_res) _NOEXCEPT
147 {
148 return __default_memory_resource(true, __new_res);
149 }
150
151 _LIBCPP_END_NAMESPACE_LFTS_PMR
152