1 //===------------------------ memory_resource.cpp -------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9
10 #include "experimental/memory_resource"
11
12 #ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
13 #include "atomic"
14 #elif !defined(_LIBCPP_HAS_NO_THREADS)
15 #include "mutex"
16 #endif
17
18 _LIBCPP_BEGIN_NAMESPACE_LFTS_PMR
19
20 // memory_resource
21
22 //memory_resource::~memory_resource() {}
23
24 // new_delete_resource()
25
26 class _LIBCPP_TYPE_VIS __new_delete_memory_resource_imp
27 : public memory_resource
28 {
29 public:
30 ~__new_delete_memory_resource_imp() = default;
31
32 protected:
do_allocate(size_t __size,size_t __align)33 virtual void* do_allocate(size_t __size, size_t __align)
34 { return _VSTD::__libcpp_allocate(__size, __align); /* FIXME */}
35
do_deallocate(void * __p,size_t __n,size_t __align)36 virtual void do_deallocate(void* __p, size_t __n, size_t __align) {
37 _VSTD::__libcpp_deallocate(__p, __n, __align); /* FIXME */
38 }
39
do_is_equal(memory_resource const & __other) const40 virtual bool do_is_equal(memory_resource const & __other) const _NOEXCEPT
41 { return &__other == this; }
42 };
43
44 // null_memory_resource()
45
46 class _LIBCPP_TYPE_VIS __null_memory_resource_imp
47 : public memory_resource
48 {
49 public:
50 ~__null_memory_resource_imp() = default;
51
52 protected:
do_allocate(size_t,size_t)53 virtual void* do_allocate(size_t, size_t) {
54 __throw_bad_alloc();
55 }
do_deallocate(void *,size_t,size_t)56 virtual void do_deallocate(void *, size_t, size_t) {}
do_is_equal(memory_resource const & __other) const57 virtual bool do_is_equal(memory_resource const & __other) const _NOEXCEPT
58 { return &__other == this; }
59 };
60
61 namespace {
62
63 union ResourceInitHelper {
64 struct {
65 __new_delete_memory_resource_imp new_delete_res;
66 __null_memory_resource_imp null_res;
67 } resources;
68 char dummy;
ResourceInitHelper()69 _LIBCPP_CONSTEXPR_AFTER_CXX11 ResourceInitHelper() : resources() {}
~ResourceInitHelper()70 ~ResourceInitHelper() {}
71 };
72
73 // Detect if the init_priority attribute is supported.
74 #if (defined(_LIBCPP_COMPILER_GCC) && defined(__APPLE__)) \
75 || defined(_LIBCPP_COMPILER_MSVC)
76 // GCC on Apple doesn't support the init priority attribute,
77 // and MSVC doesn't support any GCC attributes.
78 # define _LIBCPP_INIT_PRIORITY_MAX
79 #else
80 # define _LIBCPP_INIT_PRIORITY_MAX __attribute__((init_priority(101)))
81 #endif
82
83 // When compiled in C++14 this initialization should be a constant expression.
84 // Only in C++11 is "init_priority" needed to ensure initialization order.
85 #if _LIBCPP_STD_VER > 11
86 _LIBCPP_SAFE_STATIC
87 #endif
88 ResourceInitHelper res_init _LIBCPP_INIT_PRIORITY_MAX;
89
90 } // end namespace
91
92
new_delete_resource()93 memory_resource * new_delete_resource() _NOEXCEPT {
94 return &res_init.resources.new_delete_res;
95 }
96
null_memory_resource()97 memory_resource * null_memory_resource() _NOEXCEPT {
98 return &res_init.resources.null_res;
99 }
100
101 // default_memory_resource()
102
103 static memory_resource *
__default_memory_resource(bool set=false,memory_resource * new_res=nullptr)104 __default_memory_resource(bool set = false, memory_resource * new_res = nullptr) _NOEXCEPT
105 {
106 #ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
107 _LIBCPP_SAFE_STATIC static atomic<memory_resource*> __res =
108 ATOMIC_VAR_INIT(&res_init.resources.new_delete_res);
109 if (set) {
110 new_res = new_res ? new_res : new_delete_resource();
111 // TODO: Can a weaker ordering be used?
112 return _VSTD::atomic_exchange_explicit(
113 &__res, new_res, memory_order::memory_order_acq_rel);
114 }
115 else {
116 return _VSTD::atomic_load_explicit(
117 &__res, memory_order::memory_order_acquire);
118 }
119 #elif !defined(_LIBCPP_HAS_NO_THREADS)
120 _LIBCPP_SAFE_STATIC static memory_resource * res = &res_init.resources.new_delete_res;
121 static mutex res_lock;
122 if (set) {
123 new_res = new_res ? new_res : new_delete_resource();
124 lock_guard<mutex> guard(res_lock);
125 memory_resource * old_res = res;
126 res = new_res;
127 return old_res;
128 } else {
129 lock_guard<mutex> guard(res_lock);
130 return res;
131 }
132 #else
133 _LIBCPP_SAFE_STATIC static memory_resource* res = &res_init.resources.new_delete_res;
134 if (set) {
135 new_res = new_res ? new_res : new_delete_resource();
136 memory_resource * old_res = res;
137 res = new_res;
138 return old_res;
139 } else {
140 return res;
141 }
142 #endif
143 }
144
get_default_resource()145 memory_resource * get_default_resource() _NOEXCEPT
146 {
147 return __default_memory_resource();
148 }
149
set_default_resource(memory_resource * __new_res)150 memory_resource * set_default_resource(memory_resource * __new_res) _NOEXCEPT
151 {
152 return __default_memory_resource(true, __new_res);
153 }
154
155 _LIBCPP_END_NAMESPACE_LFTS_PMR
156