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platform/SharedPtr.h@0:38ceb79fef03, 2018-11-28 (annotated)
- Committer:
- kevman
- Date:
- Wed Nov 28 15:10:15 2018 +0000
- Revision:
- 0:38ceb79fef03
RTC modified
Who changed what in which revision?
User | Revision | Line number | New contents of line |
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kevman | 0:38ceb79fef03 | 1 | /* mbed Microcontroller Library |
kevman | 0:38ceb79fef03 | 2 | * Copyright (c) 2006-2018 ARM Limited |
kevman | 0:38ceb79fef03 | 3 | * |
kevman | 0:38ceb79fef03 | 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
kevman | 0:38ceb79fef03 | 5 | * you may not use this file except in compliance with the License. |
kevman | 0:38ceb79fef03 | 6 | * You may obtain a copy of the License at |
kevman | 0:38ceb79fef03 | 7 | * |
kevman | 0:38ceb79fef03 | 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
kevman | 0:38ceb79fef03 | 9 | * |
kevman | 0:38ceb79fef03 | 10 | * Unless required by applicable law or agreed to in writing, software |
kevman | 0:38ceb79fef03 | 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
kevman | 0:38ceb79fef03 | 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
kevman | 0:38ceb79fef03 | 13 | * See the License for the specific language governing permissions and |
kevman | 0:38ceb79fef03 | 14 | * limitations under the License. |
kevman | 0:38ceb79fef03 | 15 | */ |
kevman | 0:38ceb79fef03 | 16 | |
kevman | 0:38ceb79fef03 | 17 | #ifndef __SHAREDPTR_H__ |
kevman | 0:38ceb79fef03 | 18 | #define __SHAREDPTR_H__ |
kevman | 0:38ceb79fef03 | 19 | |
kevman | 0:38ceb79fef03 | 20 | #include <stdlib.h> |
kevman | 0:38ceb79fef03 | 21 | |
kevman | 0:38ceb79fef03 | 22 | #include <stdint.h> |
kevman | 0:38ceb79fef03 | 23 | #include <stddef.h> |
kevman | 0:38ceb79fef03 | 24 | |
kevman | 0:38ceb79fef03 | 25 | #include "platform/mbed_critical.h" |
kevman | 0:38ceb79fef03 | 26 | |
kevman | 0:38ceb79fef03 | 27 | /** Shared pointer class. |
kevman | 0:38ceb79fef03 | 28 | * |
kevman | 0:38ceb79fef03 | 29 | * A shared pointer is a "smart" pointer that retains ownership of an object using |
kevman | 0:38ceb79fef03 | 30 | * reference counting accross all smart pointers referencing that object. |
kevman | 0:38ceb79fef03 | 31 | * |
kevman | 0:38ceb79fef03 | 32 | * @code |
kevman | 0:38ceb79fef03 | 33 | * #include "platform/SharedPtr.h" |
kevman | 0:38ceb79fef03 | 34 | * |
kevman | 0:38ceb79fef03 | 35 | * void test() { |
kevman | 0:38ceb79fef03 | 36 | * struct MyStruct { int a; }; |
kevman | 0:38ceb79fef03 | 37 | * |
kevman | 0:38ceb79fef03 | 38 | * // Create shared pointer |
kevman | 0:38ceb79fef03 | 39 | * SharedPtr<MyStruct> ptr( new MyStruct ); |
kevman | 0:38ceb79fef03 | 40 | * |
kevman | 0:38ceb79fef03 | 41 | * // Increase reference count |
kevman | 0:38ceb79fef03 | 42 | * SharedPtr<MyStruct> ptr2( ptr ); |
kevman | 0:38ceb79fef03 | 43 | * |
kevman | 0:38ceb79fef03 | 44 | * ptr = NULL; // Reference to the struct instance is still held by ptr2 |
kevman | 0:38ceb79fef03 | 45 | * |
kevman | 0:38ceb79fef03 | 46 | * ptr2 = NULL; // The raw pointer is freed |
kevman | 0:38ceb79fef03 | 47 | * } |
kevman | 0:38ceb79fef03 | 48 | * @endcode |
kevman | 0:38ceb79fef03 | 49 | * |
kevman | 0:38ceb79fef03 | 50 | * |
kevman | 0:38ceb79fef03 | 51 | * It is similar to the std::shared_ptr class introduced in C++11; |
kevman | 0:38ceb79fef03 | 52 | * however, this is not a compatible implementation (no weak pointer, no make_shared, no custom deleters and so on.) |
kevman | 0:38ceb79fef03 | 53 | * |
kevman | 0:38ceb79fef03 | 54 | * Usage: SharedPtr<Class> ptr(new Class()) |
kevman | 0:38ceb79fef03 | 55 | * |
kevman | 0:38ceb79fef03 | 56 | * When ptr is passed around by value, the copy constructor and |
kevman | 0:38ceb79fef03 | 57 | * destructor manages the reference count of the raw pointer. |
kevman | 0:38ceb79fef03 | 58 | * If the counter reaches zero, delete is called on the raw pointer. |
kevman | 0:38ceb79fef03 | 59 | * |
kevman | 0:38ceb79fef03 | 60 | * To avoid loops, use "weak" references by calling the original |
kevman | 0:38ceb79fef03 | 61 | * pointer directly through ptr.get(). |
kevman | 0:38ceb79fef03 | 62 | */ |
kevman | 0:38ceb79fef03 | 63 | |
kevman | 0:38ceb79fef03 | 64 | template <class T> |
kevman | 0:38ceb79fef03 | 65 | class SharedPtr { |
kevman | 0:38ceb79fef03 | 66 | public: |
kevman | 0:38ceb79fef03 | 67 | /** |
kevman | 0:38ceb79fef03 | 68 | * @brief Create empty SharedPtr not pointing to anything. |
kevman | 0:38ceb79fef03 | 69 | * @details Used for variable declaration. |
kevman | 0:38ceb79fef03 | 70 | */ |
kevman | 0:38ceb79fef03 | 71 | SharedPtr(): _ptr(NULL), _counter(NULL) |
kevman | 0:38ceb79fef03 | 72 | { |
kevman | 0:38ceb79fef03 | 73 | } |
kevman | 0:38ceb79fef03 | 74 | |
kevman | 0:38ceb79fef03 | 75 | /** |
kevman | 0:38ceb79fef03 | 76 | * @brief Create new SharedPtr |
kevman | 0:38ceb79fef03 | 77 | * @param ptr Pointer to take control over |
kevman | 0:38ceb79fef03 | 78 | */ |
kevman | 0:38ceb79fef03 | 79 | SharedPtr(T *ptr): _ptr(ptr), _counter(NULL) |
kevman | 0:38ceb79fef03 | 80 | { |
kevman | 0:38ceb79fef03 | 81 | // Allocate counter on the heap, so it can be shared |
kevman | 0:38ceb79fef03 | 82 | if (_ptr != NULL) { |
kevman | 0:38ceb79fef03 | 83 | _counter = new uint32_t; |
kevman | 0:38ceb79fef03 | 84 | *_counter = 1; |
kevman | 0:38ceb79fef03 | 85 | } |
kevman | 0:38ceb79fef03 | 86 | } |
kevman | 0:38ceb79fef03 | 87 | |
kevman | 0:38ceb79fef03 | 88 | /** |
kevman | 0:38ceb79fef03 | 89 | * @brief Destructor. |
kevman | 0:38ceb79fef03 | 90 | * @details Decrement reference counter, and delete object if no longer pointed to. |
kevman | 0:38ceb79fef03 | 91 | */ |
kevman | 0:38ceb79fef03 | 92 | ~SharedPtr() |
kevman | 0:38ceb79fef03 | 93 | { |
kevman | 0:38ceb79fef03 | 94 | decrement_counter(); |
kevman | 0:38ceb79fef03 | 95 | } |
kevman | 0:38ceb79fef03 | 96 | |
kevman | 0:38ceb79fef03 | 97 | /** |
kevman | 0:38ceb79fef03 | 98 | * @brief Copy constructor. |
kevman | 0:38ceb79fef03 | 99 | * @details Create new SharedPtr from other SharedPtr by |
kevman | 0:38ceb79fef03 | 100 | * copying pointer to original object and pointer to counter. |
kevman | 0:38ceb79fef03 | 101 | * @param source Object being copied from. |
kevman | 0:38ceb79fef03 | 102 | */ |
kevman | 0:38ceb79fef03 | 103 | SharedPtr(const SharedPtr &source): _ptr(source._ptr), _counter(source._counter) |
kevman | 0:38ceb79fef03 | 104 | { |
kevman | 0:38ceb79fef03 | 105 | // Increment reference counter |
kevman | 0:38ceb79fef03 | 106 | if (_ptr != NULL) { |
kevman | 0:38ceb79fef03 | 107 | core_util_atomic_incr_u32(_counter, 1); |
kevman | 0:38ceb79fef03 | 108 | } |
kevman | 0:38ceb79fef03 | 109 | } |
kevman | 0:38ceb79fef03 | 110 | |
kevman | 0:38ceb79fef03 | 111 | /** |
kevman | 0:38ceb79fef03 | 112 | * @brief Assignment operator. |
kevman | 0:38ceb79fef03 | 113 | * @details Cleanup previous reference and assign new pointer and counter. |
kevman | 0:38ceb79fef03 | 114 | * @param source Object being assigned from. |
kevman | 0:38ceb79fef03 | 115 | * @return Object being assigned. |
kevman | 0:38ceb79fef03 | 116 | */ |
kevman | 0:38ceb79fef03 | 117 | SharedPtr operator=(const SharedPtr &source) |
kevman | 0:38ceb79fef03 | 118 | { |
kevman | 0:38ceb79fef03 | 119 | if (this != &source) { |
kevman | 0:38ceb79fef03 | 120 | // Clean up by decrementing counter |
kevman | 0:38ceb79fef03 | 121 | decrement_counter(); |
kevman | 0:38ceb79fef03 | 122 | |
kevman | 0:38ceb79fef03 | 123 | // Assign new values |
kevman | 0:38ceb79fef03 | 124 | _ptr = source.get(); |
kevman | 0:38ceb79fef03 | 125 | _counter = source.get_counter(); |
kevman | 0:38ceb79fef03 | 126 | |
kevman | 0:38ceb79fef03 | 127 | // Increment new counter |
kevman | 0:38ceb79fef03 | 128 | if (_ptr != NULL) { |
kevman | 0:38ceb79fef03 | 129 | core_util_atomic_incr_u32(_counter, 1); |
kevman | 0:38ceb79fef03 | 130 | } |
kevman | 0:38ceb79fef03 | 131 | } |
kevman | 0:38ceb79fef03 | 132 | |
kevman | 0:38ceb79fef03 | 133 | return *this; |
kevman | 0:38ceb79fef03 | 134 | } |
kevman | 0:38ceb79fef03 | 135 | |
kevman | 0:38ceb79fef03 | 136 | /** |
kevman | 0:38ceb79fef03 | 137 | * @brief Replaces the managed pointer with a new unmanaged pointer. |
kevman | 0:38ceb79fef03 | 138 | * @param[in] ptr the new raw pointer to manage. |
kevman | 0:38ceb79fef03 | 139 | */ |
kevman | 0:38ceb79fef03 | 140 | void reset(T *ptr) |
kevman | 0:38ceb79fef03 | 141 | { |
kevman | 0:38ceb79fef03 | 142 | // Clean up by decrementing counter |
kevman | 0:38ceb79fef03 | 143 | decrement_counter(); |
kevman | 0:38ceb79fef03 | 144 | |
kevman | 0:38ceb79fef03 | 145 | if (ptr != NULL) { |
kevman | 0:38ceb79fef03 | 146 | // Allocate counter on the heap, so it can be shared |
kevman | 0:38ceb79fef03 | 147 | _counter = new uint32_t; |
kevman | 0:38ceb79fef03 | 148 | *_counter = 1; |
kevman | 0:38ceb79fef03 | 149 | } |
kevman | 0:38ceb79fef03 | 150 | } |
kevman | 0:38ceb79fef03 | 151 | |
kevman | 0:38ceb79fef03 | 152 | /** |
kevman | 0:38ceb79fef03 | 153 | * @brief Replace the managed pointer with a NULL pointer. |
kevman | 0:38ceb79fef03 | 154 | */ |
kevman | 0:38ceb79fef03 | 155 | void reset() |
kevman | 0:38ceb79fef03 | 156 | { |
kevman | 0:38ceb79fef03 | 157 | reset(NULL); |
kevman | 0:38ceb79fef03 | 158 | } |
kevman | 0:38ceb79fef03 | 159 | |
kevman | 0:38ceb79fef03 | 160 | /** |
kevman | 0:38ceb79fef03 | 161 | * @brief Raw pointer accessor. |
kevman | 0:38ceb79fef03 | 162 | * @details Get raw pointer to object pointed to. |
kevman | 0:38ceb79fef03 | 163 | * @return Pointer. |
kevman | 0:38ceb79fef03 | 164 | */ |
kevman | 0:38ceb79fef03 | 165 | T *get() const |
kevman | 0:38ceb79fef03 | 166 | { |
kevman | 0:38ceb79fef03 | 167 | return _ptr; |
kevman | 0:38ceb79fef03 | 168 | } |
kevman | 0:38ceb79fef03 | 169 | |
kevman | 0:38ceb79fef03 | 170 | /** |
kevman | 0:38ceb79fef03 | 171 | * @brief Reference count accessor. |
kevman | 0:38ceb79fef03 | 172 | * @return Reference count. |
kevman | 0:38ceb79fef03 | 173 | */ |
kevman | 0:38ceb79fef03 | 174 | uint32_t use_count() const |
kevman | 0:38ceb79fef03 | 175 | { |
kevman | 0:38ceb79fef03 | 176 | if (_ptr != NULL) { |
kevman | 0:38ceb79fef03 | 177 | core_util_critical_section_enter(); |
kevman | 0:38ceb79fef03 | 178 | uint32_t current_counter = *_counter; |
kevman | 0:38ceb79fef03 | 179 | core_util_critical_section_exit(); |
kevman | 0:38ceb79fef03 | 180 | return current_counter; |
kevman | 0:38ceb79fef03 | 181 | } else { |
kevman | 0:38ceb79fef03 | 182 | return 0; |
kevman | 0:38ceb79fef03 | 183 | } |
kevman | 0:38ceb79fef03 | 184 | } |
kevman | 0:38ceb79fef03 | 185 | |
kevman | 0:38ceb79fef03 | 186 | /** |
kevman | 0:38ceb79fef03 | 187 | * @brief Dereference object operator. |
kevman | 0:38ceb79fef03 | 188 | * @details Override to return the object pointed to. |
kevman | 0:38ceb79fef03 | 189 | */ |
kevman | 0:38ceb79fef03 | 190 | T &operator*() const |
kevman | 0:38ceb79fef03 | 191 | { |
kevman | 0:38ceb79fef03 | 192 | return *_ptr; |
kevman | 0:38ceb79fef03 | 193 | } |
kevman | 0:38ceb79fef03 | 194 | |
kevman | 0:38ceb79fef03 | 195 | /** |
kevman | 0:38ceb79fef03 | 196 | * @brief Dereference object member operator. |
kevman | 0:38ceb79fef03 | 197 | * @details Override to return return member in object pointed to. |
kevman | 0:38ceb79fef03 | 198 | */ |
kevman | 0:38ceb79fef03 | 199 | T *operator->() const |
kevman | 0:38ceb79fef03 | 200 | { |
kevman | 0:38ceb79fef03 | 201 | return _ptr; |
kevman | 0:38ceb79fef03 | 202 | } |
kevman | 0:38ceb79fef03 | 203 | |
kevman | 0:38ceb79fef03 | 204 | /** |
kevman | 0:38ceb79fef03 | 205 | * @brief Boolean conversion operator. |
kevman | 0:38ceb79fef03 | 206 | * @return Whether or not the pointer is NULL. |
kevman | 0:38ceb79fef03 | 207 | */ |
kevman | 0:38ceb79fef03 | 208 | operator bool() const |
kevman | 0:38ceb79fef03 | 209 | { |
kevman | 0:38ceb79fef03 | 210 | return (_ptr != NULL); |
kevman | 0:38ceb79fef03 | 211 | } |
kevman | 0:38ceb79fef03 | 212 | |
kevman | 0:38ceb79fef03 | 213 | private: |
kevman | 0:38ceb79fef03 | 214 | /** |
kevman | 0:38ceb79fef03 | 215 | * @brief Get pointer to reference counter. |
kevman | 0:38ceb79fef03 | 216 | * @return Pointer to reference counter. |
kevman | 0:38ceb79fef03 | 217 | */ |
kevman | 0:38ceb79fef03 | 218 | uint32_t *get_counter() const |
kevman | 0:38ceb79fef03 | 219 | { |
kevman | 0:38ceb79fef03 | 220 | return _counter; |
kevman | 0:38ceb79fef03 | 221 | } |
kevman | 0:38ceb79fef03 | 222 | |
kevman | 0:38ceb79fef03 | 223 | /** |
kevman | 0:38ceb79fef03 | 224 | * @brief Decrement reference counter. |
kevman | 0:38ceb79fef03 | 225 | * @details If count reaches zero, free counter and delete object pointed to. |
kevman | 0:38ceb79fef03 | 226 | */ |
kevman | 0:38ceb79fef03 | 227 | void decrement_counter() |
kevman | 0:38ceb79fef03 | 228 | { |
kevman | 0:38ceb79fef03 | 229 | if (_ptr != NULL) { |
kevman | 0:38ceb79fef03 | 230 | uint32_t new_value = core_util_atomic_decr_u32(_counter, 1); |
kevman | 0:38ceb79fef03 | 231 | if (new_value == 0) { |
kevman | 0:38ceb79fef03 | 232 | delete _counter; |
kevman | 0:38ceb79fef03 | 233 | _counter = NULL; |
kevman | 0:38ceb79fef03 | 234 | delete _ptr; |
kevman | 0:38ceb79fef03 | 235 | _ptr = NULL; |
kevman | 0:38ceb79fef03 | 236 | } |
kevman | 0:38ceb79fef03 | 237 | } |
kevman | 0:38ceb79fef03 | 238 | } |
kevman | 0:38ceb79fef03 | 239 | |
kevman | 0:38ceb79fef03 | 240 | private: |
kevman | 0:38ceb79fef03 | 241 | // Pointer to shared object |
kevman | 0:38ceb79fef03 | 242 | T *_ptr; |
kevman | 0:38ceb79fef03 | 243 | |
kevman | 0:38ceb79fef03 | 244 | // Pointer to shared reference counter |
kevman | 0:38ceb79fef03 | 245 | uint32_t *_counter; |
kevman | 0:38ceb79fef03 | 246 | }; |
kevman | 0:38ceb79fef03 | 247 | |
kevman | 0:38ceb79fef03 | 248 | /** Non-member relational operators. |
kevman | 0:38ceb79fef03 | 249 | */ |
kevman | 0:38ceb79fef03 | 250 | template <class T, class U> |
kevman | 0:38ceb79fef03 | 251 | bool operator== (const SharedPtr<T> &lhs, const SharedPtr<U> &rhs) |
kevman | 0:38ceb79fef03 | 252 | { |
kevman | 0:38ceb79fef03 | 253 | return (lhs.get() == rhs.get()); |
kevman | 0:38ceb79fef03 | 254 | } |
kevman | 0:38ceb79fef03 | 255 | |
kevman | 0:38ceb79fef03 | 256 | template <class T, typename U> |
kevman | 0:38ceb79fef03 | 257 | bool operator== (const SharedPtr<T> &lhs, U rhs) |
kevman | 0:38ceb79fef03 | 258 | { |
kevman | 0:38ceb79fef03 | 259 | return (lhs.get() == (T *) rhs); |
kevman | 0:38ceb79fef03 | 260 | } |
kevman | 0:38ceb79fef03 | 261 | |
kevman | 0:38ceb79fef03 | 262 | template <class T, typename U> |
kevman | 0:38ceb79fef03 | 263 | bool operator== (U lhs, const SharedPtr<T> &rhs) |
kevman | 0:38ceb79fef03 | 264 | { |
kevman | 0:38ceb79fef03 | 265 | return ((T *) lhs == rhs.get()); |
kevman | 0:38ceb79fef03 | 266 | } |
kevman | 0:38ceb79fef03 | 267 | |
kevman | 0:38ceb79fef03 | 268 | /** Non-member relational operators. |
kevman | 0:38ceb79fef03 | 269 | */ |
kevman | 0:38ceb79fef03 | 270 | template <class T, class U> |
kevman | 0:38ceb79fef03 | 271 | bool operator!= (const SharedPtr<T> &lhs, const SharedPtr<U> &rhs) |
kevman | 0:38ceb79fef03 | 272 | { |
kevman | 0:38ceb79fef03 | 273 | return (lhs.get() != rhs.get()); |
kevman | 0:38ceb79fef03 | 274 | } |
kevman | 0:38ceb79fef03 | 275 | |
kevman | 0:38ceb79fef03 | 276 | template <class T, typename U> |
kevman | 0:38ceb79fef03 | 277 | bool operator!= (const SharedPtr<T> &lhs, U rhs) |
kevman | 0:38ceb79fef03 | 278 | { |
kevman | 0:38ceb79fef03 | 279 | return (lhs.get() != (T *) rhs); |
kevman | 0:38ceb79fef03 | 280 | } |
kevman | 0:38ceb79fef03 | 281 | |
kevman | 0:38ceb79fef03 | 282 | template <class T, typename U> |
kevman | 0:38ceb79fef03 | 283 | bool operator!= (U lhs, const SharedPtr<T> &rhs) |
kevman | 0:38ceb79fef03 | 284 | { |
kevman | 0:38ceb79fef03 | 285 | return ((T *) lhs != rhs.get()); |
kevman | 0:38ceb79fef03 | 286 | } |
kevman | 0:38ceb79fef03 | 287 | |
kevman | 0:38ceb79fef03 | 288 | #endif // __SHAREDPTR_H__ |