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mbed library sources. Supersedes mbed-src.

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platform/SharedPtr.h@189:f392fc9709a3, 2019-02-20 (annotated)

Committer:
AnnaBridge
Date:
Wed Feb 20 22:31:08 2019 +0000
Revision:
189:f392fc9709a3
Parent:
188:bcfe06ba3d64 
mbed library release version 165

Who changed what in which revision?

UserRevisionLine numberNew contents of line
AnnaBridge 188:bcfe06ba3d64 1 /* mbed Microcontroller Library
AnnaBridge 188:bcfe06ba3d64 2 * Copyright (c) 2006-2018 ARM Limited
AnnaBridge 189:f392fc9709a3 3 * SPDX-License-Identifier: Apache-2.0
AnnaBridge 188:bcfe06ba3d64 4 *
AnnaBridge 188:bcfe06ba3d64 5 * Licensed under the Apache License, Version 2.0 (the "License");
AnnaBridge 188:bcfe06ba3d64 6 * you may not use this file except in compliance with the License.
AnnaBridge 188:bcfe06ba3d64 7 * You may obtain a copy of the License at
AnnaBridge 188:bcfe06ba3d64 8 *
AnnaBridge 188:bcfe06ba3d64 9 * http://www.apache.org/licenses/LICENSE-2.0
AnnaBridge 188:bcfe06ba3d64 10 *
AnnaBridge 188:bcfe06ba3d64 11 * Unless required by applicable law or agreed to in writing, software
AnnaBridge 188:bcfe06ba3d64 12 * distributed under the License is distributed on an "AS IS" BASIS,
AnnaBridge 188:bcfe06ba3d64 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
AnnaBridge 188:bcfe06ba3d64 14 * See the License for the specific language governing permissions and
AnnaBridge 188:bcfe06ba3d64 15 * limitations under the License.
AnnaBridge 188:bcfe06ba3d64 16 */
AnnaBridge 188:bcfe06ba3d64 17
AnnaBridge 188:bcfe06ba3d64 18 #ifndef __SHAREDPTR_H__
AnnaBridge 188:bcfe06ba3d64 19 #define __SHAREDPTR_H__
AnnaBridge 188:bcfe06ba3d64 20
AnnaBridge 188:bcfe06ba3d64 21 #include <stdlib.h>
AnnaBridge 188:bcfe06ba3d64 22
AnnaBridge 188:bcfe06ba3d64 23 #include <stdint.h>
AnnaBridge 188:bcfe06ba3d64 24 #include <stddef.h>
AnnaBridge 188:bcfe06ba3d64 25
AnnaBridge 188:bcfe06ba3d64 26 #include "platform/mbed_critical.h"
AnnaBridge 188:bcfe06ba3d64 27
AnnaBridge 189:f392fc9709a3 28 namespace mbed {
AnnaBridge 189:f392fc9709a3 29
AnnaBridge 188:bcfe06ba3d64 30 /** Shared pointer class.
AnnaBridge 188:bcfe06ba3d64 31 *
AnnaBridge 188:bcfe06ba3d64 32 * A shared pointer is a "smart" pointer that retains ownership of an object using
AnnaBridge 189:f392fc9709a3 33 * reference counting across all smart pointers referencing that object.
AnnaBridge 188:bcfe06ba3d64 34 *
AnnaBridge 188:bcfe06ba3d64 35 * @code
AnnaBridge 188:bcfe06ba3d64 36 * #include "platform/SharedPtr.h"
AnnaBridge 188:bcfe06ba3d64 37 *
AnnaBridge 188:bcfe06ba3d64 38 * void test() {
AnnaBridge 188:bcfe06ba3d64 39 * struct MyStruct { int a; };
AnnaBridge 188:bcfe06ba3d64 40 *
AnnaBridge 188:bcfe06ba3d64 41 * // Create shared pointer
AnnaBridge 188:bcfe06ba3d64 42 * SharedPtr<MyStruct> ptr( new MyStruct );
AnnaBridge 188:bcfe06ba3d64 43 *
AnnaBridge 188:bcfe06ba3d64 44 * // Increase reference count
AnnaBridge 188:bcfe06ba3d64 45 * SharedPtr<MyStruct> ptr2( ptr );
AnnaBridge 188:bcfe06ba3d64 46 *
AnnaBridge 188:bcfe06ba3d64 47 * ptr = NULL; // Reference to the struct instance is still held by ptr2
AnnaBridge 188:bcfe06ba3d64 48 *
AnnaBridge 188:bcfe06ba3d64 49 * ptr2 = NULL; // The raw pointer is freed
AnnaBridge 188:bcfe06ba3d64 50 * }
AnnaBridge 188:bcfe06ba3d64 51 * @endcode
AnnaBridge 188:bcfe06ba3d64 52 *
AnnaBridge 188:bcfe06ba3d64 53 *
AnnaBridge 188:bcfe06ba3d64 54 * It is similar to the std::shared_ptr class introduced in C++11;
AnnaBridge 188:bcfe06ba3d64 55 * however, this is not a compatible implementation (no weak pointer, no make_shared, no custom deleters and so on.)
AnnaBridge 188:bcfe06ba3d64 56 *
AnnaBridge 188:bcfe06ba3d64 57 * Usage: SharedPtr<Class> ptr(new Class())
AnnaBridge 188:bcfe06ba3d64 58 *
AnnaBridge 188:bcfe06ba3d64 59 * When ptr is passed around by value, the copy constructor and
AnnaBridge 188:bcfe06ba3d64 60 * destructor manages the reference count of the raw pointer.
AnnaBridge 188:bcfe06ba3d64 61 * If the counter reaches zero, delete is called on the raw pointer.
AnnaBridge 188:bcfe06ba3d64 62 *
AnnaBridge 188:bcfe06ba3d64 63 * To avoid loops, use "weak" references by calling the original
AnnaBridge 188:bcfe06ba3d64 64 * pointer directly through ptr.get().
AnnaBridge 188:bcfe06ba3d64 65 */
AnnaBridge 188:bcfe06ba3d64 66
AnnaBridge 188:bcfe06ba3d64 67 template <class T>
AnnaBridge 188:bcfe06ba3d64 68 class SharedPtr {
AnnaBridge 188:bcfe06ba3d64 69 public:
AnnaBridge 188:bcfe06ba3d64 70 /**
AnnaBridge 188:bcfe06ba3d64 71 * @brief Create empty SharedPtr not pointing to anything.
AnnaBridge 188:bcfe06ba3d64 72 * @details Used for variable declaration.
AnnaBridge 188:bcfe06ba3d64 73 */
AnnaBridge 188:bcfe06ba3d64 74 SharedPtr(): _ptr(NULL), _counter(NULL)
AnnaBridge 188:bcfe06ba3d64 75 {
AnnaBridge 188:bcfe06ba3d64 76 }
AnnaBridge 188:bcfe06ba3d64 77
AnnaBridge 188:bcfe06ba3d64 78 /**
AnnaBridge 188:bcfe06ba3d64 79 * @brief Create new SharedPtr
AnnaBridge 188:bcfe06ba3d64 80 * @param ptr Pointer to take control over
AnnaBridge 188:bcfe06ba3d64 81 */
AnnaBridge 188:bcfe06ba3d64 82 SharedPtr(T *ptr): _ptr(ptr), _counter(NULL)
AnnaBridge 188:bcfe06ba3d64 83 {
AnnaBridge 188:bcfe06ba3d64 84 // Allocate counter on the heap, so it can be shared
AnnaBridge 188:bcfe06ba3d64 85 if (_ptr != NULL) {
AnnaBridge 188:bcfe06ba3d64 86 _counter = new uint32_t;
AnnaBridge 188:bcfe06ba3d64 87 *_counter = 1;
AnnaBridge 188:bcfe06ba3d64 88 }
AnnaBridge 188:bcfe06ba3d64 89 }
AnnaBridge 188:bcfe06ba3d64 90
AnnaBridge 188:bcfe06ba3d64 91 /**
AnnaBridge 188:bcfe06ba3d64 92 * @brief Destructor.
AnnaBridge 188:bcfe06ba3d64 93 * @details Decrement reference counter, and delete object if no longer pointed to.
AnnaBridge 188:bcfe06ba3d64 94 */
AnnaBridge 188:bcfe06ba3d64 95 ~SharedPtr()
AnnaBridge 188:bcfe06ba3d64 96 {
AnnaBridge 188:bcfe06ba3d64 97 decrement_counter();
AnnaBridge 188:bcfe06ba3d64 98 }
AnnaBridge 188:bcfe06ba3d64 99
AnnaBridge 188:bcfe06ba3d64 100 /**
AnnaBridge 188:bcfe06ba3d64 101 * @brief Copy constructor.
AnnaBridge 188:bcfe06ba3d64 102 * @details Create new SharedPtr from other SharedPtr by
AnnaBridge 188:bcfe06ba3d64 103 * copying pointer to original object and pointer to counter.
AnnaBridge 188:bcfe06ba3d64 104 * @param source Object being copied from.
AnnaBridge 188:bcfe06ba3d64 105 */
AnnaBridge 188:bcfe06ba3d64 106 SharedPtr(const SharedPtr &source): _ptr(source._ptr), _counter(source._counter)
AnnaBridge 188:bcfe06ba3d64 107 {
AnnaBridge 188:bcfe06ba3d64 108 // Increment reference counter
AnnaBridge 188:bcfe06ba3d64 109 if (_ptr != NULL) {
AnnaBridge 188:bcfe06ba3d64 110 core_util_atomic_incr_u32(_counter, 1);
AnnaBridge 188:bcfe06ba3d64 111 }
AnnaBridge 188:bcfe06ba3d64 112 }
AnnaBridge 188:bcfe06ba3d64 113
AnnaBridge 188:bcfe06ba3d64 114 /**
AnnaBridge 188:bcfe06ba3d64 115 * @brief Assignment operator.
AnnaBridge 188:bcfe06ba3d64 116 * @details Cleanup previous reference and assign new pointer and counter.
AnnaBridge 188:bcfe06ba3d64 117 * @param source Object being assigned from.
AnnaBridge 188:bcfe06ba3d64 118 * @return Object being assigned.
AnnaBridge 188:bcfe06ba3d64 119 */
AnnaBridge 188:bcfe06ba3d64 120 SharedPtr operator=(const SharedPtr &source)
AnnaBridge 188:bcfe06ba3d64 121 {
AnnaBridge 188:bcfe06ba3d64 122 if (this != &source) {
AnnaBridge 188:bcfe06ba3d64 123 // Clean up by decrementing counter
AnnaBridge 188:bcfe06ba3d64 124 decrement_counter();
AnnaBridge 188:bcfe06ba3d64 125
AnnaBridge 188:bcfe06ba3d64 126 // Assign new values
AnnaBridge 188:bcfe06ba3d64 127 _ptr = source.get();
AnnaBridge 188:bcfe06ba3d64 128 _counter = source.get_counter();
AnnaBridge 188:bcfe06ba3d64 129
AnnaBridge 188:bcfe06ba3d64 130 // Increment new counter
AnnaBridge 188:bcfe06ba3d64 131 if (_ptr != NULL) {
AnnaBridge 188:bcfe06ba3d64 132 core_util_atomic_incr_u32(_counter, 1);
AnnaBridge 188:bcfe06ba3d64 133 }
AnnaBridge 188:bcfe06ba3d64 134 }
AnnaBridge 188:bcfe06ba3d64 135
AnnaBridge 188:bcfe06ba3d64 136 return *this;
AnnaBridge 188:bcfe06ba3d64 137 }
AnnaBridge 188:bcfe06ba3d64 138
AnnaBridge 188:bcfe06ba3d64 139 /**
AnnaBridge 188:bcfe06ba3d64 140 * @brief Replaces the managed pointer with a new unmanaged pointer.
AnnaBridge 188:bcfe06ba3d64 141 * @param[in] ptr the new raw pointer to manage.
AnnaBridge 188:bcfe06ba3d64 142 */
AnnaBridge 188:bcfe06ba3d64 143 void reset(T *ptr)
AnnaBridge 188:bcfe06ba3d64 144 {
AnnaBridge 188:bcfe06ba3d64 145 // Clean up by decrementing counter
AnnaBridge 188:bcfe06ba3d64 146 decrement_counter();
AnnaBridge 188:bcfe06ba3d64 147
AnnaBridge 189:f392fc9709a3 148 _ptr = ptr;
AnnaBridge 188:bcfe06ba3d64 149 if (ptr != NULL) {
AnnaBridge 188:bcfe06ba3d64 150 // Allocate counter on the heap, so it can be shared
AnnaBridge 188:bcfe06ba3d64 151 _counter = new uint32_t;
AnnaBridge 188:bcfe06ba3d64 152 *_counter = 1;
AnnaBridge 189:f392fc9709a3 153 } else {
AnnaBridge 189:f392fc9709a3 154 _counter = NULL;
AnnaBridge 188:bcfe06ba3d64 155 }
AnnaBridge 188:bcfe06ba3d64 156 }
AnnaBridge 188:bcfe06ba3d64 157
AnnaBridge 188:bcfe06ba3d64 158 /**
AnnaBridge 188:bcfe06ba3d64 159 * @brief Replace the managed pointer with a NULL pointer.
AnnaBridge 188:bcfe06ba3d64 160 */
AnnaBridge 188:bcfe06ba3d64 161 void reset()
AnnaBridge 188:bcfe06ba3d64 162 {
AnnaBridge 188:bcfe06ba3d64 163 reset(NULL);
AnnaBridge 188:bcfe06ba3d64 164 }
AnnaBridge 188:bcfe06ba3d64 165
AnnaBridge 188:bcfe06ba3d64 166 /**
AnnaBridge 188:bcfe06ba3d64 167 * @brief Raw pointer accessor.
AnnaBridge 188:bcfe06ba3d64 168 * @details Get raw pointer to object pointed to.
AnnaBridge 188:bcfe06ba3d64 169 * @return Pointer.
AnnaBridge 188:bcfe06ba3d64 170 */
AnnaBridge 188:bcfe06ba3d64 171 T *get() const
AnnaBridge 188:bcfe06ba3d64 172 {
AnnaBridge 188:bcfe06ba3d64 173 return _ptr;
AnnaBridge 188:bcfe06ba3d64 174 }
AnnaBridge 188:bcfe06ba3d64 175
AnnaBridge 188:bcfe06ba3d64 176 /**
AnnaBridge 188:bcfe06ba3d64 177 * @brief Reference count accessor.
AnnaBridge 188:bcfe06ba3d64 178 * @return Reference count.
AnnaBridge 188:bcfe06ba3d64 179 */
AnnaBridge 188:bcfe06ba3d64 180 uint32_t use_count() const
AnnaBridge 188:bcfe06ba3d64 181 {
AnnaBridge 188:bcfe06ba3d64 182 if (_ptr != NULL) {
AnnaBridge 188:bcfe06ba3d64 183 core_util_critical_section_enter();
AnnaBridge 188:bcfe06ba3d64 184 uint32_t current_counter = *_counter;
AnnaBridge 188:bcfe06ba3d64 185 core_util_critical_section_exit();
AnnaBridge 188:bcfe06ba3d64 186 return current_counter;
AnnaBridge 188:bcfe06ba3d64 187 } else {
AnnaBridge 188:bcfe06ba3d64 188 return 0;
AnnaBridge 188:bcfe06ba3d64 189 }
AnnaBridge 188:bcfe06ba3d64 190 }
AnnaBridge 188:bcfe06ba3d64 191
AnnaBridge 188:bcfe06ba3d64 192 /**
AnnaBridge 188:bcfe06ba3d64 193 * @brief Dereference object operator.
AnnaBridge 188:bcfe06ba3d64 194 * @details Override to return the object pointed to.
AnnaBridge 188:bcfe06ba3d64 195 */
AnnaBridge 188:bcfe06ba3d64 196 T &operator*() const
AnnaBridge 188:bcfe06ba3d64 197 {
AnnaBridge 188:bcfe06ba3d64 198 return *_ptr;
AnnaBridge 188:bcfe06ba3d64 199 }
AnnaBridge 188:bcfe06ba3d64 200
AnnaBridge 188:bcfe06ba3d64 201 /**
AnnaBridge 188:bcfe06ba3d64 202 * @brief Dereference object member operator.
AnnaBridge 188:bcfe06ba3d64 203 * @details Override to return return member in object pointed to.
AnnaBridge 188:bcfe06ba3d64 204 */
AnnaBridge 188:bcfe06ba3d64 205 T *operator->() const
AnnaBridge 188:bcfe06ba3d64 206 {
AnnaBridge 188:bcfe06ba3d64 207 return _ptr;
AnnaBridge 188:bcfe06ba3d64 208 }
AnnaBridge 188:bcfe06ba3d64 209
AnnaBridge 188:bcfe06ba3d64 210 /**
AnnaBridge 188:bcfe06ba3d64 211 * @brief Boolean conversion operator.
AnnaBridge 188:bcfe06ba3d64 212 * @return Whether or not the pointer is NULL.
AnnaBridge 188:bcfe06ba3d64 213 */
AnnaBridge 188:bcfe06ba3d64 214 operator bool() const
AnnaBridge 188:bcfe06ba3d64 215 {
AnnaBridge 188:bcfe06ba3d64 216 return (_ptr != NULL);
AnnaBridge 188:bcfe06ba3d64 217 }
AnnaBridge 188:bcfe06ba3d64 218
AnnaBridge 188:bcfe06ba3d64 219 private:
AnnaBridge 188:bcfe06ba3d64 220 /**
AnnaBridge 188:bcfe06ba3d64 221 * @brief Get pointer to reference counter.
AnnaBridge 188:bcfe06ba3d64 222 * @return Pointer to reference counter.
AnnaBridge 188:bcfe06ba3d64 223 */
AnnaBridge 188:bcfe06ba3d64 224 uint32_t *get_counter() const
AnnaBridge 188:bcfe06ba3d64 225 {
AnnaBridge 188:bcfe06ba3d64 226 return _counter;
AnnaBridge 188:bcfe06ba3d64 227 }
AnnaBridge 188:bcfe06ba3d64 228
AnnaBridge 188:bcfe06ba3d64 229 /**
AnnaBridge 188:bcfe06ba3d64 230 * @brief Decrement reference counter.
AnnaBridge 188:bcfe06ba3d64 231 * @details If count reaches zero, free counter and delete object pointed to.
AnnaBridge 189:f392fc9709a3 232 * Does not modify our own pointers - assumption is they will be overwritten
AnnaBridge 189:f392fc9709a3 233 * or destroyed immediately afterwards.
AnnaBridge 188:bcfe06ba3d64 234 */
AnnaBridge 188:bcfe06ba3d64 235 void decrement_counter()
AnnaBridge 188:bcfe06ba3d64 236 {
AnnaBridge 188:bcfe06ba3d64 237 if (_ptr != NULL) {
AnnaBridge 188:bcfe06ba3d64 238 uint32_t new_value = core_util_atomic_decr_u32(_counter, 1);
AnnaBridge 188:bcfe06ba3d64 239 if (new_value == 0) {
AnnaBridge 188:bcfe06ba3d64 240 delete _counter;
AnnaBridge 188:bcfe06ba3d64 241 delete _ptr;
AnnaBridge 188:bcfe06ba3d64 242 }
AnnaBridge 188:bcfe06ba3d64 243 }
AnnaBridge 188:bcfe06ba3d64 244 }
AnnaBridge 188:bcfe06ba3d64 245
AnnaBridge 188:bcfe06ba3d64 246 private:
AnnaBridge 188:bcfe06ba3d64 247 // Pointer to shared object
AnnaBridge 188:bcfe06ba3d64 248 T *_ptr;
AnnaBridge 188:bcfe06ba3d64 249
AnnaBridge 188:bcfe06ba3d64 250 // Pointer to shared reference counter
AnnaBridge 188:bcfe06ba3d64 251 uint32_t *_counter;
AnnaBridge 188:bcfe06ba3d64 252 };
AnnaBridge 188:bcfe06ba3d64 253
AnnaBridge 188:bcfe06ba3d64 254 /** Non-member relational operators.
AnnaBridge 188:bcfe06ba3d64 255 */
AnnaBridge 188:bcfe06ba3d64 256 template <class T, class U>
AnnaBridge 188:bcfe06ba3d64 257 bool operator== (const SharedPtr<T> &lhs, const SharedPtr<U> &rhs)
AnnaBridge 188:bcfe06ba3d64 258 {
AnnaBridge 188:bcfe06ba3d64 259 return (lhs.get() == rhs.get());
AnnaBridge 188:bcfe06ba3d64 260 }
AnnaBridge 188:bcfe06ba3d64 261
AnnaBridge 188:bcfe06ba3d64 262 template <class T, typename U>
AnnaBridge 188:bcfe06ba3d64 263 bool operator== (const SharedPtr<T> &lhs, U rhs)
AnnaBridge 188:bcfe06ba3d64 264 {
AnnaBridge 188:bcfe06ba3d64 265 return (lhs.get() == (T *) rhs);
AnnaBridge 188:bcfe06ba3d64 266 }
AnnaBridge 188:bcfe06ba3d64 267
AnnaBridge 188:bcfe06ba3d64 268 template <class T, typename U>
AnnaBridge 188:bcfe06ba3d64 269 bool operator== (U lhs, const SharedPtr<T> &rhs)
AnnaBridge 188:bcfe06ba3d64 270 {
AnnaBridge 188:bcfe06ba3d64 271 return ((T *) lhs == rhs.get());
AnnaBridge 188:bcfe06ba3d64 272 }
AnnaBridge 188:bcfe06ba3d64 273
AnnaBridge 188:bcfe06ba3d64 274 /** Non-member relational operators.
AnnaBridge 188:bcfe06ba3d64 275 */
AnnaBridge 188:bcfe06ba3d64 276 template <class T, class U>
AnnaBridge 188:bcfe06ba3d64 277 bool operator!= (const SharedPtr<T> &lhs, const SharedPtr<U> &rhs)
AnnaBridge 188:bcfe06ba3d64 278 {
AnnaBridge 188:bcfe06ba3d64 279 return (lhs.get() != rhs.get());
AnnaBridge 188:bcfe06ba3d64 280 }
AnnaBridge 188:bcfe06ba3d64 281
AnnaBridge 188:bcfe06ba3d64 282 template <class T, typename U>
AnnaBridge 188:bcfe06ba3d64 283 bool operator!= (const SharedPtr<T> &lhs, U rhs)
AnnaBridge 188:bcfe06ba3d64 284 {
AnnaBridge 188:bcfe06ba3d64 285 return (lhs.get() != (T *) rhs);
AnnaBridge 188:bcfe06ba3d64 286 }
AnnaBridge 188:bcfe06ba3d64 287
AnnaBridge 188:bcfe06ba3d64 288 template <class T, typename U>
AnnaBridge 188:bcfe06ba3d64 289 bool operator!= (U lhs, const SharedPtr<T> &rhs)
AnnaBridge 188:bcfe06ba3d64 290 {
AnnaBridge 188:bcfe06ba3d64 291 return ((T *) lhs != rhs.get());
AnnaBridge 188:bcfe06ba3d64 292 }
AnnaBridge 188:bcfe06ba3d64 293
AnnaBridge 189:f392fc9709a3 294 } /* namespace mbed */
AnnaBridge 189:f392fc9709a3 295
AnnaBridge 189:f392fc9709a3 296 #ifndef MBED_NO_GLOBAL_USING_DIRECTIVE
AnnaBridge 189:f392fc9709a3 297 using mbed::SharedPtr;
AnnaBridge 189:f392fc9709a3 298 #endif
AnnaBridge 189:f392fc9709a3 299
AnnaBridge 188:bcfe06ba3d64 300 #endif // __SHAREDPTR_H__