mbed official / mbed-dev

mbed library sources. Supersedes mbed-src.

Dependents:   Nucleo_Hello_Encoder BLE_iBeaconScan AM1805_DEMO DISCO-F429ZI_ExportTemplate1 ... more

platform/SharedPtr.h@188:bcfe06ba3d64, 2018-11-08 (annotated)

Committer:
AnnaBridge
Date:
Thu Nov 08 11:46:34 2018 +0000
Revision:
188:bcfe06ba3d64
Child:
189:f392fc9709a3
mbed-dev library. Release version 164

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