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rtos/ConditionVariable.h@2:7aab896b1a3b, 2019-03-13 (annotated)
- Committer:
- kevman
- Date:
- Wed Mar 13 11:03:24 2019 +0000
- Revision:
- 2:7aab896b1a3b
- Parent:
- 0:38ceb79fef03
2019-03-13
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) 2017-2018 ARM Limited |
kevman | 0:38ceb79fef03 | 3 | * |
kevman | 0:38ceb79fef03 | 4 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
kevman | 0:38ceb79fef03 | 5 | * of this software and associated documentation files (the "Software"), to deal |
kevman | 0:38ceb79fef03 | 6 | * in the Software without restriction, including without limitation the rights |
kevman | 0:38ceb79fef03 | 7 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
kevman | 0:38ceb79fef03 | 8 | * copies of the Software, and to permit persons to whom the Software is |
kevman | 0:38ceb79fef03 | 9 | * furnished to do so, subject to the following conditions: |
kevman | 0:38ceb79fef03 | 10 | * |
kevman | 0:38ceb79fef03 | 11 | * The above copyright notice and this permission notice shall be included in |
kevman | 0:38ceb79fef03 | 12 | * all copies or substantial portions of the Software. |
kevman | 0:38ceb79fef03 | 13 | * |
kevman | 0:38ceb79fef03 | 14 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
kevman | 0:38ceb79fef03 | 15 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
kevman | 0:38ceb79fef03 | 16 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
kevman | 0:38ceb79fef03 | 17 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
kevman | 0:38ceb79fef03 | 18 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
kevman | 0:38ceb79fef03 | 19 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
kevman | 0:38ceb79fef03 | 20 | * SOFTWARE. |
kevman | 0:38ceb79fef03 | 21 | */ |
kevman | 0:38ceb79fef03 | 22 | #ifndef CONDITIONVARIABLE_H |
kevman | 0:38ceb79fef03 | 23 | #define CONDITIONVARIABLE_H |
kevman | 0:38ceb79fef03 | 24 | |
kevman | 0:38ceb79fef03 | 25 | #include <stdint.h> |
kevman | 0:38ceb79fef03 | 26 | #include "cmsis_os.h" |
kevman | 0:38ceb79fef03 | 27 | #include "rtos/Mutex.h" |
kevman | 0:38ceb79fef03 | 28 | #include "rtos/Semaphore.h" |
kevman | 0:38ceb79fef03 | 29 | |
kevman | 0:38ceb79fef03 | 30 | #include "platform/NonCopyable.h" |
kevman | 0:38ceb79fef03 | 31 | |
kevman | 0:38ceb79fef03 | 32 | namespace rtos { |
kevman | 0:38ceb79fef03 | 33 | /** \addtogroup rtos */ |
kevman | 0:38ceb79fef03 | 34 | /** @{*/ |
kevman | 0:38ceb79fef03 | 35 | |
kevman | 0:38ceb79fef03 | 36 | struct Waiter; |
kevman | 0:38ceb79fef03 | 37 | |
kevman | 0:38ceb79fef03 | 38 | /** The ConditionVariable class is a synchronization primitive that allows |
kevman | 0:38ceb79fef03 | 39 | * threads to wait until a particular condition occurs. |
kevman | 0:38ceb79fef03 | 40 | * |
kevman | 0:38ceb79fef03 | 41 | * Use the condition variable in conjunction with a mutex to safely wait for |
kevman | 0:38ceb79fef03 | 42 | * or notify waiters of condition changes to a resource accessible by multiple |
kevman | 0:38ceb79fef03 | 43 | * threads. |
kevman | 0:38ceb79fef03 | 44 | * |
kevman | 0:38ceb79fef03 | 45 | * The thread that intends to wait on a ConditionVariable must: |
kevman | 0:38ceb79fef03 | 46 | * - Acquire a lock on a mutex. |
kevman | 0:38ceb79fef03 | 47 | * - Execute `wait`, `wait_for` or `wait_until`. While the thread is waiting, |
kevman | 0:38ceb79fef03 | 48 | * the mutex is unlocked. |
kevman | 0:38ceb79fef03 | 49 | * - When the condition variable has been notified, or in the case of `wait_for` |
kevman | 0:38ceb79fef03 | 50 | * and `wait_until` the timeout expires, the thread is awakened. |
kevman | 0:38ceb79fef03 | 51 | * |
kevman | 0:38ceb79fef03 | 52 | * The thread that intends to notify a ConditionVariable must: |
kevman | 0:38ceb79fef03 | 53 | * - Acquire a lock on the mutex used to construct the condition variable. |
kevman | 0:38ceb79fef03 | 54 | * - Execute `notify_one` or `notify_all` on the condition variable. |
kevman | 0:38ceb79fef03 | 55 | * |
kevman | 0:38ceb79fef03 | 56 | * All threads waiting on the condition variable wake when |
kevman | 0:38ceb79fef03 | 57 | * `ConditionVariable::notify_all` is called. |
kevman | 0:38ceb79fef03 | 58 | * At least one thread waiting on the condition variable wakes |
kevman | 0:38ceb79fef03 | 59 | * when `ConditionVariable::notify_one` is called. |
kevman | 0:38ceb79fef03 | 60 | * |
kevman | 0:38ceb79fef03 | 61 | * While a thread is waiting for notification of a |
kevman | 0:38ceb79fef03 | 62 | * ConditionVariable, it releases the lock held on the mutex. |
kevman | 0:38ceb79fef03 | 63 | * The ConditionVariable reacquires the mutex lock before exiting the wait |
kevman | 0:38ceb79fef03 | 64 | * function. |
kevman | 0:38ceb79fef03 | 65 | * |
kevman | 0:38ceb79fef03 | 66 | * #### Unspecified behavior |
kevman | 0:38ceb79fef03 | 67 | * - The thread that is unblocked on `ConditionVariable::notify_one` is |
kevman | 0:38ceb79fef03 | 68 | * unspecified if there are multiple waiters. |
kevman | 0:38ceb79fef03 | 69 | * - When `ConditionVariable::notify_one` or `ConditionVariable::notify_all` is |
kevman | 0:38ceb79fef03 | 70 | * called and there are one or more waiters, and one or more threads |
kevman | 0:38ceb79fef03 | 71 | * attempting to acquire the condition variable's mutex, the order in which the mutex is |
kevman | 0:38ceb79fef03 | 72 | * acquired is unspecified. |
kevman | 0:38ceb79fef03 | 73 | * - Spurious notifications (not triggered by the application) can occur. |
kevman | 0:38ceb79fef03 | 74 | * |
kevman | 0:38ceb79fef03 | 75 | * #### Undefined behavior |
kevman | 0:38ceb79fef03 | 76 | * - Calling wait if the mutex is not locked by the current thread is undefined |
kevman | 0:38ceb79fef03 | 77 | * behavior. |
kevman | 0:38ceb79fef03 | 78 | * - The order in which waiting threads acquire the condition variable's |
kevman | 0:38ceb79fef03 | 79 | * mutex after `ConditionVariable::notify_all` is called is undefined. |
kevman | 0:38ceb79fef03 | 80 | * - The behavior of `ConditionVariable::wait` and `ConditionVariable::wait_for` |
kevman | 0:38ceb79fef03 | 81 | * is undefined if the condition variable's mutex is locked more than once by |
kevman | 0:38ceb79fef03 | 82 | * the calling thread. |
kevman | 0:38ceb79fef03 | 83 | * |
kevman | 0:38ceb79fef03 | 84 | * @note Synchronization level: Thread safe |
kevman | 0:38ceb79fef03 | 85 | * |
kevman | 0:38ceb79fef03 | 86 | * Example: |
kevman | 0:38ceb79fef03 | 87 | * |
kevman | 0:38ceb79fef03 | 88 | * @code |
kevman | 0:38ceb79fef03 | 89 | * #include "mbed.h" |
kevman | 0:38ceb79fef03 | 90 | * |
kevman | 0:38ceb79fef03 | 91 | * Mutex mutex; |
kevman | 0:38ceb79fef03 | 92 | * ConditionVariable cv(mutex); |
kevman | 0:38ceb79fef03 | 93 | * |
kevman | 0:38ceb79fef03 | 94 | * // These variables are protected by locking the mutex. |
kevman | 0:38ceb79fef03 | 95 | * uint32_t work_count = 0; |
kevman | 0:38ceb79fef03 | 96 | * bool done = false; |
kevman | 0:38ceb79fef03 | 97 | * |
kevman | 0:38ceb79fef03 | 98 | * void worker_thread() |
kevman | 0:38ceb79fef03 | 99 | * { |
kevman | 0:38ceb79fef03 | 100 | * // Acquire lock on mutex before accessing protected variables and waiting. |
kevman | 0:38ceb79fef03 | 101 | * mutex.lock(); |
kevman | 0:38ceb79fef03 | 102 | * |
kevman | 0:38ceb79fef03 | 103 | * while (done == false) { |
kevman | 0:38ceb79fef03 | 104 | * printf("Worker thread: Count: %lu\r\n", work_count); |
kevman | 0:38ceb79fef03 | 105 | * |
kevman | 0:38ceb79fef03 | 106 | * // Wait for main thread to notify the condition variable. |
kevman | 0:38ceb79fef03 | 107 | * printf("Worker thread: Waiting\r\n"); |
kevman | 0:38ceb79fef03 | 108 | * cv.wait(); |
kevman | 0:38ceb79fef03 | 109 | * } |
kevman | 0:38ceb79fef03 | 110 | * |
kevman | 0:38ceb79fef03 | 111 | * printf("Worker: Exiting\r\n"); |
kevman | 0:38ceb79fef03 | 112 | * |
kevman | 0:38ceb79fef03 | 113 | * // The condition variable acquires the lock when exiting the `wait` function. |
kevman | 0:38ceb79fef03 | 114 | * // Unlock mutex when exiting the thread. |
kevman | 0:38ceb79fef03 | 115 | * mutex.unlock(); |
kevman | 0:38ceb79fef03 | 116 | * } |
kevman | 0:38ceb79fef03 | 117 | * |
kevman | 0:38ceb79fef03 | 118 | * int main() |
kevman | 0:38ceb79fef03 | 119 | * { |
kevman | 0:38ceb79fef03 | 120 | * Thread thread; |
kevman | 0:38ceb79fef03 | 121 | * thread.start(worker_thread); |
kevman | 0:38ceb79fef03 | 122 | * |
kevman | 0:38ceb79fef03 | 123 | * for (int i = 0; i < 5; i++) { |
kevman | 0:38ceb79fef03 | 124 | * // Acquire lock on mutex before modifying variables and notifying. |
kevman | 0:38ceb79fef03 | 125 | * mutex.lock(); |
kevman | 0:38ceb79fef03 | 126 | * |
kevman | 0:38ceb79fef03 | 127 | * // Change count and notify waiters. |
kevman | 0:38ceb79fef03 | 128 | * work_count++; |
kevman | 0:38ceb79fef03 | 129 | * printf("Main thread: Set count to: %lu\r\n", work_count); |
kevman | 0:38ceb79fef03 | 130 | * printf("Main thread: Notifying worker thread\r\n"); |
kevman | 0:38ceb79fef03 | 131 | * cv.notify_all(); |
kevman | 0:38ceb79fef03 | 132 | * |
kevman | 0:38ceb79fef03 | 133 | * // Mutex must be unlocked before the worker thread can acquire it. |
kevman | 0:38ceb79fef03 | 134 | * mutex.unlock(); |
kevman | 0:38ceb79fef03 | 135 | * |
kevman | 0:38ceb79fef03 | 136 | * wait(1.0); |
kevman | 0:38ceb79fef03 | 137 | * } |
kevman | 0:38ceb79fef03 | 138 | * |
kevman | 0:38ceb79fef03 | 139 | * // Change done and notify waiters of this. |
kevman | 0:38ceb79fef03 | 140 | * mutex.lock(); |
kevman | 0:38ceb79fef03 | 141 | * done = true; |
kevman | 0:38ceb79fef03 | 142 | * cv.notify_all(); |
kevman | 0:38ceb79fef03 | 143 | * mutex.unlock(); |
kevman | 0:38ceb79fef03 | 144 | * |
kevman | 0:38ceb79fef03 | 145 | * thread.join(); |
kevman | 0:38ceb79fef03 | 146 | * |
kevman | 0:38ceb79fef03 | 147 | * printf("Main: Exiting\r\n"); |
kevman | 0:38ceb79fef03 | 148 | * } |
kevman | 0:38ceb79fef03 | 149 | * @endcode |
kevman | 0:38ceb79fef03 | 150 | */ |
kevman | 0:38ceb79fef03 | 151 | |
kevman | 0:38ceb79fef03 | 152 | class ConditionVariable : private mbed::NonCopyable<ConditionVariable> { |
kevman | 0:38ceb79fef03 | 153 | public: |
kevman | 0:38ceb79fef03 | 154 | /** Create and initialize a ConditionVariable object. |
kevman | 0:38ceb79fef03 | 155 | * |
kevman | 0:38ceb79fef03 | 156 | * @note You cannot call this function from ISR context. |
kevman | 0:38ceb79fef03 | 157 | */ |
kevman | 0:38ceb79fef03 | 158 | ConditionVariable(Mutex &mutex); |
kevman | 0:38ceb79fef03 | 159 | |
kevman | 0:38ceb79fef03 | 160 | /** Wait for a notification. |
kevman | 0:38ceb79fef03 | 161 | * |
kevman | 0:38ceb79fef03 | 162 | * Wait causes the current thread to block until the condition variable |
kevman | 0:38ceb79fef03 | 163 | * receives a notification from another thread. |
kevman | 0:38ceb79fef03 | 164 | * |
kevman | 0:38ceb79fef03 | 165 | * @note - The thread calling this function must be the owner of the |
kevman | 0:38ceb79fef03 | 166 | * ConditionVariable's mutex, and it must be locked exactly once. |
kevman | 0:38ceb79fef03 | 167 | * |
kevman | 0:38ceb79fef03 | 168 | * @note - Spurious notifications can occur, so the caller of this API |
kevman | 0:38ceb79fef03 | 169 | * should check to make sure the condition the caller is waiting on has |
kevman | 0:38ceb79fef03 | 170 | * been met. |
kevman | 0:38ceb79fef03 | 171 | * |
kevman | 0:38ceb79fef03 | 172 | * @note - The current thread releases the lock while inside the wait |
kevman | 0:38ceb79fef03 | 173 | * function and reacquires it upon exiting the function. |
kevman | 0:38ceb79fef03 | 174 | * |
kevman | 0:38ceb79fef03 | 175 | * Example: |
kevman | 0:38ceb79fef03 | 176 | * @code |
kevman | 0:38ceb79fef03 | 177 | * mutex.lock(); |
kevman | 0:38ceb79fef03 | 178 | * |
kevman | 0:38ceb79fef03 | 179 | * while (!condition_met) { |
kevman | 0:38ceb79fef03 | 180 | * cond.wait(); |
kevman | 0:38ceb79fef03 | 181 | * } |
kevman | 0:38ceb79fef03 | 182 | * |
kevman | 0:38ceb79fef03 | 183 | * function_to_handle_condition(); |
kevman | 0:38ceb79fef03 | 184 | * |
kevman | 0:38ceb79fef03 | 185 | * mutex.unlock(); |
kevman | 0:38ceb79fef03 | 186 | * @endcode |
kevman | 0:38ceb79fef03 | 187 | * |
kevman | 0:38ceb79fef03 | 188 | * @note You cannot call this function from ISR context. |
kevman | 0:38ceb79fef03 | 189 | */ |
kevman | 0:38ceb79fef03 | 190 | void wait(); |
kevman | 0:38ceb79fef03 | 191 | |
kevman | 0:38ceb79fef03 | 192 | /** Wait for a notification until the specified time. |
kevman | 0:38ceb79fef03 | 193 | * |
kevman | 0:38ceb79fef03 | 194 | * Wait until causes the current thread to block until the condition |
kevman | 0:38ceb79fef03 | 195 | * variable is notified, or a specific time given by millisec parameter is |
kevman | 0:38ceb79fef03 | 196 | * reached. |
kevman | 0:38ceb79fef03 | 197 | * |
kevman | 0:38ceb79fef03 | 198 | * @param millisec Absolute end time referenced to `Kernel::get_ms_count()` |
kevman | 0:38ceb79fef03 | 199 | * @return `true` if a timeout occurred, `false` otherwise. |
kevman | 0:38ceb79fef03 | 200 | * |
kevman | 0:38ceb79fef03 | 201 | * @note - The thread calling this function must be the owner of the |
kevman | 0:38ceb79fef03 | 202 | * ConditionVariable's mutex, and it must be locked exactly once. |
kevman | 0:38ceb79fef03 | 203 | * |
kevman | 0:38ceb79fef03 | 204 | * @note - Spurious notifications can occur, so the caller of this API |
kevman | 0:38ceb79fef03 | 205 | * should check to make sure the condition the caller is waiting on has |
kevman | 0:38ceb79fef03 | 206 | * been met. |
kevman | 0:38ceb79fef03 | 207 | * |
kevman | 0:38ceb79fef03 | 208 | * @note - The current thread releases the lock while inside the wait |
kevman | 0:38ceb79fef03 | 209 | * function and reacquires it upon exiting the function. |
kevman | 0:38ceb79fef03 | 210 | * |
kevman | 0:38ceb79fef03 | 211 | * Example: |
kevman | 0:38ceb79fef03 | 212 | * @code |
kevman | 0:38ceb79fef03 | 213 | * mutex.lock(); |
kevman | 0:38ceb79fef03 | 214 | * uint64_t end_time = Kernel::get_ms_count() + COND_WAIT_TIMEOUT; |
kevman | 0:38ceb79fef03 | 215 | * |
kevman | 0:38ceb79fef03 | 216 | * while (!condition_met) { |
kevman | 0:38ceb79fef03 | 217 | * if (cond.wait_until(end_time)) { |
kevman | 0:38ceb79fef03 | 218 | * break; |
kevman | 0:38ceb79fef03 | 219 | * } |
kevman | 0:38ceb79fef03 | 220 | * } |
kevman | 0:38ceb79fef03 | 221 | * |
kevman | 0:38ceb79fef03 | 222 | * if (condition_met) { |
kevman | 0:38ceb79fef03 | 223 | * function_to_handle_condition(); |
kevman | 0:38ceb79fef03 | 224 | * } |
kevman | 0:38ceb79fef03 | 225 | * |
kevman | 0:38ceb79fef03 | 226 | * mutex.unlock(); |
kevman | 0:38ceb79fef03 | 227 | * @endcode |
kevman | 0:38ceb79fef03 | 228 | * |
kevman | 0:38ceb79fef03 | 229 | * @note You cannot call this function from ISR context. |
kevman | 0:38ceb79fef03 | 230 | */ |
kevman | 0:38ceb79fef03 | 231 | bool wait_until(uint64_t millisec); |
kevman | 0:38ceb79fef03 | 232 | |
kevman | 0:38ceb79fef03 | 233 | /** Wait for a notification or timeout. |
kevman | 0:38ceb79fef03 | 234 | * |
kevman | 0:38ceb79fef03 | 235 | * `Wait for` causes the current thread to block until the condition |
kevman | 0:38ceb79fef03 | 236 | * variable receives a notification from another thread, or the timeout |
kevman | 0:38ceb79fef03 | 237 | * specified by the millisec parameter is reached. |
kevman | 0:38ceb79fef03 | 238 | * |
kevman | 0:38ceb79fef03 | 239 | * @param millisec Timeout value or osWaitForever in case of no timeout. |
kevman | 0:38ceb79fef03 | 240 | * @return `true` if a timeout occurred, `false` otherwise. |
kevman | 0:38ceb79fef03 | 241 | * |
kevman | 0:38ceb79fef03 | 242 | * @note - The thread calling this function must be the owner of the |
kevman | 0:38ceb79fef03 | 243 | * ConditionVariable's mutex, and it must be locked exactly once. |
kevman | 0:38ceb79fef03 | 244 | * |
kevman | 0:38ceb79fef03 | 245 | * @note - Spurious notifications can occur, so the caller of this API |
kevman | 0:38ceb79fef03 | 246 | * should check to make sure the condition the caller is waiting on has |
kevman | 0:38ceb79fef03 | 247 | * been met. |
kevman | 0:38ceb79fef03 | 248 | * |
kevman | 0:38ceb79fef03 | 249 | * @note - The current thread releases the lock while inside the wait |
kevman | 0:38ceb79fef03 | 250 | * function and reacquire it upon exiting the function. |
kevman | 0:38ceb79fef03 | 251 | * |
kevman | 0:38ceb79fef03 | 252 | * Example: |
kevman | 0:38ceb79fef03 | 253 | * @code |
kevman | 0:38ceb79fef03 | 254 | * mutex.lock(); |
kevman | 0:38ceb79fef03 | 255 | * |
kevman | 0:38ceb79fef03 | 256 | * while (!condition_met) { |
kevman | 0:38ceb79fef03 | 257 | * cond.wait_for(MAX_SLEEP_TIME); |
kevman | 0:38ceb79fef03 | 258 | * if (!condition_met) { |
kevman | 0:38ceb79fef03 | 259 | * do_other_work_while_condition_false(); |
kevman | 0:38ceb79fef03 | 260 | * } |
kevman | 0:38ceb79fef03 | 261 | * } |
kevman | 0:38ceb79fef03 | 262 | * |
kevman | 0:38ceb79fef03 | 263 | * if (condition_met) { |
kevman | 0:38ceb79fef03 | 264 | * function_to_handle_condition(); |
kevman | 0:38ceb79fef03 | 265 | * } |
kevman | 0:38ceb79fef03 | 266 | * |
kevman | 0:38ceb79fef03 | 267 | * mutex.unlock(); |
kevman | 0:38ceb79fef03 | 268 | * @endcode |
kevman | 0:38ceb79fef03 | 269 | * |
kevman | 0:38ceb79fef03 | 270 | * @note You cannot call this function from ISR context. |
kevman | 0:38ceb79fef03 | 271 | */ |
kevman | 0:38ceb79fef03 | 272 | bool wait_for(uint32_t millisec); |
kevman | 0:38ceb79fef03 | 273 | |
kevman | 0:38ceb79fef03 | 274 | /** Notify one waiter on this condition variable that a condition changed. |
kevman | 0:38ceb79fef03 | 275 | * |
kevman | 0:38ceb79fef03 | 276 | * This function unblocks one of the threads waiting for the condition |
kevman | 0:38ceb79fef03 | 277 | * variable. |
kevman | 0:38ceb79fef03 | 278 | * |
kevman | 0:38ceb79fef03 | 279 | * @note - The thread calling this function must be the owner of the |
kevman | 0:38ceb79fef03 | 280 | * ConditionVariable's mutex. |
kevman | 0:38ceb79fef03 | 281 | * |
kevman | 0:38ceb79fef03 | 282 | * @note - The thread that is unblocked on ConditionVariable::notify_one is |
kevman | 0:38ceb79fef03 | 283 | * undefined if there are multiple waiters. |
kevman | 0:38ceb79fef03 | 284 | * |
kevman | 0:38ceb79fef03 | 285 | * @note You cannot call this function from ISR context. |
kevman | 0:38ceb79fef03 | 286 | */ |
kevman | 0:38ceb79fef03 | 287 | void notify_one(); |
kevman | 0:38ceb79fef03 | 288 | |
kevman | 0:38ceb79fef03 | 289 | /** Notify all waiters on this condition variable that a condition changed. |
kevman | 0:38ceb79fef03 | 290 | * |
kevman | 0:38ceb79fef03 | 291 | * This function unblocks all of the threads waiting for the condition |
kevman | 0:38ceb79fef03 | 292 | * variable. |
kevman | 0:38ceb79fef03 | 293 | * |
kevman | 0:38ceb79fef03 | 294 | * @note - The thread calling this function must be the owner of the |
kevman | 0:38ceb79fef03 | 295 | * ConditionVariable's mutex. |
kevman | 0:38ceb79fef03 | 296 | * |
kevman | 0:38ceb79fef03 | 297 | * @note - If there are one or more waiters and one or more threads |
kevman | 0:38ceb79fef03 | 298 | * attempting to acquire the condition variable's mutex the order in which |
kevman | 0:38ceb79fef03 | 299 | * the mutex is acquired is undefined. |
kevman | 0:38ceb79fef03 | 300 | * |
kevman | 0:38ceb79fef03 | 301 | * @note You cannot call this function from ISR context. |
kevman | 0:38ceb79fef03 | 302 | */ |
kevman | 0:38ceb79fef03 | 303 | void notify_all(); |
kevman | 0:38ceb79fef03 | 304 | |
kevman | 0:38ceb79fef03 | 305 | /** ConditionVariable destructor. |
kevman | 0:38ceb79fef03 | 306 | * |
kevman | 0:38ceb79fef03 | 307 | * @note You cannot call this function from ISR context. |
kevman | 0:38ceb79fef03 | 308 | */ |
kevman | 0:38ceb79fef03 | 309 | ~ConditionVariable(); |
kevman | 0:38ceb79fef03 | 310 | |
kevman | 0:38ceb79fef03 | 311 | #if !defined(DOXYGEN_ONLY) |
kevman | 0:38ceb79fef03 | 312 | protected: |
kevman | 0:38ceb79fef03 | 313 | struct Waiter { |
kevman | 0:38ceb79fef03 | 314 | Waiter(); |
kevman | 0:38ceb79fef03 | 315 | Semaphore sem; |
kevman | 0:38ceb79fef03 | 316 | Waiter *prev; |
kevman | 0:38ceb79fef03 | 317 | Waiter *next; |
kevman | 0:38ceb79fef03 | 318 | bool in_list; |
kevman | 0:38ceb79fef03 | 319 | }; |
kevman | 0:38ceb79fef03 | 320 | |
kevman | 0:38ceb79fef03 | 321 | static void _add_wait_list(Waiter **wait_list, Waiter *waiter); |
kevman | 0:38ceb79fef03 | 322 | static void _remove_wait_list(Waiter **wait_list, Waiter *waiter); |
kevman | 0:38ceb79fef03 | 323 | Mutex &_mutex; |
kevman | 0:38ceb79fef03 | 324 | Waiter *_wait_list; |
kevman | 0:38ceb79fef03 | 325 | #endif // !defined(DOXYGEN_ONLY) |
kevman | 0:38ceb79fef03 | 326 | }; |
kevman | 0:38ceb79fef03 | 327 | |
kevman | 0:38ceb79fef03 | 328 | } |
kevman | 0:38ceb79fef03 | 329 | #endif |
kevman | 0:38ceb79fef03 | 330 | |
kevman | 0:38ceb79fef03 | 331 | /** @}*/ |