Denislam Valeev / Mbed OS Nucleo_rtos_basic

1

mbed-os/rtos/ConditionVariable.h@0:e056ac8fecf8, 2018-03-13 (annotated)

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valeyev
Date:
Tue Mar 13 07:17:50 2018 +0000
Revision:
0:e056ac8fecf8
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valeyev 0:e056ac8fecf8 1 /* mbed Microcontroller Library
valeyev 0:e056ac8fecf8 2 * Copyright (c) 2017-2017 ARM Limited
valeyev 0:e056ac8fecf8 3 *
valeyev 0:e056ac8fecf8 4 * Permission is hereby granted, free of charge, to any person obtaining a copy
valeyev 0:e056ac8fecf8 5 * of this software and associated documentation files (the "Software"), to deal
valeyev 0:e056ac8fecf8 6 * in the Software without restriction, including without limitation the rights
valeyev 0:e056ac8fecf8 7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
valeyev 0:e056ac8fecf8 8 * copies of the Software, and to permit persons to whom the Software is
valeyev 0:e056ac8fecf8 9 * furnished to do so, subject to the following conditions:
valeyev 0:e056ac8fecf8 10 *
valeyev 0:e056ac8fecf8 11 * The above copyright notice and this permission notice shall be included in
valeyev 0:e056ac8fecf8 12 * all copies or substantial portions of the Software.
valeyev 0:e056ac8fecf8 13 *
valeyev 0:e056ac8fecf8 14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
valeyev 0:e056ac8fecf8 15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
valeyev 0:e056ac8fecf8 16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
valeyev 0:e056ac8fecf8 17 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
valeyev 0:e056ac8fecf8 18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
valeyev 0:e056ac8fecf8 19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
valeyev 0:e056ac8fecf8 20 * SOFTWARE.
valeyev 0:e056ac8fecf8 21 */
valeyev 0:e056ac8fecf8 22 #ifndef CONDITIONVARIABLE_H
valeyev 0:e056ac8fecf8 23 #define CONDITIONVARIABLE_H
valeyev 0:e056ac8fecf8 24
valeyev 0:e056ac8fecf8 25 #include <stdint.h>
valeyev 0:e056ac8fecf8 26 #include "cmsis_os.h"
valeyev 0:e056ac8fecf8 27 #include "rtos/Mutex.h"
valeyev 0:e056ac8fecf8 28 #include "rtos/Semaphore.h"
valeyev 0:e056ac8fecf8 29
valeyev 0:e056ac8fecf8 30 #include "platform/NonCopyable.h"
valeyev 0:e056ac8fecf8 31
valeyev 0:e056ac8fecf8 32 namespace rtos {
valeyev 0:e056ac8fecf8 33 /** \addtogroup rtos */
valeyev 0:e056ac8fecf8 34 /** @{*/
valeyev 0:e056ac8fecf8 35
valeyev 0:e056ac8fecf8 36 struct Waiter;
valeyev 0:e056ac8fecf8 37
valeyev 0:e056ac8fecf8 38 /** This class provides a safe way to wait for or send notifications of condition changes
valeyev 0:e056ac8fecf8 39 *
valeyev 0:e056ac8fecf8 40 * This class is used in conjunction with a mutex to safely wait for or
valeyev 0:e056ac8fecf8 41 * notify waiters of condition changes to a resource accessible by multiple
valeyev 0:e056ac8fecf8 42 * threads.
valeyev 0:e056ac8fecf8 43 *
valeyev 0:e056ac8fecf8 44 * # Defined behavior
valeyev 0:e056ac8fecf8 45 * - All threads waiting on the condition variable wake when
valeyev 0:e056ac8fecf8 46 * ConditionVariable::notify_all is called.
valeyev 0:e056ac8fecf8 47 * - If one or more threads are waiting on the condition variable at least
valeyev 0:e056ac8fecf8 48 * one of them wakes when ConditionVariable::notify is called.
valeyev 0:e056ac8fecf8 49 *
valeyev 0:e056ac8fecf8 50 * # Undefined behavior
valeyev 0:e056ac8fecf8 51 * - The thread which is unblocked on ConditionVariable::notify_one is
valeyev 0:e056ac8fecf8 52 * undefined if there are multiple waiters.
valeyev 0:e056ac8fecf8 53 * - The order which in which waiting threads acquire the condition variable's
valeyev 0:e056ac8fecf8 54 * mutex after ConditionVariable::notify_all is called is undefined.
valeyev 0:e056ac8fecf8 55 * - When ConditionVariable::notify_one or ConditionVariable::notify_all is
valeyev 0:e056ac8fecf8 56 * called and there are one or more waiters and one or more threads attempting
valeyev 0:e056ac8fecf8 57 * to acquire the condition variable's mutex the order in which the mutex is
valeyev 0:e056ac8fecf8 58 * acquired is undefined.
valeyev 0:e056ac8fecf8 59 * - The behavior of ConditionVariable::wait and ConditionVariable::wait_for
valeyev 0:e056ac8fecf8 60 * is undefined if the condition variable's mutex is locked more than once by
valeyev 0:e056ac8fecf8 61 * the calling thread.
valeyev 0:e056ac8fecf8 62 * - Spurious notifications (not triggered by the application) can occur
valeyev 0:e056ac8fecf8 63 * and it is not defined when these occur.
valeyev 0:e056ac8fecf8 64 *
valeyev 0:e056ac8fecf8 65 * @note Synchronization level: Thread safe
valeyev 0:e056ac8fecf8 66 *
valeyev 0:e056ac8fecf8 67 * Example:
valeyev 0:e056ac8fecf8 68 * @code
valeyev 0:e056ac8fecf8 69 * #include "mbed.h"
valeyev 0:e056ac8fecf8 70 *
valeyev 0:e056ac8fecf8 71 * Mutex mutex;
valeyev 0:e056ac8fecf8 72 * ConditionVariable cond(mutex);
valeyev 0:e056ac8fecf8 73 *
valeyev 0:e056ac8fecf8 74 * // These variables are protected by locking mutex
valeyev 0:e056ac8fecf8 75 * uint32_t count = 0;
valeyev 0:e056ac8fecf8 76 * bool done = false;
valeyev 0:e056ac8fecf8 77 *
valeyev 0:e056ac8fecf8 78 * void worker_thread()
valeyev 0:e056ac8fecf8 79 * {
valeyev 0:e056ac8fecf8 80 * mutex.lock();
valeyev 0:e056ac8fecf8 81 * do {
valeyev 0:e056ac8fecf8 82 * printf("Worker: Count %lu\r\n", count);
valeyev 0:e056ac8fecf8 83 *
valeyev 0:e056ac8fecf8 84 * // Wait for a condition to change
valeyev 0:e056ac8fecf8 85 * cond.wait();
valeyev 0:e056ac8fecf8 86 *
valeyev 0:e056ac8fecf8 87 * } while (!done);
valeyev 0:e056ac8fecf8 88 * printf("Worker: Exiting\r\n");
valeyev 0:e056ac8fecf8 89 * mutex.unlock();
valeyev 0:e056ac8fecf8 90 * }
valeyev 0:e056ac8fecf8 91 *
valeyev 0:e056ac8fecf8 92 * int main() {
valeyev 0:e056ac8fecf8 93 * Thread thread;
valeyev 0:e056ac8fecf8 94 * thread.start(worker_thread);
valeyev 0:e056ac8fecf8 95 *
valeyev 0:e056ac8fecf8 96 * for (int i = 0; i < 5; i++) {
valeyev 0:e056ac8fecf8 97 *
valeyev 0:e056ac8fecf8 98 * mutex.lock();
valeyev 0:e056ac8fecf8 99 * // Change count and notify waiters of this
valeyev 0:e056ac8fecf8 100 * count++;
valeyev 0:e056ac8fecf8 101 * printf("Main: Set count to %lu\r\n", count);
valeyev 0:e056ac8fecf8 102 * cond.notify_all();
valeyev 0:e056ac8fecf8 103 * mutex.unlock();
valeyev 0:e056ac8fecf8 104 *
valeyev 0:e056ac8fecf8 105 * wait(1.0);
valeyev 0:e056ac8fecf8 106 * }
valeyev 0:e056ac8fecf8 107 *
valeyev 0:e056ac8fecf8 108 * mutex.lock();
valeyev 0:e056ac8fecf8 109 * // Change done and notify waiters of this
valeyev 0:e056ac8fecf8 110 * done = true;
valeyev 0:e056ac8fecf8 111 * printf("Main: Set done\r\n");
valeyev 0:e056ac8fecf8 112 * cond.notify_all();
valeyev 0:e056ac8fecf8 113 * mutex.unlock();
valeyev 0:e056ac8fecf8 114 *
valeyev 0:e056ac8fecf8 115 * thread.join();
valeyev 0:e056ac8fecf8 116 * }
valeyev 0:e056ac8fecf8 117 * @endcode
valeyev 0:e056ac8fecf8 118 */
valeyev 0:e056ac8fecf8 119 class ConditionVariable : private mbed::NonCopyable<ConditionVariable> {
valeyev 0:e056ac8fecf8 120 public:
valeyev 0:e056ac8fecf8 121 /** Create and Initialize a ConditionVariable object
valeyev 0:e056ac8fecf8 122 *
valeyev 0:e056ac8fecf8 123 * @note You cannot call this function from ISR context.
valeyev 0:e056ac8fecf8 124 */
valeyev 0:e056ac8fecf8 125 ConditionVariable(Mutex &mutex);
valeyev 0:e056ac8fecf8 126
valeyev 0:e056ac8fecf8 127 /** Wait for a notification
valeyev 0:e056ac8fecf8 128 *
valeyev 0:e056ac8fecf8 129 * Wait until a notification occurs.
valeyev 0:e056ac8fecf8 130 *
valeyev 0:e056ac8fecf8 131 * @note - The thread calling this function must be the owner of the
valeyev 0:e056ac8fecf8 132 * ConditionVariable's mutex and it must be locked exactly once
valeyev 0:e056ac8fecf8 133 * @note - Spurious notifications can occur so the caller of this API
valeyev 0:e056ac8fecf8 134 * should check to make sure the condition they are waiting on has
valeyev 0:e056ac8fecf8 135 * been met
valeyev 0:e056ac8fecf8 136 *
valeyev 0:e056ac8fecf8 137 * Example:
valeyev 0:e056ac8fecf8 138 * @code
valeyev 0:e056ac8fecf8 139 * mutex.lock();
valeyev 0:e056ac8fecf8 140 * while (!condition_met) {
valeyev 0:e056ac8fecf8 141 * cond.wait();
valeyev 0:e056ac8fecf8 142 * }
valeyev 0:e056ac8fecf8 143 *
valeyev 0:e056ac8fecf8 144 * function_to_handle_condition();
valeyev 0:e056ac8fecf8 145 *
valeyev 0:e056ac8fecf8 146 * mutex.unlock();
valeyev 0:e056ac8fecf8 147 * @endcode
valeyev 0:e056ac8fecf8 148 *
valeyev 0:e056ac8fecf8 149 * @note You cannot call this function from ISR context.
valeyev 0:e056ac8fecf8 150 */
valeyev 0:e056ac8fecf8 151 void wait();
valeyev 0:e056ac8fecf8 152
valeyev 0:e056ac8fecf8 153 /** Wait for a notification until specified time
valeyev 0:e056ac8fecf8 154 *
valeyev 0:e056ac8fecf8 155 * @param millisec absolute end time referenced to Kernel::get_ms_count()
valeyev 0:e056ac8fecf8 156 * @return true if a timeout occurred, false otherwise.
valeyev 0:e056ac8fecf8 157 *
valeyev 0:e056ac8fecf8 158 * @note - The thread calling this function must be the owner of the
valeyev 0:e056ac8fecf8 159 * ConditionVariable's mutex and it must be locked exactly once
valeyev 0:e056ac8fecf8 160 * @note - Spurious notifications can occur so the caller of this API
valeyev 0:e056ac8fecf8 161 * should check to make sure the condition they are waiting on has
valeyev 0:e056ac8fecf8 162 * been met
valeyev 0:e056ac8fecf8 163 *
valeyev 0:e056ac8fecf8 164 * Example:
valeyev 0:e056ac8fecf8 165 * @code
valeyev 0:e056ac8fecf8 166 * mutex.lock();
valeyev 0:e056ac8fecf8 167 * uint64_t end_time = Kernel::get_ms_count() + COND_WAIT_TIMEOUT;
valeyev 0:e056ac8fecf8 168 *
valeyev 0:e056ac8fecf8 169 * while (!condition_met) {
valeyev 0:e056ac8fecf8 170 * if (cond.wait_until(end_time)) {
valeyev 0:e056ac8fecf8 171 * break;
valeyev 0:e056ac8fecf8 172 * }
valeyev 0:e056ac8fecf8 173 * }
valeyev 0:e056ac8fecf8 174 *
valeyev 0:e056ac8fecf8 175 * if (condition_met) {
valeyev 0:e056ac8fecf8 176 * function_to_handle_condition();
valeyev 0:e056ac8fecf8 177 * }
valeyev 0:e056ac8fecf8 178 *
valeyev 0:e056ac8fecf8 179 * mutex.unlock();
valeyev 0:e056ac8fecf8 180 * @endcode
valeyev 0:e056ac8fecf8 181 *
valeyev 0:e056ac8fecf8 182 * @note You cannot call this function from ISR context.
valeyev 0:e056ac8fecf8 183 */
valeyev 0:e056ac8fecf8 184 bool wait_until(uint64_t millisec);
valeyev 0:e056ac8fecf8 185
valeyev 0:e056ac8fecf8 186 /** Wait for a notification or timeout
valeyev 0:e056ac8fecf8 187 *
valeyev 0:e056ac8fecf8 188 * @param millisec timeout value or osWaitForever in case of no time-out.
valeyev 0:e056ac8fecf8 189 * @return true if a timeout occurred, false otherwise.
valeyev 0:e056ac8fecf8 190 *
valeyev 0:e056ac8fecf8 191 * @note - The thread calling this function must be the owner of the
valeyev 0:e056ac8fecf8 192 * ConditionVariable's mutex and it must be locked exactly once
valeyev 0:e056ac8fecf8 193 * @note - Spurious notifications can occur so the caller of this API
valeyev 0:e056ac8fecf8 194 * should check to make sure the condition they are waiting on has
valeyev 0:e056ac8fecf8 195 * been met
valeyev 0:e056ac8fecf8 196 *
valeyev 0:e056ac8fecf8 197 * Example:
valeyev 0:e056ac8fecf8 198 * @code
valeyev 0:e056ac8fecf8 199 * mutex.lock();
valeyev 0:e056ac8fecf8 200 *
valeyev 0:e056ac8fecf8 201 * while (!condition_met) {
valeyev 0:e056ac8fecf8 202 * cond.wait_for(MAX_SLEEP_TIME);
valeyev 0:e056ac8fecf8 203 * if (!condition_met) {
valeyev 0:e056ac8fecf8 204 * do_other_work_while_condition_false();
valeyev 0:e056ac8fecf8 205 * }
valeyev 0:e056ac8fecf8 206 * }
valeyev 0:e056ac8fecf8 207 *
valeyev 0:e056ac8fecf8 208 * if (condition_met) {
valeyev 0:e056ac8fecf8 209 * function_to_handle_condition();
valeyev 0:e056ac8fecf8 210 * }
valeyev 0:e056ac8fecf8 211 *
valeyev 0:e056ac8fecf8 212 * mutex.unlock();
valeyev 0:e056ac8fecf8 213 * @endcode
valeyev 0:e056ac8fecf8 214 *
valeyev 0:e056ac8fecf8 215 * @note You cannot call this function from ISR context.
valeyev 0:e056ac8fecf8 216 */
valeyev 0:e056ac8fecf8 217 bool wait_for(uint32_t millisec);
valeyev 0:e056ac8fecf8 218
valeyev 0:e056ac8fecf8 219 /** Notify one waiter on this condition variable that a condition changed.
valeyev 0:e056ac8fecf8 220 *
valeyev 0:e056ac8fecf8 221 * @note - The thread calling this function must be the owner of the ConditionVariable's mutex
valeyev 0:e056ac8fecf8 222 *
valeyev 0:e056ac8fecf8 223 * @note You cannot call this function from ISR context.
valeyev 0:e056ac8fecf8 224 */
valeyev 0:e056ac8fecf8 225 void notify_one();
valeyev 0:e056ac8fecf8 226
valeyev 0:e056ac8fecf8 227 /** Notify all waiters on this condition variable that a condition changed.
valeyev 0:e056ac8fecf8 228 *
valeyev 0:e056ac8fecf8 229 * @note - The thread calling this function must be the owner of the ConditionVariable's mutex
valeyev 0:e056ac8fecf8 230 *
valeyev 0:e056ac8fecf8 231 * @note You cannot call this function from ISR context.
valeyev 0:e056ac8fecf8 232 */
valeyev 0:e056ac8fecf8 233 void notify_all();
valeyev 0:e056ac8fecf8 234
valeyev 0:e056ac8fecf8 235 /** ConditionVariable destructor
valeyev 0:e056ac8fecf8 236 *
valeyev 0:e056ac8fecf8 237 * @note You cannot call this function from ISR context.
valeyev 0:e056ac8fecf8 238 */
valeyev 0:e056ac8fecf8 239 ~ConditionVariable();
valeyev 0:e056ac8fecf8 240
valeyev 0:e056ac8fecf8 241 protected:
valeyev 0:e056ac8fecf8 242 struct Waiter {
valeyev 0:e056ac8fecf8 243 Waiter();
valeyev 0:e056ac8fecf8 244 Semaphore sem;
valeyev 0:e056ac8fecf8 245 Waiter *prev;
valeyev 0:e056ac8fecf8 246 Waiter *next;
valeyev 0:e056ac8fecf8 247 bool in_list;
valeyev 0:e056ac8fecf8 248 };
valeyev 0:e056ac8fecf8 249
valeyev 0:e056ac8fecf8 250 static void _add_wait_list(Waiter **wait_list, Waiter *waiter);
valeyev 0:e056ac8fecf8 251 static void _remove_wait_list(Waiter **wait_list, Waiter *waiter);
valeyev 0:e056ac8fecf8 252 Mutex &_mutex;
valeyev 0:e056ac8fecf8 253 Waiter *_wait_list;
valeyev 0:e056ac8fecf8 254 };
valeyev 0:e056ac8fecf8 255
valeyev 0:e056ac8fecf8 256 }
valeyev 0:e056ac8fecf8 257 #endif
valeyev 0:e056ac8fecf8 258
valeyev 0:e056ac8fecf8 259 /** @}*/