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117 lines
3.2 KiB
C++
117 lines
3.2 KiB
C++
/*
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* Copyright (C) 2015 Hamburg University of Applied Sciences (HAW)
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup cpp11-compat
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* @{
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*
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* @file
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* @brief C++11 condition variable drop in replacement
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*
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* @author Raphael Hiesgen <raphael.hiesgen (at) haw-hamburg.de>
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*
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* @}
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*/
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#include <stdexcept>
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#include <system_error>
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#include "irq.h"
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#include "sched.h"
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#include "thread.h"
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#include "timex.h"
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#include "xtimer.h"
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#include "priority_queue.h"
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#include "riot/condition_variable.hpp"
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using namespace std::chrono;
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namespace riot {
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condition_variable::~condition_variable() { m_queue.first = NULL; }
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void condition_variable::notify_one() noexcept {
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unsigned old_state = irq_disable();
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priority_queue_node_t* head = priority_queue_remove_head(&m_queue);
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int other_prio = -1;
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if (head != NULL) {
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thread_t* other_thread = (thread_t*)sched_threads[head->data];
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if (other_thread) {
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other_prio = other_thread->priority;
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sched_set_status(other_thread, STATUS_PENDING);
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}
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head->data = -1u;
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}
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irq_restore(old_state);
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if (other_prio >= 0) {
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sched_switch(other_prio);
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}
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}
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void condition_variable::notify_all() noexcept {
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unsigned old_state = irq_disable();
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int other_prio = -1;
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while (true) {
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priority_queue_node_t* head = priority_queue_remove_head(&m_queue);
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if (head == NULL) {
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break;
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}
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thread_t* other_thread = (thread_t*)sched_threads[head->data];
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if (other_thread) {
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auto max_prio
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= [](int a, int b) { return (a < 0) ? b : ((a < b) ? a : b); };
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other_prio = max_prio(other_prio, other_thread->priority);
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sched_set_status(other_thread, STATUS_PENDING);
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}
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head->data = -1u;
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}
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irq_restore(old_state);
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if (other_prio >= 0) {
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sched_switch(other_prio);
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}
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}
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void condition_variable::wait(unique_lock<mutex>& lock) noexcept {
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priority_queue_node_t n;
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n.priority = sched_active_thread->priority;
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n.data = sched_active_pid;
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n.next = NULL;
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// the signaling thread may not hold the mutex, the queue is not thread safe
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unsigned old_state = irq_disable();
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priority_queue_add(&m_queue, &n);
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irq_restore(old_state);
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mutex_unlock_and_sleep(lock.mutex()->native_handle());
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if (n.data != -1u) {
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// on signaling n.data is set to -1u
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// if it isn't set, then the wakeup is either spurious or a timer wakeup
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old_state = irq_disable();
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priority_queue_remove(&m_queue, &n);
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irq_restore(old_state);
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}
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mutex_lock(lock.mutex()->native_handle());
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}
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cv_status condition_variable::wait_until(unique_lock<mutex>& lock,
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const time_point& timeout_time) {
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xtimer_t timer;
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// todo: use function to wait for absolute timepoint once available
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timex_t before;
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xtimer_now_timex(&before);
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auto diff = timex_sub(timeout_time.native_handle(), before);
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xtimer_set_wakeup(&timer, timex_uint64(diff), sched_active_pid);
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wait(lock);
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timex_t after;
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xtimer_now_timex(&after);
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xtimer_remove(&timer);
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auto cmp = timex_cmp(after, timeout_time.native_handle());
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return cmp < 1 ? cv_status::no_timeout : cv_status::timeout;
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}
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} // namespace riot
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