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Diffstat (limited to 'include/distortos/ConditionVariable.hpp')
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diff --git a/include/distortos/ConditionVariable.hpp b/include/distortos/ConditionVariable.hpp new file mode 100644 index 0000000..6b7f869 --- /dev/null +++ b/include/distortos/ConditionVariable.hpp @@ -0,0 +1,304 @@ +/** + * \file + * \brief ConditionVariable class header + * + * \author Copyright (C) 2014-2015 Kamil Szczygiel http://www.distortec.com http://www.freddiechopin.info + * + * \par License + * This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not + * distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/. + */ + +#ifndef INCLUDE_DISTORTOS_CONDITIONVARIABLE_HPP_ +#define INCLUDE_DISTORTOS_CONDITIONVARIABLE_HPP_ + +#include "distortos/internal/scheduler/ThreadList.hpp" + +#include "distortos/TickClock.hpp" + +namespace distortos +{ + +class Mutex; + +/** + * \brief ConditionVariable is an advanced synchronization primitive + * + * Similar to std::condition_variable - http://en.cppreference.com/w/cpp/thread/condition_variable + * Similar to POSIX pthread_cond_t + * + * \ingroup synchronization + */ + +class ConditionVariable +{ +public: + + /** + * \brief ConditionVariable constructor + * + * Similar to std::condition_variable::condition_variable() - + * http://en.cppreference.com/w/cpp/thread/condition_variable/condition_variable + * Similar to pthread_cond_init() - http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_init.html + */ + + constexpr ConditionVariable() : + blockedList_{} + { + + } + + /** + * \brief Notifies all waiting threads. + * + * Similar to std::condition_variable::notify_all() - + * http://en.cppreference.com/w/cpp/thread/condition_variable/notify_all + * Similar to pthread_cond_broadcast() - + * http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_signal.html + * + * Unblocks all threads waiting on this condition variable. The notifying thread does not need to hold the same + * mutex as the one held by the waiting thread(s). + */ + + void notifyAll(); + + /** + * \brief Notifies one waiting thread. + * + * Similar to std::condition_variable::notify_one() - + * http://en.cppreference.com/w/cpp/thread/condition_variable/notify_one + * Similar to pthread_cond_signal() - + * http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_signal.html + * + * Unblocks one thread waiting on this condition variable. The notifying thread does not need to hold the same + * mutex as the one held by the waiting thread(s). + */ + + void notifyOne(); + + /** + * \brief Waits for notification. + * + * Similar to std::condition_variable::wait() - http://en.cppreference.com/w/cpp/thread/condition_variable/wait + * Similar to pthread_cond_wait() - http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_wait.html + * + * Atomically releases supplied mutex and blocks current thread until the condition variable is notified. The thread + * will be unblocked when notifyAll() or notifyOne() is executed. It may also be unblocked spuriously. When + * unblocked, regardless of the reason, lock is reacquired and wait exits. + * + * \param [in] mutex is a reference to mutex which must be owned by calling thread + * + * \return zero if the wait was completed successfully, error code otherwise: + * - EPERM - the mutex type is ErrorChecking or Recursive, and the current thread does not own the mutex; + */ + + int wait(Mutex& mutex); + + /** + * \brief Waits for predicate to become true. + * + * Similar to std::condition_variable::wait() - http://en.cppreference.com/w/cpp/thread/condition_variable/wait + * Similar to pthread_cond_wait() - http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_wait.html + * + * Overload for wait() which also checks the predicate. This function will return only if the predicate is true. + * + * \tparam Predicate is a type of functor to check the predicate + * + * \param [in] mutex is a reference to mutex which must be owned by calling thread + * \param [in] predicate is the predicate that will be checked + * + * \return zero if the wait was completed successfully, error code otherwise: + * - EPERM - the mutex type is ErrorChecking or Recursive, and the current thread does not own the mutex; + */ + + template<typename Predicate> + int wait(Mutex& mutex, Predicate predicate); + + /** + * \brief Waits for notification for given duration of time. + * + * Similar to std::condition_variable::wait_for() - + * http://en.cppreference.com/w/cpp/thread/condition_variable/wait_for + * Similar to pthread_cond_timedwait() - + * http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_timedwait.html# + * + * Atomically releases supplied mutex and blocks current thread until the condition variable is notified. The thread + * will be unblocked when notifyAll() or notifyOne() is executed or when given duration of time expires. It may also + * be unblocked spuriously. When unblocked, regardless of the reason, lock is reacquired and wait exits. + * + * \param [in] mutex is a reference to mutex which must be owned by calling thread + * \param [in] duration is the duration after which the wait for notification will be terminated + * + * \return zero if the wait was completed successfully, error code otherwise: + * - EPERM - the mutex type is ErrorChecking or Recursive, and the current thread does not own the mutex; + * - ETIMEDOUT - no notification was received before the specified timeout expired; + */ + + int waitFor(Mutex& mutex, TickClock::duration duration); + + /** + * \brief Waits for notification for given duration of time. + * + * Similar to std::condition_variable::wait_for() - + * http://en.cppreference.com/w/cpp/thread/condition_variable/wait_for + * Similar to pthread_cond_timedwait() - + * http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_timedwait.html# + * + * Template variant of waitFor(Mutex& mutex, TickClock::duration duration). + * + * \tparam Rep is type of tick counter + * \tparam Period is std::ratio type representing the tick period of the clock, in seconds + * + * \param [in] mutex is a reference to mutex which must be owned by calling thread + * \param [in] duration is the duration after which the wait for notification will be terminated + * + * \return zero if the wait was completed successfully, error code otherwise: + * - EPERM - the mutex type is ErrorChecking or Recursive, and the current thread does not own the mutex; + * - ETIMEDOUT - no notification was received before the specified timeout expired; + */ + + template<typename Rep, typename Period> + int waitFor(Mutex& mutex, const std::chrono::duration<Rep, Period> duration) + { + return waitFor(mutex, std::chrono::duration_cast<TickClock::duration>(duration)); + } + + /** + * \brief Waits for predicate to become true for given duration of time. + * + * Similar to std::condition_variable::wait_for() - + * http://en.cppreference.com/w/cpp/thread/condition_variable/wait_for + * Similar to pthread_cond_timedwait() - + * http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_timedwait.html# + * + * Overload for waitFor() which also checks the predicate. This function will return only if the predicate is true + * or when given duration of time expires. + * + * \tparam Rep is type of tick counter + * \tparam Period is std::ratio type representing the tick period of the clock, in seconds + * \tparam Predicate is a type of functor to check the predicate + * + * \param [in] mutex is a reference to mutex which must be owned by calling thread + * \param [in] duration is the duration after which the wait for notification will be terminated + * \param [in] predicate is the predicate that will be checked + * + * \return zero if the wait was completed successfully, error code otherwise: + * - EPERM - the mutex type is ErrorChecking or Recursive, and the current thread does not own the mutex; + * - ETIMEDOUT - no notification was received before the specified timeout expired; + */ + + template<typename Rep, typename Period, typename Predicate> + int waitFor(Mutex& mutex, const std::chrono::duration<Rep, Period> duration, Predicate predicate) + { + return waitUntil(mutex, TickClock::now() + duration + TickClock::duration{1}, std::move(predicate)); + } + + /** + * \brief Waits for notification until given time point. + * + * Similar to std::condition_variable::wait_until() - + * http://en.cppreference.com/w/cpp/thread/condition_variable/wait_until + * Similar to pthread_cond_timedwait() - + * http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_timedwait.html# + * + * Atomically releases supplied mutex and blocks current thread until the condition variable is notified. The thread + * will be unblocked when notifyAll() or notifyOne() is executed or when given time point is reached. It may also be + * unblocked spuriously. When unblocked, regardless of the reason, lock is reacquired and wait exits. + * + * \param [in] mutex is a reference to mutex which must be owned by calling thread + * \param [in] timePoint is the time point at which the wait for notification will be terminated + * + * \return zero if the wait was completed successfully, error code otherwise: + * - EPERM - the mutex type is ErrorChecking or Recursive, and the current thread does not own the mutex; + * - ETIMEDOUT - no notification was received before the specified timeout expired; + */ + + int waitUntil(Mutex& mutex, TickClock::time_point timePoint); + + /** + * \brief Waits for notification until given time point. + * + * Similar to std::condition_variable::wait_until() - + * http://en.cppreference.com/w/cpp/thread/condition_variable/wait_until + * Similar to pthread_cond_timedwait() - + * http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_timedwait.html# + * + * Template variant of waitUntil(Mutex& mutex, TickClock::time_point timePoint). + * + * \tparam Duration is a std::chrono::duration type used to measure duration + * + * \param [in] mutex is a reference to mutex which must be owned by calling thread + * \param [in] timePoint is the time point at which the wait for notification will be terminated + * + * \return zero if the wait was completed successfully, error code otherwise: + * - EPERM - the mutex type is ErrorChecking or Recursive, and the current thread does not own the mutex; + * - ETIMEDOUT - no notification was received before the specified timeout expired; + */ + + template<typename Duration> + int waitUntil(Mutex& mutex, const std::chrono::time_point<TickClock, Duration> timePoint) + { + return waitUntil(mutex, std::chrono::time_point_cast<TickClock::duration>(timePoint)); + } + + /** + * \brief Waits for predicate to become true until given time point. + * + * Similar to std::condition_variable::wait_until() - + * http://en.cppreference.com/w/cpp/thread/condition_variable/wait_until + * Similar to pthread_cond_timedwait() - + * http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_timedwait.html# + * + * Overload for waitUntil() which also checks the predicate. This function will return only if the predicate is true + * or when given time point is reached. + * + * \tparam Duration is a std::chrono::duration type used to measure duration + * \tparam Predicate is a type of functor to check the predicate + * + * \param [in] mutex is a reference to mutex which must be owned by calling thread + * \param [in] timePoint is the time point at which the wait for notification will be terminated + * \param [in] predicate is the predicate that will be checked + * + * \return zero if the wait was completed successfully, error code otherwise: + * - EPERM - the mutex type is ErrorChecking or Recursive, and the current thread does not own the mutex; + * - ETIMEDOUT - no notification was received before the specified timeout expired; + */ + + template<typename Duration, typename Predicate> + int waitUntil(Mutex& mutex, std::chrono::time_point<TickClock, Duration> timePoint, Predicate predicate); + +private: + + /// ThreadControlBlock objects blocked on this condition variable + internal::ThreadList blockedList_; +}; + +template<typename Predicate> +int ConditionVariable::wait(Mutex& mutex, Predicate predicate) +{ + while (predicate() == false) + { + const auto ret = wait(mutex); + if (ret != 0) + return ret; + } + + return 0; +} + +template<typename Duration, typename Predicate> +int ConditionVariable::waitUntil(Mutex& mutex, const std::chrono::time_point<TickClock, Duration> timePoint, Predicate predicate) +{ + while (predicate() == false) + { + const auto ret = waitUntil(mutex, timePoint); + if (ret != 0) + return ret; + } + + return 0; +} + +} // namespace distortos + +#endif // INCLUDE_DISTORTOS_CONDITIONVARIABLE_HPP_ |