amiro-os / include / amiro / util / rwlock.hpp @ 8c99e03a
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#ifndef AMIRO_RWLOCK_H_
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#define AMIRO_RWLOCK_H_
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#include <ch.hpp> |
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namespace amiro {
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/**
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* @brief An enhanced mutex with parallel read but exclusive write capabilities
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*/
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class RWLock |
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{
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public:
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/**
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* @brief An enum to specify the favoritism of the RWLock
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*/
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enum Favor : bool { |
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FAVOR_READERS = false, /**< Favors readers, even if writers are waiting */ |
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FAVOR_WRITERS = true, /**< Favors writers and holds new readers back */ |
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}; |
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/**
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* @brief An enum to specify what to wait for in the tryLockReading() and tryLockWriting() methods.
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*/
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enum WaitingType : uint8_t {
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WAIT_FOR_NONE = 0, /**< does not block at all */ |
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WAIT_FOR_MUTEX = 1, /**< blocks at the mutex */ |
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WAIT_FOR_QUEUE = 2, /**< waits for the queues */ |
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}; |
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private:
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/**
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* @brief A status struct holding the current configuration of the RWLock.
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*/
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struct AccessStatus {
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uint8_t reader_count : 7; /**< The number of currently active readers (128 max) */ |
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uint8_t favor : 1; /**< The currently selected favoritism */ |
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}; |
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chibios_rt::Mutex mutex; /**< A mutex lock used for synchronization */
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chibios_rt::CondVar waiting_readers; /**< A condition variable for waiting readers */
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chibios_rt::CondVar waiting_writers; /**< A condition variable for all waiting writers */
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AccessStatus status; /**< The current status of the RWLock */
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public:
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/**
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* @brief Constructor of the RWLock class.
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* @param[in] favor The initial favoritism (default: FAVOR_WRITERS)
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*/
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explicit RWLock(const Favor favor = FAVOR_WRITERS); |
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/**
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* @brief Destructor of the RWLock class.
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*/
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virtual ~RWLock();
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/**
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* @brief Lock the RWLock as a reader (shared mode)
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*/
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void lockReading();
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/**
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* @brief Lock the RWLock as a writer (exclusive mode)
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*/
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void lockWriting();
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/**
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* @brief Try to lock the RWLock as a reader (shared mode) but do not block
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* @param[in] wait Can be used to wait for the mutex to lock or the queue to be empty
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* @return True if the RWLock was successfully locked; False if not
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*/
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bool tryLockReading(const WaitingType wait = WAIT_FOR_NONE); |
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/**
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* @brief Try to lock the RWLock as a writer (exclusive mode) but do not block
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* @param[in] wait Can be used to wait for the mutex to lock or the queue to be empty
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* @return True if the RWLock was successfully locked; False if not
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*/
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bool tryLockWriting(const WaitingType wait = WAIT_FOR_NONE); |
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/**
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* @brief Unlocks the RWLock.
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* If it was locked in shared or exclusive mode is detected automatically.
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*/
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void unlock();
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/**
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* @brief Set the favoritism of the RWLock
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* @param[in] favor Either FAVOR_READERS or FAVOR_WRITERS
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*/
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void setFavoritism(const Favor favor); |
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/**
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* @brief Try to set the favoritism of the RWLock but do not block
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* @param[in] favor Either FAVOR_READERS or FAVOR_WRITERS
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* @return True if the favoritism was successfully set; False if not
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*/
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bool trySetFavoritism(const Favor favor); |
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}; |
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} // end of namespace amiro
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#endif // AMIRO_RWLOCK_H_ |
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