amiro-os / include / amiro / util / rwlock.hpp @ c9fa414d
History | View | Annotate | Download (3.016 KB)
| 1 |
#ifndef AMIRO_RWLOCK_H_
|
|---|---|
| 2 |
#define AMIRO_RWLOCK_H_
|
| 3 |
|
| 4 |
#include <ch.hpp> |
| 5 |
|
| 6 |
namespace amiro {
|
| 7 |
|
| 8 |
/**
|
| 9 |
* @brief An enhanced mutex with parallel read but exclusive write capabilities
|
| 10 |
*/
|
| 11 |
class RWLock |
| 12 |
{
|
| 13 |
public:
|
| 14 |
/**
|
| 15 |
* @brief An enum to specify the favoritism of the RWLock
|
| 16 |
*/
|
| 17 |
enum Favor : bool { |
| 18 |
FAVOR_READERS = false, /**< Favors readers, even if writers are waiting */ |
| 19 |
FAVOR_WRITERS = true, /**< Favors writers and holds new readers back */ |
| 20 |
}; |
| 21 |
|
| 22 |
/**
|
| 23 |
* @brief An enum to specify what to wait for in the tryLockReading() and tryLockWriting() methods.
|
| 24 |
*/
|
| 25 |
enum WaitingType : uint8_t {
|
| 26 |
WAIT_FOR_NONE = 0, /**< does not block at all */ |
| 27 |
WAIT_FOR_MUTEX = 1, /**< blocks at the mutex */ |
| 28 |
WAIT_FOR_QUEUE = 2, /**< waits for the queues */ |
| 29 |
}; |
| 30 |
|
| 31 |
private:
|
| 32 |
/**
|
| 33 |
* @brief A status struct holding the current configuration of the RWLock.
|
| 34 |
*/
|
| 35 |
struct AccessStatus {
|
| 36 |
uint8_t reader_count : 7; /**< The number of currently active readers (128 max) */ |
| 37 |
uint8_t favor : 1; /**< The currently selected favoritism */ |
| 38 |
}; |
| 39 |
|
| 40 |
chibios_rt::Mutex mutex; /**< A mutex lock used for synchronization */
|
| 41 |
chibios_rt::CondVar waiting_readers; /**< A condition variable for waiting readers */
|
| 42 |
chibios_rt::CondVar waiting_writers; /**< A condition variable for all waiting writers */
|
| 43 |
AccessStatus status; /**< The current status of the RWLock */
|
| 44 |
|
| 45 |
public:
|
| 46 |
/**
|
| 47 |
* @brief Constructor of the RWLock class.
|
| 48 |
* @param[in] favor The initial favoritism (default: FAVOR_WRITERS)
|
| 49 |
*/
|
| 50 |
explicit RWLock(const Favor favor = FAVOR_WRITERS); |
| 51 |
|
| 52 |
/**
|
| 53 |
* @brief Destructor of the RWLock class.
|
| 54 |
*/
|
| 55 |
virtual ~RWLock();
|
| 56 |
|
| 57 |
/**
|
| 58 |
* @brief Lock the RWLock as a reader (shared mode)
|
| 59 |
*/
|
| 60 |
void lockReading();
|
| 61 |
|
| 62 |
/**
|
| 63 |
* @brief Lock the RWLock as a writer (exclusive mode)
|
| 64 |
*/
|
| 65 |
void lockWriting();
|
| 66 |
|
| 67 |
/**
|
| 68 |
* @brief Try to lock the RWLock as a reader (shared mode) but do not block
|
| 69 |
* @param[in] wait Can be used to wait for the mutex to lock or the queue to be empty
|
| 70 |
* @return True if the RWLock was successfully locked; False if not
|
| 71 |
*/
|
| 72 |
bool tryLockReading(const WaitingType wait = WAIT_FOR_NONE); |
| 73 |
|
| 74 |
/**
|
| 75 |
* @brief Try to lock the RWLock as a writer (exclusive mode) but do not block
|
| 76 |
* @param[in] wait Can be used to wait for the mutex to lock or the queue to be empty
|
| 77 |
* @return True if the RWLock was successfully locked; False if not
|
| 78 |
*/
|
| 79 |
bool tryLockWriting(const WaitingType wait = WAIT_FOR_NONE); |
| 80 |
|
| 81 |
/**
|
| 82 |
* @brief Unlocks the RWLock.
|
| 83 |
* If it was locked in shared or exclusive mode is detected automatically.
|
| 84 |
*/
|
| 85 |
void unlock();
|
| 86 |
|
| 87 |
/**
|
| 88 |
* @brief Set the favoritism of the RWLock
|
| 89 |
* @param[in] favor Either FAVOR_READERS or FAVOR_WRITERS
|
| 90 |
*/
|
| 91 |
void setFavoritism(const Favor favor); |
| 92 |
|
| 93 |
/**
|
| 94 |
* @brief Try to set the favoritism of the RWLock but do not block
|
| 95 |
* @param[in] favor Either FAVOR_READERS or FAVOR_WRITERS
|
| 96 |
* @return True if the favoritism was successfully set; False if not
|
| 97 |
*/
|
| 98 |
bool trySetFavoritism(const Favor favor); |
| 99 |
|
| 100 |
}; |
| 101 |
|
| 102 |
} // end of namespace amiro
|
| 103 |
|
| 104 |
#endif // AMIRO_RWLOCK_H_ |
| 105 |
|