73 lines
2.7 KiB
C++
73 lines
2.7 KiB
C++
#ifndef FRAMEWORK_TASKS_SEMAPHOREIF_H_
|
|
#define FRAMEWORK_TASKS_SEMAPHOREIF_H_
|
|
#include <framework/returnvalues/FwClassIds.h>
|
|
#include <framework/returnvalues/HasReturnvaluesIF.h>
|
|
#include <cstdint>
|
|
|
|
/**
|
|
* @brief Generic interface for semaphores, which can be used to achieve
|
|
* task synchronization. This is a generic interface which can be
|
|
* used for both binary semaphores and counting semaphores.
|
|
* @details
|
|
* A semaphore is a synchronization primitive.
|
|
* See: https://en.wikipedia.org/wiki/Semaphore_(programming)
|
|
* A semaphore can be used to achieve task synchonization and track the
|
|
* availability of resources by using either the binary or the counting
|
|
* semaphore types.
|
|
*
|
|
* If mutual exlcusion of a resource is desired, a mutex should be used,
|
|
* which is a special form of a semaphore and has an own interface.
|
|
*/
|
|
class SemaphoreIF {
|
|
public:
|
|
virtual~ SemaphoreIF() {};
|
|
/**
|
|
* @brief Timeout value used for polling lock attempt.
|
|
* @details
|
|
* If the lock is not successfull, MUTEX_TIMEOUT will be returned
|
|
* immediately. Value needs to be defined in implementation.
|
|
*/
|
|
static const uint32_t POLLING;
|
|
/**
|
|
* @brief Timeout value used for permanent blocking lock attempt.
|
|
* @details
|
|
* The task will be blocked (indefinitely) until the mutex is unlocked.
|
|
* Value needs to be defined in implementation.
|
|
*/
|
|
static const uint32_t BLOCKING;
|
|
|
|
static const uint8_t INTERFACE_ID = CLASS_ID::SEMAPHORE_IF;
|
|
//! Semaphore timeout
|
|
static constexpr ReturnValue_t SEMAPHORE_TIMEOUT = MAKE_RETURN_CODE(1);
|
|
//! The current semaphore can not be given, because it is not owned
|
|
static constexpr ReturnValue_t SEMAPHORE_NOT_OWNED = MAKE_RETURN_CODE(2);
|
|
static constexpr ReturnValue_t SEMAPHORE_INVALID = MAKE_RETURN_CODE(3);
|
|
|
|
/**
|
|
* Generic call to acquire a semaphore.
|
|
* If there are no more semaphores to be taken (for a counting semaphore,
|
|
* a semaphore may be taken more than once), the taks will block
|
|
* for a maximum of timeoutMs while trying to acquire the semaphore.
|
|
* This can be used to achieve task synchrnization.
|
|
* @param timeoutMs
|
|
* @return - c RETURN_OK for successfull acquisition
|
|
*/
|
|
virtual ReturnValue_t acquire(uint32_t timeoutMs) = 0;
|
|
|
|
/**
|
|
* Corrensponding call to release a semaphore.
|
|
* @return -@c RETURN_OK for successfull release
|
|
*/
|
|
virtual ReturnValue_t release() = 0;
|
|
|
|
/**
|
|
* If the semaphore is a counting semaphore then the semaphores current
|
|
* count value is returned. If the semaphore is a binary semaphore then 1
|
|
* is returned if the semaphore is available, and 0 is returned if the
|
|
* semaphore is not available.
|
|
*/
|
|
virtual uint8_t getSemaphoreCounter() const = 0;
|
|
};
|
|
|
|
#endif /* FRAMEWORK_TASKS_SEMAPHOREIF_H_ */
|