SharedMemory.hpp

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#ifndef SHARED_MEMORY_HPP
#define SHARED_MEMORY_HPP
 
#include <thread>
#include <mutex>
#include <memory>
#include <vector>
#include <utility>
#include <fcntl.h>
#include <map>
 
// shared mutex
#include <semaphore.h>
 
namespace com {
 
  struct SharedData {
    int32_t tv_sec;
    uint32_t tv_nsec;
    uint8_t* data;
    size_t   dataSize;
  };
 
  class SharedMemory {
    private:
    std::string m_shmName;
    std::string m_semaphoreName;
    int m_shmAddress = -1;
    int m_shmSize = -1;
 
    sem_t* m_semaphore = nullptr;
    void* m_sharedArea = nullptr;
 
    uint32_t m_lastDataSec = 0;
    uint32_t m_lastDataNSec = 0;
 
    public:
    SharedMemory(std::string name);
    SharedMemory() = delete;
    ~SharedMemory();
 
    size_t get_data_size();
 
    bool allocate(size_t sizeBytes);
    bool deallocate();
 
    bool write_mutexed(com::SharedData const& data);
 
    bool is_new_data_available();
    size_t read_mutexed(com::SharedData& data, size_t sizeToRead);
 
    private:
    bool acquire_semaphore(bool timedWait = false);
    bool release_semaphore();
  };
 
}
 
#endif