ShmSystemV.h

#ifndef SHMSYSTEMV_H_
#define SHMSYSTEMV_H_

#include <sys/ipc.h>
#include <sys/types.h>

#include "ADIOSConfig.h"
#include "core/Capsule.h"

namespace adios
{

/**
 * Buffer and Metadata are allocated in virtual memory using interprocess
 * communication (IPC) of Unix's System V
 */
class ShmSystemV : public Capsule
{

public:
    /**
     * Create a Capsule in shared memory using System V shm API
     * @param accessMode
     * @param pathName used to create the key as a unique identifier
     * @param dataSize size of allocated memory segment for data
     * @param metadataSize size of allocated memory segment for metadata
     * @param debugMode true: extra checks, slower
     */
    ShmSystemV(std::string accessMode, int rankMPI, const std::string &pathName,
               size_t dataSize, size_t metadataSize, bool debugMode = false);

    ~ShmSystemV() = default;

    char *GetData();     ///< return the pointer to the raw data buffer
    char *GetMetadata(); ///< return the pointer to the raw metadata buffer

    size_t GetDataSize() const;     ///< get current data buffer size
    size_t GetMetadataSize() const; ///< get current metadata buffer size

private:
    char *m_Data = nullptr;  ///< reference to a shared memory data buffer
                             /// created with shmget
    const size_t m_DataSize; ///< size of the allocated shared memory segment
    key_t m_DataKey; ///< key associated with the data buffer, created with ftok
    int m_DataShmID; ///< data shared memory buffer id

    char *m_Metadata =
        nullptr; ///< reference to a shared memory metadata buffer
                 /// created with shmget
    const size_t
        m_MetadataSize;  ///< size of the allocated shared memory segment
    key_t m_MetadataKey; ///< key associated with the metadata buffer, created
                         /// with ftok
    int m_MetadataShmID; ///< metadata shared memory buffer id

    void CheckShm() const; ///< checks if all shared memory allocations are
                           /// correct, throws std::bad_alloc, called from
                           /// constructor if debug mode is true
};

} // end namespace adios

#endif /* SHMSYSTEMV_H_ */