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/*! \libinternal \file
 *  \brief Implements a DeviceEvent class for CUDA.
 *
 *  \author Aleksei Iupinov <a.yupinov@gmail.com>
 *  \author Andrey Alekseenko <al42and@gmail.com>
 *  \inlibraryapi
 */
#ifndef GMX_GPU_UTILS_DEVICE_EVENT_CUH
#define GMX_GPU_UTILS_DEVICE_EVENT_CUH

#include "gromacs/gpu_utils/cudautils.cuh"
#include "gromacs/gpu_utils/device_stream.h"
#include "gromacs/gpu_utils/gputraits.cuh"
#include "gromacs/utility/gmxassert.h"

#ifndef DOXYGEN

class DeviceEvent
{
public:
    DeviceEvent() : isMarked_(false)
    {
        cudaError_t stat = cudaEventCreateWithFlags(&event_, cudaEventDisableTiming);
        if (stat != cudaSuccess)
        {
            GMX_THROW(gmx::InternalError("cudaEventCreate failed: " + gmx::getDeviceErrorString(stat)));
        }
    }
    ~DeviceEvent() { cudaEventDestroy(event_); }
    // Disable copy, move, and assignment. Move can be allowed, but not needed yet.
    DeviceEvent& operator=(const DeviceEvent&) = delete;
    DeviceEvent(const DeviceEvent&)            = delete;
    DeviceEvent& operator=(DeviceEvent&&) = delete;
    DeviceEvent(DeviceEvent&&)            = delete;

    /*! \brief Marks the synchronization point in the \p stream.
     * Should be followed by waitForEvent().
     */
    inline void mark(const DeviceStream& deviceStream)
    {
        cudaError_t stat = cudaEventRecord(event_, deviceStream.stream());
        if (stat != cudaSuccess)
        {
            GMX_THROW(gmx::InternalError("cudaEventRecord failed: " + gmx::getDeviceErrorString(stat)));
        }
        isMarked_ = true;
    }
    //! Synchronizes the host thread on the marked event.
    inline void wait()
    {
        cudaError_t gmx_used_in_debug stat = cudaEventSynchronize(event_);
        if (stat != cudaSuccess)
        {
            GMX_THROW(gmx::InternalError("cudaEventSynchronize failed: " + gmx::getDeviceErrorString(stat)));
        }
    }
    //! Checks the completion of the underlying event.
    inline bool isReady()
    {
        cudaError_t stat = cudaEventQuery(event_);
        if (stat != cudaSuccess && stat != cudaErrorNotReady)
        {
            GMX_THROW(gmx::InternalError("cudaEventQuery failed: " + gmx::getDeviceErrorString(stat)));
        }
        return (stat == cudaSuccess);
    }
    //! Check if this event was marked
    inline bool isMarked() const { return isMarked_; }
    //! Enqueues a wait for the recorded event in stream \p stream
    inline void enqueueWait(const DeviceStream& deviceStream)
    {
        cudaError_t stat = cudaStreamWaitEvent(deviceStream.stream(), event_, 0);
        if (stat != cudaSuccess)
        {
            GMX_THROW(gmx::InternalError("cudaStreamWaitEvent failed: " + gmx::getDeviceErrorString(stat)));
        }
    }
    //! Reset the event
    inline void reset() { isMarked_ = false; }

private:
    cudaEvent_t event_;
    bool        isMarked_;
};

#endif

#endif