cuda_stream_manager.h

#ifndef CUDA_STREAM_MANAGER_H
#define CUDA_STREAM_MANAGER_H

#include <cuda_runtime.h>
#include <cublas_v2.h>
#include <helper_cuda.h> 

#include <cstdio>


class CudaStreamManager {
public:
    CudaStreamManager(const size_t num_expert_, const int device_) : num_expert(num_expert_), device(device_) {
        /* 
        Actually, we will see current_device == device,  
        which means pytorch always sets the correct device for us.
        But for safety, we still manually set device to the desired one.
        */
        /*
        int current_device;
        checkCudaErrors(cudaGetDevice(&current_device));
        printf("CudaStreamManager construnctor called, get device %d, set device %d\n", current_device, device);
        */
        checkCudaErrors(cudaSetDevice(device));
        
        streams = new cudaStream_t[num_expert];
        checkCudaErrors(cublasCreate(&handle));
        for (size_t i=0; i<num_expert; ++i) {
            checkCudaErrors(cudaStreamCreate(streams+i));
        }
    }
    ~CudaStreamManager() {
        for (size_t i=0; i<num_expert; ++i) {
            checkCudaErrors(cudaStreamDestroy(*(streams+i)));
        }
        checkCudaErrors(cublasDestroy(handle));
    }
    const size_t num_expert;
    const int device;
    cublasHandle_t handle;
    cudaStream_t* streams;
}; 

CudaStreamManager* getCudaStreamManager(const size_t num_expert, const int device);

#endif  // CUDA_STREAM_MANAGER