#!/usr/bin/env python3
# -*- coding:utf-8 -*-
# Copyright (c) Megvii Inc. All rights reserved.

import os
import subprocess
from loguru import logger

import cv2

from .dist import get_world_size, is_main_process

__all__ = ["configure_nccl", "configure_module", "configure_omp"]


def configure_nccl():
    """Configure multi-machine environment variables of NCCL."""
    os.environ["NCCL_LAUNCH_MODE"] = "PARALLEL"
    os.environ["NCCL_IB_HCA"] = subprocess.getoutput(
        "pushd /sys/class/infiniband/ > /dev/null; for i in mlx5_*; "
        "do cat $i/ports/1/gid_attrs/types/* 2>/dev/null "
        "| grep v >/dev/null && echo $i ; done; popd > /dev/null"
    )
    os.environ["NCCL_IB_GID_INDEX"] = "3"
    os.environ["NCCL_IB_TC"] = "106"


def configure_omp(num_threads=1):
    """
    If OMP_NUM_THREADS is not configured and world_size is greater than 1,
    Configure OMP_NUM_THREADS environment variables of NCCL to `num_thread`.

    Args:
        num_threads (int): value of `OMP_NUM_THREADS` to set.
    """
    # We set OMP_NUM_THREADS=1 by default, which achieves the best speed on our machines
    # feel free to change it for better performance.
    if "OMP_NUM_THREADS" not in os.environ and get_world_size() > 1:
        os.environ["OMP_NUM_THREADS"] = str(num_threads)
        if is_main_process():
            logger.info(
                "\n***************************************************************\n"
                "We set `OMP_NUM_THREADS` for each process to {} to speed up.\n"
                "please further tune the variable for optimal performance.\n"
                "***************************************************************".format(
                    os.environ["OMP_NUM_THREADS"]
                )
            )


def configure_module(ulimit_value=8192):
    """
    Configure pytorch module environment. setting of ulimit and cv2 will be set.

    Args:
        ulimit_value(int): default open file number on linux. Default value: 8192.
    """
    # system setting
    try:
        import resource

        rlimit = resource.getrlimit(resource.RLIMIT_NOFILE)
        resource.setrlimit(resource.RLIMIT_NOFILE, (ulimit_value, rlimit[1]))
    except Exception:
        # Exception might be raised in Windows OS or rlimit reaches max limit number.
        # However, set rlimit value might not be necessary.
        pass

    # cv2
    # multiprocess might be harmful on performance of torch dataloader
    os.environ["OPENCV_OPENCL_RUNTIME"] = "disabled"
    try:
        cv2.setNumThreads(0)
        cv2.ocl.setUseOpenCL(False)
    except Exception:
        # cv2 version mismatch might rasie exceptions.
        pass