video_downloader_service/src/core/master_service.py

import asyncio
import concurrent.futures as pool
from functools import partial

from fastapi import HTTPException

from src.core.rabbitmq import get_messages
from src.core.result import Result, ResultTypeEnum
from src.core.ydl import VideoDownloader
from src.exceptions.download_exceptions import SiteNotImplementedException


class MasterService:
    def __init__(self):
        self.loop = asyncio.get_event_loop()
        self.MAX_EXECUTOR_WORKERS = 8
        self.executor = pool.ProcessPoolExecutor(max_workers=self.MAX_EXECUTOR_WORKERS,
                                                 initializer=executor_initializer)
        self.queue = asyncio.Queue()
        self.rabbit_consumer = get_messages
        self.currently_underway = {}  # contains currently in progress videos

    async def run(self):
        # TODO add cleanup procedure for existing exector procs
        tasks = [self.loop.create_task(self.create_workers()) for i in range(self.MAX_EXECUTOR_WORKERS + 1)]

        await asyncio.gather(self.rabbit_consumer(self.queue), *tasks)

    async def create_workers(self):
        while True:
            video_params = await self.queue.get()
            self.currently_underway[video_params['link']] = video_params
            # TODO save current copy of self.currently_underway to DB\file\etc
            download_task = self.loop.run_in_executor(self.executor, partial(
                MasterService.video_processing_executor, video_params=video_params
            )
                                                      )
            if download_task.done():
                result = download_task.result()
            # process result
            self.queue.task_done()

    @staticmethod
    def video_download(video_params: dict):
        ydl_opts = {
            "format": video_params["format"],
            "merge_output_format": video_params["merge_output_format"],
            'outtmpl': video_params["outtmpl"],
        }
        downloader = VideoDownloader(link=video_params["link"], ydl_opts=ydl_opts)
        try:
            result = downloader.download()
            return result
        except SiteNotImplementedException as ex:
            raise HTTPException(
                status_code=400,
                detail=ex.message
            )

    @staticmethod
    def video_processing_executor(video_params: dict):
        # TODO check if video exists on server etc.  Result(type=ResultType.EXISTS, value=False)
        try:
            MasterService.video_download(video_params=video_params)
            return Result(result_type=ResultTypeEnum.DONE)
        except Exception as ex:
            return Result(result_type=ResultTypeEnum.EXCEPTION, value=ex)
        # TODO upload to server


def executor_initializer():
    import setproctitle
    setproctitle.setproctitle(f'video_downloader_executor_process')
    return True