02_协程真正用途

import asyncio
import time

#
# async def func1():
#     print("我是func1")
#     await asyncio.sleep(1)
#     print("fun1结束")
#
#
# async def func2():
#     print("我是func2")
#     await asyncio.sleep(2)
#     print("fun2结束")
#
#
# async def func3():
#     print("我是func3")
#     await asyncio.sleep(3)
#     print("fun3结束")
#
#
# if __name__ == '__main__':
#     start = time.time()
#     f1 = func1()
#     f2 = func2()
#     f3 = func3()
#     # 把三个任务放一起
#     tasks = [
#         f1,
#         f2,
#         f3,
#     ]
#     asyncio.run(asyncio.wait(tasks))   # wait 等待， 三个任务一起扔过来的，等三个任务全完成才可以
#     # print(time.time() - start)
#

# 协程在爬虫中的真正用法
async def download(url, t):
    print("我要下载了")
    await asyncio.sleep(t)
    print("我下载完了")

async def main():
    # 假设已经有了一堆下载链接
    urls = [
        "http:www.daidu.com",
        "http:www.luoyonghao.com",
        "http:www.qiaofuhaoshuai.com",
    ]
    # 需要封装任务列表
    tasks = []
    for url in urls:
        # 把协程对象变成任务对象
        # 创建任务
        task = asyncio.create_task(download(url, 3))
        # 把任务扔到列表，为了统一处理
        tasks.append(task)
        # tasks.append(download(url, 3))   协程对象
    # 统一等到协程任务执行完毕
    await asyncio.wait(tasks)


if __name__ == '__main__':
    asyncio.run(main())
    # event_loop = asyncio.get_event_loop()
    # event_loop.run_until_complete(main())
"""
未来爬虫：
    1.扫 url，拿到一堆 url
    2.循环 url ，创建任务，
    3.统一 await 
"""