await/async

await

await后必须接一个可等待对象（awaitable object），可等待对象有3类：协程coroutine、任务Task、未来对象Future。

async

async用来修饰函数，被async修饰的函数返回一个协程对象。直接调用async函数不会执行函数，可以用await或asyncio.run等方式来真正执行async函数。

import asyncio

async def foo():
    print('This is a async function!')

async def main():
    await foo()

if __name__ == '__main__':
    # asyncio.run
    obj = foo()
    asyncio.run(obj)

    # await
    asyncio.run(main())

>>> This is a async function!
>>> This is a async function!

asyncio

event loop

事件循环，所有的可等待对象都运行在时间循环里，一个可等待对象只能运行在一个事件循环里，一个事件循环可包含多个可等待对象。

asyncio.get_event_loop()

获取当前事件循环，不存在则创建一个并返回。

asyncio.new_event_loop()

新建事件循环并返回

asyncio.get_running_loop()

返回正在运行的事件循环

example

一个http服务监听两个端口

import asyncio
from aiohttp import web


async def hello(request):
    print(request)
    return web.Response(text='hello')


async def goodbye(request):
    print(request)
    return web.Response(text='goodbye')


async def foo1():
    app = web.Application()
    routes = [web.get('/hello', hello)]
    app.add_routes(routes)
    runner = web.AppRunner(app)
    await runner.setup()
    site = web.TCPSite(runner, host='192.168.30.5', port=12138)
    await site.start()


async def foo2():
    app = web.Application()
    routes = [web.get('/goodbye', goodbye)]
    app.add_routes(routes)
    runner = web.AppRunner(app)
    await runner.setup()
    site = web.TCPSite(runner, host='192.168.30.5', port=12139)
    await site.start()


if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    loop.create_task(foo1())
    loop.create_task(foo2())
    loop.run_forever()

curl 'http://192.168.30.5:12139/goodbye'
goodbye
curl 'http://192.168.30.5:12138/hello' 
hello

python异步http服务 - asyncio

目录