c 异步编程_.net 异步编程_task异步编程

只有进入 PENDING 状态下的任务才可以取消c 异步编程，FINISHED状态不可以取消。。。。。。。

使用 KeyboardInterrupt 来接收终止事件

import asyncio
async def work(id, t):
    print('Working...')
    await asyncio.sleep(t)
    print('Work {} done'.format(id))
if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    coroutines = [work(i, i) for i in range(1, 4)]
    try:
        loop.run_until_complete(asyncio.gather(*coroutines))
    except KeyboardInterrupt:  # 接收终端事件，结束事件循环中全部的pending任务
        loop.stop()
    finally:
        loop.close()

在任务执行过程中 ctrl+c，直接更改还未完成的任务

Working...
Working...
Working...
Work 1 done
Work 2 done
^C

通过 asyncio.Task.all_tasks 获取全部任务并获取它们的状况

import asyncio
async def work(id, t):
    print('Working...')
    await asyncio.sleep(t)
    print('Work {} done'.format(id))
if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    coroutines = [work(i, i) for i in range(1, 4)]
    try:
        loop.run_until_complete(asyncio.gather(*coroutines))
    except KeyboardInterrupt:
        tasks = asyncio.Task.all_tasks()
        for i in tasks:
            print('取消任务：{}'.format(i._state))
            print('取消状态：{}'.format(i.cancel()))
    finally:
        loop.close()

效果如下c 异步编程，在执行过程中输入 ctrl+c

Working...
Working...
Working...
Work 1 done
^C取消任务：PENDING
取消状态：True
取消任务：FINISHED
取消状态：False
取消任务：PENDING
取消状态：True

asyncio的eventloop提供了一系列函数来处理异步函数执行的难题

下面是一个整合的反例

import asyncio
import functools
def normal_func(name: str):
    print('[normal_func] triggered by {}'.format(name))
def loop_stop(loop: asyncio.AbstractEventLoop, future: asyncio.Future):
    loop.stop()
async def work(t: int, name: str):
    print('[{}] start'.format(name))
    await asyncio.sleep(t)
    print('[{}] after {}s stop'.format(name, t))
if __name__ == '__main__':
    # asyncio.ensure_future
    # loop.create_Task
    # loop.run_until_complete
    loop = asyncio.get_event_loop()
    start = loop.time()
    tasks = asyncio.gather(work(1, '1'), work(4, '2'))
    loop.call_soon(normal_func, 'call_soon')
    loop.call_later(2, normal_func, 'call_later')
    loop.call_at(start + 3, normal_func, 'call_at')
    tasks.add_done_callback(functools.partial(loop_stop, loop))
    loop.run_forever()  # 无限运行事件循环，直至 loop.stop 停止
    loop.close()  # 关闭事件循环，只有 loop 处于停止状态才会执行

结果如下

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