如何获取通过 asyncio task 方式运行的函数的返回值：

• asyncio.wait
• asyncio.gather
• future.result

asyncio.wait 与 asyncio.gather 对比：

asyncio.wait 比 asynci.gather 更低级，asyncio.gather 主要集中在收集结果，它等待并按给定的顺序返回其结果，asyncio.wait 只是等待，它不是直接给出结果，而是给出已完成和挂起的任务。

asyncio.gather 允许对任务进行高级别分组；asyncio.wait 支持在完成第一个任务后或在指定的超时之后等待停止，从而允许操作的精度降低。

async.gather

#!/usr/bin/env python3
import asyncio

async def func_normal():
    print('A')
    await asyncio.sleep(5)
    print('B')
    return 'saad'

async def func_infinite():
    for i in range(10):
        print("--%d" % i)
    return 'saad2'

loop = asyncio.get_event_loop()
tasks = [func_normal(), func_infinite()]
results = loop.run_until_complete(asyncio.gather(*tasks))
print("func_normal()={}, func_infinite()={}".format(*results))
loop.close()

async.wait

import asyncio

async def func_normal():
    print("A")
    await asyncio.sleep(5)
    print("B")
    return 'saad'

async def func_infinite():
    i = 0
    while i<10:
        print("--"+str(i))
        i = i+1
    return('saad2')

loop = asyncio.get_event_loop()

tasks = [ func_normal(), func_infinite()]

done, _ = loop.run_until_complete(asyncio.wait(tasks))
for fut in done:
    print("return value is {}".format(fut.result()))
loop.close()

也可以通过

print(tasks[0].result())
print(tasks[1].result())    

获取对应的结果

future.result

import asyncio


async def func_normal(future):
    print("A")
    await asyncio.sleep(5)
    print("B")
    # return 'saad'
    future.set_result('saad')


async def func_infinite(future):
    i = 0
    while i<10:
        print("--"+str(i))
        i = i+1
    # return('saad2')
    future.set_result('saad2')

def got_result(future):
    print(future.result())

loop = asyncio.get_event_loop()
future1 = asyncio.Future()
future2 = asyncio.Future()

future1.add_done_callback(got_result)
future2.add_done_callback(got_result)

# Coros are automatically wrapped in Tasks by asyncio.wait() 
coros = [
    func_normal(future1),
    func_infinite(future2)]

loop.run_until_complete(asyncio.wait(coros))
loop.close()