python 事件驱动 asyncio

1 Asyncio loop = get_event_loop(): 得到当前上下文的事件循环。 loop.call_later(time_delay, callback, argument): 延后 time_delay 秒再执行 callback 方法。 loop.call_soon(callback, argument): 尽可能快调用 callback, call_soon() 函数结束，主线程回到事件循环之后就会马上调用 callback 。 loop.time(): 以float类型返回当前时间循环的内部时间。 asyncio.set_event_loop(): 为当前上下文设置事件循环。 asyncio.new_event_loop(): 根据此策略创建一个新的时间循环并返回。 loop.run_forever(): 在调用 stop() 之前将一直运行。

2、执行：总执行9秒 import asyncio import datetime import time

def function_1(end_time, loop): print ("function_1 called {}".format(loop.time())) if (loop.time() + 1.0) < end_time: loop.call_later(1, function_2, end_time, loop) else: loop.stop()

def function_2(end_time, loop): print ("function_2 called ".format(loop.time())) if (loop.time() + 1.0) < end_time: loop.call_later(1, function_3, end_time, loop) else: loop.stop()

def function_3(end_time, loop): print ("function_3 called".format(loop.time())) if (loop.time() + 1.0) < end_time: loop.call_later(1, function_1, end_time, loop) else: loop.stop()

def function_4(end_time, loop): print ("function_5 called") if (loop.time() + 1.0) < end_time: loop.call_later(1, function_4, end_time, loop) else: loop.stop()

loop = asyncio.get_event_loop()

end_loop = loop.time() + 9.0 print(end_loop) loop.call_soon(function_1, end_loop, loop)

loop.call_soon(function_4, end_loop, loop)

loop.run_forever() loop.close()

3、@asyncio.coroutine yield from 协程

Asyncio Finite State Machine

import asyncio import time from random import randint

@asyncio.coroutine def StartState(): print("Start State called \n") input_value = randint(0, 1) time.sleep(1) if (input_value == 0): result = yield from State2(input_value) else: result = yield from State1(input_value) print("Resume of the Transition : \nStart State calling " + result)

@asyncio.coroutine def State1(transition_value): outputValue = str("State 1 with transition value = %s \n" % transition_value) input_value = randint(0, 1) time.sleep(1) print("...Evaluating...") if input_value == 0: result = yield from State3(input_value) else : result = yield from State2(input_value) result = "State 1 calling " + result return outputValue + str(result)

@asyncio.coroutine def State2(transition_value): outputValue = str("State 2 with transition value = %s \n" % transition_value) input_value = randint(0, 1) time.sleep(1) print("...Evaluating...") if (input_value == 0): result = yield from State1(input_value) else : result = yield from State3(input_value) result = "State 2 calling " + result return outputValue + str(result)

@asyncio.coroutine def State3(transition_value): outputValue = str("State 3 with transition value = %s \n" % transition_value) input_value = randint(0, 1) time.sleep(1) print("...Evaluating...") if (input_value == 0): result = yield from State1(input_value) else : result = yield from EndState(input_value) result = "State 3 calling " + result return outputValue + str(result)

@asyncio.coroutine def EndState(transition_value): outputValue = str("End State with transition value = %s \n" % transition_value) print("...Stop Computation...") return outputValue

if name == "main": print("Finite State Machine simulation with Asyncio Coroutine") loop = asyncio.get_event_loop() loop.run_until_complete(StartState())

5、asyncio.Task 并行执行这三个任务，我们将其放到一个task的list中： """ Asyncio using Asyncio.Task to execute three math function in parallel """ import asyncio @asyncio.coroutine def factorial(number): f = 1 for i in range(2, number + 1): print("Asyncio.Task: Compute factorial(%s)" % (i)) yield from asyncio.sleep(1) f *= i print("Asyncio.Task - factorial(%s) = %s" % (number, f))

@asyncio.coroutine def fibonacci(number): a, b = 0, 1 for i in range(number): print("Asyncio.Task: Compute fibonacci (%s)" % (i)) yield from asyncio.sleep(1) a, b = b, a + b print("Asyncio.Task - fibonacci(%s) = %s" % (number, a))

@asyncio.coroutine def binomialCoeff(n, k): result = 1 for i in range(1, k+1): result = result * (n-i+1) / i print("Asyncio.Task: Compute binomialCoeff (%s)" % (i)) yield from asyncio.sleep(1) print("Asyncio.Task - binomialCoeff(%s , %s) = %s" % (n, k, result))

if name == "main": tasks = [asyncio.Task(factorial(10)), asyncio.Task(fibonacci(10)), asyncio.Task(binomialCoeff(20, 10))] loop = asyncio.get_event_loop() loop.run_until_complete(asyncio.wait(tasks)) loop.close()

python3 task.py Asyncio.Task: Compute factorial(2) Asyncio.Task: Compute fibonacci (0) Asyncio.Task: Compute binomialCoeff (1) Asyncio.Task: Compute factorial(3) Asyncio.Task: Compute fibonacci (1) Asyncio.Task: Compute binomialCoeff (2) Asyncio.Task: Compute factorial(4) Asyncio.Task: Compute fibonacci (2) Asyncio.Task: Compute binomialCoeff (3) Asyncio.Task: Compute factorial(5) Asyncio.Task: Compute fibonacci (3) Asyncio.Task: Compute binomialCoeff (4) Asyncio.Task: Compute factorial(6) Asyncio.Task: Compute fibonacci (4) Asyncio.Task: Compute binomialCoeff (5) Asyncio.Task: Compute factorial(7) Asyncio.Task: Compute fibonacci (5) Asyncio.Task: Compute binomialCoeff (6) Asyncio.Task: Compute factorial(8) Asyncio.Task: Compute fibonacci (6) Asyncio.Task: Compute binomialCoeff (7) Asyncio.Task: Compute factorial(9) Asyncio.Task: Compute fibonacci (7) Asyncio.Task: Compute binomialCoeff (8) Asyncio.Task: Compute factorial(10) Asyncio.Task: Compute fibonacci (8) Asyncio.Task: Compute binomialCoeff (9) Asyncio.Task - factorial(10) = 3628800 Asyncio.Task: Compute fibonacci (9) Asyncio.Task: Compute binomialCoeff (10) Asyncio.Task - fibonacci(10) = 55 Asyncio.Task - binomialCoeff(20 , 10) = 184756.0