37.5-Event总结

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总结：

1. event.wait方法使这个线程只能干这事了；等着任务完成；
2. 一定要知道你当前的代码是在 哪个线程中执行的；

from threading import Event, Thread
import logging
import time

FORMAT = '%(asctime)s %(threadName)s %(thread)d %(message)s'
logging.basicConfig(format=FORMAT, level=logging.INFO)


def boss(event: Event):
    logging.info("I'm boss, waiting for U.")
    # 等待
    event.wait()   # 阻塞，等到返回True；
    logging.info("Good Job.")

def worker(event: Event, count=10):
    logging.info("I'm working for U.")
    cups = []
    while True:
        logging.info('make 1')

        time.sleep(0.5)
        cups.append(1)
        if len(cups) >= count:
            # 通知
            event.set()   # 变为 True;
            break
        logging.info('I finished my job. cups={}'.format(cups))

event = Event()
w = Thread(target=worker, args=(event,))
b = Thread(target=boss, args=(event,))
w.start()
b.start()
#---------------------------------------------------

1. Event练习

实现Timer，延时执行的线程，延时计算add(x,y)；

思路
Timer的构造函数中参数得有哪些？
如何实现start启动一个线程执行函数
如何cancel取消待执行任务

思路实现

from threading import Event, Thread
import logging

logging.basicConfig(level=logging.INFO)

def add(x: int, y: int):
    logging.info(x + y)

class Timer:
    def __init__(self, interval, fn, *args, **kwargs):
        pass

    def start(self):
        pass

    def cancel(self):
        pass

完整实现

from threading import Event, Thread
import datetime
import logging

logging.basicConfig(level=logging.INFO)


def add(x: int, y: int):
    logging.info(x+y)


class Timer:
    def __init__(self,interval,fn,*args,**kwargs):
        self.interval = interval
        self.fn = fn
        self.args = args
        self.kwargs = kwargs
        self.event = Event()

    def start(self):
        Thread(target=self.__run).start()

    def cancel(self):
        self.event.set()

    def __run(self):
        start = datetime.datetime.now()
        logging.info('waiting')

        self.event.wait(self.interval)
        if not self.event.is_set():
            self.fn(*self.args, **self.kwargs)
        delta = (datetime.datetime.now() - start).total_seconds()
        logging.info('finished {}'.format(delta))
        self.event.set()
t = Timer(10, add, 4, 50)

t.start()
e = Event()
e.wait(4)
# t.cancel()
print('==========')
#--------------------------------------------------------------------------------------------
INFO:root:waiting
==========
INFO:root:54
INFO:root:finished 10.000271