python裝飾器實現週期性函數調用

python的裝飾器可用於權限校驗，週期性函數調用等功能，下面通過兩種方式實現週期性函數的調用。

# -*- coding:utf-8 -*-
from functools import wraps
import time
import datetime

_ts = lambda: time.time()

# 通過__call__實現裝飾器類
class PeriodLoopingCall:
    def __init__(self, period=60, max_count=0):
        self.period = period
        self.count = max_count

    def __call__(self, func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            while self.count > 0:
                start_time = _ts()
                func(*args, **kwargs)
                self.count -= 1
                end_time = _ts()
                delay = end_time - start_time - self.period
                time.sleep(-delay if delay < 0 else 0)
        return wrapper

# 通過閉包實現裝飾器函數
# 由於使用了nonlocal，需要在python 3環境下運行
def period_exec_func(period=60, max_count=0):
    def decorator(func):
        #使用functools.wraps函數防止原始函數的屬性被裝飾器函數的屬性替換。
        #即防止這裏的print_info函數屬性被wrapper函數屬性替換。
        count = 0
        @wraps(func)
        def wrapper(*args, **kwargs):
            nonlocal count
            while count < max_count:
                start_time = _ts()
                func(*args, **kwargs)
                count += 1
                end_time = _ts()
                delay = end_time - start_time - period
                time.sleep(-delay if delay < 0 else 0)
        return wrapper
    return decorator

@period_exec_func(period=2, max_count=3)
def print_info1(info):
    date = datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S')
    info = "%s %s" %(date, info)
    print(info)

@PeriodLoopingCall(period=2, max_count=3)
def print_info2(info):
    date = datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S')
    info = "%s %s" %(date, info)
    print(info)

def main():
    info1 = "This is period decorator function test"
    print_info1(info1)

    print("*"*60)

    info2 = "This is period decorator class test"
    print_info2(info2)


if __name__ == "__main__":
    main()

運行結果：

2019-10-20 11:09:48 This is period decorator function test
2019-10-20 11:09:50 This is period decorator function test
2019-10-20 11:09:52 This is period decorator function test
************************************************************
2019-10-20 11:09:54 This is period decorator class test
2019-10-20 11:09:56 This is period decorator class test
2019-10-20 11:09:58 This is period decorator class test