python - python tornado periodCallback在特定时间

Question

我的目标很简单：在特定时间启动周期性回调。我试图到处寻找，但所有阅读的示例都与当前时间的时间增量有关，而不是与定义的时间有关。

我写一个简单的例子。

import tornado.ioloop
import datetime
from datetime import date, time
from tornado.ioloop import IOLoop, PeriodicCallback

def startService():
    print("periodic thing")


def periodicCallback():
    periodic = PeriodicCallback(callback=startService,callback_time=5000)
    periodic.start()

if __name__ == "__main__":
    main_loop = IOLoop.instance()
    # I want to set a specific time
    starting_time = time(14, 30, 00)
    # After this time i would want to have the message "periodic thing" every callback_time
    (...)
    #my first test but i have error about deadline unsupported:
    IOLoop.current().add_timeout(starting_time, periodicCallback)
    main_loop.start()

感谢帮助

Answer 1

Unsupported deadline您看到的错误是因为add_timeout需要一个datetime.timedelta对象，而您正在给它一个datetime.time对象。

由于您想在特定时间运行回调，因此您可以计算到该时间的时间增量。

import datetime

# see the current time
now = datetime.datetime.now()

# create a datetime object for your desired time
starting_time = datetime.datetime(year=2018, month=3, day=13, 
                                  hour=14, minute=30) 

# subtract `now` from `starting_time`
# to calculate timedelta
td = starting_time - now

main_loop.add_timeout(td, periodicCallback)

---

如果year或month或与时间day相同now，您还可以这样做：

starting_time = datetime.datetime(year=now.year, month=now.month, day=now.day, 
                                  hour=14, minute=30)