delay a task until certain time

What I want to do in a python script is sleep a number of seconds until the required time is reached. IE: if runAt setting is 15:20 and current time is 10:20, how can I work out how many seconds to sleep? I'm not sure how to convert 15:20 to a time and current date then deduct the actual time t开发者_JAVA百科o get the seconds.

---

Think you can also use the following code:

from datetime import datetime, time
from time import sleep

def act(x):
    return x+10

def wait_start(runTime, action):
    startTime = time(*(map(int, runTime.split(':'))))
    while startTime > datetime.today().time(): # you can add here any additional variable to break loop if necessary
        sleep(1)# you can change 1 sec interval to any other
    return action

wait_start('15:20', lambda: act(100))

---

If you subtract one datetime object from another you get a timedelta object, which has a seconds property, so you can do:

t1 = datetime.datetime.now()

# other stuff here
t2 = datetime.datetime.now()
delta = t2 - t1
if delta.seconds > WAIT:
    # do stuff
else:
    # sleep for a bit

As an aside, you might want to use cron for tasks that are supposed to run at specific times.

---

You could instead use the pause package ( https://pypi.python.org/pypi/pause ). Taking an example from their documentation -

import pause, datetime
dt = datetime.datetime(2013, 6, 2, 14, 36, 34, 383752)
pause.until(dt)

---

Using timedelta object is the way to go. Below is the example that worked for me and can easily be adjusted to any other time:

import datetime, time
today = datetime.datetime.now()

sleep = (datetime.datetime(today.year, today.month, today.day, 15, 20, 0) - today).seconds
print('Waiting for ' + str(datetime.timedelta(seconds=sleep)))
time.sleep(sleep)

Take into consideration that if 15:20 has already passed, this substraction will still work and will wait till the next occurrence of 15:20, because in such situations timedelta returns a negative number of days. It's 16:15 as I'm running my code:

print(datetime.datetime(today.year, today.month, today.day, 15, 20, 0) - today)
>>>-1 day, 23:05:00.176033

---

Instead of using the function sleep(X), you can also use to a Timer

It depends on what you're planning to do.

---

Here's a solution that uses the Arrow module:

def wait_until(specified_dt: arrow.Arrow) -> None:
"""Stay in a loop until the specified date and time."""
# Initially check every 10 seconds.
refresh = 10
current_dt = arrow.utcnow()

while current_dt < specified_dt:
    # Check every millisecond if close to the specified time.
    current_dt = arrow.utcnow()
    if (specified_dt - current_dt).seconds < 11:
        refresh = .001

    time.sleep(refresh)

---

Here is a solution. This is independent of date because the new date-time "end2" has same date as current date-time and at the same time the date-time format is not changed.

from datetime import datetime               #this is the way to import a module named datetime...
import time                                 #this module is used to sleep
import pause

a = (datetime.now())                        #a = '2017-07-27 00:10:00.107000' #for example
print 'the time is'
print a

end2 = a.replace(hour = 15, minute = 20, second = 00)

delta = end2 - a
print delta                                 # prints:  5:00:00
print delta.total_seconds()                 # prints: 114605.0
pause.seconds(delta.total_seconds())

---

Using both arrow and pause:

maintenance = arrow.now()
EndAt = maintenance.replace(hour = 17, minute = 6, second = 0)
print(maintenance,': Maintenance in progress. Pausing until :',EndAt)
pause.until(EndAt.naive)