#!/usr/bin/python3
""" Test script for lru_timestamp function.
usage: lru.py [-h] [-r REFRESH] [-s SLEEP]
optional arguments:
-h, --help show this help message and exit
-r REFRESH, --refresh REFRESH
refresh interval (default 60 min)
-s SLEEP, --sleep SLEEP
sleep interval (default 10 min)
"""
import argparse
import datetime
import functools
import random
import time
def lru_timestamp(refresh_interval=60):
""" Return a timestamp string for @lru_cache decorated functions.
The returned timestamp is used as the value of an extra parameter
to @lru_cache decorated functions, allowing for more control over
how often cache entries are refreshed. The lru_timestamp function
should be called with the same refresh_interval value for a given
@lru_cache decorated function. The returned timestamp is for the
benefit of the @lru_cache decorator and is normally not used by
the decorated function.
Positional arguments:
refresh_interval -- in minutes (default 60), values less than 1
are coerced to 1, values more than 1440 are
coerced to 1440
"""
if not isinstance(refresh_interval, int):
raise TypeError('refresh_interval must be an int from 1-1440')
dt = datetime.datetime.now()
if refresh_interval > 60:
refresh_interval = min(refresh_interval, 60*24)
fmt = '%Y%m%d'
minutes = dt.hour * 60
else:
refresh_interval = max(1, refresh_interval)
fmt = '%Y%m%d%H'
minutes = dt.minute
ts = dt.strftime(fmt)
age = minutes // refresh_interval
return '{0}:{1:d}'.format(ts, age)
@functools.lru_cache()
def calulate(x, y, timestamp):
""" Return random int for testing lru_timestamp function."""
print('performing calculation (not from cache), timestamp:', timestamp)
return random.randint(x, y)
def init():
""" Return parsed command line args."""
random.seed()
parser = argparse.ArgumentParser(fromfile_prefix_chars='@')
parser.add_argument('-r', '--refresh', type=int, dest='refresh',
default=60, help='refresh interval (default 60 min)')
parser.add_argument('-s', '--sleep', type=int, dest='sleep', default=10,
help='sleep interval (default 10 min)')
return parser.parse_args()
def main():
""" Script main."""
args = init()
print('refresh interval (min):', args.refresh)
print('sleep interval (min):', args.sleep)
print()
refresh = args.refresh
doze = args.sleep * 60
#num = calulate(1, 1000, lru_timestamp('junk'))
#num = calulate(1, 1000, lru_timestamp(1.22))
#num = calulate(1, 1000, lru_timestamp(-1))
#num = calulate(1, 1000, lru_timestamp(2000))
while True:
num = calulate(1, 1000, lru_timestamp(refresh))
print('calculation returned', num)
time.sleep(doze)
if __name__ == '__main__':
main()
