Simple Cron-like scheduler for Python with seconds precision.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 | #! /usr/bin/env python
# -*- coding: iso-8859-1 -*
#
# Copyright (c) 2011 joonis new media
# Author: Thimo Kraemer <thimo.kraemer@joonis.de>
#
# Based on cron.py of Gimli
# http://www.koders.com/python/fidA55A9DB55093A78DD26B55C606B267B2C5063A79.aspx
# and crontab.py of the gnome-schedule-1.1.0 package
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Library General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02110-1301, USA.
import re
import time
import datetime
import calendar
from threading import Thread, Event
YEAR = 0
MONTH = 1
DAY = 2
HOUR = 3
MINUTE = 4
SECOND = 5
WEEKDAY = 6
class SimpleCrontab(object):
"""Crontab-like scheduler.
Only deals with the first 5 fields of a normal crontab entry.
Having 6 fields the first one is used for seconds precision."""
special = {
'@reboot' : '@reboot',
'@hourly' : '0 * * * *',
'@daily' : '0 0 * * *',
'@midnight': '0 * * * *',
'@weekly' : '0 0 * * 0',
'@monthly' : '0 0 1 * *',
'@yearly' : '0 0 1 1 *',
'@annually': '0 0 1 1 *',
}
field_data = {
SECOND : {'name': 'Second', 'min': 0, 'max': 59},
MINUTE : {'name': 'Minute', 'min': 0, 'max': 59},
HOUR : {'name': 'Hour', 'min': 0, 'max': 23},
DAY : {'name': 'Day', 'min': 1, 'max': 31},
MONTH : {'name': 'Month', 'min': 1, 'max': 12,
'enum': ['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec']},
WEEKDAY: {'name': 'Weekday', 'min': 0, 'max': 7,
'enum': ['Sun','Mon','Tue','Wed','Thu','Fri','Sat','Sun']},
YEAR : {'name': 'Year'},
}
def __init__(self, expr, function, *args, **kwargs):
self.__thread = None
self.__stopped = Event()
self.function = function
self.args = args
self.kwargs = kwargs
self.schedule(expr)
def schedule(self, expr):
"""Sets crontab time fields"""
if isinstance(expr, str):
expr = self.special.get(expr, expr)
expr = expr.split()
if expr[0] == '@reboot':
fields = None
else:
expr = list(expr)
if len(expr) == 5:
expr = ['0'] + expr
elif len(expr) != 6:
raise ValueError('Crontab expression needs 5 or 6 fields')
fields = {
SECOND : expr[0],
MINUTE : expr[1],
HOUR : expr[2],
DAY : expr[3],
MONTH : expr[4],
WEEKDAY : expr[5],
}
for field, value in fields.items():
fields[field] = self.__parse_field(field, value)
self.fields = fields
if self.is_running():
self.stop()
self.start()
def __parse_field(self, field, value):
"""Parses and verifies crontab time fields"""
data = self.field_data[field]
timerange = range(data['min'], data['max']+1)
errmsg = 'Must be between %s and %s' % (data['min'], data['max'])
# Replace alias names only if no leading and following alphanumeric and
# no leading slash is present. Otherwise terms like "JanJan" or
# "1Feb" would give a valid check. Values after a slash are stepwidths
# and shouldn't have an alias.
if data.get('enum'):
for i, v in enumerate(data['enum']):
rexp = re.compile('(?<!\w|/)%s(?!\w)' % v, re.IGNORECASE)
value = rexp.sub(str(i+data['min']), value)
value = value.replace('*', '%s-%s' % (data['min'], data['max']))
rexp_step = re.compile('^(\d+-\d+)/(\d+)$')
rexp_range = re.compile('^(\d+)-(\d+)$')
expr_range = []
for value in value.split(','):
# Get stepwidth
result = rexp_step.match(value)
if result:
value, step = result.groups()
step = int(step)
if step == 0 or step not in timerange:
raise ValueError('Invalid stepwidth for field "%s": %s' % (data['name'], step))
else:
step = 1
# Get range
result = rexp_range.match(value)
if result:
start, end = result.groups()
start, end = int(start), int(end)
if not (start in timerange and end in timerange):
raise ValueError('Invalid range for field "%s": %s' % (data['name'], errmsg))
expr_range.extend(range(start, end+1, step))
# Should be single number
elif not value.isdigit():
raise ValueError('Invalid value for field "%s": %s' % (data['name'], value))
elif int(value) not in timerange:
raise ValueError('Value out of range for field "%s": %s' % (data['name'], errmsg))
else:
expr_range.append(int(value))
# Remove duplicates
expr_range = set(expr_range)
# Normalize weekdays, 0-Sun -> 7-Sun
if field == WEEKDAY and 0 in expr_range:
expr_range.remove(0)
expr_range.add(7)
# Sort
expr_range = list(expr_range)
expr_range.sort()
return expr_range
def __calc_next(self, struct, field, value=None, reset=False):
"""Finds next time of execution given the field arg. If value
is different than current one resets all other time fields."""
#print self.field_data[field]['name']
if value is None:
value = struct[field] + 1
if field == DAY:
# Days need some extra work
times = []
last_day = calendar.monthrange(*struct[:2])[1]
limited_days = len(self.fields[DAY]) != 31
limited_weekdays = len(self.fields[WEEKDAY]) != 7
for day in range(1, last_day+1):
if limited_weekdays:
if limited_days and day in self.fields[DAY]:
times.append(day)
else:
weekday = datetime.date(struct[0], struct[1], day).isoweekday()
if weekday in self.fields[WEEKDAY]:
times.append(day)
elif day in self.fields[DAY]:
times.append(day)
elif field == YEAR:
times = [value]
else:
times = self.fields[field]
# Find next time on list
for v in times:
if v >= value:
struct[field] = v
break
else:
# Carry over to previous "parent" field
self.__calc_next(struct, field-1, reset=True)
return False
if field == SECOND:
return True
# Reset all following fields if necessary
if reset or struct[field] != value:
self.__calc_next(struct, field+1, 0, True)
return False
return True
def next_run(self, starting=None):
"""Calculates when the next execution will be.
Type of return value depends on type of input value."""
if not self.fields:
return
timestamp = False
if not starting:
if starting == 0:
timestamp = True
starting = datetime.datetime.now()
elif not isinstance(starting, datetime.datetime):
timestamp = True
starting = datetime.datetime.fromtimestamp(starting)
struct = [starting.year, -1, -1, -1, -1, -1]
# Next month is calculated first as next day depends on it.
# Also if next month is different than time.month the
# function will set up the rest of the fields
self.__calc_next(struct, MONTH, starting.month) and \
self.__calc_next(struct, DAY, starting.day) and \
self.__calc_next(struct, HOUR, starting.hour) and \
self.__calc_next(struct, MINUTE, starting.minute) and \
self.__calc_next(struct, SECOND, starting.second+1)
next = datetime.datetime(*struct)
if timestamp:
next = time.mktime(next.timetuple())
return next
def __run(self, wait):
next = 0
while True:
now = max(next, time.time())
next = self.next_run(now) or now
self.__stopped.wait(next-now)
if self.__stopped.isSet():
break
thread = Thread(target=self.function, args=self.args, kwargs=self.kwargs)
thread.start()
if wait:
thread.join()
if next == now:
break
self.__stopped.set()
def is_running(self):
return self.__thread and self.__thread.isAlive()
def start(self, wait=False):
self.__stopped.clear()
if not self.is_running():
if not hasattr(self.function, '__call__'):
raise ValueError('Callback function not callable')
self.__thread = Thread(target=self.__run, args=(wait,))
self.__thread.start()
def stop(self):
if self.is_running():
self.__stopped.set()
def main():
flag = Event()
flag.set()
def emit(arg):
flag.wait()
flag.clear()
print datetime.datetime.now(), arg
flag.set()
tasks = [
('@reboot', 'reboot'),
('* * * * * *', 'every second'),
(' * * * * *', 'every minute'),
(' */2 * * * *', 'every two minutes'),
('* */3 * * * *', 'every second every three minutes'),
]
crontabs = []
for expr, text in tasks:
cron = SimpleCrontab(expr, emit, text)
cron.start()
crontabs.append(cron)
try:
raw_input('\nPress "Enter" to quit\n\n')
finally:
for cron in crontabs:
cron.stop()
if __name__ == "__main__":
main()
|
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