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176 lines
6.7 KiB
Python
176 lines
6.7 KiB
Python
# Copyright (c) 2006-2009 Mitch Garnaat http://garnaat.org/
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#
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# Permission is hereby granted, free of charge, to any person obtaining a
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# copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish, dis-
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# tribute, sublicense, and/or sell copies of the Software, and to permit
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# persons to whom the Software is furnished to do so, subject to the fol-
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# lowing conditions:
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#
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# The above copyright notice and this permission notice shall be included
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# in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABIL-
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# ITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
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# SHALL THE AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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# IN THE SOFTWARE.
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#
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import boto
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from boto.sdb.db.property import StringProperty, DateTimeProperty, IntegerProperty
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from boto.sdb.db.model import Model
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import datetime, subprocess, StringIO, time
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def check_hour(val):
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if val == '*':
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return
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if int(val) < 0 or int(val) > 23:
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raise ValueError
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class Task(Model):
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"""
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A scheduled, repeating task that can be executed by any participating servers.
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The scheduling is similar to cron jobs. Each task has an hour attribute.
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The allowable values for hour are [0-23|*].
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To keep the operation reasonably efficient and not cause excessive polling,
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the minimum granularity of a Task is hourly. Some examples:
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hour='*' - the task would be executed each hour
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hour='3' - the task would be executed at 3AM GMT each day.
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"""
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name = StringProperty()
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hour = StringProperty(required=True, validator=check_hour, default='*')
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command = StringProperty(required=True)
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last_executed = DateTimeProperty()
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last_status = IntegerProperty()
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last_output = StringProperty()
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message_id = StringProperty()
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@classmethod
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def start_all(cls, queue_name):
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for task in cls.all():
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task.start(queue_name)
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def __init__(self, id=None, **kw):
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Model.__init__(self, id, **kw)
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self.hourly = self.hour == '*'
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self.daily = self.hour != '*'
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self.now = datetime.datetime.utcnow()
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def check(self):
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"""
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Determine how long until the next scheduled time for a Task.
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Returns the number of seconds until the next scheduled time or zero
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if the task needs to be run immediately.
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If it's an hourly task and it's never been run, run it now.
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If it's a daily task and it's never been run and the hour is right, run it now.
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"""
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boto.log.info('checking Task[%s]-now=%s, last=%s' % (self.name, self.now, self.last_executed))
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if self.hourly and not self.last_executed:
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return 0
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if self.daily and not self.last_executed:
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if int(self.hour) == self.now.hour:
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return 0
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else:
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return max( (int(self.hour)-self.now.hour), (self.now.hour-int(self.hour)) )*60*60
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delta = self.now - self.last_executed
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if self.hourly:
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if delta.seconds >= 60*60:
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return 0
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else:
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return 60*60 - delta.seconds
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else:
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if int(self.hour) == self.now.hour:
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if delta.days >= 1:
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return 0
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else:
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return 82800 # 23 hours, just to be safe
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else:
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return max( (int(self.hour)-self.now.hour), (self.now.hour-int(self.hour)) )*60*60
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def _run(self, msg, vtimeout):
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boto.log.info('Task[%s] - running:%s' % (self.name, self.command))
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log_fp = StringIO.StringIO()
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process = subprocess.Popen(self.command, shell=True, stdin=subprocess.PIPE,
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stdout=subprocess.PIPE, stderr=subprocess.PIPE)
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nsecs = 5
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current_timeout = vtimeout
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while process.poll() == None:
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boto.log.info('nsecs=%s, timeout=%s' % (nsecs, current_timeout))
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if nsecs >= current_timeout:
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current_timeout += vtimeout
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boto.log.info('Task[%s] - setting timeout to %d seconds' % (self.name, current_timeout))
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if msg:
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msg.change_visibility(current_timeout)
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time.sleep(5)
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nsecs += 5
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t = process.communicate()
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log_fp.write(t[0])
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log_fp.write(t[1])
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boto.log.info('Task[%s] - output: %s' % (self.name, log_fp.getvalue()))
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self.last_executed = self.now
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self.last_status = process.returncode
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self.last_output = log_fp.getvalue()[0:1023]
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def run(self, msg, vtimeout=60):
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delay = self.check()
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boto.log.info('Task[%s] - delay=%s seconds' % (self.name, delay))
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if delay == 0:
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self._run(msg, vtimeout)
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queue = msg.queue
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new_msg = queue.new_message(self.id)
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new_msg = queue.write(new_msg)
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self.message_id = new_msg.id
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self.put()
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boto.log.info('Task[%s] - new message id=%s' % (self.name, new_msg.id))
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msg.delete()
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boto.log.info('Task[%s] - deleted message %s' % (self.name, msg.id))
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else:
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boto.log.info('new_vtimeout: %d' % delay)
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msg.change_visibility(delay)
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def start(self, queue_name):
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boto.log.info('Task[%s] - starting with queue: %s' % (self.name, queue_name))
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queue = boto.lookup('sqs', queue_name)
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msg = queue.new_message(self.id)
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msg = queue.write(msg)
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self.message_id = msg.id
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self.put()
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boto.log.info('Task[%s] - start successful' % self.name)
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class TaskPoller(object):
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def __init__(self, queue_name):
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self.sqs = boto.connect_sqs()
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self.queue = self.sqs.lookup(queue_name)
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def poll(self, wait=60, vtimeout=60):
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while True:
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m = self.queue.read(vtimeout)
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if m:
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task = Task.get_by_id(m.get_body())
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if task:
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if not task.message_id or m.id == task.message_id:
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boto.log.info('Task[%s] - read message %s' % (task.name, m.id))
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task.run(m, vtimeout)
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else:
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boto.log.info('Task[%s] - found extraneous message, ignoring' % task.name)
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else:
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time.sleep(wait)
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