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