timewrapper.py

import logging
import StringIO
import traceback
import time

class NapWrapper(object):
    ''' This is the minumum base wrapper interface to comunicate directly with the scheduler. The things you have to do is up to you in each method. You may consider to create a wrapper for long running tasks, if you like to have progress control.
    '''

    def __init__(self, sleep, pipe=None, logger=logging,**kwargs):
        self.pipe = pipe
        self.logger = logger
        self.sleep = sleep
        # The rest of your init here


    def set_cycle(self, cycle_dt):
        '''(Optional) This function will be called by the scheduler passing a datetime object in UTC representing the current cycle or current run time. That's how the system tells to your process in which cycle to run.
        '''
        self.cycle = cycle_dt


    def set_progress(self, partial, total, message):
        '''(Optional) Just for long runing (+10min) tasks that you may consider to use this function, you may call it whenever you want to comunicate progess.
        Must send trough the pipe 2 numbers and a string in a tuple, 
        '''
        if hasattr(self.pipe, 'send'):
            self.pipe.send((partial, total, message))

    def run(self):
        ''' Executes the process, you can return a result or send the traceback on the pipe. The result can be used as arg for a suposed linked action to be executed after this. If an error occours you may send the traceback back to scheduler using the pipe, so can be visualized in the web interface or in the error email.
        '''
        try:
            self.logger.info('Started sleep task at cycle %s' % self.cycle)
            for i in range(self.sleep):
                time.sleep(1)
                self.set_progress(i, self.sleep, 'sleeping for %d' % self.sleep-i )
            return 'Took nap of %d seconds' % self.sleep
        except Exception as exc:
            tb_buff = StringIO.StringIO()
            traceback.print_exc(file=tb_buff)
            tb = tb_buff.getvalue()
            if hasattr(self.pipe, 'send'):
                self.pipe.send((tb))
            raise exc