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342
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1 """
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2 This module defines tasks and a runner for these tasks. Tasks can
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3 have dependencies and it can be determined if they need to be run.
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4 """
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334
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5
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6 import logging
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329
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7
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8 class TaskError(Exception):
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346
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9 def __init__(self, msg):
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10 self.msg = msg
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329
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11
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12
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13 class Task:
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14 """ Task that can run, and depend on other tasks """
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15 def __init__(self, name):
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16 self.name = name
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17 self.completed = False
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342
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18 self.dependencies = set()
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334
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19 self.duration = 1
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329
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20
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21 def run(self):
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22 raise NotImplementedError("Implement this abstract method!")
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23
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24 def fire(self):
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342
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25 """ Wrapper around run that marks the task as done """
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329
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26 assert all(t.completed for t in self.dependencies)
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27 self.run()
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28 self.completed = True
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29
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342
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30 def add_dependency(self, task):
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31 """ Add another task as a dependency for this task """
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32 if task is self:
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33 raise TaskError('Can not add dependency on task itself!')
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34 if self in task.down_stream_tasks:
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35 raise TaskError('Can not introduce circular task')
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36 self.dependencies.add(task)
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37 return task
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329
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38
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342
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39 @property
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40 def down_stream_tasks(self):
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41 """ Return a set of all tasks that follow this task """
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42 # TODO: is this upstream or downstream???
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43 cdst = list(dep.down_stream_tasks for dep in self.dependencies)
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44 cdst.append(self.dependencies)
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45 return set.union(*cdst)
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46
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47 def __gt__(self, other):
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48 return other in self.down_stream_tasks
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329
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49
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332
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50 def __repr__(self):
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51 return 'Task "{}"'.format(self.name)
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52
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329
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53
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342
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54 class EmptyTask(Task):
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55 """ Basic task that does nothing """
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56 def run(self):
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57 pass
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58
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59
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329
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60 class TaskRunner:
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332
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61 """ Basic task runner that can run some tasks in sequence """
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329
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62 def __init__(self):
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334
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63 self.logger = logging.getLogger('taskrunner')
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329
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64 self.task_list = []
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332
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65
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329
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66 def add_task(self, task):
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67 self.task_list.append(task)
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68
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334
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69 @property
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70 def total_duration(self):
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71 return sum(t.duration for t in self.task_list)
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72
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329
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73 def run_tasks(self):
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342
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74 # First sort tasks:
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75 self.task_list.sort()
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76
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77 # Run tasks:
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334
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78 passed_time = 0.0
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79 total_time = self.total_duration
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329
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80 try:
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81 for t in self.task_list:
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334
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82 self.report_progress(passed_time / total_time, t.name)
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329
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83 t.fire()
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334
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84 passed_time += t.duration
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329
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85 except TaskError as e:
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342
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86 self.logger.error(str(e.msg))
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329
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87 return 1
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334
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88 self.report_progress(1, 'OK')
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329
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89 return 0
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332
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90
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91 def display(self):
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92 """ Display task how they would be run """
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93 for task in self.task_list:
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94 print(task)
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334
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95
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96 def report_progress(self, percentage, text):
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97 self.logger.info('[{:3.1%}] {}'.format(percentage, text))
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