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1 # Copyright 2014 The Chromium Authors. All rights reserved. | |
2 # Use of this source code is governed by a BSD-style license that can be | |
3 # found in the LICENSE file. | |
4 | |
5 from future import All, Future | |
6 | |
7 | |
8 class _RefreshWorkOrder(object): | |
9 '''A set of tasks that must be completed in a refresh cycle.''' | |
10 def __init__(self, tasks): | |
11 self.tasks = set(tasks) | |
12 | |
13 | |
14 class _RefreshTaskCompletion(object): | |
15 '''Marks the completion of a single named task for some refresh cycle.''' | |
16 def __init__(self, task): | |
17 self.task = task | |
18 | |
19 | |
20 def _TaskKey(refresh_id, task): | |
21 return '%s@%s' % (refresh_id, task) | |
22 | |
23 | |
24 class RefreshTracker(object): | |
25 '''Manages and tracks the progress of data refresh cycles.''' | |
26 def __init__(self, object_store_creator): | |
27 # These object stores should never be created empty since they are strictly | |
28 # used to persist state across requests. | |
29 self._work_orders = object_store_creator.Create(_RefreshWorkOrder, | |
30 start_empty=False) | |
31 self._task_completions = object_store_creator.Create(_RefreshTaskCompletion, | |
32 start_empty=False) | |
33 | |
34 def _GetWorkOrder(self, refresh_id): | |
35 '''Retrieves the work order for a refresh cycle identified by |id|.''' | |
36 return self._work_orders.Get(refresh_id) | |
37 | |
38 def StartRefresh(self, refresh_id, tasks): | |
39 work_order = _RefreshWorkOrder(tasks) | |
40 return self._work_orders.Set(refresh_id, work_order) | |
41 | |
42 def GetRefreshComplete(self, refresh_id): | |
43 '''Determines if a refresh cycle identified by |id| is complete. Returns | |
44 a |Future| which resolves to either |True| or |False|.''' | |
45 def is_work_order_complete(work_order): | |
46 # If the identified refresh cycle is not known, always return False. | |
47 if work_order is None: | |
48 return False | |
49 return (self._task_completions.GetMulti( | |
50 _TaskKey(refresh_id, task) for task in work_order.tasks) | |
51 .Then(lambda tasks: len(tasks) == len(work_order.tasks))) | |
52 return self._GetWorkOrder(refresh_id).Then(is_work_order_complete) | |
53 | |
54 def MarkTaskComplete(self, refresh_id, task): | |
55 return self._task_completions.Set(_TaskKey(refresh_id, task), | |
56 _RefreshTaskCompletion(task)) | |
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