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Concurrence容器
Description: 本教程教会你如何使用Concurrence容器Tutorial Level: BEGINNER
Next Tutorial: Sequence容器
Contents
1 from smach import Concurrence
指定concurrence输出
Concurrence输出图
SMACH并发的输出图指定了基于其子结果确定并发结果的策略。具体来说，map是一个字典，其中键是并发的潜在结果，而值是将子标签映射到子结果的词典。一旦并发的所有状态都终止了，如果满足了这些子结果映射的一个，并发将返回其关联的结果。如果没有映射得到满足，则并发将返回其默认结果。
1 cc = Concurrence(outcomes = ['outcome1', 'outcome2'],
2 default_outcome = 'outcome1',
3 input_keys = ['sm_input'],
4 output_keys = ['sm_output'],
5 outcome_map = {'succeeded':{'FOO':'succeeded',
6 'BAR':'outcome2'},
7 'outcome3':{'FOO':'outcome2'}})
8 with cc:
9 Concurrence.add('FOO', Foo())
10 Concurrence.add('BAR', Bar())
上面的示例指定了以下策略:
- 当'FOO'有结果'成功'，'BAR'有结果'outcome2'时，状态机将退出，结果'成功'。
- 当'FOO'有结果'outcome2', 状态机将以'outcome3'为结果退出, 独立于状态BAR的结果。
回调
如果你想要完整控制一整个concurrence状态机，你可以使用它提供的回调：child_termination_cb和outcome_cb:
1 # gets called when ANY child state terminates
2 def child_term_cb(outcome_map):
3
4 # terminate all running states if FOO finished with outcome 'outcome3'
5 if outcome_map['FOO'] == 'outcome3':
6 return True
7
8 # terminate all running states if BAR finished
9 if outcome_map['BAR']:
10 return True
11
12 # in all other case, just keep running, don't terminate anything
13 return False
14
15
16 # gets called when ALL child states are terminated
17 def out_cb(outcome_map):
18 if outcome_map['FOO'] == 'succeeded':
19 return 'outcome1'
20 else:
21 return 'outcome2'
22
23
24 # creating the concurrence state machine
25 sm = Concurrence(outcomes=['outcome1', 'outcome2'],
26 default_outcome='outcome1',
27 input_keys=['sm_input'],
28 output_keys=['sm_output'],
29 child_termination_cb = child_term_cb,
30 outcome_cb = out_cb)
31
32 with sm:
33 Concurrence.add('FOO', Foo(),
34 remapping={'foo_in':'input'})
35
36 Concurrence.add('BAR', Bar(),
37 remapping={'bar_out':'bar_out'})
- 当一个子状态终止时，将调用child_termination_cb。在回调函数中，你可以决定状态机是否应该继续运行(返回False)，或者是否应该抢占所有剩余的运行状态(返回True)。
- 当最后一个子状态终止时，outcome_cb被调用一次。这个回调返回并发状态机的结果。
