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1 """each node descends from this base class"""
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2
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3 class Node:
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4 def __init__(self):
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5 """TBD"""
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6 self.ops = Ops()
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7 ''' there should be default ports, just to give people a template:
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8 self.iports = [InputPort("default")]
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9 self.oports = [OutputPort("default")]
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10
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11 # no params
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12 self.params = []
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13
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14 # initialize state with created op? no way
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15 # here's why: 1. we would need to pass stateaccess into this function
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16 # and they would be allowed to initialize their state here
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17 # 2. scheduler/statemanager will call created when it's good and ready,
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18 # ok? no need to push it!
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19 # unless... we should put real init code in NodeType or Node(Instance)
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20 # inits. that might be better than having a whole op for it.
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21
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22 '''
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23 def get_state(self, stateaccess):
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24 """This is similar to the pickle.__getstate__ method, except
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25 we need this alternate version in order to give the node
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26 (which holds no state) access to its instance's state.
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27
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28 If your node keeps some transient items in its state dict
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29 (such as a buffer of recently received inputs), it may want to
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30 return a copy of the state dict without those items. set_state
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31 should restore them properly (if they're missing from the
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32 current state, which they might not be).
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33
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34 get_state might be called at any time, and it's certainly not
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35 guaranteed that the node instance is going out of service.
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36 get_state might get called to checkpoint the nodes for a
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37 backup, for example. set_state might also get called anytime.
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38 """
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39 return stateaccess
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40 def set_state(self, stateaccess, dict):
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41 """dict (named after the pickle.__setstate__ argument) is
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42 always a value that was previously returned from
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43 get_state. Don't adjust the current node's state, of course;
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44 use dict to update stateaccess. If there were elements
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45 missing from dict (see the note in get_state for why this
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46 might be the case), you should restore them here as
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47 appropriate.
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48 """
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49 stateaccess.update(dict)
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50
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51 # warning: pseduocode
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52 class NodeInstance:
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53 ip_addr?
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54 get_this_nodes_url()
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55
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56 type = the node type (a subclass of Node)
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57 ops (get from type)
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58 input,output = the ports that are created for the node instance
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59 state = associated state
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60
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61
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