ros_topology.py

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# [db] dan@danbrooks.net
#
# diarc topology data structures for ROS
# This renames some things into ROS terminology to be more conveient, and also
# adds some attributes we want to track. 
#
# Renaming Looks like this
#   Vertex = Node
#   Edge = Topic
#   Sink = Subscriber
#   Source = Publisher
#
from diarc.topology import *

class RosSystemGraph(Topology):
    def __init__(self):
        super(RosSystemGraph,self).__init__()

    @property
    def nodes(self):
        return dict([(v.name,v) for v in self.vertices])

    @property
    def topics(self):
        return dict(filter(lambda x: None not in x, [(topic.name,topic) for topic in self.edges]))

    def nextFreeNodeIndex(self):
        """ returns the next available node index """
        return max(self.blocks.keys())+1 if len(self.blocks)>0 else 0
    
    def nextFreeAltitudes(self):
        """ returns a 2-tuple of (posAltitude,negAltitude) of the avaliable altitudes """
        altitudes = [band.altitude for band in self.bands.values()] + [0]
        return (max(altitudes)+1,min(altitudes)-1)




class Node(Vertex):
    def __init__(self,rsg,name=None):
        typecheck(rsg,RosSystemGraph,"rsg")
        super(Node,self).__init__(rsg)

        # dumb placement - just get the next free index
        self.block.index = rsg.nextFreeNodeIndex()

        self.name = name
        self.location = None
        self.pid = None

    @property
    def publishers(self):
        # NOTE: This must be a property function (instead of just saying 
        # self.publishers = self.sources in the constructor) because self.sources
        # just returns a static list once, and we need this to be dynamically
        # queried every time we ask. This is because Vertex.sources and Edge.sources
        # are just syntax sugar for functions that are being called.
        return self.sources

    @property
    def subscribers(self):
        return self.sinks


class Topic(Edge):
    def __init__(self,rsg,name=None,msgType=None):
        typecheck(rsg,RosSystemGraph,"rsg")
        super(Topic,self).__init__(rsg)
        
        # Dumb placement - just get the enxt free altitudes
        self.posBand.altitude,self.negBand.altitude = rsg.nextFreeAltitudes()
        self.posBand.rank = self.posBand.altitude
        self.negBand.rank = self.posBand.altitude

        self.name = name
        self.msgType = msgType

    @property
    def publishers(self):
        # NOTE: See note on Node class about why this MUST be a property.
        return self.sources

    @property
    def subscribers(self):
        # NOTE: See note on Node class about why this MUST be a property.
        return self.sinks




class Publisher(Source):
    def __init__(self,rsg,node,topic):
        typecheck(rsg,RosSystemGraph,"rsg")
        typecheck(node,Node,"node")
        typecheck(topic,Topic,"topic")
        super(Publisher,self).__init__(rsg,node,topic)
        # Dumb placement
        self.snap.order = max(filter(lambda x: isinstance(x,int), [pub.snap.order for pub in node.publishers] + [-1]))+1

        self.bandwidth = None
        self.msgType = None

    @property
    def topic(self):
        # NOTE: See note on Node class about why this MUST be a property.
        return self.edge

    @property
    def node(self):
        # NOTE: See note on Node class about why this MUST be a property.
        return self.vertex

class Subscriber(Sink):
    def __init__(self,rsg,node,topic):
        typecheck(rsg,RosSystemGraph,"rsg")
        typecheck(node,Node,"node")
        typecheck(topic,Topic,"topic")
        super(Subscriber,self).__init__(rsg,node,topic)

        # Dumb placement
        self.snap.order = max(filter(lambda x: isinstance(x,int), [sub.snap.order for sub in node.subscribers] + [-1]))+1

        self.bandwidth = None
        self.msgType = None

    @property
    def topic(self):
        # NOTE: See note on Node class about why this MUST be a property.
        return self.edge

    @property
    def node(self):
        # NOTE: See note on Node class about why this MUST be a property.
        return self.vertex