// outputDotFile generates a .dot file describing the current state of
// the gossip network. nodes is a map from network address to gossip
// node. edgeSet is empty on the first invocation, but
// its content is set to encompass the entire set of edges in the
// network when this method returns. It should be resupplied with each
// successive invocation, as it is used to determine which edges are
// new and which have been deleted and show those changes visually in
// the output graph. New edges are drawn green; edges which were
// removed over the course of the last simulation step(s) are drawn in
// a lightly-dashed red.
//
// The format of the output looks like this:
//
//   digraph G {
//   node [shape=record];
//        node1 [fontsize=12,label="{Node 1|MH=3}"]
//        node1 -> node3 [color=green]
//        node1 -> node4
//        node1 -> node5 [color=red,style=dotted]
//        node2 [fontsize=24,label="{Node 2|MH=2}"]
//        node2 -> node5
//        node3 [fontsize=18,label="{Node 3|MH=5}"]
//        node3 -> node5
//        node3 -> node4
//        node4 [fontsize=24,label="{Node 4|MH=4}"]
//        node4 -> node2
//        node5 [fontsize=24,label="{Node 5|MH=1}"]
//        node5 -> node2
//        node5 -> node3
//   }
func outputDotFile(dotFN string, cycle int, network *simulation.Network, edgeSet map[string]edge) string {
	f, err := os.Create(dotFN)
	if err != nil {
		log.Fatalf("unable to create temp file: %s", err)
	}
	defer f.Close()

	// Determine maximum number of incoming connections. Create outgoing
	// edges, keeping track of which are new since last time (added=true).
	outgoingMap := make(edgeMap)
	var maxIncoming int
	// The order the graph file is written influences the arrangement
	// of nodes in the output image, so it makes sense to eliminate
	// randomness here. Unfortunately with graphviz it's fairly hard
	// to get a consistent ordering.
	for _, simNode := range network.Nodes {
		node := simNode.Gossip
		incoming := node.Incoming()
		for _, iNode := range incoming {
			e := edge{dest: node.GetNodeID()}
			key := fmt.Sprintf("%d:%d", iNode, node.GetNodeID())
			if _, ok := edgeSet[key]; !ok {
				e.added = true
			}
			delete(edgeSet, key)
			outgoingMap.addEdge(iNode, e)
		}
		if len(incoming) > maxIncoming {
			maxIncoming = len(incoming)
		}
	}

	// Find all edges which were deleted.
	for key, e := range edgeSet {
		e.added = false
		e.deleted = true
		nodeID, err := strconv.Atoi(strings.Split(key, ":")[0])
		if err != nil {
			log.Fatal(err)
		}
		outgoingMap.addEdge(roachpb.NodeID(nodeID), e)
		delete(edgeSet, key)
	}

	f.WriteString("digraph G {\n")
	f.WriteString("node [shape=record];\n")
	for _, simNode := range network.Nodes {
		node := simNode.Gossip
		var incomplete int
		var totalAge int64
		for _, addr := range network.Addrs {
			infoKey := addr.String()
			if infoKey == simNode.Addr.String() {
				continue // skip the node's own info
			}
			if val, err := node.GetInfo(infoKey); err != nil {
				log.Infof("error getting info for key %q: %s", infoKey, err)
				incomplete++
			} else {
				totalAge += int64(cycle) - val.(int64)
			}
		}

		var sentinelAge int64
		if val, err := node.GetInfo(gossip.KeySentinel); err != nil {
			log.Infof("error getting info for sentinel gossip key %q: %s", gossip.KeySentinel, err)
		} else {
			sentinelAge = int64(cycle) - val.(int64)
		}

//.........这里部分代码省略.........

// outputDotFile generates a .dot file describing the current state of
// the gossip network. nodes is a map from network address to gossip
// node. edgeSet is empty on the first invocation, but
// its content is set to encompass the entire set of edges in the
// network when this method returns. It should be resupplied with each
// successive invocation, as it is used to determine which edges are
// new and which have been deleted and show those changes visually in
// the output graph. New edges are drawn green; edges which were
// removed over the course of the last simulation step(s) are drawn in
// a lightly-dashed red.
//
// The format of the output looks like this:
//
//   digraph G {
//   node [shape=record];
//        node1 [fontsize=12,label="{Node 1|MH=3}"]
//        node1 -> node3 [color=green]
//        node1 -> node4
//        node1 -> node5 [color=red,style=dotted]
//        node2 [fontsize=24,label="{Node 2|MH=2}"]
//        node2 -> node5
//        node3 [fontsize=18,label="{Node 3|MH=5}"]
//        node3 -> node5
//        node3 -> node4
//        node4 [fontsize=24,label="{Node 4|MH=4}"]
//        node4 -> node2
//        node5 [fontsize=24,label="{Node 5|MH=1}"]
//        node5 -> node2
//        node5 -> node3
//   }
//
// Returns the name of the output file and a boolean for whether or not
// the network has quiesced (that is, no new edges, and all nodes are
// connected).
func outputDotFile(dotFN string, cycle int, network *simulation.Network, edgeSet map[string]edge) (string, bool) {
	f, err := os.Create(dotFN)
	if err != nil {
		log.Fatalf(context.TODO(), "unable to create temp file: %s", err)
	}
	defer f.Close()

	// Determine maximum number of incoming connections. Create outgoing
	// edges, keeping track of which are new since last time (added=true).
	outgoingMap := make(edgeMap)
	var maxIncoming int
	quiescent := true
	// The order the graph file is written influences the arrangement
	// of nodes in the output image, so it makes sense to eliminate
	// randomness here. Unfortunately with graphviz it's fairly hard
	// to get a consistent ordering.
	for _, simNode := range network.Nodes {
		node := simNode.Gossip
		incoming := node.Incoming()
		for _, iNode := range incoming {
			e := edge{dest: node.GetNodeID()}
			key := fmt.Sprintf("%d:%d", iNode, node.GetNodeID())
			if _, ok := edgeSet[key]; !ok {
				e.added = true
				quiescent = false
			}
			delete(edgeSet, key)
			outgoingMap.addEdge(iNode, e)
		}
		if len(incoming) > maxIncoming {
			maxIncoming = len(incoming)
		}
	}

	// Find all edges which were deleted.
	for key, e := range edgeSet {
		e.added = false
		e.deleted = true
		quiescent = false
		nodeID, err := strconv.Atoi(strings.Split(key, ":")[0])
		if err != nil {
			log.Fatal(context.TODO(), err)
		}
		outgoingMap.addEdge(roachpb.NodeID(nodeID), e)
		delete(edgeSet, key)
	}

	fmt.Fprintln(f, "digraph G {")
	fmt.Fprintln(f, "node [shape=record];")
	for _, simNode := range network.Nodes {
		node := simNode.Gossip
		var missing []roachpb.NodeID
		var totalAge int64
		for _, otherNode := range network.Nodes {
			if otherNode == simNode {
				continue // skip the node's own info
			}
			infoKey := otherNode.Addr().String()
			// GetInfo returns an error if the info is missing.
			if info, err := node.GetInfo(infoKey); err != nil {
				missing = append(missing, otherNode.Gossip.GetNodeID())
				quiescent = false
			} else {
				_, val, err := encoding.DecodeUint64Ascending(info)
				if err != nil {
					log.Fatalf(context.TODO(), "bad decode of node info cycle: %s", err)
//.........这里部分代码省略.........