refactor to per-node snmp polling and immediate arp dump

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

arp.go

@@ -15,8 +15,6 @@ func (t *Tendrils) pollARP(ctx context.Context) {
 	ticker := time.NewTicker(30 * time.Second)
 	defer ticker.Stop()
 
-	t.readARPTable()
-
 	for {
 		select {
 		case <-ctx.Done():
@@ -35,7 +33,6 @@ type arpEntry struct {
 
 func (t *Tendrils) readARPTable() {
 	entries := t.parseARPTable()
-
 	localNode := t.getLocalNode()
 
 	for _, entry := range entries {
@@ -65,7 +62,7 @@ func (t *Tendrils) parseARPTable() []arpEntry {
 }
 
 func (t *Tendrils) parseARPDarwin() []arpEntry {
-	cmd := exec.Command("arp", "-a")
+	cmd := exec.Command("arp", "-an")
 	output, err := cmd.Output()
 	if err != nil {
 		return nil

nodes.go

@@ -1,11 +1,13 @@
 package tendrils
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"net"
 	"sort"
 	"sync"
+	"time"
 
 	"github.com/fvbommel/sortorder"
 )
@@ -104,6 +106,7 @@ type Node struct {
 	Interfaces  map[string]*Interface
 	MACTable    map[string]string // peer MAC -> local interface name
 	PoEBudget   *PoEBudget
+	pollTrigger chan struct{}
 }
 
 func (n *Node) String() string {
@@ -135,20 +138,31 @@ type Nodes struct {
 	nodes       map[int]*Node
 	ipIndex     map[string]int
 	macIndex    map[string]int
+	nodeCancel  map[int]context.CancelFunc
 	nextID      int
 	t           *Tendrils
+	ctx         context.Context
+	cancelAll   context.CancelFunc
 }
 
 func NewNodes(t *Tendrils) *Nodes {
+	ctx, cancel := context.WithCancel(context.Background())
 	return &Nodes{
 		nodes:      map[int]*Node{},
 		ipIndex:    map[string]int{},
 		macIndex:   map[string]int{},
+		nodeCancel: map[int]context.CancelFunc{},
 		nextID:     1,
 		t:          t,
+		ctx:        ctx,
+		cancelAll:  cancel,
 	}
 }
 
+func (n *Nodes) Shutdown() {
+	n.cancelAll()
+}
+
 func (n *Nodes) Update(target *Node, mac net.HardwareAddr, ips []net.IP, ifaceName, nodeName, source string) {
 	n.mu.Lock()
 	defer n.mu.Unlock()
@@ -184,18 +198,22 @@ func (n *Nodes) Update(target *Node, mac net.HardwareAddr, ips []net.IP, ifaceNa
 		}
 	}
 
+	var node *Node
 	if targetID == -1 {
 		targetID = n.nextID
 		n.nextID++
-		n.nodes[targetID] = &Node{
+		node = &Node{
 			Interfaces:  map[string]*Interface{},
 			MACTable:    map[string]string{},
+			pollTrigger: make(chan struct{}, 1),
 		}
+		n.nodes[targetID] = node
 		isNew = true
+		n.startNodePoller(targetID, node)
+	} else {
+		node = n.nodes[targetID]
 	}
 
-	node := n.nodes[targetID]
-
 	var added []string
 	if mac != nil {
 		added = n.updateNodeInterface(node, targetID, mac, ips, ifaceName)
@@ -206,6 +224,14 @@ func (n *Nodes) Update(target *Node, mac net.HardwareAddr, ips []net.IP, ifaceNa
 		added = append(added, "name="+nodeName)
 	}
 
+	hasNewIP := false
+	for _, a := range added {
+		if len(a) > 3 && a[:3] == "ip=" {
+			hasNewIP = true
+			break
+		}
+	}
+
 	if len(added) > 0 {
 		if n.t.LogEvents {
 			if isNew {
@@ -218,6 +244,38 @@ func (n *Nodes) Update(target *Node, mac net.HardwareAddr, ips []net.IP, ifaceNa
 			n.logNode(node)
 		}
 	}
+
+	if hasNewIP {
+		n.triggerPoll(node)
+	}
+}
+
+func (n *Nodes) startNodePoller(nodeID int, node *Node) {
+	ctx, cancel := context.WithCancel(n.ctx)
+	n.nodeCancel[nodeID] = cancel
+
+	go func() {
+		ticker := time.NewTicker(10 * time.Second)
+		defer ticker.Stop()
+
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-node.pollTrigger:
+				n.t.pollNode(node)
+			case <-ticker.C:
+				n.t.pollNode(node)
+			}
+		}
+	}()
+}
+
+func (n *Nodes) triggerPoll(node *Node) {
+	select {
+	case node.pollTrigger <- struct{}{}:
+	default:
+	}
 }
 
 func (n *Nodes) updateNodeInterface(node *Node, nodeID int, mac net.HardwareAddr, ips []net.IP, ifaceName string) []string {

snmp.go

@@ -1,7 +1,6 @@
 package tendrils
 
 import (
-	"context"
 	"fmt"
 	"log"
 	"net"
@@ -80,35 +79,24 @@ func (t *Tendrils) connectSNMP(ip net.IP) (*gosnmp.GoSNMP, error) {
 	return snmp, nil
 }
 
-func (t *Tendrils) pollSNMP(ctx context.Context) {
+func (t *Tendrils) pollNode(node *Node) {
-	ticker := time.NewTicker(10 * time.Second)
+	if t.DisableSNMP {
-	defer ticker.Stop()
-
-	t.querySwitches()
-
-	for {
-		select {
-		case <-ctx.Done():
 		return
-		case <-ticker.C:
-			t.querySwitches()
-		}
-	}
 	}
 
-func (t *Tendrils) querySwitches() {
+	t.nodes.mu.RLock()
-	nodes := t.nodes.All()
+	var ips []net.IP
-
-	for _, node := range nodes {
 	for _, iface := range node.Interfaces {
 		for _, ip := range iface.IPs {
-				if ip.To4() == nil {
+			if ip.To4() != nil {
-					continue
+				ips = append(ips, ip)
 			}
+		}
+	}
+	t.nodes.mu.RUnlock()
 
-				go t.querySNMPDevice(node, ip)
+	for _, ip := range ips {
-			}
+		t.querySNMPDevice(node, ip)
-		}
 	}
 }
 

tendrils.go

@@ -48,11 +48,9 @@ func (t *Tendrils) Run() {
 	t.populateLocalAddresses()
 
 	if !t.DisableARP {
+		t.readARPTable()
 		go t.pollARP(ctx)
 	}
-	if !t.DisableSNMP {
-		go t.pollSNMP(ctx)
-	}
 
 	ticker := time.NewTicker(1 * time.Second)
 	defer ticker.Stop()