Refactor Paxos status call to remove type assertion

ipam/allocator.go

@@ -767,7 +767,7 @@ func (alloc *Allocator) update(sender mesh.PeerName, msg []byte) error {
 	//   (if we did so on periodic gossip we would force consensus unnecessarily)
 	// * If we are an elector (to avoid a broadcast storm of ring request messages)
 	default:
-		if _, ok := alloc.paxos.(*paxos.Node); ok && sender != mesh.UnknownPeerName {
+		if alloc.paxos.IsElector() && sender != mesh.UnknownPeerName {
 			alloc.establishRing()
 		}
 	}

ipam/paxos/participant.go

@@ -7,6 +7,7 @@ type Participant interface {
 	Propose()
 	Think() bool
 	Consensus() (bool, AcceptedValue)
+	IsElector() bool
 }
 
 type Observer struct {
@@ -37,3 +38,7 @@ func (observer *Observer) Think() bool {
 func (observer *Observer) Consensus() (bool, AcceptedValue) {
 	return false, AcceptedValue{}
 }
+
+func (observer *Observer) IsElector() bool {
+	return false
+}

ipam/paxos/paxos.go

@@ -257,14 +257,15 @@ func (node *Node) Consensus() (bool, AcceptedValue) {
 	return false, AcceptedValue{}
 }
 
+func (node *Node) IsElector() bool {
+	return true
+}
+
 type Status struct {
 	KnownNodes int
 	Quorum     uint
 }
 
 func NewStatus(node *Node) *Status {
-	if node == nil {
-		return nil
-	}
 	return &Status{len(node.knows), node.quorum}
 }

ipam/status.go

@@ -37,8 +37,10 @@ func NewStatus(allocator *Allocator, defaultSubnet address.CIDR) *Status {
 
 	var paxosStatus *paxos.Status
 	if allocator.awaitingConsensus && allocator.paxos != nil {
-		if node, ok := allocator.paxos.(*paxos.Node); ok {
-			paxosStatus = paxos.NewStatus(node)
+		if allocator.paxos.IsElector() {
+			if node, ok := allocator.paxos.(*paxos.Node); ok {
+				paxosStatus = paxos.NewStatus(node)
+			}
 		}
 	}