Change the type of entry.Free to address.Count

This change is backward compatible, because the underlying types of
address.Offset (the previous type) and address.Count are the same
and the Gob encoder does not require types to exactly correspond.

ipam/ring/entry.go

@@ -14,8 +14,7 @@ type entry struct {
 	Token   address.Address // The start of this range
 	Peer    mesh.PeerName   // Who owns this range
 	Version uint32          // Version of this range
-	Free    address.Offset  // Number of free IPs in this range
-	// Note: Free should perhaps be an address.Count, but we can't change the wire protocol
+	Free    address.Count   // Number of free IPs in this range
 }
 
 func (e *entry) Equal(e2 *entry) bool {
@@ -23,7 +22,7 @@ func (e *entry) Equal(e2 *entry) bool {
 		e.Version == e2.Version
 }
 
-func (e *entry) update(peername mesh.PeerName, free address.Offset) {
+func (e *entry) update(peername mesh.PeerName, free address.Count) {
 	e.Peer = peername
 	e.Version++
 	e.Free = free

ipam/ring/ring.go

@@ -109,12 +109,12 @@ func (r *Ring) Range() address.Range {
 
 // Returns the distance between two tokens on this ring, dealing
 // with ranges which cross the origin
-func (r *Ring) distance(start, end address.Address) address.Offset {
+func (r *Ring) distance(start, end address.Address) address.Count {
 	if end > start {
-		return address.Offset(end - start)
+		return address.Count(end - start)
 	}
 
-	return address.Offset((r.End - start) + (end - r.Start))
+	return address.Count((r.End - start) + (end - r.Start))
 }
 
 // GrantRangeToHost modifies the ring such that range [start, end)
@@ -375,12 +375,12 @@ func (r *Ring) ClaimForPeers(peers []mesh.PeerName) {
 	defer r.updateExportedVariables()
 
 	totalSize := r.distance(r.Start, r.End)
-	share := totalSize/address.Offset(len(peers)) + 1
-	remainder := totalSize % address.Offset(len(peers))
+	share := totalSize/address.Count(len(peers)) + 1
+	remainder := totalSize % address.Count(len(peers))
 	pos := r.Start
 
 	for i, peer := range peers {
-		if address.Offset(i) == remainder {
+		if address.Count(i) == remainder {
 			share--
 			if share == 0 {
 				break
@@ -450,11 +450,11 @@ func (r *Ring) ReportFree(freespace map[address.Address]address.Count) {
 		maxSize := r.distance(entry.Token, next.Token)
 		common.Assert(free <= address.Count(maxSize))
 
-		if address.Count(entries[i].Free) == free {
+		if entries[i].Free == free {
 			return
 		}
 
-		entries[i].Free = address.Offset(free)
+		entries[i].Free = free
 		entries[i].Version++
 	}
 }
@@ -473,7 +473,7 @@ func (ws weightedPeers) Swap(i, j int)      { ws[i], ws[j] = ws[j], ws[i] }
 // ChoosePeersToAskForSpace returns all peers we can ask for space in
 // the range [start, end), in weighted-random order.  Assumes start<end.
 func (r *Ring) ChoosePeersToAskForSpace(start, end address.Address) []mesh.PeerName {
-	totalSpacePerPeer := make(map[mesh.PeerName]address.Offset)
+	totalSpacePerPeer := make(map[mesh.PeerName]address.Count)
 
 	// iterate through tokens
 	for i, entry := range r.Entries {

net/address/address.go

@@ -151,7 +151,7 @@ func Length(a, b Address) Count {
 	return Count(a - b)
 }
 
-func Min(a, b Offset) Offset {
+func Min(a, b Count) Count {
 	if a > b {
 		return b
 	}