zones: introduce Zone.ForEachMachine()

and refactor Zones.ForEachMachine() using it

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/zones/zones.go

@@ -22,6 +22,16 @@ func (z *Zone) String() string {
 	return z.Name
 }
 
+// ForEachMachine calls a function for each Machine in the zone
+// until instructed to terminate the loop
+func (z *Zone) ForEachMachine(fn func(*Machine) bool) {
+	for _, p := range z.Machines {
+		if fn(p) {
+			return
+		}
+	}
+}
+
 // Zones represents all zones in a cluster
 type Zones struct {
 	dir      fs.FS
@@ -32,18 +42,22 @@ type Zones struct {
 }
 
 // ForEachMachine calls a function for each Machine in the cluster
+// until instructed to terminate the loop
 func (m *Zones) ForEachMachine(fn func(*Machine) bool) {
-	for _, z := range m.Zones {
-		for _, p := range z.Machines {
-			if fn(p) {
-				// terminate
-				return
-			}
-		}
-	}
+	m.ForEachZone(func(z *Zone) bool {
+		var term bool
+
+		z.ForEachMachine(func(p *Machine) bool {
+			term = fn(p)
+			return term
+		})
+
+		return term
+	})
 }
 
 // ForEachZone calls a function for each Zone in the cluster
+// until instructed to terminate the loop
 func (m *Zones) ForEachZone(fn func(*Zone) bool) {
 	for _, p := range m.Zones {
 		if fn(p) {