Don't Expect Sorted Nodes From Communication Interface (#182)

* sort nodes in initialize

* comment

Author: samliok

api.go

@@ -54,7 +54,7 @@ type Storage interface {
 
 type Communication interface {
 
-	// Nodes returns all nodes known to the application.
+	// Nodes returns all nodes that participate in the epoch.
 	Nodes() []NodeID
 
 	// Send sends a message to the given destination node

epoch.go

@@ -174,6 +174,8 @@ func (e *Epoch) init() error {
 	e.cancelWaitForBlockNotarization = func() {}
 	e.finishCtx, e.finishFn = context.WithCancel(context.Background())
 	e.nodes = e.Comm.Nodes()
+	sortNodes(e.nodes)
+
 	e.quorumSize = Quorum(len(e.nodes))
 	e.rounds = make(map[uint64]*Round)
 	e.maxRoundWindow = DefaultMaxRoundWindow
@@ -2685,6 +2687,13 @@ func (e *Epoch) isWithinMaxRoundWindow(round uint64) bool {
 	return e.round < round && round-e.round < e.maxRoundWindow
 }
 
+// sortNodes sorts the nodes in place by their byte representations.
+func sortNodes(nodes []NodeID) {
+	slices.SortFunc(nodes, func(a, b NodeID) int {
+		return bytes.Compare(a[:], b[:])
+	})
+}
+
 func LeaderForRound(nodes []NodeID, r uint64) NodeID {
 	n := len(nodes)
 	return nodes[r%uint64(n)]