2 files changed, 53 insertions, 5 deletions
diff --git a/internal/quorum/quorum.go b/internal/quorum/quorum.go
index d7fb866..79fea11 100644
--- a/internal/quorum/quorum.go
+++ b/internal/quorum/quorum.go
@@ -11,9 +11,10 @@ import (
 )
 
 type Quorum struct {
-	conf   config.Config
-	votes  map[string]vote.Vote
-	voteCh chan vote.Vote
+	conf          config.Config
+	votes         map[string]vote.Vote
+	voteCh        chan vote.Vote
+	prevLiveNodes []string
 }
 
 type Score struct {
@@ -38,11 +39,15 @@ func (quo Quorum) Start(ctx context.Context) <-chan []string {
 		for {
 			select {
 			case <-time.After(vote.Expiry):
-				liveNodesCh <- quo.deleteExpiredVotes()
+				if liveNodes, changed := quo.liveNodes(); changed {
+					liveNodesCh <- liveNodes
+				}
 			case vote := <-quo.voteCh:
 				quo.vote(vote)
+				if liveNodes, changed := quo.liveNodes(); changed {
+					liveNodesCh <- liveNodes
+				}
 				quo.score()
-				liveNodesCh <- quo.deleteExpiredVotes()
 			case <-ctx.Done():
 				return
 			}
@@ -94,6 +99,26 @@ func (quo Quorum) score() (scores []Score) {
 	return
 }
 
+func (quo *Quorum) liveNodes() ([]string, bool) {
+	newLiveNodes := quo.deleteExpiredVotes()
+	defer func() { quo.prevLiveNodes = newLiveNodes }()
+
+	if len(newLiveNodes) != len(quo.prevLiveNodes) {
+		return newLiveNodes, true
+	}
+
+	for _, x := range newLiveNodes {
+		for _, y := range quo.prevLiveNodes {
+			if x == y {
+				continue
+			}
+			return newLiveNodes, false
+		}
+	}
+
+	return newLiveNodes, true
+}
+
 func (quo Quorum) deleteExpiredVotes() (liveNodes []string) {
 	var expired []string
 
diff --git a/internal/quorum/quorum_test.go b/internal/quorum/quorum_test.go
index ac5cbc6..176a4fb 100644
--- a/internal/quorum/quorum_test.go
+++ b/internal/quorum/quorum_test.go
@@ -125,3 +125,26 @@ func TestExpire(t *testing.T) {
 		t.Errorf("Expected 'foo' to be the live node, but got : %v", liveNodes[0])
 	}
 }
+
+func TestLiveNodes(t *testing.T) {
+	conf := config.Config{Nodes: []string{"foo:1234", "bay:4321"}}
+	quo := New(conf)
+
+	vote1 := vote.New(conf, " foo bar baz bay\n")
+	vote1.ExpiresAt = time.Now().Add(1 * time.Hour)
+	quo.vote(vote1)
+
+	vote2 := vote.New(conf, " bay foo bar baz\n")
+	vote2.ExpiresAt = time.Now().Add(1 * time.Hour)
+	quo.vote(vote2)
+
+	liveNodes, changed := quo.liveNodes()
+	if !changed {
+		t.Errorf("Expected live node list to be changed: %v", liveNodes)
+	}
+
+	liveNodes, changed = quo.liveNodes()
+	if changed {
+		t.Errorf("Expected live node list not to be changed: %v", liveNodes)
+	}
+}