From f3f04e64426adcf4f70e91850bf58de3667f78da Mon Sep 17 00:00:00 2001
From: Derek Collison <derek@nats.io>
Date: Thu, 15 Apr 2021 06:24:19 -0700
Subject: [PATCH] Fix flapper

Signed-off-by: Derek Collison <derek@nats.io>
---
 server/jetstream_cluster_test.go | 109 +++++++++++++++----------------
 server/stream.go                 |   3 +
 2 files changed, 54 insertions(+), 58 deletions(-)

diff --git a/server/jetstream_cluster_test.go b/server/jetstream_cluster_test.go
index ed176fdc..a0862af2 100644
--- a/server/jetstream_cluster_test.go
+++ b/server/jetstream_cluster_test.go
@@ -5667,22 +5667,14 @@ func TestJetStreamClusterStreamInfoDeletedDetails(t *testing.T) {
 }
 
 func TestJetStreamClusterMirrorExpirationAndMissingSequences(t *testing.T) {
-	c := createJetStreamClusterExplicit(t, "MMS", 5)
+	c := createJetStreamClusterExplicit(t, "MMS", 9)
 	defer c.shutdown()
 
 	// Client for API requests.
 	nc, js := jsClientConnect(t, c.randomServer())
 	defer nc.Close()
 
-	// Origin
-	_, err := js.AddStream(&nats.StreamConfig{
-		Name:   "TEST",
-		MaxAge: 100 * time.Millisecond,
-	})
-
-	ts := c.streamLeader("$G", "TEST")
-
-	sendBatch := func(t *testing.T, n int) {
+	sendBatch := func(n int) {
 		t.Helper()
 		// Send a batch to a given subject.
 		for i := 0; i < n; i++ {
@@ -5692,9 +5684,9 @@ func TestJetStreamClusterMirrorExpirationAndMissingSequences(t *testing.T) {
 		}
 	}
 
-	checkStream := func(t *testing.T, stream string, num uint64) {
+	checkStream := func(stream string, num uint64) {
 		t.Helper()
-		checkFor(t, 5*time.Second, 50*time.Millisecond, func() error {
+		checkFor(t, 10*time.Second, 50*time.Millisecond, func() error {
 			si, err := js.StreamInfo(stream)
 			if err != nil {
 				return err
@@ -5706,54 +5698,55 @@ func TestJetStreamClusterMirrorExpirationAndMissingSequences(t *testing.T) {
 		})
 	}
 
-	checkMirror := func(t *testing.T, num uint64) { t.Helper(); checkStream(t, "M", num) }
-	checkTest := func(t *testing.T, num uint64) { t.Helper(); checkStream(t, "TEST", num) }
+	checkMirror := func(num uint64) { t.Helper(); checkStream("M", num) }
+	checkTest := func(num uint64) { t.Helper(); checkStream("TEST", num) }
 
-	for _, test := range []struct {
-		name     string
-		replicas int
-	}{
-		{"R-1", 1},
-		{"R-2", 2},
-	} {
-		t.Run(test.name, func(t *testing.T) {
-			// Create mirror now.
-			for ms := ts; ms == ts; {
-				_, err = js.AddStream(&nats.StreamConfig{
-					Name:     "M",
-					Mirror:   &nats.StreamSource{Name: "TEST"},
-					Replicas: test.replicas,
-				})
-				if err != nil {
-					t.Fatalf("Unexpected error: %v", err)
-				}
-				ms = c.streamLeader("$G", "M")
-				if ms == ts {
-					// Delete and retry.
-					js.DeleteStream("M")
-				} else {
-					defer js.DeleteStream("M")
-				}
-			}
-
-			sendBatch(t, 10)
-			checkMirror(t, 10)
-
-			// Now shutdown the server with the mirror.
-			ms := c.streamLeader("$G", "M")
-			ms.Shutdown()
-
-			// Send more messages but let them expire.
-			sendBatch(t, 10)
-			checkTest(t, 0)
-
-			c.restartServer(ms)
-			c.waitOnStreamLeader("$G", "M")
-
-			sendBatch(t, 10)
-			checkMirror(t, 20)
-		})
+	// Origin
+	_, err := js.AddStream(&nats.StreamConfig{
+		Name:   "TEST",
+		MaxAge: 100 * time.Millisecond,
+	})
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
 	}
+
+	ts := c.streamLeader("$G", "TEST")
+	ml := c.leader()
+
+	// Create mirror now.
+	for ms := ts; ms == ts || ms == ml; {
+		_, err = js.AddStream(&nats.StreamConfig{
+			Name:     "M",
+			Mirror:   &nats.StreamSource{Name: "TEST"},
+			Replicas: 2,
+		})
+		if err != nil {
+			t.Fatalf("Unexpected error: %v", err)
+		}
+		ms = c.streamLeader("$G", "M")
+		if ts == ms || ms == ml {
+			// Delete and retry.
+			js.DeleteStream("M")
+		}
+	}
+
+	sendBatch(10)
+	checkMirror(10)
+
+	// Now shutdown the server with the mirror.
+	ms := c.streamLeader("$G", "M")
+	ms.Shutdown()
+
+	// Send more messages but let them expire.
+	sendBatch(10)
+	checkTest(0)
+
+	c.restartServer(ms)
+	c.checkClusterFormed()
+	c.waitOnStreamLeader("$G", "M")
+
+	sendBatch(10)
+	checkMirror(20)
 }
 
 func TestJetStreamClusterMirrorAndSourceExpiration(t *testing.T) {
diff --git a/server/stream.go b/server/stream.go
index 5465a80f..36ce823e 100644
--- a/server/stream.go
+++ b/server/stream.go
@@ -1366,6 +1366,7 @@ func (mset *stream) setupMirrorConsumer() error {
 
 	// Now send off request to create/update our consumer. This will be all API based even in single server mode.
 	// We calculate durable names apriori so we do not need to save them off.
+
 	var state StreamState
 	mset.store.FastState(&state)
 
@@ -1440,7 +1441,9 @@ func (mset *stream) setupMirrorConsumer() error {
 
 				// When an upstream stream expires messages or in general has messages that we want
 				// that are no longer available we need to adjust here.
+				var state StreamState
 				mset.store.FastState(&state)
+
 				if state.LastSeq != ccr.ConsumerInfo.Delivered.Stream {
 					for seq := state.LastSeq + 1; seq <= ccr.ConsumerInfo.Delivered.Stream; seq++ {
 						if mset.node != nil {